Salvaging the limb salvage: management of complications following endoprosthetic reconstruction for tumours around the knee

Osseointegration reduces aseptic loosening of primary distal femoral implants in pediatric and adolescent osteosarcoma patients: a retrospective clinical and radiographic study

AIM

The challenge of distal femoral replacement (DFR) longevity remains a priority for orthopaedic oncologists as the overall survival and activity level of young patients with osteosarcoma continues to improve. This study hypothesized that increased extracortical osseointegration at the bone-implant shoulder (i.e., where the metal implant shaft abuts the femur) will improve stress transfer adjacent to the implant, as evidenced by reduced cortical bone loss, radiolucent line progression and implant failure in young patients (< 20 years) following DFR surgery.

METHODS

Twenty-nine patients of mean age 13.09 ± 0.56 years received a primary DFR. The clinical outcome of 11 CPS®, 10 GMRS®, 5 Stanmore® and 3 Repiphysis® implants was evaluated over a mean follow-up period of 4.25 ± 0.55 years. The osseous response to a bone-implant shoulder composed of either a hydroxyapatite-coated grooved ingrowth collar (Stanmore®), a porous metal coating (GMRS®) or a polished metal surface (Repiphysis®) was quantified radiographically.

RESULTS

All (100.0%) of the Stanmore® implants, 90.0% of GMRS®, 81.8% of CPS® and 33.3% of the Repiphysis® implants survived. Significantly increased extracortical bone and osseointegration were measured adjacent to the Stanmore® bone-implant shoulder when compared with the GMRS® and Repiphysis® implants (p < 0.0001 in both cases). Significantly decreased cortical loss was identified in the Stanmore® group (p = 0.005, GMRS® and p < 0.0001, Repiphysis®) and at 3 years, the progression of radiolucent lines adjacent to the intramedullarly stem was reduced when compared with the GMRS® and Repiphysis® implants (p = 0.012 and 0.026, respectively).

CONCLUSIONS

Implants designed to augment osseointegration at the bone-implant shoulder may be critical in reducing short- (≤ 2 years) to mid- (≤ 5 years) term aseptic loosening in this vulnerable DFR patient group. Further longer-term studies are required to confirm these preliminary findings.

Accuracy of MRI scans in predicting intra-articular joint involvement in high-grade sarcomas around the knee

Aims

Intra-articular (IA) tumours around the knee are treated with extra-articular (EA) resection, which is associated with poor functional outcomes. We aim to evaluate the accuracy of MRI in predicting IA involvement around the knee.

Methods

We identified 63 cases of high-grade sarcomas in or around the distal femur that underwent an EA resection from a prospectively maintained database (January 1996 to April 2020). Suspicion of IA disease was noted in 52 cases, six had IA pathological fracture, two had an effusion, two had prior surgical intervention (curettage/IA intervention), and one had an osseous metastasis in the proximal tibia. To ascertain validity, two musculoskeletal radiologists (R1, R2) reviewed the preoperative imaging (MRI) of 63 consecutive cases on two occasions six weeks apart. The radiological criteria for IA disease comprised evidence of tumour extension within the suprapatellar pouch, intercondylar notch, extension along medial/lateral retinaculum, and presence of IA fracture. The radiological predictions were then confirmed with the final histopathology of the resected specimens.

Results

The resection histology revealed 23 cases (36.5%) showing IA disease involvement compared with 40 cases without (62%). The intraobserver variability of R1 was 0.85 (p < 0.001) compared to R2 with κ = 0.21 (p = 0.007). The interobserver variability was κ = 0.264 (p = 0.003). Knee effusion was found to be the most sensitive indicator of IA involvement, with a sensitivity of 91.3% but specificity of only 35%. However, when combined with a pathological fracture, this rose to 97.5% and 100% when disease was visible in Hoffa's fat pad.

Conclusion

MRI imaging can sometimes overestimate IA joint involvement and needs to be correlated with clinical signs. In the light of our findings, we would recommend EA resections when imaging shows effusion combined with either disease in Hoffa's fat pad or retinaculum, or pathological fractures.

Cemented vs uncemented megaprostheses in proximal femur metastases: a multicentric comparative study

BACKGROUND

Hip megaprostheses are a long known reconstructive method in the treatment of proximal femur metastases. The use of cemented or uncemented stems is still matter of debate. The aim of this study to compare cemented and uncemented megaprostheses on functional outcomes and complications, in order to establish the role of cementation.

METHODS

We retrospectively analysed 51 metastatic patients with proximal femur metastases treated with endoprosthetic reconstruction by megaprostheses, 25 with cementless stems and 26 with cemented ones with different megaprosthetic implants. The primary endpoint was MSTS score, and the secondary endpoint was to state the incidence of surgical and clinical complications in the two groups. An un-paired T test was used to compare anthropometric, anamnestic data, and MSTS. Chi-square test was performed for evaluation of complication in the two group. Multiple linear regression was used to match the functional outcomes and complications' incidence in the population study. Logistic regression was performed to analyse the odds ratio of different parameters and their role in the incidence of complications.

