Characteristics and outcome of infections associated with tumor endoprostheses

Silver-Coated Megaprosthesis of the Proximal Tibia in Patients With Sarcoma

BACKGROUND

Proximal tibia arthroplasty is associated with high rates of infection. This study is the largest one that has compared the infection rates with titanium vs silver-coated megaprostheses in patients treated for sarcomas.

METHODS

The infection rate in 98 patients with sarcoma or giant-cell tumor in the proximal tibia who underwent placement of a titanium (n = 42) or silver-coated (n = 56) megaprosthesis (MUTARS) was assessed, along with the treatments administered for any infection.

RESULTS

As the primary end point of the study, the rates of infection were 16.7% in the titanium group and 8.9% in the silver group, resulting in 5-year prosthesis survival rates of 90% in the silver and 84% in the titanium group. Whereas in the titanium group 37.5% of patients ultimately had to undergo amputation in the present study, these mutilating surgical procedures were only necessary in the silver group in one patient (14.3%).

CONCLUSION

The use of silver-coated prosthesis reduced the infection rate in a relatively large and homogeneous group of patients. In addition, less-aggressive treatment of infection was possible in the group with silver-coated prosthesis.

pH dependent silver nanoparticles releasing titanium implant: A novel therapeutic approach to control peri-implant infection

Peri-implant infection control is crucial for implant fixation and durability. Antimicrobial administration approaches to control peri-implant infection are far from satisfactory. During bacterial infection, pH level around the peri-implant surface decreases as low as pH 5.5. This change of pH can be used as a switch to control antimicrobial drug release from the implant surface. Silver nanoparticles (AgNPs) have broad-spectrum antimicrobial properties. In this study, we aimed to design a pH-dependent AgNPs releasing titania nanotube arrays (TNT) implant for peri-implant infection control. The nanotube arrays were fabricated on the surface of titanium implant as containers; AgNPs were grafted on TNT implant surface via a low pH-sensitive acetal linker (TNT-AL-AgNPs). SEM, TEM, AFM, FTIR as well as XPS data showed that AgNPs have been successfully linked to TNT via acetal linker without affecting the physicochemical characteristics of TNT. The pH 5.5 enhanced AgNPs release from TNT-AL-AgNPs implant compared with pH 7.4. AgNPs released at pH 5.5 robustly increased antimicrobial activities against gram-positive and gram-negative bacteria compared with AgNPs released at pH 7.4. TNT-AL-AgNPs implant enhanced osteoblast proliferation, differentiation, and did not affect osteoblast morphology in vitro. In conclusion, incorporation of AgNPs in TNT via acetal linker maintained the surface characteristics of TNT. TNT-AL-AgNPs implant was biocompatible to osteoblasts and showed osteoinductive properties. AgNPs were released from TNT-AL-AgNPs implant in high dose at pH 5.5, and this release showed strong antimicrobial properties in vitro. Therefore, this novel design of low pH-triggered AgNPs releasing TNT-AL-AgNPs could be an infection-triggered antimicrobial releasing implant model to control peri-implant infection.

Megaprosthesis of the knee in tumor and revision surgery

The introduction of multidisciplinary approach with chemo and radiotherapy, the advances in surgical and the improvements of diagnostic techniques allowed limb salvage surgery in most cases of bone sarcomas instead of amputation. Modular megaprostheses are the most common method of reconstruction after segmental resection of the long bones in the extremities for their availability, immediate fixation, early weight bearing, good function. Despite the advances in materials and implant designs, these systems have an high incidence of complications. Aim of this study was to report the experience on mega-prostheses implanted around the knee in tumor and revision surgery to analyze: the most frequent used current systems, the problems of stems fixation, extensor mechanism reconstructions in proximal tibia resections and the preservation of growth of the lower extremity in children.

Megaprosthesis of the knee in tumor and revision surgery

The introduction of multidisciplinary approach with chemo and radiotherapy, the advances in surgical and the improvements of diagnostic techniques allowed limb salvage surgery in most cases of bone sarcomas instead of amputation. Modular megaprostheses are the most common method of reconstruction after segmental resection of the long bones in the extremities for their availability, immediate fixation, early weight bearing, good function. Despite the advances in materials and implant designs, these systems have an high incidence of complications. Aim of this study was to report the experience on mega-prostheses implanted around the knee in tumor and revision surgery to analyze: the most frequent used current systems, the problems of stems fixation, extensor mechanism reconstructions in proximal tibia resections and the preservation of growth of the lower extremity in children. (www.actabiomedica.it)

High blood metal ion levels in 19 of 22 patients with metal-on-metal hinge knee replacements

Background and purpose - There has been increasing alarm regarding metal-on-metal (MoM) joint replacements leading to elevated levels of metal ions and adverse reactions to metal debris (ARMDs). There is little information available concerning the prevalence of and risk factors for these adverse reactions, except with MoM hip joint replacements. We determined the levels of metal ions in blood and the rate of revision due to ARMDs in patients treated with MoM hinge total knee arthroplasty (TKA). Patients and methods - 22 patients with TKAs and MoM hinge connecting mechanisms were studied for whole-blood chromium and cobalt levels at 6 months, 1 year, and/or ≥2 years after surgery. Possible ARMDs were investigated by MRI. 12 patients with TKAs and metal-on-polyethylene (MoP) connecting mechanisms served as controls. Results - The cobalt levels were over 5 ppb in 19 of the 22 patients in the MoM group and in 1 of the 12 patients in the MoP group. The chromium levels were over 5 ppb in 11 of the 22 patients in the MoM group and in none of the 12 patients in the MoP group. Pseudotumors were operated in 4 of the 22 patients in the MoM group and in none of the patients in the MoP group. Interpretation - Our results clearly show that the MoM hinge TKA carries a high risk of increased levels of systemic metal ions and also local ARMD, leading to complicated knee revisions. We therefore discourage the use of MoM hinge TKA.

Imaging of Complications After Limb Prostheses Implantation in Children with Bone Tumors

BACKGROUND

Tumors of the developmental age are an important problem in clinical practice. Primary bone tumors constitute 1-1.5% of all tumors, and 7% of all tumors diagnosed in the developmental age. The aim of the study was to assess the capabilities of imaging methods in diagnosing complications of limb endoprostheses in children with osteoarticular tumors.

MATERIAL/METHODS

We included 155 patients with limb endoprostheses, aged 7-26 years. There were 113 patients with knee prostheses, 1 patient with bilateral knee prostheses, 16 patients with shoulder prostheses, 14 patients with hip prostheses, 11 patients with hip and knee prostheses, and 1 patient with a femoral prosthesis. All patients underwent plain radiography and an ultrasound study.

RESULTS

Complications were found in 50 patients (32% of all patients). The following complications were seen - inflammatory changes in soft tissues and bones (12 patients, 7.7%), stump fractures (11 patients, 7%), lack of elongation effect or shortening of the prosthesis (7 patients, 4.5%), prosthesis fractures (4 patients, 2.5%), crural fractures (4 patients, 2.5%), loosening of the prosthesis (3 patients, 1.9%), joint dislocation (2 patients, 1.3%), stump and prosthesis fracture (1 patient, 0.6%) and local recurrence (6 patients, 3.9%). Prostheses were exchanged for the following reasons - fractures (5 patients, 3.2%), inflammation (2 patients with 3 exchanges, 1.9%). Local recurrence and inflammation were confirmed by a biopsy.

CONCLUSIONS

Radiography and ultrasonography are of crucial importance in monitoring patients after implantation of limb endoprostheses. The findings did not require confirmation in additional studies: CT and MRI. Suspicion of local recurrence and inflammation required a biopsy confirmation.

