The Journal of Arthroplasty xxx (2013) xxx–xxx
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How Effective Is Multiple Needle Puncturing for Medial Soft Tissue Balancing During Total Knee Arthroplasty? A Cadaveric Study In Jun Koh, MD a, b, Dai-Soon Kwak, PhD c, Tae Kyun Kim, MD, PhD d, In Joo Park, MD a, b, Yong In, MD, PhD b, e a
Department of Orthopaedic Surgery, Uijeongbu St. Mary’s Hospital, Uijeongbu-si, Gyeonggi-do, Korea Department of Orthopaedic Surgery, The Catholic University of Korea College of Medicine, Seoul, Korea Catholic Institute for Applied Anatomy, The Catholic University of Korea College of Medicine, Seoul, Korea d Joint Reconstruction Center, Seoul National University Bundang Hospital, Seongnam-si, Gyeonggi-do, Korea e Department of Orthopaedic Surgery, Seoul St. Mary’s Hospital, Seoul, Korea b c
a r t i c l e
i n f o
Article history: Received 20 August 2013 Accepted 3 November 2013 Available online xxxx Keywords: multiple needle puncturing medial collateral ligament gap balancing varus total knee arthroplasty
a b s t r a c t We investigated the quantitative effect and risk factors for over-release during multiple needle puncturing (MNP) for medial gap balancing in varus total knee arthroplasty (TKA). Of the ten pairs of cadaveric knees, one knee from each pair was randomly assigned to undergo MNP in extension (E group), while the other knee underwent MNP in flexion (F group). The increased extension and 90° flexion gaps after every five needle punctures were measured until over-release occurred. The extension gap (b 4 mm) and the 90° flexion gap (b 6 mm) gradually increased in both groups. The 90° flexion gaps increased more selectively than did the extension gaps. MNP in the flexed knee, a narrow MCL, and severe osteoarthritis were associated with a smaller number of MNPs required to over-release. © 2013 Elsevier Inc. All rights reserved.
Restoration of proper limb alignment and achievement of adequate soft tissue balance are essential for successful total knee arthroplasty (TKA) [1–5]. In addition, inadequate soft tissue balancing after TKA can lead to early failure such as instability, wear and loosening [6,7]. Given the paramount importance of gap measurement, various techniques and instruments for gap balancing such as laminar spreader, spacer block, and trial component have been suggested. In addition, recently developed instrumented tensioners permit surgeons to assess gap balance with a constant joint distraction force [2,8,9], but no standard gap assessment technique has been established. Meanwhile, because most TKA candidates typically present with preoperative varus knee deformity [10–12], medial tightness which requires further medial soft tissue release for accurate balancing is commonly encountered despite adequate bone resection and preliminary soft tissue release. Traditionally, a gradual subperiosteal release of the superficial medial collateral ligament (MCL) has been carried out in this clinical scenario [1,13–18]. However, because precise gap balancing when using this method is technically demanding [6,19], the correction of moderate varus deformity, which requires a modest increase in the medial joint gap, remains challenging. In addition, it often leads to over-release of the The Conflict of Interest statement associated with this article can be found at http:// dx.doi.org/10.1016/j.arth.2013.11.004. ⁎ Reprint requests: Yong In, MD, PhD, Department of Orthopaedic Surgery, Seoul St. Mary’s Hospital, 222 Banpo-daero, Seocho-gu, Seoul (137-701), Korea.
superficial MCL, resulting in catastrophic instability. Therefore, medial soft tissue balancing with this method is usually dependent upon the surgeon’s experience. Recently, multiple needle puncturing (MNP) in the MCL, a version of the pie-crusting technique which comes from lateral soft tissue release in patients with valgus deformity [16,20,21], was reported to be an effective and safe technique for progressive correction of moderate varus deformity during TKA [22,23]. In those of previous studies, needle punctures were progressively increased until 2 to 4 mm of mediolateral joint laxity in extension or 2 to 6 mm at 90° flexion was obtained, and the mediolateral balance was assessed using maximal manual varus–valgus stress. In addition, MNP has been performed with the knee either in extension or in flexion depending on when tightness was observed. However, quantitative gap information after MNP has not been presented, only the final obtained mediolateral joint laxity. Therefore, there is lack of quantitative data on how each needle puncture increases the medial joint gap with application of a constant distraction force for joint opening and whether the extended or flexed knee position during MNP affects the increase in the extension and 90° flexion gaps. In addition, although over-release reportedly occurs in 5% of patients [22], the number of needle punctures required for over-release and the risk factors for over-release during MNP remain unclear. We therefore sought to determine the quantitative effects of MNP on medial extension and 90° flexion gaps, whether the amount of increase in extension and 90° flexion gaps differs depending on
0883-5403/0000-0000$36.00/0 – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.arth.2013.11.004
Please cite this article as: Koh IJ, et al, How Effective Is Multiple Needle Puncturing for Medial Soft Tissue Balancing During Total Knee Arthroplasty? A Cadaveric Study, J Arthroplasty (2013), http://dx.doi.org/10.1016/j.arth.2013.11.004
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whether the knee is in extension or flexion during MNP, and to identify the risk factors for over-release using MNP for medial soft tissue balancing during TKA. We hypothesized that both extension and 90° flexion gap would gradually increase after MNP and would selectively increase after MNP. We also hypothesized that several factors would predict fewer MNPs leading to over-release. Materials and Methods We used 10 pairs of knees in this study (20 fresh-frozen cadaveric knees; 10 female, 10 male; mean ± standard deviation age, 75 ± 9 years; height, 158 ± 8 cm; weight, 53 ± 14 kg). As the taut portion of MCL moves anteriorly with the knee in flexion and posteriorly in extension, for each cadaver, we randomly assigned one knee to the extension (E) group, in which needle punctures were performed with the knee in extension, and the other knee to the flexion (F) group, in which the punctures were carried out with the knee in 90° flexion. Knees with previous lower extremity surgery (including hip and ankle) or trauma, as evidenced by visual scar or deformities were excluded. We performed an a priori power analysis to determine the appropriate number of specimens required to detect a difference in the amount of increase in the medial joint gap after each of five needle punctures. Ten pairs of specimens were required to detect a 1-mm increase in gap at an alpha level of 0.05 and with a power of 80% using a two-sided test. All surgical procedures were performed by a single surgeon (one of the authors) using a standard posterior-stabilized prosthesis instrumentation system (Genesis II; Smith & Nephew, Memphis, TN, USA). After performing a standard midline skin incision and medial parapatellar arthrotomy, the patella was subluxed. Then, the anterior cruciate ligament and both menisci were excised. Resection of the distal femur was carried out using intramedullary instrumentation with a 6° valgus angle, and the posterior cruciate ligament was thoroughly removed from the femoral attachment site after anterior– posterior femoral resection. Next, proximal tibia resection was performed using extramedullary instrumentation to resect a 10-mm in thickness from the lateral plateau with a cutting angle of 90° to the tibial axis. Measurement of the medial extension and 90° flexion gaps was performed using a tensor device (B Braun-Aesculap, Tuttlingen, Germany) and scaled-force forceps (B Braun-Aesculap) (Fig. 1). The tensor device has a base plate that is placed onto the resected tibial surface and two independent top plates that are placed onto each of
Fig. 1. Photograph showing how the joint gaps were measured. After standard bone resection, the extension and 90° flexion gaps were measured using a tensor device with the application of a 200-N distraction force via the scaled forceps.
