The survival, mechanisms of failure, and function after total humeral replacement in patients with primary sarcomas.

Background: Total humeral replacement (THR) is one of the few options for reconstruction when the humerus is extensively involved or with skip lesions. However, there are few studies focusing on the long-term outcomes of THR for primary sarcomas, and the function and endoprosthesis survival remains uncertain.

Questions/purposes: The purposes of this study were to answer the following questions: (1) What are the oncological and functional outcomes of THR? (2) What are the overall survival (OS) and revision-free survival rates of THR? (3) What are the failure mechanisms of THR?

Methods: A retrospective cohort study was conducted on 34 patients (22 males, 12 females) between January 1997 and December 2021. The average age was 30.1 ± 20.1 years (7-72) and the pathological type included osteosarcoma (24), chondrosarcoma (6), Ewing's sarcoma (2), and undifferentiated pleomorphic sarcoma (2). The oncological outcomes included local recurrence, metastasis, and OS. The functional outcomes were assessed by the Musculoskeletal Tumor Society Score-93 (MSTS), the Toronto Extremity Salvage Score, the American Shoulder and Elbow Surgeons score, and the range of motion of the shoulder. All modes of failure were recorded in the follow-up. The significance level was adjusted to 0.025 after Bonferroni correction.

Results: The mean follow-up of all patients was 78.5 ± 72.6 months (range, 9-292 months) and 103 ± 71.6 months (range, 32-292 months) in all survivors. Fourteen patients (41.7%) died in the last follow-up. The 5-, 10-, and 15-year OS rate of the endoprosthesis was 94% (95% confidence interval 66.6%-99.1%). The average Musculoskeletal Tumor Society Score-93 score was 78% (range, 53%-86%), the average Toronto Extremity Salvage Score was 80% (60%-90%), and the average American Shoulder and Elbow Surgeons was 79% (63%-93%), respectively. The most common failure mechanisms were tumor progression (type 5, 17.6%, 6/34), followed by soft tissue failure (type 1, 14.7%, 5/34), and structural failure (type 3, 2.9%, 1/34).

Conclusions: THR is a long-term reconstructive option for patients with massive tumors requiring complete resection of the humerus. The most common failure mechanisms were tumor progression (type 5) and soft tissue failure (type 1). Overall functional outcomes were acceptable with good hand and elbow function, but shoulder function was limited.