Aims: To determine the anthropometric measurements of bony landmarks in the knee using MR scans and so assist revision knee surgeons in prostheses placement.

Methods: We analysed 100 MR scans of patients aged 16–50 (50 male, 50 female) which were performed for meniscal pathology, patellar dislocation and ACL injury. Those over the age of 50 or with symptoms suggestive of general osteoarthritis, or where the epiphyses had not yet fused were excluded. All measurements recorded were to the level of joint line and are shown below.

Conclusions: To ensure near normal knee mechanics are achieved during revision knee surgery the joint line should be within 5mm of the original. Our study provides mean values for the distance from various bony landmarks to the joint line in non-arthritic knees on MR scan. The use of the medial epicondyle value as a sole reference will place the joint line within 5mm in 88% of males and 96% of females. Use of multiple landmarks further increases accuracy. The final position of the joint will depend on trialling prostheses.