the medial and lateral resected femoral undersurfaces. In addition, it can be distracted and maintained separately and has two independent scales connected to each plate indicating the distance from the base plate to the top plate. The forceps include a scale (range, 50–250 N) that indicates the amount of force applied to the tensor device. The tip of the base plate and each of the top plates were placed perpendicular to both the resected tibial and femoral surfaces, and the tensor device was pushed into the joint as deeply as possible to prevent the top plates from bending. During measurement of the extension gap, the thigh and leg were supported by assistants to maintain full extension, and 90° flexion of the knee was maintained during the 90° flexion gap measurement. During every measurement, a 200-N force, as indicated by the forceps scale, was applied to both the medial and lateral top plates by an investigator (one of the authors), and the measurement in millimeters as read from the scale of the tensor device was recorded. MNP was performed in the medial soft tissue of the joint which was distracted by the tensor device with a 200-N distraction force (Fig. 2). A single surgeon (one of the authors) made the needle punctures with a standard 18-gauge aspiration needle at the tensest fibers as determined by digital palpation. The punctures were made every 3 to 5 mm in the proximodistal and anteroposterior directions, as described in previous studies [22,23]. The joint gap increase was reassessed after every five needle punctures using the tensor device with a 200-N distraction force. In the E group, the needle punctures were performed with the knee in extension (Fig. 2A), and in the F group, they were performed with the knee in 90° flexion (Fig. 2B). The needle puncturing was continued until “over-release” occurred in the medial soft tissue. Over-release was defined as the point at which the structural integrity of the medial soft tissue was disrupted and the end-point of the medial joint gap was not detectable despite application of a 250-N distraction force, due to loss of mechanical strength. In addition, we classified knees
Fig. 2. Photograph showing how needle puncturing was done in the extended knee (A) and the flexed knee (B). Maintaining joint distraction with a tensor device, the tensest fibers were identified by digital palpation and punctured with a standard 18-gauge aspiration needle.
Please cite this article as: Koh IJ, et al, How Effective Is Multiple Needle Puncturing for Medial Soft Tissue Balancing During Total Knee Arthroplasty? A Cadaveric Study, J Arthroplasty (2013), http://dx.doi.org/10.1016/j.arth.2013.11.004
I.J. Koh et al. / The Journal of Arthroplasty xxx (2013) xxx–xxx Table 1 Comparison of the Severity of OA and MCL Width in Each Group. Group E OA severitya Mild Moderate Severe MCL width (mm)b
Group F
Significance 1.000
50 20 30 15.3 (3.4)
50 20 30 16.0 (3.4)
0.648
OA, osteoarthritis; MCL, medial collateral ligament. a Data are presented as percentages; the severity of OA was graded as mild, moderate, or severe. b Data are presented as mean (SD).
into early (late) over-release groups when it occurred earlier (later) than the average number of MNPs required for over-release in this study.
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Information including the age, gender, weight, and height of each cadaveric specimen was collected by an investigator (one of the authors). The severity of osteoarthritis (OA) in each cadaveric specimen was graded as mild (no articular cartilaginous lesion), moderate (focal lesion), or severe (extensive lesion) after the arthrotomy. In addition, the width of the MCL was measured using calipers at the level of the joint line after bone resection with the knee in extension in the E group, and with the knee in flexion in the F group (Table 1). The primary outcome variable was the medial extension and the 90° flexion gap increase after every five needle punctures in both groups, and the secondary outcome variables were the number of MNPs leading to over-release and predictors for over-release. To determine the effectiveness of MNP on the medial joint gap, we compared each change in the medial extension and 90° flexion gaps
Fig. 3. The degree of each extension and 90° flexion gap increased significantly after every five needle punctures in the E group (A) and in the F group (B), with the exception of those between 15 and 20 needle punctures in the F group. Values with a significant difference (P b 0.05) are marked with an asterisk.
Please cite this article as: Koh IJ, et al, How Effective Is Multiple Needle Puncturing for Medial Soft Tissue Balancing During Total Knee Arthroplasty? A Cadaveric Study, J Arthroplasty (2013), http://dx.doi.org/10.1016/j.arth.2013.11.004
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I.J. Koh et al. / The Journal of Arthroplasty xxx (2013) xxx–xxx
Table 2 Comparison of the Gap Increase Between the Extension and 90° Flexion Gaps in Each Group.a Medial Gap Increase (mm) Group E Extension Gap
Number of MNPs
Mean
5 10 15 20 25
0.6 (0.5) 1.3 (0.5) 1.9 (0.3) 2.4 (0.5) 3.5 (0.5)
Range 0–1 1–2 1–2 2–3 3–4
Group F
90° Flexion Gap Mean 1.1 1.8 2.6 3.0 4.3
(0.7) (1.0) (1.4) (0.8) (0.8)
Extension Gap
Range
Significance
0–2 1–4 1–5 2–4 3–5
0.138 0.177 0.111 0.140 0.093
Mean 0.8 (0.6) 1.6 (0.5) 2.3 (0.5) 3.0 (1.4) N/A
Range 0–2 1–2 2–3 2–4
90° Flexion Gap Mean 2.3 3.1 3.8 5.5
(1.2) (1.1) (0.8) (0.7)
Range
Significance
1–4 2–5 3–5 5–6
0.009 0.008 0.007 0.126
MNP, multiple needle puncture. a Data are presented as mean (SD).
after every 5 needle punctures using the Wilcoxon signed-rank test. In addition, to determine whether the extension and 90° flexion gap increased selectively, we compared the extension and 90° flexion gap after every 5 MNPs in each group using the Wilcoxon signed-rank test, and the differences in between the groups were also compared using the Mann–Whitney U-test. Finally, to identify predictors for overrelease, multivariate linear regression analysis was performed to determine the association between patient and surgical factors (age, height, weight, BMI, width of MCL, severity of OA, initial medial extension and 90° flexion gap before MNP and MNP performance with the knee position in extension or 90° flexion) and the number of MNPs required to over-release. In addition, to identify risk factors for early over-release, univariate comparisons between early overrelease and late over-release were performed. Next, multivariate logistic analysis was performed based on variables with a P value b 0.1 in the univariate analysis, and odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for the occurrence of early over-release. Statistical analyses were conducted using SPSS for Windows (Version 17.0; SPSS Inc, Chicago, IL, USA). Results Both the medial extension and 90° flexion gaps gradually increased after every five needle punctures in both groups. In the E group, the extension gap increased from 0.6 ± 0.5 to 3.5 ± 0.5 mm, and the flexion gap increased from 1.1 ± 0.7 to 4.3 ± 0.8 mm (Fig. 3A). In the F group, extension increased from 0.8 ± 0.6 to 3.0 ± 1.4 mm and flexion increased from 2.3 ± 1.2 to 5.5 ± 0.7 mm (Fig. 3B). In addition, all extension and flexion gaps in both groups increased significantly compared to those associated with the previous five needle punctures, excluding the flexion gap change between 15 and 20 punctures in the F group (Fig. 3). When puncturing was done with the knee in flexion, the flexion gap increased more selectively than the extension gap. In contrast, when performed in extension, the extension gap did not increase more than the flexion gap. During 15 needle punctures, the 90° flexion gap increased more than did the extension gaps in the F group, but
there were no differences between extension and flexion in the E group (Table 2). In addition, the flexion gap in the F group was larger than that in the E group, but no group difference in the extension gap was found (Table 3). Knee position (extension or 90° flexion) during the needle puncture, width of MCL and severity of OA were identified as predictors for the number of MNPs required for over-release. In addition, the needle puncturing in a flexed knee and a narrow MCL were identified as risk factors for early over-release. The average number of MNPs required for over-release was 23 (range, 10–30) in both groups, but that in the F group (19 ± 5 punctures; range, 10– 25) was less than that in the E group (27 ± 4 punctures; range, 20– 30) (P = 0.001). In addition, more knees in the F group overreleased earlier than in the E group (P = 0.031) (Fig. 4). Linear regression analysis demonstrated that needle puncturing in a flexed knee, a narrow MCL, and severe OA were significantly associated with a lower number of needle punctures required for over-release (Table 4). The R 2 value for the multivariate regression model using these three variables was 0.708, indicating that 71% of the variation in the outcome could be explained by these three variables. Meanwhile, univariate comparisons revealed that needle puncturing in a flexed knee (70% vs. 30% in the F group, P = 0.031) and a narrow MCL (14 vs. 17 mm) differed between the early and late over-release groups. Multivariate logistic regression analysis revealed that needle puncturing in a flexed knee (OR, 70.9; 95% CI, 1.382–3632.101; P = 0.034) and narrow MCL (OR, 0.542; 95% CI, 0.306–0.960; P = 0.036) were risk factors for early over-release
Table 3 Comparison of the Extension and 90° Flexion Gaps Between the E and F Groups.a Medial Gap Increase (mm) Extension Gap
90° Flexion Gap
Number of MNPs
Group E
Group F
Significance
Group E
Group F
Significance
5 10 15 20
0.6 1.3 1.9 2.4
0.8 1.6 2.3 3.0
0.449 0.285 0.104 0.644
1.1 1.8 2.6 3.0
2.3 3.1 3.8 5.5
0.013 0.014 0.034 0.068
MNP, multiple needle puncture. a Data are presented as means.
