Endoprosthetic replacements for bone tumors: review of the most recent literature

Infections of Tumor Prostheses: An Updated Review on Risk Factors, Microbiology, Diagnosis, and Treatment Strategies

Several causes contribute to the high infection rate in tumor prostheses, including extensive tissue dissection and patients' immunosuppression due to the neoplastic disease. Most of these infections develop within the first 2 years following surgery with 70% of them occurring during the first year, while they are often associated with a low pathogen burden. The pathogenesis of infections in tumor prostheses is linked to bacteria developing in biofilms. Approximately half of them are caused by Staphylococcus spp., followed by Streptococcus spp., Enterococcus spp., and Enterobacteriaceae spp., while multiple pathogens may be isolated in up to 25% of the cases, with coagulase-negative Staphylococci (CoNS) and Enterococccus spp. being the most frequent pair. Although early detection and timely management are essential for complete resolution of these challenging infections, prompt diagnosis is problematic due to the highly varying clinical symptoms and the lack of specific preoperative and intraoperative diagnostic tests. Surgical management with one- or two-stage revision surgery is the mainstay for successful eradication of these infections. The recent advances in laboratory diagnostics and the development of biofilm-resistant prostheses over the past years have been areas of great interest, as research is now focused on prevention strategies. The aim of this study is to review and consolidate the current knowledge regarding the epidemiology, risk factors, microbiology, and diagnosis of infections of tumor prostheses, and to review the current concepts for their treatment and outcomes.

Very long-term outcomes after endoprosthetic replacement for malignant tumours of bone

AIMS

The aim of this study was to establish what happens to patients in the long term after endoprosthetic replacement for a primary malignant tumour of bone.

PATIENTS AND METHODS

We conducted a retrospective analysis of a prospectively maintained database to identify all patients who had undergone an endoprosthetic replacement more than 25 years ago and who were still alive. Their outcomes were investigated with reference to their complications and need for further surgery. A total of 230 patients were identified. Their mean age at diagnosis was 20.7 years (five to 62). The most common diagnosis was osteosarcoma (132). The most common site was the distal femur (102).

RESULTS

The mean follow-up was 29.4 years (25 to 43). A total of 610 further operations were undertaken, an average of 2.7 further operations per patient. A total of 42 patients (18%) still had the original prosthesis in place. The risk of amputation was 16% at 30 years (31 patients). Those without infection had a mean of 2.1 further operations (one to nine) while those with infection had a mean of 4.6 further operations (two to 11). The risk of infection persisted throughout the life of the prosthesis with a mean of 1% per year becoming infected. Of the 60 patients who developed an infection, 21 (35%) developed this following the primary procedure at a mean of 50 months, but another 19 developed this within a year of another surgical procedure. The risk of infection after any further surgery was 2.7%. The site with the highest risk of infection was the proximal tibia (43.3%).

TAKE HOME MESSAGE

This study highlights the inevitable need for further surgery following first-generation endoprosthetic reconstruction, although in most cases, limb salvage is maintained. Late complications, especially infection, continue for the lifetime of the implant. Cite this article: Bone Joint J 2016;98-B:857-64.

Survival of current production tumor endoprostheses: complications, functional results, and a comparative statistical analysis

BACKGROUND AND OBJECTIVES

Retrospectively analyze outcomes of current-generation Global Modular Replacement System (GMRS) modular tumor endoprosthesis for the lower limb in primary and secondary implantation procedures.

METHODS

Two hundred ninety five prostheses were implanted, 197 were primary implants, 98 were for revision surgery; revision procedures included 84 failed tumor reconstructions and 14 failed non-tumor reconstructions. Anatomic sites included: distal femur 199; proximal tibia 60; proximal femur 32;total femur 4. Endoprosthesis failures were classified as soft-tissue failures (Type 1), aseptic loosening (Type 2), structural fracture (Type 3), infection (Type 4), and tumor recurrence (Type 5). MSTS functional scores were measured.

