Incidence and management of secondary deformities after megaendoprosthetic proximal femur replacement in skeletally immature bone sarcoma patients.

INTRODUCTION: Megaendoprosthetic reconstruction of bone defects in skeletally immature patients has led to the development of unique complications and secondary deformities not observed in adult patient cohorts. With an increasing number of megaendoprosthetic replacements performed, orthopedic oncologists still gain experience in the incidence and type of secondary deformities caused. In this study, we report the incidence, probable cause and management outcome of two secondary deformities after megaendoprosthetic reconstruction of the proximal femur: hip dysplasia and genu valgum. MATERIALS AND METHODS: Retrospective analysis of 14 patients who underwent primary and/or repeat reconstruction/surgery with a megaendoprosthetic proximal femur replacement between 2018 and 2022. RESULTS: Mean patient age was 9.1 years (range 4-17 years). Stress shielding was observed in 71.4%. Hip dislocation was the most frequent complication (50%). While four dislocations occurred without an underlying deformity, secondary hip dysplasia was identified in 58.3% (n = 7/12) of intraarticular resections and reconstructions, leading to dislocation in 71.4% (n = 5/7). A genu valgum deformity was observed in 41.6% (n = 5/12). The incidence of secondary hip dysplasia and concomitant genu valgum was 42.9% (n = 3/7). Triple pelvic osteotomy led to rebound hip dysplasia in two cases (patients aged < 10 years), whereas acetabular socket replacement led to stable hip joints over the course of follow-up. Temporary hemiepiphyseodesis was applied to address secondary genu valgum. CONCLUSIONS: Patients aged < 10 years were prone to develop secondary hip dysplasia and genu valgum following proximal femur replacement in this study. Management of secondary deformities should depend on remaining skeletal growth. Stress shielding was observed in almost all skeletally immature patients.

Reconstruction survival of segmental megaendoprostheses: a retrospective analysis of 28 patients treated for intercalary bone defects after musculoskeletal tumor resections.

INTRODUCTION: Intercalary endoprosthetic reconstructions have been reserved for patients with a limited life expectancy due to reports of high rates of early mechanical and reconstruction failure. MATERIALS AND METHODS: In this study, we retrospectively analyzed 28 patients who underwent intercalary endoprosthetic reconstruction of the femur (n = 17) or tibia (n = 11) regarding reconstruction survival and causes of complications and reconstruction failure. RESULTS: A total of 56 stems were implanted in this collective, 67.9% of which were implanted using cementation. Eight different stem designs were implanted. The mean patient age at the time of operation was 42.3 years. The mean bone defect needing reconstruction measured 18.5 cm. Resection margins were clear in 96.4% of patients. Of twenty-six complications, five were not implant-associated. We observed infection in 10.7% (n = 3) and traumatic periprosthetic fracture in 3.6% (n = 1) of cases. The most frequent complication was aseptic stem loosening (ASL) (53.8%; n = 14) occurring in eight patients (28.6%). The metaphyseal and meta-diaphyseal regions of femur and tibia were most susceptible to ASL with a rate of 39.1% and 31.3% respectively. No ASLs occurred in epiphyseal or diaphyseal location. Overall reconstruction survival was 43.9% and 64.3% including patients who died of disease with their implant intact. Overall limb survival was 72.7%. CONCLUSIONS: Proper planning of segmental reconstructions including stem design with regard to unique anatomical and biomechanical properties is mandatory to address the high rates of ASL in metaphyseal and metadiaphyseal stem sites. With continued efforts of improving stem design in these implantation sites and decreasing rates of mechanical failure, indications for segmental megaendoprostheses may also extend to younger patients with the localized disease for their advantages of early weight bearing and a lack of donor-site morbidity.

[Strategic approach to pathological fractures]. / Strategisches Vorgehen bei pathologischen Frakturen.

Pathological tumor-associated fractures are overall rare. They can occur in every age group and every bone. Although tumor-related fractures only form a small proportion of bone fractures, the early recognition of the cause of the fracture and treatment according to oncological guidelines are of enormous importance for affected patients. False treatment is frequently associated with far-reaching negative consequences with respect to the course of the disease. The great challenge is not the expeditious surgical treatment but much more the adequate diagnostics and the incorporation of local fracture treatment into an interdisciplinary overall oncological concept.

Megaprosthetic replacement of the distal humerus: still a challenge in limb salvage.