Fig. 4. The proportion of over-released knees according to the number of needle punctures. More knees in the F group over-released earlier than in the E group. Values with a significant difference (P b 0.05) are marked with an asterisk.
Please cite this article as: Koh IJ, et al, How Effective Is Multiple Needle Puncturing for Medial Soft Tissue Balancing During Total Knee Arthroplasty? A Cadaveric Study, J Arthroplasty (2013), http://dx.doi.org/10.1016/j.arth.2013.11.004
I.J. Koh et al. / The Journal of Arthroplasty xxx (2013) xxx–xxx Table 4 Multivariate Regression Analysis for Identifying the Factors Associated With the Number of MNPs Required for Over-Release. Risk Factors Knee position during MNP MCL width Degree of OAb
B a
−8.930 0.614 −2.227
95% CI
R2
−12.193 to −5.666 0.100–1.127 −4.108 to −0.345
0.708
Significance b0.001 0.022 0.023
A negative B value means that severe OA was associated with fewer MNPs required for over-release. MNP, multiple needle puncture; MCL, medial collateral ligament; OA, osteoarthritis; CI, confidence interval. a MNP in extension was coded as 0 and that in 90° flexion was coded as 1; thus, a negative B value means that MNP in flexion was associated with fewer MNPs required for over-release. b Degree of OA was categorized into three groups: 0 = mild, 1 = moderate, and 2 = severe OA.
(Table 5). The R 2 value for this multivariate regression model using these two variables was 0.639.
Discussion Medial soft tissue balancing with the traditional subperiosteal release of the superficial MCL is technically demanding and often leads to over-release [2,6,24]. Recent clinical studies have proposed that needle puncturing in the MCL is an effective and safe technique for progressive correction of medial soft tissue balancing in moderate varus TKA [22,23]. However, information regarding quantitative changes in gap with increased numbers of needle punctures and the risk factors for over-release remain unclear. In this cadaveric study, we determined how much the medial extension and 90° flexion gaps increased after MNP; whether the extension and flexion gaps selectively increased depending on the position of the knee during needle puncture; and identified the risk factors for over-release for medial soft tissue balancing during TKA. Our study suggests that surgeons can control the increase in the medial joint gap in a gradual manner using MNP. Our results showed that the extension gap (within 4 mm; range, 0.6 ± 0.5 to 3.5 ± 0.5 mm) and the 90° flexion gap (within 6 mm; range, 1.1 ± 0.7 to 5.5 ± 0.7 mm) gradually increased after every five needle punctures. Our findings concur with recent clinical studies that reported that progressive and controlled medial soft tissue balancing was possible with MNP [22,23]; however, it is difficult to compare the degree of gap increase between the present and these previous studies, because the latter presented only quantitative information on the final remaining mediolateral laxity. Meanwhile, the authors in those of previous studies excluded patients with severe varus deformity exceeding 20°– 25° due to fears of increased medial soft tissue fibrosis. Taken together with those of previous studies, our results indicate that MNP is indicated in moderate varus deformity requiring a b4-mm increase in the extension gap and b6-mm increase in the flexion gap. Our findings partly support the hypothesis that a selective increase in the extension or 90° flexion gap is obtained by MNP. The flexion gap increased to a greater degree than did the extension gap with the knee in flexion during MNP, but no differences were noted when MNP was performed in the extended knee. In addition, the increased flexion gap Table 5 Multivariate Logistic Regression Analysis for Identifying Risk Factors for Early OverRelease (b25 MNPs). Risk Factors
Exp (B)
Significance
Knee position during MNPa MCL width
70.855 0.542
0.034 0.036
95% CI 1.382–3632.101 0.306–0.960
MNP, multiple needle puncture; MCL, medial collateral ligament; CI, confidence interval. a MNP in extension was coded as 0, and that in 90° flexion was coded as 1.
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with the knee in flexion was larger than that with the knee in extension, but no differences in the extension gap were found. This partial selectivity may be the result of the lack of supporting structures in the anteromedial portion of the knee compared to the posteromedial portion. Typically, when the knee is flexed, the anterior portion of the MCL becomes more tense, and the tensest fibers for needle puncture are palpated anteriorly; however, when the knee is extended, the tensest fibers are usually palpated at the posterior portion [18,22,25,26]. After medial parapatellar arthrotomy, only the anterior portion of the MCL retains its anteromedial soft tissue structure, whereas the posteromedial portion is also supported by the posteromedial joint capsule, tendinous portion of the semimembranous, and posterior oblique ligament that is located posterior to superficial MCL and consists of three fascial layer which ran from proximal and posterior to femoral attachment site of superficial MCL to distal tibial expansion of the semimembranous and posteromedial joint capsule [25–28]. Therefore, MNP in the anterior fibers of the MCL may more potently affect the 90° flexion gap increase, whereas MNP in the posterior fibers of the MCL may not selectively increase the extension gap. Our findings suggest that additional posteromedial soft tissue release is required to further increase the extension gap during MNP in extension. Our results also indicate that the flexed or extended knee position during needle puncture, the width of the MCL, and the severity of OA are predictors of the number of MNPs required for over-release. Linear regression analysis revealed that MNP in the flexed knee, a narrow MCL, and severe OA were associated with fewer MNPs required for over-release. In addition, logistic regression analysis identified MNP in the flexed knee and a narrow MCL as risk factors for early overrelease. The number of MNPs required for over-release in the flexed knee was less than that required for the knee in extension (19 ± 5 punctures; range, 10–25 in the F group vs. 27 ± 4 punctures; range, 20–30 in the E group, P = 0.001); in addition, more knees in flexion over-released earlier than in extension. This early over-release in the flexed knee may be due to the lack of anteromedial supporting structures other than the MCL. Our results also indicate that overrelease is affected by the anteroposterior length of the MCL rather than the proximodistal length (the initial joint gap before MNP). Because the needle pierces the tensest longitudinal fiber in the MCL during MNP, the room for MNP is reduced in a narrow MCL and the risk of over-release increases. Finally, pathologic fibrosis and severe contracture of the medial soft tissue structures are typically present in advanced varus knee OA, which often required more than 5 mm of medial gap release in our clinical practice. These findings together with our results demonstrating the maximal amount of increased medial gap following MNP as approximately 5 mm, suggest that the risk of transection or mechanical failure of the MCL increases during MNP in knees with severe varus knee OA, therefore, a traditional subperiosteal release of MCL might offer more efficient medial gap release in knees with severe varus deformity. Our findings suggest that surgeons should reduce the interval of re-assessment of the gap increase when MNP is performed in a flexed knee in patients with severe OA and a narrow MCL. Several limitations of this study should be noted. First, 50% of our cadaveric specimens did not demonstrate change in OA. Because the amount of gap increase after MNP may differ in severely arthritic knees, this factor should be considered before extrapolating our findings to other populations. Second, we did not assess preoperative radiographic varus deformity. Because varus deformity is associated with the arthritic process, which results in fibrosis of medial soft tissue, it can be another predictor for early over-release after MNP in addition to the factors assessed in this study. Third, the positions of the tensor device and the knee during the measurement may have affected the assessment of the joint gap. We made every effort to consistently place the tensor device and to push it as deeply as possible into the joint to prevent the top plates from bending.
