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Saturday, February 26, 2005

ROA helps delay arthritis progression

Treating patients who have hip dysplasia with rotational acetabular osteotomy (RAO) can help prevent progression of osteoarthritis for at least 10 years, according to researchers for Poster P036.

Dysplasia of the hip is the most common cause of secondary osteoarthritis. Hip dysplasia can be treated with a periacetabular osteotomy such as RAO. These procedures have generally produced satisfactory mid- and long-term results, with a few cases of unfavorable results. Researchers evaluated 10-year results to determine the factors of prognostic importance.

The study group of 91 patients (100 hips) had either pre- or early stage arthritis. The mean age at surgery was 36 years (range: 13 to 58 years old). The mean follow-up period was 11 years (range: 8 to 16 years). There were 81 women (89 hips) and 10 men (11 hips).

Clinical follow-up was done using the system of Merle d'Aubigne. Center-edge (CE) angle, articular cartilage (AC) angle and head lateralization index (HLI) were measured on radiographs before the surgery, at 3 months postoperatively and at annual follow-up. Postoperative joint congruencies were classified into four grades: excellent (adequate joint space and nearly identical curvatures of the acetabulum and the femoral head); good (adequate joint space, but not identical curvatures); fair (partial narrowing of joint space) and poor (partial disappearance of joint space).

Overall, the mean clinical score significantly increased from 14 to 17; in only four cases did the mean score decrease. CE angle, AC angle, and HLI significantly improved after surgery.

Progression of osteoarthritis was observed on radiographs at follow-up in seven patients (seven hips). Kaplan-Meier survivorship analysis predicted the rate of prevention of osteoarthritic progression at 10 years as 93 percent. Parametric survivorship analysis using the Cox hazards model indicated that postoperative joint congruency is a risk factor for progression of osteoarthritis.

These findings suggest that RAO is valuable in preventing osteoarthritic progression for at least 10 years. If risk factors can be reduced, a longer operative effect may be expected.

Lead researcher was Yuji Yasunaga, MD, of Hiroshima, Japan.

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