Persistent deficits in knee joint kinematics and kinetics during gait following tibial plateau fractures – a longitudinal study

The recovery process after tibial plateau fractures varies, with some patients experiencing persistent gait asymmetries for a long period of time. The aim of this study is to analyse knee joint kinematics and kinetics post-fracture using a linear mixed-effects model, assessing 26 participants over 24 months (aged 45, range 26-63), and an age-matched control group (aged 47, range 26-62). Participants underwent three-dimensional gait analysis at 6-, 12- and 24-months post-injury. Controls participated in the gait analysis on one occasion. Six gait variables related to knee joint kinematics and kinetics were analysed with a linear mixed-effects model. The model was constructed to determine if there was a differential improvement over time between the injured and the non-injured legs across the six variables, referred to as an interaction effect. If no interaction effect was observed, the model assessed whether there was a side difference between the legs and if there was any improvement over time in both legs. Additionally, non-parametric tests were performed to assess differences between the non-injured leg and the control group across the six variables 24 months after injury. The findings revealed an interaction effect in terms of cumulative absorbed power (p = 0.02, side difference p = 0.06). Other variables showed no interaction effects. Although a side difference between legs was observed for all variables (p < 0.001), only the variables regarding generated power exhibited improvements over time (p = 0.02 respectively). Minimal knee flexion, range of motion, and maximal extending knee joint moment showed no improvements over time. At the 24-month follow-up, the maximal extending knee joint moment was the only variable that differed between the non-injured leg and controls, with increased moment observed for the non-injured leg compared with the controls (p = 0.03). Taken together, two years post-fracture, patients demonstrated pronounced side differences between the injured and non-injured legs with worse ability to extend the knee joint and to generate power in the injured leg. While the kinetic variables improved over time, there were no improvements observed in kinematic variables. Moreover, the non-injured leg performed similarly to healthy controls in terms of minimal knee flexion, range of motion, and generated and absorbed power.