Association between lateral patellar osteoarthrosis and knee morphology and alignment in young adults

To assess whether patellar and trochlea morphology and patellar alignment are associated with lateral patellar osteoarthrosis/chondrosis (OAC) in young adults.

Magnetic resonance imaging (MRI) images of 183 subjects (81 cases, 102 controls) aged 21-35 years of age were evaluated. Quantitative measurements of patella and trochlea morphology and patellar alignment were obtained. Axial and sagittal MRI images were reviewed to grade the severity of focal cartilage defects along the lateral facet of the patella. Controls had knees without any abnormalities and were compared to cases with mild and severe lateral patellar OAC. Multivariable logistic regression was used to assess associations between measurements and lateral patellar OAC adjusting for body mass index.

Cases were more likely to have higher Insall-Salvati ratios (OR=350; p<0.001), shorter ratios of the medial to lateral facets of the patella (OR=1.63×10^-3; p<0.001), a shallower (angle closer to 180°) median eminence of the patella (OR=1.063; p=0.009), decreased trochlear cartilage overlap with the patellar cartilage (OR=0.086; p=0.023), and a less angulated lateral patellofemoral angle (OR=0.903; p=0.028), compared to controls. Cases were also more likely to have patellar tendinosis (OR=5.265; p=0.045) and oedema in the superolateral aspect of Hoffa's fat pad (OR=9.872; p<0.001).

Patellar and trochlear morphology and patellar alignment are associated with lateral patellofemoral compartment OAC in young adults.