Causes of revision hip arthroplasty after hemiarthroplasty for femoral neck fracture

Background. Hemiarthroplasty as a surgical choice for elderly patients with femoral neck fractures is still a matter of scientific controversy. The aim of the study is to analyse unsatisfactory outcomes of hemiarthroplasty and compare them with the similar outcomes of total hip arthroplasty in elderly patients with femoral neck fractures. Methods. We conducted a retrospective randomized study, which enrolled 36 patients who underwent revision endoprosthetics after various types of arthroplasty for a femoral neck fracture. The patients were divided into 3 groups. Group 1 included 10 patients who underwent arthroplasty with the use of hemiendoprostheses; Group 2 — 15 patients with cemented acetabular components; Group 3 — 11 patients who had cementless acetabular components. Results. The average age of patients in Group 1 at the time of revision arthroplasty was 79 years and was statistically significantly different from the age of patients in Groups 2 and 3 (74.4 and 74.9 years, respectively). The average time for revision interventions after hemiarthroplasty was 40.2 months and significantly differed from the time for the revisions after total cemented (82.7) as well as total cementless (86.6) arthroplasties. The average time for the onset of pain among patients in Group 2 was 68.2 months, and among patients in Group 3 — 71.2 months. The most common bone defects were types 2C and 3A (total of 41.6% in all groups). There were errors in choice of the size of the acetabular bipolar or monopolar component in all 100% of hemiarthroplasty cases. The use of a larger hemiendoprosthesis cup compared to the femoral head led to early erosion of cartilage tissue. Smaller hemiendoprosthesis cups were complicated by early protrusions of the acetabulum floor. The main errors in total arthroplasty were malposition of the acetabular component (33.3-54.5%) and inadequate cement mantle (20%). It should be noted that infections among patients from Groups 2 and 3 developed up to 24.7 months after primary arthroplasty. Conclusions. Errors associated with incorrect choice of the acetabular endoprosthesis component size during primary hemiarthroplasty lead to early complications: erosion and protrusion of the acetabulum. Severe pain syndrome due to incorrect selection of the acetabular hemiendoprosthesis component size develops on average after 13.9 months, and the time period for revision endoprosthetics is 40.2 months after the primary operation. With erosions of the acetabulum, there are no bone defects; with protrusions — bone defects of type 2C and 3A more often occur. In comparison with the outcomes of total hip arthroplasty, the use of hemiendoprostheses shows a low survival rate of 40.2 months.