Limb function and quality of life after various reconstruction methods according to tumor location following resection of osteosarcoma in distal femur

Limb salvage surgery reconstructive techniques following long-bone lower limb oncological resection: a systematic review and meta-analysis

BACKGROUND

Limb salvage surgery (LSS) is now considered the gold standard surgical treatment for lower limb bone sarcomas. However, there is a paucity of literature comparing the various LSS reconstructive options. The aim of this systematic review and meta-analysis was to compare functional outcomes and complications of LSS reconstructive techniques.

METHODS

The primary aim of the meta-analysis was to determine functional outcomes from the pooled data utilizing the Musculoskeletal Tumour Society score (MSTS). Comparisons could then made for this outcome between biological and prosthetic, vascularised and non-vascularised, and prosthetic and composite reconstructions. The secondary aim was to compare complication outcomes of each reconstruction. Standardized mean difference (Cohen's d) and odds ratios were estimated using a random effects model.

RESULTS

Fourteen studies with a total of 785 patients were included. We found structural failure was 75% less likely to occur in prosthetic reconstruction compared to biological (OR = 0.24; 95% CI: 0.07-0.79; P = 0.02). We did not find any evidence of difference in function (MSTS score) between vascularised verses non-vascularised reconstructions (Cohen's d = -1.14; 95% CI = -3.06 to 0.78; I2  = 87%). Other analyses comparing complications found no difference between the reconstructive groups.

CONCLUSION

The study found no correlation between functional outcomes and the type of LSS reconstruction. Structural failure was more likely to occur in biological when compared with prosthetic reconstruction. There was no correlation between the incidence of other complications and the type of LSS technique. This suggests a role for improved approaches to reconstruction methods including bioprinting and bioresorbable devices.

Limb salvage surgery for calcaneal chondrosarcoma: A case report

BACKGROUND

Limb salvage surgery for calcaneal sarcomas remains challenging due to its poor compartmentalization. While below-knee amputation is still the standard choice of operative treatment, total calcanectomy with or without reconstruction was advocated. This report aims to analyze the clinical outcome of calcaneal reconstruction with cement and replantation in situ after the inactivation of tumor.

METHODS

We describe a 73-year-old male patient who suffered chronic pain and increasingly larger neoplasm in the left foot for about 3 years. Based on the results of percutaneous biopsy, a diagnosis of chondrosarcoma was made.

RESULTS

The patient underwent total calcanectomy, inactivation of calcaneus tumor, and reconstruction with cement. The Achilles tendon was detached through a Cincinnati incision. No adverse events occurred both during and after the surgery. At the last follow-up of 29 months, the patient claimed no pain, no evident limp, or any limitation of daily activities. Image examination, weight-bearing test, and MSTS score revealed a satisfactory result.

CONCLUSION

Calcaneal reconstruction with bone cement after total calcanectomy, inactivation of calcaneus tumor, and replantation in situ is likely to provide a feasible surgical choice and a satisfactory clinical outcome.

Predictors of Functional Recovery among Musculoskeletal Oncology Patients Undergoing Lower Extremity Endoprosthetic Reconstruction

BACKGROUND AND OBJECTIVES

Functional outcomes are important for oncology patients undergoing lower extremity reconstruction. The objective of the current study was to describe patient reported function after surgery and identify predictors of postoperative function in musculoskeletal oncology patients undergoing lower extremity endoprosthetic reconstruction.

METHODS

We performed a cohort study with functional outcome data from the recently completed Prophylactic Antibiotic Regimens in Tumor Surgery (PARITY) trial. We utilized the 100-point Toronto Extremity Salvage Score (TESS), which was administered pre-operatively and at 3, 6 and 12 months post-operatively. Higher scores indicate better physical functioning, and the minimally important difference is 11 points. We calculated mean functional scores at each timepoint after surgery and developed a logistic regression model to explore predictors of failure to achieve excellent post-operative function (TESS ≥ 80) at 1 year after surgery.

