Treatment of severe late-onset Perthes' disease with soft tissue release and articulated hip distraction: Revisited at skeletal maturity

Purpose: Late-onset Perthes' disease is diagnosed after 9 years of age. Conservative treatment and conventional surgical techniques have limited ability to reduce the pressure in the joint or change the shape of the femoral head. We used a combination of soft tissue release and joint distraction with a hinged mono-lateral external fixator for these patients. Ten of our patients reached skeletal maturity and were evaluated. Methods: Clinical assessment included: Harris hip score, hiprange-of-motion (ROM), limb length discrepancy, and the Oxford hip questionnaire for pain and function. Radiographic assessment included: Sharp transverse acetabular inclination, the uncoverage percentage, the epiphyseal index before surgery (modified Eyre-Brook), at frame removal, and, at last follow-up, the epiphyseal quotient (of Sjovall) and the Stulberg classification. Results: Our study included eight boys and two girls (mean age at surgery 12.3 years, range 9.4-15.1, mean age at last follow-up 18.1 years, range 15.2-22.8). The mean follow-up was 5.7 years (range 4.3-7.8). The mean Harris hip score was 86.3/100 (range 48.5-96); one patient had <85 points. The hip ROM was slightly limited in most patients, and seven patients had limb shortening between 1-4 cm. The mean Oxford hip questionnaire score was 17.4/60 (range 12-31). The mean Sharp transverse acetabular inclination of the affected side was 42° (range 36-54) compared to 39° for the unaffected side (P = 0.045). The mean uncoverage percentage was 37% (range 27-47) compared to 20% for the unaffected side (P = 0.017). The mean epiphyseal index was 0.71 (range 0.31-0.92) before surgery, 0.79 (range 0.50-0.93) at frame removal (P = 0.012), and 0.72 (range 0.51-0.89) at last follow-up (P = 0.646). The epiphyseal quotient for the eight unilateral cases was 0.72 (range 0.49-0.91), and the Stulberg classification was type III for three cases and type IV for seven. Conclusion: Patient satisfaction for function and pain following the combined procedure was good. Radiographic parameters did not change significantly. This should be regarded as a salvage procedure.