A problematic knee replacement

This case is based on a real scenario, with some facts altered to preserve confidentiality.

A 65-year-old woman complained of pain and reduced mobility in her left knee. Following arthroscopy, which identified significant wear, she opted to proceed with a total knee replacement.

The orthopaedic surgeon used a cemented implant and recorded the procedure as routine. Postoperative x-rays were considered satisfactory and the patient was mobilised, fully weight bearing.

Six weeks following the surgery the patient continued to complain of left knee pain and difficulty in mobilising. On further review by a physiotherapist, it was noted that the left leg was longer than the right. The patient was reviewed again by the orthopaedic surgeon, who concluded that the inequality was unrelated to the prosthesis and that there must have been a pre-existing leg length discrepancy. He advised the patient on appropriate exercises and provided a shoe raise for the right leg.

The patient continued to struggle with ongoing pain and difficulty in walking, requiring the use of two sticks. The surgeon arranged for further imaging. He identified that the angle between the femur and tibia was two degrees rather than the usual six to seven degrees. He explained this was due to the patient having a small stature and narrow pelvis.

The patient was dissatisfied with the outcome of her surgery and requested a second opinion via her GP. The second orthopaedic surgeon found a supine 25 degree valgus deformity with a leg length discrepancy of 2cm. Long leg standing x-rays confirmed there was a valgus deformity of 15 degrees. The second surgeon considered there was a problem with the femoral component of the knee replacement, which had tilted the joint into valgus, giving an apparent leg length discrepancy.

The patient underwent revision surgery approximately eight months following the original procedure. The surgical findings at the second operation included a poorly seated tibial component with a thick cement mantle and the femoral component in excessive valgus.

Following the revision surgery the patient’s symptoms improved. She made a claim against the original surgeon, alleging poor surgical technique that had resulted in ongoing symptoms and the need for early revision.

The second surgeon had been openly critical of the first surgeon in clinic letters to the GP, which were also copied to the claimant. This may have been a factor in the patient’s decision to bring a claim for clinical negligence.

An expert opinion was sought and the claim was settled for a sum in excess of £160,000 because:

• The prosthesis was implanted in valgus malalignment, which was outside the acceptable range.
• The malalignment should have been identified and explained to the patient at an earlier stage, with discussion of options available.
• The tibial cement mantle was overly thick and the tibial component found to be poorly seated at the time of revision surgery.
• The need for revision surgery was primarily related to incorrect positioning of the femoral component at the time of initial total knee replacement.
• It was incorrect to assume the leg length discrepancy identified after the original surgery was a pre-existing problem.

LEARNING POINTS

• If a patient is dissatisfied with the outcome following surgery, listen to and acknowledge their concerns, and establish a mutually agreed plan for ongoing care.
• If a problem is identified, explain to the patient what has been found and how this could potentially be rectified. Seek advice from a colleague if necessary.
• If requested to provide an opinion on a colleague’s work, be mindful of what you say and how it may be interpreted.