Background: Chronic prosthetic joint infection is a cause of patient morbidity and can be challenging to treat. Surgeons performing revision arthroplasty of the hip and knee are confronted with a growing number of patients with extensive loss of bone stock. The use of a modular endoprosthesis is a possible method of treatment in such patients. Aim: The purpose of this study was to assess the functional outcomes and the success of a single and two stage revision procedure in eradicating chronic prosthetic joint infection using a femoral endoprosthesis. Methods: A prospective database was reviewed of 20 patients who underwent a proximal, total or distal femoral endoprosthetic replacement after chronic prosthetic infection. Radiographs performed at the time of latest follow up were evaluated for signs of loosening, osteomyelitis and implant failure. The functional status was assessed using the Short Form (SF)-36 health survey score, Toronto extremity salvage score (TESS) and the Enneking score. Results: Thirteen patients underwent a single stage revision procedure and seven had been treated with a staged revision. At the latest follow up none of the 13 patients treated with a single stage procedure had evidence of ongoing infection. Of the seven patients who had a staged revision, 3 patients had evidence of ongoing infection. The mean pre operative Enneking score for the entire group was 17.1 points and this improved to 47.5 points post operatively (p< 0.0002). The mean pre operative TESS score for the entire group was 42% and this improved to 59% post operatively (p< 0.005). There was also a statistically significant improvement in all of the components of the SF-36 score. Conclusion: We believe that the use of a modular endo-prosthesis in the treatment of chronic prosthetic joint infection is a successful and viable option in eradicating infection, preserving the limb and providing a good functional result

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

Background: Endoprosthetic reconstruction has become the gold standard of treatment after the resection of tumors around the proximal femur, however, the rate of complications linked to megaprostheses is clearly higher than with standard implants. Aim of this study was to investigate the incidence and type of complications related to modular proximal femur prostheses. Patients and Methods: By retrospective database analysis of the Vienna Tumor Registry, we evaluated the incidence of complications in 170 consecutive patients who have received a proximal femur KMFTR/GMRS at our institution between 1982 and 2007. 71 patients with an average age of 41.7 years (range 18.2–79.9 years) received the implant following the resection of a malignant bone tumor, 95 patients with an average age of 61.7 years (range 5.9–84.2 years) due to metastatic disease. The average time of follow-up was 3.5 years (SD ±4.9 years). Results: Overall patient survival at five years was 32%. For patients with metastatic disease the overall survival was 10% at five years. Patients being treated for a primary bone tumor had an overall survival of 55% at 5 years. The overall survival of the prosthesis was 90% at two years and 72% at five years. Twenty-one patients (12.65%) suffered from dislocation after a mean time of 6.5 month (range 0.3–33 months) after surgery. Out of these, nine had to be treated by open reduction. Nine patients suffered recurrent dislocation after their first event. Patients who underwent extensive pelvic reconstruction had a significantly higher dislocation rate (33.3%) compared to patients with no or standard acetabular components (11.2%). Deep infection occurred in twelve patients (7.3%) after a mean of 39 months (range 1–166 months) after surgery. Treatment of infection was one-stage revision in eight and hip disarticulation in one patient. Two patients were successfully treated by local wound revision. One patient died of septic shock four days after surgery. Re-infection occurred in three patients. Aseptic loosing occurred in 13 patients (12.8%) after a mean time of 75.6 months (range 1–223 months) after surgery. Revision surgery was necessary in 27 patients (15.8%) with a mean time to first revision of 32 months (range 0.3–116 months). Prosthetic fracture was found in two patients. Local recurrence occurred in 14 patients (8.4%). In seven patients (4.2%) amputation was necessary. Conclusion: Modular endoprosthesis allow excellent reconstruction of the proximal femur following tumor resection. However, the main complications, dislocation and infection, still remain considerable drawbacks

Aims

For rare cases when a tumour infiltrates into the hip joint, extra-articular resection is required to obtain a safe margin. Endoprosthetic reconstruction following tumour resection can effectively ensure local control and improve postoperative function. However, maximizing bone preservation without compromising surgical margin remains a challenge for surgeons due to the complexity of the procedure. The purpose of the current study was to report clinical outcomes of patients who underwent extra-articular resection of the hip joint using a custom-made osteotomy guide and 3D-printed endoprosthesis.

Introduction. Dual modular hip prostheses were introduced to optimize the individual and intra-surgical adaptation of the implant design to the native anatomics und biomechanics of the hip. The downside of a modular implant design with an additional modular interface is the potential susceptibility to fretting, crevice corrosion and wear [1–2]. The purpose of this study was to characterize the metal ion release of a modular hip implant system with different modular junctions and material combinations in consideration of the corrosive physiological environment. Methods. One design of a dual modular hip prosthesis (Ti6Al4V, Metha®, Aesculap AG, Germany) with a high offset neck adapter (CoCrMo, CCD-angle of 130°, neutral antetorsion) and a monobloc prosthesis (stem size 4) of the same implant type were used to characterize the metal ion release of modular and non-modular hip implants. Stems were embedded in PMMA with 10° adduction and 9° flexion according to ISO 7206-6 and assembled with ceramic (Biolox® delta) or CoCrMo femoral heads (XL-offset) by three light impacts with a hammer. All implant options were tested in four different test fluids: Ringer's solution, bovine calf serum and iron chloride solution (FeCl3-concentration: 10 g/L and 114 g/L). Cyclic axial sinusoidal compressive load (Fmax = 3800 N, peak load level of walking based on in vivo force measurements [3]) was applied for 10 million cycles using a servohydraulic testing machine (MTS MiniBionix 370). The test frequency was continuously varied between 15 Hz (9900 cycles) followed by 1 Hz (100 cycles). The metal ion concentration (cobalt, chromium and titanium) of the test fluids were analysed using ICP-OES and ICP-MS at intervals of 0, 5·105, 2·106 and 10·106 cycles (measuring sensitivity < 1 µg/L). Results. Due to the additional modular interface between stem and neck adapter the total metal ion release of the modular hip endoprosthesis system increased significantly and is comparable to the coupling of a monobloc stem and a CoCrMo femoral head (Fig. 1). The application of ceramic femoral heads reduced the total cobalt and chromium release in the stem-head taper interface of non-modular and modular stems. In comparison between the four test fluids could be observed that lower pH-values and higher FeCl3-concentrations increased the metal ion release (Fig 2). In contrast, the use of bovine calf serum decreased the metal ion release of modular junctions due to the presence of proteins and other organic components. Discussion. For testing hip implants with proximal femoral modularity according to ISO and ASTM standards, sodium chloride solutions are frequently used to determine the fatigue strength and durability of the stem-neck connection. The present study illustrate that the expansion of standard requirements of biomechanical testing and the use of alternative test fluids is necessary to simulate metal ion release by electro-chemical processes. A promising approach is the use of adapted iron-chloride solutions (10 g/L FeCl3, pH 2) to evaluate the susceptibility of modular hip junctions to fretting, crevice and contact corrosion

The August 2015 Oncology Roundup³⁶⁰ looks at: Glasgow prognostic score in soft-tissue sarcoma; Denosumab in giant cell tumour; Timing, complications and radiotherapy; Pigmented villonodular synovitis and arthroscopy; PATHFx: estimating survival in pathological cancer; Prosthetic lengthening of short stumps; Chondrosarcoma and pathological fracture

The December 2013 Oncology Roundup³⁶⁰ looks at: Peri-articular resection fraught with complications; Navigated margins; Skeletal tumours and thromboembolism; Conditional survival in Ewing’s sarcoma; Reverse shoulders and tumour; For how long should we follow up sarcoma patients?; and already metastasised?