112 Original article
Stepwise surgical approach to equinocavovarus in patients with cerebral palsy Sung Hun Wona,*, Soon Sun Kwonb,*, Chin Youb Chungc, Kyoung Min Leec, In Hyeok Leed, Ki Jin Junge, Sang Young Moonc, Myung Ki Chungc and Moon Seok Parkc This study investigated the radiologic results of a stepwise surgical approach to equinocavovarus in 24 patients with cerebral palsy and determined the extent to which each procedure affected radiographic parameters using a linear mixed model. The anteroposterior talus–first metatarsal and anteroposterior talonavicular coverage angles were improved. The calcaneal pitch angle, tibiocalcaneal angle, lateral talus–first metatarsal angle, and naviculocuboid overlap were also improved. The Dwyer sliding osteotomy affected the tibiocalcaneal angle, whereas first metatarsal dorsal wedge osteotomy improved the calcaneal pitch angle and lateral first metatarsal angle. The stepwise surgical approach is effective for correction of equinocavovarus in cerebral palsy patients. J Pediatr Orthop B 25:112–118 Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
Introduction Equinocavovarus deformity is a common disabling foot problem in patients with spastic cerebral palsy. This deformity is found in 38% of patients with the hemiplegic type of cerebral palsy and in 20% of patients with the diplegic and quadriplegic types [1]. It occurs because of the static and dynamic imbalance of the agonist and antagonist muscles that control the foot and ankle joints [2]. It frequently leads to pain when the foot is bearing weight as well as painful callus and ulcerative lesions at the lateral plantar surface [3]. It can also impede normal gait cycle. There are various surgeries for equinocavovarus foot deformity, including soft-tissue release and tendon lengthening or transfer with or without bony procedures such as hind-foot or mid-foot osteotomy or arthrodesis [4–10]. However, the rigidity and complexity of this deformity often requires more radical procedures such as primary triple arthrodesis and occasionally talectomy [8,9, 11]. Gradual distraction techniques using external fixators are reported to be satisfactory for the treatment of this deformity [12]. However, these techniques are not tolerated by patients with spastic cerebral palsy because of the appliances involved; specifically, the spasticity of the disease counteracts the tension of the pins [11,13,14]. Another study also reported good results using a soft1060-152X Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
Journal of Pediatric Orthopaedics B 2016, 25:112–118 Keywords: cerebral palsy, equinocavovarus, linear mixed model, stepwise surgical approach a Department of Orthopaedic Surgery, Armed Force Medical Command, Sungnam, bDepartment of Mathematics, College of Natural Science, Ajou University, Suwon, cDepartment of Orthopaedic Surgery, Seoul National University Bundang Hospital, Sungnam, Kyungki, dDepartment of Orthopaedic Surgery, Sungkyunkwan University Samsung Changwon Hospital, Changwon, Kyungnam and eDepartment of Orthopaedic Surgery, Soonchunhyang University Cheonan Hospital, Cheonan, Chungnam, Korea
Correspondence to Moon Seok Park, MD, Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, 300 Gumi-Dong, Bundang-Gu, Sungnam, Kyungki 463-707, Korea Tel: + 82 31 787 7205; fax: + 82 31 787 4056; e-mail: [email protected] *Sung Hun Won and Soon Sun Kwon contributed equally to the writing of this article.
tissue procedure and triple arthrodesis as part of singleevent multilevel surgery (SEMLS) [11]; however, this method sacrifices joint motion. Furthermore, some studies report a high incidence of osteoarthritis in the remaining foot joints after this procedure [8,15,16]. To our knowledge, there are no guidelines for equinocavovarus foot deformities in cerebral palsy patients undergoing SEMLS. Furthermore, it is difficult to analyze the effects of each procedure on the correction of deformity because of the diversity of surgeries. Accordingly, we developed a stepwise surgical approach with joint preservation for this deformity. Therefore, this study investigated the radiologic results of a stepwise surgical approach to equinocavovarus in patients with cerebral palsy and determined the extent to which each procedure affected radiographic parameters using a linear mixed model (LMM).
Materials and methods This retrospective study was approved by the institutional review board of our hospital (a tertiary referral center for cerebral palsy). The inclusion criteria were as follows: (a) consecutive patients with cerebral palsy who underwent SEMLS, including foot surgery, using a stepwise surgical approach for equinocavovarus foot deformity from February 2003 to November 2012; (b) DOI: 10.1097/BPB.0000000000000244
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Stepwise surgery to equinocavovarus Won et al. 113
Fig. 1
63 patients were screened Equinocavovarus surgery in CP patients Feb 2003 - Nov 2012 Weight-bearing foot radiographs Follow-up for more than 1 year
39 were excluded Prior surgery Inadequate radiograph
9 30
Patient selection
24 patients (29 feet) were included Inclusion and exclusion criteria. CP, cerebral palsy.
