Osteonecrosis in systemic lupus erythematosus.

OBJECTIVES

To define the proportion of osteonecrosis (ON) in our patient population with lupus and to identify factors associated with the development of ON in systemic lupus erythematosus, as well as to carry out a descriptive analysis of ON cases.

MATERIALS AND METHODS

Observational retrospective study of 158 patients with SLE (ACR 1982 criteria). Demographic and laboratory data, clinical manifestations, SLICC, SLEDAI, cytotoxic and steroid treatments were compared. In patients with ON, we analyzed time of disease progression and age at ON diagnosis, form of presentation, joints involved, diagnostic methods, Ficat-Arlet classification, and treatment. To compare the means, t-test or Mann-Whitney's test were employed and the cHi-2 test or Fisher's exact test, as appropriate, were used to measure the equality of proportions.

RESULTS

ON was present in 15 out 158 patients (9.5%), 13 women and 2 men, with a mean age of 30 (r: 16-66) at diagnosis and 35 months of evolution until diagnosis (r: 1-195). Among the 15 patients, 34 joints presented ON, 23 were symptomatic and 22 were diagnosed by magnetic resonance images. Twenty-six occurred in hips (24 bilateral), 4 in knees and 4 in shoulders. In 13 patients, ON involved 2 or more joints. At onset, 28 joints were in stage i-ii, one in stage iii and 5 had no data and; in the end, 14 were in stage iii-iv, 5 in stage i-ii and 15 had no data. Twenty-nine underwent conservative treatment with rest and 8 hips required joint replacement. ON progression was associated with Cushing's syndrome (P=0.014) OR 4.16 (95% CI 1.4-12.6) and 2nd year SLICC (P=0.042). No relation with clinical manifestations, lab results, cytotoxic treatment, steroid treatment (total accumulated dose, mean daily dose and duration) metilprednisolone pulses, nor activity was found. All patients with ON received antimalarials, in contrast to 77% of those without ON.

CONCLUSIONS

The proportion of ON was 9.5%, mainly in women, 76% in hips (26) and 92% bilaterally. They were associated significantly with Cushing's syndrome and accumulated damage at second year.