RESULTS

The mean follow-up was 50.1 months (+ 12.5). In thirty case right side was involved. No statistical differences were noticed between Group A and B regard the age, gender, active fracture/impending fracture. Comparing the MSTS results within the two groups at last follow-up, the score cemented group was higher than cementless one (17.9 + 7.8 vs 24.2 + 5.3; statistical significance p = 0.001). Regarding surgical complications a logistic regression was performed to analyse the odds ratio of age, cementation and length of resection; cementation confirm and odds ratio of 11 times in the incidence of surgical complications.

CONCLUSIONS

Cementation seems to be more liable to complications onset, while improves functional score in metastatic patients compared to uncemented megaprostheses. More studies have to be conducted in order to create a protocol and establish criteria to use cemented or uncemented stems in a frail population like metastatic patients.

Management of sarcoma recurrence after megaprosthesis of the knee

BACKGROUND

The management of local sarcoma recurrence about the knee (at the distal femur or proximal tibia) is challenging. The objective of this study was to describe the locations of local sarcoma recurrences about knee megaprostheses, the treatments used for each type of recurrence, and the outcomes according to the treatment used.

HYPOTHESIS

The strategy for treating a local sarcoma recurrence about the knee must be based on the topography of tumour involvement.

MATERIALS AND METHODS

We included 13 patients who had local sarcoma recurrence about a knee megaprosthesis and were followed up for at least 2 years. The diagnosis was osteosarcoma in 10 patients and chondrosarcoma in 3 patients. The distal femur was involved in 11 patients and the proximal tibia in 2 patients. We classified the patients into two groups based on whether the tumour involved important structures or was at a distance within the soft tissues.

RESULTS

The recurrence was a nodule at a distance of important structures in 8 (57%) patients, in whom the mean time to recurrence was 15 months (range, 2-34 months). The remaining 5 (38.5%) patients had involvement of important structures in the popliteal fossa and a mean time to recurrence of 42 months (range, 16-80 months). Surgery was performed in 10 patients; the other 3 patients received palliative care due to rapid metastatic dissemination. Of the 6 patients who had surgery for a recurrence at a distance from important structures, 5 (83.3%) underwent isolated tumour resection with the goal of salvaging the limb and 1 (16.7%) underwent transfemoral amputation. Transfemoral amputation was performed in all 3 patients who had surgery for popliteal recurrences. Lung metastases were detected in 10 (77%) patients, 2 at the time of initial sarcoma diagnosis and 8 at the time of the local recurrence. At last follow-up, 5 patients were alive, including 2 (33.3%) of the 6 patients with recurrences at a distance from important structures and all 3 patients with popliteal recurrences. Of the 5 survivors at last follow-up, 2 had metastases.

CONCLUSION

In patients with local recurrence of knee sarcoma, three presentations can be distinguished. When the local recurrence coincides with distant recurrence, failure to control the disease is likely and the local treatment should be designed as a component of palliative care. When no metastases are detected but the local recurrence is in contact with important structures, amputation is advisable at present given the complexity of limb-salvage surgery and high risk of further local recurrence. Finally, when no metastases are detected and the local recurrence is at a distance from important structures, limb-salvage surgery deserves consideration.

LEVEL OF EVIDENCE

IV, retrospective observational study.

Patellar dislocation following distal femoral replacement after extra-articular knee resection for bone sarcoma: A case report

BACKGROUND

For the treatment of bone sarcoma in the distal femur, wide-margin resection and knee reconstruction with tumor endoprosthesis are standard therapies. Extra-articular knee resection is required in cases of tumor invasion of the knee joint; however, the incidence of complications, such as aseptic loosening, prosthesis infection, and implant failure, is higher than that following intra-articular knee resection. To the best of our knowledge, there are three reports of patellar dislocations after replacement of a tumor endoprosthesis.

CASE SUMMARY

A 36-year-old man with no significant past medical history was admitted to our institution with continuous pain in his left knee for 4 mo. An open biopsy was performed, and the patient was diagnosed with a left distal femoral malignant bone tumor. Extra-articular knee resection and knee reconstruction with a tumor endoprosthesis were performed. Although the alignment of the tumor prosthesis was acceptable, knee instability was noticed postoperatively. The axial radiographic view of the patellar and computed tomography showed lateral patellar dislocation at 4 wk postoperatively. The patient had to undergo a lateral release and proximal realignment. He could perform his daily activities at 9 mo postoperatively. Radiography revealed no patellar re-dislocation.

CONCLUSION

Proximal realignment may be considered during primary surgery if there is an imbalance in the forces controlling the patellar tracking.

Long-Term Results of Kyocera Modular Limb Salvage System after Resection of Tumors in the Distal Part of the Femur: Report from Japanese Musculoskeletal Oncology Group Study

Simple Summary

We aimed to elucidate the long-term outcomes of a distal femur reconstruction system in 125 patients with bone and soft tissue tumors. Implant survival rates at 10 and 15 years were 58.5% and 39.4%. Stem breakage should be considered in patients with cementless and/or smaller femoral stem sizes. Aseptic loosening should be considered in patients with a cement system after 10 years.

