Background Enthesopathy is the pathologic alteration of bony insertions of tendons, ligaments or joint capsules.¹ Enthesopathy is hallmark of spondyloarthropathies and has been reported in various disorders, like Behçet’s disease. Enthesopathy most commonly observed in lower extremities and manifests itself as localized pain. Heel and calf pain is common in patients with Familial Mediterranean fever (FMF)², and we hypothesize that this could also be due to the enthesopathy.

Objectives To investigate a possible association between FMF and enthesopathy.

Methods Fifty-six patients with FMF and 11 patients with FMF associated spondyloarthropathy (FMFS) were enrolled. Forty-seven healthy individuals and 36 patients with AS formed the healthy and diseased control groups. Musculoskeletal complaints were meticulously questioned and all patients underwent a detailed physical and ultrasonographic (US) examination. US evaluation was performed from five regions; superiorpole of the patella at the insertion of the quadriceps tendon, the inferior pole of the patella at the proximal insertion of the patellar tendon, the tibial tuberosity at the distal insertion of the patellar tendon, the superior pole of the calcaneus at the insertion of the Achilles tendon, and the inferior pole of the calcaneus at the insertion of the plantar fascia. US scoring was made according to the GlasgowUltrasound Enthesitis Scoring System (GUESS) for each individual.³ Demographic data, disease characteristics, MEFV genotypes and HLA B27 results were retrieved from the medical records.

Results Lower extremity pain and swelling and physical examination findings consistent with enthesopathy were frequent in all patient groups with the highest prevalence in FMFS group. Achilles and plantar regions were the most common sites for patient reported pain as well as physical examination finding consistent with enthesopathy and US-detected entheseal abnormality in all patient groups. FMF patients harboring M694V variant had higher GUESS scores compared to patients with other variants (2.78±2.43 vs. 1.37±1.67, p=0.026). There was no statistically significant difference in mean±SD GUESS scores between healthy subjects and those FMF patients with genetic variants other than M694V (1.38±1.42 vs 1.37±1.67, p>0.05).

Conclusions Enthesopathy in FMF patients might be associated with the presence of M694V mutation and may not be a feature of general FMF population. Our results further support the previous evidence regarding an association between M694V and spondyloarthropathy.

1. Benjamin M, et al. Where tendons and ligaments meet bone: attachment sites (“entheses”) in relation to exercise and/or mechanical load. J Anat 2006;208:471-90.

2. Benjamin M, et al. The enthesis organ concept and its relevance to the spondyloarthropathies. Adv Exp Med Biol 2009;649:57-70.

3. Balint PV, et al. Ultrasonography of entheseal insertions in the lower limb in spondyloarthropathy. Annals of the rheumatic diseases 2002;61:905-10

Disclosure of Interest None Declared