Cementless Total Hip Arthroplasty Using Circumferentially Porous Coated Femoral Stem: Minimum Five-Year Followup Study

Han, Chang Dong; Hahn, Myung Hoon; Park, Jin

Abstract

PURPOSE
The result of more than 5 year follow up after cementless total hip arthroplasty using circumferentially porous coated femoralstem was evaluated. MATERIALS AND METHODS: Eighty five patients (95 hips) were followed more than 5 years after a primary total hip arthroplasty using multilockfemoral stem, which was circumferentially porous coated at the proximal 1/3 of femoral stem. The average age at the time of operation was 48 years. The average duration of followup was 6.9 years. The Harris hip score was used for the evaluation of clinical results. The canal fit of the stem at the proximal canal and isthmus level was evaluated from the postoperative radiographs. The component stability, endosteal bone formation, radiolucent line, osteolysis and polyethylene wear were evaluated from serial followup radiographs. RESULTS: The mean Harris hip scores increased from 60.1 points preoperatively to 91.3 points at the time of the most recent followup. All hips had a press fit at both the proximal canal and isthmus level. On the lastest followup radiograph, endosteal bone formation was observed in all cases (100%). The radiolucent line around the femoral stem was observed in 92 cases (97%), mainly Gruen zones II, III, IV, V and VI. The radiolucent line was thinner than 1 mm and there was no progressive widening. The acetabular osteolysis developed in 31 cases(33%) and the femoral osteolysis in 31 cases (33%) mostly in Gruen zones I, II, and VII. There was no distal osteolysis in the femur. There was no loosening or migration of cup and stem. The mean linear wear was 1.29 (0-5.69) mm and the mean rate of linear wear was 0.18(0-0.81) mm/year. Seventeen hips (18%) were revised for the dissociation of polyethylene liner in 10 hips (11%), excessive wear in the polyethylene liner and progressive osteolysis in 6 hips (6%) and recurence of tuberculous arthritis in 1 hip (1%). CONCLUSION: Cementless total hip arthroplsty using circumferentially porous coated femoral stem showed good medium-term results clinicallyand radiologically, it is likely that circumferential porous coating in the femoral stem induces bone ingrowth and prevents distal osteolysis.