Abstract

Background: The distal femur is a common site of bone tumors. After surgical resection, prosthetic replacement is a major reconstruction method. We aimed to elucidate the long-term outcomes of the Kyocera Modular Limb Salvage (KMLS) systems after resection of tumors in the distal part of the femur. Methods: Between 1998 and 2014, 125 patients were treated at 14 institutions. There were 59 males and 66 females, with a mean age of 35 years. The mean follow-up period was 132 months. Results: There had been 65 additional surgeries, including 56 revisions and 9 amputations: 15 for aseptic loosening, 14 for stem breakage, 13 for deep infection, 13 for rotator-hinge bushing failure, 5 for local recurrence, and 5 for others. Implant survival rates at 10 and 15 years were 58.5% and 39.4%. The cumulative incidence of 15-year revision for femoral stem breakage was 31.7% in patients with cementless fixation. The 15-year cumulative incidence of revision for aseptic loosening was 19.8% in patients with cement fixation. Conclusions: KMLS systems represent a reliable system with long-term results. Stem breakage should be considered in patients with cementless and/or smaller femoral stem sizes. Aseptic loosening should be considered in patients with cement systems after 10 years.

Ferumoxytol magnetic resonance imaging detects joint and pleural infiltration of bone sarcomas in pediatric and young adult patients

BACKGROUND

The diagnosis of joint infiltration by a malignant bone tumor affects surgical management. The specificity of standard magnetic resonance imaging (MRI) for diagnosing joint infiltration is limited. During our MRI evaluations with ferumoxytol nanoparticles of pediatric and young adult patients with bone sarcomas, we observed a surprising marked T1 enhancement of joint and pleural effusions in some patients but not in others.

OBJECTIVE

To evaluate if nanoparticle extravasation differed between joints and pleura with and without tumor infiltration.

MATERIALS AND METHODS

We retrospectively identified 15 pediatric and young adult patients (mean age: 16±4 years) with bone sarcomas who underwent 18 MRI scans at 1 h (n=7) or 24 h (n=11) after intravenous ferumoxytol infusion. Twelve patients also received a gadolinium-enhanced MRI. We determined tumor invasion into the joint or pleural space based on histology (n=11) and imaging findings (n=4). We compared the signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) of the joint or pleural fluid for tumors with and without invasion using a Mann-Whitney U test.

RESULTS

MRI scans 24 h after intravenous ferumoxytol infusion demonstrated a positive T1 enhancement of the effusion in all joints and pleural spaces with tumor infiltration and no joint or pleural space without infiltration. Corresponding SNR (P=0.004) and CNR (P=0.004) values were significantly higher for joints and pleural spaces with tumor infiltration than without. By contrast, unenhanced MRI, gadolinium-enhanced MRI and 1-h post-contrast ferumoxytol MRI did not show any enhancement of the joint or pleural effusion, with or without tumor infiltration.

CONCLUSION

This pilot study suggests that 24-h post-contrast ferumoxytol MRI scans can noninvasively differentiate between joints with and without tumor infiltration.

Sarcomas: New Biomarkers and Therapeutic Strategies

Bone and soft tissue sarcoma (STS) are heterogeneous diseases comprised of various molecular and histologic subtypes [...].

A novel tool for predicting the survival of endoprosthesis used for reconstruction of the knee following tumor resection: a retrospective cohort study

Background

Prosthesis-related complications, after knee reconstruction with endoprosthesis during operation for tumors around the knee, remain an unresolved problem which necessitate a revision or even an amputational surgery. The purpose of the current study was to identify significant risk factors associated with implant failure, and establish a novel model to predict survival of the prosthesis in patients operated with endoprostheses for tumor around knee.

Methods

We retrospectively reviewed the clinical database of our institution for patients who underwent knee reconstruction due to tumors. A total of 203 patients were included, including 123 males (60.6%) and 80 (39.4%) females, ranging in age from 14 to 77 years (mean: 34.3 ± 17.3 years). The cohort was randomly divided into training (n = 156) and validation (n = 47) samples. Univariable COX analysis was used for initially identifying potential independent predictors of prosthesis survival with the training group (p < 0.150). Multivariate COX proportional hazard model was selected to identify final significant prognostic factors. Using these significant predictors, a graphic nomogram, and an online dynamic nomogram were generated for predicting the prosthetic survival. C-index and calibration curve were used for evaluate the discrimination ability and accuracy of the novel model, both in the training and validation groups.

Results

The 1-, 5-, and 10-year prosthetic survival rates were 94.0, 90.8, and 83.0% in training sample, and 96.7, 85.8, and 76.9% in validation sample, respectively. Anatomic sites, length of resection and length of prosthetic stem were independently associated with the prosthetic failure according to multivariate COX regression model (p<0.05). Using these three significant predictors, a graphical nomogram and an online dynamic nomogram model were generated. The C-indexes in training and validation groups were 0.717 and 0.726 respectively, demonstrating favourable discrimination ability of the novel model. And the calibration curve at each time point showed favorable consistency between the predicted and actual survival rates in training and validation samples.

