This retrospective study determined that the outcome from anteromedialization of the tibial tubercle correlates well with the location of patellar articular lesions. Detailed descriptions of patellar articular cartilage lesions were obtained from the operative reports of 36 patients who had anteromedialization performed between February 1984 and March 1994. The patterns fell into four distinct groups. Ten patients with type I (distal) patellar lesions and 13 patients with type II (lateral facet) patellar lesions had 87% good to excellent subjective results, and 100% of these patients said they would have the procedure done again. Nine patients with type III (medial facet) lesions had 55% good to excellent results, and 5 patients with type IV (proximal or diffuse) lesions had only 20% good to excellent results. Patients with type I or II lesions were significantly more likely to have good or excellent results than those with type III or IV lesions. Central trochlear lesions were associated with medial patellar lesions and all patients with central trochlear lesions had poor results. There was no significant correlation between the Outerbridge grading of the patellar lesion and the overall results. Workers' compensation issues diminished the likelihood of a satisfactory outcome by 19%; however, this was not statistically significant. This is the first study to correlate the patellar articular cartilage lesion with outcome after tibial tubercle transfer.