Opening-Wedge High Tibial Osteotomy: Review of 100 Consecutive Cases Steven A. Giuseffi, M.D., William H. Replogle, Ph.D., and Walter R. Shelton, M.D.
Purpose: We report intermediate-term outcomes of a large consecutive series of medial opening-wedge tibial osteotomies. Methods: One hundred consecutive patients who underwent medial high tibial osteotomy from 2004-2013 were retrospectively reviewed. Charts were reviewed for patient age and gender, knee pain and range of motion, smoking status, and body mass index. Operative reports were reviewed for bone graft type, degree of correction, and osteotomy fixation method. Radiographs were evaluated for lateral cortical or intra-articular fracture, osteotomy healing, and preoperative and postoperative tibiofemoral angles. Results: Eighty-nine osteotomies (89%) in 83 patients were included in the study. Most procedures were performed for medial knee arthritis. The mean age at surgery was 48.1 years, and the mean follow-up period was 4.0 years. The mean tibiofemoral alignment was 3.2 of varus preoperatively and 6.4 of valgus postoperatively. Plate and screw fixation was used in all cases. Bone grafting methods included autograft, allograft, iliac crest aspirate, platelet-rich plasma, and demineralized bone matrix. Of the osteotomies, 83 (93%) healed uneventfully. Five nonunions and 1 delayed union occurred. Allograft combined with demineralized bone matrix and/or platelet-rich plasma was associated with nonunion (P ¼ .02). Lateral cortical fracture was associated with repeat surgery for nonunion or alignment loss (P ¼ .02). Pain was minimal or mild in 65% of patients, moderate in 16%, and severe in 19%. Osteotomy fixation with a small 4-screw plate was associated with increased postoperative pain (P ¼ .01). Seven patients underwent arthroplasty an average of 5 years after osteotomy. The need for arthroplasty was associated with longer follow-up (P ¼ .02) and use of a smaller plate (P ¼ .04). Conclusions: Uncomplicated osteotomy union occurred in 93% of medial opening-wedge high tibial osteotomies. Allograft mixed with demineralized bone matrix and/or plateletrich plasma was associated with nonunion. At intermediate follow-up, 65% of patients had minimal or mild pain. Seven patients had undergone arthroplasty. Fixation with a smaller plate was associated with increased postoperative pain and the need for subsequent arthroplasty. Level of Evidence: Level IV, therapeutic case series.
H
igh tibial osteotomy (HTO) is a surgical option for the treatment of varus gonarthrosis or varus malalignment with coexisting medial chondral defects, medial meniscal deficiency, or lateral ligamentous insufficiency. HTO is particularly indicated for the treatment of unicompartmental degenerative arthritis
From Mississippi Sports Medicine and Orthopaedic Center (S.A.G., W.R.S.), and the Department of Family Medicine, University of Mississippi Medical Center (W.H.R.), Jackson, Mississippi, U.S.A. Presented at the Spring Arthroscopy Association of North America Annual Meeting, Hollywood, FL, May, 2014. The authors report the following potential conflict of interest or source of funding: W.R.S. is chair of the Physicians Surgery Center, and he receives royalties as a consultant for Smith & Nephew. Received July 19, 2014; accepted April 30, 2015. Address correspondence to Walter R. Shelton, M.D., Mississippi Sports Medicine and Orthopaedic Center, 1325 E Fortification St, Jackson, MS 39202, U.S.A. E-mail: [email protected] Ó 2015 by the Arthroscopy Association of North America 0749-8063/14631/$36.00 http://dx.doi.org/10.1016/j.arthro.2015.04.097
in the young, active patient in whom implant arthroplasty may not be ideal.1,2 Studies have shown that offloading an arthritic knee compartment can lead to symptomatic improvement and possibly cartilage regeneration.3-10 HTO can be performed through a lateral closingwedge or medial opening-wedge technique. The literature does not support the superiority of one technique over the other, and the choice is largely one of surgeon preference.11,12 Medial opening-wedge osteotomy allows the surgeon to avoid tibiofibular joint disruption, minimize the risk of peroneal nerve injury, and preserve tibial bone stock.2 Disadvantages include the need for a bone graft, increased risk of nonunion, and the possibility of loss of correction due to osteotomy collapse.1,2 Our study reports the intermediate-term outcomes of a large, single-center consecutive series of medial opening-wedge HTOs. The study goals were to determine the effect of bone graft type and fixation method on osteotomy union and maintenance of alignment, to
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assess clinical outcomes, and to analyze failures. We hypothesized that (1) use of a larger plate would improve union rates and decrease loss of correction, (2) union of the osteotomy would be enhanced by combining iliac crest bone marrow aspirate with allograft cancellous bone graft, and (3) medial openingwedge HTO would provide satisfactory intermediateterm clinical outcomes in most patients.
Methods After institutional review board approval, we retrospectively reviewed the results of all patients who underwent medial opening-wedge HTO by the senior author (W.R.S.) from 2004-2013. No patients were excluded. The primary indication for HTO was painful varus gonarthrosis in a young, active patient. Additional indications were varus malalignment with associated medial osteochondral defects, medial meniscal deficiency, or lateral ligamentous instability. The other parameters were as follows: patient age younger than 60 years, knee flexion contracture of less than 10 and knee flexion greater than 90 , medial-compartment radiographic degenerative changes that did not exceed Kellgren-Lawrence grade 3, and lateral-compartment cartilage status no worse than Outerbridge grade 2. Patient age and gender, knee pain and range of motion, smoking status, and body mass index (BMI) were documented along with bone graft type, osteotomy fixation method, and status of meniscal-chondral and ligamentous structures. Radiographs were evaluated to assess preoperative and postoperative tibiofemoral angles, intraoperative lateral cortical or intra-articular fracture, and osteotomy healing. The minimum follow-up period was set at 1 year. Statistical analysis was performed with c2 tests for associations between nominal predictors and outcomes and with independent t tests for nominal predictors and interval scaled outcomes. A Kaplan-Meier curve was constructed to illustrate arthroplasty-free HTO survival. An a level of .05 was used to determine statistical significance. For primary outcome measures, such as union versus nonunion, the study was powered to detect an event rate of a binary predictor of 20%. Multivariate analysis was performed when relevant, except when low outcome numbers precluded such analysis. Surgical Technique Preoperative template planning is performed according to the method of Dugdale et al.13 After tourniquet inflation, diagnostic arthroscopy is performed to document medial-compartment arthritis and to assess the status of the lateral and patellofemoral compartments and menisci. An anteromedial skin incision is made along the proximal tibia and carried through the sartorial fascia to the pes tendons, which are retracted
posteriorly. A Chandler retractor is placed subperiosteally around the posterior tibial cortex to protect the posterior neurovascular structures. The patellar tendon is identified and retracted anteriorly. A guide pin is inserted along the template-determined osteotomy line, which is made proximal to the tibial tubercle starting medially along the metaphyseal flare and aiming laterally toward the fibular head.14 A saw is used to cut the medial cortex of the tibial shaft to a depth of 2 cm along the guide pin. The knee is placed in 90 of flexion, and the posterior cut is made with a wide calibrated osteotome to within 10 mm of the lateral tibial cortex, thus avoiding lateral cortical disruption.15 The anterior osteotome cut is made with the knee extended and the patellar tendon retracted. Calibrated wedges are used to open the osteotomy to the desired mechanical axis correction. Care is taken to preserve the posterior tibial slope, and the anterior osteotomy gap is routinely two-thirds the posterior gap.16-18 The tourniquet is deflated before bone grafting and plate fixation to confirm the integrity of the popliteal vasculature. Bone graft is impacted into the osteotomy site. For the first 47 osteotomies in the series, various bone grafts were used, including allograft, allograft with demineralized bone matrix (DBM), allograft with platelet-rich plasma (PRP), and iliac crest autograft. Starting with osteotomy 48, all subsequent patients received cancellous allograft combined with 20 mL of autogenous iliac crest aspirate. An appropriatelysized Arthrex wedge plate (Arthrex, Naples, FL) is used to fix the osteotomy. A separate lateral lag screw is placed from proximal-medial to distal-lateral to prevent late unhinging of the lateral osteotomy site. Fluoroscopy is used to confirm correction of the mechanical axis according to the preoperative template. Patients are restricted to toe-touch weight bearing until 6 weeks, at which time progressive weight bearing is initiated if radiographs show evidence of healing. Figure 1 shows a typical postoperative radiograph.
