Reverse shoulder megaprosthesis replacement for aggressive aneurysm bone cyst of proximal humerus: Case report and literature review

Abstract

Introduction and Importance: Wide resection in the surgical treatment of aneurysms bone cysts is often performed in cases where the tumor is large, recurrent, growing, and intensely invasive. Reshaping the defect after tumor removal is a necessary issue to restore shape and maintain function for the patient.

Case Presentation: A 26-year-old male patient, diagnosed with an aneurysm bone cyst in the proximal humerus, underwent surgery for curettage and bone grafting twice. After surgery, there was still pain in the shoulder area, the tumor progressed aggressively with limited shoulder movement. Based on the imaging re-evaluation, it was shown that the tumor increased rapidly in size, invaded the soft tissue, and completely changed the normal structure of the shoulder joint, and the proximal humerus. We used a reverse shoulder joint with an additional module to restore the bone defect of the tumor and the function of the shoulder joint. Follow-up showed that the patient no longer experienced pain in the shoulder area, and shoulder joint function recovery is progressing well, with a Musculoskeletal Tumor Society (MSTS) score of 25 & 28, and shoulder joint function score according to ASES scale: 80 & 93.33 respectively at 3 months and 6 months after surgery.

Clinical Discussion: Aggressive aneurysm bone cyst of proximal humerus is not common and still a challenge to the treatment. Due to the bone and joint destruction, the indication of tumor resection and reconstruct the joint and bone loss is required. Among several solutions, reverse shoulder megaprosthesis is the newest one that can favor the purpose of our treatment. Up to now, this solution is mainly used to preserve malignant bone tumors.

Conclusions: Tumor wide resection with modular reverse shoulder replacement with the modular segment is a reasonable intervention option in cases of large aneurysm bone cysts, with rapid recurrence, aggressive progression, and soft tissue invasion.