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Osteoblastoma of the Sacrum: Report of 18 Cases and Analysis of the Literature

Ruggieri, Pietro MD, PhD*; Huch, Klaus MD; Mavrogenis, Andreas F. MD, PhD*; Merlino, Biagio MD; Angelini, Andrea MD*

doi: 10.1097/BRS.0000000000000061
Clinical Case Series

Study Design. Retrospective case series.

Objective. (1) To analyze clinical and radiographical characteristics, treatment, and outcome in patients with sacral osteoblastoma, (2) to evaluate progression-free survival and local recurrence rate, and (3) to identify prognostic factors.

Summary of Background Data. Osteoblastoma is a rare tumor that has been reported to affect the sacrum from 7% to 17%. Symptoms are various and the diagnosis is often delayed.

Methods. From 1980 to 2010, 18 patients with sacral osteoblastoma (16 males and 2 females) were treated at Rizzoli Institute. Lesion involved S1 (2 cases), S1–S2 (3 cases), S2 (1 case), S2–S3 (1 case), S2–S4 (1 case), S3 (2 cases), S3–S4 (5 cases), S4 (1 case), and almost the entire sacrum in 2 cases. According to Enneking classification for benign bone tumors, 13 (72%) were diagnosed at stage 2 and 5 (28%) at stage 3. Mean tumor volume was 64 cm3 (range, 2–441 cm3). Nine patients had preoperative magnetic resonance imaging. Five patients had a previous inadequate intralesional surgery elsewhere. Treatment consisted in intralesional surgery (16 cases), intralesional surgery and radiotherapy (1 case), and wide resection (1 case). Local adjuvants used were phenol (7 patients), cryocoagulation with “iceball” technique (1 case). Embolizations were performed in 7 patients.

Results. At a mean of 8.4 years (range, 1–28 yr), 15 patients (83%) remained continuously disease free, whereas 3 patients had local recurrence (17%). Progression-free survival was 87% at 5 years and 74% at 10 years. No statistical difference was found between patients who received or not local adjuvants (P = 1.254), older or younger than 20 years (P = 0.970), at stage 2 or 3 (P = 0.826), evaluated preoperatively with or without magnetic resonance imaging (P = 0.160), primarily treated versus patients with previous intralesional surgery elsewhere (P = 0.131).

Conclusion. In our series, curettage was successful in most of the patients. Local adjuvants did not seem to reduce the risk of local recurrence when combined with intralesional surgery.

Level of Evidence: 4

We present a series of 18 sacral osteoblastomas followed at long term. All patients were disease free at last follow-up, and the progression-free survival rate was 87% at 5 years. Curettage was successful in most of the patients. Local adjuvants, age, stage, preoperative magnetic resonance imaging, and previous surgery did not affect survival.

*Department of Orthopedics, University of Bologna, Istituto Ortopedico Rizzoli, Bologna, Italy

Department of Orthopaedic Surgery, University of Ulm, Ulm, Germany; and

Department of Radiology, Catholic University, Rome, Italy.

Address correspondence and reprint requests to Pietro Ruggieri, MD, PhD, Department of Orthopedics, University of Bologna, Istituto Ortopedico Rizzoli, Via Pupilli, 1-40136 Bologna, Italy; E-mail:

Acknowledgment date: April 11, 2013. First revision date: July 5, 2013. Second revision date: September 25, 2013. Acceptance date: September 25, 2013.

The manuscript submitted does not contain information about medical device(s)/drug(s).

No funds were received in support of this work.

No relevant financial activities outside the submitted work.

© 2014 by Lippincott Williams & Wilkins