Results Minimum 1-year follow-up was available for 89 osteotomies (89%) in 83 patients. The mean patient age at osteotomy was 48.1 years, and the mean follow-up period was 4.0 years (range, 1.0 to 10.0 years). The mean weight-bearing alignment was 3.2 of varus preoperatively and 6.4 of valgus postoperatively. Uncomplicated osteotomy healing occurred in 83 of 89 osteotomies (93%). Five nonunions and 1 delayed union were noted. Nonunion occurred in 2 of 17 smokers (11.8%) versus 3 of 72 nonsmokers (4.2%) (P ¼ .22). There was a trend toward increased nonunion in female patients (3 of 27 [11.1%] v 2 of 62 male patients [3.2%]), but this did not reach statistical significance (P ¼ .14). Patient
OPENING-WEDGE HIGH TIBIAL OSTEOTOMY
Fig 1. Typical radiograph of a left knee showing plate and screw fixation immediately postoperatively. The prophylactic “lock-down” lag screw across the lateral osteotomy hinge should be noted.
age and BMI were not associated with nonunion (P ¼ .65 and P ¼ .71, respectively). The first 47 osteotomies in this series were fixed with a small 4-screw plate and multiple types of bone graft (allograft plus DBM, n ¼ 21; allograft plus PRP, n ¼ 13; allograft alone, n ¼ 10; and iliac crest autograft, n ¼ 3). Nonunion in this group was problematic (5 of 47). All 5 nonunions occurred in the allograft-plus-DBM (n ¼ 3) and allograft-plus-PRP (n ¼ 2) groups (P ¼ .02) and with the use of a small plate (P ¼ .09). In an attempt to improve the results, the senior author made 2 significant changes in technique. Starting with osteotomy 48, subsequent patients (42) underwent bone grafting with cancellous allograft combined with 20 mL of autogenous iliac crest aspirate. Starting with patient 59, all subsequent osteotomies (31) underwent fixation with a large plate using 3 screws proximally and 3 screws distally. No nonunion occurred with the use of allograft
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plus iliac crest aspirate or with the use of a larger plate. Figures 2 and 3 show the relation between osteotomy union and plate and graft type. Four patients had loss of coronal alignment. Nonunion did not develop in any of these patients. One had an intraoperative lateral cortical fracture fixed with a lag screw outside of the plate but lost correction despite this fixation. The other 3 patients lost alignment despite use of prophylactic lag screws across the lateral osteotomy hinge. Two of these 3 patients lost correction after falls, and another lost alignment on returning to heavy mechanic work 3 months postoperatively. Two of the 4 patients who lost coronal alignment underwent revision osteotomy fixation and uneventfully healed in terms of desired valgus alignment. Another patient sustained a fall after hardware removal and had a fracture through the osteotomy site. She was successfully treated with closed reduction and casting. The remaining patient declined revision osteotomy. Female gender was associated with subsequent loss of coronal alignment (P ¼ .05). The amount of intraoperative coronal axis correction (P ¼ .53) was not associated with subsequent loss of coronal alignment, nor was patient BMI (P ¼ .61) or smoking status (P ¼ .11). Neither bone graft (P ¼ .32) nor plate type (P ¼ .67) was associated with correction loss. Because lateral lag screws were used in all but 3 patients, we were unable to statistically evaluate how these screws affected maintenance of alignment. Five patients had intraoperative lateral cortical fractures, all of which underwent lag screw fixation. One progressed to nonunion. Another lost coronal alignment, as described earlier. The trend toward nonunion in the setting of lateral cortical fracture was not significant (P ¼ .18). Loss of correction occurred in 3 of 84 osteotomies (3.6%) with an intact lateral cortex compared with 1 of 5 (20%) with a lateral cortical fracture. This trend was marginally significant (P ¼ .08). However, lateral cortical fracture was significantly associated with the need for repeat surgery for alignment loss or nonunion (P ¼ .02). Table 1 shows the relation between lateral cortical fracture and osteotomy union, maintenance of alignment, and the need for repeat surgery. Nondisplaced intra-articular fractures occurred in 6 patients. None of these intra-articular fractures or their associated osteotomies progressed to nonunion. Older age was associated with intra-articular fracture (P ¼ .04), whereas gender was not (P ¼ .45). Intraarticular fracture was not associated with increased postoperative pain (P ¼ .56) or the need for repeat surgery (P ¼ .82). No association was seen between intra-articular fracture and plate (P ¼ .51) or graft (P ¼ .42) type or degree of intraoperative correction (P ¼ .49).
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lateral ligamentous instability. Table 2 shows the pathology, treatment, and outcomes of these patients.
Fig 2. Osteotomy union rate categorized by high tibial osteotomy fixation method (P ¼ .09): plate with 2 proximal and 2 distal screws (2þ2 Plate) and plate with 3 proximal and 3 distal screws (3þ3 Plate).
Postoperative visual analog scale pain values were specifically documented for 82 of 89 osteotomies (92%) at the time of final follow-up. Patient age, patient gender, degree of mechanical axis correction, graft type, and final tibiofemoral alignment were not associated with subjective patient pain scores (P ¼ .92, P ¼ .43, P ¼ .99, P ¼ .18, and P ¼ .86, respectively). No association was seen between smoking status (P ¼ .73) or nonunion (P ¼ .16) and postoperative pain. Osteotomy fixation with a smaller plate with 2 proximal and 2 distal screws was associated with increased postoperative pain (P ¼ .001). This association remained significant (P ¼ .03) even after correction for length of follow-up and patient BMI, which was marginally associated with increased postoperative pain (P ¼ .06). Visual analog scale pain outcomes are shown in Figure 4. Seven patients underwent arthroplasty a mean of 5 years (range, 1.0 to 8.7 years) after the index osteotomy. The mean age at osteotomy for patients who went on to undergo arthroplasty was 51.1 years, as compared with 47.7 years for those who did not require arthroplasty. This was not statistically significant (P ¼ .28). Similarly, patient gender, BMI, smoking status, and graft type were not associated with subsequent arthroplasty (P ¼ .92, P ¼ .74, P ¼ .61, and P ¼ .18, respectively). The need for arthroplasty was associated with a longer follow-up time, with a mean follow-up time of 6.0 years in the arthroplasty group versus 3.8 years in patients who did not require arthroplasty (P ¼ .02). Use of a smaller plate was also associated with the need for subsequent arthroplasty (P ¼ .04). Arthroplasty-free osteotomy survival is shown in Figure 5. Eight osteotomies were performed to treat focal medial cartilage defects, medial meniscal deficiency, or
Complications Six patients had mild (mean, 4 ) loss of knee extension. Three patients had knee flexion loss, with 2 of these unable to flex their knees beyond 90 . Four patients required intravenous antibiotics for cellulitis. No patient required operative debridement for infection or hematoma. A nonfatal pulmonary embolism occurred 2 months after osteotomy in 1 patient, and a lower extremity deep venous thrombosis developed in another patient. One patient had a popliteal artery thrombosis at 5 days postoperatively and underwent vascular surgery. Fortunately, this patient recovered and had no residual neurovascular deficits. Overall, 25 patients (28%) underwent further surgery related to the index osteotomy. Excluding elective hardware removal, which comprised most cases, 15 of 88 patients (17%) required subsequent surgery. Five patients underwent surgery for nonunion, and 2 underwent revision fixation for loss of coronal alignment. As described earlier, 1 patient underwent vascular surgery. Arthroplasty was required in 7 patients.
Discussion Nonunion rates varied significantly according to osteotomy graft type. Allograft mixed with DBM and/or
Fig 3. High tibial osteotomy union rate according to graft type. Allograft (Allo) plus platelet-rich plasma (PRP) and allograft plus PRP and demineralized bone matrix (DBM) were associated with nonunion (P ¼ .02). (ICA, iliac crest aspirate; ICBG, iliac crest bone graft.)
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Table 1. Lateral Cortical Fracture Intact lateral cortex Lateral cortical fracture
Nonunion 4 of 84 (4.8%) 1 of 5 (20%)
Coronal Alignment Loss 3 of 84 (3.6%) 1 of 5 (20%)
Nonunion or Alignment Loss 7 of 84 (8.3%) 2 of 5 (40%)
NOTE. An association was found between lateral cortical fracture and osteotomy nonunion (P ¼ .18) and between lateral cortical fracture and coronal alignment loss (P ¼ .08). In addition, lateral cortical fracture was associated with revision surgery for nonunion or alignment loss (P ¼ .02).
PRP was associated with an increased nonunion rate (P ¼ .02). Allograft combined with iliac crest aspirate provided low nonunion (0%) and delayed union (3.1%) rates. Currently, iliac crest aspirate combined with allograft is the senior author’s preferred osteotomy graft. There are limited data in the literature regarding the use of PRP and/or bone marrow aspirate in HTO. A histologic and radiographic study evaluated openingwedge HTO patients who received allograft alone or allograft augmented either with PRP or with PRP combined with concentrated iliac crest aspirate. Improved early osteotomy healing was seen in the group that received PRP and the group that received PRP and iliac crest aspirate, but no differences were seen in overall osteotomy union rates when compared with allograft alone.19 D’Elia et al.20 compared HTO union rates in 25 patients who received either iliac crest bone autograft or PRP combined with bone marrow aspirate. Union occurred in 100% of the iliac crest bone
Fig 4. Postoperative pain, rated on visual analog scale (VAS), at final follow-up. Mild pain is defined as a VAS score of 0 to 3, with nonsteroidal anti-inflammatory drugs as needed. Moderate pain is defined as a VAS score of 4 to 6, with knee injections as needed. Severe pain is defined as a VAS score of 7 to 10, with opioids as needed or arthroplasty.
autograft group versus 91% of the PRP and bone marrow aspirate group. No difference in time to union was seen between groups. Aryee et al.21 found no advantage of PRP and bone substitute over unaugmented osteotomy at 1 year. Although there are limited data on PRP and iliac crest aspirate in the setting of medial opening-wedge HTO, several authors have investigated the effect of other graft types. Kuremsky et al.22 reported increased construct failure and nonunion in patients who received corticocancellous allograft compared with iliac crest autograft. They also found that lateral cortical breach increased the failure rate, similar to our findings in which lateral cortical fracture was associated with the need for repeat surgery. A recent systematic review found that autograft provides lower delayed union and nonunion rates than other opening-wedge osteotomy fillers.23 In contrast, Cho et al.24 noted no difference in outcomes between iliac crest autograft and cancellous chip allograft. Yacobucci and Cocking25 reported a relatively low (4%) nonunion rate using corticocancellous wedge allograft. Miller et al.26 similarly found no difference in delayed union or nonunion rates between autograft and allograft. Although not specifically stated, it appears that a plate with limited distal fixation was used in 6 of 7 patients who lost correction in their study. A recent
Fig 5. Kaplan-Meier curve for arthroplasty-free high tibial osteotomy survival.