Conclusions

The length of resection, anatomical location of tumor, and length of prosthetic stem were significantly associated with prosthetic survival in patients operated for tumor around knee. A user-friendly novel online model model, with favorable discrimination ability and accuracy, was generated to help surgeons predict the survival of the prosthesis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08710-x.

Are Cemented Endoprosthetic Reconstructions Superior to Uncemented Endoprostheses in Terms of Postoperative Outcomes and Complications in Patients with Extremity-Located Bone Metastasis Scheduled for Adjuvant Radiotherapy?

BACKGROUND

Adjuvant radiotherapy frequently is used for prevention of recurrence following resection and endoprosthetic reconstruction of bone metastases. Besides this positive effect, radiotherapy can negatively affect both cemented and uncemented endoprostheses.

METHODS

We retrospectively analyzed 130 extremities of 115 patients who underwent resection and cemented or uncemented endoprosthetic reconstruction for bone metastasis, followed by postoperative radiation therapy. The functional improvement was assessed by Karnofsky Performance Scale and Musculoskeletal Tumor Society (MSTS) scoring. The radiological evaluation mainly included analysis of "loosening areas" which were defined as the regions of osteolysis between the stem of the endoprostheses and the cement or cortex. The complications resulting in reconstruction failure and patient survival were recorded.

RESULTS

A survival analysis revealed that 21 (18.3%) patients were alive with disease and 94 (81.7%) died of disease at the time of study. The mean last follow-up Karnofsky Performance Scale and MSTS scores of the whole study cohort were 78.69 ± 8.66 and 82.15 ± 9.06, respectively. There were 8 (6.15%) complications resulting in reconstruction failure, including aseptic loosening (2), femoral stem breakage (2), periprosthetic fracture (2), and infection (2). The number and time of complications did not show a significant difference between the cemented and uncemented groups (P > .05).

CONCLUSION

This study demonstrated that there was no significant difference in complication rates of cemented or uncemented endoprosthetic reconstructions in patients with extremity-located bone metastases scheduled for adjuvant radiotherapy. The only result in favor of cemented prostheses was significantly higher MSTS functional scores at last follow-up.

Comparison of all-polyethylene and metal-backed modular tibial components in endoprosthetic reconstruction of the distal femur

INTRODUCTION

All-polyethylene (AP) tibial components have demonstrated equivalent or improved long-term survivorship and reduced cost compared with metal-backed (MB) components in primary total knee arthroplasty; however, there is a lack of data comparing these outcomes in the setting of an oncologic endoprosthetic reconstruction.

METHODS

A total of 115 (88 AP:27 MB) patients undergoing cemented distal femur endoprosthetic reconstruction following oncologic resection were reviewed. Mean age was 40 years and 51% were females. Cumulative incidences of all-cause revision, tibial component revision, reoperation, and infection were calculated utilizing a competing risk analysis with death as the competitor. Mean follow-up was 14 years.

RESULTS

The 10-year cumulative incidence of all-cause revision was 19.9% in the AP group and 16.3% in the MB group (hazard ratio [HR] = 0.93, p = 0.88). The cumulative incidence of tibial component revision was significantly lower in AP compared with MB at 10 years (1.1% vs. 12.5%, HR = 0.18, p = 0.03). There was no difference in infection-free survival when comparing the two groups (p = 0.72).

CONCLUSIONS

Reconstruction utilizing an MB or AP tibia component resulted in equivalent overall outcome; however, the tibial component in the AP group was less likely to be revised. AP tibial component should be considered for all primary oncologic reconstructions in the distal femur. LEVEL OF EVIDENCE: Level III Therapeutic.

Establishing musculoskeletal oncology service in resource constrained country: challenges and solutions

The burden of orthopedic tumor surgery in Pakistan is not known. Similarly the number of procedures being performed for bone and soft tissue surgery are not known. This is even becoming more challenging where the existence of rules and regulations in health care are next to minimal. Furthermore data recording in our country and case registries hardly exist. Despite the lack of information and resources, with high disease burden on community, various providers provide surgical interventions every day in our settings. A lot of tumor surgery is still being done by general surgeons and general orthopedic surgeons who have little knowledge and update about musculoskeletal oncology principles. Lack of subspecialized centers and the high cost of such centers force the patients to visit these surgeons for a highly sophisticated problem like a bone tumor which is the disease of young bones. In this article we will emphasize on the difficulty in establishing an orthopedic tumor service in our part of the world and the consequences including delay in diagnosis, faulty course of management and later decline in functionality, disease progression and increased mortality. We will highlight the principles and stepwise approach of orthopedic tumor surgery and explain the difficulty encountered if these principles are not followed.

Periprosthetic Fractures in Megaprostheses: Algorithmic Approach to Treatment

With increases in both life expectancy and the number of patients with endoprosthetic replacements, more periprosthetic fractures are expected to occur. Periprosthetic fractures related to megaprostheses present a treatment challenge, with a high incidence (one-third of affected patients) of secondary revision as a result of prosthetic loosening, infection, nonunion, refracture, or even amputation. Efforts to improve endoprosthetic reconstruction should focus on preventing postoperative complications. Understanding the causes of complications and strategies to avoid them could lead to significant improvements in implant survival, limb function, and patient outcomes. This article presents a concise review of the current literature and an algorithmic approach to reconstruction of these complex injuries. [Orthopedics. 2017; 40(3):e387-e394.].

