A Novel Minimally Invasive Technique for Treatment of Unicameral Bone Cysts.

Management of unicameral bone cysts (UBC) remain controversial. These cysts seldom heal spontaneously or even after pathological fracture. Sometimes these cysts can be very large and incredibly troublesome to the patient. Various treatments exist with variable success rates. We present our experience of treating these lesions by continuous drainage. Over a seven year period, six patients with unicameral bone cysts were treated by inserting a modified drain into the wall of the cyst. The aim of surgery was to place the drain in a dependent area of the cyst, through the cortex allowing for continuous drainage. This was achieved through a small incision under radiographic control. A cement restrictor (usually used for femoral canal plugging during total hip replacements) was modified and inserted to prevent closure of the drain site. A redivac drain was passed through the plug into the cyst. The drain was left in place for a week to establish an epithelialized pathway which hopefully would remain patent, into the subcutaneous tissues, after the drain had been removed. There were four males and two females in the group and the age range was 6 -12 years. Four of the lesions were in the upper humerus, one in the proximal femur and the other one in the proximal tibia. Healing was rated according to the modified Neer classification. Grade 1 (healed) and Grade 2 (healed with defect) was defined as excellent outcome. Persistent /Recurrent cysts (Grade 3 and 4) were noted as unsatisfactory. Five cases were completely healed. Only one had a further fracture and there were no recurrent fractures. All the patients reported complete comfort and they all were able to re-engage in recreational activities without restriction. We think that reducing the intra-medullary pressure in these lesions will lead to healing. We report a safe and minimally invasive technique for the management of UBC.