LOW-FRICTION ARTHROPLASTY IN SEVERE ACETABULAR DYSPLASIA

Eighty consecutive low-friction arthroplasties in 64 patients with sec ondary arthritis due to severe acetabular dysplasia (Crowe grades III and IV) are analyzed. Two groups of patients were considered. In group I over 20% of the cup was not covered by the acetabulum and was recon structed with a femoral head graft (32 cases; in group 2) a femoral he ad graft was not used because the cup was adequately covered (48 cases ). The mean follow-up period was 9.4 years (range, 3-17 years) for gro up 1 and 8.8 years (range, 3-18 years) for group 2. Early complication s were frequent (19%). To study long-term results only 78 hips were as sessed since two patients were excluded due to deep infection. In thes e 78 hips, group 1 patients showed ''better'' results after 16 years ( 69.6% good results) than group 2 (nongraft procedures) (52:2%), but th ese differences were not significant (P greater-than-or-equal-to .05). Early cup loosening was more frequent in group 2 than in group 1, and good coverage was obtained in 91% of the group 1 cups and in 71% of t he group 2 cups (P greater-than-or-equal-to .05). Acetabular cup loose ning was not correlated with acetabular cup position. Bone-grafts appe ared consolidated in all cases, but resorption areas were frequently o bserved. Radiographic stem aseptic loosening appeared in 10 cases, cor tical hypertrophy in 7 cases, and endosteal osteolysis in 3 cases. Alt hough limb discrepancy was frequent in both groups (75%), the average discrepancy was 1.7 cm.