patients who had preoperative and postoperative weightbearing anteroposterior and lateral foot radiographs; and (c) patients with more than 1 year of follow-up. The exclusion criteria were as follows: (a) patients with a history of foot surgery and (b) patients with inadequate foot radiographs for measurement (e.g. severe equinus) (Fig. 1). Age, sex, involvement, gross motor function classification system, and the details of concomitant surgery were obtained by reviewing the patients’ medical records. A total of 63 patients with cerebral palsy were followed up for more than 1 year after equinocavovarus foot surgery between February 2003 and November 2012. Thirty patients were excluded because of inadequate radiographs and nine who had undergone a previous foot surgery were excluded. Finally, a total of 24 consecutive patients (18 male and six female patients; total: 29 feet) with cerebral palsy were analyzed. Stepwise approach and surgical techniques
All surgeries were performed by two orthopedic surgeons (blinded) with 24 and 12 years of experience in pediatric orthopedic surgery, respectively, with the same philosophy toward treatment. Foot correction surgery was performed as SEMLS. First, plantar fasciotomy (PF) was performed to correct the cavus component. Cases involving Achilles tightness were subjected to additional tendo-Achilles lengthening. Additional lengthening of the flexor hallucis longus and flexor digitorum longus and posterior capsule release were performed according to the severity of equinus. If hind-foot varus could not be corrected by manual reduction, Dwyer sliding osteotomy with tibialis posterior (TP) split transfer procedures was performed; in correctable cases, soft-tissue procedures (e.g. TP split transfer, TP aponeurotic lengthening, tibialis anterior split transfer, and tibialis anterior aponeurotic lengthening) were performed on a case-by-case basis. If a first metatarsal cavus deformity remained, an
additional first metatarsal dorsal wedge osteotomy was performed; if forefoot adduction remained, an additional double-level osteotomy was performed (Fig. 2). All patients received routine postoperative care and were immobilized with a short leg cast; moreover, they were instructed not to bear weight on the operated foot for 6 weeks after surgery. Standing and weight bearing were resumed with a leaf spring-type ankle–foot orthotic, which was worn for 2 months. The patients were subsequently referred to a local rehabilitation center to continue muscle strengthening exercises and gait training. Foot radiographs in both the anteroposterior and the lateral views were taken by a UT 2000 X-ray machine (Philips Research, Eindhoven, The Netherlands) at a source-to-image distance of ∼ 100 cm with the patient barefoot in the standing position. The radiograph settings were 46–50 kVp and 4.5–5 mAs depending on body size. All conventional radiographic images were digitally acquired using a picture achieving and communication system (PACS; Infinitt, Seoul, Korea) and measurements were subsequently performed using PACS software. Consensus building and measurements
Six orthopedic surgeons (with 24, 12, 9, 7, 5, and 5 years of experience, respectively) held a consensus-building session before measuring radiographs. Previous studies were reviewed, and one of the authors (blinded) pooled the following nine items related to measuring hind-foot varus: talonavicular coverage and anteroposterior talus–first metatarsal angles on anteroposterior radiographs and calcaneal pitch, lateral talocalcaneal, tibiocalcaneal, lateral talus–first metatarsal, and metatarsal stacking angles; naviculocuboid overlap; and medial–lateral column ratio on lateral radiographs [17]. The consensus considered the reliability and validity of the indices of the radiograph to be most important when selecting the indices for analysis.
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114 Journal of Pediatric Orthopaedics B 2016, Vol 25 No 2
Fig. 2
Cavus
Equinus
Plantar fasciotomy
TAL TAL + FHL, FDL TAL + posterior capsular release
Hind foot varus
Fixed
Metatarus primus equinus
Forefoot adduction
Soft tissue procedures (TPST, TAST, TPAL, TAAL)
Flexible
Dwyer sliding osteotomy + soft tissue procedures
First MT dorsal wedge osteotomy
Double level osteotomy
Stepwise surgical approach for correction of equinocavovarus. FDL, flexor digitorum lengthening; FHL, flexor halluces lengthening; MT, metatarsal; TAAL, tibialis anterior aponeurotic lengthening; TAL, tendo-Achilles lengthening; TAST, tibialis anterior split transfer; TPAL, tibialis posterior aponeurotic lengthening; TPST, tibialis posterior split transfer.
Thus, five items were chosen because of their reliability and validity. Furthermore, as we considered the equinus level on radiographs, the tibiocalcaneal angle was also selected. Therefore, six items – calcaneal pitch angle, naviculocuboid overlap, lateral talus–first metatarsal angle, tibiocalcaneal angle, anteroposterior talus–first metatarsal angle, and talonavicular coverage angle – were ultimately chosen according to the consensus of the panel. Calcaneal pitch angle, naviculocuboid overlap, lateral talus–first metatarsal angle, and tibiocalcaneal angle were measured on lateral foot radiographs as described below. The calcaneal pitch angle is the angle between a line drawn along the edge of the plantar soft-tissue shadow and another line drawn along the lower margin of the calcaneus. The naviculocuboid overlap is the overlapping portion of the navicular and cuboid divided by the vertical height of the cuboid. The lateral talus–first metatarsal angle is the angle between a line drawn through the midpoints of the talar head and neck, and another line bisecting the long axis of the first metatarsal bone. The tibiocalcaneal angle is the angle between a line drawn along the lower margin of the calcaneus and another line bisecting the long axis of the tibia. The anteroposterior talus–first metatarsal and talonavicular coverage angles were measured on anteroposterior foot radiographs. The anteroposterior talus–first metatarsal angle is the angle between a line bisecting the anterior articular surface of the talus and another line bisecting the long axis of the first metatarsal bone. The talonavicular coverage angle is the angle between a line bisecting the anterior articular
surface of the talus and another line bisecting the proximal articular surface of the navicular bone. Following consensus building, a reliability test was performed before the main measurements were made. The interobserver reliability of the three orthopedic surgeons (blinded, with 7, 5, and 5 years of experience, respectively) was determined on the basis of intraclass correlation coefficients. The three surgeons assessed radiographs independently and were blinded to the finding of the other surgeons. Four weeks after the measurements were performed by all three surgeons, one of the authors (blinded) repeated the radiographic measurements to assess intraobserver reliability. All radiographic measurements were performed and compared using preoperative and latest follow-up radiographs.
Statistical analysis
Descriptive statistics were used to summarize the patients’ demographics and radiographic measurements. The reliability was assessed on the basis of intraclass correlation coefficients and a two-way random effects model assuming a single measurement and absolute agreement. Preoperative and postoperative radiographic measurements were compared using paired t-tests. For the purpose of statistical independence, only the data from one foot in each patient were included for paired t-tests [18]. Null hypotheses of no difference were rejected if P-values were less than 0.05. All analyses were carried out using SPSS 18.0 for Windows (SPSS Inc., Chicago, Illinois, USA).
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Stepwise surgery to equinocavovarus Won et al. 115
The magnitude of correction after surgery was adjusted by multiple factors using a LMM with age, sex, involvement, and surgical procedures (i.e. PF, Dwyer sliding osteotomy, TP split transfer, and first metatarsal osteotomy) as the fixed effects and each patient and side as the random effect. The estimates were fitted using the restricted maximum likelihood estimation method to produce unbiased estimates. To construct an appropriate model that accounts for the possible additional effects on correction after surgery, multivariate analysis was carried out after univariate analysis.
