Background In patients with Psoriatic arthritis (PsA) there are changes in bone remodeling, not well established, that lead to a loss in bone mineral density (BMD) and to bone formation in the form of syndesmophytes and enthesophytes.

The enthesis, one of the most pathological findings that characterize PsA, can be studied with ultrasonography in a more sensitive and specific way than by clinical examination. Enthesopathic structural and inflammatory changes, which can be diagnosed by ultrasonography, are described in the OMERACT consensus and can be quantified by exploration indices such as MASEI.

Objectives To evaluate the association between enthesopathical changes measured by MASEI index and bone remodeling markers in a population of patients with PsA.

Methods Patients diagnosed with peripheral PsA and had been followed in a tertiary hospital, excluding those treated with vitamin D were included. Demographic, clinical, analytical (vitamin D (25OHD), bone turnover markers P1NP and βCTX, BMD (done with a maximum of 24 months before) data was collected.

The entheseal affection count was determined by ultrasonography according to the MASEI index, which was re stratified in inflammation index and structure index, and by anatomical areas. Statistical study was done with the SPSS 17.0 program.

Results 66 patients were included, 62.1% (41) were women, with a mean age of 56.8±11.9 years and mean duration of disease of 108.1 ±102.5 months; 84.8% (56) were treated with methotrexate and 33.3% (22) were receiving biological therapy (anti-TNF). Mean MASEI index was 13±9.7; mean structure index was of 9.3±5.9; and mean inflammation index 3.7±4.5. The quadricipital and achilles enthesis had higher mean MASEI indexes (4.2±3.4 and 2.9±2.1, respectively). MASEI and the structure index were positively associated with age (r=0.31,p<0.05 and r=0.42, p<0.01, respectively); contrary to the inflammation index.

Patients with osteoporosis had a mean age significantly greater than the rest of the sample.

No association was found between the results of BMD (stratified as normal, osteopenia and/or osteoporosis) and total MASEI index, structure score, inflammation score or each of the anatomical areas that were studied. As to bone turnover markers, P1NP and βCTX showed a tendency to an inverse relation with age. βCTX was inversely related to MASEI index of quadriceps and achilles (p<0.05). Likewise, when excluding patients treated with antiresorptive and anabolic agents the tendency maintains the same but is not statistically significant (p=0,078 and 0,076, respectively).No other associations were found between these bone remodeling markers and the rest of ultrasound indexes of enthesis.

Conclusions Structural changes seen in the enthesis of our group of patients with PsA associate with a reduction of the bone turnover marker βCTX.

Disclosure of Interest None declared