BACKGROUND: The distal humerus is a rare location of bone tumors. Because of the complexity of the elbow joint, poor soft-tissue coverage, and proximity of nerves and vessels, resection and endoprosthetic reconstruction are demanding. METHODS: This retrospective study evaluated the clinical results after distal humeral resection and megaprosthetic reconstruction in 12 patients with an average age of 46 years. All patient files were reviewed for clinical information, and postoperative function and patients' contentment were assessed using the Musculoskeletal Tumor Society score. RESULTS: The predominant diagnoses were bone and soft-tissue sarcoma (n = 6), giant cell tumor (n = 2), and renal cell carcinoma metastasis (n = 2). Local recurrence was the reason for secondary amputation in all cases (n = 3). The prosthetic survival rate after surgery was 82% at 2 years and 64% at 5 years. Reconstruction failure was mainly caused by aseptic loosening of the humeral stem, occurring in 27% (n = 3), followed by aseptic loosening of the ulnar stem in 9% (n = 1) and periprosthetic infection in 9% (n = 1). The mean Musculoskeletal Tumor Society score was 24 points (range, 20-30 points). An extension lag of more than 10° was noted in 6 patients (55%). CONCLUSION: Our results suggest that limb salvage with a distal humeral replacement can achieve good functional results in most patients, although the complication rate with special emphasis on the loosening rate of the humeral stem is high. However, limb salvage was not achieved in 27% of patients because of local recurrence.

Silver-coated megaprostheses in the proximal femur in patients with sarcoma.

BACKGROUND: Proximal femur replacements in patients with sarcoma are associated with high rates of infection. This study is the largest one comparing infection rates with titanium versus silver-coated megaprostheses in sarcoma patients. METHODS: Infection rates were assessed in 99 patients with proximal femur sarcoma who underwent placement of a titanium (n = 35) or silver-coated (n = 64) megaprosthesis. Treatments administered for infection were also analyzed. RESULTS: Infections occurred in 14.3% of patients in the titanium group, in comparison with 9.4% of those in the silver group, when the development of infection was the primary end point. The 5- and 10-year event-free survival rates for the prosthesis relative to the parameter of infection were 90% in the silver group and 83% in the titanium group. The overall infection rates were 10.9% in the silver group and 20% in the titanium group. Two patients each in the silver and titanium groups ultimately had to undergo amputation. The need for two-stage prosthesis exchanges (57.1% in the titanium group) declined to 14.3% in the silver group. CONCLUSION: Using a silver-coated proximal femoral replacement nearly halved the overall infection rate. When infections occurred, it was usually possible to avoid two-stage prosthesis exchanges in the silver group.

Tumour endoprosthesis replacement in the proximal tibia after intra-articular knee resection in patients with sarcoma and recurrent giant cell tumour.

PURPOSE: Proximal tibia replacements are commonly associated with post-operative complications and poor functional results due to an insufficiency of the extensor mechanism. METHODS: This study evaluated the clinical results with a special emphasis of the extensor mechanism reconstruction with a reattachment tube and complications after intra-articular resection of the proximal tibia and reconstruction with a tumour endoprosthesis (MUTARS®) in 98 patients (median age 18 years) with malignant bone tumours or giant cell tumours. RESULTS: Kaplan-Meier analysis showed that the limb survival rates were 94.9, 90.5 and 74.5% at one, two and ten years, respectively. Periprosthetic infection was the most common reason for secondary amputation (eight patients). The cumulative incidence rates of prosthetic failure (Henderson II-IV) were 18% at two years and 29% at five years post-operatively. An active extension deficit of more than 10° was noted in six patients only. CONCLUSIONS: These results suggest that limb salvage with tumour prostheses after intra-articular resection can achieve good functional results with an active extension of the knee in the majority of patients. While mechanical complications can be treated successfully with revision surgery, periprosthetic infection continues to be the main reason for secondary amputation.

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.

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.

Forequarter amputation: a safe rescue procedure in a curative and palliative setting in high-grade malignoma of the shoulder girdle.

BACKGROUND: Forequarter amputation (FQA) is a surgical treatment of tumors in the upper extremity and shoulder girdle that infiltrate the neurovascular bundles. In both curative and palliative settings, FQA can serve as an effective oncological treatment. METHODS: This study presents the FQA-related data of 30 patients (mean age 50 years) treated between 2000 and 2012. Their medical condition was high-grade bone or soft tissue sarcoma in 26 and high-grade carcinoma in four cases. RESULTS: Mean operation time was 119 min. One major and five minor complications occurred in the postoperative period. Resection margins were wide in 91 % of patients. Local recurrence was observed in four patients after 19 months on average. Patients treated with curative intention had a 5-year survival chance of 39 %. Average survival after palliative amputation was 11 months. CONCLUSIONS: FQA provides an opportunity for adequate oncological margins in large tumors, while offering relief from tumor-induced distress in palliative situations.

