Aims: Tumour defects of the proximal humerus can be reconstructed using hemiarthroplasty, reverse shoulder arthroplasty (RSA), or anatomical total shoulder arthroplasty (TSA). This study aimed to evaluate clinical and functional outcomes of reconstructions of proximal humeral tumour defects with MUTARS endoprostheses.Methods: A total of 165 reconstructions were included: 98 (59%) hemiarthroplasties, 61 (37%) RSAs, and six (4%) TSAs. Median age was 54 years (IQR 31 to 68). Median follow-up time was 5.9 years (IQR 2.83 to 10.50). Competing risks models were employed to estimate the cumulative incidence of revision (CIR) for mechanical reasons and infection with local recurrence and mortality as competing events. The range of motion was reported using descriptive statistics.Results: Axillary nerve preservation and deltoid muscle reattachment were observed in 89% and 96% of cases, respectively, without significant differences between implant types. Rotator cuff refixation was less frequent in RSA (78%) compared to hemiarthroplasty (91%). Overall, 26 implants (16%) were revised for mechanical complications (dislocation n = 11, loosening n = 2, periprosthetic fracture n = 3) and infection (n = 10). Patients with previous surgery at the same site had a higher revision risk due to instability (cause-specific hazard ratio 3.7; 95% CI 1.3 to 10.8). The CIRs for mechanical reasons (Henderson 1 to 3) in the entire population at two, five, and ten years were 7% (95% CI 3 to 11), 11% (95% CI 6 to 17), and 13% (95% CI 7 to 20), respectively. For periprosthetic joint infection (Henderson 4), the CIRs were 5% (95% CI 2 to 10), 7% (95% CI 3 to 12), and 7% (95% CI 3 to 12). Compared with hemiarthroplasty, RSA offered superior median anteflexion (73° (IQR 40 to 90) vs 30° (IQR 5 to 45)), abduction (70° (IQR 38 to 90) vs 30° (IQR 5 to 45)), and external rotation (15° (IQR 0 to 28) vs 5° (0 to 19)).Conclusion: MUTARS proximal humerus reconstruction outcomes are satisfying, particularly in terms of mechanical failure. RSA and hemiarthroplasty exhibit comparable revision risks, with previous surgery at same site as a prognostic factor for revision due to dislocation. RSA appears to provide the best functional outcome.Cite this article: Bone Jt Open 2025;6(6):715–723.

Background: Joint-sparing resection of juxta-articular knee tumors is challenging. With the development of 3D printing technology, custom-made cutting guides were introduced with the aim to improve the accuracy of tumor resection margins and to shape the allograft for adequate matching in biological reconstruction. Materials and Methods: Between December 2017 and July 2023, 13 patients underwent joint-sparing juxta-articular resection of the knee for a primary bone tumor at our institution. Resection was performed using a custom-made 3D-printed titanium alloy cutting guide and reconstruction was performed using a custom-shaped allograft. The mean follow up was 50 months (min 14–max 81). The study of cutting accuracy was performed by digital examination of CT images of the resection specimen in eight patients. Results: The average cutting error was 2.3 mm. Surgical margins were wide in all patients. Four patients developed postoperative complications that led to the removal of the allograft in one case. The average functional result according to the Musculoskeletal Tumor Society Score was 26 (min 14–max 30), and according to the Oxford Knee Score it was 44 (min 22–max 48). Conclusions: Custom-made titanium cutting guides resulted effective in improving the accuracy of joint-sparing juxta-articular resection of the knee and allograft matching.

Background: Restoration of shoulder function after resection for primary bone tumors of the scapula is a challenge, according to the sacrifice of rotator cuff muscles and glenoid. This study aims to define the advantages of a prosthetic design over the others in different clinical situations, comparing the functional outcomes and complication rate of patients treated for a primary tumor of the scapula or surrounding soft tissue with resection and reconstruction with custom-made prostheses. Materials and methods: Eight patients were retrospectively reviewed; seven underwent total scapulectomy, while one underwent partial. A humeral prosthesis was placed in five patients (four with constrained and one with anatomical design), and in one patient, a transposition of the latissimus dorsi was performed, in order to replace the deltoid muscle. Results: At a median follow-up of 55 months (24–97), two complications requiring further surgeries (a local recurrence and a wound dehiscence) were assessed in two patients, all managed without scapular prosthesis removal. The median MSTS score was 24 (14–30); in the group of constrained prosthesis, the median MSTS score was 24 (19–26), while in the group of nonconstrained prosthesis it was 19 (14–26). The patient with partial scapular reconstruction scored 30 points. Conclusions: After resection of the scapula, custom-made prostheses represent an effective reconstruction, with good functional results and low complication rate. In patients in whom the rotator cuff and its innervation are preserved, an anatomic design seems to allow for good functional results; after rotator cuff sacrifice, a constrained prosthetic design in our experience seems to allow for a stable and painless shoulder with acceptable functional results. Level of evidence: IV.