Altered Foot Progression Angle and Rearfoot Loading in Patellofemoral and Tibiofemoral Osteoarthritis: A Comparative Cross-Sectional Study.

Background: The purpose of this study was to investigate the differences in plantar loading distribution and functional levels between patellofemoral osteoarthritis (PFOA) and tibiofemoral osteoarthritis (TFOA) patients, and to compare them with healthy individuals.

Methods: Sixty patients with knee osteoarthritis and 30 age-matched, healthy individuals (control group) were included in the study. The patients were divided into two groups, the PFOA group (n = 31) and the TFOA group (n = 29), based on the Kellgren Lawrence classification system. The maximum foot pressure of the foot (FPmax), forefoot weight ratio, rearfoot weight ratio, total load on foot, and foot progression angle (FPA) were determined by pedobarographic analysis. Functional level was assessed with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).

Results: There was a significant difference in FPA (F(2,79) = 22.322, P < .001) and rearfoot weight ratio (F(2,77) = 7.694, P = .001) among the groups. The FPA in the PFOA group was lower than in the TFOA group (P <. 001). The rearfoot weight ratio was higher in the PFOA group than in the TFOA group (P <. 05). No significant difference was found in FPmax (P = .457), forefoot weight ratio (P = .183), and total load on the foot (P = .226) among the groups. Also, no difference was found in the WOMAC total score and subscales between the PFAO and TFAO groups (P > .05).

Conclusions: The results suggest that the FPA and rearfoot loading were altered in patients with PFOA compared to those with TFOA and healthy individuals. Clinicians need to consider the effect of altered foot position and loading on the knee biomechanics in their treatment approach regarding foot orthoses or gait modification in patients with PFOA.