Introduction: Advanced-stage osteoarthritis may occasionally be associated with capital drop of the femoral head. In such cases, excision of the capital drop is performed to obtain good congruency with sufficient coverage of the femoral head by rotational acetabular osteotomy (RAO). In the present study, we examined the outcome of RAO with excision of the capital drop.
Materials and methods: Rotational acetabular osteotomy (RAO) with excision of the capital drop was performed in 17 hips of 16 patients with a mean follow-up of 12.6 years (excision group), while only RAO was performed in 42 hips of 41 patients with a mean follow-up of 12.3 years (non-excision group). All 57 patients indicated radiographic evidence of advanced-stage osteoarthritis. Clinical follow-up was performed using the Merle d'Aubigné and Postel system. The clinical and radiological results were compared between the two groups.
Results: The mean Merle d'Aubigne and Postel's total hip-joint scores at follow up significantly (p < 0.001) improved compared with the mean pre-operative scores only in the non-excision group. While the numbers of hips in excision group (17 hips) showing progressive and non-progressive osteoarthritic changes were 10 and 7, those in the non-excision group (42 hips) were 11 and 20, respectively. Although none (0/17) in the excision group showed any improvement in osteoarthritic stage at follow up, 11 of 42 hips indicated a favorable outcome in the non-excision group. There were significantly (p = 0.0077) higher improvements in osteoarthritis stage in the non-excision than excision group. Three patients each of the excision group (18%) and non-excision group (7%) underwent total hip arthroplasty during the follow-up period.
Conclusion: Excision of capital drop of the femoral head is not a useful adjunct to the RAO procedure for the treatment of advanced osteoarthritis. Based on results from a previous study, Chiari pelvic osteotomy may serve as a more favorable alternative.