Silver-coated megaprostheses: review of the literature

Periprosthetic infection remains one of the most serious complications following megaendoprostheses. Despite a large number of preventive measures that have been introduced in recent years, it has not been possible to further reduce the rate of periprosthetic infection. With regard to metallic modification of implants, silver in particular has been regarded as highly promising, since silver particles combine a high degree of antimicrobial activity with a low level of human toxicity. This review provides an overview of the history of the use of silver as an antimicrobial agent, its mechanism of action, and its clinical application in the field of megaendoprosthetics. The benefits of silver-coated prostheses could not be confirmed until now. However, a large number of retrospective studies suggest that the rate of periprosthetic infections could be reduced by using silver-coated megaprostheses.

What Are the Functional Results and Complications With Long Stem Hemiarthroplasty in Patients With Metastases to the Proximal Femur?

BACKGROUND

Traditional treatments for pathological fractures of the proximal femur resulting from metastatic bone disease include fixation with intramedullary nailing supplemented with polymethylmethacrylate, osteosynthesis with a plate-screw construct and polymethylmethacrylate, or endoprosthetic reconstruction. Despite the frequent practice of these treatments, treatment outcomes have not been rigorously compared. In addition, very few studies examine specific approaches to endoprosthetic reconstruction such as long stem hemiarthroplasty.

QUESTIONS/PURPOSES

This study examines survival, functional outcomes, and complications associated with long stem hemiarthroplasty in a small group of patients treated for impending and actual pathologic fractures of the proximal femur resulting from metastatic bone disease.

METHODS

Between 2012 and 2015, 21 patients were treated with long stem cemented hemiarthroplasty in 22 limbs. During that time, indications for this approach included lesions from metastases, myeloma, or lymphoma involving the proximal femur that resulted in an impending or actual pathological fracture. An impending fracture was classified as a painful lesion with at least 50% cortical erosion. During the study period, six patients with proximal femoral metastases not deemed to meet these indications were treated with other surgical approaches such as intramedullary nailing supplemented with polymethylmethacrylate and osteosynthesis with a plate-screw construct and polymethylmethacrylate. Mortality was tracked through medical records and phone calls to the patients and their families. Followup for the entire group of patients (n = 22) ranged from 1 to 27 months with a mean duration of 11 months. For patients with at least 1 year of followup (n = 11), the mean duration was 18 months (range, 12-27 months) and for patients with less than 1 year of followup (n = 11), the mean duration was 3 months (range, 1-11 months). Functional outcomes were evaluated according to the Musculoskeletal Tumor Society (MSTS) scoring system for lower extremities, the Eastern Cooperative Oncology Group (ECOG) Scale of Performance Status, and the Karnofsky Performance Scale (KPS) Index. Scores and complications were determined by direct patient examination, retrospective chart review, review of a longitudinally maintained institutional database, and followup phone calls.

RESULTS

Ten patients died of disease within the followup period. Before surgery, the median total MSTS score for the entire group of patients (n = 22) was 4.5 (range, 0-23), the median ECOG score was 3.5 (range, 1-4), and the median KPS score was 40 (range, 30-70). Postoperatively, the median total MSTS score (measured at most recent followup) for the entire group of patients was 21 (range, 5-30), the median ECOG score was 2 (range, 0-3, 68% ≤ 2), and the median KPS score was 60 (range, 40-100). For the 11 patients with at least 1 year of followup, the median total MSTS score (measured at most recent followup) was 27 (range, 21-30), the median ECOG score was 1 (range, 0-2, 100% ≤ 2), and the median KPS score was 80 (range, 60-100). For the remaining 11 patients with less than 1 year of followup, the median total MSTS score (measured at most recent followup) was 11 (range, 5-25), the median ECOG score was 3 (range, 1-3, 36% ≤ 2), and the median KPS score was 40 (range, 40-80). Complications included one periprosthetic fracture resulting from a fall, three cases of radiation-induced edema, and two cases of sciatica that developed unrelated to the procedure.

CONCLUSIONS

Long stem cemented hemiarthroplasty results in fair levels of function in a complex population of patients whose prognosis is sometimes measured only in months and who otherwise might be disabled by their metastatic lesions. Comparative trials applying consistent indications and inclusion criteria should be performed between this approach and fixation with intramedullary nailing supplemented with polymethylmethacrylate as well as osteosynthesis with a plate-screw construct and polymethylmethacrylate.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Selective laser melting porous metallic implants with immobilized silver nanoparticles kill and prevent biofilm formation by methicillin-resistant Staphylococcus aureus

Implant-associated infection and limited longevity are two major challenges that orthopedic devices need to simultaneously address. Additively manufactured porous implants have recently shown tremendous promise in improving bone regeneration and osseointegration, but, as any conventional implant, are threatened by infection. In this study, we therefore used rational design and additive manufacturing in the form of selective laser melting (SLM) to fabricate porous titanium implants with interconnected pores, resulting in a 3.75 times larger surface area than corresponding solid implants. The SLM implants were biofunctionalized by embedding silver nanoparticles in an oxide surface layer grown using plasma electrolytic oxidation (PEO) in Ca/P-based electrolytes. The PEO layer of the SLM implants released silver ions for at least 28 days. X-ray diffraction analysis detected hydroxyapatite on the SLM PEO implants but not on the corresponding solid implants. In vitro and ex vivo assays showed strong antimicrobial activity of these novel SLM PEO silver-releasing implants, without any signs of cytotoxicity. The rationally designed SLM porous implants outperformed solid implants with similar dimensions undergoing the same biofunctionalization treatment. This included four times larger amount of released silver ions, two times larger zone of inhibition, and one additional order of magnitude of reduction in numbers of CFU in an ex vivo mouse infection model.

Lower limb reconstruction in tumor patients using modular silver-coated megaprostheses with regard to perimegaprosthetic joint infection: a case series, including 100 patients and review of the literature

PURPOSE AND OBJECTIVE

Bone resection regarding adequate surgical margins is the treatment of choice for malignant bone tumors. In the case of metastasis-related complications, so-called skeletal-related events, it is highly important to achieve pain relief and a stable joint situation to re-mobilize the patients immediately following surgery. To bridge the often large osseous defect zones after tumor resection, both cemented and uncemented modular endoprosthetic systems are widely used. Patients undergoing tumor-related endoprosthetic orthopedic surgery are facing high risk for developing a periprosthetic joint infection (PJI). The immunocompromised condition due to anti-neoplastic treatment and long operation time with large exposure of tissue contributes to a high risk of infection.

METHODS

The authors present a case series of 100 patients (31% primary bone tumor and 69% metastasis-related surgery) undergoing tumor-related lower limb salvage surgery with special regard to periprosthetic joint infection and the management of this "difficult to treat" situation. Furthermore, a review of the current literature regarding infection following bone tumor resection and endoprosthetic reconstruction is performed and discussed.

RESULTS

The median follow-up was 24 months (range 12-108 months). Ten patients (10%) suffered from a periprosthetic joint infection. We recorded six acute infections (type I) <4 weeks after surgery, one infection >4 weeks after surgery (type II), and three late infections (type III). According to the definition of Laffer et al., three of our patients (30%) are probably free of infection, one patient died of PJI-associated sepsis, and five patients were free of infection, but without restoration of the affected joint.

CONCLUSION

In conclusion, our own results show that perimegaprosthetic joint infection among silver-coated implants, in patients undergoing tumor-related surgery of the lower limb, is lower compared to non-silver-coated implants. Due to heterogeneity of patients and potential treatment options, the treatment regime should be tailored for the patients' individual situation.

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.

Risk Factors for Perimegaprosthetic Infections After Tumor Resection

Periprosthetic joint infection remains one of the most challenging and pervasive complications following megaprosthetic replacement after tumor resection. The authors conducted a systematic review of the literature for clinical studies that reported a risk factor analysis for perimegaprosthetic joint infections. The search included English-language studies published up to July 2015. Eight studies fulfilled the inclusion criteria. Identified factors mostly related to both surgical procedure and hospitalization. Physicians should consider these results when discussing the outcomes of limb salvage surgery with patients and trying to reduce the overall burden of perimegaprosthetic joint infections. [Orthopedics. 2017; 40(1):e11-e16.].

