Static knee alignment and its association with radiographic knee osteoarthritis

SummaryObjectivesAlthough knee alignment is associated with the progression of knee osteoarthritis (OA), it is unclear which features that characterize radiographic OA are related to alignment. The aim of this study was to examine the relationship between static knee joint alignment (measured as a continuous variable) and the radiographic features of knee OA (joint space narrowing and osteophytes).MethodsOne hundred and twenty one adults with symptomatic knee OA were recruited using a combined strategy including referral from specialist centres, arthritis support groups and media advertising. X-rays were performed to classify the severity of disease and to determine static knee alignment.ResultsIncreasing varus knee alignment was associated with increasing risk of medial compartment joint space narrowing (P<0.001) and osteophytes (P=0.005). Increasing valgus knee alignment was associated with an increased risk for lateral compartment joint space narrowing (P<0.001) and osteophytes (P=0.002).ConclusionThis study has demonstrated that the static knee angle, measured as a continuous variable, is an important determinant of the compartment-specific features of radiographic knee OA. Further work is required to determine whether interventions aimed at correcting these relatively minor levels of varus and valgus angulation will have an effect on the risk of tibiofemoral OA

The relationship between the angle of the trochlear groove and patella cartilage and bone morphology – a cross-sectional study of healthy adults

SummaryObjectivesAlthough the geometry of the trochlear groove is considered important in the pathogenesis of patellofemoral joint pathology it is unclear how the shape of the trochlear groove relates to patella morphology. This cross-sectional study investigated the relationship between the shape of the trochlear groove and patella cartilage and bone morphology in healthy adults.MethodsTwo hundred and ninety-seven healthy adults aged between 50 and 79 years with no clinical history of knee pain or pathology were examined using magnetic resonance imaging (MRI). From the magnetic resonance (MR) images, the bony angles formed at the distal and proximal trochlear groove were measured, together with patella cartilage and bone volumes and patella cartilage defects.ResultsAfter adjustment for potential confounders, there was an 8.70mm3 (95% confidence interval (CI) 2.15, 15.26) increase in patella cartilage volume (P=0.009), with no increased prevalence of cartilage defects (odds ratio=0.99 (95% CI 0.96, 1.02), P=0.35), for every 1° increase (i.e., as the angle became more flatter) at the distal trochlear groove. Moreover, there was a 53.86mm3 (95% CI −90.26, −17.46) reduction in patella bone volume for every 1° that the angle at the distal trochlear groove became more flattened (P=0.004). No significant association between the proximal trochlear groove angle and the patella cartilage or bone properties was observed.ConclusionA more flattened bony angle at the distal trochlear groove was associated with increased patella cartilage volume and reduced patella bone volume, but no increased prevalence of patella cartilage defects in adults with no history of knee pain or clinical disease. These cross-sectional findings suggest that a flattened distal trochlear groove may protect against degenerative patellofemoral conditions, such as osteoarthritis, but this will need to be confirmed in a longitudinal study