Study Purposes: A retrospective study to assess patient’s height as a predictor for sizing the femoral component of the Phase 3 Oxford Unicompartmental Knee replacement.

Methods and Results: 118 patients post oxford uni-compartmental knee replacement were identified from the elective orthopaedic unit. Their post-operative radiographs were reviewed by 3 independent orthopaedic surgeons according to the Oxford Group criteria, measuring the femoral component fit. Patients were allocated to two cohorts: patients with ill-fitting prostheses and well fitting prosthesis.

Patient’s height and size of femoral component used at time of surgery was recorded. The results showed a positive correlation between the patient’s height and a well fitting femoral prosthesis.

Conclusions: Current templates with the Oxford Phase Three system may not provide accurate guide to the correct femoral prosthesis size for a patient. Recent studies have highlighted the wide range of magnifications used in computerised X-ray systems leading to variance with templating. Other studies have shown large inter-observer variability when sizing the femoral component. A variable as simple as patient height may offer a more accurate guide for choosing the size of the femoral component.

We have demonstrated that the height of a patient can be a used to guide and assist in the sizing of the femoral component of the Oxford uni-compartmental knee replacement. This study may also have implications for the sizing of other prostheses currently in use.