Undercorrection of planovalgus deformity after calcaneal lengthening in patients with cerebral palsy Byung Chae Cho, MD 1 ; In Hyeok Lee, MD 2 ; Chin Youb Chung, MD 1 ; Ki Jeong Kim, MD 4 ; Ju Seok Ryu, MD 5 ; Kyoung Min Lee, MD 1 ; Soon Sun Kwon, PhD 3 ; Gye Wang Lee, MD 1 ; Myoung Ki Chung, MD 1 ; Moon Seok Park, MD 1 1 Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Gyeonggi, Korea. 2 Department of Orthopaedic Surgery, Sungkyunkwan University Samsung Changwon Hospital, Changwon, Korea. 3 Department of Mathematics, College of Natural Science, Ajou University, Gyeonggi, Korea 4 Department of Neurosurgery, Seoul National University Bundang Hospital, Gyeonggi, Korea 5 Department of Rehabilitation Medicine, Seoul National University Bundang Hospital, Gyeonggi, Korea. OBJECTIVES Calcaneal lengthening(CL) is one of the treatment options for planovalgus deformity in patients with cerebral palsy. However, the its indication still needs to be clarified according to the functional status of cerebral palsy. The aim of this study was to investigate the radiographic outcome after CL in patients with CP and to evaluate the risk factors causing undercorrection of planovalgus deformities. METHODS We included consecutive patients with CP who underwent calcaneal lengthening for planovalgus deformity, were followed for more than two years, and had pre- and postoperative weight-bearing anteroposterior and lateral foot radiographs. Six radiographic indices were used to assess the radiographic outcome. The patient age, sex, and GMFCS level were evaluated as possible risk factors, and we controlled for the interaction of potentially confounding variables using multivariate analysis. RESULTS A total of 44 patients (77 feet) were included in this study. Mean age at the time of surgery was 10.5 ± 4.0 years, and the mean follow-up was 5.1 ± 2.2 years. Patients with GMFCS III/IV was achieved less correction than those with GMFCS I/II in the AP talus-first metatarsal angle (p = 0.001), lateral talocalcaneal angle (p = 0.028) and lateral talus-first metatarsal angle (p < 0.001)(Table 1). The rate of undercorrection in the GMFCS III/IV group was 1.6 times higher than that in the GMFCS I/II group in the AP talus-first metatarsal angle (OR: 1.6; 95% CI: 1.2-2.0; p < 0.001), and 1.6 times higher in the lateral talus-first metatarsal angle (OR:1.6; 95% CI: 1.3-1.9; p < 0.001) (Table 2). CONCLUSIONS We found calcaneal lengthening to be an effective procedure for the correction of planovalgus foot deformities in GMFCS I/II patients with cerebral palsy(Figure 1). However, calcaneal lengthening alone results in a high undercorrection rate in GMFCS III/IV patients with planovalgus deformities(Figure 2). We believe that additional medial column stabilization procedures or alternative procedures should be considered to correct the deformity and to maintain the correction achieved. AP Talus-First Metatarsal Angle Calcaneal pitch angle Lateral Talocalcaneal angle Lateral Talus-First Metatarsal Angle Estimatio n (95% CI) (deg) p value Estimatio n (95% CI) (deg) p value Estimatio n (95% CI) (deg) p value Estimatio n (95% CI) (deg) p value Intercept -16.9 - 4.6 - -16.8 - - Age 0.6 (-0.1 to 1.2) 0.079 -0.2 (-0.7 to 0.3) 0.437 0.7 (0.2 to 1.2) 0.004 1.2 (0.5 to 1.9) <0.001 Sex (male) -1.1 (-6.6 to 4.2) 0.662 3.8 (-0.2 to 7.9) 0.061 -1.0 (-4.8 to 2.8) 0.606 -5.1 (-10.9 to 0.6) 0.077 Side 0.4 1.8 -1.3 -1.4 GMFCS Level I/II (reference) - - - - - - - - Level III/IV 9.1 (3.8 to 14.5) 0.001 -2.0 (-6.0 to 2.0) 0.328 4.3 (0.5 to 8.1) 0.028 10.3 (4.6 to 16.0) <0.001 Table 1. Estimation of the amount of correction AP Talus-First Metatarsal Angle Calcaneal pitch angle Lateral Talocalcaneal angle Lateral Talus-First Metatarsal Angle Adjusted ORs (95% CI) p value Adjusted ORs (95% CI) p value Adjusted ORs (95% CI) p value Adjusted ORs (95% CI) p value Age 1.0 (1.0 to 1.0) 0.688 1.0 (0.9 to 1.0) 0.003 1.0 (1.0 to 1.0) 0.271 1.0 (1.0 to 1.0) 0.158 Sex (male) 1.0 (0.8 to 1.2) 0.807 0.9 (0.7 to 1.1) 0.229 1.0 (0.8 to 1.2) 0.982 1.1 (0.9 to 1.4) 0.363 Side 0.4 1.8 -1.3 -1.4 GMFCS Level I/II (reference) - - - - - - - - Level III/IV 1.6 (1.2 to 2.0) <0.001 1.3 (1.1 to 1.6) 0.009 1.2 (1.0 to 1.5) 0.105 1.6 (1.3 to 1.9) <0.001 Table 2. Potential risk factor for undercorrection *AP = anteroposterior, OR = odds ratio, CI = confidence interval Figure 1. In patients with GMFCS level I/II, the rates of complete correction in AP talus-first metatarsal angle and lateral talus-first metatarsal angle after calcaneal lengthening were both 62.8%. Figure 1 Figure 2. By contrast, in the GMFCS III/IV group these rates were 20.6% in AP talus-first metatarsal angle and 14.7% in lateral talus-first metatarsal angle. Figure 2