Bipolar Hemiarthroplasty Using Non-cemented Multilock Femoral Stem: A 7-year Minimum Follow-up Study

Park, Sang Won; Lee, Soon Hyuck; Han, Seung Bum; Jeong, Woong Kyo; Kim, Sang Beom; Yang, Jae Hyuck; Choi, Keun Seok

Abstract

Purpose
To evaluate the clinical and radiographic results of primary bipolar arthroplasty during average 9.8-year period, using a non-cemented Multilock femoral stem and a biarticular acetabular cup. Materials and Methods: This study included 24 patients (29 hips) who underwent primary bipolar hemiarthroplasties with Multilock femoral stems and biarticular cups and who could be followed for more than seven years. Clinically, we evaluated the Harris Hip scores and patient complaints of thigh and inguinal pain. We also evaluated the radiographic measurements around the femoral stems and the bipolar cups. Results: The average Harris Hip score improved from 57.4 points to 91.6 points; and 3 (10.3%) hips were associated with thigh pain and 4 (13.8%) hips with inguinal pain. Around the femoral stem there was a non-progressive radiolucent line less than 1 mm in length in 4 (13.8%) hips and osteolysis was present in 6 (20.6%) hips. With respect to the stability of the fixations, there was osseous ingrowth in 26 (89.7%) hips and fibrous ingrowth in 3 (10.3%) hips. Around the acetabulum there was osteolysis in 5 (17.2%) hips, proximal migration of the cup in 2 (6.9%) hips, and erosion of the acetabular cartilage in 10 (34.5%) hips. There were 3 (10.3%) biarticular cups, which were converted to total hip arthroplasties, but no femoral stems were revised. The overall failure rate of the primary operations was 10.3%. Conclusion: The current study demonstrated favorable results after bipolar hemiarthroplasties with Multilock femoral stems. However, the osteolysis that occurred around the femoral stems and the acetabula emerged as a problem after the total hip arthroplasties. In particular, it is expected that the osteolysis would increase over time and become the main cause for the need for surgical revision.