Abstract
Thirty-nine uncemented total hip prostheses were implanted in 34 patients whose mean age was 59.6 years. The patients were evaluated after operation at periodic intervals by two methods: clinically, using the JOA (Japanese Orthopaedic Association) hip rating scale, and radiographically, with serial radiograms at 6 month intervals. At 2 to 4.3 years, the results were excellent (80 to 100 points) in 29 (74%) of the 39 hips, good (70 to 79 points) in 6 (15%), fair (60 to 69 points) in 3 (8%), and poor (less than 60 points) in one (3%) . Factors such as age, degree of obesity, and progression of the disease did not influence the clinical results. Serial radiographic evaluations revealed that radiolucent zones appeared in 14 hips (36%) . The canal fill was determined by calculating the stem diameter (numerator) and diameter of the intramedullary canal (denominator) at three stem levels, and it was significantly lower in those patients with radiolucent zones than in those without them (p<0.01) . The cortical index was determined by calculating the cortical thickness of the femur (numerator) and the femoral diameter (denominator) at three stem levels. It also was significantly lower in those patients with radiolucent zones than in those without them (p<0.01) . The lower incidence of thigh pain in cases with high distal canal fill was significant.