Modular Endoprostheses for Nonneoplastic Conditions: Midterm Complications and Survival

The use of modular endoprostheses is a viable option to manage both tumor resection and severe bone loss due to nonneoplastic conditions such as fracture sequelae, failed osteoarticular grafts, arthroplasty revisions, and periprosthetic fractures. We sought to investigate both midterm complications and failures occurred in 87 patients who underwent a megaprosthetic reconstruction in a nonneoplastic setting. After a mean follow-up of 58 (1–167) months, overall failure-free survival was 91.5% at 1 year, 80% at 2 years, 71.6% at 5 years, and 69.1% at 5 and 10 years. There was no significant difference in the survival rate according to the diagnosis at the index procedure (p = 0.921), nor to the reconstruction site (p = 0.402). The use of megaprostheses in a postneoplastic setting did not affect survival rate in comparison with endoprosthetic reconstruction of pure nonneoplastic conditions (p = 0.851). Perimegaprosthetic infection was the leading complication, occurring in 10 (11.5%) patients and implying a megaprosthetic revision in all but one case. Physicians should consider these results when discussing with patients desired outcomes of endoprosthetic reconstructions of a nonneoplastic disease.

Infective complications in tumour endoprostheses implanted after pathological fracture of the limbs

INTRODUCTION

Pathological fractures represent an adverse prognostic factor in primary and metastatic bone tumours. The purpose of this study was to evaluate the results of tumour silver-coated prosthesis implanted after pathological fractures.

MATERIALS AND METHODS

A retrospective analysis was conducted on 30 patients with pathological limb fracture after primary or metastatic bone tumours treated by the same surgeon with wide margin resection and tumour prosthesis implant between 2005 and 2015. Silver-coated prostheses were implanted in 17 patients and uncoated prostheses were implanted in 13 patients. The primary outcome of the study was to evaluate the infective risk, the secondary outcomes were survival and functional level (visual analogue scale [VAS], 36-Item Short Form Health Survey [SF 36], and Musculoskeletal Tumour Society [MSTS] score) obtained at the longest follow-up available. A multivariate analysis was performed considering age, sex, tumour histology, grading and location, resection size, concomitant radiotherapy/chemotherapy, use of mesh for soft tissue reconstruction and local complications (dislocation, relapse, implant breakage). Scanning electron microscopy (SEM) analysis of explanted prosthesis was performed to study the residual silver-coating.

RESULTS

The average age of patients in the study was 56.2 years (range 12-78 years). Silver-coated prostheses were implanted in 56.7% of patients, and uncoated tumour prostheses were used in the remaining 43.3%. The mean follow-up was 40.7 months. A total of 26.7% of patients died at a median time of 28.6 months after surgery. The overall rate of complications was 30%, with 16.7% due to infection. A total of 11.8% of the patients treated with silver-coated implants developed infection compared with 23.1% of the patients treated with uncoated tumour prostheses. There were no cases of early infection in the silver-coated prosthesis group, whereas early infection occurred in 66.7% of patients in the uncoated prosthesis group. All the functional outcomes were significantly improved after surgery. None of the other parameters analysed can be considered a significant negative prognostic factor for infection. The SEM analyses showed severe silver-coating degradation 2 years after first implant. No case of silver toxicity was demonstrated.

DISCUSSION

There are few papers in the literature about infective complications in tumour prosthesis after pathological fracture. Silver-coated implants showed a protective action against early infection. Late infection rate was similar between the groups, thereby indicating a reduction of antimicrobial activity for the silver-coating over time.

CONCLUSIONS

Silver-coated prostheses are a protective factor against early infections in limb salvage surgery after pathological fractures, so may represent the first-choice of implants in this type of surgery.

Limb-salvage treatment of en-block resected distal femoral tumors with endoprosthesis of all-polyethylene tibial component: a 9-year follow-up study

OBJECTIVE

To evaluate the medium-term outcome of limb-salvage surgery using all-polyethylene tibial endoprosthetic replacement following en-block resection for distal femoral tumors.

METHODS

Forty-nine patients with distal femoral tumor were treated between June 2006 and June 2012. The follow-up period was 6-110 months (average 53.4 months). The prosthetic survival was analyzed using the Kaplan-Meier method. The classification of failure of limb salvage after reconstructive surgery for bone tumors was adapted. Limb function was evaluated with the scoring system of the Musculoskeletal Tumor Society (MSTS).

RESULTS

Complications were observed in six cases (12.2%). Four suffered infection around the prosthesis, of which two cases were treated with debridement, drainage, and antibiotics without removal of the prosthesis, and the other two cases underwent amputation. Two cases were identified as radiographically loose at 7 year follow-up and did not require revision surgery. One patient underwent amputation due to local recurrence. Failure of limb salvage occurred in nine cases (18.4%), of which two cases were of type 1A, two cases of type 2B, three cases of type 4A, one case of type 4B, and one case of type 5A. The mean MSTS score was 84.3%. Twelve cases died due to distant metastases (24.5%), and the average survival time for these patients was 13.5 months. Thirty-seven patients survived (75.5%), for whom the average follow-up time was 66.3 months and the 5-year prosthetic survival rate was 88.2%.

CONCLUSION

The outcome of medium-term and long-term clinical follow-up was satisfactory. All-polyethylene tibial endoprosthetic replacement following en-block resection can be an alternative method of limb salvage for distal femoral tumors.

Silver-Coated Hip Megaprosthesis in Oncological Limb Savage Surgery

Silver coating has demonstrated good antimicrobial activity and low toxicity. Silver-coated megaprostheses have been introduced in oncological musculoskeletal surgery considering the high rate of infection. We conducted a retrospective analysis on 68 cases of primary or metastatic bone tumors, affecting the proximal femur, treated between 2005 and 2016 with wide margins resection and tumor implants reconstruction. All patients were treated by the same surgeon, with antibiotic prophylaxis according to a standard protocol. In 55.9% of patients silver-coated hip hemiarthroplasty was implanted; in the remaining 44.1% uncoated megaprostheses were implanted. Patients were reevaluated recording the complications and focusing the analysis on infective complications. The average follow-up was 46.5 months. No patient has shown any sign of local or general silver toxicity. A SEM analysis was conducted on the 3-silver-coated hip hemiarthroplasty explanted confirming a severe degradation with a small amount of residual silver on the coating surface. Silver-coated hip prostheses have a lower rate of early infection than traditional implants but showed a reduction of antimicrobial activity for silver coating wear. We recommend using silver-coated prosthesis as primary implants for limb salvage surgery, in primary or metastatic bone tumors affecting the proximal femur, considering the absence of signs of toxicity and the lower rate of early infection.

Distal femur reconstruction with modular tumour prostheses: a single Institution analysis of implant survival comparing fixed versus rotating hinge knee prostheses

PURPOSE

To evaluate the incidence of complications in distal femur reconstructions with modular prostheses, comparing fixed vs rotating hinge knee.

METHODS

Retrospective analysis of implant survival, complications, and functional results of the Rizzoli series on distal femur megaprosthesis. Between 1983 and 2010, 687 distal femur tumour modular prostheses were implanted: 491 fixed hinge and 196 rotating hinge knee prostheses. Failures of the prostheses were classified in five types: type 1, soft tissue failure; type 2, aseptic loosening; type 3, structural failure; type 4, infection; type 5, tumour progression.

RESULTS

Failure rate was 27 % (185/687). Implant survival to all types of failure was 70 % at ten years and 50 % at 20 years with no significant difference between fixed and rotating hinge knee prostheses (p = 0.0928). When excluding type 5 and type 1 failures, the overall survival was 78 % and 58 % at ten and 20 years. There was not a significant difference in implant survival to aseptic loosening (p = 0.5) and infection (p = 0.2) between fixed and rotating hinge knee prostheses. All cases of breakage of prosthetic components occurred in fixed hinge knee prostheses. Functional results, evaluated in 536 pts, were satisfactory in 91.4 % of cases with a mean score of 23.3 with a significantly better function for rotating hinge knee prostheses (p < 0.001).

