Fixation of the Quatroloc femoral component: a biomechanical and clinical study

The current study was designed to test the hypothesis that press-fit femoral components with proximal press-fit and distal mechanical interlock can achieve fixation sufficient to allow bone ingrowth in osteoporotic and in normal bone. The addition of steps along the tapered distal stem improved fixation in osteoporotic bone enough to reduce micromotion to less than 20 microm in response to physiologic axial and torsional load. The clinical portion of the study included 226 consecutive hips (223 patients) with 2- to 4-year clinical results after total hip arthroplasty with a rectangular femoral component using proximal porous coating and distal mechanical interlock. Patient age ranged from 36 to 92 years. At 2 years postoperative, 4% of the patients with Type A (normal) femoral bone, 3% with Type B (intermediate) bone, and no patients with Type C (osteoporotic) bone had thigh pain. No clinical cases of loosening have occurred in normal or osteoporotic femurs.