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Table 2. Concomitant Cartilage, Meniscus, and Ligament Surgery Pathology Medial meniscal deficiency PCL and PLC ligamentous injury
Treatment HTO, concomitant medial meniscus allograft HTO, staged PCL and PLC reconstruction
MFC OCD
HTO, synthetic plug and osteochondral autograft transfer HTO, microfracture HTO, microfracture
MFC OCD MFC OCD MFC OCD MFC OCD MFC OCD
HTO, osteochondral autograft transfer HTO, subchondral drilling HTO, open bone grafting and fixation of OCD lesion
Outcome Patient satisfied; occasional mild pain Patient satisfied; mild pain; returned to work climbing stairs and ladders without difficulty Patient satisfied; mild, intermittent pain Patient satisfied; mild pain Initial improvement, followed by progression to MFC avascular necrosis; subsequent arthroplasty Patient satisfied; mild pain Patient satisfied; minimal pain Continued moderate pain; rehabilitation complicated by symptomatic, contralateral knee OCD lesion
NOTE. The results of the 8 patients treated for focal medial cartilage defects, medial meniscal deficiency, or lateral ligamentous instability are shown. HTO, high tibial osteotomy; MFC, medial femoral condyle; OCD, osteochondral defect; PCL, posterior cruciate ligament; PLC, posterolateral corner.
study comparing osteotomy fixation with a short spacer plate (Aescula; B. Braun Korea, Seoul, Republic of Korea) and a rigid, long plate (TomoFix; Mathys, Bettlach, Switzerland) found higher rates of correction loss, malunion, and fixation failure with the small plate.27 These studies corroborate our results, in which plate size and screw fixation are important. In our study there were nonsignificant trends toward nonunion in female patients and smokers. Our study was likely underpowered, and prior authors have identified smoking as a risk factor for osteotomy nonunion or delayed union.28,29 Four osteotomies (4.5%) in our study lost coronal alignment. This is similar to the rate of coronal correction loss reported by Song et al.30 despite routine dual plating. Interestingly, we found an association between female gender and subsequent loss of coronal alignment. Bone mineral density studies were not routinely obtained, so we were unable to determine the role bone density may play in alignment loss. Lateral cortical fracture occurred in 5 of 89 cases (5.6%) in our study. This is slightly lower than the previously reported rates of 8% to 35%.26,31-34 We routinely direct our osteotomy just distal to the tip of the fibular head, which has been shown to decrease the risk of lateral cortical fracture.14 Although prior studies have shown an association between wedge size and lateral cortical fracture, we did not find this correlation.26,31 In our study lateral cortical fracture was associated with an increased rate of repeat surgery for nonunion and/or correction loss. This finding is consistent with clinical reports, as well as biomechanical data, that have shown decreased osteotomy stability in the setting of lateral cortical fracture.22,35 Although some authors have reported satisfactory alignment after percutaneous
lag screw fixation across the fractured lateral cortical hinge,36,37 others have suggested that 1 lag screw may not provide sufficient stability.38-41 We postulated that medial opening-wedge HTO would provide satisfactory intermediate-term clinical outcomes for most patients. At a mean follow-up of 4.0 years, pain was minimal or mild in 65% of patients, moderate in 16%, and severe in 19%. Similar results have been reported by other studies.4,39,42 In our study, subjective pain outcomes were not associated with patient gender, smoking status, degree of mechanical axis correction, or final tibiofemoral angle. Patient BMI was marginally associated with increased postoperative pain (P ¼ .06). The effect of these variables on HTO outcomes is controversial.9,28,43,44 Only 1 patient in our study had postoperative alignment outside our desired range of 4 to 8 of valgus, so our study was likely underpowered to detect the influence of alignment on outcome. We found no association between patient age and subjective pain outcomes or the need for subsequent arthroplasty. This finding is corroborated by various other authors.7,28,43,45 However, some investigators have reported an association between older patient age and progression to arthroplasty.37,46 The study design often makes it difficult to account for potential selection bias, in which older patients may be more frequently offered conversion to arthroplasty. Seven patients (8%) in our study underwent arthroplasty at a mean of 5.0 years after osteotomy. This survivorship number is consistent with numbers reported by other authors.47-52 As expected, the need for arthroplasty was associated with longer follow-up periods.37 Surprisingly, osteotomy fixation with a smaller plate with only 4 screws was associated with increased postoperative pain even after correction for follow-up length
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Table 3. Focused Evaluation of Demographic Data and Preoperative and Intraoperative Findings in Patients Who Progressed to Arthroplasty Alignment Assessment of medial compartment on preoperative radiographs (Kellgren-Lawrence grade) Assessment of intercondylar notch and lateral compartment on preoperative radiographs Intraoperative assessment of medial compartment on arthroscopy (Outerbridge grade) Intraoperative assessment of lateral compartment on arthroscopy (Outerbridge grade) Mean patient age at osteotomy, yr Mean length of follow-up, yr
(the senior author predominantly used the smaller plate early in the study). Small-plate fixation was also associated with the need for subsequent arthroplasty, but we were unable to statistically correct for follow-up length given the relatively number of arthroplasty events. However, the osteotomy fixation method was clearly important in our series: The use of a smaller plate with fewer screws was associated with increased postoperative pain, nonunion, and conversion to arthroplasty. We closely evaluated the clinical, radiologic, and arthroscopic data for our 7 patients who underwent arthroplasty, and these data are summarized in Table 3. When we looked critically at pre-osteotomy radiographs, the majority (6 of 7) had lateral rim or intercondylar notch osteophytes. Although only 1 patient had grade 4 Kellgren-Lawrence arthritic changes on radiographs, 5 of 7 had grade 4 changes in the medial compartment at arthroscopy. Most patients (6 of 7) also had large medial meniscal tears at arthroscopy, consistent with data suggesting that patients with medial meniscal injury are at increased risk of subsequent arthroplasty.48 Interestingly, arthroscopic evaluation of the lateral compartment did not forebode subsequent arthroplasty: Only 1 patient had a lateral meniscal tear, and 1 patient had grade 1 cartilage changes laterally. In our study better outcomes in terms of postoperative pain and the need for arthroplasty or revision, non-elective surgery were seen among the subgroup of 29 patients who received iliac crest aspirate and underwent osteotomy fixation with larger plates. When compared with the rest of the osteotomy patients, this subgroup had improved postoperative pain scores (P ¼ .01) and was less likely to undergo arthroplasty (P ¼ .05). These decreased pain scores remained significant even after correction for patient gender, BMI, and length of follow-up (P ¼ .03). A summary of these findings is shown in Table 4.
