Modified trochanteric triplane osteotomy for chronic moderate to severe slipped capital femoral epiphysis - a preliminary report.

Purpose: Management of chronic moderate and severe slipped capital femoral epiphysis (SCFE) remains controversial. We propose that the modified trochanteric triplane osteotomy(MTTO) with a 130⁰ angled blade plate, without removal of bone wedge, is effective for addressing moderate and severe chronic SCFE.

Methods: A retrospective review was performed on patients who underwent MTTO for moderate to severe chronic SCFE, with at least two years follow-up. Radiological outcomes assessed were osteotomy union, alpha angle, neck shaft angle, mechanical axis deviation and limb length discrepancy(LLD). Functional outcomes were assessed using modified Harris hip score, lower extremity functional scale (LEFS) and SF-36 questionnaire.

Results: A total of 11 patients (13 hips) underwent MTTO for chronic SCFE, with a mean age of 12.9 ± 2.1 years. The pre-operative median modified Harris Hip Score was 73. 12 had severe slip and one had moderate slip. All the osteotomies went on to unite by two months. At an average of 37 months follow up, the mean neck shaft angle was 129⁰, mean alpha angle was 69.7⁰, and mean LLD was 1.05 cm. There was significant improvement in the post-operative modified Harris hip score (p < 0.001), the median post-operative modified Harris hip score was 96, and the median LEFS was 78. One case had bone scan evidence of AVN, but did well with bisphosphonate therapy and one case had a superficial infection.

Conclusion: MTTO is a safe and effective option for addressing deformities in chronic moderate and severe SCFE. However, a residual proximal femoral Cam deformity persists after this procedure which may need to be treated with a simultaneous or a staged osteochondroplasty.