Internal derangements of the knee associated with patellofemoral joint degeneration.

The objective of the present study was to evaluate whether internal derangements of the knee joint are associated with patellofemoral joint (PFJ) degeneration. Data were collected prospectively from 1,000 consecutive knee arthroscopies. Chondral lesions were observed in 854 patients, and these patients were included in this study. Patients' details (age, sex, duration of symptoms, injuries, and possible mechanism of injury), operative details (types and number of portals, equipment used), intra-articular findings (articular, meniscal and synovial lesions, and stability characteristics) and procedures performed were recorded. Articular lesions were noted on anatomic articular maps of the different functional zones, using a system which presaged the current ICRS system. Using this zoning system, it was easy for the authors to separate the patients with isolated patellofemoral degeneration and arthritis and to do the statistical analysis. Increased incidence of isolated patellofemoral degeneration was noted in patients with synovial shelves, in comparison with patients without shelves (24.7% vs. 15.5%, respectively; P=0.001). Patients with severe patellofemoral maltracking were found to have increased incidence of isolated patellofemoral degeneration in comparison with patients without patella maltracking (64.7% vs. 18% respectively; P<0.001). In conclusion, patellofemoral maltracking and synovial shelves of the knee are highly associated with PFJ degeneration. On the contrary, meniscal tears and ligamentous injuries are associated mainly with degeneration of other compartments of the knee joint and not the PFJ.