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, hip range-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 degrees (range 36-54) compared to 39 degrees 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.