RESULTS

The overall failure rate was 28.8% and failure occurred at a median of 1.7 years (range, 1 month to 7 years). At a mean oncologic follow up of 4.2 years (range, 2-8 years), 195 patients are continuously NED, 43 NED after treatment of relapse, 10 AWD, 33 DWD. There was a significant difference in implant survival of all modes of failure between primary and revision implants (P = 0.03). No prosthetic fracture occurred. The average functional score was 81.6% (24.5).

CONCLUSIONS

Mid-term results with GMRS are promising, with good functional results and low incidence of complications for primary implants.

LEVEL OF EVIDENCE

Therapeutic study, level IV-1 (case series).

Infected tumor prostheses

Infection of tumor prostheses has been a major concern because of the extensive soft tissue dissection, long operating times, and patients' immunosuppression by cancer and adjuvant treatments. Infections most often present within 2 years postoperatively, with approximately 70% of postoperative deep infections presenting within 12 months after surgery. They are typically low organism burden infections, the pathogenesis of which is related to bacteria growing in biofilms. Staphylococci are the most common pathogens involved in prosthetic joint infections, accounting for approximately 50% of infections overall, followed by streptococci, enterococci, Enterobacteriaceae species, Pseudomonas aeruginosa, and anaerobe species. Multiple pathogens may be isolated in approximately 25% of cases, with the most common combination being coagulase-negative Staphylococcus and group-D Streptococcus. Early diagnosis and appropriate treatment are necessary. However, diagnosis may be challenging because clinical symptoms are highly variable and numerous preoperative and intraoperative diagnostic laboratory tests are nonspecific. In most cases, a 1- or 2-stage revision surgery is necessary for eradicating the megaprosthetic infection. Prevention of infection is important. The future will see technical advances for infections of tumor prostheses in areas such as microbiological diagnostics and biofilm-resistant prostheses.

Advances in segmental endoprosthetic reconstruction for extremity tumors: a review of contemporary designs and techniques

BACKGROUND

Improved understanding and advances in treatment regimens have led to increased longevity among patients diagnosed with extremity soft tissue sarcomas. Limb salvage techniques and implants have improved and continue to evolve to accommodate the increasing demands and survival of these patients.

METHODS

The current report is a review of the literature for recent advancements in techniques, implant design, and outcomes in the field of limb salvage therapy using segmental megaprostheses for the treatment of extremity sarcomas. We report on our experience in this field utilizing a classification system of failure mechanisms to outline to discuss current controversies in management.

RESULTS

Five mechanisms of failure have been identified: soft-tissue failure, aseptic loosening, structural failure, infection, and tumor progression. Infection was the most common mode of failure in our series, accounting for 34% of cases. Soft-tissue failure occurred most commonly in the joints that depend heavily on periarticular muscles and ligaments for stability due to their high degree of functional range of motion. We observed a 28% soft-tissue failure rate about the shoulder and hip, aseptic loosening accounted for 19% of implant failures, and structural failure was seen in 17% of cases. Seventeen percent of cases failed due to tumor progression, an etiology that is defined by biological factors, surgical technique, and adjuvant therapies.

CONCLUSIONS

Surgical techniques and megaprosthesis designs are constantly changing in order to meet the challenge of increasing functional demands and longevity in this unique patient population. A classification system defined by treatment failure etiologies provides the framework for discussion of current controversies in limb salvage therapy as well as a guide for advancement and potential solutions in this challenging arena.

Disassembly of a distal femur modular prosthesis after tumor resection

We report and analyze the causes of a disassembly of a newly marketed distal femur modular prosthesis in a 20-year-old man with stage IIB osteosarcoma. The disassembly occurred after discharge from the hospital, after a minor trauma. Because of the unique displacement of the femoral component, sudden operative management was performed. Disassembly should be considered as a potential complication when choosing a modular prosthesis despite improvements in the design of some recent devices. In cases with a substantial amount of functional muscle excised at the time of tumor resection, adequate postoperative rehabilitation is recommended.