CONCLUSIONS

The most frequent cause of failure was infection followed by aseptic loosening. Even if better results were expected for rotating hinge knee prostheses, there is no significant difference in overall implant survival. No cases of breakage of prosthetic components occurred in rotating hinge knee prosthesis. Functional results were significantly better for the rotating hinge knee prostheses.

LEVEL OF EVIDENCE

Therapeutic study, level IV (case series).

Load and failure behavior of human muscle samples in the context of proximal femur replacement

BACKGROUND

To ensure adequate function after orthopedic tumor reconstruction, it is important to reattach the remaining soft tissue to the implant. This study aimed at obtaining mechanical properties of textile muscle-implant and muscle-bone connections in a preliminary test.

METHODS

Two groups of soft-tissue attachment were mechanically tested and compared: Native bone-muscle samples obtained from human femora and muscles attached to a prosthetic implant by means of Trevira® attachment tubes. Additionally, muscle samples were tested with muscle fibers aligned parallel and perpendicular to the tension load. A uniaxial load was exerted upon all samples.

RESULTS

Failure loads of 26.7 ± 8.8 N were observed for the native bone-muscle group and of 18.1 ± 9.9 N for the Trevira® group. Elongations of 94.8 ± 36.2 % were observed for the native bone-muscle group and 79.3 ± 51.8 % for the Trevira® group. The location of failure was mainly observed in the central area of the muscle fibers. Muscle fibers with parallel fiber orientation (47.6 ± 11.5 N) yielded higher tensile strength than those with perpendicular fiber orientation (14.8 ± 4.1 N).

CONCLUSIONS

Our experiments showed that higher forces were transmitted in the origin and insertion areas than in areas of flat soft tissue reconstruction using attachment tubes. The data indicate that the tested material allows reattaching muscles, but without reinforcing the insertion site. Therefore, attachment tubes with region-dependent and potentially anisotropic material behavior might be advantageous to optimize muscle-bone load transmission after surgery, which may allow lower complication rates and shorter physical recovery.

Megaprostheses in the management of trauma of the knee

OBJECTIVE

Review the outcome of patients with complex fractures around the knee treated with megaprosthesis.

METHOD

Retrospective observational study of 10 patients was undertaken.

RESULTS

Six patients were treated with a distal femoral endoprosthesis (DEFPR) and four with an augmented rotating hinge knee replacement (RHK). The mean post-operative Toronto Extremity Salvage Score (TESS) was 62.5 for the whole cohort (RHK group 79.3, compared with 49.2 in the DFEPR group (p = 0.038), peri-prosthetic fracture group was 46.3, compared with 75.6 in native knee fracture group (p = 0.04)).

CONCLUSION

A megaprosthesis is a viable option in complex fractures around the knee.

Management of infection following reconstruction in bone tumors

Limb salvage surgery in bone tumors has evolved in recent years and includes all of the surgical procedures designed to accomplish removal of a malignant tumor and reconstruction of the limb with an acceptable oncologic, functional, and cosmetic result. This dramatic change came about as the result of three important developments, i.e. effective chemotherapy, improved precision imaging techniques and advances in reconstructive surgery. Reconstruction with a modular custom-made oncological endoprosthesis (megaprosthesis) has become a common procedure nowadays. These large foreign bodies make infection a common and feared complication. However, the occurrence of complications may be multifactorial, including a poor nutritional and compromised immune status due to chemotherapy and/or radiotherapy, a lengthy operation, extensive dissection and resection of soft tissues, inadequate soft-tissue coverage, a longer exposure of the wound resulting in infection, etc. Management of postoperative infection in these cases remains a challenge. This article analyses the current literature available for these cases and summarizes the cause and different available methods of treatment.

Fractures in bone tumour prosthesis

PURPOSE

The aim of the present narrative review is to report the different aspects related to the fractures around tumour prosthetic implants in terms of technical and medical issues.

METHODS

A non systematic literature review on the topic was performed.

RESULTS

Given the increased rate of limb salvage procedures and megaprostheses implanted for bone tumours, the increased number of osteoporotic periprosthetic fractures, and the burden of revision arthroplasty, the number of surgeries using endoprosthetic implants is likely to increase in the near future. Surgeons will face more frequently the complications related to tumour endoprosthetic implant. Endoprosthetic reconstruction has a higher risk of intra-operative and post-operative complications compared to conventional prosthetic replacement.

CONCLUSIONS

Very rare reports and recommendations are available in literature regarding the treatment of periprosthetic fractures after megaprosthesis, and there is currently no consensus about which should be the standard management for periprosthetic fractures in this population of patients.

Deep Infections after Endoprosthetic Replacement Operations in Orthopedic Oncology Patients

BACKGROUND

Numerous studies have described various complications after endoprosthetic reconstructive operations. However, there are limited reports that focus specifically on deep infections (e.g., deep incisional surgical site infections), which remain one of the most dreaded complications of these operations, with rates ranging from 10% to 17%. Thus, this study was undertaken to determine the deep infection rates and to analyze possible risk factors, clinico-pathologic characteristics, and treatment modalities of endoprosthetic infections.

METHODS

We reviewed retrospectively the records of 105 consecutive patients who underwent endoprosthesis replacements from January 2007 to September 2011, with a minimal follow-up period of 32 mo. Comparison was made between patients with and without endoprosthetic infections.

RESULTS

Thirteen of the 150 patients (12.38%) who underwent endoprosthetic operations developed deep infections. Ninety-seven (92.4%) patients presented with a primary bone/soft tissue tumor, 5 (4.8%) with bone metastasis, and 3 (2.9%) with non-tumor conditions. Distal femoral was the most common implant location (42%). The majority of the infections (6/13) occurred within 3 mo post-operation. An elevated C-reactive protein concentration or erythrocyte sedimentation rate were present consistently in all patients at time of diagnosis, whereas clinical presentations and leukocytosis were inconsistent in determining infection. Staphylococcus aureus and coagulase-negative staphylococci (CoNS) were the most common organisms isolated, with high numbers demonstrating methicillin-resistance. Overall, multi-drug resistance was noted in 52.6% of the isolated strains. Four risk factors were associated independently with deep infection by multivariable analysis (p<0.05) and these were proximal tibia endoprosthesis, pelvic endoprosthesis, pre-operative duration of hospitalization of more than 48 h, and additional surgical procedures performed after the initial endoprosthetic insertion. Overall, infection was eradicated successfully in 53.8% (7/13) of the patients. Two-stage revision successfully treated the infection in 80% (4/5) of the patients, whereas surgical debridement without a change of implant was successful in only 42.8% (3/7) of patients. Amputation was performed in three patients.

CONCLUSIONS

Patients undergoing endoprosthetic replacement for various orthopedic oncologic conditions have high infection rates. The present study allows early identification of such patients in view of the high morbidity associated with this condition. This report also highlights the high rate of multi-drug-resistant infections, especially methicillin-resistant strains of S. aureus and CoNS encountered, which complicates further the management of these patients.

[Management of complications in megaprostheses]

BACKGROUND

Megaprostheses are frequently used after segmental resection of bone sarcomas, bone metastases, and in large osseous defects in revision arthroplasty.

OBJECTIVES

The incidence of the most common complications associated the use of megaprostheses are reported. The management of complications including therapeutic recommendations are described.

MATERIALS AND METHODS

The current knowledge and our own experience of complication management with the use of megaprostheses are presented.

RESULTS

Prospective, randomized studies or meta-analyses on this topic are lacking. An analysis of the literature shows that beside the occurrence of a local recurrence, periprosthetic infection remains the most serious complication. Two-stage revision remains the gold standard, but a single-stage exchange of the prosthesis without removing the stems might be possible in selected cases. Infection is associated with a higher risk of secondary amputation. In contrast, mechanical failures (e.g., wear of the bushings in knee replacements and aseptic loosening of the stems) can be treated more easily. Dislocation of a proximal femur replacement can mostly be prevented by using bi- or tripolar cups.

