Treatment outcomes of the simple bone cyst: A comparative study of 2 surgical techniques using artificial bone substitutes

Simple bone cysts (SBCs) are benign lesions of unknown etiology. Because of its high relapse rate, they occasionally need a long period of treatment and restriction of activities in children and adolescent. Although various treatment modalities with variable differing outcomes have been described in the literature, no consensus has been reached regarding the standard treatment. The purpose of this study was to evaluate the outcome of a minimally invasive technique that uses a ceramic hydroxyapatite cannulated pin (HA pin) for the treatment of SBCs. Between 1998 and 2015, we have treated 75 patients with SBCs either with continuous decompression by inserting HA pins after curettage and multiple drilling (group 1, n = 39 patients) or with calcium phosphate cement (CPC) filling after curettage (group 2, n = 36 patients). These patients were retrospectively analyzed for recurrence-free survival (RFS) and factors implicated in SBC recurrence. Seventy-five patients (50 man and 25 females) with a mean age of 17.5 ± 11.6 years and a histopathologically confirmed diagnosis of SBCs were included. The mean follow-up period was 33 ± 25.3 months. RFS were 88% at 1 year and 81% at 5 years. Residual or progressing cysts were observed in 12 patients after the surgery and 10 of them underwent additional surgery. Recurrence rate was significantly higher in patients under the age of 10 years (P = .01), in long bone cysts (P = .01), and in active phase cysts (P = .003) (log-rank test). Multivariate analysis results revealed that age less than 10 years was an independent risk factor of recurrence (P = .04). No significant difference in recurrence rate was observed between groups 1 and 2. However, the mean operating time was significantly shorter in group 1. (62.4 ± 25.6 vs 110.5 ± 48.4 minutes in group 2). Continuous decompression using HA pin is a less invasive surgical technique for the treatment of SBCs compared with CPC filling and has a high healing rate. The relapse rate was still high when the cysts were caused in children aged less than 10 years, located in the long bone, or remained adjacent to the epiphysis. Level of Evidence: Level 3, Retrospective comparative study