THU0738-HPR Comparison of the functional profile of the foot between the patients with patellofemoral osteoartritis and tibiofemoral osteoarthritis
Authors: N.B. Sari, H. Güney Deniz, G. Baltaci
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> The biomechanics of the patellofemoral (PF) joint are distinct from the tibiofemoral (TF) joint and hence, interventions that have been designed to reduce pain and improve function in those with tibiofemoral disease may be inappropriate for those with Patellofemoral OA (PFOA). Therefore, patients with PFOA have been recently considered a subgroup different from patients with Tibiofemoral OA (TFOA). Loading asymmetries of the foot, discrepancy in foot contact area, and excessive increase in plantar pressure are associated with knee OA patients but there is lack of information that how PFOA or TFOA affect the foot profile. <h3>Objectives</h3> The purpose of this study was to investigate the foot profile differences between PFOA and TFOA patients and also compare these foot profiles with healthy individuals. <h3>Methods</h3> Twenty-nine patients with unilateral knee OA and 14 age-matched controls (median age=42.5 years, median BMI=23.8 kg/m<sup>2</sup>) were included in the study. The patients were divided into two groups; PFOA group (n=16, median age=52.5 years, median BMI=26.7 kg/m<sup>2</sup>) if they had a radiographic Kallgren and Lawrence (KL) score grade 2 or 3 in the PF joint, which was greater than KL score for the TF compartments; TFOA group (n=13, median age=54 years, median BMI=26.6 kg/m<sup>2</sup>) if they had a radiographic KL score grade 2 or 3 in the TF joint, which was greater than KL score for the PF compartments. Plantar pressure distribution was recorded by Digital Biometry Scanning System and Milletrix software (DIASU, Italy). The static test was used to determine the maximum foot pressure (N/cm<sup>2</sup>) of the foot, forefoot weight ratio, rarefoot weight ratio, total load and foot angle axis (FAA). Kruskall Wallis test was used to compare the affected side of TFOA and PFOA groups with the control group. After application of the Bonferroni correction, Mann Whitney-U was used to compare the two-group differences. <h3>Results</h3> The age (p=0.179) and BMI (p=0.150) were similar between the groups. There were no differences on the affected side maximum foot pressure (p=0.603), forefoot weight ratio (p=0.247), rarefoot weight ratio (p=0.240) and total load (p=0.599) between TFOA, PFOA and control groups. FAA was higher in TFOA group [median-IQR: 17.0°(13.3°−35.4°)] when compared to PFOA (p&lt;0.001) and control group (p&lt;0.001). In addition, foot angle axis was lower in PFOA groups [median-IQR: 9.4°(1.5°−19.5°)] than control group [median-IQR: 13.4°(10.0°−15.8°)] (p=0.005). A reference value is appreciable if found to be between 12°−16°. <h3>Conclusions</h3> The angle of the foot plays an important role on optimal weight distribution during walking. Changing the angle of the foot may affect all other joints and create a modifying effect on the moment around the lower extremity. PFOA patients presented lower foot angle axis than normal values while TFOA patients presented higher angles. This may indicate that the intervention should be design for the joint involvement in the knee OA patients. <h3>References</h3> [1] Hinman RS, Crossley KM. Patellofemoral joint osteoarthritis: an important subgroup of knee osteoarthritis. Rheumatology (Oxford)2007;46(7):1057–62. [2] Komaat PR, Bloem JL, Ceulemans RY, Riyazi N,Rosendaal FR, Nelissen RG, Carter WO, Hellio Le Graverand MP, Kloppenburg M. Osteoarthritis of the knee: association between clinical features and MR imaging findings. Radiology2006;239(3):811–7. <h3>Disclosure of Interest</h3> None declared