Unicameral Bone Cyst: A Retrospective Study of Three Surgical Treatments

Abstract

Between 1979 and 2004, 167 patients younger than 20 years were treated surgically for humeral or femoral unicameral bone cysts with either injection of corticosteroids (steroids), curettage plus bone grafting (curettage), or a combination injection of steroids, demineralized bone matrix, and bone marrow aspirate (SDB) at Children's Hospital of Boston and Massachusetts General Hospital (mean followup, 7.3 years; range, 1 month-27 years). Outcomes included treatment failure (defined clinically as subsequent pathologic fracture or need for retreatment to prevent pathologic fracture) and complications. Information was obtained from medical records and by telephone questionnaire. After one treatment, 84% of cysts treated with steroids experienced failed treatment versus 64% with curettage and 50% with SDB. For unicameral bone cysts requiring retreatment (regardless of first treatment), 76% retreated with steroids had failed treatment versus 63% with curettage and 71% with SDB. Curettage was associated with the lowest rate of posttreatment pathologic fractures and highest rate of pain and other complications. Multivariate logistic regression indicated treatment with steroids alone and younger age were independent predictors of failure. We believe SDB is a reasonable first treatment for unicameral bone cysts in the humerus and femur in patients younger than 20 years, being less invasive yet comparable to curettage in preventing recurrence.

Injection of Demineralized Bone Matrix With Bone Marrow Concentrate Improves Healing in Unicameral Bone Cyst

“…These data are difficult to compare with data presented in the literature due to differences in the method of evaluation and type and number of bone marrow or steroid injection. However, most reports that specifically refer to the healing rate after the first treatment with bone marrow injection show lower percentages than achieved in our series [5,6,35,[41][42][43]. On the other hand, the percentage of healing rate following the first treatment with steroid injection in our series is lower than most of other reports [5,6,11,34,41].…”

“…Of these patients, 35 were not surgically treated, five were treated with open surgery, and six were lost to followup shortly after treatment. Of the remaining 184 patients, 143 were treated with repeated injections of methylprednisolone (Steroids Group) and 41 with a single injection of DBM associated with autologous BMC (DBM + BMC Group).…”

“…Fracture of the cyst is one cause of failure after the first treatment; Neer et al [27] reported up to 80% of fractures in patients followed without surgical treatment. In patients surgically treated, fracture has been reported in 2.6% of cases treated with curettage and bone grafting [35]; from 7.7% [4] to 28% [41] and 33% [42] in patients treated with marrow or steroid injection. We observed no difference in the number of fractures that occurred in our series in the two groups (12% in the DBM + BMC Group versus 17% in the Steroid Group), resulting in the average of fractures reported in series dealing with patients treated with either steroid or bone marrow injection.…”

“…Although the bone grafts potentially promote new bone formation inside the cyst, the rate of recurrence is 5% to 50% by 1 to 8 years. Further, donor site morbidity has reduced the appeal of this procedure for some surgeons [11,26,35]. Thus, there was a need for less invasive treatments considering the benign and self-limited nature of the lesion.…”

“…However, subsequent studies reported a lower healing rate for this procedure with only 41% to 63% healing after the first injection [6,13]. Sung and colleagues reported a failure rate of 84% after the initial treatment with steroids and 76% after the second procedure [35]. The injection of bone marrow (BM) alone [5,6,9,21,42,43] or in combination with demineralized bone matrix (DBM) [17,18,29,30,35] has also been proposed as an alternative to steroids for treating UBC.…”