Table 2
Surgical procedures
Type of procedure Plantar fasciotomy Tendo-Achilles lengthening Posterior capsular release Flexor halluces/flexor digitorum lengthening Dwyer sliding osteotomy Tibialis posterior split transfer Tibialis posterior lengthening Tibialis anterior split transfer Double-level osteotomy First metatarsal dorsal wedge osteotomy Foot medial release
n (%) 14 29 2 2 13 20 3 0 0 14 2
(48) (100) (6) (6) (44) (68) (10) (0) (0) (48 (6)
Results The mean age of the patients at the time of surgery was 17.4 ± 11.4 years and the mean follow-up duration was 2.4 (range, 1.0–8.3) (Table 1). A total of 99 procedures were performed in 24 patients (29 feet) (Table 2). All measurements showed good to excellent interobserver and intraobserver reliability (Table 3). Anteroposterior talus–first metatarsal angle and anteroposterior talonavicular coverage angle improved significantly by 20.9 ± 15.2° and 20.4 ± 17° after surgery (P < 0.001) (Fig. 3). In lateral radiographs, calcaneal pitch angle, tibiocalcaneal angle, lateral talus–first metatarsal angle, and naviculocuboid overlap also improved significantly by 2.3 ± 5.2°, 6.3 ± 10.1°, 3.6 ± 7.7°, and 7.9 ± 14.8°, respectively (P < 0.05) (Table 4 and Fig. 4). The LMM analysis of the effects of each procedure on the correction of equinocavovarus deformity showed that Dwyer sliding osteotomy improved the tibiocalcaneal angle by 9.2° (P = 0.009) (Table 5), whereas first metatarsal dorsal wedge osteotomy improved calcaneal pitch angle by 5.3° (P = 0.01) (Table 5) and the lateral first metatarsal angle by 7.3° (P = 0.04) (Table 5).
Discussion The rigidity and complexity of equinocavovarus deformity often requires more radical procedures such as primary triple arthrodesis and occasionally talectomy. Therefore, this study investigated our stepwise approach surgery for complex equinocavovarus foot on the basis the radiologic results to provide guidelines for the successful correction of these deformities while preserving the joints. In addition, the study determined the effects Table 1
Patients’ demographics
Number/feet Age (years) Sex (M/F) Involvement (unilateral or hemiplegia/bilateral or diplegia) GMFCS level (I/II/III/IV/V) Side (left/right) Follow-up (years) Data are presented as mean (SD).
24/29 17.4 (11.4) 18/6 17/7 11/9/3/1/0 10/19 2.4 (2.0)
of each surgical procedure on the correction of equinocavovarus deformity. The radiologic results show that our stepwise approach surgeries are sufficient to correct complex equinocavovarus foot while not sacrificing joint motion in patients with cerebral palsy. Dwyer sliding osteotomy positively affected the tibiocalcaneal angle, whereas first metatarsal dorsal wedge osteotomy positively affected the calcaneal pitch angle and the lateral first metatarsal angle. Accordingly, we developed a surgical algorithm for the correction of this complex deformity. This study has some limitations that need to be addressed before discussing the results in further detail. First, the primary outcome of our study was radiologic measurement; therefore, we excluded 30 patients who did not have appropriate preoperative standing radiographs because of severe equinus. We believe that if a patient has severe equinus, reliable and objective radiologic measurement would be difficult because most radiographic measurements are accurate in the plantigrade foot position. Thus, future development of objective measurements for foot deformities, such as severe equinus, is needed. Second, Dwyer sliding osteotomy has been used for correction of coronal plane deformities such as hind-foot varus. We found that Dwyer sliding osteotomy positively affected the tibiocalcaneal angle. We hypothesize that Dwyer sliding osteotomy positively effects sagittal alignment by changing the subtalar position. We believe that subtalar motion was influenced by the pronation vector resulting from the effect of Dwyer sliding osteotomy on the weight-bearing position that moved to the lateral aspect owing to lateral sliding. Furthermore, we believe that because equinocavovarus is a three-dimensional deformity, sagittal and coronal parameters influenced each other [17]. Third, we found that first metatarsal dorsal wedge osteotomy positively affected the calcaneal pitch angle and the lateral first metatarsal angle. We believe that because the first metatarsal base is weight bearing, first metatarsal dorsal wedge osteotomy improved the cavus, resulting in a decreased calcaneal pitch angle. In the present study, all six radiographic parameters improved significantly after surgery, especially antero-
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116 Journal of Pediatric Orthopaedics B 2016, Vol 25 No 2
Table 3
Interobserver and intraobserver reliability of radiographic parameters
Radiographic parameters
Interobserver ICC
95% CI
Intraobserver ICC
95% CI
0.901 0.873 0.975 0.848 0.857 0.914
0.862–0.916 0.769–0.938 0.948–0.989 0.765–0.910 0.777–0.892 0.821–0.961
0.993 0.987 0.991 0.991 0.967 0.983
0.986–0.997 0.972–0.994 0.981–0.996 0.980–0.996 0.930–0.985 0.964–0.992
AP talo-1MT AP TN coverage CP TibioCalc Lat talo-1MT NC overlap
AP talo-1MT, anteriorposterior talo-first metatarsal angle; AP TN coverage, anteroposterior talonavicular coverage; CI, confidence interval; CP, calcaneal pitch angle; ICC, intraclass correlation coefficient; lat talo-1MT, lateral talo-first metatarsal angle; NC, naviculocuboid; TibioCalc, tibiocalcaneal angle.
Fig. 3
Fig. 4
(a)
(b)
R Standing
R Standing
(a)
R Standing
Lat talo-1st MT
Talo-1st MT
F Talo-1st MT
R Standing
(b)
Lat talo-1st MT
Preoperative weight-bearing radiograph (anteroposterior view) of a 19-year-old patient’s foot showing equinocavovarus deformity (a). The patient underwent Dwyer sliding osteotomy, first metatarsal dorsal wedge osteotomy with tendo-Achilles lengthening, tibialis posterior splitting transfer, and flexor halluces and digitorum lengthening. Standing AP radiograph at the final follow-up 3 years later shows that the patient’s foot deformity was corrected well comparable with preoperative radiograph (b). AP, anteroposterior.
