gms | German Medical Science

Objectives: To determine any association between geometry parameters of the patellofemoral joint measured on Magnetic Resonance Images (MRI) and patellar chondral defects.

Methods: In this prospective study, 64 patients (18 female, 46 male, mean age 37.4±3.1) with arthroscopically seen chondral patellar defects (stage III and IV according to Outbridge classification) were participated. These patients were compared with 48 other patients who sustained meniscal injury but without patellar cartilage defects and treated arthroscopically. MRI views of all patients were analysed preoperatively with regard to patella facet angle, sulcus angle, lateral trochlear inclination, trochlear facet ratio, congruence angle, patella tilt and patella height. Patellar chondral defects were correlated to aforementioned geometry parameters. Statistical packet STATA 8.0 was used to analyse the data and significance was set at p<0.05.

Results and Conclusion: Stepwise regression analysis revealed that trochlear depth < 12mm (p = 0.032), sulcus angle >150 ° (p=0.034), lateral trochlear inclination < 11° (p = 0.038), trochlear facet ratio of less than 40% (p = 0.041), and higher Insall-Salvati index (p = 0.045), are significantly associated with patellar chondral defects.

Patellar chondral defects are associated with specific radiographic indices seen in MRI. These parameters must be taken into consideration when cartilage repair surgery is recommended.