Rate of Correction After Temporary Hemiepiphysiodesis: A Focus on the Pathology

Context: Hemiepiphysiodesis has been a successful approach for the management of lower extremity coronal malalignment around the knee. This procedure has reportedly been effective in correcting deformity caused by different pathologies. Aims: This study examines the effect of underlying pathology on the rate of correction following temporary hemiepiphysiodesis. Settings and Design: Records of skeletally immature patients who underwent temporary hemiepiphysiodesis with at least 1-year radiographic follow-up were retrospectively reviewed. Subjects and Methods: Lower extremity mechanical axis deviation (MAD), lateral distal femoral angle (LDFA), and medial proximal tibial angle (MPTA) were measured preoperatively and on the final radiograph obtained before implant removal or before a second procedure was performed on the same limb. Statistical Analysis Used: Rate of change of MAD, LDFA, and MPTA was examined as a function of pathology, deformity direction, age, and body mass index using linear mixed models. Results: One hundred and forty-five patients (257 limbs) were included. The mean ± standard deviation age at surgery was 11.9 ± 3.5 years. The mean rate of correction was 1.48 ± 1.00 mm per month and did not differ based on direction of the initial deformity ( P = 0.55). The mean rate of change in LDFA was 0.29° ± 0.27° per month and MPTA was 0.28° ± 0.26° per month. A faster rate of correction of LFDA and MPTA was noted for younger children ( P < 0.001) and those with rickets ( P < 0.03). A faster rate of correction of MAD showed a trend toward significance for younger children ( P = 0.069). Conclusions: In children with coronal plane deformities treated with guided growth hemiepiphysiodesis, faster correction is expected for children with rickets and younger children.