The Modified Harrington Procedure for Metastatic Peri-Acetabular Bone Lesion Using a Novel Highly Porous Titanium Revision Shell with Long Lever Arm Screw.

Background and Objectives: Peri-acetabular metastases often lead to significant pain and functional impairment. Surgical interventions, including the Harrington procedure, aim to address these challenges. This study evaluates a modified Harrington procedure using the MUTARS® PRS® (Pelvic Revision Shell) with an 8 mm fixation screw for severe acetabular defects resulting from metastatic lesions. Materials and Methods: Retrospective analysis of 12 patients treated between January 2020 and December 2023 was conducted. The procedure involved using the novel MUTARS® PRS® with an 8 mm in diameter dome screw (length 70-100 mm). Outcome measures included implant positioning changes, complication rates, functional outcomes, implant longevity, and patient survival. Radiological assessments were performed postoperatively, with follow-ups at 3, 6, 12 months, and annually thereafter. Results: Average follow-up was 15 ± 11 months, with 67% patient survival at 1 year and 44% at 2 years. Implant survivorship remained 100%. Harris Hip Score improved significantly from 37 ± 22 preoperatively to 75 ± 15 at the last follow-up. No revisions involving implant components were reported. Complications occurred in 5 of 12 patients. Overall, PRS® demonstrates effective osseous ingrowth, high primary stability, immediate full weight-bearing, and low complication rates. Conclusions: PRS® integrates facilitating osseous ingrowth for preferable long-term outcomes, while efficiently transmitting the weight-bearing load to the intact aspect of the pelvis using a long 8 mm lever screw, enhancing the primary stability of the construct. It proves to be an effective and reproducible technique for managing destructive metastatic lesions of the acetabulum and peri-acetabular region, even in irradiated bone.

Modular tumor prostheses: are current stem designs suitable for distal femoral reconstruction? A biomechanical implant stability analysis in Sawbones.

INTRODUCTION: High loosening rates after distal femoral replacement may be due to implant design not adapted to specific anatomic and biomechanical conditions. MATERIALS AND METHODS: A modular tumor system (MUTARS®, Implantcast GmbH) was implanted with either a curved hexagonal or a straight tapered stems in eight Sawbones® in two consecutively generated bone defect (10 cm and 20 cm proximal to knee joint level). Implant-bone-interface micromotions were measured to analyze main fixation areas and to characterize the fixation pattern. RESULTS: Although areas of highest relative micromotions were measured distally in all groups, areas and lengths of main fixation differed with respect to stem design and bone defect size. Regardless of these changes, overall micromotions could only be reduced with extending bone defects in case of tapered stems. CONCLUSIONS: The tapered design may be favorable in larger defects whereas the hexagonal may be advantageous in defects located more distally.

Silver-coated endoprosthetic replacement of the proximal humerus in case of tumour-is there an increased risk of periprosthetic infection by using a trevira tube?

BACKGROUND AND OBJECTIVES: The aim of our study was to evaluate if there is an increased risk of periprosthetic infection (PJI) in patients following replacement of the proximal humerus by using a modular tumour prosthesis in combination with a trevira tube. METHODS: Thirty patients were treated by using a modular tumour endoprosthesis (MUTARS®) following intra-articular resection of the proximal humerus. Fifteen patients received treatment by using a trevira tube. In 15 further cases the use of a trevira tube was not necessary. The mean follow-up time was 26 months (range: 24 months to 84 months). Both, Enneking score and range of motion (ROM), was evaluated. Further radiographs were obtained in two planes. RESULTS: The survival rate one year after surgery was 83 % and 63 % after two years. We recorded a 96 % survival of the limb two years after surgery. We also observed only one case of periprosthetic joint infection (PJI) in the entire follow-up period in one patient who received treatment with a trevira tube. The mean Enneking score was 20 points (range 8 to 26 points). ROM was equal in both study groups. In total 20 % of the treated patients (n = 6) suffered complications. CONCLUSIONS: Replacement of the proximal humerus by using a trevira tube in combination with a modular tumour endoprosthesis is a safe and viable treatment option for both, bone tumours and metastases. There is no statistically significant increased risk of infection by using trevira tube even among immunosuppressed patients. LEVEL OF EVIDENCE: Level 3, retrospective comparative study.

Functional and Rehabilitative Outcomes of Patients Affected by Bone Cancer of the Upper Limb Treated with MUTARS Prosthesis: A Narrative Review.

Megaprostheses are well-known, reliable, and effective reconstruction prostheses used in oncologic surgery for limb salvage in patients affected by primary or metastatic bone tumors. Rehabilitation plays a major role after MUTARS replacement, with the aim of improving function after surgery and maintaining the highest possible quality of life. Only a few studies have been published about the use of megaprostheses for the upper limb. The aim of this narrative review is to describe the results of functional and rehabilitative outcomes of patients affected by bone primary or metastatic bone cancer of the upper limb and surgically treated with MUTARS prostheses. A comprehensive search was conducted on PubMed and Scopus using the following MESH terms: "Mutars", "Megaprosthesis", "bone", "tumors", "metastasis", "upper limb", "rehabilitation", "outcome", "quality of life", and 10 studies were included. The most frequent oncological pathology was found to be metastases of the proximal humerus treated with modular endoprosthesis or modular reverse implants. Outcome measures used were ROM, MSTS, ASES, DASH, Constant-Murley score, Enneking score, VAS, MEP, TESS, and WOSI. Reconstruction of the proximal humerus with the MUTARS system seemed to be a valid treatment option after bone tumor resection. Rehabilitation after MUTARS surgery is very relevant, but currently, functional and rehabilitative outcomes are inadequately represented in the literature. Hence, further studies are needed to define standardized rehabilitation protocols after oncological orthopedic surgery that can be applied routinely in clinical practice.

