Aims

Over time, the locking mechanism of Modular Universal Tumour and Revision System (MUTARS) knee arthroplasties changed from polyethylene (PE) to polyether-ether-ketone Optima (PEEK) and metal-on-metal (MoM) in an attempt to reduce the risk of mechanical failure. In this study, we aimed to assess the cumulative incidence of locking mechanism revision for symptomatic instability by type of material, and assess potential associated risk factors.

Objectives

Preclinical data showed poly(methyl methacrylate) (PMMA) loaded with microsilver to be effective against a variety of bacteria. The purpose of this study was to assess patient safety of PMMA spacers with microsilver in prosthetic hip infections in a prospective cohort study.

Aim. The aim of this study was to analyze our results using a modular endoprosthetic replacement system (MUTARS) for bone tumours of the proximal humerus. Methods. Thirty-nine patients were treated with a MUTARS endoprosthesis of the proximal humerus. Mean follow-up was 38 months (3-138 months). Most operations were necessitated by metastasis (n=30); surgery for a primary tumour (n=9) was less frequent. The Enneking score and the active ranges of motion for shoulder flexion, abduction, and external rotation were recorded. Complete refixation of the rotator cuff was possible in 23 cases. Radiographs also were obtained. Results. Patient survival was 77% at 2 years and 45% at 11.5 years after surgery. The survival rate of the limb was 90% at 11.5 years. The mean Enneking score was 19 points (range 7-27 points). The mean shoulder flexion was 34 degrees (range 0-90 degrees), abduction 33 degrees (range 0-90 degrees), and external rotation 12 degrees (range 10-50 degrees). Patients with a complete rotator cuff repair showed a significant better range of motion compared to patients with a partial or no repair (p<0.015). No signs of implant loosening were observed on postoperative radiographs. Seven complications occurred, five of them leading to implant revision. At 11.5 years after surgery, the survival rate for the whole cohort without complications was 72%, without revision of the implant 70%. Conclusion. Replacement of the proximal humerus with MUTARS endoprosthesis is a viable treatment option for bone tumours with satisfying results

A retrospective study focusing on long-term follow up of 28 patients with a malignant bone tumour in the distal femur was conducted. Patients with a mean age of 50 (18–90) were clinically and radiologically followed-up for a mean period of 64 months (7–144). Osteosarcoma was the most common primary bone tumour, occurring in 15 patients. The 5-year survival for all patients was 80,9%. At final follow-up, 19 patients were still alive and had a mean follow up of 74,6 months (7–137). Clinical evaluation was done with the MSTS questionnaire (mean score: 70,0 (26,7–93,3)) and the use of the TESS (mean score: 82,5 (45–99,2) and SF-36 (mean Physical Component Score (PCS): 46,6 (27,1–56,5), mean Mental Component Score (MCS): 53,7 (range 37,0–62,1) was introduced. There were 12 complications: 5 aseptic loosenings, two deep prosthetic infections, two luxations, one prosthetic fracture and two fissures. Six failures were re-operated. An overall prosthetic survival at 5-years of 77,0 % was found. A total of eight (29%) prostheses were considered to have failed after a mean follow up of 27,4 months (0–97). Risk factors in failure of the prosthetics were: non HA-coated stem and top stem-ratio > 1.2. Not length of the endoprosthesis and base stem-ratio. The top-ratio had a mean value of 1,14 (1,00–1,52) and for the four patients with an aseptic loosening the mean top-ratio was 1,23 (1,12–1,51) which was significantly different (p< 0,05 Mann-Whitney U test). Our results suggest that of the MUTARS endoprosthesis has a good 5-year survival. The use with a HA coating is preferable. The use of a stem-cortex ratio (> 1.2) at the top of the prosthetic stem can be predictor for aseptic loosening. The addition of the TESS and SF-36 scores give more insight information in how patients undergo their disease: half do not feel disabled

From 1992 on 2008, 615/515 patients underwent primary or revisional endoprosthetic replacement of major joints. In 51 patients (31 men & 20 women) modular system MUTARS (Implantcast, Germany) has been used. The median age was 23.3 years (15 to 52 years). MUTARS modular endoprosthesis has been used in 10 patients with deep infection of endoprosthetic bed as a revisional endoprosthetic replacement: 1 Total endoprosthetic replacement of femur, 5 Total knee joint replacement (2 for distal femoral defect and 3 for proximal tibial defect). In 3(27%) patients, we used newly patented silver ion coated MUTARS either after two stage treatment for infection of endoprosthetic bed or as a prophylaxis of endoprosthetic infection. In 1 patient (23 yrs), with 12cm limb length shortening, we used extensible MUTARS as a revisional endoprosthetic replacement. The following complications we observed: Instability of endoprosthesis – 3/51 (5.9%), deep endoprosthetic bed infection – 4/51 (7.8%). In comparison group, when using custom-made endoprosthesis, the frequency of infectious complications have made 60/574 (10.5 %), and instability of implants was observed in 79/574 (13.8 %) cases. Transition of using modular systems for primary and revisional endoprosthesis allows to reduce the level of instability from 13.8 % to 5.9 %. The quantity of infectious complications is also not great as in comparison with control group. For revisional endoprosthetic replacement, we think, the given modular system is optimal, for correcting limb length deficiency and restoration of basic function at patients. Use of silver ion coated modular implants is a promising method for treating deep endoprosthetic bed infection