Synovial shelves of the knee: association with chondral lesions (SS-42)

Abstract

Even though certain types of the knee plica are well recognized as being pathological, the long-term effects of such plicae upon the articular cartilage have not been quantitatively evaluated. Indeed, the majority of studies regarding plica deal mainly with the acute plica syndrome itself. The objectives of the present study were to evaluate how synovial shelves of the knee might predispose to chondral lesions and to determine which types of the plica are significant risk factors for articular damage. Data was collected prospectively from 1000 consecutive knee arthroscopies. Of the 1000 patients who had knee arthroscopy, 321 (32.1%) patients were found to have knee plicae. The mean age of the patients at the time of the procedure was 37.4 years (33.4 years for the patients with plicae and 39.2 years for the patients without synovial shelves). 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 on a special database. Synovial shelves of the knee were recorded using a modification of the Sakakibara classification (Types A1-D3). Articular lesions were noted on anatomic articular maps of the different functional zones using a system which presaged the current ICRS system. From these maps it was then possible to evaluate the proportions of each articular lesion as well as it’s position. The Outerbridge classification was used for the evaluation of the severity of the cartilage damage. A maximum of the 3 most significant articular lesions was then recorded on the data sheet and subsequently entered into the database. Fisher’s exact test, Pearson chi-square test, t test and Mann-Whitney U test were used for the statistical analysis. All tests were two-tailed with a confidence level of 95% (P < .05). An Increased incidence of articular lesions was found in patients with synovial shelves, in comparison with patients without shelves (94.7% versus 81% respectively; P < .001). Patients with shelves type B2-D3 were found to have increased incidence of cartilage lesions in comparison with patients with type A0-B1 shelves (96.5% versus 86.4% respectively; P = .002), as well as cartilage lesions with bigger size (84% versus 71.4% respectively; P = 0.02). Patella and F2, F3 zones of the medial femoral condyle were areas with increased incidence of cartilage lesions, in patients with synovial shelves in comparison with patients without shelves, with percentages 47.7% versus 27.5% for the patella (P < .001), and 80.2% versus 45% for the F2 and F3 zones (P < .001), respectively. In conclusion, Synovial shelves of the knee are a risk factor for cartilage lesions. Even small shelves with chronic inflammation (type B2-D3) predispose towards more frequent and larger articular lesions. Areas at risk particularly include the patella and the non-weight-bearing medial femoral condyle.