Acute angle

A 75-year old male patient had been experiencing increasing pain and restricted movement in his left hip over a long period of time. His consultant orthopaedic surgeon, an MDU member, diagnosed severe osteoarthritis of the joint and recommended a hip replacement.

Unfortunately, the patient continued to experience pain in the hip following surgery. He described a feeling of movement of the hip socket. Further radiology showed no evidence of loosening of the prosthesis. X-rays did, however, reveal that the acetabular cup was angled more vertically than normal.

In view of the patient's continuing symptoms and x-ray changes the surgeon performed revision surgery during which it was found that the acetabular cup had prematurely loosened and there was a bony defect in the acetabulum.

The acetabulum was reinforced with an acetabular ring to provide greater stability, but the patient continued to experience difficulties and discomfort in his right hip and underwent a further revision procedure. The patient brought a claim against the surgeon, alleging that the sub-optimal positioning of the prosthesis at the first hip replacement was negligent and that this led to the premature loosening of the prosthesis.

Expert orthopaedic evidence obtained by the MDU advised that the most likely cause of failure of the prosthesis was either mechanical or infective. The expert stated that the angle of the prosthesis was at the upper end of the acceptable range and he was not critical of the position of the prosthesis. There was also no indication that sub-optimal positioning of the prosthesis caused instability of the hip leading to its early failure.

In view of the findings at the revision procedures, the expert thought that the failure of the original prosthesis was more likely to be due to lowgrade infection or aseptic loosening which is the commonest overall risk of hip replacement surgery.

The case was discontinued by the claimant just before going to court. Had the case against the surgeon been successful, and it had been shown that sub-optimal positioning of the cup had led to a premature loosening of the prosthesis, it may well have paved the way for a significant number of similar claims following complications for sub-optimally positioned acetabular cups after hip replacement surgery.

This page was correct at publication on 01/08/2010. Any guidance is intended as general guidance for members only. If you are a member and need specific advice relating to your own circumstances, please contact one of our advisers.