Background The impairment of function in patients with rheumatoid arthritis (RA) is determined by several factors related to the disease including joint damage. The foot, a location frequently affected during course of the disease, has a major impact on the lower limb and could cause functional disability.
Objectives The purpose of this study is to evaluate the impact of the rheumatoid foot on function of patients with RA.
Methods Cross-sectional study was conducted in 33 patients with RA. Patients with static lower limb disorder or foot injury from other origin were excluded. Demographic and clinical characteristics were collected: age, sex, BMI, disease duration, tender joint count, swollen joint count, foot pain evaluated on an VAS, foot squeeze test and various podiatric abnormalities observed clinically (forefoot, midfoot and rearfoot). Biological characteristics also collected: sedimentation rate in the first hour, C reactive protein, rheumatoid factor and anti-CCP. Disease activity was evaluated by DAS28, CDAI, SDAI and DAS44. Functional repercussions were estimated by the French Functional Index (FFI), comprising 23 items, divided into 3 sections: pain, function and limitation of activity. Functional disability was studied by the Leeds Foot Impact Scale (LFIS), which includes 51 items (21 items specific to foot function alteration (LFIS-I) and 30 related to foot disability (LFIS-D)). Statistical analysis was performed using SPSS21 software.
Results Thirty-three patients followed for RA were included. The mean age of our patients was 49.39±10.52 with a female predominance (87.9%). Mean disease duration was 9.96±7.49 years. In all patients; 21 (95.5%) were seropositive. The mean DAS28 was 5.53±1.38 and the mean HAQ was 1.37±0.83. 93.9% of our patients had bilateral foot pain; 69.7% in the forefoot, 18.2% in the midfoot and 42.4% in the hindfoot. The medial retromalleolar tumefaction was found in 21.2% of the patients and the lateral retromalleolar tumefaction in 45.5% of them. The squeeze test was positive in 23 (69.7%) patients. Prevalences of Podiatric abnormalities were noted in the following ordre: hallux valgus (48.5%), quintus varus (12.1%), hallux rigidus (6.1%), claw toe (15.2%), triangular forefoot (9.1%), rearfoot valgus (27.3%) and rearfoot varus (27.3%).
Mean FFI was 52.35±25.63 (FFI-pain: 58.69±24.41, FFI-function: 53.66±30.48 and FFI- limitation of activity: 39.33±30.58). Mean LFIS-I was 11.48±5.36 and mean LFIS-D was 19.96.
A high FFI was associated with foot pain (p=0.034); in midfoot (p=0.029) and rearfoot (p=0.005) and with high disease activity: DAS28 (P=0.005), CDAI, SDAI and DAS44 (p=0.0001).
LFIS-I and LFIS-D were statistically related to pain in foot (p=0.019) (midfoot (0.042), hindfoot (0.003)), and to a positive squeeze test. The disease activity was positively correlated with high LFIS-I and LFIS-D (p=0.0001). The presence of medial retro-malleolar swelling, posterior gutter filling and calcaneal varus is responsible for a high FFI, LFIS-I and LFIS-D with respectively: p=0.0001, p=0.003, p=0.003.
Conclusions The rheumatoid foot alters function. It causes disability which is related to foot pain, rearfoot podiatric abnormalities and disease activity.
Disclosure of Interest None declared