Table 4
Weight-bearing radiographs (lateral view) from the same patient. Postoperative radiograph (b) shows well corrected compared with preoperative (a). Lat talo-1st MT, lateral talo-first metatarsal angle; talo1st MT, talo-first metatarsal.
posterior parameters. In the past, equinocavovarus foot deformity was treated with triple arthrodesis, which was considered a definitive procedure to create a well-aligned
Change in radiographic measurements after stepwise surgery in patients with cerebral palsy
Parameters
Preoperative
Postoperative
Mean difference
P value
Normal alignment [4]
AP talo-1MT (deg.) AP TN coverage (deg.) CP (deg.) TibioCalc (deg.) Lat talo-1MT (deg.) NC overlap (%)
− 28.3 ± 16.2 − 18.7 ± 18.9 14.5 ± 7.6 71.3 ± 9.3 − 6.4 ± 9.2 6.4 ± 10.2
− 7.3 ± 12.9 1.6 ± 12.9 16.8 ± 8.9 64.9 ± 9.9 − 2.8 ± 9.3 14.4 ± 15.2
− 20.9 ± 15.2 − 20.4 ± 17.0 − 2.3 ± 5.2 6.3 ± 10.1 − 3.6 ± 7.7 − 7.9 ± 14.8
< 0.001 < 0.001 0.04 0.005 0.03 0.01
10 ± 7.0 (− 3 to 28) 20 ± 9.8 (5–39) 17 ± 6.0 (5–32) 69 ± 8.4 (44–86) 13 ± 7.5 (1–35) 47 ± 13.8 (22–85)
The paired t-test was used to evaluate the statistical significance between the preoperative and postoperative measurements. AP talo-1MT, anteriorposterior talo-first metatarsal angle; AP TN coverage, anteroposterior talonavicular coverage; CP, calcaneal pitch angle; lat talo-1MT, lateral talo-first metatarsal angle; NC, naviculocuboid; tibioCalc, tibiocalcaneal angle.
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Stepwise surgery to equinocavovarus Won et al. 117
The linear mixed model analysis on the correction of equinocavovarus deformity
Table 5
Effect
Estimate
P value
95% CI (lower)
Factor affecting postoperative tibiocalcaneal angle Intercept Constant 9.8 Age at surgery Year − 0.3 0.06 − 0.6 Sex Male − 5.5 0.25 − 15.2 Diagnosis Unilateral − 6.1 0.16 − 14.7 Operation PF − 0.9 0.81 − 8.7 9.2 0.009 2.6 Dwyera TPST − 5.3 0.16 − 12.8 First MT DW − 6.3 0.06 − 12.8 Factor affecting postoperative calcaneal pitch angle Intercept Constant 5.4 Age at surgery Year − 0.2 0.22 − 0.4 Sex Male − 2.1 0.48 − 8.0 Diagnosis Unilateral 0.9 0.74 − 4.4 Operation PF − 3.4 0.15 − 8.2 Dwyer − 3.1 0.14 − 7.3 TPST 1.9 0.41 − 2.9 5.3 0.01 1.3 First MT DWb Factor affecting postoperative lateral talo-first metatarsal angle Intercept Constant 4.2 Age at surgery Year 0.07 0.64 − 0.3 Sex Male − 1.2 0.81 − 11.7 Diagnosis Unilateral − 2.2 0.66 − 12.3 Operation PF − 3.7 0.36 − 12.1 Dwyer 2.5 0.46 − 4.4 TPST − 3.8 0.34 −11.7 c 7.3 0.04 0.5 First MT DW
95% CI (upper)
0.01 4.2 2.5 6.9 15.9 2.2 0.1
0.1 3.9 6.1 1.4 1.1 6.7 9.3
procedures for the correction of equinocavovarus foot deformities. Therefore, we used an LMM in which the magnitude of correction after surgery was adjusted by multiple factors such as age, sex, involvement, and surgical procedures (i.e. PF, Dwyer sliding osteotomy, TP split transfer, and first metatarsal dorsal wedge osteotomy) as the fixed effects and each patient and side as the random effect. Dwyer sliding osteotomy positively affected the tibiocalcaneal angle, whereas first metatarsal osteotomy positively affected the calcaneal pitch angle and the lateral first metatarsal angle. Dwyer sliding osteotomy is reported to be a useful procedure for correcting the heel varus component involved in cavus foot deformity [5,20, 21]. In addition, first metatarsal dorsal wedge osteotomy is useful for correcting mid-foot cavus deformity [9,10,22]. Thus, the present results indicate that these procedures produce good postoperative results. In conclusion, the stepwise surgical approach with joint preservation is an effective treatment for correcting equinocavovarus foot deformity in patients with cerebral palsy. In particular, Dwyer sliding osteotomy and first metatarsal dorsal wedge osteotomy combined with softtissue procedures positively affect postoperative radiographic parameters.
0.4 9.3 7.9
Acknowledgements Conflicts of interest
There are no conflicts of interest.
4.5 9.4 4.2 13.9
CI, confidence interval, Dwyer, Dwyer sliding osteotomy; first MT DW, first metatarsal dorsal wedge osteotomy; PF, plantar fasciotomy; TPST, tibialis posterior split transfer. a Factor affecting postoperative tibiocalcaneal angle with statistical significance. b Factor affecting postoperative calcaneal pitch angle with statistical significance. c Factor affecting postoperative lateral talo-first metatarsal angle with statistical significance.