Analysis of surgical and oncological outcome in internal and external hemipelvectomy in 34 patients above the age of 65 years at a mean follow-up of 56 months.

BACKGROUND: With an increasing life expectancy and improved treatment regimens for primary or secondary malignant diseases of soft tissue or bone, hemipelvectomy will have to be considered more often in elderly patients in the future. Scientific reviews concerned with the surgical and oncological outcome of elderly patients undergoing hemipelvectomy are scarce. Therefore, it is the purpose of this study to review the outcome of patients treated with that procedure at our hospital and investigate the feasibility of such extensive procedures at an increased age. METHODS: A retrospective analysis of thirty-four patients who underwent hemipelvectomy at an age of 65 years or older was performed to determine their surgical and oncological outcome. The Kaplan-Meier method was used to calculate the cumulative probability of survival using the day of tumor resection as a starting point. Univariate analysis was carried out to investigate the influence of a particular single parameter. RESULTS: The mean age at operation was 70.2 years. Thirty patients were treated for intermediate- to high-grade sarcoma and 81.8% of tumors were larger than or equal to 10 cm in the longest diameter. Thirteen patients underwent internal hemipelvectomy and nine patients external hemipelvectomy as a primary procedure. Twelve patients were treated with external hemipelvectomy after failed local tumor control at primary operation. Wound infection occurred in 61.7% of cases. Three patients underwent amputation for non-manageable infection after internal hemipelvectomy. Hospital mortality was 8.8%. Clear resection margins were obtained in 88% of patients; in another 6% of patients planned intralesional resections were performed. Local recurrence occurred in 8.8% of patients at a mean time of 26 months after operation. Eleven patients are alive with no evidence of disease and 23 patients died of disease or other causes. Patients with pulmonary metastases had a mean survival period after operation to DOD of 22 months compared to 37 months in the curative group. CONCLUSION: Despite an elevated rate in hospital mortality and wound infection, this study suggests that hemipelvectomy is feasible in elderly patients, although requiring long hospitalization periods and causing a limited functional outcome.

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.

Improvement of the shoulder function after large segment resection of the proximal humerus with the use of an inverse tumour prosthesis.

PURPOSE: Active shoulder function after segmental tumour resection of the proximal humerus and endoprosthetic reconstruction is regularly compromised, while the overall arm function allows a satisfying use in daily activities. The main functional problem remains the loss of huge parts of the shoulder girdle musculature and its bony attachment. In revision arthroplasty inverse shoulder implants can improve the active range of motion significantly in comparison to anatomical shaped prostheses. The aim of this study was to investigate if these promising experiences are transferable to reconstructions after tumour resection of the proximal humerus by using a modular inverse tumour prosthesis. METHODS: In this study we observed the functional and oncological results of 18 inverse proximal humerus endoprosthetic replacements (IPHP) with the MUTARS system (Implantcast®) after resection of benign (1x giant cell) and malignant (11x primary bone sarcoma, 5x bone metastasis of carcinoma) bone tumours. Mean age at operation was 42 years. The mean postoperative follow-up was 33 months (range ten to 120). RESULTS: Resection margins were wide in 13 and marginal in five patients. Mean reconstruction length was 15.1 cm (range 6-25 cm). Mean operation time was 191 minutes. The axillary nerve was mostly preserved in 78 % (n = 14). At latest follow-up the patients presented a medium MSTS-score of 24.6/30. The mean active arm abduction in the shoulder joint was 78° and 88° active arm elevation for patients with intact axillary nerve function, but significantly reduced for the four patients with compromised deltoid function. One patient needed a surgical revision due to a deep implant infection. CONCLUSIONS: The IPHP offers a significant improvement of active shoulder function in patients in whom the axillary nerve can be preserved in comparison to anatomically-shaped implants. However, for patients without any deltoid function there is no benefit regarding an improved active range of motion using an IPHP.

Modular tumor endoprostheses in surgical palliation of long-bone metastases: a reduction in tumor burden and a durable reconstruction.