RESULTS

The 555 patients included in our cohort showed important functional improvement from pre-surgery to 1 year post-surgery (mean difference 14.9 points, 95%CI 12.2 to 17.6; p < 0.001) and 64% achieved excellent post-operative function. Our adjusted regression model found that poor (TESS 0-39) pre-operative function (odds ratio [OR] 3.3, 95%CI 1.6 to 6.6); absolute risk [AR] 24%, 95%CI 8% to 41.2%), older age (OR per 10-year increase from age 12, 1.32, 95%CI 1.17, 1.49; AR 4.5%, 95%CI 2.4% to 6.6%), and patients undergoing reconstruction for soft-tissue sarcomas (OR 2.3, 95%CI 1.03 to 5.01; AR 15.3%, 95%CI 0.4% to 34.4%), were associated with higher odds of failing to achieve an excellent functional outcome at 1-year follow-up. Patients undergoing reconstruction for giant cell tumors were more likely to achieve an excellent functional outcome post-operatively (OR 0.40, 95%CI 0.17 to 0.95; AR -9.9%, 95%CI -14.4% to -0.7%).

CONCLUSIONS

The majority of patients with tumors of the lower extremity undergoing endoprosthetic reconstruction achieved excellent function at 1 year after surgery. Older age, poor pre-operative function, and endoprosthetic reconstruction for soft tissue sarcomas were associated with worse outcomes; reconstruction for giant cell tumors was associated with better post-operative function.

LEVEL OF EVIDENCE

Therapeutic Level IV.

Bevacizumab Combined with Intensity-Modulated Radiation Therapy on Cognitive and Coagulation Function in Postoperative Glioma Patients

To examine the influences of bevacizumab combined with intensity-modulated radiation therapy (IMRT) on postoperative brain glioma, particularly its impact on coagulation function and cognitive function, the complete clinical data of 156 patients undergoing glioma surgery in the neurosurgery department of our hospital between March 2015 and October 2018 were retrospectively analyzed. All patients underwent glioma surgery and were then assigned to the observation group (Obs group, n = 79, received bevacizumab combined with IMRT) or the control group (Con group, n = 77, received IMRT without bevacizumab) for analysis during postoperative treatment. The patients' short-term efficacy was evaluated, and their serum markers and coagulation function were compared, as well as the cognitive function, the occurrence of adverse reactions during treatment, the Karnofsky performance status (KPS) score, and quality of life after treatment. Patients' survival was followed up within 2 years after surgery. The Obs group showed a notably higher clinical remission rate and clinical control rate (DCR) than the Con group after treatment. The Obs group showed notably lower levels of interleukin-2 (IL-2), vascular endothelial growth factor (VEGF), IL-6, and epidermal growth factor (EGF), experienced notably shorter prothrombin time (PT) and activated partial thromboplastin time (APTT), and showed higher fibrinogen (FIB) and D-dimer (D-D) levels than Con group. The Obs group showed notably better cognitive function, KPS score, and quality of life than the Con group, but no notable difference was observed between them in the incidence of adverse reactions (P > 0.0500). The survival rates in the Obs group were higher than in the Con group. For patients with glioma, postoperative bevacizumab combined with IMRT delivers substantially higher clinical efficacy by lowering serum marker levels and improving cognitive function without significantly affecting coagulation function.

Amputation Predisposes to Higher Cancer-Specific Mortality Than Limb Salvage Surgery in Pediatric Patients With Osteosarcoma of the Limbs: A Propensity Matching Analysis

Objective

With the development of osteosarcoma treatment, limb salvage surgery is gradually replacing amputation as the primary surgical option. Most pediatric osteosarcomas of the limbs undergo limb-salvage surgery. We aimed to use propensity score matching (PSM) analysis test the difference in cancer-specific mortality (CSM) between amputation and limb-salvage surgery in pediatric patients with Osteosarcoma of the limbs. PSM is a statistical method used to deal with data from an Observational Study. The PSM method is designed to reduce the influence of biases and confounding variables to make a more reasonable comparison between experimental and control groups.

Methods

Patient information was downloaded from the SEER (surveillance, epidemiology, and End Results) database from 2004 to 2018. We included all primary pediatric osteosarcoma patients who underwent limb salvage or amputation. Multivariate logistic regression models were used to explore the factors influencing patient choice of amputation. Differences in CSM and other causes of mortality (OSM) between limb salvage and amputation were analyzed using cumulative incidence plots and competitive risk regression tests after 1:1 proportional propensity score matching.

