SANG-WON PARK, M.D., SEONG-BEOM HAN, M.D., JONG-HOON PARK, M.D.

Abstract

The purpose of this study is to evaluate the clinical and radiographic results of 20 patients(27 hips) who underwent primary bipolar hemiarthroplasty with non-cemented femoral stem and biarticular cup from January 1989 to April 1999 who were followed for more than nine years. Average follow up was 13.4 years(range: 9~19 years). The type of non-cemented femoral stem was Harris-Galante type in ten hips, Multilock porous coated stem in seven hips, and Multilock porous and tricalcium phosphate coated stem in ten hips. The etiology of osteonecrosis of the femoral head was idiopathic in eleven hips, alcohol abuse in twelve hips and steroid administration in four hips. According to Ficat’s grading system, all twenty-seven hips were in stage. Clinically, we evaluated the Harris Hip scores. We also evaluated the radiographic measurements around the femoral stems and the bipolar cups.

The average Harris Hip score improved from 57.2 points to 89 points; and 2(7.4%)hips were associated with thigh pain and 5(18.5%) hips with groin pain. Around the femoral stem there was progressive radiolucent line more than 1mm in width in 1(3.7%) hip, and osteolysis was present in 9(33.3%) hips. On evaluation of radiographs for stability of fixation, we found that 21 hips(77.8%) showed osseous ingrowth, 5 hips(18.5%) showed stable fibrous ingrowth and one hip(3.7%) showed unstable fixation. The osteolysis around the acetabulum was found in 9 hips(33.3%). Two hips showed evidence of migration of the bipolar cup. Five hips(18.5%) showed acetabular cartilage erosion more than 1mm. Seven hips(25.9%) required conversion to total hip arthroplasties, and in two hips, femoral stems were revised. The causes of failure of bipolar cup was central migration in 2 hips, and dissociation of femoral head, extensive osteolysis, and unknown groin pain after trauma in one each. Two bipolar cups were converted to acetabular cup at revision of the femoral stem. The overall failure rate of the primary operation was 26%. The survivorship of non-cemented femoral stem was 92.6% and 74% in bipolar cup at minimum 9 years follow up.

The current study demonstrated favorable results after bipolar hemiarthroplasties with non-cemented femoral stems. However, the osteolysis around the femoral stems and the acetabular cup emerged as main causes of need for surgical revision.