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. 2025 Jun 1;17(6):e85201.
doi: 10.7759/cureus.85201. eCollection 2025 Jun.

Supinated Foot Posture Is Associated With Reduced Knee and Foot Function in Patients With Knee Osteoarthritis

Shingo Mitamura  1 , Akito Kataoka  1 , Hideki Warashina  2
Affiliations

Supinated Foot Posture Is Associated With Reduced Knee and Foot Function in Patients With Knee Osteoarthritis

Shingo Mitamura et al. Cureus. .

Abstract

Objective: This study investigated the difference in lower limb function between supinated and neutral foot postures in patients with knee osteoarthritis (KOA) scheduled for total knee arthroplasty (TKA).

Methods: This study included 62 female patients with KOA knees. Patients were classified into the neutral foot posture group (n = 33 (53%)) and the supinated foot posture group (n = 29 (47%)) using the Foot Posture Index-6 (FPI-6). Femorotibial angle (FTA), knee flexion range of motion (ROM), ankle dorsiflexion ROM, knee extension strength, toe grip strength (TGS), Timed Up and Go (TUG) Test, and knee pain were compared between the two groups.

Results: The supinated foot posture group had significantly lower knee flexion ROM, ankle dorsiflexion ROM, knee extension strength, TGS, and larger FTA than those in the neutral foot posture group. However, no significant differences were observed in TUG or knee pain.

Conclusion: KOA patients with supinated feet have reduced lower limb strength and ROM, suggesting that incorporating foot alignment assessment into KOA rehabilitation is important. However, long-term studies are needed to clarify causal relationships.

Keywords: ankle dorsiflexion rom; femorotibial angle; foot posture index-6; isometric knee extension strength; knee flexion rom; toe grip strength.

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Conflict of interest statement

Human subjects: Consent for treatment and open access publication was obtained or waived by all participants in this study. Nagoya Orthopedic Joint Replacement Clinic Ethics Committee issued approval 202403001. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.

Figures

Figure 1
Figure 1. Flow diagram of the inclusion/exclusion criteria for the analysis
TKA: total knee arthroplasty; FTA: femorotibial angle
Figure 2
Figure 2. Representative photos of feet classified using the FPI-6
FPI-6: Foot Posture Index-6 Supinated foot posture (A): the calcaneus is inverted, the medial longitudinal arch is high, and the medial toes are clearly visible. Neutral foot posture (B): the calcaneus is vertical, the curve above and below the malleolus is identical, and the lateral and medial toes are equally visible. Pronated foot posture (C): the calcaneus is everted, the medial longitudinal arch is in contact with the ground, and the lateral toes are clearly visible
See this image and copyright information in PMC

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