Results

A total of 1,058 pediatric patients with limbs Osteosarcoma were included. Patients who underwent amputations were more likely to be male (OR 1.4, P = 0.024) and more likely to have distant metastasis (OR 2.1, P &lt; 0.001). Before propensity matching, CSM was 1.4 times higher in patients undergoing amputation than in patients undergoing limb salvage (P = 0.017) and 3.4 times higher in OSM (P = 0.007). After adjustment for propensity matching, CSM was 1.5 times higher in patients undergoing amputation than in patients undergoing limb salvage (P = 0.028), but there was no significant difference in OSM (HR 3.2, P = 0.078).

Conclusions

Our results suggested that amputation is associated with a 1.5-fold increase in CSM in pediatric patients with limbs Osteosarcoma. Therefore, in the surgical selection of pediatric patients with Osteosarcoma, limb salvage surgery should be the first choice in the absence of other contraindications.

Comparative efficacy of intraoperative extracorporeal irradiated and alcohol-inactivated autograft reimplantation for the management of osteosarcomas-a multicentre retrospective study

BACKGROUND

Biologic bone reconstruction in limb salvage surgery for the treatment of malignant bone tumours has always been controversial. The various inactivation methods, their convenience and stability, the curative effects elicited and associated costs all need to be considered. This study aimed to compare the clinical efficacy of intraoperative extracorporeal irradiated reimplantation with alcohol-inactivated autograft reimplantation for limb salvage surgery in patients with osteosarcoma.

METHODS

We retrospectively analysed 28 patients with osteosarcoma, 14 patients treated with intraoperative cobalt 60 irradiation and reimplantation (group A), and 14 patients treated by alcohol-inactivated autograft reimplantation (group B). The postoperative complications and clinical efficacy of each treatment method were compared by statistical analysis.

RESULTS

The local recurrence rate was 14.3% in each group. Complete bony union was achieved in 64.3% of patients in group A and 71.4% of patients in group B. The overall 5-year survival rate was 71.4% in group A and 78.6% in group B. The mean Musculoskeletal Tumor Society (MSTS) score was 25.33 ± 4.72 (range 15-30) in group A and 24.00 ± 5.85 (range 15-30) in group B, and the mean International Society of Limb Salvage (ISOLS) score was 25.79 ± 5.13 (range 20-36) in group A and 26.14 ± 5.33 (range 20-30) in group B. P < 0.05 was considered to indicate a significant difference. The results showed that the long-term clinical efficacy did not differ significantly between the two methods.

CONCLUSIONS

In limb salvage surgery for osteosarcoma, intraoperative extracorporeal irradiation and alcohol-inactivated autograft reimplantation yielded equivalent outcomes. The alcohol-inactivated method may be a much more convenient and inexpensive way to reconstruct bone defects. Additional studies as well as more case studies are needed to fully evaluate the clinical efficacy and safety of this treatment method.

The therapeutic effects of X-ray devitalization and replantation and alcoholic devitalization and replantation in adolescent patients with lower limb osteosarcoma

OBJECTIVE

To compare and analyze the therapeutic effects of X-ray devitalization and replantation and alcoholic devitalization and replantation in adolescent patients with lower limb osteosarcoma.

METHODS

We collected clinical data for 43 osteosarcoma patients with limb salvage treatment treated in our hospital from February 2014 to February 2018. The patients were divided into x-ray devitalization and replantation group (n=23) and alcoholic devitalization and replantation group (n=20) based on the treatment methods. The two groups were compared in operation duration, intraoperative blood loss, postoperative fracture healing time, length of tumor bones, MSTS score and ISOLS score, postoperative complications, postoperative follow-ups and postoperative recurrence and metastases.

RESULTS

Operation duration and intraoperative blood loss of the alcoholic group were less than that of the X-ray group, while postoperative fracture healing time of the alcoholic group was longer than that of the X-ray group (P<0.05). For the X-ray group, MSTS score and ISOLO score of the final follow-up were 26.13±2.65 and 32.53±3.73 respectively. For the alcoholic group, MSTS score and ISOLO score of the final follow-up were 23.69±3.27 and 30.98±3.56 respectively. MSTS score of the X-ray group was higher than that of the alcoholic group (P<0.05). There were 2 cases of internal fixation failure and 2 cases of adhesive knee joints stiffness in the X-ray group. As for the alcoholic group, there were 2 cases of internal fixation failure and 2 cases of incision soft tissue infection. There were no statistically significant differences in postoperative complications, recurrence, and metastases between the two groups (P>0.05).

