Treatment of "patellofemoral" cartilage lesions with matrix-assisted autologous chondrocyte transplantation: a comparison of patellar and trochlear lesions.

BACKGROUND: Matrix-assisted autologous chondrocyte transplantation (MACT) has been shown to offer good outcomes at midterm follow-up, but results are heterogeneous among different patients and lesion types. Being part of the same joint, both patellar and trochlear cartilage lesions are commonly considered to be affected by the same treatment issues, and therefore, it is common practice to report results obtained treating these lesions together.
PURPOSE: To determine, in a large cohort of patients prospectively followed at midterm follow-up for patellofemoral chondral defects, if patellar and trochlear defects actually represent different clinical conditions with different healing potentials after cartilage treatment. STUDY
DESIGN: Cohort study; Level of evidence, 2.
METHODS: A total of 49 consecutive patients with full-thickness patellofemoral chondral lesions of the knee were treated with MACT at the authors' institute and followed prospectively for a minimum follow-up of 5 years. Among these 49 patients, 28 were affected by patellar lesions, 17 were affected by trochlear lesions, and 4 had both patellar and trochlear defects. The clinical outcome was analyzed with International Knee Documentation Committee (IKDC) subjective, EuroQol visual analogue scale (EQ-VAS), Kujala, and Tegner scores.
RESULTS: A statistically significant improvement in all scores was observed after treatment. Patellar lesions required more realignment procedures and were more common in women. The comparative analysis showed better results for trochlear lesions compared with patellar lesions at all follow-ups, with mean IKDC scores at 5-year follow-up of 89.6 ± 12.7 and 69.7 ± 17.6, respectively (P < .0005). Better results were also shown for the mean Kujala score (92.4 ± 14.7 vs 81.5 ± 12.7, respectively; P = .012) and mean EQ-VAS score (90.0 ± 10.8 vs 81.9 ± 11.7, respectively; P = .027). Finally, the sport activity level evaluated with the Tegner score confirmed the same trend; even though neither patellar nor trochlear lesion groups reached the preinjury level, both improved after treatment, with a significantly higher improvement in the trochlear lesion group (5.9 ± 1.8 vs 3.9 ± 1.7, respectively; P < .0005).
CONCLUSION: Patient characteristics differ between patellar and trochlear cartilage defects, and moreover, the results obtained are significantly different, with a markedly good outcome in cases with trochlear lesions and less satisfactory results for patients affected by cartilage lesions of the patella. Thus, patellar and trochlear defects should be considered separately when evaluating the outcome of cartilage treatments in this anatomic region.