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Friday, February 25, 2005

Study: femoral osteotomy improves results of cementless THA in patients with DDH

The distorted anatomy in patients with developmental dysplasia of the hip (DDH) makes a total hip arthroplasty (THA) a challenging procedure. However, femoral shortening and derotation at the subtrochanteric zone can be helpful in improving primary stability and consolidating the osteotomy, according to researchers for poster exhibit P086.

Eleven adults with DDH (Crowe types III and IV) were treated with cementless THA. The cup was implanted at the anatomic height. The femoral canal was broached, respecting its proximal flare. Subsequent to preparation of the canal, surgeons resected and derotated a femoral segment at the subtrochanteric zone. The anatomy of the femoral canal combined with the external rotation allowed surgeons to match the stem in a very stable position in nine patients (82 percent), who then required no or minimal additional fixation. After a mean follow-up of 42 months (range: 25 to 81 months), these patients showed no radiographic signs of loosening. Neither were there any revisions in this group.

Functional assessments were based on the Harris hip scoring system, and radiologic assessments were based on the DeLee, Charnley, Gruen zones and the Engh criteria. The mean Harris hip score improved from 36 to 82 points and the mean leg-length discrepancy was reduced from 8 cm to 1.5 cm. Union was achieved in all cases in a mean of 10 weeks (range: 8 to 14 weeks).

Based on these results, researchers noted that femoral shortening and derotation performed after the canal has been prepared create a primary stability next to the metaphyseal zone. This permits early weightbearing, which favors early consolidation.

Researchers included: Marco A. Telöken, MD; Paulo David F. Gusmăo, MD; Marcus V. Crestani, MD; Patrick E. Telöken, MS, and Felipe Diligenti, MS, all of Porto Alegre, Brazil.

Illustration of the steps involved in femoral osteotomy of patients with DDH.

Preoperative and postoperative radiographs showing results of cementless THA with femoral osteotomy.

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