CONCLUSION

Both methods are convenient, inexpensive, and effective for adolescent patients with lower limb osteosarcoma. Alcoholic devitalization and replantation results in shorter operation duration and less intraoperative blood loss, while X-ray devitalization and replantation results in better postoperative limb function restoration.

Predictors and Survival of Patients with Osteosarcoma After Limb Salvage versus Amputation: A Population-Based Analysis with Propensity Score Matching

BACKGROUND

Conflicting findings have been reported concerning the survival of patients treated with limb salvage and amputation for osteosarcoma. This study aimed to identify predictors associated with surgery types and survival difference.

METHODS

Patients with osteosarcoma were selected from the Surveillance Epidemiology and End Results database (1975-2016). Multivariable logistic regression analysis was conducted, and a nomogram was further established. Propensity score matching (PSM)-adjusted Kaplan-Meier curves, log-rank tests, Cox proportional hazards regression analysis were performed to compare overall survival (OS) and cancer-specific survival (CSS).

RESULTS

Among 3363 patients with osteosarcoma, 2447 and 916 underwent limb salvage and amputation. Predictors associated with amputation in the nomogram included age, gender, primary tumor site, tumor grade, tumor stage, tumor size and radiotherapy. Totally 900 pairs of patients treated with limb salvage and amputation were matched after PSM. Limb salvage was significantly associated with improved OS (HR, 0.773; 95% CI, 0.670-0.892; p < 0.001) and CSS (HR, 0.795; 95% CI, 0.681-0.927; p = 0.003) in PSM-adjusted cohort after adjusting for related variables. The significant treatment effect of limb salvage was consistent within most subgroups. Among patients treated with surgery for osteosarcoma, age between 41 and 60, age ≥ 61, pelvis as the primary site, high tumor grade (III/IV), regional and distant tumor stage, tumor size ≥ 92 mm and radiotherapy were independent prognostic factors in PSM cohort.

CONCLUSIONS

Limb salvage exhibits significant benefit on OS and CSS compared with amputation for osteosarcoma. Predicators and survival differences should be given full consideration for the treatment of osteosarcoma.

Outcome of segmental prosthesis reconstruction for diaphyseal bone tumors: a multi-center retrospective study

Background

The optimal reconstructive method after diaphyseal malignant bone tumor resection remains controversial. This multicenter clinical study was designed to investigate the clinical value and complications of segmental prosthesis in the repair of diaphyseal defects.

Methods

We present 49 patients from three clinical centers treated with wide resection for primary or metastatic bone tumors involving the diaphysis of the femur, tibia, humerus, or ulna, followed by reconstruction using a modular intramedullary segmental prosthesis.

Results

Enrolled patients included 23 men and 26 women with a mean age of 63.3 years. Of these, seven patients had primary bone tumors and 42 patients had metastatic lesions. At the mean follow-up of 13.7 months, 17 patients were alive, 31 patients were deceased due to tumor progression, and one patient was dead of another reason. There were eight nononcologic complications (two with radial nerve injury, three with delayed incision healing, two with aseptic loosening in the proximal humerus prosthetic stem and one with structural failure) and three oncologic complications (three with primary tumor recurrence) among all patients. The incidence of complications in primary tumor patients (4/7, 57.1%) was higher than that in patients with metastatic tumors (7/42, 16.7%) (p = 0.036). Aseptic loosening and mechanical complications were not common for patients with primary tumors, although the reconstruction length difference was statistically significant (p = 0.023). No statistically significant differences were observed in limb function, while the mean musculoskeletal tumor society score was 21.2 in femora, 19.6 in humeri, and 17.8 in tibiae (p = 0.134).

Conclusions

Segmental prostheses represent an optional method for the reconstruction of diaphyseal defects in patients with limited life expectancy. Segmental prostheses in the humerus experienced more complications than those used to treat lesions in the femur.

Fitness, Function, and Exercise Training Responses after Limb Salvage With a Lower Limb Megaprosthesis: A Systematic Review

OBJECTIVE

To describe the fitness, function, and exercise training responses of patients following reconstruction of the lower limb with a total femoral (TF), proximal femoral (PF), distal femoral (DF), or proximal tibial (PT) megaprosthesis. TYPE: Systematic review.