functional foot [15]. Bishay [11] also recently reported good results with triple arthrodesis as part of SEMLS for equinocavovarus deformity in patients with spastic cerebral palsy. However, long-term follow-up studies show a high incidence of osteoarthritis of the remaining foot joints after triple arthrodesis [8,15,16,19]. Furthermore, another study reports complications such neuroarthropathy, pseudarthrosis, residual deformity, mid-foot arthritis, and avascular necrosis of the talus [15]. Therefore, we considered triple arthrodesis for cases of extremely severe cavovarus not correctable by osteotomy, with existing subtalar, talonavicular, and calcaneocuboid joint arthritis. This study also investigated the extent to which each surgery affected radiologic parameters. However, this was difficult to analyze because of the diversity of surgical
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Stepwise surgical approach to equinocavovarus in patients with cerebral palsy Sung Hun Wona,*, Soon Sun Kwonb,*, Chin Youb Chungc, Kyoung Min Leec, In Hyeok Leed, Ki Jin Junge, Sang Young Moonc, Myung Ki Chungc and Moon Seok Parkc This study investigated the radiologic results of a stepwise surgical approach to equinocavovarus in 24 patients with cerebral palsy and determined the extent to which each procedure affected radiographic parameters using a linear mixed model. The anteroposterior talus–first metatarsal and anteroposterior talonavicular coverage angles were improved. The calcaneal pitch angle, tibiocalcaneal angle, lateral talus–first metatarsal angle, and naviculocuboid overlap were also improved. The Dwyer sliding osteotomy affected the tibiocalcaneal angle, whereas first metatarsal dorsal wedge osteotomy improved the calcaneal pitch angle and lateral first metatarsal angle. The stepwise surgical approach is effective for correction of equinocavovarus in cerebral palsy patients. J Pediatr Orthop B 25:112–118 Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
Introduction Equinocavovarus deformity is a common disabling foot problem in patients with spastic cerebral palsy. This deformity is found in 38% of patients with the hemiplegic type of cerebral palsy and in 20% of patients with the diplegic and quadriplegic types [1]. It occurs because of the static and dynamic imbalance of the agonist and antagonist muscles that control the foot and ankle joints [2]. It frequently leads to pain when the foot is bearing weight as well as painful callus and ulcerative lesions at the lateral plantar surface [3]. It can also impede normal gait cycle. There are various surgeries for equinocavovarus foot deformity, including soft-tissue release and tendon lengthening or transfer with or without bony procedures such as hind-foot or mid-foot osteotomy or arthrodesis [4–10]. However, the rigidity and complexity of this deformity often requires more radical procedures such as primary triple arthrodesis and occasionally talectomy [8,9, 11]. Gradual distraction techniques using external fixators are reported to be satisfactory for the treatment of this deformity [12]. However, these techniques are not tolerated by patients with spastic cerebral palsy because of the appliances involved; specifically, the spasticity of the disease counteracts the tension of the pins [11,13,14]. Another study also reported good results using a soft1060-152X Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
Journal of Pediatric Orthopaedics B 2016, 25:112–118 Keywords: cerebral palsy, equinocavovarus, linear mixed model, stepwise surgical approach a Department of Orthopaedic Surgery, Armed Force Medical Command, Sungnam, bDepartment of Mathematics, College of Natural Science, Ajou University, Suwon, cDepartment of Orthopaedic Surgery, Seoul National University Bundang Hospital, Sungnam, Kyungki, dDepartment of Orthopaedic Surgery, Sungkyunkwan University Samsung Changwon Hospital, Changwon, Kyungnam and eDepartment of Orthopaedic Surgery, Soonchunhyang University Cheonan Hospital, Cheonan, Chungnam, Korea
Correspondence to Moon Seok Park, MD, Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, 300 Gumi-Dong, Bundang-Gu, Sungnam, Kyungki 463-707, Korea Tel: + 82 31 787 7205; fax: + 82 31 787 4056; e-mail: [email protected] *Sung Hun Won and Soon Sun Kwon contributed equally to the writing of this article.
tissue procedure and triple arthrodesis as part of singleevent multilevel surgery (SEMLS) [11]; however, this method sacrifices joint motion. Furthermore, some studies report a high incidence of osteoarthritis in the remaining foot joints after this procedure [8,15,16]. To our knowledge, there are no guidelines for equinocavovarus foot deformities in cerebral palsy patients undergoing SEMLS. Furthermore, it is difficult to analyze the effects of each procedure on the correction of deformity because of the diversity of surgeries. Accordingly, we developed a stepwise surgical approach with joint preservation for this deformity. Therefore, this study investigated the radiologic results of a stepwise surgical approach to equinocavovarus in patients with cerebral palsy and determined the extent to which each procedure affected radiographic parameters using a linear mixed model (LMM).
Materials and methods This retrospective study was approved by the institutional review board of our hospital (a tertiary referral center for cerebral palsy). The inclusion criteria were as follows: (a) consecutive patients with cerebral palsy who underwent SEMLS, including foot surgery, using a stepwise surgical approach for equinocavovarus foot deformity from February 2003 to November 2012; (b) DOI: 10.1097/BPB.0000000000000244
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Stepwise surgery to equinocavovarus Won et al. 113
Fig. 1
63 patients were screened Equinocavovarus surgery in CP patients Feb 2003 - Nov 2012 Weight-bearing foot radiographs Follow-up for more than 1 year
39 were excluded Prior surgery Inadequate radiograph
9 30
Patient selection
24 patients (29 feet) were included Inclusion and exclusion criteria. CP, cerebral palsy.