Please cite this article as: Koh IJ, et al, How Effective Is Multiple Needle Puncturing for Medial Soft Tissue Balancing During Total Knee Arthroplasty? A Cadaveric Study, J Arthroplasty (2013), http://dx.doi.org/10.1016/j.arth.2013.11.004
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I.J. Koh et al. / The Journal of Arthroplasty xxx (2013) xxx–xxx
Nonetheless, we believe that the use of the tensor device during MNP is beneficial in that it enables easy palpation of the tensest fibers in the MCL and accurate performance of the needle puncture. Fourth, we applied a 200-N force to distract the joint during all measurements. How much distraction force is optimal remains unclear. Previous studies have used a wide variety of distraction forces, ranging from 80 to 200 N [1,8,9,29]. The distraction force used may affect the gap increase, and thus the force used in this study should be considered before extrapolating our quantitative gap information. Finally, we did not take into account the changes in the lateral joint gap after needle puncture in the MCL, but the information on the lateral joint gap was clinically needed to create equal extension and the 90° flexion gaps during TKA. However, to the best of our knowledge, this is the first cadaveric study to report the quantitative effect of MNP on the medial joint gap. Further studies that evaluate the effect of MNP on both the medial and lateral joint gaps are needed. Despite these limitations, this study provides valuable information on the gap increase after MNP which reflected the real condition of gap balancing during TKA using currently available gap assessment devices in practice. Our study demonstrated that MNP can offer a gradual increase in the medial joint gap (less than 4 mm in the extension gap and less than 6 mm in the flexion gap). In addition, the 90° flexion gap is more selectively increased than is the extension gap. However, even with MNP, over-release can occur and the surgeon should be aware of the possibility of over-release when the MCL is narrow and MNP is performed with the knee in flexion. References 1. Luring C, Hufner T, Perlick L, et al. The effectiveness of sequential medial soft tissue release on coronal alignment in total knee arthroplasty: using a computer navigation model. J Arthroplasty 2006;21:428. 2. Matsumoto T, Kuroda R, Kubo S, et al. The intra-operative joint gap in cruciateretaining compared with posterior-stabilised total knee replacement. J Bone Joint Surg Br 2009;91:475. 3. Winemaker MJ. Perfect balance in total knee arthroplasty: the elusive compromise. J Arthroplasty 2002;17:2. 4. Yagishita K, Muneta T, Ikeda H. Step-by-step measurements of soft tissue balancing during total knee arthroplasty for patients with varus knees. J Arthroplasty 2003;18(3):313. 5. Dorr LD, Boiardo RA. Technical considerations in total knee arthroplasty. Clin Orthop Relat Res 1986;205:5. 6. D'Lima DD, Patil S, Steklov N, et al. Best paper: dynamic intraoperative ligament balancing for total knee arthroplasty. Clin Orthop Relat Res 2007;463:208. 7. Insall JN, Binazzi R, Soudry M, et al. Total knee arthroplasty. Clin Orthop Relat Res 1985;192:13.
8. Heesterbeek PJ, Jacobs WC, Wymenga AB. Effects of the balanced gap technique on femoral component rotation in TKA. Clin Orthop Relat Res 2009;467:1015. 9. Nowakowski AM, Majewski M, Muller-Gerbl M, et al. Development of a forcedetermining tensor to measure “physiologic knee ligament gaps” without bone resection using a total knee arthroplasty approach. J Orthop Sci 2011;16:56. 10. Chang CB, Choi JY, Koh IJ, et al. What should be considered in using standard knee radiographs to estimate mechanical alignment of the knee? Osteoarthritis Cartilage 2010;18:530. 11. Chang CB, Koh IJ, Seo ES, et al. The radiographic predictors of symptom severity in advanced knee osteoarthritis with varus deformity. Knee 2011;18:456. 12. Lasam MP, Lee KJ, Chang CB, et al. Femoral lateral bowing and varus condylar orientation are prevalent and affect axial alignment of TKA in Koreans. Clin Orthop Relat Res 2013;471:1472. 13. Luring C, Bathis H, Hufner T, et al. Gap configuration and anteroposterior leg axis after sequential medial ligament release in rotating-platform total knee arthroplasty. Acta Orthop 2006;77:149. 14. Matsueda M, Gengerke TR, Murphy M, et al. Soft tissue release in total knee arthroplasty. Cadaver study using knees without deformities. Clin Orthop Relat Res 1999;366:264. 15. Laskin RS. The Insall Award. Total knee replacement with posterior cruciate ligament retention in patients with a fixed varus deformity. Clin Orthop Relat Res 1996;331:29. 16. Lombardi Jr AV, Nett MP, Scott WN, et al. Primary total knee arthroplasty. J Bone Joint Surg Am 2009;91(Suppl 5):52. 17. Teeny SM, Krackow KA, Hungerford DS, et al. Primary total knee arthroplasty in patients with severe varus deformity. A comparative study. Clin Orthop Relat Res 1991;273:19. 18. Whiteside LA, Saeki K, Mihalko WM. Functional medical ligament balancing in total knee arthroplasty. Clin Orthop Relat Res 2000;380:45. 19. Tanaka K, Muratsu H, Mizuno K, et al. Soft tissue balance measurement in anterior cruciate ligament-resected knee joint: cadaveric study as a model for cruciateretaining total knee arthroplasty. J Orthop Sci 2007;12:149. 20. Aglietti P, Lup D, Cuomo P, et al. Total knee arthroplasty using a pie-crusting technique for valgus deformity. Clin Orthop Relat Res 2007;464:73. 21. Clarke HD, Fuchs R, Scuderi GR, et al. Clinical results in valgus total knee arthroplasty with the “pie crust” technique of lateral soft tissue releases. J Arthroplasty 2005;20:1010. 22. Bellemans J. Multiple needle puncturing: balancing the varus knee. Orthopedics 2011;34:e510. 23. Bellemans J, Vandenneucker H, Van Lauwe J, et al. A new surgical technique for medial collateral ligament balancing: multiple needle puncturing. J Arthroplasty 2010;25:1151. 24. Koh HS, In Y. Semimembranosus release as the second step of soft tissue balancing in varus total knee arthroplasty. J Arthroplasty 2013;28:273. 25. Warren LA, Marshall JL, Girgis F. The prime static stabilizer of the medical side of the knee. J Bone Joint Surg Am 1974;56:665. 26. Warren LF, Marshall JL. The supporting structures and layers on the medial side of the knee: an anatomical analysis. J Bone Joint Surg Am 1979;61:56. 27. LaPrade RF, Engebretsen AH, Ly TV, et al. The anatomy of the medial part of the knee. J Bone Joint Surg Am 2007;89:2000. 28. LaPrade RF, Morgan PM, Wentorf FA, et al. The anatomy of the posterior aspect of the knee. An anatomic study. J Bone Joint Surg Am 2007;89:758. 29. Asano H, Hoshino A, Wilton TJ. Soft-tissue tension total knee arthroplasty. J Arthroplasty 2004;19:558.