LITERATURE SURVEY

Five research databases were searched systematically for original studies published in English from 2006 to 2017 that reported fitness, functioning, or exercise training responses for one or more of the four types of lower limb megaprosthesis listed above.

METHODOLOGY

Methodologic quality was assessed using a 22-item modified STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) checklist.

SYNTHESIS

Of the 5342 articles retrieved, 28 met the inclusion criteria. Thirteen studies reported fitness outcomes, primarily in PT, with none in TF. Impaired knee extensor strength of the affected limb was reported following limb salvage with PF, DF, and PT megaprosthetics. Impaired flexibility was reported following limb salvage with DF and PT megaprosthetics. Functional outcomes were described in all studies and were most commonly reported using the Musculoskeletal Tumor Society (MSTS) system score. Results indicated no clear difference in functional outcomes between megaprosthesis locations. No studies evaluated exercise training responses.

CONCLUSIONS

This review identified impairments of lower limb strength and flexibility following limb salvage with a lower limb megaprosthesis. Similarity in functional outcomes for all four reported megaprosthetic locations may indicate a lack of sensitivity in outcome measures, including the absence of items assessing higher-level functioning. Exercise interventions that aim to improve fitness and function in this population have not been evaluated but are required given increasing 5-year survival rates.

LEVEL OF EVIDENCE

I.

Screw migration and oesophageal perforation after surgery for osteosarcoma of the cervical spine

Background

Even though internal fixation has expanded the indications for cervical spine surgery, it carries the risks of fracture or migration, with associated potential life threatening complications. Removal of metal work from the cervical spine is required in case of failure of internal fixation, but it can become challenging, especially when a great amount of scar tissue is present because of previous surgery and radiotherapy.

Case presentation

We report a 16 year old competitive basketball athlete who underwent a combined anterior and posterior approach for resection of an osteosarcoma of the sixth cervical vertebra. Fourteen years after the index procedure, the patient eliminated spontaneously one screw through the intestinal tract via an oesophageal perforation and developed a severe dysphagia. Three revision surgeries were performed to remove the anterior plate because of the great amount of post-surgery and post-irradiation fibrosis.

Conclusions

Screw migration and oesophageal perforation after cervical spine surgery are uncommon potentially life-threatening occurrences. Revision surgery may be challenging and it requires special skills.

Alcohol Devitalization and Replantation for Primary Malignant Bone Tumors of the Knee Joint

BACKGROUND

This paper is aimed at studying the therapeutic effects of in situ replantation of alcohol-devitalized bone segments to treat malignant bone tumors of the knee joint.

METHODS

We retrospectively analyzed clinical data for 45 patients from January 2013 to January 2016 who underwent replantation following alcohol-devitalization of bone segments and 40 who underwent prosthesis implantation. The two groups were comparable in basal clinical biometric data, including gender, age, tumor type and location, Enneking staging, and maximum tumor diameter. Radical tumor resection was combined with neoadjuvant chemotherapy following the two-implantation procedures.

RESULTS

The median follow-up time was 25 months, and the outcomes were compared. We found no differences in the length of bone lesions, surgery time, intraoperative blood loss, amount of postoperative drainage, and perioperative complications, which were just three for each method. We also found no significant differences in limb function scores, internal fixation imaging scores, tumor-free survival rate, and overall survival rate between the two groups. Replantation following alcohol-devitalization of tumor-bearing bone segment demonstrated similar clinical outcomes compared with prosthesis implantation in the treatment of primary malignant bone tumors of the knee joint.

CONCLUSION

Both therapies enjoy good application safety and effectiveness. Because alcohol devitalization is inexpensive and easy to apply in the clinic, it should be considered a preferred method in the treatment of bone tumors.

