Varus-valgus knee laxity is related to a higher risk of knee osteoarthritis incidence and structural progression: data from the osteoarthritis initiative

No prospective data have confirmed the effect of laxity on the development of KOA, and evidence of the relationship between laxity and KOA progression is still limited. This study aimed to reveal the risk of KOA incidence or progression in no laxity, mild laxity, and severe laxity knees.A total of 3610 knees without radiographic KOA in OAI (osteoarthritis initiative) database were prospectively divided into no, mild, and severe laxity groups to compare KOA incidence in 7-year follow-up via multi-variable Cox regression. Similarly, another 3155 knees with radiographic KOA were analyzed to investigate the effect of laxity on knee replacement surgery, joint space narrowing, malalignment, and pain.The severe laxity group has a higher incidence of KOA (adjusted HR = 1.63, CI = [1.08, 2.47]). Laxity increased the risk of medial joint space narrowing (adjusted OR of mild laxity = 1.36, CI = [1.10, 1.68], adjusted OR of severe laxity = 1.51, CI = [1.06, 2.15]), malalignment (adjusted OR of mild laxity = 1.21, CI = [1.01, 1.45]; adjusted OR of severe laxity = 1.45, CI = [1.05, 2.00]), but had no significant effect on the risk of knee replacement (adjusted HR of mild laxity = 1.19, CI = [0.91, 1.54]; adjusted HR of severe laxity = 1.05, CI = [0.71, 1.54]) or pain (adjusted OR of mild laxity = 1.17, CI = [0.97, 1.42]; adjusted OR of severe laxity = 1.07, CI = [0.75, 1.51]).Compared with no laxity, severe laxity predicts higher KOA incidence in subjects with risk factors. Either mild or severe laxity increases KOA structural progression. Varus-valgus laxity could become a potential predictor and therapeutic target of KOA. Key points • Severe knee laxity predicts higher KOA incidence. • Mild or severe knee laxity increases medial joint space narrowing and malalignment in KOA patients. • Intervention in varus-valgus laxity might be promising in the prevention and management of KOA.