Normal function of the patellofemoral joint is maintained by a complex interaction between soft tissues and articular surfaces. No quantitative data have been found on the relative contributions of these structures to patellar stability. Eight knees were studied using a materials testing machine to displace the patella 10 mm laterally and medially and measure the force required. Patellar stability was tested from 0° to 90° knee flexion with the quadriceps tensed to 175 N. Four conditions were examined: intact, vastus medialis obliquus relaxed, flat lateral condyle, and ruptured medial retinaculae. Abnormal trochlear geometry reduced the lateral stability by 70% at 30° flexion, while relaxation of vastus medialis obliquus caused a 30% reduction. Ruptured medial retinaculae had the largest effect at 0° flexion with 49% reduction. There was no effect on medial stability. There is a complex interaction between these structures, with their contributions to loss of lateral patellar stability varying with knee flexion.

We have developed a list of 281 competencies deemed to be of importance in the training of orthopaedic surgeons. A stratified, randomised selection of non-university orthopaedic surgeons rated each individual item on a scale 1 to 4 of increasing importance. Summary statistics across all respondents were given. The mean scores and sds were computed. Secondary analyses were computed in general orthopaedics, paediatrics, trauma and adult reconstruction. Of the 156 orthopaedic surgeons approached 131 (84%) responded to the questionnaire. They rated 240 of the 281 items greater than 3.0 suggesting that competence in these was necessary by completion of training.

Complex procedures were rated to be less important. The structure, delivery and implementation of the curriculum needs further study. Learning activities are ‘driven’ by the evaluation of competencies and thus competency-based learning may soon be in the forefront of training programmes.