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.

The longitudinal split technique for narrow canal tibia in a case of distal femur replacement for osteosarcoma

•

There are currently no available prostheses that can be used for extremely small femurs or tibias of adult patients.

•

Our novel technique can be used with conventional prostheses.

•

Our novel technique is simple and easy solution in skeletally immature adult patients requiring the resection of distal femur malignant tumors.

Introduction

There are currently no available prostheses that can be used for extremely small femurs or tibias of adult patients in countries where allograft is unavailable.

Case report

We report the case of a 17-year-old girl requiring special limb salvage technique for distal femur reconstruction following resection of malignant tumor. This technique was needed because of a very narrow canal of the tibia. We split bilateral tibial cortices longitudinally with osteotomies to enlarge tibial canal enough to insert conventional endoprosthesis. After insertion of the implant, split tibia reduced with titanium cables and bands, and the split clefts were filled with cancellous bone. Fifteen months after the operation, proper fixation was achieved with bony fusion of bilateral split clefts and ambulation without assistance was achieved.

Discussion

Any proper surgical procedure for our patient were reported previously. We developed a conventional non-expandable endoprosthesis for distal femur replacement using the double longitudinal split technique as a solution to this difficult problem.

Conclusion

Our longitudinal split technique should be applicable to adult patients with skeletal immaturity requiring resection of juxta-articular malignant tumors and in other situations complicated by the presence of a narrow canal.

Management of sarcomas possibly involving the knee joint when to perform extra-articular resection of the knee joint and is it safe?

We reviewed the oncological and functional outcomes of patients treated for a primary sarcoma possibly involving the knee joint and present an algorithm to guide treatment. The records of 76 patients who had a primary bone or soft tissue sarcoma possibly invading the knee between 1996 and 2012 were identified. Mean age and follow-up was 32 years (9-74) and 64 months (12-195), respectively. Patients were grouped according to the resection (Intra-articular [IAR] vs. Extra-articular [EAR] vs. Amputation/rotationplasty) for survival and functional outcomes. Overall 5 and 10 year survival was 61% and 53%, respectively. No differences in survival were found between the 3 groups (p = 0.55). Sixteen patients developed local recurrence with no difference between the groups. Mean MSTS score was 24.5 (12-30). Mean flexion at final follow-up was 106° (70-130°). We conclude that EAR of the knee allows for good oncologic and functional outcomes but with an increased risk of complications compared to IAR. Intra-operative assessment of joint involvement can be done in patients where joint infiltration by the tumour is not clear to avoid an unnecessary EAR. For chondrosarcoma patients with joint involvement, an EAR should be carefully considered because they present a significantly higher local recurrence risk.

Long term outcomes of cemented endoprosthetic reconstruction for periarticular tumors of the distal femur

BACKGROUND

In order to achieve an oncological margin during limb salvage surgery for tumors of the distal femur, part or the entire knee joint is frequently sacrificed. Endoprosthetics make limb salvage possible through restoration of a functional extremity. Currently there remains a paucity of data concerning their long-term outcomes and associated risk factors for failure.

METHODS

We identified 152 patients who underwent an endoprosthetic reconstruction for an oncological process of the distal femur between 1972 and 2013. The mean follow-up was 10years. Mean age and body mass index (BMI) were 39years and 25.8 respectively. The most common pathology was osteosarcoma (n=78, 48%). Outcomes were compared to a control group of 20,643 patients undergoing total knee arthroplasty (TKA) for degenerative joint disease (DJD) during the same time period.

RESULTS

The mean five-, 10-, 15-, 20-, and 25-year revision-free survival for an endoprosthesis was 76%, 63%, 51%, 36%, and 28%. Compared to the five-, 10-, 15-, 20-, and 25-year survival of 95%, 90%, 82%, 74%, and 67% for control TKAs (p<0.0001 at all-time points). Overall limb survival was 93%, with 11 patients undergoing amputation. There was no difference in implant survival comparing modular and custom endoprostheses.

CONCLUSION

The results of this study show that given the complexity of these operations, the rate of revision surgery following endoprosthetic replacement is high. Nevertheless, the use of these modular reconstructions leads to a high rate of limb salvage (93%) over a 25-year period at our institution.

LEVEL OF EVIDENCE

Level III.

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.

