POS0126 EARLY STAGE HAND OSTEOARTHRITIS IN PATIENTS WITH THE EHLERS-DANLOS SYNDROME: AN EXPLORATIVE STUDY
Authors: L. Rombaut, K. De Baere, E. Debacker, L. Decavele, F. Malfait, R. Wittoek
Journal: Annals of the Rheumatic Diseases (2021)

Background: The Ehlers-Danlos Syndromes (EDS) are a group of rare heritable connective tissue disorders caused by various defects in the biosynthesis or secretion of fibrillar collagens. The three main clinical features of EDS are joint hypermobility, skin fragility and general soft tissue fragility. 13 clinical subtypes of EDS are recognized, of which the hypermobile type (hEDS) and classical type (cEDS) are the most prevalent. It has been hypothesized that the (micro-)trauma in the joint due to typical subluxations and dislocations, make EDS patients prone to developing osteoarthritis (OA) in early stage. Conversely, it has been mentioned that joint hypermobility provides a larger joint surface area and prevents OA. Abnormal biomechanical loading has been identified as a risk factor for the development of OA in the wrist and hand. However, no studies have yet been performed in EDS patients. Objectives: The primary aim was to investigate the presence of any degenerative features for hand OA, and if this differs between cEDS and hEDS patients. The second aim was to evaluate hand function and pain related to OA signs in EDS patients. Methods: cEDS and hEDS patients between 35 and 50 years old were invited to participate. cEDS diagnosis was genetically confirmed and hEDS diagnosis was performed according the clinical 2017 hEDS criteria. Exclusion criteria were a body mass index ≥35, not being able to stand straight up for five minutes, suffering from an auto-immune disease or rheumatological condition, or pregnancy. Conventional X-rays of both hands were performed and scored independently by three assessors according to Kallman 1 . Presence of osteophytes (0-3), joint space narrowing (0-3), malalignment (&gt;15°)(0/1), erosions (0/1), subchondral sclerosis (0/1), and subchondral cysts (0/1) were scored in all interphalangeal (distal and proximal), metacarpophalangeal and thumb base joints of both hands 1 . We defined early hand OA as minimally three features (≥1) were present. Several clinical assessments were made, e.g. tenderness, bony swelling and soft tissue swelling. The Michigan Hand Outcomes Questionnaire (MHOQ) and Australian/Canadian Osteoarthritis Hand Index (AUSCAN) questionnaires were completed. Results: In total, 31 patients (mean age 41 ± 5.6 years, 13 men and 18 women) diagnosed with EDS participated, of whom 19 with cEDS and with 12 hEDS. In total, 927 joints were assessed. Level of agreement of radiographic assessments was very high (&gt;98%). Early hand OA was found in more than 40% of the EDS patients, with a significant higher frequency in cEDS patients compared to hEDS patients (58% vs. 17%) (p=0.032). Joint space narrowing was most frequently present and significantly more in the cEDS patients compared to hEDS patients (79% vs. 21%) (p=0.003). However, radiographic changes were found in only 10% of all finger joints. Of all fingers, thumb joints were most affected. Regarding the clinical features of hand OA, all patients showed deformity in one or more finger joints, most frequently at the thumb, especially the IP joint (both hyperflexion and hyperextension). Tenderness and bony swelling was present in 36% and 45% of all patients, respectively, whereas soft tissue swelling was less frequently observed (10% of all patients). Here, no significant differences were found between cEDS and hEDS patients. Moderate disability was present (mean (SD) AUSCAN= 45.47 (27.10) and MHQ = 65.97 (14.21). cEDS showed significant less hand pain (p=0.03), a better hand function (p=0.03) and less disability (p=0.026) than hEDS. Conclusion: This explorative study demonstrates that a high number of EDS patients present with minimal degenerative features of hand OA, but in a minority of joints. Patients with cEDS were significantly more affected, but showed a better function compared to hEDS. Possibly, cEDS patients are more susceptible to develop hand OA. References: [1]Altman R, Gold G. Atlas of individual radiographic features in osteoarthritis, revised. OARSI. 2007;15:A1-A56. Disclosure of Interests: None declared