CONCLUSIONS

Complications with the use of megaprostheses can be successfully treated by revision surgery in most cases.

Stump lengthening procedure with modular endoprostheses - the better alternative to disarticulations of the hip joint?

We report outcomes of 28 patients after stump-lengthening procedures (SLPs) with modular tumor endoprostheses following high-thigh amputation and hip disarticulation over 11years. Mean follow up was 41.3months (range 7.4 to 133.6months). Mean Musculoskeletal Tumour Society Score was 56% (n=11); ten out of eleven patients alive used an exoprosthesis regularly. Complications occurred in 15 patients with infection being most common. In 2 cases, the prostheses had to be explanted. Our data suggest that SLP facilitates post-operative rehabilitation and prosthesis usage. Modular endoprostheses for stump-lengthening allow optimization of remnant soft-tissue envelope, reducing the risk of stump perforation.

[Tumor prostheses : Important in modern revision arthroplasty]

BACKGROUND

Due to demographic aging, an increasing number of revision arthroplasty procedures is expected during upcoming years. While the use of a megaprosthesis for bone reconstruction after tumor resection is gold standard, this type of prosthesis still meets with reservation in the field of revision arthroplasty because of numerous risk factors.

OBJECTIVES

The purpose of this article is to present the importance of modular megaprostheses in revision arthroplasty, taking into consideration the risks of periprosthetic infection, aseptic loosening, material failure, and hip dislocation.

RESULTS

Because of improvements in the field of megaprostheses during the last 30 years, the risks after implantation of this type of prosthesis have significantly decreased. The risk of periprosthetic infection has been reduced about 1/3 by the use of silver surface coating. Improvements in stem design, cement technique, and the additional use of locking screws have minimized the risk of aseptic loosening. Improvements in material composition have reduced the risk of material failure. The risk of hip dislocation could also be minimized by careful tissue preparation and appropriate suture technique.

CONCLUSION

There is no need for the conservative use of megaprostheses in revision arthroplasty. There are many benefits in the use of megaprostheses in multimorbid patients (i.e., reduced operating time, the possibility of early full weight bearing, and a reduced risk of periprosthetic infection by the use of silver surface coating) instead of complex bone reconstruction during revision arthroplasty.

Survival of modern knee tumor megaprostheses: failures, functional results, and a comparative statistical analysis

BACKGROUND

Modular megaprostheses are now the most common method of reconstruction after segmental resection of the long bones in the lower extremities. Previous studies reported variable outcome and failure rates after knee megaprosthetic reconstructions.

QUESTIONS/PURPOSES

The objectives of this study were to analyze the results of a modular tumor prosthesis after resection of bone tumor around the knee with respect to (1) survivorship; (2) failure rate; (3) comparative survivorship against different sites of reconstructions and of primary and revision implants; and (4) functional results on the Musculoskeletal Tumor Society (MSTS) scoring system.

METHODS

Between 2003 and 2010, 247 rotating-hinge Global Modular Reconstruction System (GMRS) knee prostheses were implanted in our institute for malignant and aggressive benign tumors. During this time, that group represented 23% of the patients who had oncologic megaprosthesis reconstruction about the knee after resection of primary or metastatic bone tumors (247 of 1086 patients). In the other 77% of cases we used other types of oncologic prostheses. Before 2003 we used the older Howmedica Modular Resection System and Kotz Modular Femur/Tibia Replacement from 2003 we used mostly the GMRS but we continued to use the HMRS in some cases such as patients with poor prognoses, elderly patients, or metastatic patients. Sites included 187 distal femurs and 60 proximal tibias. Causes of megaprosthesis failure were classified according to Henderson et al. in five types: Type 1 (soft tissue failure), Type 2 (aseptic loosening), Type 3 (structural failure), Type 4 (infection), and Type 5 (tumor progression). Followup was at a minimum oncologic followup of 2 years (mean, 4 years; range, 2-8 years). Kaplan-Meier actuarial curves of implant survival to major failures were done. Functional results were analyzed according to the MSTS II system; 223 of the 247 were available for functional scoring (81%).

RESULTS

At latest followup, among 175 treated patients for primary reconstruction, 117 are continuously disease-free, 26 have no evidence of disease after treatment of relapse, eight are alive with disease, and 24 died from disease. The overall failure rate of the megaprostheses in our series was 29.1% (72 of 247). Type 1 failure occurred in 8.5% (21 of 247) cases, Type 2 in 5.6% (14 of 247), Type 3 in 0%, Type 4 in 9.3% (23 of 247), and Type 5 in 5.6% (14 of 247). Kaplan-Meier curve showed an overall implant survival rate for all types of failures of 70% at 4 years and 58% at 8 years. Prosthetic survivorship for revisions was 80% at 5 years and for primary reconstructions was 60% at 5 years (p = 0.013). Survivorship to infection was 95% at 5 years for revision patients and 84% at 5 years for primary patients (p = 0.475). The mean MSTS score was 84 (25.2; range, 8-30) with no difference between sites of localization (24.7 in proximal tibia versus 25.4 in distal femur reconstruction; p = 0.306).

CONCLUSIONS

Results at a minimum of 2 years with this modular prosthesis are satisfactory in terms of survivorship (both oncologic and reconstructive) and causes and rates of failure. Although these results seem comparable with other like implants, we will continue to follow this cohort, and we believe that comparative trials among the available megaprosthesis designs are called for.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Limb salvage: When, where, and how?

From an era where amputation was the only option to the current day function preserving resections and complex reconstructions has been a major advance in the treatment of musculoskeletal sarcomas. The objectives of extremity reconstruction after oncologic resection include providing skeletal stability where necessary, adequate wound coverage to allow early subsequent adjuvant therapy, optimising the aesthetic outcome and preservation of functional capability with early return to function. This article highlights the concepts of surgical margins in oncology, discusses the principles governing safe surgical resection in these tumors and summarises the current modalities and recent developments relevant to reconstruction after limb salvage. The rationale of choice of a particular resection modality and the unique challenges of reconstruction in skeletally immature individuals are also discussed. Striking the right balance between adequate resection, while yet retaining or reconstructing tissue for acceptable function and cosmesis is a difficult task. Complications are not uncommon and patients and their families need to be counseled regarding the potential setbacks that may occur in the course of their eventual road to recovery, Limb salvage entails a well orchestrated effort involving various specialties and better outcomes are likely to be achieved with centralization of expertise at regional centers.

Infective complications following tumour endoprosthesis surgery for bone and soft tissue tumours

AIMS

This study aims to describe the incidence of infective complications, including tumour endoprosthesis infection, in a cohort of patients undergoing tumour endoprosthesis surgery in Victoria, Australia.

METHODS

This retrospective cohort study was performed over 15 years (January 1996-December 2010).

RESULTS

121 patients underwent tumour endoprosthesis surgery during the study period. Patients were followed for a median of 34 months (interquartile range [IQR] 17, 80). Overall, 34 patients (28%) experienced infective complications including: bacteraemia in 19 patients (16%) and tumour endoprosthesis infection in 17 (14%). The majority of patients with early and late acute infections (haematogenous) were managed with debridement and retention of the prosthesis in addition to biofilm-active antibiotics. Late chronic infections were predominantly managed by exchange of the prosthesis. The overall success rate of treatment was 71%. The success rate for debridement and retention was 75% compared with 67% for exchange procedures.

CONCLUSIONS

There is a significant rate of infective complications following tumour endoprosthesis surgery including 14% of patients experiencing infection involving the tumour endoprosthesis. This study is the first to report on outcomes from debridement and retention of the prosthesis; which had comparable success rates to other treatment modalities.

[Management of complications following resection and defect reconstruction of tumors near the hip joint]

BACKGROUND

Tumorous destruction of the periacetabular region and the proximal femur are a consequence of either primary malignant bone tumor manifestation or metastatic disease, which is observed much more frequently and occurs typically in these skeletal segments. Pathological fractures of the proximal femur and periacetabular regions of the pelvis have a high incidence and ultimately lead to severe pain and immobilization.

