The association between patella alignment and knee pain and function: an MRI study in persons with symptomatic knee osteoarthritis.

OBJECTIVE

The aim of the study was to examine the association between patellofemoral (PF) alignment (using standard magnetic resonance imaging (MRI) images of extended knees) and knee pain and function.

DESIGN

Subjects were recruited to participate in a natural history study of symptomatic knee osteoarthritis, called the Boston Osteoarthritis of the Knee Study (BOKS). The association of predictive variable (patellar alignment in sagittal and transverse planes) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and function were examined using a linear regression model while adjusting for age, sex, body mass index (BMI), Center for Epidemiologic Studies Depression Scale (CES-D) score and Kellgren and Lawrence score.

RESULTS

Increasing trochlear angle (TA) was associated with both WOMAC (P=0.06) pain and WOMAC function subscale (P=0.04). Increasing lateral patellar title angle (LPTA) and decreasing bisect offset (increasing lateral subluxation) appeared to be associated with increasing WOMAC pain. However, no such an association was observed for other predictors.

CONCLUSIONS

The findings of the present study suggest that increasing TA is associated with increased functional impairment. Other measures of PF malalignment were not significantly associated with either knee pain or functional impairment.