The application of 3D printed surgical guides in resection and reconstruction of malignant bone tumor

The clinical value of 3D printed surgical guides in resection and reconstruction of malignant bone tumor around the knee joint were studied. For this purpose, a sample of 66 patients from October 2013 to October 2015 were randomly selected and further divided into control group and observation group, each group consisted of 33 cases. The control group was treated by conventional tumor resection whereas, in the observation group, the tumor was resected with 3D printed surgical guide. However, reconstruction of tumor-type hinge prosthesis was performed in both groups and then the clinical effect was compared. Results show that there was no significant difference in the operation time between the two groups (p>0.05). However, the blood loss, resection length and complication rate were found significantly lower in the observation group than in the control group (p<0.05). The rate of negative margin and the recurrence rate in the 12-month follow-up (p>0.05) between two groups were statistically the same (p>0.05), whereas the Musculoskeletal Tumor Society (MSTS) score of the knee joint in the observation group was significantly better than that of the control group (p<0.05) after 1, 3, 6 and 12 months of the operation. Consequently, the 3D printed surgical guides can significantly improve the postoperative joint function after resection and reconstruction of malignant bone tumor around the knee joint and can reduce the incidence of complications.

Can a Bayesian Belief Network Be Used to Estimate 1-year Survival in Patients With Bone Sarcomas?

BACKGROUND

Extremity sarcoma has a preponderance to present late with advanced stage at diagnosis. It is important to know why these patients die early from sarcoma and to predict those at high risk. Currently we have mid- to long-term outcome data on which to counsel patients and support treatment decisions, but in contrast to other cancer groups, very little on short-term mortality. Bayesian belief network modeling has been used to develop decision-support tools in various oncologic diagnoses, but to our knowledge, this approach has not been applied to patients with extremity sarcoma.

QUESTIONS/PURPOSES

We sought to (1) determine whether a Bayesian belief network could be used to estimate the likelihood of 1-year mortality using receiver operator characteristic analysis; (2) describe the hierarchal relationships between prognostic and outcome variables; and (3) determine whether the model was suitable for clinical use using decision curve analysis.

METHODS

We considered all patients treated for primary bone sarcoma between 1970 and 2012, and excluded secondary metastasis, presentation with local recurrence, and benign tumors. The institution's database yielded 3499 patients, of which six (0.2%) were excluded. Data extracted for analysis focused on patient demographics (age, sex), tumor characteristics at diagnosis (size, metastasis, pathologic fracture), survival, and cause of death. A Bayesian belief network generated conditional probabilities of variables and survival outcome at 1 year. A lift analysis determined the hierarchal relationship of variables. Internal validation of 699 test patients (20% dataset) determined model accuracy. Decision curve analysis was performed comparing net benefit (capped at 85.5%) for all threshold probabilities (survival output from model).

RESULTS

We successfully generated a Bayesian belief network with five first-degree associates and describe their conditional relationship with survival after the diagnosis of primary bone sarcoma. On internal validation, the resultant model showed good predictive accuracy (area under the curve [AUC] = 0.767; 95% CI, 0.72-0.83). The factors that predict the outcome of interest, 1-year mortality, in order of relative importance are synchronous metastasis (6.4), patient's age (3), tumor size (2.1), histologic grade (1.8), and presentation with a pathologic fracture (1). Patient's sex, tumor location, and inadvertent excision were second-degree associates and not directly related to the outcome of interest. Decision curve analysis shows that clinicians can accurately base treatment decisions on the 1-year model rather than assuming all patients, or no patients, will survive greater than 1 year. For threshold probabilities less than approximately 0.5, the model is no better or no worse than assuming all patients will survive.

CONCLUSIONS

We showed that a Bayesian belief network can be used to predict 1-year mortality in patients presenting with a primary malignancy of bone and quantified the primary factors responsible for an increased risk of death. Synchronous metastasis, patient's age, and the size of the tumor had the largest prognostic effect. We believe models such as these can be useful as clinical decision-support tools and, when properly externally validated, provide clinicians and patients with information germane to the treatment of bone sarcomas.

CLINICAL RELEVANCE

Bone sarcomas are difficult to treat requiring multidisciplinary input to strategize management. An evidence-based survival prediction can be a powerful adjunctive to clinicians in this scenario. We believe the short-term predictions can be used to evaluate services, with 1-year mortality already being a quality indicator. Mortality predictors also can be incorporated in clinical trials, for example, to identify patients who are least likely to experience the side effects of experimental toxic chemotherapeutic agents.

