Efficacy and safety of a 3D-printed arthrodesis prosthesis for reconstruction after resection of the proximal humerus: preliminary outcomes with a minimum 2-year follow-up

Background The purpose of this study was to investigate the feasibility of using a three-dimensional (3D)-printed arthrodesis prosthesis for reconstruction of the proximal humeral defect after tumor resection. Methods A novel proximal humeral prosthesis was designed to restore bone continuity and shoulder arthrodesis and was fabricated via 3D printing technology. Ten patients with primary malignancies in the proximal humerus underwent intra-articular resection and replacement with this prosthesis from 2017 to 2019. Baseline and operative data, oncological and prosthetic survival, and functional status were summarized. Results This cohort consisted of 9 males and 1 female with a mean age of 32.1 +/- 16.1 years. Diagnoses included 5 cases of osteosarcoma, 3 cases of chondrosarcoma and 1 each case of undifferentiated pleomorphic sarcoma and malignant myoepithelioma. The mean operative duration, intraoperative hemorrhage and postoperative length of hospitalization were 151.5 +/- 61.0 min, 410.0 +/- 353.4 ml and 5.3 +/- 1.9 d, respectively. The mean follow-up duration was 29.3 +/- 6.4 months, with a minimum of 24 months for the surviving patients. Two patients experienced local recurrence, and four patients developed distant metastases. Detachment of the taper occurred in two patients. One was managed conservatively, and the other received amputation due to concurrent tumor recurrence. The mean MSTS-93 and ASES scores and ranges of forwards flexion and abduction were 24.9 +/- 3.1, 79.4 +/- 8.3, 71.3 +/- 19.4 degrees, and 61.3 +/- 16.4 degrees, respectively. The functional outcomes were independent of the preservation of the axillary nerve. Histological study of the glenoid component showed evidence of bone ingrowth at the bone-prosthesis porous interface. Conclusion Application of the 3D-printed arthrodesis prosthesis might be a safe and efficacious method for functional reconstruction in patients who underwent resection of the proximal humerus, especially for those without preservation of the axillary nerve.