patients who had preoperative and postoperative weightbearing anteroposterior and lateral foot radiographs; and (c) patients with more than 1 year of follow-up. The exclusion criteria were as follows: (a) patients with a history of foot surgery and (b) patients with inadequate foot radiographs for measurement (e.g. severe equinus) (Fig. 1). Age, sex, involvement, gross motor function classification system, and the details of concomitant surgery were obtained by reviewing the patients’ medical records. A total of 63 patients with cerebral palsy were followed up for more than 1 year after equinocavovarus foot surgery between February 2003 and November 2012. Thirty patients were excluded because of inadequate radiographs and nine who had undergone a previous foot surgery were excluded. Finally, a total of 24 consecutive patients (18 male and six female patients; total: 29 feet) with cerebral palsy were analyzed. Stepwise approach and surgical techniques
All surgeries were performed by two orthopedic surgeons (blinded) with 24 and 12 years of experience in pediatric orthopedic surgery, respectively, with the same philosophy toward treatment. Foot correction surgery was performed as SEMLS. First, plantar fasciotomy (PF) was performed to correct the cavus component. Cases involving Achilles tightness were subjected to additional tendo-Achilles lengthening. Additional lengthening of the flexor hallucis longus and flexor digitorum longus and posterior capsule release were performed according to the severity of equinus. If hind-foot varus could not be corrected by manual reduction, Dwyer sliding osteotomy with tibialis posterior (TP) split transfer procedures was performed; in correctable cases, soft-tissue procedures (e.g. TP split transfer, TP aponeurotic lengthening, tibialis anterior split transfer, and tibialis anterior aponeurotic lengthening) were performed on a case-by-case basis. If a first metatarsal cavus deformity remained, an
additional first metatarsal dorsal wedge osteotomy was performed; if forefoot adduction remained, an additional double-level osteotomy was performed (Fig. 2). All patients received routine postoperative care and were immobilized with a short leg cast; moreover, they were instructed not to bear weight on the operated foot for 6 weeks after surgery. Standing and weight bearing were resumed with a leaf spring-type ankle–foot orthotic, which was worn for 2 months. The patients were subsequently referred to a local rehabilitation center to continue muscle strengthening exercises and gait training. Foot radiographs in both the anteroposterior and the lateral views were taken by a UT 2000 X-ray machine (Philips Research, Eindhoven, The Netherlands) at a source-to-image distance of ∼ 100 cm with the patient barefoot in the standing position. The radiograph settings were 46–50 kVp and 4.5–5 mAs depending on body size. All conventional radiographic images were digitally acquired using a picture achieving and communication system (PACS; Infinitt, Seoul, Korea) and measurements were subsequently performed using PACS software. Consensus building and measurements
Six orthopedic surgeons (with 24, 12, 9, 7, 5, and 5 years of experience, respectively) held a consensus-building session before measuring radiographs. Previous studies were reviewed, and one of the authors (blinded) pooled the following nine items related to measuring hind-foot varus: talonavicular coverage and anteroposterior talus–first metatarsal angles on anteroposterior radiographs and calcaneal pitch, lateral talocalcaneal, tibiocalcaneal, lateral talus–first metatarsal, and metatarsal stacking angles; naviculocuboid overlap; and medial–lateral column ratio on lateral radiographs [17]. The consensus considered the reliability and validity of the indices of the radiograph to be most important when selecting the indices for analysis.
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114 Journal of Pediatric Orthopaedics B 2016, Vol 25 No 2
Fig. 2
Cavus
Equinus
Plantar fasciotomy
TAL TAL + FHL, FDL TAL + posterior capsular release
Hind foot varus
Fixed
Metatarus primus equinus
Forefoot adduction
Soft tissue procedures (TPST, TAST, TPAL, TAAL)
Flexible
Dwyer sliding osteotomy + soft tissue procedures
First MT dorsal wedge osteotomy
Double level osteotomy
Stepwise surgical approach for correction of equinocavovarus. FDL, flexor digitorum lengthening; FHL, flexor halluces lengthening; MT, metatarsal; TAAL, tibialis anterior aponeurotic lengthening; TAL, tendo-Achilles lengthening; TAST, tibialis anterior split transfer; TPAL, tibialis posterior aponeurotic lengthening; TPST, tibialis posterior split transfer.
Thus, five items were chosen because of their reliability and validity. Furthermore, as we considered the equinus level on radiographs, the tibiocalcaneal angle was also selected. Therefore, six items – calcaneal pitch angle, naviculocuboid overlap, lateral talus–first metatarsal angle, tibiocalcaneal angle, anteroposterior talus–first metatarsal angle, and talonavicular coverage angle – were ultimately chosen according to the consensus of the panel. Calcaneal pitch angle, naviculocuboid overlap, lateral talus–first metatarsal angle, and tibiocalcaneal angle were measured on lateral foot radiographs as described below. The calcaneal pitch angle is the angle between a line drawn along the edge of the plantar soft-tissue shadow and another line drawn along the lower margin of the calcaneus. The naviculocuboid overlap is the overlapping portion of the navicular and cuboid divided by the vertical height of the cuboid. The lateral talus–first metatarsal angle is the angle between a line drawn through the midpoints of the talar head and neck, and another line bisecting the long axis of the first metatarsal bone. The tibiocalcaneal angle is the angle between a line drawn along the lower margin of the calcaneus and another line bisecting the long axis of the tibia. The anteroposterior talus–first metatarsal and talonavicular coverage angles were measured on anteroposterior foot radiographs. The anteroposterior talus–first metatarsal angle is the angle between a line bisecting the anterior articular surface of the talus and another line bisecting the long axis of the first metatarsal bone. The talonavicular coverage angle is the angle between a line bisecting the anterior articular
surface of the talus and another line bisecting the proximal articular surface of the navicular bone. Following consensus building, a reliability test was performed before the main measurements were made. The interobserver reliability of the three orthopedic surgeons (blinded, with 7, 5, and 5 years of experience, respectively) was determined on the basis of intraclass correlation coefficients. The three surgeons assessed radiographs independently and were blinded to the finding of the other surgeons. Four weeks after the measurements were performed by all three surgeons, one of the authors (blinded) repeated the radiographic measurements to assess intraobserver reliability. All radiographic measurements were performed and compared using preoperative and latest follow-up radiographs.
Statistical analysis
Descriptive statistics were used to summarize the patients’ demographics and radiographic measurements. The reliability was assessed on the basis of intraclass correlation coefficients and a two-way random effects model assuming a single measurement and absolute agreement. Preoperative and postoperative radiographic measurements were compared using paired t-tests. For the purpose of statistical independence, only the data from one foot in each patient were included for paired t-tests [18]. Null hypotheses of no difference were rejected if P-values were less than 0.05. All analyses were carried out using SPSS 18.0 for Windows (SPSS Inc., Chicago, Illinois, USA).
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Stepwise surgery to equinocavovarus Won et al. 115
The magnitude of correction after surgery was adjusted by multiple factors using a LMM with age, sex, involvement, and surgical procedures (i.e. PF, Dwyer sliding osteotomy, TP split transfer, and first metatarsal osteotomy) as the fixed effects and each patient and side as the random effect. The estimates were fitted using the restricted maximum likelihood estimation method to produce unbiased estimates. To construct an appropriate model that accounts for the possible additional effects on correction after surgery, multivariate analysis was carried out after univariate analysis.