All-polyethylene tibial components in distal femur limb-salvage surgery: a finite element analysis based on promising clinical outcomes

Background

Whether all-polyethylene tibial (APT) components are beneficial to patients who received distal femur limb-salvage surgery lacks high-quality clinical follow-up and mechanical evidence. This study aimed to investigate the biomechanics of the distal femur reconstructed with APT tumor knee prostheses using finite element (FE) analysis based on our previous, promising clinical outcome.

Methods

Three-dimensional FE models that use APT and metal-backed tibial (MBT) prostheses to reconstruct distal femoral bone defects were developed and input into the Abaqus FEA software version 6.10.1. Mesh refinement tests and gait simulation with a single foot both in the upright and 15°-flexion positions with mechanical loading were conducted. Stress distribution analysis was compared between APT and MBT at the two static positions.

Results

For both prosthesis types, the stress was concentrated on the junction of the stem and shaft, and the maximum stress in the femoral axis base was more than 100 Mpa. The stress on the tibial surface was relatively distributed, which was 1–19 MPa. The stress on the tibial bone-cement layer of the APT prosthesis was approximately 20 times higher than that on the MBT prosthesis in the same region. The stress on the proximal tibial cancellous bone and cortical bone of the APT prosthesis was 3–5 times greater than that of the MBT prosthesis, and it was more distributed.

Conclusions

Although the stress of bone-cement around the APT component is relatively high, the stress was better distributed at the polyethylene-cement-bone interface in APT than in MBT prosthesis, which effectively protects the proximal tibia in distal femur tumor knee prosthesis replacement. These results should be considered when selecting the appropriate tibial component for a patient, especially under the foreseeable conditions of osteoporosis.

Impacts of Tumor Location, Nature and Bone Destruction of Extremity Osteosarcoma on Selection of Limb Salvage Operative Procedure

OBJECTIVE

To study the impacts of tumor location, nature and extent of bone destruction on selection of operative protocol for extremity osteosarcoma (OS).

METHODS

The medical records of 201 patients with extremity OS treated in our institute from December 1999 to June 2014 were retrospectively reviewed. Ninety eligible patients (56 males and 34 females) of average age 20 ± 11 years (range, 4-40 years) were enrolled. Tumor locations were categorized as diaphyseal (4; diaphysis group) or juxta-articular (86); the latter being subclassified as with (51, type III, epiphysis group) or without invasion beyond the epiphyseal line or plate (35, type I and II, metaphysis group) according to MRI images. Tumor nature (osteogenic, 51; osteolytic, 39) was determined radiologically. Extent of bone destruction was quantitated according to Mirel's scoring system to obtain an "invasion score". Regular postoperative follow-up included physical examination and imaging evaluation.

RESULTS

Fifty-four patients underwent biological reconstruction and 36 mechanical reconstruction. The mean follow-up duration was 51 months (range, 6-176 months, including four deaths within 12 months). Biological reconstruction was performed more frequently in the diaphysis and metaphysis groups (31/39, 79.5%) than mechanical reconstruction (8/39, 20.5%, P < 0.05). Biological reconstruction and articular preservation were associated with more satisfactory limb function (MSTS scores: 25.0 ± 3.3 and 25.1 ± 3.6) than mechanical reconstruction and articular resection (MSTS scores: 23.4 ± 3.7 and 23.1 ± 3.4, P < 0.05). Reconstruction methods and articular preservation had no relationship with overall or tumor-free survival (P > 0.05). Osteolytic lesions were associated with more extensive bone destruction than osteogenic lesions according to invasion scores (P < 0.05). Following biological reconstruction, high invasion scores (>8) had a 13.5-fold risk of fracture compared with low scores (≤8) (P < 0.05). Twenty-one subjects had recurrences, 30 metastases and 26 died. Postoperative complications included infection (6), fracture (10), and prosthesis loosening (4). Kaplan-Meier analysis indicated 5- and 10-year survival rates of 68.9% and 62.8%, respectively, and 5- and 10-year tumor-free survival rates of 66.7% and 57.8%, respectively.

CONCLUSION

Selection of limb salvage operative protocol for extremity OS should rely on tumor location, nature and extent of bone destruction. Regardless of tumor site, mechanical reconstruction is indicated for tumors with high invasion scores (>8), whereas biological reconstruction is preferred for those with low invasion scores (≤8). Tumors sparing the epiphyseal line or plate are ideal candidates for articular preservation.

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.