ABSTRACT
We aimed to find out whether the Hastings bipolar prosthesis moved in a bipolar fashion after its use for displaced fractures of the femoral neck. In 65 patients non-weight-bearing movement was assessed radiographically and compared with an earlier study of the Monk prosthesis. In 70% of patients, the only movement was between the acetabulum and the prosthetic shell, the prosthesis behaving as if it were unipolar. This did not change with time, but there was a slight improvement in the range of movement, particularly in flexion. The absence of movement between the outer shell and the metal head is most probably due to the design of the prosthesis and makes this prosthesis unsuitable for use in osteoarthritic hips.
Subject(s)
Femoral Neck Fractures/surgery , Hip Joint/diagnostic imaging , Hip Prosthesis , Aged , Aged, 80 and over , Evaluation Studies as Topic , Female , Follow-Up Studies , Hip Joint/physiology , Humans , Male , Middle Aged , Movement , Prosthesis Design , RadiographyABSTRACT
Following replacement of the femoral head with the Monk hard-top 'duo-pleet' prosthesis, radiological studies show that movement of the replaced hip takes place between the acetabulum and the metal shell and between the high density polyethylene cup and metal ball. Movements improve with the passage of time. The two sites of movement may contribute to a greater range of hip movement, a better safeguard against loosening and possibly less medial migration of the prosthesis than solid metal prostheses like the Thompson and Austin Moore types.