Data in Arthroplasty Group Preoperative, 3.1 of varus; postoperative, 6.4 of valgus Grade 2: 2 patients Grade 3: 4 patients Grade 4: 1 patient Notch or lateral rim osteophytes: 6 of 7 patients Grade 3 cartilage wear: 2 of 7 patients Grade 4 cartilage wear: 5 of 7 patients Large medial meniscal tear: 6 of 7 patients Normal: 5 of 7 patients Grade 1: 1 of 7 patients Lateral meniscal tear: 1 of 7 patients 51.1 (v 47.7 in patients who had not required arthroplasty at final follow-up, P ¼ .28) 6.0 (v 3.8 in non-arthroplasty group, P ¼ .02)
No nonunions occurred within the large plateeiliac crest aspirate subgroup, whereas 5 nonunions (8.3%) occurred in the rest of the patients. However, this difference in nonunion rate did not reach statistical significance (P ¼ .10). Limitations Our study has several limitations. First, as a retrospective study without a nonoperative control group for comparison, we are unable to assess how HTO affects the natural history of knee arthritis and the ultimate need for arthroplasty. However, study patients were offered surgery because they were incapacitated by pain and unable to function in their daily lives. A nonoperative control group in this setting would be unrealistic. Comparison with a group of patients treated with unicompartmental or total knee arthroplasty would also be informative. However, patients in this study were relatively young, high-demand individuals who wanted to preserve their native knee joints and avoid postoperative activity restrictions. These patient desires, as well as surgeon concern for potentially increased implant wear in this population, would complicate treatment allocation. The senior author varied osteotomy fixation and graft type throughout the course of the study in a nonrandom fashion, with later patients undergoing fixation with a large plate and receiving allograft combined with iliac crest aspirate. Although the senior author did not otherwise vary his surgical technique throughout the study, this does introduce the possibility of selection bias. Our study would ideally include both coronal and sagittal alignment data. However, some radiographs were lost during transition to an electronic medical record. Although coronal osteotomy alignment was meticulously documented in the senior author’s clinical notes, which were transferred to the electronic system,
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Table 4. Large PlateeIliac Crest Aspirate Subgroup Analysis Demographic data Female gender BMI, kg/m2 Follow-up period, yr Age, yr Preoperative alignment Postoperative alignment Smoking status Outcomes Pain Nonunion Repeat, non-elective surgery Arthroplasty
Large PlateeIliac Crest Aspirate Recipients
Rest of Cohort
P Value
4 of 29 (15%) 29.8 2.2 48.6 3.3 of varus 6.7 of valgus 6 of 29 (21%)
23 of 60 (40%) 32.7 4.8 47.7 3.3 of varus 6.3 of valgus 11 of 60 (18%)
.02 .02 .001 .64 .86 .24 .79
None/mild, 81%; moderate, 15%; severe, 4% 0 of 29 (0%) 1 of 29 (3.4%) 0 of 29 (0%)
None/mild, 56%; moderate, 18.2%; severe, 25.5% 5 of 60 (8%) 16 of 60 (26.7%) 7 of 60 (12%)
.01, .03 corrected* .10 .009, .03 corrected* .05y
BMI, body mass index. *After correction for differences between groups in patient gender, BMI, and follow-up length. y Unable to statistically correct for potential confounders of patient gender, BMI, and follow-up length.
sagittal measurements were inconsistently recorded. Although it is plausible that larger plates better maintain sagittal osteotomy alignment and this may contribute to improved outcomes, we lack the requisite data to evaluate the effect of sagittal alignment on clinical outcomes. Our study group is heterogeneous. Although HTO was performed in most patients to offload an arthritic medial compartment, 8 osteotomies were performed in conjunction with other treatment for focal medial osteochondral defects, medial meniscal deficiency, or lateral ligamentous instability. With the relatively small numbers available, subgroup analysis of these 8 patients was not possible. Statistical analysis of our study group was underpowered by relatively low numbers of nonunion and arthroplasty events. Specifically, although nonunion did not occur in any of the 29 patients who received iliac crest aspirate plus allograft and underwent osteotomy fixation with a large plate, our data were underpowered to detect a difference in nonunion rates between these patients and the remainder of the group. Furthermore, although a lower rate of arthroplasty was noted in this subgroup, multivariate analysis to correct for follow-up length was underpowered because of the low numbers of arthroplasty events overall. In additional to statistical limitations, we did not document functional outcomes. Although we maintain that subjective pain scores and the need for repeat surgery and/or arthroplasty remain the most important outcomes, ideally, preoperative and postoperative function would also be reported through validated outcome measures. The main limitation of this study was the follow-up period, with minimum and mean follow-up periods of 1 year and 4 years, respectively.
Although useful information is provided regarding osteotomy union, maintenance of alignment, and early pain relief, it is likely that with increased follow-up, more patients will require conversion to arthroplasty.
Conclusions Uncomplicated union occurred in 83 of 89 medial opening-wedge HTOs (93%). Allograft mixed with PRP and/or DBM was associated with nonunion. At intermediate follow-up, 65% of patients had minimal or mild pain. Seven patients (8%) had undergone arthroplasty. Fixation with a smaller plate was associated with increased postoperative pain and the need for subsequent arthroplasty.
Acknowledgment The authors thank and acknowledge Annabeth McLendon for her assistance with data acquisition and manuscript preparation.
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osteotomy and microfracture. J Knee Surg 2007;20: 129-133. Birmingham TB, Giffin JR, Chesworth BM, et al. Medial opening wedge high tibial osteotomy: A prospective cohort study of gait, radiographic, and patient-reported outcomes. Arthritis Rheum 2009;61:648-657. McNamara IR, Birmingham TB, Marsh JD, Chesworth BM, Bryant DM, Giffin JR. A preference-based single-item measure of quality of life following medial opening wedge high tibial osteotomy: Large improvements similar to arthroplasty. Knee 2014;21:456-461. Floerkemeier S, Staubli AE, Schroeter S, Goldhahn S, Lobenhoffer P. Outcome after high tibial open-wedge osteotomy: A retrospective evaluation of 533 patients. Knee Surg Sports Traumatol Arthrosc 2013;21:170-180. Koshino T, Wada S, Ara Y, Saito T. Regeneration of degenerated articular cartilage after high tibial valgus osteotomy for medial compartmental osteoarthritis of the knee. Knee 2003;10:229-236. Jung WH, Takeuchi R, Chun CW, et al. Second-look arthroscopic assessment of cartilage regeneration after medial opening-wedge high tibial osteotomy. Arthroscopy 2014;30:72-79. Wakabayashi S, Akizuki S, Takizawa T, Yasukawa Y. A comparison of the healing potential of fibrillated cartilage versus eburnated bone in osteoarthritic knees after high tibial osteotomy: An arthroscopic study with 1-year follow-up. Arthroscopy 2002;18:272-278. Smith TO, Sexton D, Mitchell P, Hing CB. Opening or closing wedged high tibial osteotomy: A meta-analysis of clinical and radiological outcomes. Knee 2011;18:361-368. Amendola A, Bonasia DE. Results of high tibial osteotomy: Review of the literature. Int Orthop 2010;34: 155-160. Dugdale TW, Noyes FR, Styer D. Preoperative planning for high tibial osteotomy. The effect of lateral tibiofemoral separation and tibiofemoral length. Clin Orthop Relat Res 1992;(274):248-264. Han SB, Lee DH, Shetty GM, Chae DJ, Song JG, Nha KW. A “safe zone” in medial open-wedge high tibial osteotomy to prevent lateral cortex fracture. Knee Surg Sports Traumatol Arthrosc 2013;21:90-95. Kim J, Allaire R, Harner CD. Vascular safety during high tibial osteotomy: A cadaveric angiographic study. Am J Sports Med 2010;38:810-815. El-Azab H, Halawa A, Anetzberger H, Imhoff AB, Hinterwimmer S. The effect of closed- and open-wedge high tibial osteotomy on tibial slope. J Bone Joint Surg Br 2008;90:1193-1197. Marti CB, Gautier E, Wachtl SW, Jakob RP. Accuracy of frontal and sagittal plane correction in open-wedge high tibial osteotomy. Arthroscopy 2004;20:366-372. Wang JH, Bae JH, Lim HC, Shon WY, Kim CW, Cho JW. Medial open wedge high tibial osteotomy: The effect of the cortical hinge on posterior slope. Am J Sports Med 2009;37:2411-2418. Dallari D, Savarino L, Stagni C, et al. Enhanced tibial osteotomy healing with use of bone grafts supplemented with platelet gel or platelet gel and bone marrow stromal cells. J Bone Joint Surg Am 2007;89:2413-2420.
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20. D’Elia CO, Rezende MU, Bitar AC, et al. Comparison between platelet-rich plasma and autologous iliac grafts for tibial osteotomy. Cartilage 2010;1:320-327. 21. Aryee S, Imhoff AB, Rose T, Tischer T. Do we need synthetic osteotomy augmentation materials for opening-wedge high tibial osteotomy. Biomaterials 2008;29:3497-3502. 22. Kuremsky MA, Schaller TM, Hall CC, Roehr BA, Masonis JL. Comparison of autograft vs allograft in opening-wedge high tibial osteotomy. J Arthroplasty 2010;25:951-957. 23. Lash NJ, Feller JA, Batty LM, Wasiak J, Richmond AK. Bone grafts and bone substitutes for opening-wedge osteotomies of the knee: A systematic review. Arthroscopy 2015;31:720-730. 24. Cho SW, Kim DH, Lee GC, Lee SH, Park SH. Comparison between autogenous bone graft and allogenous cancellous bone graft in medial open wedge high tibial osteotomy with 2-year follow-up. Knee Surg Relat Res 2013;25:117-125. 25. Yacobucci GN, Cocking MR. Union of medial openingwedge high tibial osteotomy using corticocancellous proximal tibial wedge allograft. Am J Sports Med 2008;36: 713-719. 26. Miller BS, Downie B, McDonough EB, Wojtys EM. Complications after medial opening wedge high tibial osteotomy. Arthroscopy 2009;25:639-646. 27. Jung WH, Chun CW, Lee JH, Ha JH, Kim JH, Jeong JH. Comparative study of medial opening-wedge high tibial osteotomy using 2 different implants. Arthroscopy 2013;29: 1063-1071. 28. Van Houten AH, Heesterbeek PJ, van Heerwaarden RJ, van Tienen TG, Wymenga AB. Medial open wedge high tibial osteotomy: Can delayed or nonunion be predicted? Clin Orthop Relat Res 2014;472:1217-1223. 29. Niemeyer P, Koestler W, Kaehny C, et al. Two-year results of open-wedge high tibial osteotomy with fixation by medial plate fixator for medial compartment arthritis with varus malalignment of the knee. Arthroscopy 2008;24: 796-804. 30. Song EK, Seon JK, Park SJ, Jeong MS. The complications of high tibial osteotomy: Closing versus opening-wedge methods. J Bone Joint Surg Br 2010;92:1245-1252. 31. Takeuchi R, Ishikawa H, Kumagai K, et al. Fractures around the lateral cortical hinge after a medial openingwedge high tibial osteotomy: A new classification of lateral hinge fracture. Arthroscopy 2013;28:85-94. 32. Hernigou P, Medevielle D, Debeyre J, Goutallier D. Proximal tibial osteotomy for osteoarthritis with varus deformity. A ten to thirteen-year follow-up study. J Bone Joint Surg Am 1987;69:332-354. 33. Van Raaij TM, Brouwer RW, de Vlieger R, Reijman M, Verhaar JA. Opposite cortical fracture in high tibial osteotomy: Lateral closing compared to the medial opening-wedge technique. Acta Orthop 2008;79:508-514. 34. Nelissen EM, van Langelaan EJ, Nelissen RGHH. Stability of medial opening wedge high tibial osteotomy: A failure analysis. Int Orthop 2010;34:217-223. 35. Miller BS, Dorsey WO, Bryant CR, Austin JC. The effect of lateral cortex disruption and repair on the stability of the medial opening wedge high tibial osteotomy. Am J Sports Med 2005;33:1552-1557.