Please cite this article as: Koh IJ, et al, How Effective Is Multiple Needle Puncturing for Medial Soft Tissue Balancing During Total Knee Arthroplasty? A Cadaveric Study, J Arthroplasty (2013), http://dx.doi.org/10.1016/j.arth.2013.11.004
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How Effective Is Multiple Needle Puncturing for Medial Soft Tissue Balancing During Total Knee Arthroplasty? A Cadaveric Study In Jun Koh, MD a, b, Dai-Soon Kwak, PhD c, Tae Kyun Kim, MD, PhD d, In Joo Park, MD a, b, Yong In, MD, PhD b, e a
Department of Orthopaedic Surgery, Uijeongbu St. Mary’s Hospital, Uijeongbu-si, Gyeonggi-do, Korea Department of Orthopaedic Surgery, The Catholic University of Korea College of Medicine, Seoul, Korea Catholic Institute for Applied Anatomy, The Catholic University of Korea College of Medicine, Seoul, Korea d Joint Reconstruction Center, Seoul National University Bundang Hospital, Seongnam-si, Gyeonggi-do, Korea e Department of Orthopaedic Surgery, Seoul St. Mary’s Hospital, Seoul, Korea b c
a r t i c l e
i n f o
Article history: Received 20 August 2013 Accepted 3 November 2013 Available online xxxx Keywords: multiple needle puncturing medial collateral ligament gap balancing varus total knee arthroplasty
a b s t r a c t We investigated the quantitative effect and risk factors for over-release during multiple needle puncturing (MNP) for medial gap balancing in varus total knee arthroplasty (TKA). Of the ten pairs of cadaveric knees, one knee from each pair was randomly assigned to undergo MNP in extension (E group), while the other knee underwent MNP in flexion (F group). The increased extension and 90° flexion gaps after every five needle punctures were measured until over-release occurred. The extension gap (b 4 mm) and the 90° flexion gap (b 6 mm) gradually increased in both groups. The 90° flexion gaps increased more selectively than did the extension gaps. MNP in the flexed knee, a narrow MCL, and severe osteoarthritis were associated with a smaller number of MNPs required to over-release. © 2013 Elsevier Inc. All rights reserved.
Restoration of proper limb alignment and achievement of adequate soft tissue balance are essential for successful total knee arthroplasty (TKA) [1–5]. In addition, inadequate soft tissue balancing after TKA can lead to early failure such as instability, wear and loosening [6,7]. Given the paramount importance of gap measurement, various techniques and instruments for gap balancing such as laminar spreader, spacer block, and trial component have been suggested. In addition, recently developed instrumented tensioners permit surgeons to assess gap balance with a constant joint distraction force [2,8,9], but no standard gap assessment technique has been established. Meanwhile, because most TKA candidates typically present with preoperative varus knee deformity [10–12], medial tightness which requires further medial soft tissue release for accurate balancing is commonly encountered despite adequate bone resection and preliminary soft tissue release. Traditionally, a gradual subperiosteal release of the superficial medial collateral ligament (MCL) has been carried out in this clinical scenario [1,13–18]. However, because precise gap balancing when using this method is technically demanding [6,19], the correction of moderate varus deformity, which requires a modest increase in the medial joint gap, remains challenging. In addition, it often leads to over-release of the The Conflict of Interest statement associated with this article can be found at http:// dx.doi.org/10.1016/j.arth.2013.11.004. ⁎ Reprint requests: Yong In, MD, PhD, Department of Orthopaedic Surgery, Seoul St. Mary’s Hospital, 222 Banpo-daero, Seocho-gu, Seoul (137-701), Korea.
superficial MCL, resulting in catastrophic instability. Therefore, medial soft tissue balancing with this method is usually dependent upon the surgeon’s experience. Recently, multiple needle puncturing (MNP) in the MCL, a version of the pie-crusting technique which comes from lateral soft tissue release in patients with valgus deformity [16,20,21], was reported to be an effective and safe technique for progressive correction of moderate varus deformity during TKA [22,23]. In those of previous studies, needle punctures were progressively increased until 2 to 4 mm of mediolateral joint laxity in extension or 2 to 6 mm at 90° flexion was obtained, and the mediolateral balance was assessed using maximal manual varus–valgus stress. In addition, MNP has been performed with the knee either in extension or in flexion depending on when tightness was observed. However, quantitative gap information after MNP has not been presented, only the final obtained mediolateral joint laxity. Therefore, there is lack of quantitative data on how each needle puncture increases the medial joint gap with application of a constant distraction force for joint opening and whether the extended or flexed knee position during MNP affects the increase in the extension and 90° flexion gaps. In addition, although over-release reportedly occurs in 5% of patients [22], the number of needle punctures required for over-release and the risk factors for over-release during MNP remain unclear. We therefore sought to determine the quantitative effects of MNP on medial extension and 90° flexion gaps, whether the amount of increase in extension and 90° flexion gaps differs depending on
0883-5403/0000-0000$36.00/0 – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.arth.2013.11.004
Please cite this article as: Koh IJ, et al, How Effective Is Multiple Needle Puncturing for Medial Soft Tissue Balancing During Total Knee Arthroplasty? A Cadaveric Study, J Arthroplasty (2013), http://dx.doi.org/10.1016/j.arth.2013.11.004
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I.J. Koh et al. / The Journal of Arthroplasty xxx (2013) xxx–xxx
whether the knee is in extension or flexion during MNP, and to identify the risk factors for over-release using MNP for medial soft tissue balancing during TKA. We hypothesized that both extension and 90° flexion gap would gradually increase after MNP and would selectively increase after MNP. We also hypothesized that several factors would predict fewer MNPs leading to over-release. Materials and Methods We used 10 pairs of knees in this study (20 fresh-frozen cadaveric knees; 10 female, 10 male; mean ± standard deviation age, 75 ± 9 years; height, 158 ± 8 cm; weight, 53 ± 14 kg). As the taut portion of MCL moves anteriorly with the knee in flexion and posteriorly in extension, for each cadaver, we randomly assigned one knee to the extension (E) group, in which needle punctures were performed with the knee in extension, and the other knee to the flexion (F) group, in which the punctures were carried out with the knee in 90° flexion. Knees with previous lower extremity surgery (including hip and ankle) or trauma, as evidenced by visual scar or deformities were excluded. We performed an a priori power analysis to determine the appropriate number of specimens required to detect a difference in the amount of increase in the medial joint gap after each of five needle punctures. Ten pairs of specimens were required to detect a 1-mm increase in gap at an alpha level of 0.05 and with a power of 80% using a two-sided test. All surgical procedures were performed by a single surgeon (one of the authors) using a standard posterior-stabilized prosthesis instrumentation system (Genesis II; Smith & Nephew, Memphis, TN, USA). After performing a standard midline skin incision and medial parapatellar arthrotomy, the patella was subluxed. Then, the anterior cruciate ligament and both menisci were excised. Resection of the distal femur was carried out using intramedullary instrumentation with a 6° valgus angle, and the posterior cruciate ligament was thoroughly removed from the femoral attachment site after anterior– posterior femoral resection. Next, proximal tibia resection was performed using extramedullary instrumentation to resect a 10-mm in thickness from the lateral plateau with a cutting angle of 90° to the tibial axis. Measurement of the medial extension and 90° flexion gaps was performed using a tensor device (B Braun-Aesculap, Tuttlingen, Germany) and scaled-force forceps (B Braun-Aesculap) (Fig. 1). The tensor device has a base plate that is placed onto the resected tibial surface and two independent top plates that are placed onto each of
Fig. 1. Photograph showing how the joint gaps were measured. After standard bone resection, the extension and 90° flexion gaps were measured using a tensor device with the application of a 200-N distraction force via the scaled forceps.