BACKGROUND: Surgical treatment of bone metastases has become increasingly important as patients live longer with metastatic cancer and one of the main aims is a long-lasting reconstruction which survives the patient. Conventional osteosynthesis may not be able to achieve this objective in the context of modern day cancer care. METHODS: This study evaluates the oncological outcomes, treatment-related complications, and function after resection of metastases and reconstruction with modular tumor endoprostheses in 80 patients. All patients who underwent surgical treatment with modular tumor prostheses for bone metastases from 1993 to 2008 were traced by our tumor database and clinical information was recorded from patient case. RESULTS: Mean age was 63 years. The most common primary tumors were renal cell (47%), breast (21%), and lung (8%). The proximal femur was affected in 45%, proximal humerus in 26%, and the distal femur in 17% of cases. In 22 cases, the tumor prosthesis was implanted during a revision operation. Mean overall survival after surgery was 2.9 years. Overall survival rate was 70% at one year and 20% at five years. Implant survival was 83% after one year and 74% at five years. Overall rate of operative revision was 18%. CONCLUSIONS: Our data collectively suggest that despite higher costs, implantation of modular tumor endoprostheses may be a suitable treatment for bone metastases with a low complication rate and rapid improvement in function in appropriately selected patients.

Slipped capital femoral epiphysis after tumor prosthesis implantation in a patient receiving chemotherapy.

While the usual etiology of slipped capital femoral epiphysis (SCFE) is idiopathic, there are many other factors that increase the predisposition to slippage. Chemotherapy can be one of them. In this article, we report a rare case of acute SCFE after tumor prosthesis implantation in a patient who received chemotherapy. A 10-year-old girl with osteosarcoma of the right distal femur underwent (neo-) adjuvant chemotherapy, wide tumor resection, and reconstruction using a growing tumor prosthesis and a short non-cemented femoral stem. Half a year after implantation, she developed aseptic loosening. Revision surgery was performed using a hydroxyapatite (HA)-coated cementless femoral stem. Postoperative plain radiographs revealed SCFE that was treated by closed reduction and screw fixation. The patient recovered without complications, and unaffected hip showed no radiographic signs of slippage on follow-up. The forces of implanting a tumor prosthesis, particularly with a non-cemented stem, can increase the risk of an acute SCFE. The controversy over prophylactic pinning of the uninvolved hip in chemotherapy-associated SCFE is unresolved. Pinning can be considered only in the presence of abnormal prodromal radiological findings.

Return to Sports and Activity in Tumor Orthopaedics. / Wiederkehr zu körperlicher Aktivität und Sport in der Tumororthopädie.

As survival rates associated with the multimodal treatment of malignant bone cancer (osteosarcoma and Ewing's sarcoma) are satisfactory, health-related quality of life and the return to activity and sports by the affected patients have attracted increasing attention in recent years. Nowadays, limbs can be salvaged for most patients using modular endoprostheses. Such patients are typically adolescents and young adults who have high activity levels and thereby high demands for multimodal cancer treatment. This study aimed to evaluate the activity levels and sporting proficiencies that can be attained after modular endoprosthetic treatment of bone sarcomas as well as the extent to which physiotherapeutic and sports interventions influence functional outcome and activity levels.This non-systematic review of the literature focused on the return to activity and sports after modular endoprosthetic treatment of lower extremities bone sarcomas in adolescents and young adults. The electronic database PubMed was screened for relevant publications on this issue. A treatment algorithm for return to activity and sports in tumor orthopaedics is proposed.The objective activity level (gait cycles per day and gait intensities) in patients treated for bone sarcomas is reduced in short- and long-term follow-ups compared with healthy controls and patients with other cancers (leukaemia). Although a negative impact is observed in terms of motor performance, it shows improvement over time. Functional assessment at 12 postoperative months is sensible as neoadjuvant chemotherapy is completed by then. In long-term follow-up, patients with bone sarcomas can achieve high sports activity levels, i.e., type of sport, frequency/week and UCLA score, after modular endoprosthetic reconstruction. The maximum level is attained at 5 years postoperatively. Nevertheless, there is a shift from high- and intermediate- to low-impact sports. Only 20% of the patients participate in school sports regularly without limitations. The localisation of bone sarcoma, but not the rate of postoperative complications, influences the postoperative activity level. Individualised sports-related interventions during and after multimodal treatment can improve the short-term activity levels; moreover, "serious games" can improve motor performance and postural control. There is no evidence that intense activity levels leads to early loosening of the endoprosthesis. There is insufficient valid data on activity and sports after modular endoprosthetic treatment of bone sarcomas of the upper extremities.High preoperative activity levels of young patients with bone sarcomas must be considered in tumour orthopaedics. Limitations on sports activities have a significant negative impact on the quality of life and mental health of such patients. Therefore, tumour orthopaedic treatment has to focus on preserving an improvement in these factors. The overall existing evidence concerning this issue is weak. Additional studies to evaluate the ability to return to specific sports activities are desirable, as well as prospective interventional studies.

