Anterior knee instability caused by anterior cruciate ligament (ACL) deficiency results in meniscal as well as chondral femorotibial and/or femoropatellar damages over a more or less long duration delay. This study’s objectives were, in chronically deficient ACL patients, to assess onset delay for developping chondral patella lesions and also analyse these lesions characteristics in relation to laxity duration.

Chondral patellar lesions in ACL deficient knees get worse with time.

We reviewed 250 charts of patients who had undergone arthroscopically assisted surgery for knee anterior laxity. The arthroscopic procedures were conducted between January 1995 and January 2005. Chondral damages were evaluated at surgery according both to International Cartilage Repair Society (ICRS) and Bauer and Jackson classifications. The data were analyzed using the Kruskal-Wallis test and the Fisher exact test.

Of the 250 analysed charts, 72 patients (28.8%) were found to present chondral patella lesions. The majority of these lesions were superficial and involved the lateral facet area. We observed a statistically significant ICRS worsening grade in relation to laxity duration.

Few publications in the literature report patellar involvement in anterior laxity of the knee. However, our results are comparable to those of the rare series found. The pathomechanics of these lesions has not yet been precisely identified and requires further biomechanical studies.

Patellar damage is frequent with anterior laxity (28.8% in our series) and duration is correlated with statistically significant aggravation of these lesions. Currently, the assessment of these patellar lesions is considered less important than meniscal and femorotibial lesions, even though the natural history of ACL disruption seems to be evolving toward degeneration of all the compartments of the knee, including the femoropatellar compartment.

Level of evidence: level IV. Diagnostic study.