the medial and lateral resected femoral undersurfaces. In addition, it can be distracted and maintained separately and has two independent scales connected to each plate indicating the distance from the base plate to the top plate. The forceps include a scale (range, 50–250 N) that indicates the amount of force applied to the tensor device. The tip of the base plate and each of the top plates were placed perpendicular to both the resected tibial and femoral surfaces, and the tensor device was pushed into the joint as deeply as possible to prevent the top plates from bending. During measurement of the extension gap, the thigh and leg were supported by assistants to maintain full extension, and 90° flexion of the knee was maintained during the 90° flexion gap measurement. During every measurement, a 200-N force, as indicated by the forceps scale, was applied to both the medial and lateral top plates by an investigator (one of the authors), and the measurement in millimeters as read from the scale of the tensor device was recorded. MNP was performed in the medial soft tissue of the joint which was distracted by the tensor device with a 200-N distraction force (Fig. 2). A single surgeon (one of the authors) made the needle punctures with a standard 18-gauge aspiration needle at the tensest fibers as determined by digital palpation. The punctures were made every 3 to 5 mm in the proximodistal and anteroposterior directions, as described in previous studies [22,23]. The joint gap increase was reassessed after every five needle punctures using the tensor device with a 200-N distraction force. In the E group, the needle punctures were performed with the knee in extension (Fig. 2A), and in the F group, they were performed with the knee in 90° flexion (Fig. 2B). The needle puncturing was continued until “over-release” occurred in the medial soft tissue. Over-release was defined as the point at which the structural integrity of the medial soft tissue was disrupted and the end-point of the medial joint gap was not detectable despite application of a 250-N distraction force, due to loss of mechanical strength. In addition, we classified knees
Fig. 2. Photograph showing how needle puncturing was done in the extended knee (A) and the flexed knee (B). Maintaining joint distraction with a tensor device, the tensest fibers were identified by digital palpation and punctured with a standard 18-gauge aspiration needle.
Please cite this article as: Koh IJ, et al, How Effective Is Multiple Needle Puncturing for Medial Soft Tissue Balancing During Total Knee Arthroplasty? A Cadaveric Study, J Arthroplasty (2013), http://dx.doi.org/10.1016/j.arth.2013.11.004
I.J. Koh et al. / The Journal of Arthroplasty xxx (2013) xxx–xxx Table 1 Comparison of the Severity of OA and MCL Width in Each Group. Group E OA severitya Mild Moderate Severe MCL width (mm)b
Group F
Significance 1.000
50 20 30 15.3 (3.4)
50 20 30 16.0 (3.4)
0.648
OA, osteoarthritis; MCL, medial collateral ligament. a Data are presented as percentages; the severity of OA was graded as mild, moderate, or severe. b Data are presented as mean (SD).
into early (late) over-release groups when it occurred earlier (later) than the average number of MNPs required for over-release in this study.
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Information including the age, gender, weight, and height of each cadaveric specimen was collected by an investigator (one of the authors). The severity of osteoarthritis (OA) in each cadaveric specimen was graded as mild (no articular cartilaginous lesion), moderate (focal lesion), or severe (extensive lesion) after the arthrotomy. In addition, the width of the MCL was measured using calipers at the level of the joint line after bone resection with the knee in extension in the E group, and with the knee in flexion in the F group (Table 1). The primary outcome variable was the medial extension and the 90° flexion gap increase after every five needle punctures in both groups, and the secondary outcome variables were the number of MNPs leading to over-release and predictors for over-release. To determine the effectiveness of MNP on the medial joint gap, we compared each change in the medial extension and 90° flexion gaps
Fig. 3. The degree of each extension and 90° flexion gap increased significantly after every five needle punctures in the E group (A) and in the F group (B), with the exception of those between 15 and 20 needle punctures in the F group. Values with a significant difference (P b 0.05) are marked with an asterisk.
Please cite this article as: Koh IJ, et al, How Effective Is Multiple Needle Puncturing for Medial Soft Tissue Balancing During Total Knee Arthroplasty? A Cadaveric Study, J Arthroplasty (2013), http://dx.doi.org/10.1016/j.arth.2013.11.004
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I.J. Koh et al. / The Journal of Arthroplasty xxx (2013) xxx–xxx
Table 2 Comparison of the Gap Increase Between the Extension and 90° Flexion Gaps in Each Group.a Medial Gap Increase (mm) Group E Extension Gap
Number of MNPs
Mean
5 10 15 20 25
0.6 (0.5) 1.3 (0.5) 1.9 (0.3) 2.4 (0.5) 3.5 (0.5)
Range 0–1 1–2 1–2 2–3 3–4
Group F
90° Flexion Gap Mean 1.1 1.8 2.6 3.0 4.3
(0.7) (1.0) (1.4) (0.8) (0.8)
Extension Gap
Range
Significance
0–2 1–4 1–5 2–4 3–5
0.138 0.177 0.111 0.140 0.093
Mean 0.8 (0.6) 1.6 (0.5) 2.3 (0.5) 3.0 (1.4) N/A
Range 0–2 1–2 2–3 2–4
90° Flexion Gap Mean 2.3 3.1 3.8 5.5
(1.2) (1.1) (0.8) (0.7)
Range
Significance
1–4 2–5 3–5 5–6
0.009 0.008 0.007 0.126
MNP, multiple needle puncture. a Data are presented as mean (SD).
after every 5 needle punctures using the Wilcoxon signed-rank test. In addition, to determine whether the extension and 90° flexion gap increased selectively, we compared the extension and 90° flexion gap after every 5 MNPs in each group using the Wilcoxon signed-rank test, and the differences in between the groups were also compared using the Mann–Whitney U-test. Finally, to identify predictors for overrelease, multivariate linear regression analysis was performed to determine the association between patient and surgical factors (age, height, weight, BMI, width of MCL, severity of OA, initial medial extension and 90° flexion gap before MNP and MNP performance with the knee position in extension or 90° flexion) and the number of MNPs required to over-release. In addition, to identify risk factors for early over-release, univariate comparisons between early overrelease and late over-release were performed. Next, multivariate logistic analysis was performed based on variables with a P value b 0.1 in the univariate analysis, and odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for the occurrence of early over-release. Statistical analyses were conducted using SPSS for Windows (Version 17.0; SPSS Inc, Chicago, IL, USA). Results Both the medial extension and 90° flexion gaps gradually increased after every five needle punctures in both groups. In the E group, the extension gap increased from 0.6 ± 0.5 to 3.5 ± 0.5 mm, and the flexion gap increased from 1.1 ± 0.7 to 4.3 ± 0.8 mm (Fig. 3A). In the F group, extension increased from 0.8 ± 0.6 to 3.0 ± 1.4 mm and flexion increased from 2.3 ± 1.2 to 5.5 ± 0.7 mm (Fig. 3B). In addition, all extension and flexion gaps in both groups increased significantly compared to those associated with the previous five needle punctures, excluding the flexion gap change between 15 and 20 punctures in the F group (Fig. 3). When puncturing was done with the knee in flexion, the flexion gap increased more selectively than the extension gap. In contrast, when performed in extension, the extension gap did not increase more than the flexion gap. During 15 needle punctures, the 90° flexion gap increased more than did the extension gaps in the F group, but
there were no differences between extension and flexion in the E group (Table 2). In addition, the flexion gap in the F group was larger than that in the E group, but no group difference in the extension gap was found (Table 3). Knee position (extension or 90° flexion) during the needle puncture, width of MCL and severity of OA were identified as predictors for the number of MNPs required for over-release. In addition, the needle puncturing in a flexed knee and a narrow MCL were identified as risk factors for early over-release. The average number of MNPs required for over-release was 23 (range, 10–30) in both groups, but that in the F group (19 ± 5 punctures; range, 10– 25) was less than that in the E group (27 ± 4 punctures; range, 20– 30) (P = 0.001). In addition, more knees in the F group overreleased earlier than in the E group (P = 0.031) (Fig. 4). Linear regression analysis demonstrated that needle puncturing in a flexed knee, a narrow MCL, and severe OA were significantly associated with a lower number of needle punctures required for over-release (Table 4). The R 2 value for the multivariate regression model using these three variables was 0.708, indicating that 71% of the variation in the outcome could be explained by these three variables. Meanwhile, univariate comparisons revealed that needle puncturing in a flexed knee (70% vs. 30% in the F group, P = 0.031) and a narrow MCL (14 vs. 17 mm) differed between the early and late over-release groups. Multivariate logistic regression analysis revealed that needle puncturing in a flexed knee (OR, 70.9; 95% CI, 1.382–3632.101; P = 0.034) and narrow MCL (OR, 0.542; 95% CI, 0.306–0.960; P = 0.036) were risk factors for early over-release
Table 3 Comparison of the Extension and 90° Flexion Gaps Between the E and F Groups.a Medial Gap Increase (mm) Extension Gap
90° Flexion Gap
Number of MNPs
Group E
Group F
Significance
Group E
Group F
Significance
5 10 15 20
0.6 1.3 1.9 2.4
0.8 1.6 2.3 3.0
0.449 0.285 0.104 0.644
1.1 1.8 2.6 3.0
2.3 3.1 3.8 5.5
0.013 0.014 0.034 0.068
MNP, multiple needle puncture. a Data are presented as means.