TREATMENT METHODS

Advanced resection techniques and different types of defect reconstruction, allowing for oncologically sufficient resection of extensive tumors have contributed to a marked increase in the limb salvage rate. However, these procedures are associated with an increasing rate of several, sometimes severe intraoperative and postoperative complications.

COMPLICATIONS

Compared to elective total hip arthroplasty, the rate of postoperative deep infections, dislocations, the incidence of pathological and periprosthetic fractures and the prevalence of deep vein thrombosis are increased with high rates of postoperative mortality and local tumor recurrence, being the most serious complications. Pelvic involvement and subsequent periacetabular resection have the highest complication rate when compared to proximal femur resection with endoprosthetic treatment.

CONCLUSION

In order to minimize the risk of these intraoperative and postoperative complications wide resection and advanced reconstruction as well as complicated palliative stabilization due to malignant bone tumor growth around the hip joint should be performed in musculoskeletal tumor centers with profound expertise in osteosynthetic and endoprosthetic reconstruction of the pelvis and the proximal femur. Only in specialized centers an effective, multidisciplinary emergency management of these complications and, more importantly, reliable prevention of complications can be ensured.

Clinical outcomes of Kyocera Modular Limb Salvage system after resection of bone sarcoma of the distal part of the femur: the Japanese Musculoskeletal Oncology Group study

PURPOSE

The Japanese Musculoskeletal Oncology Group have developed an original prosthesis called the Kyocera Modular Limb Salvage system (KMLS system). This prosthesis has a semi-rotating hinge joint and is particularly designed for people with an Asian body type. The metallic parts of the prosthesis are made entirely of titanium alloy. The purpose of this study is to evaluate the clinical outcomes of treatment using this system following tumour resection of primary bone sarcoma of the distal femur.

METHODS

Between 2002 and 2010, 82 patients with primary bone sarcomas of the distal femur were treated. Seventeen patients underwent stem cementation, while 65 patients were treated with cementless prostheses. The mean follow-up period after surgery was 61 months.

RESULTS

Complications were observed in 28 of the 82 patients. Forty-one complications occurred in these 28 patients. Thirteen prostheses (16%) required revision surgery due to complications, including five cases of stem breakage, three deep infections, three cases of aseptic loosening, one case of displacement of the shaft cap and one case of breakage of the tibial tray. The five-year overall prosthetic survival rate was 80.0%. Four of the 82 patients underwent subsequent amputation due to local recurrence. The five-year limb salvage rate was 94.5%. The mean function score according to the scoring system of the Musculoskeletal Tumour Society was 21.8 points (72.5%).

CONCLUSIONS

Although further follow-up is required to determine the performance, this prosthesis is considered to be satisfactory for reconstruction of the distal femur after resection of bone sarcoma.

Treatment solutions are unclear for perimegaprosthetic infections

BACKGROUND

Infection about a megaprosthesis is a dreaded complication. Treatment options vary from débridement alone to staged revisions, arthrodesis, and amputation. Indications for how to treat this complication are unclear.

QUESTIONS/PURPOSES

We therefore determined (1) the incidence of perimegaprosthetic infections, (2) the methods of treatment, (3) the number of patients who failed their original treatment plan, and (4) the characteristics of the infection.

METHODS

We retrospectively identified 291 patients who had megaprostheses implanted between 2001 and 2011 and identified all those surgically treated for a perimegaprosthetic infection during that time. We defined a treatment failure as any unplanned reoperation or death due to uncontrolled infection. All patients with failure had a minimum followup of 1 year (mean, 3.3 years; range, 1-8 years).

RESULTS

Of the 291 patients, 31 (11%) had subsequent infections. Surgical management varied among irrigation and débridement (n=15), single-stage revisions (n=11), two-stage revisions (n=4), and amputations (n=1). Sixteen patients failed their original treatment plan: 13 required additional surgery and three died. Infections were mostly chronic and single organism with five being methicillin-resistant Staphylococcus aureus.

CONCLUSIONS

An 11% incidence of perimegaprosthetic infections is consistent with the increased risk of infection seen in other studies. A variety of surgical methods were employed at our institution and by those contributing to the literature without clear evidence of superiority of one method over another. Given the complicated medical and surgical histories of these patients, individualization in decision making is necessary.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

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).

Functional analysis of cases of tumor endoprostheses with deep infection around the knee: a multi institutional study by the Japanese Musculoskeletal Oncology Group (JMOG)

BACKGROUND

Although intensive studies have been conducted to clarify the incidence, risks, and management methods of deep infection of tumor endoprostheses, limited data have been published in respect of the impact of such deep infection on the function of the corresponding limb.

METHODS

Clinical data of 125 patients (infection group 57, control group 68) with malignant bone and soft tissue tumors around the knee enrolled with the Japanese Musculoskeletal Oncology Group were collected. We analyzed the impact of deep infection of tumor endoprostheses on the limb salvage status together with that on the function of the salvaged limb. The definition of deep infection was based on the recommendations of the Centers for Disease Control and Prevention. The functional evaluation was based on the functional classification system established by the International Society of Limb Salvage and the Musculoskeletal Tumor Society.

RESULTS

Infection together with extracapsular resection was demonstrated to be a risk factor for late amputation. There were no significant differences in the functional scores for "pain," "support," "walking," or "gait" between the infection and control groups. The risk factors identified for a loss of score for "functional activities" were deep infection, age, duration of operation, and extracapsular resection. The infection group also showed a significant lower score loss in "emotion". As for the overall functional scores, the risk factors identified for lower scores were deep infection and age. The mean scores for the infection group and control group were 19.3 (64.3 %) and 21.6 (72 %), respectively. Although the difference was confirmed to be statistically significant, the actual difference was only 2.3 (10.6 % reduction).

CONCLUSIONS

Infection was a major risk factor for late amputation. Limbs salvaged by management of deep infection may show loss of function; however, the impact may be limited.

Febrile response following megaprosthesis replacement for primary bone sarcoma

The presence of early postoperative fever after megaprosthesis replacement surgery is a concern for orthopedic oncologists due to the possibility of infection. The aims of the current study were to determine the incidences and patterns of fever and factors associated with its development and to determine the clinical significance of fever after megaprosthesis replacement surgery. Seventy-one patients who had undergone megaprosthesis reconstruction for previously unoperated localized lower-extremity osteosarcoma were reviewed. No patient had evidence of infection preoperatively. Mean patient age was 23.72±16.84 years (range, 6.7-74 years), and average follow-up was 59.5 months (range, 4-240 months). Five postoperative surgical wound infections (4 deep, 1 superficial) occurred on postoperative days 5, 13, 14, 20, and 21. Fevers (body temperature of 38 °C or higher) were present in 62 patients (87.3%) at some point during the first 2 postoperative weeks. Peak body temperature was observed on postoperative day 1 in 62% of the febrile patients. Of the 62 febrile patients, 94% were relieved of fever by postoperative day 5. No significant association was observed between the presence of fever and surgical wound infection. Body temperature curves in patients with infection showed that several atypical patterns, such as multiple fever peaks and persistent fever, were accompanied by physical findings within the normalization period. Fever during the first 5 postoperative days is common after megaprosthesis replacement for bone sarcomas and seems to be a normal physiologic response to surgery. However, atypical fever patterns or additional physical findings require investigation.

Measurement of the silver ion concentration in wound fluids after implantation of silver-coated megaprostheses: correlation with the clinical outcome

Background. Tumor patients and patients after traumas are endangered by a reduced immune defense, and a silver coating on their megaprostheses may reduce their risks of infection. The aim of this study was to determine the silver ion concentration directly measured from the periprosthetic tissue and the influence on the clinical outcome. Material and Methods. Silver ions were evaluated in 5 mL wound fluids two days postoperatively and in blood patients 7 and 14 days after surgery using inductively coupled plasma emission spectrometry in 18 patients who underwent total joint replacement with a silver-coated megaendoprosthesis. Results. The concentration of silver ions averaged 0.08 parts per million. Patients who showed an increased silver concentration in the blood postoperatively presented a lower silver concentration in the wound fluids and a delayed decrease in C-reactive protein levels. There were significantly fewer reinfections and shorter hospitalization in comparison with a group that did not receive a silver-coated megaprosthesis. Conclusion. An increased concentration of silver in the immediate surroundings of silver-coated prostheses was demonstrated for the first time in cohorts of patients with trauma or tumors. An elevated concentration of silver ions in the direct periprosthetic tissue may have reduced the infection rate.

