Background/Purpose: Disturbances of weight bearing and walking pattern occur in patients with knee osteoarthritis (OA) due to impairments in knee joint. These impairments may lead to changes in the mechanical alignment of lower limb and dynamic function of the foot. Therefore, it has been given special attention to foot orthoses and footwear modifications as a non-operative treatment of knee OA. However, in order to fully understand the effect of these interventions on the knee and other lower limb joints, greater knowledge of foot structure is required. We aimed to study the plantar pressure and foot posture characteristics of knee OA and their relationship with disease characteristics.

Methods: A total of 78 feet of 39 patients with bilateral knee OA (ACR criteria) were evaluated regarding clinical and biometrics data. Demographic and disease characteristics were obtained. The radiographical evaluation was done based on anterior–posterior tibio-femoral radiographs using the Kellgren–Lawrence (KL) grading scale (0–4). Barefoot dynamic plantar pressure and the Arch index (AI) were measured by the 3D footscan system. The Foot posture index (FPI-6) was obtained. Correlation (Pearson’s correlation coefficient) and regression analyses were performed between various plantar pressure analysis, clinical parameters and disease-related parameters.

Results: Thirty nine patients (11 male) with mean age 51,53 (standard deviation (SD):11,89) and mean BMI 30,5 (SD:4,9) were recruited. For dynamic plantar pressures; grade in right knee according to KL radiologic criteria correlates with left foot medial heel, left midfoot and left middle forefoot pressures (r=0,40, p=0,010; r=0,33, p=0,040; r= 0,36, p=0,022 respectively). Grade in left knee according to KL radiologic criteria correlates with left heel, left midfoot and inversely correlates with right foot toe pressure (r=0,33, p=0,036; r=0,41, p=0,010; r=-0,41, p=0,009 respectively). For foot posture; grade in right knee according to KL radiologic criteria correlates with right FPI-6, grade in left knee according to KL radiologic criteria correlates with left FPI-6, right FPI-6 and left AI (r=0,38, p=0,015; r=0,41, p=0,008; r=0,41, p=0,009; r=0,33, p=0,036 respectively). In multivariate regression analysis it is found that left KL grade was most affected from left AI (p=0,045)

Conclusion: The dynamic variables of plantar pressure and foot posture are sensitive to the OA grading. These results suggest that people with the higher OA grade exhibit a more pronated foot type and shifted pressure distribution. We can maintain a superior biomechanical correction by advanced evaluation of foot structure in non-operative treatment of knee OA such as orthoses and footwear modifications. As a result, the assessment of patients with knee OA in clinical practice should include simple foot measures and evaluation.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/evaluation-of-foot-posture-and-plantar-pressure-changes-in-knee-osteoarthritis-preliminary-report/