Fig. 4. The proportion of over-released knees according to the number of needle punctures. More knees in the F group over-released earlier than in the E group. Values with a significant difference (P b 0.05) are marked with an asterisk.
Please cite this article as: Koh IJ, et al, How Effective Is Multiple Needle Puncturing for Medial Soft Tissue Balancing During Total Knee Arthroplasty? A Cadaveric Study, J Arthroplasty (2013), http://dx.doi.org/10.1016/j.arth.2013.11.004
I.J. Koh et al. / The Journal of Arthroplasty xxx (2013) xxx–xxx Table 4 Multivariate Regression Analysis for Identifying the Factors Associated With the Number of MNPs Required for Over-Release. Risk Factors Knee position during MNP MCL width Degree of OAb
B a
−8.930 0.614 −2.227
95% CI
R2
−12.193 to −5.666 0.100–1.127 −4.108 to −0.345
0.708
Significance b0.001 0.022 0.023
A negative B value means that severe OA was associated with fewer MNPs required for over-release. MNP, multiple needle puncture; MCL, medial collateral ligament; OA, osteoarthritis; CI, confidence interval. a MNP in extension was coded as 0 and that in 90° flexion was coded as 1; thus, a negative B value means that MNP in flexion was associated with fewer MNPs required for over-release. b Degree of OA was categorized into three groups: 0 = mild, 1 = moderate, and 2 = severe OA.
(Table 5). The R 2 value for this multivariate regression model using these two variables was 0.639.
Discussion Medial soft tissue balancing with the traditional subperiosteal release of the superficial MCL is technically demanding and often leads to over-release [2,6,24]. Recent clinical studies have proposed that needle puncturing in the MCL is an effective and safe technique for progressive correction of medial soft tissue balancing in moderate varus TKA [22,23]. However, information regarding quantitative changes in gap with increased numbers of needle punctures and the risk factors for over-release remain unclear. In this cadaveric study, we determined how much the medial extension and 90° flexion gaps increased after MNP; whether the extension and flexion gaps selectively increased depending on the position of the knee during needle puncture; and identified the risk factors for over-release for medial soft tissue balancing during TKA. Our study suggests that surgeons can control the increase in the medial joint gap in a gradual manner using MNP. Our results showed that the extension gap (within 4 mm; range, 0.6 ± 0.5 to 3.5 ± 0.5 mm) and the 90° flexion gap (within 6 mm; range, 1.1 ± 0.7 to 5.5 ± 0.7 mm) gradually increased after every five needle punctures. Our findings concur with recent clinical studies that reported that progressive and controlled medial soft tissue balancing was possible with MNP [22,23]; however, it is difficult to compare the degree of gap increase between the present and these previous studies, because the latter presented only quantitative information on the final remaining mediolateral laxity. Meanwhile, the authors in those of previous studies excluded patients with severe varus deformity exceeding 20°– 25° due to fears of increased medial soft tissue fibrosis. Taken together with those of previous studies, our results indicate that MNP is indicated in moderate varus deformity requiring a b4-mm increase in the extension gap and b6-mm increase in the flexion gap. Our findings partly support the hypothesis that a selective increase in the extension or 90° flexion gap is obtained by MNP. The flexion gap increased to a greater degree than did the extension gap with the knee in flexion during MNP, but no differences were noted when MNP was performed in the extended knee. In addition, the increased flexion gap Table 5 Multivariate Logistic Regression Analysis for Identifying Risk Factors for Early OverRelease (b25 MNPs). Risk Factors
Exp (B)
Significance
Knee position during MNPa MCL width
70.855 0.542
0.034 0.036
95% CI 1.382–3632.101 0.306–0.960
MNP, multiple needle puncture; MCL, medial collateral ligament; CI, confidence interval. a MNP in extension was coded as 0, and that in 90° flexion was coded as 1.
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with the knee in flexion was larger than that with the knee in extension, but no differences in the extension gap were found. This partial selectivity may be the result of the lack of supporting structures in the anteromedial portion of the knee compared to the posteromedial portion. Typically, when the knee is flexed, the anterior portion of the MCL becomes more tense, and the tensest fibers for needle puncture are palpated anteriorly; however, when the knee is extended, the tensest fibers are usually palpated at the posterior portion [18,22,25,26]. After medial parapatellar arthrotomy, only the anterior portion of the MCL retains its anteromedial soft tissue structure, whereas the posteromedial portion is also supported by the posteromedial joint capsule, tendinous portion of the semimembranous, and posterior oblique ligament that is located posterior to superficial MCL and consists of three fascial layer which ran from proximal and posterior to femoral attachment site of superficial MCL to distal tibial expansion of the semimembranous and posteromedial joint capsule [25–28]. Therefore, MNP in the anterior fibers of the MCL may more potently affect the 90° flexion gap increase, whereas MNP in the posterior fibers of the MCL may not selectively increase the extension gap. Our findings suggest that additional posteromedial soft tissue release is required to further increase the extension gap during MNP in extension. Our results also indicate that the flexed or extended knee position during needle puncture, the width of the MCL, and the severity of OA are predictors of the number of MNPs required for over-release. Linear regression analysis revealed that MNP in the flexed knee, a narrow MCL, and severe OA were associated with fewer MNPs required for over-release. In addition, logistic regression analysis identified MNP in the flexed knee and a narrow MCL as risk factors for early overrelease. The number of MNPs required for over-release in the flexed knee was less than that required for the knee in extension (19 ± 5 punctures; range, 10–25 in the F group vs. 27 ± 4 punctures; range, 20–30 in the E group, P = 0.001); in addition, more knees in flexion over-released earlier than in extension. This early over-release in the flexed knee may be due to the lack of anteromedial supporting structures other than the MCL. Our results also indicate that overrelease is affected by the anteroposterior length of the MCL rather than the proximodistal length (the initial joint gap before MNP). Because the needle pierces the tensest longitudinal fiber in the MCL during MNP, the room for MNP is reduced in a narrow MCL and the risk of over-release increases. Finally, pathologic fibrosis and severe contracture of the medial soft tissue structures are typically present in advanced varus knee OA, which often required more than 5 mm of medial gap release in our clinical practice. These findings together with our results demonstrating the maximal amount of increased medial gap following MNP as approximately 5 mm, suggest that the risk of transection or mechanical failure of the MCL increases during MNP in knees with severe varus knee OA, therefore, a traditional subperiosteal release of MCL might offer more efficient medial gap release in knees with severe varus deformity. Our findings suggest that surgeons should reduce the interval of re-assessment of the gap increase when MNP is performed in a flexed knee in patients with severe OA and a narrow MCL. Several limitations of this study should be noted. First, 50% of our cadaveric specimens did not demonstrate change in OA. Because the amount of gap increase after MNP may differ in severely arthritic knees, this factor should be considered before extrapolating our findings to other populations. Second, we did not assess preoperative radiographic varus deformity. Because varus deformity is associated with the arthritic process, which results in fibrosis of medial soft tissue, it can be another predictor for early over-release after MNP in addition to the factors assessed in this study. Third, the positions of the tensor device and the knee during the measurement may have affected the assessment of the joint gap. We made every effort to consistently place the tensor device and to push it as deeply as possible into the joint to prevent the top plates from bending.