Table 2
Surgical procedures
Type of procedure Plantar fasciotomy Tendo-Achilles lengthening Posterior capsular release Flexor halluces/flexor digitorum lengthening Dwyer sliding osteotomy Tibialis posterior split transfer Tibialis posterior lengthening Tibialis anterior split transfer Double-level osteotomy First metatarsal dorsal wedge osteotomy Foot medial release
n (%) 14 29 2 2 13 20 3 0 0 14 2
(48) (100) (6) (6) (44) (68) (10) (0) (0) (48 (6)
Results The mean age of the patients at the time of surgery was 17.4 ± 11.4 years and the mean follow-up duration was 2.4 (range, 1.0–8.3) (Table 1). A total of 99 procedures were performed in 24 patients (29 feet) (Table 2). All measurements showed good to excellent interobserver and intraobserver reliability (Table 3). Anteroposterior talus–first metatarsal angle and anteroposterior talonavicular coverage angle improved significantly by 20.9 ± 15.2° and 20.4 ± 17° after surgery (P < 0.001) (Fig. 3). In lateral radiographs, calcaneal pitch angle, tibiocalcaneal angle, lateral talus–first metatarsal angle, and naviculocuboid overlap also improved significantly by 2.3 ± 5.2°, 6.3 ± 10.1°, 3.6 ± 7.7°, and 7.9 ± 14.8°, respectively (P < 0.05) (Table 4 and Fig. 4). The LMM analysis of the effects of each procedure on the correction of equinocavovarus deformity showed that Dwyer sliding osteotomy improved the tibiocalcaneal angle by 9.2° (P = 0.009) (Table 5), whereas first metatarsal dorsal wedge osteotomy improved calcaneal pitch angle by 5.3° (P = 0.01) (Table 5) and the lateral first metatarsal angle by 7.3° (P = 0.04) (Table 5).
Discussion The rigidity and complexity of equinocavovarus deformity often requires more radical procedures such as primary triple arthrodesis and occasionally talectomy. Therefore, this study investigated our stepwise approach surgery for complex equinocavovarus foot on the basis the radiologic results to provide guidelines for the successful correction of these deformities while preserving the joints. In addition, the study determined the effects Table 1
Patients’ demographics
Number/feet Age (years) Sex (M/F) Involvement (unilateral or hemiplegia/bilateral or diplegia) GMFCS level (I/II/III/IV/V) Side (left/right) Follow-up (years) Data are presented as mean (SD).
24/29 17.4 (11.4) 18/6 17/7 11/9/3/1/0 10/19 2.4 (2.0)
of each surgical procedure on the correction of equinocavovarus deformity. The radiologic results show that our stepwise approach surgeries are sufficient to correct complex equinocavovarus foot while not sacrificing joint motion in patients with cerebral palsy. Dwyer sliding osteotomy positively affected the tibiocalcaneal angle, whereas first metatarsal dorsal wedge osteotomy positively affected the calcaneal pitch angle and the lateral first metatarsal angle. Accordingly, we developed a surgical algorithm for the correction of this complex deformity. This study has some limitations that need to be addressed before discussing the results in further detail. First, the primary outcome of our study was radiologic measurement; therefore, we excluded 30 patients who did not have appropriate preoperative standing radiographs because of severe equinus. We believe that if a patient has severe equinus, reliable and objective radiologic measurement would be difficult because most radiographic measurements are accurate in the plantigrade foot position. Thus, future development of objective measurements for foot deformities, such as severe equinus, is needed. Second, Dwyer sliding osteotomy has been used for correction of coronal plane deformities such as hind-foot varus. We found that Dwyer sliding osteotomy positively affected the tibiocalcaneal angle. We hypothesize that Dwyer sliding osteotomy positively effects sagittal alignment by changing the subtalar position. We believe that subtalar motion was influenced by the pronation vector resulting from the effect of Dwyer sliding osteotomy on the weight-bearing position that moved to the lateral aspect owing to lateral sliding. Furthermore, we believe that because equinocavovarus is a three-dimensional deformity, sagittal and coronal parameters influenced each other [17]. Third, we found that first metatarsal dorsal wedge osteotomy positively affected the calcaneal pitch angle and the lateral first metatarsal angle. We believe that because the first metatarsal base is weight bearing, first metatarsal dorsal wedge osteotomy improved the cavus, resulting in a decreased calcaneal pitch angle. In the present study, all six radiographic parameters improved significantly after surgery, especially antero-
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116 Journal of Pediatric Orthopaedics B 2016, Vol 25 No 2
Table 3
Interobserver and intraobserver reliability of radiographic parameters
Radiographic parameters
Interobserver ICC
95% CI
Intraobserver ICC
95% CI
0.901 0.873 0.975 0.848 0.857 0.914
0.862–0.916 0.769–0.938 0.948–0.989 0.765–0.910 0.777–0.892 0.821–0.961
0.993 0.987 0.991 0.991 0.967 0.983
0.986–0.997 0.972–0.994 0.981–0.996 0.980–0.996 0.930–0.985 0.964–0.992
AP talo-1MT AP TN coverage CP TibioCalc Lat talo-1MT NC overlap
AP talo-1MT, anteriorposterior talo-first metatarsal angle; AP TN coverage, anteroposterior talonavicular coverage; CI, confidence interval; CP, calcaneal pitch angle; ICC, intraclass correlation coefficient; lat talo-1MT, lateral talo-first metatarsal angle; NC, naviculocuboid; TibioCalc, tibiocalcaneal angle.
Fig. 3
Fig. 4
(a)
(b)
R Standing
R Standing
(a)
R Standing
Lat talo-1st MT
Talo-1st MT
F Talo-1st MT
R Standing
(b)
Lat talo-1st MT
Preoperative weight-bearing radiograph (anteroposterior view) of a 19-year-old patient’s foot showing equinocavovarus deformity (a). The patient underwent Dwyer sliding osteotomy, first metatarsal dorsal wedge osteotomy with tendo-Achilles lengthening, tibialis posterior splitting transfer, and flexor halluces and digitorum lengthening. Standing AP radiograph at the final follow-up 3 years later shows that the patient’s foot deformity was corrected well comparable with preoperative radiograph (b). AP, anteroposterior.
