The results of cementless Zweymüller hip system: 5 to 11 years follow-up study

Objective To analyze the intermediate-term results associated with the use of Zweymüller hip system. Methods Review the 116 cases (142 hips) who were treated with total hip replacement from 1996 to 2002 by a single surgeon using cementless Zweymüller hip systems. Results Sixty-one cases (77 hips) were followed up, 50 cases (64 hips) were evaluated both clinically and radiographically while 5 cases (6 hips) and 6 cases (7 hips) were only evaluated clinically and radiographically respectively. The average follow-up period was 7.3 years(range 5 to 11 years). The mean preoperative Harris Hip Score was 46 while the mean postoperative Harris Hip Score was 93. Distal cortical hypertrophy and medullary sclerosis were observed in 30 hips(42.3%) and 33 hips(46.5%) respectively. Heterotopic ossification arose in 45 hips (63.4%). Radiolucent lines occured in 27 stems(38.0%) but in no cups. Radiolucent lines were mosdy observed in Gruen zones 1. Osteolysis occured in 7 cups (9.9%) and 18 stems (25.4%). Osteolysis was mostly observed in Delee Zone 3 and Green zone 7. In the distal Gruen zones 3, 4 and 5, no radiolucent line or osteolysis was observed. No hips had been revised, 3 cups needed revision surgery because of aseptic loosening. Conclusion The 5-11 years follow-up results are satisfactory, but osteolysis is common