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36. Paccola CAJ, Fogagnolo F. Open-wedge high tibial osteotomy: A technical trick to avoid loss of reduction of the opposite cortex. Knee Surg Sports Traumatol Arthrosc 2005;13:19-22. 37. Bonasia DE, Dettoni F, Sito G, et al. Medial opening wedge high tibial osteotomy for medial compartment overload/arthritis in the varus knee: Prognostic factors. Am J Sports Med 2014;42:690-698. 38. Kazimoglu C, Akdogan Y, Sener M, Kurtulmus A, Karapinar H, Uzun B. Which is the best fixation method for lateral cortex disruption in the medial open wedge high tibial osteotomy? A biomechanical study. Knee 2008;15:305-308. 39. Kolb W, Guhlmann H, Windisch C, Kolb K, Koller H, Grutzner P. Opening-wedge high tibial osteotomy with a locked low-profile plate. J Bone Joint Surg Am 2009;91: 2581-2588. 40. Kim MK, Ha JK, Lee DW, Nam SW, Kim JG, Lee YS. No correction angle loss with stable plates in open-wedge high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc in press, available online 30 January, 2014. doi:10.1007/ s00167-014-2842-7. 41. Agneskirchner JD, Freiling D, Hurschler C, Lobenhoffer P. Primary stability of four different implants for opening wedge high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 2006;14:291-300. 42. Salzmann GM, Ahrens P, Naal FD, et al. Sporting activity after high tibial osteotomy for the treatment of medial compartment knee osteoarthritis. Am J Sports Med 2009;37:312-318. 43. Spahn G, Kirschbaum S, Kahl E. Factors that influence high tibial osteotomy results in patients with medial gonarthrosis: A score to predict the results. Osteoarthritis Cartilage 2006;14:190-195. 44. El-Azab HM, Morgenstern M, Ahrens P, Schuster T, Imhoff AB, Lorenz SG. Limb alignment after open-wedge
45.
46.
47.
48.
49.
50.
51.
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high tibial osteotomy and its effect on the clinical outcome. Orthopedics 2011;34:e622-e628. Kohn L, Sauerschnig M, Iskansar S, et al. Age does not influence the clinical outcome after high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 2013;21: 146-151. Trieb K, Grohs J, Hanslik-Schnabel B, Stulnig T, Panotopoulos J, Wanivenhaus A. Age predicts outcome of high-tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 2006;14:149-152. DeMeo PJ, Johnson EM, Chiang PP, Flamm AM, Miller MC. Midterm follow-up of opening-wedge high tibial osteotomy. Am J Sports Med 2010;38:2077-2084. Sterett WI, Steadman JR, Huang MJ, Matheny LM, Briggs KK. Chondral resurfacing and high tibial osteotomy in the varus knee: Survivorship analysis. Am J Sports Med 2010;38:1420-1424. LaPrade RF, Spiridonov SI, Nystrom KM, Jansson KS. Prospective outcomes of young and middle-aged adults with medial compartment arthritis treated with a proximal tibial opening wedge osteotomy. Arthroscopy 2012;28: 354-364. Schallberger A, Jacobi M, Wahl P, Maestretti G, Jakob RP. High tibial valgus osteotomy in unicompartmental medial osteoarthritis of the knee: A retrospective follow-up study over 13-21 years. Knee Surg Sports Traumatol Arthrosc 2011;19:122-127. Niinimaki TT, Eskelinen A, Mann BS, Junnila M, Ohtonen P, Leppilahti J. Survivorship of high tibial osteotomy in the treatment of osteoarthritis of the knee: Finnish registry-based study of 3195 knees. J Bone Joint Surg Br 2012;94:1517-1521. Benzakour T, Hefti A, Lemseffer M, El Ahmadi JD, Bouyarmane H, Benzakour A. High tibial osteotomy for medial osteoarthritis of the knee: 15 years follow-up. Int Orthop 2010;34:209-215.
Purpose: We report intermediate-term outcomes of a large consecutive series of medial opening-wedge tibial osteotomies. Methods: One hundred consecutive patients who underwent medial high tibial osteotomy from 2004-2013 were retrospectively reviewed. Charts were reviewed for patient age and gender, knee pain and range of motion, smoking status, and body mass index. Operative reports were reviewed for bone graft type, degree of correction, and osteotomy fixation method. Radiographs were evaluated for lateral cortical or intra-articular fracture, osteotomy healing, and preoperative and postoperative tibiofemoral angles. Results: Eighty-nine osteotomies (89%) in 83 patients were included in the study. Most procedures were performed for medial knee arthritis. The mean age at surgery was 48.1 years, and the mean follow-up period was 4.0 years. The mean tibiofemoral alignment was 3.2 of varus preoperatively and 6.4 of valgus postoperatively. Plate and screw fixation was used in all cases. Bone grafting methods included autograft, allograft, iliac crest aspirate, platelet-rich plasma, and demineralized bone matrix. Of the osteotomies, 83 (93%) healed uneventfully. Five nonunions and 1 delayed union occurred. Allograft combined with demineralized bone matrix and/or platelet-rich plasma was associated with nonunion (P ¼ .02). Lateral cortical fracture was associated with repeat surgery for nonunion or alignment loss (P ¼ .02). Pain was minimal or mild in 65% of patients, moderate in 16%, and severe in 19%. Osteotomy fixation with a small 4-screw plate was associated with increased postoperative pain (P ¼ .01). Seven patients underwent arthroplasty an average of 5 years after osteotomy. The need for arthroplasty was associated with longer follow-up (P ¼ .02) and use of a smaller plate (P ¼ .04). Conclusions: Uncomplicated osteotomy union occurred in 93% of medial opening-wedge high tibial osteotomies. Allograft mixed with demineralized bone matrix and/or plateletrich plasma was associated with nonunion. At intermediate follow-up, 65% of patients had minimal or mild pain. Seven patients had undergone arthroplasty. Fixation with a smaller plate was associated with increased postoperative pain and the need for subsequent arthroplasty. Level of Evidence: Level IV, therapeutic case series.
H
igh tibial osteotomy (HTO) is a surgical option for the treatment of varus gonarthrosis or varus malalignment with coexisting medial chondral defects, medial meniscal deficiency, or lateral ligamentous insufficiency. HTO is particularly indicated for the treatment of unicompartmental degenerative arthritis
From Mississippi Sports Medicine and Orthopaedic Center (S.A.G., W.R.S.), and the Department of Family Medicine, University of Mississippi Medical Center (W.H.R.), Jackson, Mississippi, U.S.A. Presented at the Spring Arthroscopy Association of North America Annual Meeting, Hollywood, FL, May, 2014. The authors report the following potential conflict of interest or source of funding: W.R.S. is chair of the Physicians Surgery Center, and he receives royalties as a consultant for Smith & Nephew. Received July 19, 2014; accepted April 30, 2015. Address correspondence to Walter R. Shelton, M.D., Mississippi Sports Medicine and Orthopaedic Center, 1325 E Fortification St, Jackson, MS 39202, U.S.A. E-mail: [email protected] Ó 2015 by the Arthroscopy Association of North America 0749-8063/14631/$36.00 http://dx.doi.org/10.1016/j.arthro.2015.04.097
in the young, active patient in whom implant arthroplasty may not be ideal.1,2 Studies have shown that offloading an arthritic knee compartment can lead to symptomatic improvement and possibly cartilage regeneration.3-10 HTO can be performed through a lateral closingwedge or medial opening-wedge technique. The literature does not support the superiority of one technique over the other, and the choice is largely one of surgeon preference.11,12 Medial opening-wedge osteotomy allows the surgeon to avoid tibiofibular joint disruption, minimize the risk of peroneal nerve injury, and preserve tibial bone stock.2 Disadvantages include the need for a bone graft, increased risk of nonunion, and the possibility of loss of correction due to osteotomy collapse.1,2 Our study reports the intermediate-term outcomes of a large, single-center consecutive series of medial opening-wedge HTOs. The study goals were to determine the effect of bone graft type and fixation method on osteotomy union and maintenance of alignment, to
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assess clinical outcomes, and to analyze failures. We hypothesized that (1) use of a larger plate would improve union rates and decrease loss of correction, (2) union of the osteotomy would be enhanced by combining iliac crest bone marrow aspirate with allograft cancellous bone graft, and (3) medial openingwedge HTO would provide satisfactory intermediateterm clinical outcomes in most patients.
