Predictive characteristic of simple bone cyst treated with curettage and bone grafting

BACKGROUND The efficiency of treating simple bone cyst (SBC) is low. Depending on the choice of treatment, a positive response occurs in 20 to 80 % of cases. These rates are unacceptable, particularly considering they concern the treatment of benign lesions affecting children. Although cyst curettage is one of the first known ways of treating SBC, no precise qualification criteria exists for this procedure. The aim of our study is to identify which type of cyst may be most effectively treated using curettage with grafting. METHODS A retrospective analysis was performed on 24 patients referred to our clinic for SBC treatment. To identify predictive factors, the group of patients who positively responded to treatment (Neer stages I and II, n = 14) were compared with the group in which recurrences occurred (Neer stages III and IV, n = 10). RESULTS Significantly fewer patients with lesions located in the humerus (chi(2) = 9.351; p < 0.05) and without pathological facture at the time of diagnosis (p = 0.017) were found in the group with no recurrence. The following radiological parameters were found to vary significantly between groups: cyst area (z = 3.121; p < 0.01), cyst index (z = 2.213; p < 0.05) and cyst diameter ratio (z = 2.202; p < 0.05). In the group with no recurrences, the mean values of these parameters were found to be lower than in group with poor response to treatment. No statistically significant differences regarding age, sex or type of bone graft (p > 0.05) were found. Recurrences were experienced by 10 patients (41.7 %) during the 3-year period after surgery CONCLUSION In the group treated with curettage, associations were identified between worse treatment results and the location in the humerus, pathological fractures at the time of diagnosis, large cyst area, large cyst index and large cyst diameter.