Abstract
PurposeLower limb malalignment is a strong predictor of progression in knee osteoarthritis. The purpose of this study is to identify the individual alignment variables that predict progression in early to moderate osteoarthritis of the knee.MethodA longitudinal cohort study using data from the Osteoarthritis Initiative. Intotal, 955 individuals (1329 knees) with early to moderate osteoarthritis (Kellgren-Lawrence grade 1, 2 or 3) were identified. All subjects had full-limb radiographsanalysed using the Osteotomy module within Medicad® Classic (Hectec GMBH) togive a series of individual alignment variables relevant to the coronal alignment of thelower limb. Logistic regression models, with generalised estimating equations wereused to identify which of these individual alignment variables predict symptomworsening (WOMAC score > 9 points) and or structural progression (joint spacenarrowing progression in the medial compartment > 0.7mm) over 24 months.ResultsIndividual alignment variable were associated with both valgus and varusalignment (mechanical Lateral Distal Femoral Angle, Medial Proximal Tibial Angle andmechanical Lateral Distal Tibial Angle). Only the Medial Proximal Tibial Angle wassignificantly associated with structural progression and none of the variables wasassociated with symptom progression. The odds of joint space narrowing progressionin the medial compartment occurring at 24 months increased by 21% for every onedegree decrease (more varus) in Medial Proximal Tibial Angle (p < 0.001)ConclusionsOur results suggest that the risk of structural progression in the medialcompartment is associated with greater varus alignment of the proximal tibia.Level of evidenceLevel III, retrospective cohort study.
Highlights
To moderate knee osteoarthritis (OA) is common, hard to treat and can be debilitating for symptomatic individuals [13]
Standardised coefficients revealed that the scale of effect on varus and valgus alignment was similar for both medial proximal tibial angle (MPTA) and mechanical lateral distal femoral angle (mLDFA)
The most important finding of this study was that a varus MPTA was associated with significant structural progression in subjects with medial compartment knee OA
Summary
To moderate knee osteoarthritis (OA) is common, hard to treat and can be debilitating for symptomatic individuals [13]. These patients are said to be in a “treatment gap” [14] where effective therapeutic interventions are limited. A clear understanding of the predictors that cause structural progression, symptom worsening or non-progression more likely in individuals with symptomatic early to moderate knee OA is necessary. A wide variation in femoral and tibial alignment has been demonstrated in the healthy adult population [11].
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