Surgical treatment for symptomatic non-ossifying fibromas of the lower extremity with calcium sulfate grafts in skeletally immature patients

Non-ossifying fibromas (NOFs) are common benign bone lesions found in children and adolescents. They usually involve metaphysis of long bones, tend to gradually disappear with age and usually do not require surgery, while they are not associated with pathological fractures. The aim of this study was to evaluate the outcome and efficacy of a single-stage procedure, comprising curettage of the lesion and calcium sulfate pellet (CaSP) grafting, in skeletally immature patients with large, symptomatic NOF of the lower extremity, and the possible limitations of the procedure.

Nine skeletally immature patients with symptomatic NOF of the lower extremity were treated between 2013 and 2016. Details of age, history of presentation, location and size (in mm) of the lesion, histology and follow-up details were recorded. Lesions were classified in Ritschl radio-morphological stages. CaSP integration was assessed by Irwing’s classification. The average size of lesions was 54.6 mm in length (range 31–95). All lesions were symptomatic. The average bone expansion in relation to the bone diameter was 67.4% in the transversal plane (range 31–100) and 77.8% in the sagittal plane (range 55–100). Mean patient age at time of treatment was 9.8 years (range 7–14); mean follow-up was 2 years (range 2–4). All the patients were symptomatic, and 8 out of 9 (89%) NOFs were Ritschl type B. All the patients were treated surgically with a single-step approach, as described.

On average, 86 mL of CaSPs was used per case (range 10–250). None of the patients required internal fixation. At last follow-up visit, CaSPs were fully incorporated in all the patients according to Irwing’s classification (Stage 3). No serous drainage from wounds was recorded in any of the patients. No cases of pathological fracture, bone deformity, growth arrest or growth disturbance or infection were observed. At last follow-up visit, all the patients had resumed full sport and daily life activities.

CaSPs offer a safe, cheap, convenient alternative to the autograft as an implant substitute that helps regeneration of bone in the defects produced by curettage of large, symptomatic NOFs. Chemical cauterization of bone walls does not interfere with CaSP integration into bone tissue.