Radiographic outcome after greater trochanteric epiphysiodesis in patients with Perthes disease

Purpose: Legg-Calve-Perthes disease often leads to greater trochanteric overgrowth, which negatively affects the biomechanics of the hip joint. This study aimed to evaluate the physiologic growth of the greater trochanter and the effectiveness of greater trochanteric epiphysiodesis radiographically. Methods: Retrospectively, 46 children (33 male, average age at greater trochanteric epiphysiodesis 8 +/- 1.3 years) with unilateral Legg-Calve-Perthes disease undergoing greater trochanteric epiphysiodesis with screws and curettage of the epiphysis were included. On radiographs of the pelvis pre- and postoperatively (mean follow-up 3.5 years), trochanteric height, articulotrochanteric distance, and center-trochanter distance were determined and compared to the unaffected side. Reference values for the physiological development of trochanteric height, articulotrochanteric distance, and center-trochanter distance over time were established. Results: Greater trochanteric epiphysiodesis reduced trochanteric growth by 29% measured by trochanteric height, but only statistically significant in the group "<8 years" (p = 0.02). Regression analysis revealed inhibition of trochanteric growth of 0.92 mm/year. Both articulotrochanteric distance and center-trochanter distance of the affected and unaffected side converged during the follow-up period: articulotrochanteric distance of the affected hip increased (preop: 11.2 +/- 7 mm, maturity: 18.5 +/- 10 mm; p < 0.01) compared to no change on the unaffected side (preop: 19.3 +/- 5 mm, maturity: 18 +/- 6 mm; p = 0.69). Center-trochanter distance of the affected hip stayed unchanged (preop: (-7.9) +/- 7 mm, maturity: (-7.8) +/- 9 mm; p = 0.13). On the unaffected side, center-trochanter distance became negative (preop: 0.9 +/- 6 mm, maturity: (-6.5) +/- 5 mm; p < 0.001). Measured by articulotrochanteric distance and center-trochanter distance, 31.8% achieved an optimal result. Conclusion: Greater trochanteric epiphysiodesis has a positive effect on greater trochanter growth and therefore on hip anatomy. Further studies must show whether these positive effects also result in biomechanical and functional benefits.