Patella alta and patella infera. Their etiological role in patellar dislocation, chondromalacia, and apophysitis of the tibial tubercle.

The Insall-Salvati method of assessing the position of the patella was applied to four groups of patients:normal patients, and those with dislocation of the patella, chondromalacia of the patella, and apophysitis of the tibial tubercle. The ratio of patellar length to tendon length was 1.0 in the normal patients, 0.8 in the patients with dislocations, 0.86 in those with chondromalacia, and 1.2 in those with apophysitis of the tibial tubercle. Patella alta may be an important cause of dislocating patella and of chondromalacia patellae. The significance of the patella infera found in the Osgood-Schlatter lesion may be one of either cause or effect.