Retrospective evaluation of the incidence of early periprosthetic infection with silver-treated endoprostheses in high-risk patients: case-control study

We conducted a case-control study to examine the merit of silver-coated tumour prostheses. We reviewed 85 patients with Agluna-treated (silver-coated) tumour implants treated between 2006 and 2011 and matched them with 85 control patients treated between 2001 and 2011 with identical, but uncoated, tumour prostheses. In all, 106 men and 64 women with a mean age of 42.2 years (18.4 to 90.4) were included in the study. There were 50 primary reconstructions (29.4%); 79 one-stage revisions (46.5%) and 41 two-stage revisions for infection (24.1%). The overall post-operative infection rate of the silver-coated group was 11.8% compared with 22.4% for the control group (p = 0.033, chi-square test). A total of seven of the ten infected prostheses in the silver-coated group were treated successfully with debridement, antibiotics, and implant retention compared with only six of the 19 patients (31.6%) in the control group (p = 0.048, chi-square test). Three patients in the silver-coated group (3.5%) and 13 controls (15.3%) had chronic periprosthetic infection (p = 0.009, chi-square test). The overall success rates in controlling infection by two-stage revision in the silver-coated group was 85% (17/20) compared with 57.1% (12/21) in the control group (p = 0.05, chi-square test). The Agluna-treated endoprostheses were associated with a lower rate of early periprosthetic infection. These silver-treated implants were particularly useful in two-stage revisions for infection and in those patients with incidental positive cultures at the time of implantation of the prosthesis. Debridement with antibiotic treatment and retention of the implant appeared to be more successful with silver-coated implants.

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.

Outcome of expandable prostheses in children

BACKGROUND

Expandable prostheses offer the advantages of limb-salvage and limb-length equality at skeletal maturity. However, what is the cost for achieving that goal, and in how many children this is achieved?

MATERIALS AND METHODS

We present 32 children (16 boys and 16 girls; mean age, 9 y) with bone sarcomas of the femur treated with limb salvage using expandable prostheses. The Kotz Growing prosthesis and the noninvasive Repiphysis and Stanmore expandable prostheses were used. The mean follow-up was 49 months. Survival analysis of the children and primary implants and functional evaluation were performed.

RESULTS

Survival of the children was 94% and 84% at 48 and 72 months. Survival of the primary prostheses was 78% and 66% at 48 and 72 months; survival was significantly higher only for the Kotz when compared with the Repiphysis prostheses (P=0.026). The rate of implant-related complications was 51.3%; 9 prostheses (23%) were revised because of aseptic loosening, infection, and breakage. A mean total lengthening of 28 mm (4 to 165 mm) was achieved by 84 procedures (2.6 procedures/patient). Three of the 9 children who reached skeletal maturity had limb-length equality and 6 discrepancy of 15 to 30 mm. The mean Musculoskeletal Tumor Society score was excellent (79%) without a significant difference between the type of prostheses (P=0.934).

CONCLUSIONS

The Kotz Growing prosthesis, although it requires an open lengthening procedure, has shown higher survival when compared with the noninvasive Repiphysis prosthesis. However, the total lengthening remains small, and the complications rates are high even with the noninvasive prostheses.

Long-term survival of cemented distal femoral endoprostheses with a hydroxyapatite-coated collar: a histological study and a radiographic follow-up

BACKGROUND

The objective of this study was to examine the degree of osteointegration into a hydroxyapatite-coated collar and relate this finding to aseptic loosening in patients with a distal femoral replacement used to treat primary bone cancer. Our hypothesis was that the implant collar would increase osteointegration and reduce the rate of aseptic implant loosening.

METHODS

Sixty-one patients treated with a primary cemented distal femoral prosthesis between 1992 and 2001 were included in this study. The mean duration of follow-up was 8.5 years (range, two to eighteen years). Extracortical bone growth into the grooved hydroxyapatite-coated collar was quantified radiographically. Histological sections through four hydroxyapatite-coated collars and four implants with no collar, retrieved following amputation due to local recurrence or at autopsy at a mean of 3.5 years (range, 1.4 to 6.1 years) after implantation, were evaluated as well.

RESULTS

Five (8%) of the implants were revised because of aseptic loosening, 3% of the implants fractured, and 3% were revised because of infection. Six limbs (10%) required amputation because of local tumor recurrence. On radiographs, osteointegration into the collar was seen to have occurred in 70% of the patients and did not correlate with sex, age, diagnosis, or length of time postoperatively. Histological analysis showed mature lamellar bone within the grooves of the hydroxyapatite-coated collar, and bone was observed in direct contact with the hydroxyapatite coating. Extracortical bone failed to make direct contact with the surface of the implants manufactured without a collar.

CONCLUSIONS

The use of cemented distal femoral massive bone tumor prostheses with a hydroxyapatite-coated collar located at the shoulder of the implant was followed by a low (8%) rate of revision due to aseptic loosening. The use of hydroxyapatite grooved collars may lead to osteointegration of the implant shoulder (collar) and may reduce the rate of aseptic loosening.

High infection rate outcomes in long-bone tumor surgery with endoprosthetic reconstruction in adults: a systematic review

BACKGROUND

Limb salvage surgery (LSS) with endoprosthetic replacement is the most common method of reconstruction following bone tumor resection in the adult population. The risk of a postoperative infection developing is high when compared with conventional arthroplasty and there are no appropriate guidelines for antibiotic prophylaxis.

QUESTIONS/PURPOSES

We sought to answer the following questions: (1) What is the overall risk of deep infection and the causative organism in lower-extremity long-bone tumor surgery with endoprosthetic reconstruction? (2) What antibiotic regimens are used with endoprosthetic reconstruction? (3) Is there a correlation between infection and either duration of postoperative antibiotics or sample size?

