Radiological Decision Aid to determine suitability for medial unicompartmental knee arthroplasty

What is it about?

In patients with moderate to severe arthritis of the knee who have failed non-operative therapy joint replacement is a valid treatment option. Joint replacement can either be a total knee replacement where all the weight bearing surfaces of the knee are replaced, or partial (unicompartmental knee replacement), where just the diseased weight bearing surfaces, typically the inside half (medial) are replaced. In the correct patients partial knee replacement has benefits over total knee replacement including quicker rehabilitation and a more natural feeling knee. However partial knee replacement is not suitable for all knees and this paper reports the development and validation of a Decision Aid based on X-ray assessment which has been designed to determine suitability for partial knee replacement surgery. A total of 457 knees which received knee replacement, either total or partial, at an independent centre were assessed using the Decision Aid and the results were compared to the treatment received which was determined by an experienced surgeon based on history, examination and X-ray assessment. The Decision Aid performed well and was accurate in nine out of ten cases, 90%, based on X-rays alone. When cases where a clear pre-operative plan was made to perform total knee replacement i.e. patient request were excluded the accuracy was 94%. Where the Decision Aid found a patient to be appropriate for partial knee, and they received a partial knee replacement, at five years almost all of implants, 99%, were still functioning well. This study found that the X-ray Decision Aid was safe and could accurately identify patients for partial knee replacement. The widespread use of the Decision Aid should improve patient selection and the results of partial knee replacement.

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