Primary or revision arthroplasty with an integrated acetabular cup-MUTARS® RS cup system.

INTRODUCTION: The aim of this article is to show a new concept of indication and application of the MUTARS® RS Cup System in primary and revision hip arthroplasty. This integrated system is applicable for different acetabular cup replacements in patients with acetabular fractures or instable defects, as well as periprosthetic acetabular fractures. The MUTARS® RS Cup System is a cementless revision cup for insertion into the acetabulum with an integrated polyethylene cup, which fits to a regular or bipolar head. This system replaces the conventional approach for acetabular revision with a Burch-Schneider ring, in which a normal polyethylene cup is cemented. This interface with its complications is avoided with this system of a titanium revision cup with integrated polyethylene cup. Steps of preoperative planning and the intraoperative implementation will be highlighted in this article. MATERIAL AND METHODS: This system was applied in 49 patients with 52 MUTARS® RS Cup Implantations in 30 males, 22 females, with an average age of 76,1 years (36,9-94,4 years). RESULTS AND DISCUSSION: The system shows a good operative feasibility, as well as a reliable handling and safe method for stable treatment of non-reconstructable acetabular fractures or acetabular incongruencies and instabilities.

Acetabular fractures treatment needs in the elderly and nonagenarians.

Different treatment options for acetabular fractures in the elderly and nonagenarians exist; a consistent guideline has not been established, yet. The purpose of this study is to give an overview of how those fractures can be handled and compares two different surgical treatment methods. A total of 89 patients ≥ 18 years between 2016 and 2021 with acetabular fractures in our department received a surgical intervention with plate fixation via the Stoppa approach or a total hip arthroplasty with a Burch-Schneider ring and integrated cup. 60 patients ≥ 65 were compared in two groups, 29 patients between 65 and 79 and 31 patients ≥ 80. For comparison, data on operation times, hospitalization, complications during operation and hospital stay, blood loss and postoperative mobilization were collected. Characteristics could be found for indications for operative osteosynthesis or endoprosthetics based on the X-ray analysis. There was a tendency to treat simple fractures with osteosynthesis. Patients between 65 and 79 with an osteosynthesis had benefits in almost every comparison. Patients ≥ 80 with a plate fixation had advantages in the categories of postoperative complications, blood loss and transfusion of erythrocyte concentrates. Statistical significant differences were noticed in both groups regarding the operation time. Patients between 65 and 79 with osteosynthesis had significant benefits for postoperative complications, hospitalization, number of blood transfusions and postoperative mobilization. Finding the best supportive treatment option is difficult, and decision-making must respect fracture patterns and individual risk factors. This study shows that plate fixation via the Stoppa approach has some benefits.

MUTARS® Humero pro Femur replacement: A novel reconstructive procedure after malignant bone tumor resection of the femur in young children.

Limb-preserving surgery in young children suffering malignant bone tumor of the femur is challenging due to the specific anatomical conditions. Extendable tumor endoprostheses are often oversized, while custom-made endoprostheses do not provide the intraoperatively required variability regarding reconstruction length. Allo- and autograft replacements, on the other hand, show high complication and revision rates. We report a novel reconstructive procedure after resection of malignant bone tumors of the femur in young children, and present our preliminary results of this technique.

Critically high metal ion levels found in metal-on-metal modular hinged knee arthroplasty : a comparison of two different systems.

AIMS: This study compared the cobalt and chromium serum ion concentration of patients treated with two different metal-on-metal (MoM) hinged total knee arthroplasty (TKA) systems, as well as a titanium nitride (TiN)-coated variant. METHODS: A total of 63 patients (65 implants) were treated using either a MoM-coated (n = 29) or TiN-coated (n = 7) hinged TKA (GenuX mobile bearing, MUTARS; Implantcast, Germany) versus the BPKS (Brehm, Germany) hinged TKA (n = 27), in which the weight placed on the MoM hinge is diffused through a polyethylene (PE) inlay, reducing the direct load on the MoM hinge. Serum cobalt and chromium ion concentrations were assessed after minimum follow-up of 12 months, as well as functional outcome and quality of life. RESULTS: No differences in mean age (69 years, 40 to 86), mean age adapted Charlson Comorbidity Index (3.1 (SD 1.4)), mean BMI (29.2 kg/m2 (SD 5.8)), or number of other implants were observed between groups. Significant improvements in outcome scores and pain levels were achieved for all groups, and there was no difference in quality of life (12-Item Short-Form Health Survey questionnaire (SF-12)). Mean cobalt and chromium ion levels were significantly higher for the GenuX versus the BPKS hinged TKA (GenuX vs BPKS: cobalt: 16.3 vs 9.4 µg/l; chromium: 9.5 vs 5.2 µg/l). The TiN-coated implants did not appear to confer improvement in the metal ion levels. Metal ion concentrations above 7 µg/l were detected in 81%(29/36) of GenuX patients versus 41% (11/27) in the BPKS group. No GenuX patients had normal levels under 2 µg/l, versus 22% of BPKS patients. No significant reduction in outcome scores was observed regardless of the metal ion levels, whereas higher work-related activity was correlated with higher chromium concentrations. CONCLUSION: Hinged TKA, using MoM hinges, resulted in critically high cobalt and chromium ion concentrations. The BPKS hinged TKA showed significantly lower metal ion concentrations compared with the GenuX TKA. No benefits were observed using TiN coating. The different weightbearing mechanics might influence the wear of the component materials. Higher workloads and physical activity could influence chromium levels. Cite this article: Bone Joint J 2022;104-B(3):376-385.