Please cite this article as: Koh IJ, et al, How Effective Is Multiple Needle Puncturing for Medial Soft Tissue Balancing During Total Knee Arthroplasty? A Cadaveric Study, J Arthroplasty (2013), http://dx.doi.org/10.1016/j.arth.2013.11.004
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Nonetheless, we believe that the use of the tensor device during MNP is beneficial in that it enables easy palpation of the tensest fibers in the MCL and accurate performance of the needle puncture. Fourth, we applied a 200-N force to distract the joint during all measurements. How much distraction force is optimal remains unclear. Previous studies have used a wide variety of distraction forces, ranging from 80 to 200 N [1,8,9,29]. The distraction force used may affect the gap increase, and thus the force used in this study should be considered before extrapolating our quantitative gap information. Finally, we did not take into account the changes in the lateral joint gap after needle puncture in the MCL, but the information on the lateral joint gap was clinically needed to create equal extension and the 90° flexion gaps during TKA. However, to the best of our knowledge, this is the first cadaveric study to report the quantitative effect of MNP on the medial joint gap. Further studies that evaluate the effect of MNP on both the medial and lateral joint gaps are needed. Despite these limitations, this study provides valuable information on the gap increase after MNP which reflected the real condition of gap balancing during TKA using currently available gap assessment devices in practice. Our study demonstrated that MNP can offer a gradual increase in the medial joint gap (less than 4 mm in the extension gap and less than 6 mm in the flexion gap). In addition, the 90° flexion gap is more selectively increased than is the extension gap. However, even with MNP, over-release can occur and the surgeon should be aware of the possibility of over-release when the MCL is narrow and MNP is performed with the knee in flexion. References 1. Luring C, Hufner T, Perlick L, et al. The effectiveness of sequential medial soft tissue release on coronal alignment in total knee arthroplasty: using a computer navigation model. J Arthroplasty 2006;21:428. 2. Matsumoto T, Kuroda R, Kubo S, et al. The intra-operative joint gap in cruciateretaining compared with posterior-stabilised total knee replacement. J Bone Joint Surg Br 2009;91:475. 3. Winemaker MJ. Perfect balance in total knee arthroplasty: the elusive compromise. J Arthroplasty 2002;17:2. 4. Yagishita K, Muneta T, Ikeda H. Step-by-step measurements of soft tissue balancing during total knee arthroplasty for patients with varus knees. J Arthroplasty 2003;18(3):313. 5. Dorr LD, Boiardo RA. Technical considerations in total knee arthroplasty. Clin Orthop Relat Res 1986;205:5. 6. D'Lima DD, Patil S, Steklov N, et al. Best paper: dynamic intraoperative ligament balancing for total knee arthroplasty. Clin Orthop Relat Res 2007;463:208. 7. Insall JN, Binazzi R, Soudry M, et al. Total knee arthroplasty. Clin Orthop Relat Res 1985;192:13.
8. Heesterbeek PJ, Jacobs WC, Wymenga AB. Effects of the balanced gap technique on femoral component rotation in TKA. Clin Orthop Relat Res 2009;467:1015. 9. Nowakowski AM, Majewski M, Muller-Gerbl M, et al. Development of a forcedetermining tensor to measure “physiologic knee ligament gaps” without bone resection using a total knee arthroplasty approach. J Orthop Sci 2011;16:56. 10. Chang CB, Choi JY, Koh IJ, et al. What should be considered in using standard knee radiographs to estimate mechanical alignment of the knee? Osteoarthritis Cartilage 2010;18:530. 11. Chang CB, Koh IJ, Seo ES, et al. The radiographic predictors of symptom severity in advanced knee osteoarthritis with varus deformity. Knee 2011;18:456. 12. Lasam MP, Lee KJ, Chang CB, et al. Femoral lateral bowing and varus condylar orientation are prevalent and affect axial alignment of TKA in Koreans. Clin Orthop Relat Res 2013;471:1472. 13. Luring C, Bathis H, Hufner T, et al. Gap configuration and anteroposterior leg axis after sequential medial ligament release in rotating-platform total knee arthroplasty. Acta Orthop 2006;77:149. 14. Matsueda M, Gengerke TR, Murphy M, et al. Soft tissue release in total knee arthroplasty. Cadaver study using knees without deformities. Clin Orthop Relat Res 1999;366:264. 15. Laskin RS. The Insall Award. Total knee replacement with posterior cruciate ligament retention in patients with a fixed varus deformity. Clin Orthop Relat Res 1996;331:29. 16. Lombardi Jr AV, Nett MP, Scott WN, et al. Primary total knee arthroplasty. J Bone Joint Surg Am 2009;91(Suppl 5):52. 17. Teeny SM, Krackow KA, Hungerford DS, et al. Primary total knee arthroplasty in patients with severe varus deformity. A comparative study. Clin Orthop Relat Res 1991;273:19. 18. Whiteside LA, Saeki K, Mihalko WM. Functional medical ligament balancing in total knee arthroplasty. Clin Orthop Relat Res 2000;380:45. 19. Tanaka K, Muratsu H, Mizuno K, et al. Soft tissue balance measurement in anterior cruciate ligament-resected knee joint: cadaveric study as a model for cruciateretaining total knee arthroplasty. J Orthop Sci 2007;12:149. 20. Aglietti P, Lup D, Cuomo P, et al. Total knee arthroplasty using a pie-crusting technique for valgus deformity. Clin Orthop Relat Res 2007;464:73. 21. Clarke HD, Fuchs R, Scuderi GR, et al. Clinical results in valgus total knee arthroplasty with the “pie crust” technique of lateral soft tissue releases. J Arthroplasty 2005;20:1010. 22. Bellemans J. Multiple needle puncturing: balancing the varus knee. Orthopedics 2011;34:e510. 23. Bellemans J, Vandenneucker H, Van Lauwe J, et al. A new surgical technique for medial collateral ligament balancing: multiple needle puncturing. J Arthroplasty 2010;25:1151. 24. Koh HS, In Y. Semimembranosus release as the second step of soft tissue balancing in varus total knee arthroplasty. J Arthroplasty 2013;28:273. 25. Warren LA, Marshall JL, Girgis F. The prime static stabilizer of the medical side of the knee. J Bone Joint Surg Am 1974;56:665. 26. Warren LF, Marshall JL. The supporting structures and layers on the medial side of the knee: an anatomical analysis. J Bone Joint Surg Am 1979;61:56. 27. LaPrade RF, Engebretsen AH, Ly TV, et al. The anatomy of the medial part of the knee. J Bone Joint Surg Am 2007;89:2000. 28. LaPrade RF, Morgan PM, Wentorf FA, et al. The anatomy of the posterior aspect of the knee. An anatomic study. J Bone Joint Surg Am 2007;89:758. 29. Asano H, Hoshino A, Wilton TJ. Soft-tissue tension total knee arthroplasty. J Arthroplasty 2004;19:558.
Please cite this article as: Koh IJ, et al, How Effective Is Multiple Needle Puncturing for Medial Soft Tissue Balancing During Total Knee Arthroplasty? A Cadaveric Study, J Arthroplasty (2013), http://dx.doi.org/10.1016/j.arth.2013.11.004