METHODS

We conducted a systematic review of the literature for clinical studies that reported infection rates in adults with primary bony malignancies of the lower extremity treated with surgery and endoprosthetic reconstruction. The search included articles published in English between 1980 and July 2011.

RESULTS

The systematic literature review yielded 48 studies reporting on a total of 4838 patients. The overall pooled weighted infection rate for lower-extremity LSS with endoprosthetic reconstruction was approximately 10% (95% CI, 8%-11%), with the most common causative organism reported to be Gram-positive bacteria in the majority of cases. The pooled weighted infection rate was 13% after short-term postoperative antibiotics and 8% after long-term postoperative antibiotics. There was no correlation between sample size and infection rate.

CONCLUSIONS

Infection rates of 10% are high when compared with rates for conventional arthroplasty. Our results suggest that long-term antibiotic prophylaxis decreases the risk of deep infection. However, the data should be interpreted with caution owing to the retrospective nature of the studies.

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.

Total condylar unipolar expandable prosthesis for proximal tibia malignant bone tumors in early childhood

Wide resection and reconstruction of tumors of the proximal tibia in the pediatric population are challenging procedures. The use of hinged, expandable prostheses may cause early closure of the distal femoral growth plate, which may increase the risk of limb discrepancy already present in this population. Between 1991 and 2001, 2 girls and 1 boy, aged 6, 6, and 4 years, respectively, were diagnosed with osteosarcoma of the proximal tibia and treated with wide resection and reconstruction with a condylar unipolar expandable tibial prosthesis. A press-fitted technique was used for component insertion. All patients received neoadjuvant and adjuvant chemotherapy. Radiographic and functional follow-up took place at least once a year for a minimum of 4 years. Adequate pain control, limb-length equality, and acceptable function were obtained in all patients. One patient presented with significant range of motion reduction (0°- 30°) in the affected knee. Limb lengthening was performed as needed to maintain balanced limb length. All patients had a good Musculoskeletal Tumor Society category score. No complications occurred in terms of component loosening or infection. One patient died shortly after 4-year follow-up because of doxorubicin-induced leukemia. Currently used hinged, expandable prostheses can jeopardize the unaffected distal femoral growth plate. This article describes a technique of reconstruction that spares the distal femoral growth plate. Adequate limb length can be expected with acceptable functional outcome. However, it is imperative to keep in perspective the expectations of the physician, the physician's team, the patient, and the patient's family.

Revision of tumor prosthesis of the knee joint

Background

Among 40 patients with primary malignant tumors of the knee joint who underwent reconstruction of the affected limb with tumor prosthesis, revision was required in 7 due to stem breakage or loosening.

Subjects and methods

In the 7 cases undergoing revision, conditions and background factors at the time of breakage, the breakage site, time of revision, models of previous and new prostheses, stem diameters before and after revision, details of the revision (blood loss, operative time), and the presence or absence of adjuvant therapy were determined.

Results

The replacement site was the distal femur in 5 and proximal tibia in 2. Revision was performed 6 years and 2 months after the previous prosthesis placement on average. The broken prosthesis model was KMFTR in 4 and HMRS and the physio-hinge type in one each. Revision due to loosening was performed in a case requiring replacement with Growing Kotz prosthesis. The model was switched to HMRS in 3, and the stem diameter was changed to 12 mm in 3 KMFTR breakage cases. The mean stem diameters were 11.2 and 10.2 mm in the non-revision and revision groups. The respective resection rates were 36 and 45%. The mean functional evaluation was 70.1% before and 76.2% after revision.

Conclusion

To reduce the risk of tumor prosthesis breakage, the amount of bone resection should be limited to 30% or less in the affected bone, the stem diameter should be at least 12 mm, and the stem shape should be fitted to the anatomical shape of the femur.

Proximal and total humerus reconstruction with the use of an aortograft mesh

BACKGROUND

The shoulder is commonly affected by primary and metastatic tumors. Current surgical techniques for complex shoulder reconstruction frequently result in functional deficits and instability. A synthetic mesh used in vascular surgery has the biological properties to provide mechanical constraint and improve stability after tumor related shoulder reconstruction.

QUESTIONS/PURPOSES

We describe (1) surgical technique using a synthetic mesh during humerus reconstructions; (2) functional level defined as shoulder ROM of patients undergoing the procedure; (3) incidence of postoperative dislocation and shoulder instability; and (4) complications associated with the use of the device.

METHODS

We retrospectively reviewed 16 patients with proximal humerus replacements reconstructed with a synthetic mesh from February 2006 to July 2008. Patients were followed clinically and radiographically for a minimum of 13 months (mean, 26 months; range, 13-43 months).

RESULTS

There were no shoulder dislocations at the latest followup. The mean shoulder flexion was 43° (range, 15°-170°) and mean shoulder abduction of 38 (range, 15°-110°). The mean operative time was 121 minutes (range, 80-170 minutes) and the mean blood loss was 220 mL (range, 50-750 mL). One patient had a superficial wound infection and none a deep infection requiring removal of the graft or prosthesis.