Methods After institutional review board approval, we retrospectively reviewed the results of all patients who underwent medial opening-wedge HTO by the senior author (W.R.S.) from 2004-2013. No patients were excluded. The primary indication for HTO was painful varus gonarthrosis in a young, active patient. Additional indications were varus malalignment with associated medial osteochondral defects, medial meniscal deficiency, or lateral ligamentous instability. The other parameters were as follows: patient age younger than 60 years, knee flexion contracture of less than 10 and knee flexion greater than 90 , medial-compartment radiographic degenerative changes that did not exceed Kellgren-Lawrence grade 3, and lateral-compartment cartilage status no worse than Outerbridge grade 2. Patient age and gender, knee pain and range of motion, smoking status, and body mass index (BMI) were documented along with bone graft type, osteotomy fixation method, and status of meniscal-chondral and ligamentous structures. Radiographs were evaluated to assess preoperative and postoperative tibiofemoral angles, intraoperative lateral cortical or intra-articular fracture, and osteotomy healing. The minimum follow-up period was set at 1 year. Statistical analysis was performed with c2 tests for associations between nominal predictors and outcomes and with independent t tests for nominal predictors and interval scaled outcomes. A Kaplan-Meier curve was constructed to illustrate arthroplasty-free HTO survival. An a level of .05 was used to determine statistical significance. For primary outcome measures, such as union versus nonunion, the study was powered to detect an event rate of a binary predictor of 20%. Multivariate analysis was performed when relevant, except when low outcome numbers precluded such analysis. Surgical Technique Preoperative template planning is performed according to the method of Dugdale et al.13 After tourniquet inflation, diagnostic arthroscopy is performed to document medial-compartment arthritis and to assess the status of the lateral and patellofemoral compartments and menisci. An anteromedial skin incision is made along the proximal tibia and carried through the sartorial fascia to the pes tendons, which are retracted
posteriorly. A Chandler retractor is placed subperiosteally around the posterior tibial cortex to protect the posterior neurovascular structures. The patellar tendon is identified and retracted anteriorly. A guide pin is inserted along the template-determined osteotomy line, which is made proximal to the tibial tubercle starting medially along the metaphyseal flare and aiming laterally toward the fibular head.14 A saw is used to cut the medial cortex of the tibial shaft to a depth of 2 cm along the guide pin. The knee is placed in 90 of flexion, and the posterior cut is made with a wide calibrated osteotome to within 10 mm of the lateral tibial cortex, thus avoiding lateral cortical disruption.15 The anterior osteotome cut is made with the knee extended and the patellar tendon retracted. Calibrated wedges are used to open the osteotomy to the desired mechanical axis correction. Care is taken to preserve the posterior tibial slope, and the anterior osteotomy gap is routinely two-thirds the posterior gap.16-18 The tourniquet is deflated before bone grafting and plate fixation to confirm the integrity of the popliteal vasculature. Bone graft is impacted into the osteotomy site. For the first 47 osteotomies in the series, various bone grafts were used, including allograft, allograft with demineralized bone matrix (DBM), allograft with platelet-rich plasma (PRP), and iliac crest autograft. Starting with osteotomy 48, all subsequent patients received cancellous allograft combined with 20 mL of autogenous iliac crest aspirate. An appropriatelysized Arthrex wedge plate (Arthrex, Naples, FL) is used to fix the osteotomy. A separate lateral lag screw is placed from proximal-medial to distal-lateral to prevent late unhinging of the lateral osteotomy site. Fluoroscopy is used to confirm correction of the mechanical axis according to the preoperative template. Patients are restricted to toe-touch weight bearing until 6 weeks, at which time progressive weight bearing is initiated if radiographs show evidence of healing. Figure 1 shows a typical postoperative radiograph.
Results Minimum 1-year follow-up was available for 89 osteotomies (89%) in 83 patients. The mean patient age at osteotomy was 48.1 years, and the mean follow-up period was 4.0 years (range, 1.0 to 10.0 years). The mean weight-bearing alignment was 3.2 of varus preoperatively and 6.4 of valgus postoperatively. Uncomplicated osteotomy healing occurred in 83 of 89 osteotomies (93%). Five nonunions and 1 delayed union were noted. Nonunion occurred in 2 of 17 smokers (11.8%) versus 3 of 72 nonsmokers (4.2%) (P ¼ .22). There was a trend toward increased nonunion in female patients (3 of 27 [11.1%] v 2 of 62 male patients [3.2%]), but this did not reach statistical significance (P ¼ .14). Patient
OPENING-WEDGE HIGH TIBIAL OSTEOTOMY
Fig 1. Typical radiograph of a left knee showing plate and screw fixation immediately postoperatively. The prophylactic “lock-down” lag screw across the lateral osteotomy hinge should be noted.
age and BMI were not associated with nonunion (P ¼ .65 and P ¼ .71, respectively). The first 47 osteotomies in this series were fixed with a small 4-screw plate and multiple types of bone graft (allograft plus DBM, n ¼ 21; allograft plus PRP, n ¼ 13; allograft alone, n ¼ 10; and iliac crest autograft, n ¼ 3). Nonunion in this group was problematic (5 of 47). All 5 nonunions occurred in the allograft-plus-DBM (n ¼ 3) and allograft-plus-PRP (n ¼ 2) groups (P ¼ .02) and with the use of a small plate (P ¼ .09). In an attempt to improve the results, the senior author made 2 significant changes in technique. Starting with osteotomy 48, subsequent patients (42) underwent bone grafting with cancellous allograft combined with 20 mL of autogenous iliac crest aspirate. Starting with patient 59, all subsequent osteotomies (31) underwent fixation with a large plate using 3 screws proximally and 3 screws distally. No nonunion occurred with the use of allograft
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plus iliac crest aspirate or with the use of a larger plate. Figures 2 and 3 show the relation between osteotomy union and plate and graft type. Four patients had loss of coronal alignment. Nonunion did not develop in any of these patients. One had an intraoperative lateral cortical fracture fixed with a lag screw outside of the plate but lost correction despite this fixation. The other 3 patients lost alignment despite use of prophylactic lag screws across the lateral osteotomy hinge. Two of these 3 patients lost correction after falls, and another lost alignment on returning to heavy mechanic work 3 months postoperatively. Two of the 4 patients who lost coronal alignment underwent revision osteotomy fixation and uneventfully healed in terms of desired valgus alignment. Another patient sustained a fall after hardware removal and had a fracture through the osteotomy site. She was successfully treated with closed reduction and casting. The remaining patient declined revision osteotomy. Female gender was associated with subsequent loss of coronal alignment (P ¼ .05). The amount of intraoperative coronal axis correction (P ¼ .53) was not associated with subsequent loss of coronal alignment, nor was patient BMI (P ¼ .61) or smoking status (P ¼ .11). Neither bone graft (P ¼ .32) nor plate type (P ¼ .67) was associated with correction loss. Because lateral lag screws were used in all but 3 patients, we were unable to statistically evaluate how these screws affected maintenance of alignment. Five patients had intraoperative lateral cortical fractures, all of which underwent lag screw fixation. One progressed to nonunion. Another lost coronal alignment, as described earlier. The trend toward nonunion in the setting of lateral cortical fracture was not significant (P ¼ .18). Loss of correction occurred in 3 of 84 osteotomies (3.6%) with an intact lateral cortex compared with 1 of 5 (20%) with a lateral cortical fracture. This trend was marginally significant (P ¼ .08). However, lateral cortical fracture was significantly associated with the need for repeat surgery for alignment loss or nonunion (P ¼ .02). Table 1 shows the relation between lateral cortical fracture and osteotomy union, maintenance of alignment, and the need for repeat surgery. Nondisplaced intra-articular fractures occurred in 6 patients. None of these intra-articular fractures or their associated osteotomies progressed to nonunion. Older age was associated with intra-articular fracture (P ¼ .04), whereas gender was not (P ¼ .45). Intraarticular fracture was not associated with increased postoperative pain (P ¼ .56) or the need for repeat surgery (P ¼ .82). No association was seen between intra-articular fracture and plate (P ¼ .51) or graft (P ¼ .42) type or degree of intraoperative correction (P ¼ .49).
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lateral ligamentous instability. Table 2 shows the pathology, treatment, and outcomes of these patients.