Deep infection in tumor endoprosthesis around the knee: a multi-institutional study by the Japanese musculoskeletal oncology group

Background

The incidence of endoprosthesis failure has been well studied, but few studies have described the clinical characteristics of deep infection in tumor prostheses. This study aimed to analyze the characteristics of deep infection in tumor endoprostheses around the knee.

Methods

We analyzed clinical data of 57 patients with deep infections involving tumor endoprostheses around the knee enrolled from the Japanese Musculoskeletal Oncology Group. Profile of clinical presentation including time between surgery and infection, initial symptoms/blood tests and microbial cultures was evaluated. In addition pre-, intra-, and postoperative clinical factors influencing clinical presentation and treatment outcomes of infections were analyzed.

Results

Mean interval between the initial operation and diagnosis was 13 months, and mean time required for infection control was 12 months. The most common pathogen was Staphylococcus. Infection control rates were significantly higher when prostheses were removed rather than salvaged. Ten-year prosthesis survival and limb salvage rates were 41.6% and 75.6%, respectively. Analysis of underlying clinical factors suggested that soft-tissue condition significantly influenced the duration of the infection control period and likelihood of limb salvage.

Conclusions

Infection control is a prolonged process. Deep infection frequently results in amputation or prosthesis loss. Intensive analysis of clinical characteristics may aid infection control.

Distal femur and proximal tibia replacement with megaprosthesis in revision knee arthroplasty: a limb-saving procedure

PURPOSE

The aim of the present study was to assess whether using megaprostheses in revision knee arthroplasty procedures allows limb salvage with an acceptable outcome and complication rate, in comparison with other limb-saving procedures.

METHODS

Between 2000 and 2010, megaprosthesis implantation was required for non-oncologic indications in 20 patients (21 knees) (average age 73 years). Reconstructions involved the distal femur (n = 15), proximal tibia (n = 4), and both femur and tibia (n = 2). The indications, type, and numbers of previous operations and implants, as well as complications associated with megaprosthesis implantation, were reviewed, and the clinical and radiographic outcomes after an average follow-up period of 34 months (range 10-84 months) were evaluated.

RESULTS

The indications for megaprosthesis implantation were periprosthetic infection (n = 5), fracture (n = 9), nonunion (n = 5), and aseptic loosening (n = 2). The types of implant placed before the megaprosthetic reconstruction were a cemented rotating-hinge arthroplasty (n = 16) and a primary total knee arthroplasty (n = 5). Six patients had an additional osteosynthesis of the distal femur. An average of 3.8 operations (range 1-7) had been carried out before megaprosthesis implantation. Complications developed in 11 patients. The Knee Society Score improved significantly, from 43 (± 15) to 68 (± 16.8); P < 0.05.

CONCLUSIONS

Megaprosthesis implantation in revision knee arthroplasty is an exceptional indication. Despite the high complication rate, the patients can be spared amputation in most cases, and rapid mobilization with full weight-bearing is possible.

Long term results of fixed-hinge megaprostheses in limb salvage for malignancy

We retrospectively studied the files of 669 patients with musculoskeletal tumors treated with limb salvage and reconstruction using fixed-hinge knee megaprostheses. We used the KMFTR® prosthesis from 1983 to 1989 in 126 patients, and the HMRS® prosthesis thereafter in 543 patients because of the anatomical femoral stem with one lateral flange for improved stress-shielding, the new hinge design and new generation polyethylene placed centrally in the metallic hinge, and the improved function compared to the former prosthesis. Distal femoral reconstructions were done in 474, proximal tibia in 163, extrarticular knee joint in nine, and total femoral in 23 patients. At 10 and 20 years follow-up, survival to breakage was 95% and 85%, to aseptic loosening 94% and 82%, to infection 90% and 82%, and to polyethylene wear 95% and 37%. A statistically significant higher survival to breakage of the HMRS® prostheses was observed. No statistical difference of survival to breakage regarding the site of reconstruction, aseptic loosening, infection, polyethylene wear and mean functional score between the two types of prostheses was observed.

Surgical site infection in malignant soft tissue tumors

BACKGROUND

Postoperative wound complications, including surgical site infections, which frequently occur in the course of management of musculoskeletal sarcomas, sometimes necessitate repeat surgeries, including amputation, and may result in a prolonged healing time, prolonged hospital stay, or fatal outcome. A comprehensive understanding of surgical site infections associated with specific diseases is needed to reduce the risk.

METHODS

This series comprised 84 patients with malignant soft tissue tumors treated at our institute. The occurrence rate, management modality and clinical course of surgical site infections, impact of surgical site infections on the length of hospitalization, risk factors for the development of surgical site infections, and the impact of surgical site infections on the oncological outcomes were analyzed. Surgical site infection was defined according to Centers for Disease Control and Prevention guidelines.

RESULTS

Surgical site infections occurred in 7 cases (8.3%). Although successful clinical cure was achieved in all cases, surgical site infection was identified as one of the independent risk factors for prolongation of hospitalization. Both univariate and multivariate analyses identified larger intraoperative blood loss and a trunk location as risk factors associated with deep infections. No association was detected between age, tumor grade, chemotherapy, tumor volume, or plastic surgery and the risk of surgical site infections. Although the differences were not statistically significant, patients with surgical site infections showed worse oncological outcomes in terms of local recurrence and total survival.

CONCLUSION

The incidence rate of surgical site infection was larger than that associated with conventional orthopedic surgeries, such as osteosynthesis, spine surgery, or arthroplasty. Surgical site infections remain a critical and frequent complication of surgical treatment of soft-tissue malignancies and often result in prolongation of hospital stay. Although practical options to prevent surgical site infections seem quite limited, the present data provide a rationale for perioperative evaluation in patients at a high risk of surgical site infections.

Prophylactic antibiotic regimens in tumour surgery (PARITY): protocol for a multicentre randomised controlled study

INTRODUCTION

Limb salvage with endoprosthetic reconstruction is the standard of care for the management of lower-extremity bone tumours in skeletally mature patients. The risk of deep postoperative infection in these procedures is high and the outcomes can be devastating. The most effective prophylactic antibiotic regimen remains unknown, and current clinical practice is highly varied. This trial will evaluate the effect of varying postoperative prophylactic antibiotic regimens on the incidence of deep infection following surgical excision and endoprosthetic reconstruction of lower-extremity bone tumours.

METHODS AND ANALYSIS

This is a multicentre, blinded, randomised controlled trial, using a parallel two-arm design. 920 patients 15 years of age or older from 12 tertiary care centres across Canada and the USA who are undergoing surgical excision and endoprosthetic reconstruction of a primary bone tumour will receive either short (24 h) or long (5 days) duration postoperative antibiotics. Exclusion criteria include prior surgery or infection within the planned operative field, known colonisation with methicillin-resistant Staphylococcus aureus or vancomycin-resistant Enterococcus at enrolment, or allergy to the study antibiotics. The primary outcome will be rates of deep postoperative infections in each arm. Secondary outcomes will include type and frequency of antibiotic-related adverse events, patient functional outcomes and quality-of-life scores, reoperation and mortality. Randomisation will be blocked, with block sizes known only to the methods centre responsible for randomisation, and stratified by location of tumour and study centre. Patients, care givers and a Central Adjudication Committee will be blinded to treatment allocation. The analysis to compare groups will be performed using Cox regression and log-rank tests to compare survival functions at α=0.05.