CONCLUSIONS

The data suggest the use of a synthetic vascular mesh for proximal humerus reconstruction may reduce dislocations and facilitate soft tissue attachment and reconstruction after tumor resection.

Late complications and survival of endoprosthetic reconstruction after resection of bone tumors

BACKGROUND

While complications following massive endoprosthetic reconstruction have been previously described, the incidence and effects of these complications over extended periods of time have not been well characterized in large series.

QUESTIONS/PURPOSES

We therefore determined: (1) incidence and types of complications; (2) relative risk of complications; (3) likelihood of secondary complications; (4) whether modularity altered such complications; (5) implant failure and limb salvage rates and (6) implant survival over extended followup.

METHODS

We retrospectively reviewed 232 patients (241 implants: 50 custom,191 modular) who underwent endoprosthetic reconstruction for malignant and aggressive bone tumors between 1980 and 2002. Complications were classified as infection, mechanical, superficial soft tissue, deep soft tissue, or dislocation. Survival was determined by Kaplan-Meier analysis. Minimum followup was 5 years (mean: 10 years; range: 5-27 years).

RESULTS

One hundred thirty-seven of 232 patients (59%) underwent a single reconstruction. Ninety-five patients had 242 additional procedures. Forty-four revised patients retained their original prosthesis. Limb salvage rate was 90%; implant failure (removal of the cemented part) was seen in 29% (70/241) with a median survival of 190 months. Twenty-five of 50 custom implants failed (8 then failed again) while 30/180 modular implants failed (7 then failed again). Of 70 instances of implant failure, 38/70 were mechanical, 27/70 infectious. Risk of infection increased 30% after a second procedure; 16 of 24 amputations were performed because of infection.

CONCLUSIONS

Mechanical complications were the most common cause of implant failure. Infection was the leading cause of both complication and amputation; risk of infection increased substantially with revision surgery. Modular implants had fewer mechanical complications, thus leading to fewer revisions and subsequent infections.

Reduction of periprosthetic infection with silver-coated megaprostheses in patients with bone sarcoma

BACKGROUND AND OBJECTIVES

The placement of megaprostheses in patients with bone sarcoma is associated with high rates of infection, despite prophylactic antibiotic administration. In individual cases, secondary amputation is unavoidable in the effort to cure infection.

METHODS

The infection rate in 51 patients with sarcoma (proximal femur, n = 22; proximal tibia, n = 29) who underwent placement of a silver-coated megaprosthesis was assessed prospectively over a 5-year period, along with the treatment administered for infection. The infection rate was compared with the data for 74 patients in whom an uncoated titanium megaprosthesis (proximal femur, n = 33; proximal tibia, n = 41) was implanted.

RESULTS

The infection rate was substantially reduced from 17.6% in the titanium to 5.9% in the silver group. Whereas 38.5% of patients in the titanium group ultimately had to undergo amputation when periprosthetic infection developed, these mutilating surgical procedures were not necessary in the study group.

CONCLUSIONS

The use of silver-coated prostheses reduced the infection rate in the medium term. In addition, less aggressive treatment of infection was possible in the group with silver-coated prostheses. Further studies with longer term follow-up periods and larger numbers of patients are warranted in order to confirm these encouraging results.

Cancer, chitosan nanoparticles and catalytic nucleic acids

Objectives

The aim of this review was to examine gene therapy involving DNAzyme and siRNA encapsulation into chitosan nanoparticles, discussing the current and future status of this drug delivery system in enhancing drug delivery and cancer therapy.

Key findings

Cancer is a disease state in which the cells in our body undergo mutations at the genetic level and are transformed, acquiring the ability to replicate limitlessly. Conventional cancer treatment involves the use of surgery and cytotoxic chemotherapy and/or radiotherapy, which have the potential of harming normal, otherwise healthy, non-neoplastic cells. Newer forms of therapy such as immunotherapy and gene therapy have shown initial promise, but still require better ways to limit exposure to cancerous lesions in the body. As a result drug delivery systems have been developed in attempts to deliver therapeutics specifically to the target lesion site. One recent drug delivery system has revolved around the use of chitosan nanoparticle technology, where therapeutics are encapsulated into nanoparticles and targeted to tumours.

Summary

Though few, attempts at encapsulating therapeutics such as deoxyribozymes and small or short interfering RNA have been optimistic and encouraging.

The long-term risks of infection and amputation with limb salvage surgery using endoprostheses

Endoprostheses are now an established technique to reconstruct defects following bone tumour resection. The long-term durability of the reconstruction is excellent, with limb salvage being maintained in the long-term in 91% of patients at 20 years from surgery. The main reasons for secondary amputation were locally recurrent disease and deep periprosthetic infection. Infection remains one of the biggest threats to early failure of reconstructions with endoprostheses. Most series of reconstructions show a periprosthetic infection rate of approximately 10%. Infection most frequently occurs within 12 months from the last surgical procedure; however, the risk of infection is life-long. The commonest pathogenic organism is coagulase-negative Staphylococcus. The most effective treatment for deep infection is two-stage revision, with local treatments having little chance of curing deep infection. Research is on-going into surface treatments with silver and other materials to help to reduce the infection rates.