Fig 2. Osteotomy union rate categorized by high tibial osteotomy fixation method (P ¼ .09): plate with 2 proximal and 2 distal screws (2þ2 Plate) and plate with 3 proximal and 3 distal screws (3þ3 Plate).
Postoperative visual analog scale pain values were specifically documented for 82 of 89 osteotomies (92%) at the time of final follow-up. Patient age, patient gender, degree of mechanical axis correction, graft type, and final tibiofemoral alignment were not associated with subjective patient pain scores (P ¼ .92, P ¼ .43, P ¼ .99, P ¼ .18, and P ¼ .86, respectively). No association was seen between smoking status (P ¼ .73) or nonunion (P ¼ .16) and postoperative pain. Osteotomy fixation with a smaller plate with 2 proximal and 2 distal screws was associated with increased postoperative pain (P ¼ .001). This association remained significant (P ¼ .03) even after correction for length of follow-up and patient BMI, which was marginally associated with increased postoperative pain (P ¼ .06). Visual analog scale pain outcomes are shown in Figure 4. Seven patients underwent arthroplasty a mean of 5 years (range, 1.0 to 8.7 years) after the index osteotomy. The mean age at osteotomy for patients who went on to undergo arthroplasty was 51.1 years, as compared with 47.7 years for those who did not require arthroplasty. This was not statistically significant (P ¼ .28). Similarly, patient gender, BMI, smoking status, and graft type were not associated with subsequent arthroplasty (P ¼ .92, P ¼ .74, P ¼ .61, and P ¼ .18, respectively). The need for arthroplasty was associated with a longer follow-up time, with a mean follow-up time of 6.0 years in the arthroplasty group versus 3.8 years in patients who did not require arthroplasty (P ¼ .02). Use of a smaller plate was also associated with the need for subsequent arthroplasty (P ¼ .04). Arthroplasty-free osteotomy survival is shown in Figure 5. Eight osteotomies were performed to treat focal medial cartilage defects, medial meniscal deficiency, or
Complications Six patients had mild (mean, 4 ) loss of knee extension. Three patients had knee flexion loss, with 2 of these unable to flex their knees beyond 90 . Four patients required intravenous antibiotics for cellulitis. No patient required operative debridement for infection or hematoma. A nonfatal pulmonary embolism occurred 2 months after osteotomy in 1 patient, and a lower extremity deep venous thrombosis developed in another patient. One patient had a popliteal artery thrombosis at 5 days postoperatively and underwent vascular surgery. Fortunately, this patient recovered and had no residual neurovascular deficits. Overall, 25 patients (28%) underwent further surgery related to the index osteotomy. Excluding elective hardware removal, which comprised most cases, 15 of 88 patients (17%) required subsequent surgery. Five patients underwent surgery for nonunion, and 2 underwent revision fixation for loss of coronal alignment. As described earlier, 1 patient underwent vascular surgery. Arthroplasty was required in 7 patients.
Discussion Nonunion rates varied significantly according to osteotomy graft type. Allograft mixed with DBM and/or
Fig 3. High tibial osteotomy union rate according to graft type. Allograft (Allo) plus platelet-rich plasma (PRP) and allograft plus PRP and demineralized bone matrix (DBM) were associated with nonunion (P ¼ .02). (ICA, iliac crest aspirate; ICBG, iliac crest bone graft.)
OPENING-WEDGE HIGH TIBIAL OSTEOTOMY
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Table 1. Lateral Cortical Fracture Intact lateral cortex Lateral cortical fracture
Nonunion 4 of 84 (4.8%) 1 of 5 (20%)
Coronal Alignment Loss 3 of 84 (3.6%) 1 of 5 (20%)
Nonunion or Alignment Loss 7 of 84 (8.3%) 2 of 5 (40%)
NOTE. An association was found between lateral cortical fracture and osteotomy nonunion (P ¼ .18) and between lateral cortical fracture and coronal alignment loss (P ¼ .08). In addition, lateral cortical fracture was associated with revision surgery for nonunion or alignment loss (P ¼ .02).
PRP was associated with an increased nonunion rate (P ¼ .02). Allograft combined with iliac crest aspirate provided low nonunion (0%) and delayed union (3.1%) rates. Currently, iliac crest aspirate combined with allograft is the senior author’s preferred osteotomy graft. There are limited data in the literature regarding the use of PRP and/or bone marrow aspirate in HTO. A histologic and radiographic study evaluated openingwedge HTO patients who received allograft alone or allograft augmented either with PRP or with PRP combined with concentrated iliac crest aspirate. Improved early osteotomy healing was seen in the group that received PRP and the group that received PRP and iliac crest aspirate, but no differences were seen in overall osteotomy union rates when compared with allograft alone.19 D’Elia et al.20 compared HTO union rates in 25 patients who received either iliac crest bone autograft or PRP combined with bone marrow aspirate. Union occurred in 100% of the iliac crest bone
Fig 4. Postoperative pain, rated on visual analog scale (VAS), at final follow-up. Mild pain is defined as a VAS score of 0 to 3, with nonsteroidal anti-inflammatory drugs as needed. Moderate pain is defined as a VAS score of 4 to 6, with knee injections as needed. Severe pain is defined as a VAS score of 7 to 10, with opioids as needed or arthroplasty.
autograft group versus 91% of the PRP and bone marrow aspirate group. No difference in time to union was seen between groups. Aryee et al.21 found no advantage of PRP and bone substitute over unaugmented osteotomy at 1 year. Although there are limited data on PRP and iliac crest aspirate in the setting of medial opening-wedge HTO, several authors have investigated the effect of other graft types. Kuremsky et al.22 reported increased construct failure and nonunion in patients who received corticocancellous allograft compared with iliac crest autograft. They also found that lateral cortical breach increased the failure rate, similar to our findings in which lateral cortical fracture was associated with the need for repeat surgery. A recent systematic review found that autograft provides lower delayed union and nonunion rates than other opening-wedge osteotomy fillers.23 In contrast, Cho et al.24 noted no difference in outcomes between iliac crest autograft and cancellous chip allograft. Yacobucci and Cocking25 reported a relatively low (4%) nonunion rate using corticocancellous wedge allograft. Miller et al.26 similarly found no difference in delayed union or nonunion rates between autograft and allograft. Although not specifically stated, it appears that a plate with limited distal fixation was used in 6 of 7 patients who lost correction in their study. A recent
Fig 5. Kaplan-Meier curve for arthroplasty-free high tibial osteotomy survival.
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Table 2. Concomitant Cartilage, Meniscus, and Ligament Surgery Pathology Medial meniscal deficiency PCL and PLC ligamentous injury
Treatment HTO, concomitant medial meniscus allograft HTO, staged PCL and PLC reconstruction
MFC OCD
HTO, synthetic plug and osteochondral autograft transfer HTO, microfracture HTO, microfracture
MFC OCD MFC OCD MFC OCD MFC OCD MFC OCD
HTO, osteochondral autograft transfer HTO, subchondral drilling HTO, open bone grafting and fixation of OCD lesion
Outcome Patient satisfied; occasional mild pain Patient satisfied; mild pain; returned to work climbing stairs and ladders without difficulty Patient satisfied; mild, intermittent pain Patient satisfied; mild pain Initial improvement, followed by progression to MFC avascular necrosis; subsequent arthroplasty Patient satisfied; mild pain Patient satisfied; minimal pain Continued moderate pain; rehabilitation complicated by symptomatic, contralateral knee OCD lesion
NOTE. The results of the 8 patients treated for focal medial cartilage defects, medial meniscal deficiency, or lateral ligamentous instability are shown. HTO, high tibial osteotomy; MFC, medial femoral condyle; OCD, osteochondral defect; PCL, posterior cruciate ligament; PLC, posterolateral corner.
