Objective-Varus and valgus alignment increase, respectively, medial and lateral tibiofemoral load. Alignment was associated with tibiofemoral osteoarthritis progression in previous studies; an effect on risk of incident osteoarthritis is less certain. We tested whether alignment influences the risk of incident and progressive radiographic tibiofemoral osteoarthritis.Methods-In an observational, longitudinal study of the MOST (Multicenter Osteoarthritis Study) cohort, full-limb x-rays to measure alignment were acquired at baseline and knee x-rays were acquired at baseline and 30 months. Varus alignment was defined as ≤ 178° and valgus as ≥ 182°. Using logistic regression and GEE, we examined the association of baseline alignment and incident osteoarthritis at 30 months (in knees without osteoarthritis at baseline), and alignment and osteoarthritis progression (in knees with baseline osteoarthritis). All analyses were adjusted for age, gender, BMI, knee injury, laxity, and extensor strength, with neutral knees as referent.Results-2958 knees (1752 participants) were without osteoarthritis at baseline. Varus (adj. OR 1.49, 95% CI 1.06, 2.10) but not valgus alignment was associated with incident osteoarthritis. 1307 knees (950 participants) had osteoarthritis at baseline. Varus alignment was associated with a greater risk of medial osteoarthritis progression (adj. OR 3.59, 95% CI 2.62, 4.92) and a reduced risk of lateral progression, and valgus with a greater risk of lateral progression (adj. OR 4.85, 95% CI 3.17, 7.42) and a reduced risk of medial progression.Conclusion-Varus but not valgus alignment increased the risk of incident tibiofemoral osteoarthritis. In knees with osteoarthritis, varus and valgus alignment each increased the risk of progression in the biomechanically stressed compartment and reduced the risk of progression in the unloaded compartment.

Objective Varus and valgus alignment are associated with progression of knee osteoarthritis, but their role in incident disease is less certain. Radiographic measures of incident knee osteoarthritis may be capturing early progression rather than disease development. We tested the hypothesis: in knees with normal cartilage morphology by MRI, varus is associated with incident medial cartilage damage and valgus with incident lateral damage. Methods In MOST, a prospective study of persons at risk for or with knee osteoarthritis, baseline full-limb x-rays and baseline and 30-month MRIs were acquired. In knees with normal baseline cartilage morphology in all tibiofemoral subregions, we used logistic regression with GEE to examine the association between alignment and incident cartilage damage adjusting for age, gender, BMI, laxity, meniscal tear, and extrusion. Results Of 1881 knees, 293 from 256 persons met criteria. Varus vs. non-varus was associated with incident medial damage (adjusted OR 3.59, 95% CI: 1.59, 8.10), as was varus vs. neutral, with evidence of a dose effect (adjusted OR 1.38/1° varus, 95% CI: 1.19, 1.59). Findings held even excluding knees with medial meniscal damage. Valgus was not associated with incident lateral damage. Varus and valgus were associated with a reduced risk of incident lateral and medial damage, respectively. Conclusion In knees with normal cartilage morphology, varus was associated with incident cartilage damage in the medial compartment, and varus and valgus with a reduced risk of incident damage in the less loaded compartment. These results support that varus increases the risk for initial development of knee osteoarthritis.

The Multicenter Osteoarthritis Study (MOST) is a longitudinal observational study of the effects of biomechanical, bone and joint structural, and nutritional factors on the incidence and progression of knee symptoms and radiographic and symptomatic knee osteoarthritis (OA). It is the first large-scale epidemiologic study to focus on symptomatic knee OA in a community-based sample of adultswith or at high risk for knee OA, based on thepresence of knee symptoms, history of knee injury or surgery or being overweight. Beginning in 2003, 3026 individuals (60.1% women) age 50-79 years were enrolled. Examinations at baseline, and 15, 30, 60, 72 and 84 months later included assessment of risk factors, disease characteristics, body functions and structure, and measures of physical activity and participation. The wealth of data from this longitudinal cohort of community-dwelling older adults affords valuable opportunities for rehabilitation researchers.

Objective We conducted a cross-sectional study to describe the prevalence of tibiofemoral joint space narrowing (JSN) in medial and lateral compartments and assess whether it differs by gender and ethnic groups, and if it does, to what extent such a difference is accounted for by knee malalignment. Methods The NIH-funded Multicenter Osteoarthritis (MOST) Study is an observational study of persons age 50 to 79 years with either symptomatic knee OA or at high risk of disease. Knee radiographs were assessed for JSN in each tibiofemoral compartment. Mechanical axis angle was measured using full-limb films. We compared the proportion of knees with medial compartment JSN and with lateral JSN between men and women as well as Caucasians (CC) and African Americans (AA) using a logistic regression model adjusting for covariates (race or gender and BMI, age, education, clinic site), and used generalized estimating equations to account for correlation between two knees within a person. Results Of 5202 knees (2652 subjects), 1532 (29.5%) had medial JSN, and 427 (8.2%) had lateral JSN. Lateral JSN was more prevalent in women’s than in men’s knees (OR=1.9, 95% CI 1.5–2.4) and was also higher in knees of AA than in CC (OR=2.4, 95% CI: 1.7–3.3). Further adjustment for malalignment attenuated the OR for gender but not the OR for race. Conclusion Women and AA are more likely to have lateral JSN than men and Caucasians. Valgus malalignment may contribute to the higher prevalence in women.