Aim: Ehlers-Danlos syndromes (EDS) are connective tissue disorders characterized by joint hypermobility, skin hyperextensibility, and tissue fragility. When spondyloarthritis (SpA), an inflammatory arthritis, co-occurs with EDS, overlapping symptoms of joint pain may arise, making diagnosis and management challenging. The aim of this study was to investigate enthesopathic differences in the patellar tendon between patients with EDS and those with co-occurring SpA. Material and methods: Twenty-three participants with EDS and co-occurring SpA (SpA + EDS) and 14 participants with EDS without SpA (EDS-only) underwent ultrasound examination. Assessments were conducted at the inferior patellar pole, mid-patellar tendon, and tibial tuberosity to evaluate enthesopathic changes, including calcifications, enthesophytes, and tendon thickness. Statistical analyses were performed to identify significant differences between groups. Results: The most common tendon pathology was hypoechoic change at the level proximal to the tibial tuberosity and the inferior pole of the patella. Compared with the EDS-only group, tendon thickness at the patellar pole was significantly greater in the SpA + EDS group (p = 0.002). Conclusions: The presence of increased patellar tendon thickness in the SpA + EDS group suggests structural adaptations consistent with enthesopathic change in the context of coexisting inflammatory and connective tissue disorders. These findings highlight the potential role of ultrasound in the evaluation of tendon alterations in hypermobile patients, underscoring the need for longitudinal, multimodal studies to clarify the clinical relevance of these sonographic differences.

spondyloarthritis; hypermobility syndrome; fascia; Ehlers-Danlos syndrome hypermobile type (hEDS); tendinopathy