Articular cartilage surfaces and osseous anatomy of the patellofemoral joint in the axial plane

The authors studied the articular joint surface morphology and osseous anatomy of the patellofemoral joint in the axial plane on cryosections from one cadaveric knee and on magnetic resonance arthrotomograms from 30 patients. The cryosectional analysis revealed intraspecimen differences in the articular joint surface geometry and corresponding subchondral osseous morphology of the patella and of the femoral trochlea. On magnetic resonance arthrotomograms, the median ridge of the articular cartilage surface of the patella was located laterally with respect to the corresponding subchondral osseous contour in 19 knees and was located medially in 7 knees. The deepest portion of the articular cartilage surface of the intercondylar sulcus was located laterally with respect to the corresponding subchondral osseous contour of the femoral trochlea in 4 knees and medially in 17 knees. Despite that there was a considerable discrepancy and morphologic variation in the patellofemoral joint geometry among the patients, the hypothesis that the surface of the articular cartilage and corresponding anatomy of the osseous contours match was refuted by the authors' observations of the patella and of the femoral trochlea. The only consistent finding in the anatomic imaging analysis of the patellofemoral joint in the axial plane was a large intra- and interindividual variation of osseous and articular joint surface morphology. Because the osseous anatomy and corresponding articular joint geometry of the patellofemoral joint did not match, magnetic resonance arthrotomography may offer the knee surgeon and the radiologist an accurate insight into the functional congruence/incongruence of opposing articular cartilage surfaces and contact zones of the patellofemoral joint in the axial plane.