SURGICAL HIP DISLOCATION AND OSTEOPLASTY SUPPLEMENTED WITH FEMORAL INTERTROCHANTERIC OSTEOTOMY FOR THE TREATMENT OF SYMPTOMATIC HEALED SEVERE SLIPPED CAPITAL FEMORAL EPIPHYSIS

Adolescents with severe slipped capital femoral epiphysis (SCFE) treated with in situ pinning are often found to have a resultant proximal femoral deformity that may cause femoral acetabular impingement (FAI). We performed a retrospective review of our prospectively collected database of symptomatic hips after severe SCFE treated with a surgical hip dislocation, osteoplasty, and an intertrochanteric osteotomy to address the FAI. We hypothesize that this technique offers a safe approach to correct the deformity, improve function and range of motion, while minimizing the risk of osteonecrosis. We have evaluated the clinical and radiographic outcomes of this procedure with a minimum 2 year follow up of all patients. Fifteen patients were treated at our institution from 2017 to 2023. A surgical hip dislocation was performed as previously described by Ganz et al. The osteoplasty is performed by resecting the anterolateral cam lesion to leave a spherical femoral head. All patients underwent further femoral osteotomy due to insufficient range of motion after osteoplasty alone. The degree of derotation performed is based on the amount of internal rotation the patient has at 90% of flexion and neutral adduction after the cam resection. Radiographic parameters were assessed using: articulotrochanteric distance, femoral neck shaft angle, southwick's angle, alpha angle, and center edge angle (CEA) to quantify the degree of deformity and the post operative correction. Clinical outcomes included range of motion and patient reported outcome scores: Nonarthritic hip score (NAHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Hip Outcome Score (HOS) for activities of daily living (HOS-ADL) and Sports Specific Subscale (HOS-SSS), and the Short Form Survey (SF-36) with 9 subscales. All scores were compared from preoperative to latest follow up values. There were fifteen patients with a mean follow up of 44.8 months (range: 24-60). The average osteotomy correction performed in all patients was flexion: 26°, Internal rotation: 31°, and valgus: 15°. Mean range of motion improved as the following: Flexion (pre-op: 93°; latest: 100° (p=0.356)), abduction (pre-op: 22°; latest: 34° (p=0.001)), internal rotation (pre-op: -11°; latest: 29° (p=0.0001)). Patients experienced statistically significant improvements in mean clinical outcome scores including: WOMAC (pre-op: 12.8; latest: 3.9 (p=0.015)), NAHS (pre-op: 80.1; latest: 94.4 (p=0.007)), HOS-ADL (pre-op: 75.3; latest: 97.1 (p=0.006)), HOS-SSS (pre-op: 59.1; latest: 96.8 (p=0.0002)), SF-role limitations (pre-op: 41.7; latest: 87.5 (p=0.02)), SF-social function (pre-op: 63.3; latest: 85.7 (p=0.002)), and SF-pain (pre-op: 66.0; latest: 90.9 (p=0.001)). Radiographically, all patients had statistically significant improvements in the following parameters: Southwick's angle (pre-op: 24°; latest: 6° (p=0.0001)), Alpha angle (pre-op: 77°; latest: 58° (p=0.0003)), and CEA (pre-op: 40°; latest: 34° (p=0.009)). Healed severe SCFE can be safely and effectively treated with a surgical dislocation approach and osteoplasty supplemented with an intertrochanteric osteotomy. Our findings are consistent with literature in providing a safe and effective way to correct the FAI deformity while minimizing the risk of AVN.