Two approaches to evaluate the associations between patellofemoral joint alignment, morphology, radiographic osteoarthritis and anterior knee pain: the most study

Abstract

Purpose: To evaluate the cross-sectional associations between patellofemoral joint alignment, trochlear morphology, radiographic osteoarthritis (OA), and frequent isolated anterior knee pain (AKP). Methods: We evaluated participants from the Multicenter Osteoarthritis Study (MOST), a cohort of 3026 individuals aged 50 - 79 years who had, or were at risk of, knee OA at enrollment. At the 60-month visit, we assessed patellar alignment and trochlear morphology from MR images (bisect offset , patellar tilt angle, sulcus angle, lateral trochlear inclination, medial trochlear inclination, trochlear angle) or lateral radiographs (Insall-Salvati ratio). Radiographic OA was defined on the lateral view (patellofemoral) as any osteophyte ≥ Grade 2, or joint space narrowing ≥ Grade 2 plus any osteophyte, sclerosis or cyst ≥ Grade 1; and OA on the postero-anterior view (tibiofemoral) radiographs was defined as Kellgren & Lawrence ≥ Grade 2. Frequent isolated AKP was defined as: (i) a response of ‘yes’ to the question “During the past 30 days, have you had pain, aching, or stiffness in your knee on most days?”; and (ii) the pain was reportedly isolated to the anterior knee region using a knee pain map. We used two different study designs. Our first design was a within-person, knee-matched evaluation of participants with frequent isolated AKP in one knee and no pain in the other knee (conditional logistic regression). We selected individuals with unilateral knee pain at the 60-month visit, or at the 84-month visit if they did not meet these criteria at 60 months. Our second design was a traditional cohort approach using data from the 60-month study visit, in which we evaluated the relation of the various exposures to presence of frequent isolated AKP to knees without pain (binomial regression). Results: The within-person knee-matched design (n=110, 64% women, mean [SD] age 70 [8], BMI 30.9 [6.3]) revealed no associations between patellofemoral alignment, morphology, or tibiofemoral OA and frequent isolated AKP. Patellofemoral OA was associated with frequent isolated AKP, odds ratio 5.3 (95% CI 1.6, 18.3) (see Table 1). The cohort design (n=1818, 59% women, age 68 [8], BMI 30.4 [5.9]) revealed similar results: only patellofemoral OA was associated with frequent isolated AKP, prevalence ratio 2.2 (1.4, 3.4) (see Table 2). Conclusions: Patellofemoral alignment and trochlear morphology were not associated with frequent isolated anterior knee pain in individuals with, or at risk for, knee OA. Radiographic patellofemoral OA, but not tibiofemoral OA, was associated with frequent isolated anterior knee pain. Features of patellofemoral OA, more so than mechanical alignment or morphology features or tibiofemoral OA, may contribute to localized anterior knee pain.View Large Image Figure ViewerDownload Hi-res image Download (PPT)