study comparing osteotomy fixation with a short spacer plate (Aescula; B. Braun Korea, Seoul, Republic of Korea) and a rigid, long plate (TomoFix; Mathys, Bettlach, Switzerland) found higher rates of correction loss, malunion, and fixation failure with the small plate.27 These studies corroborate our results, in which plate size and screw fixation are important. In our study there were nonsignificant trends toward nonunion in female patients and smokers. Our study was likely underpowered, and prior authors have identified smoking as a risk factor for osteotomy nonunion or delayed union.28,29 Four osteotomies (4.5%) in our study lost coronal alignment. This is similar to the rate of coronal correction loss reported by Song et al.30 despite routine dual plating. Interestingly, we found an association between female gender and subsequent loss of coronal alignment. Bone mineral density studies were not routinely obtained, so we were unable to determine the role bone density may play in alignment loss. Lateral cortical fracture occurred in 5 of 89 cases (5.6%) in our study. This is slightly lower than the previously reported rates of 8% to 35%.26,31-34 We routinely direct our osteotomy just distal to the tip of the fibular head, which has been shown to decrease the risk of lateral cortical fracture.14 Although prior studies have shown an association between wedge size and lateral cortical fracture, we did not find this correlation.26,31 In our study lateral cortical fracture was associated with an increased rate of repeat surgery for nonunion and/or correction loss. This finding is consistent with clinical reports, as well as biomechanical data, that have shown decreased osteotomy stability in the setting of lateral cortical fracture.22,35 Although some authors have reported satisfactory alignment after percutaneous
lag screw fixation across the fractured lateral cortical hinge,36,37 others have suggested that 1 lag screw may not provide sufficient stability.38-41 We postulated that medial opening-wedge HTO would provide satisfactory intermediate-term clinical outcomes for most patients. At a mean follow-up of 4.0 years, pain was minimal or mild in 65% of patients, moderate in 16%, and severe in 19%. Similar results have been reported by other studies.4,39,42 In our study, subjective pain outcomes were not associated with patient gender, smoking status, degree of mechanical axis correction, or final tibiofemoral angle. Patient BMI was marginally associated with increased postoperative pain (P ¼ .06). The effect of these variables on HTO outcomes is controversial.9,28,43,44 Only 1 patient in our study had postoperative alignment outside our desired range of 4 to 8 of valgus, so our study was likely underpowered to detect the influence of alignment on outcome. We found no association between patient age and subjective pain outcomes or the need for subsequent arthroplasty. This finding is corroborated by various other authors.7,28,43,45 However, some investigators have reported an association between older patient age and progression to arthroplasty.37,46 The study design often makes it difficult to account for potential selection bias, in which older patients may be more frequently offered conversion to arthroplasty. Seven patients (8%) in our study underwent arthroplasty at a mean of 5.0 years after osteotomy. This survivorship number is consistent with numbers reported by other authors.47-52 As expected, the need for arthroplasty was associated with longer follow-up periods.37 Surprisingly, osteotomy fixation with a smaller plate with only 4 screws was associated with increased postoperative pain even after correction for follow-up length
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7
Table 3. Focused Evaluation of Demographic Data and Preoperative and Intraoperative Findings in Patients Who Progressed to Arthroplasty Alignment Assessment of medial compartment on preoperative radiographs (Kellgren-Lawrence grade) Assessment of intercondylar notch and lateral compartment on preoperative radiographs Intraoperative assessment of medial compartment on arthroscopy (Outerbridge grade) Intraoperative assessment of lateral compartment on arthroscopy (Outerbridge grade) Mean patient age at osteotomy, yr Mean length of follow-up, yr
(the senior author predominantly used the smaller plate early in the study). Small-plate fixation was also associated with the need for subsequent arthroplasty, but we were unable to statistically correct for follow-up length given the relatively number of arthroplasty events. However, the osteotomy fixation method was clearly important in our series: The use of a smaller plate with fewer screws was associated with increased postoperative pain, nonunion, and conversion to arthroplasty. We closely evaluated the clinical, radiologic, and arthroscopic data for our 7 patients who underwent arthroplasty, and these data are summarized in Table 3. When we looked critically at pre-osteotomy radiographs, the majority (6 of 7) had lateral rim or intercondylar notch osteophytes. Although only 1 patient had grade 4 Kellgren-Lawrence arthritic changes on radiographs, 5 of 7 had grade 4 changes in the medial compartment at arthroscopy. Most patients (6 of 7) also had large medial meniscal tears at arthroscopy, consistent with data suggesting that patients with medial meniscal injury are at increased risk of subsequent arthroplasty.48 Interestingly, arthroscopic evaluation of the lateral compartment did not forebode subsequent arthroplasty: Only 1 patient had a lateral meniscal tear, and 1 patient had grade 1 cartilage changes laterally. In our study better outcomes in terms of postoperative pain and the need for arthroplasty or revision, non-elective surgery were seen among the subgroup of 29 patients who received iliac crest aspirate and underwent osteotomy fixation with larger plates. When compared with the rest of the osteotomy patients, this subgroup had improved postoperative pain scores (P ¼ .01) and was less likely to undergo arthroplasty (P ¼ .05). These decreased pain scores remained significant even after correction for patient gender, BMI, and length of follow-up (P ¼ .03). A summary of these findings is shown in Table 4.
Data in Arthroplasty Group Preoperative, 3.1 of varus; postoperative, 6.4 of valgus Grade 2: 2 patients Grade 3: 4 patients Grade 4: 1 patient Notch or lateral rim osteophytes: 6 of 7 patients Grade 3 cartilage wear: 2 of 7 patients Grade 4 cartilage wear: 5 of 7 patients Large medial meniscal tear: 6 of 7 patients Normal: 5 of 7 patients Grade 1: 1 of 7 patients Lateral meniscal tear: 1 of 7 patients 51.1 (v 47.7 in patients who had not required arthroplasty at final follow-up, P ¼ .28) 6.0 (v 3.8 in non-arthroplasty group, P ¼ .02)
No nonunions occurred within the large plateeiliac crest aspirate subgroup, whereas 5 nonunions (8.3%) occurred in the rest of the patients. However, this difference in nonunion rate did not reach statistical significance (P ¼ .10). Limitations Our study has several limitations. First, as a retrospective study without a nonoperative control group for comparison, we are unable to assess how HTO affects the natural history of knee arthritis and the ultimate need for arthroplasty. However, study patients were offered surgery because they were incapacitated by pain and unable to function in their daily lives. A nonoperative control group in this setting would be unrealistic. Comparison with a group of patients treated with unicompartmental or total knee arthroplasty would also be informative. However, patients in this study were relatively young, high-demand individuals who wanted to preserve their native knee joints and avoid postoperative activity restrictions. These patient desires, as well as surgeon concern for potentially increased implant wear in this population, would complicate treatment allocation. The senior author varied osteotomy fixation and graft type throughout the course of the study in a nonrandom fashion, with later patients undergoing fixation with a large plate and receiving allograft combined with iliac crest aspirate. Although the senior author did not otherwise vary his surgical technique throughout the study, this does introduce the possibility of selection bias. Our study would ideally include both coronal and sagittal alignment data. However, some radiographs were lost during transition to an electronic medical record. Although coronal osteotomy alignment was meticulously documented in the senior author’s clinical notes, which were transferred to the electronic system,
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Table 4. Large PlateeIliac Crest Aspirate Subgroup Analysis Demographic data Female gender BMI, kg/m2 Follow-up period, yr Age, yr Preoperative alignment Postoperative alignment Smoking status Outcomes Pain Nonunion Repeat, non-elective surgery Arthroplasty
Large PlateeIliac Crest Aspirate Recipients
Rest of Cohort
P Value
4 of 29 (15%) 29.8 2.2 48.6 3.3 of varus 6.7 of valgus 6 of 29 (21%)
23 of 60 (40%) 32.7 4.8 47.7 3.3 of varus 6.3 of valgus 11 of 60 (18%)
.02 .02 .001 .64 .86 .24 .79
None/mild, 81%; moderate, 15%; severe, 4% 0 of 29 (0%) 1 of 29 (3.4%) 0 of 29 (0%)
None/mild, 56%; moderate, 18.2%; severe, 25.5% 5 of 60 (8%) 16 of 60 (26.7%) 7 of 60 (12%)
.01, .03 corrected* .10 .009, .03 corrected* .05y
BMI, body mass index. *After correction for differences between groups in patient gender, BMI, and follow-up length. y Unable to statistically correct for potential confounders of patient gender, BMI, and follow-up length.
sagittal measurements were inconsistently recorded. Although it is plausible that larger plates better maintain sagittal osteotomy alignment and this may contribute to improved outcomes, we lack the requisite data to evaluate the effect of sagittal alignment on clinical outcomes. Our study group is heterogeneous. Although HTO was performed in most patients to offload an arthritic medial compartment, 8 osteotomies were performed in conjunction with other treatment for focal medial osteochondral defects, medial meniscal deficiency, or lateral ligamentous instability. With the relatively small numbers available, subgroup analysis of these 8 patients was not possible. Statistical analysis of our study group was underpowered by relatively low numbers of nonunion and arthroplasty events. Specifically, although nonunion did not occur in any of the 29 patients who received iliac crest aspirate plus allograft and underwent osteotomy fixation with a large plate, our data were underpowered to detect a difference in nonunion rates between these patients and the remainder of the group. Furthermore, although a lower rate of arthroplasty was noted in this subgroup, multivariate analysis to correct for follow-up length was underpowered because of the low numbers of arthroplasty events overall. In additional to statistical limitations, we did not document functional outcomes. Although we maintain that subjective pain scores and the need for repeat surgery and/or arthroplasty remain the most important outcomes, ideally, preoperative and postoperative function would also be reported through validated outcome measures. The main limitation of this study was the follow-up period, with minimum and mean follow-up periods of 1 year and 4 years, respectively.
Although useful information is provided regarding osteotomy union, maintenance of alignment, and early pain relief, it is likely that with increased follow-up, more patients will require conversion to arthroplasty.
Conclusions Uncomplicated union occurred in 83 of 89 medial opening-wedge HTOs (93%). Allograft mixed with PRP and/or DBM was associated with nonunion. At intermediate follow-up, 65% of patients had minimal or mild pain. Seven patients (8%) had undergone arthroplasty. Fixation with a smaller plate was associated with increased postoperative pain and the need for subsequent arthroplasty.
Acknowledgment The authors thank and acknowledge Annabeth McLendon for her assistance with data acquisition and manuscript preparation.
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