Radiological assessment of the patella position in the normal knee of adult Nigerians.

A method of determining the patella position as described by Insall and Salvati was re-evaluated. Lateral radiographs of 300 normal knee joints were obtained. The length of the ligamentum patella was compared with the longest diagonal length of the patella. Both measurements were found to be approximately equal and the normal variation did not exceed 20%. The ratio of the length of the ligamentum patellae to the diagonal length of the patella was found to be a useful index in determining patella height (position). The clinical value of these measurements is also discussed. It is therefore believed that these ratios irrespective of racial differences, are relatively simple, practical and reproducible. The Insall and Salvati method should therefore be preferred to other previously described methods of determining patella position.