ETHICS AND DISSEMINATION

This study has ethics approval from the McMaster University/Hamilton Health Sciences Research Ethics Board (REB# 12-009). Successful completion will significantly impact on clinical practice and enhance patients' lives. More broadly, this trial will develop a network of collaboration from which further high-quality trials in Orthopaedic Oncology will follow.

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.

Infected total femoral replacements: evaluation of limb loss risk factors

A complication of total femoral replacement (TFR) is periprosthetic infection. Studies have shown that infected endoprostheses have a significant amputation rate, as high as 36.7%. This study examined possible risk factors that may attribute to unsalvageable TFRs following periprosthetic infections, including age, sex, primary vs secondary TFRs, number of irrigation and debridements, recent history of periprosthetic infection, early vs late infection, use of antibiotic cement, and the number of postoperative antibiotics. In a retrospective chart review, 10 patients who had periprosthetic infections of their TFRs were identified from our orthopedic surgical database between 2000 and 2010. Seven of 10 TFRs were unsalvageable due to infection. The 2 greatest risk factors that influenced unsalvageable TFR were age older than 50 years and recipients of secondary TFRs. All 6 patients older than 50 years had unsalvageable TFRs, whereas 1 of 4 patients younger than 50 years had an unsalvageable TFR (P<.05). Similarly, all 6 patients who received secondary TFRs had unsalvageable TFRs, whereas 1 of 4 patients who received a TFR as the primary method of treatment had an unsalvageable TFR (P<.05). No other risk factors showed statistical significance or could be identified as possible risk factors. Surgeons should educate patients who fall into high-risk categories about the benefits of early intervention, such as amputation, that could prevent additional surgeries and decrease the lengths of hospitalizations.

Perioperative infection rate in patients with osteosarcomas treated with resection and prosthetic reconstruction

BACKGROUND

The incidence of perioperative infection after segmental tumor endoprosthetic replacement in previous reports varies from a high of 7.4% to a low of 2.6%. Appropriate antibiotic use for this group is unknown and controversial, whereas the relationship of antibiotic use and perioperative infection is unclear.

QUESTIONS/PURPOSES

We determined the incidence of perioperative infection in patients with osteosarcoma treated with segmental prosthetic replacement using a standard perioperative antibiotic regimen and the incidence of late infections and wound complications.

PATIENTS AND METHODS

We retrospectively reviewed the records of 53 patients with osteosarcoma undergoing segmental prosthetic replacements from 1993 to 2008. There were 30 males and 23 females ranging from 10 to 78 years of age. All patients were given intraoperative antibiotics (intravenous cefazolin), continued for 3 days postoperatively and then given orally for 5 days. Patients who were allergic to penicillin or cefazolin were given vancomycin followed by clindamycin. A perioperative infection was defined as a deep infection within 2 months after prosthetic reconstruction. The minimum followup was 1 year (range, 1-15 years).

RESULTS

We identified one confirmed perioperative prosthetic infection (1/53; 1.9%) (Enterobacter cloacae and methicillin-resistant Staphylococcus) in a 78-year-old woman after proximal tibial replacement, gastrocnemius flap, and skin graft. Her infection was controlled with débridement, drainage, and intravenous antibiotics. Three patients had late infections, two of which were culture negative. Four patients had wound complications that required further surgery.

CONCLUSION

The antibiotic regimen we used is longer than that recommended for patients having routine total joint arthroplasty. Its appropriateness will require comparison with alternate regimens, including those of shorter duration.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Modified vertical rectus abdominis musculocutaneous flap for limb salvage procedures in proximal lower limb musculoskeletal sarcomas

Introduction and aim. Management of complicated wounds after tumor extipiration of pelvic and proximal lower limb musculoskeletal sarcoma represents an essential component in the outcome of these patients. The authors present modified vertical rectus abdominis musculocutaneous (VRAM) flap techniques to reconstruct extensive defects after debridment of these complicated wounds. Material and Methods. Over a period of 4 years (2002–2005), 5 men and 2 women were managed. Median age was 21 years (range 15–49). The patients were managed for complicated lower trunk, groin, and upper thigh wounds after resection of three pelvic chondrosarcomas as well as two pelvic and two proximal femur osteosarcomas. The modifications included a VRAM flap with lateral and tongue-like extension design of the skin paddle (5 cases) or a delayed extended VRAM flap (2 cases). Results. All flaps showed complete survival and healing with no ischemic events providing stable coverage. All patients were ambulant with good limb functions in terms of walking and gait after adequate rehabilitation, 2 needed support with crutches. Conclusion. The modified VRAM flaps offer reliable reconstructive tools for coverage of complex groin and thigh defects by providing larger well-vascularized soft tissue with acceptable donor site.

Pasteurized autograft-prosthesis composite for proximal femoral reconstruction: an alternative to allograft composite

BACKGROUND

Allograft-prosthesis composite (APC) for proximal femur reconstruction have shown favorable longevity and functional outcome compared to endoprosthesis, owing to restoration of bone stock, load-sharing property, and biological attachment of abductors and iliopsoas tendons.

QUESTIONS/PURPOSES

This study examined whether a pasteurized-prosthesis composite (PPC) is comparable to APC regarding implant survival, functional outcome, and complication rates.

PATIENTS AND METHODS

We retrospectively reviewed 18 patients with proximal femur malignancy that underwent reconstruction with a cemented pasteurized autograft-prosthesis composite between 1993 and 2008. We evaluated implant survival (Kaplan-Meier), functional outcome (MSTS score), complications and secondary operations.

RESULTS

The estimated survival rate of the 18 composites was 86% at 5 and 10 years. Within a mean follow-up of 93 months (median 113, range 14-163) two composites (11%) were removed due to un-resolving infection. The mean MSTS functional score of surviving 16 composites was 80% (range 70-95). Non-union and stem loosening in host bone were identified in a single patient, while infection developed in two patients. THA conversion occurred in three composites due to secondary osteoarthritis in two, and subluxation in one case. Two of the six cases, with greater trochanter (GT) reconstruction, showed GT avulsion. No autograft was fractured.

CONCLUSIONS

Pasteurized autograft-prosthesis composite (PPC) of the proximal femur has comparable survival rate, functional outcome, and complication rates to allograft-prosthesis composite (APC), thereby offering an alternative reconstructive option for proximal femoral reconstruction.

Cemented endoprosthetic reconstruction of the proximal tibia: how long do they last?

BACKGROUND

The few available studies documenting the long-term survival of cemented proximal tibial endoprostheses for musculoskeletal tumors do not differentiate between stem designs or patient diagnosis. There is wide variation in survival rates reported, possibly a result of this heterogeneity in patient population and implant design.

QUESTIONS/PURPOSES

We therefore asked: (1) How long do proximal tibial endoprostheses last? (2) What is the typical long-term functional result after proximal tibial replacement? And (3) what are the short- and long-term complications associated with endoprosthetic reconstruction of the proximal tibia, particularly with respect to the soft tissue reconstruction?

PATIENTS AND METHODS

We retrospectively reviewed 52 patients with 52 proximal tibial endoprosthetic reconstructions for a tumor-related diagnosis. Kaplan-Meier survivorship analysis was performed using revision of the stemmed components for any reason as an endpoint for implants, and death due to disease progression for patients. Function was assessed using the MSTS scoring system. The minimum followup was 1 month (mean, 96 months: range, 1-284 months; median, 69 months).

RESULTS

Using revision of the stemmed components for any reason as an end point, overall prosthesis survival at 5, 10, 15, and 20 years was 94%, 86%, 66%, and 37%, respectively. The 29 modular implants demonstrated a trend toward improved survival compared to the 23 custom-designed components, with a 15-year survivorship of 88% versus 63%. The mean postoperative Musculoskeletal Tumor Society score at most recent followup was 82% of normal function (mean raw score, 24.6; range, 4-29).

CONCLUSIONS

Cemented endoprosthetic reconstruction of the proximal tibia provides a reliable method of reconstruction following tumor resection.