Lateral Pillar Predicts Success of Greater Trochanter Apophyseodesis in Legg-Calvé-Perthes Disease
William Campa, Mason Price, Junichi Tamai, Charles T. MehlmanBackground:
Proximal femur growth requires a dynamic balance between the femoral head, neck, and greater trochanter. Severe Legg-Calvé-Perthes disease (LCPD) disrupts this balance, limiting femoral head and neck growth as the greater trochanter grows normally. This relative overgrowth of the greater trochanter (ROGT) can further impair already compromised hip function. Greater trochanter apophyseodesis (GTA) is a surgical procedure aimed at preventing ROGT and has varying effectiveness depending on disease severity. The purpose of this study was to evaluate the association between disease severity, as determined by the lateral pillar (LP) classification, and ROGT in patients undergoing GTA and to compare outcomes with controls.
Methods:
We retrospectively reviewed 139 patients with unilateral LCPD treated at a single institution between January 1998 and June 2025. Seventy-three patients underwent GTA while 66 served as controls. All patients were followed to skeletal maturity. Patients were stratified by LP classification (B, B/C, C) and age. Radiographic measurements included articulotrochanteric distance (ATD), center-trochanteric distance (CTD), trochanter-to-trochanter distance (TTD), femoral neck length, femoral neck width, and neck-shaft angle to measure proximal femoral morphology. ROGT was defined as an ATD or CTD below the 5th percentile of measurements in unaffected hips. Absolute trochanteric growth inhibition (ATGI) was calculated using TTD measurements to determine the inhibition obtained in each GTA.
Results:
The GTA had the same effect independent of LP class when measured by ATGI. GTA reduced ROGT frequency in LP B and LP C patients compared with controls. However, LP C patients maintained high rates of ROGT after undergoing GTA. LP C patients exhibited significantly shorter, wider femoral necks and smaller neck-shaft angles compared with LP B patients.
Conclusions:
GTA effectively reduces ROGT across LP classifications, independent of age at surgery. However, high rates of ROGT persist in LP C patients despite experiencing similar levels of inhibition through GTA compared with LP B and B/C patients, with proximal femoral measurements suggesting that LP C patients may need additional interventions to overcome growth disturbances observed in severe cases of LCPD.
Levels of Evidence:
Level III—retrospective comparative study.