Table 4
Weight-bearing radiographs (lateral view) from the same patient. Postoperative radiograph (b) shows well corrected compared with preoperative (a). Lat talo-1st MT, lateral talo-first metatarsal angle; talo1st MT, talo-first metatarsal.
posterior parameters. In the past, equinocavovarus foot deformity was treated with triple arthrodesis, which was considered a definitive procedure to create a well-aligned
Change in radiographic measurements after stepwise surgery in patients with cerebral palsy
Parameters
Preoperative
Postoperative
Mean difference
P value
Normal alignment [4]
AP talo-1MT (deg.) AP TN coverage (deg.) CP (deg.) TibioCalc (deg.) Lat talo-1MT (deg.) NC overlap (%)
− 28.3 ± 16.2 − 18.7 ± 18.9 14.5 ± 7.6 71.3 ± 9.3 − 6.4 ± 9.2 6.4 ± 10.2
− 7.3 ± 12.9 1.6 ± 12.9 16.8 ± 8.9 64.9 ± 9.9 − 2.8 ± 9.3 14.4 ± 15.2
− 20.9 ± 15.2 − 20.4 ± 17.0 − 2.3 ± 5.2 6.3 ± 10.1 − 3.6 ± 7.7 − 7.9 ± 14.8
< 0.001 < 0.001 0.04 0.005 0.03 0.01
10 ± 7.0 (− 3 to 28) 20 ± 9.8 (5–39) 17 ± 6.0 (5–32) 69 ± 8.4 (44–86) 13 ± 7.5 (1–35) 47 ± 13.8 (22–85)
The paired t-test was used to evaluate the statistical significance between the preoperative and postoperative measurements. AP talo-1MT, anteriorposterior talo-first metatarsal angle; AP TN coverage, anteroposterior talonavicular coverage; CP, calcaneal pitch angle; lat talo-1MT, lateral talo-first metatarsal angle; NC, naviculocuboid; tibioCalc, tibiocalcaneal angle.
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Stepwise surgery to equinocavovarus Won et al. 117
The linear mixed model analysis on the correction of equinocavovarus deformity
Table 5
Effect
Estimate
P value
95% CI (lower)
Factor affecting postoperative tibiocalcaneal angle Intercept Constant 9.8 Age at surgery Year − 0.3 0.06 − 0.6 Sex Male − 5.5 0.25 − 15.2 Diagnosis Unilateral − 6.1 0.16 − 14.7 Operation PF − 0.9 0.81 − 8.7 9.2 0.009 2.6 Dwyera TPST − 5.3 0.16 − 12.8 First MT DW − 6.3 0.06 − 12.8 Factor affecting postoperative calcaneal pitch angle Intercept Constant 5.4 Age at surgery Year − 0.2 0.22 − 0.4 Sex Male − 2.1 0.48 − 8.0 Diagnosis Unilateral 0.9 0.74 − 4.4 Operation PF − 3.4 0.15 − 8.2 Dwyer − 3.1 0.14 − 7.3 TPST 1.9 0.41 − 2.9 5.3 0.01 1.3 First MT DWb Factor affecting postoperative lateral talo-first metatarsal angle Intercept Constant 4.2 Age at surgery Year 0.07 0.64 − 0.3 Sex Male − 1.2 0.81 − 11.7 Diagnosis Unilateral − 2.2 0.66 − 12.3 Operation PF − 3.7 0.36 − 12.1 Dwyer 2.5 0.46 − 4.4 TPST − 3.8 0.34 −11.7 c 7.3 0.04 0.5 First MT DW
95% CI (upper)
0.01 4.2 2.5 6.9 15.9 2.2 0.1
0.1 3.9 6.1 1.4 1.1 6.7 9.3
procedures for the correction of equinocavovarus foot deformities. Therefore, we used an LMM in which the magnitude of correction after surgery was adjusted by multiple factors such as age, sex, involvement, and surgical procedures (i.e. PF, Dwyer sliding osteotomy, TP split transfer, and first metatarsal dorsal wedge osteotomy) as the fixed effects and each patient and side as the random effect. Dwyer sliding osteotomy positively affected the tibiocalcaneal angle, whereas first metatarsal osteotomy positively affected the calcaneal pitch angle and the lateral first metatarsal angle. Dwyer sliding osteotomy is reported to be a useful procedure for correcting the heel varus component involved in cavus foot deformity [5,20, 21]. In addition, first metatarsal dorsal wedge osteotomy is useful for correcting mid-foot cavus deformity [9,10,22]. Thus, the present results indicate that these procedures produce good postoperative results. In conclusion, the stepwise surgical approach with joint preservation is an effective treatment for correcting equinocavovarus foot deformity in patients with cerebral palsy. In particular, Dwyer sliding osteotomy and first metatarsal dorsal wedge osteotomy combined with softtissue procedures positively affect postoperative radiographic parameters.
0.4 9.3 7.9
Acknowledgements Conflicts of interest
There are no conflicts of interest.
4.5 9.4 4.2 13.9
CI, confidence interval, Dwyer, Dwyer sliding osteotomy; first MT DW, first metatarsal dorsal wedge osteotomy; PF, plantar fasciotomy; TPST, tibialis posterior split transfer. a Factor affecting postoperative tibiocalcaneal angle with statistical significance. b Factor affecting postoperative calcaneal pitch angle with statistical significance. c Factor affecting postoperative lateral talo-first metatarsal angle with statistical significance.
functional foot [15]. Bishay [11] also recently reported good results with triple arthrodesis as part of SEMLS for equinocavovarus deformity in patients with spastic cerebral palsy. However, long-term follow-up studies show a high incidence of osteoarthritis of the remaining foot joints after triple arthrodesis [8,15,16,19]. Furthermore, another study reports complications such neuroarthropathy, pseudarthrosis, residual deformity, mid-foot arthritis, and avascular necrosis of the talus [15]. Therefore, we considered triple arthrodesis for cases of extremely severe cavovarus not correctable by osteotomy, with existing subtalar, talonavicular, and calcaneocuboid joint arthritis. This study also investigated the extent to which each surgery affected radiologic parameters. However, this was difficult to analyze because of the diversity of surgical
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