Pathological Fractures in Benign Bone Lesions - Diagnosis and Therapy. / Die pathologische Fraktur bei benignen Knochenläsionen - Diagnostik und Therapie.

INTRODUCTION: Most tumour-related pathological fractures occur in patients with bone metastases. However, in mostly younger patients, a pathological fracture can be due to both a benign or a malignant bone tumour. Making the correct diagnosis from among these two differential diagnoses is enormously important. If the tumour is malignant, treating the fracture inevitably leads to tumour cell contamination and can significantly worsen the oncological situation. The aim of this review article is firstly to provide the reader with diagnostic assistance in the case of suspected pathological fractures, and secondly to focus on the treatment of pathological fractures occurring with benign bone tumours. METHODS: This is a non-systematic review of the diagnosis and treatment of pathological fractures in benign bone tumours or tumour-like lesions, based on an electronic PubMed database search. We also present our own procedures, in particular for ruling out a malignant bone tumour. RESULTS AND DISCUSSION: Whenever a fracture occurs in the absence of sufficient traumatic force, the possibility of a pathological fracture should always be considered. As well as taking a general history for a possible primary tumour, it is particularly important to ask the patient whether they had any pain before the fracture occurred. If the findings from clinical examination or conventional radiological imaging give rise to suspicion of a pathological fracture, an MRI of the affected skeletal section with contrast medium should be carried out before commencing any fracture treatment. A CT scan is also helpful for accurately assessing bone destruction. If a malignant or locally aggressive benign bone tumour such as giant cell tumour (GCT) or aneurysmal bone cyst (ABC) cannot be definitively ruled out through imaging, a biopsy is essential. The bone biopsy must always be carried out on the assumption that the histological work-up will reveal a malignant bone tumour; it must therefore be performed according to strict oncological criteria. If the radiological diagnosis is unambiguous, e. g., a juvenile bone cyst (JBC) or a non-ossifying fibroma (NOF), conservative treatment of the fracture can be considered, depending on the location. In the presence of a locally aggressive benign bone tumour such as a GCT or ABC, curettage of the tumour must be carried out as well as treating the fracture. With GCT in particular, neoadjuvant therapy with denosumab prior to curettage and osteosynthesis or en bloc resection of the tumour should be considered, depending on the extent of the tumour. CONCLUSION: Pathological fractures, especially in younger patients, should not be overlooked. Only after a malignant or benign locally aggressive bone tumour has been definitively ruled out should fracture treatment be performed. In the presence of a locally aggressive bone tumour, as well as treating the fracture, it is usually necessary to perform curettage of the tumour - also en bloc resection, where applicable, in the case of a GCT. Depending on the location, benign, non-aggressive tumours can be treated conservatively if necessary.

Highly Cancellous Titanium Alloy (TiAl6V4) Surfaces on Three-Dimensionally Printed, Custom-Made Intercalary Tibia Prostheses: Promising Short- to Intermediate-Term Results.

Custom-made, three-dimensionally-printed (3D) bone prostheses gain increasing importance in the reconstruction of bone defects after musculoskeletal tumor resections. They may allow preservation of little remaining bone stock and ensure joint or limb salvage. However, we believe that by constructing anatomy-imitating implants with highly cancellous titanium alloy (TiAl6V4) surfaces using 3D printing technology, further benefits such as functional enhancement and reduction of complications may be achieved. We present a case series of four patients reconstructed using custom-made, 3D-printed intercalary monobloc tibia prostheses treated between 2016 and 2020. The mean patient age at operation was 30 years. Tumor resections were performed for Ewing sarcoma (n = 2), high-grade undifferentiated pleomorphic bone sarcoma (n = 1) and adamantinoma (n = 1). Mean resection length was 17.5 cm and mean operation time 147 min. All patients achieved full weight-bearing and limb salvage at a mean follow-up of 21.25 months. One patient developed a non-union at the proximal bone-implant interface. Alteration of implant design prevented non-union in later patients. Mean MSTS and TESS scores were 23.5 and 88. 3D-printed, custom-made intercalary tibia prostheses achieved joint and limb salvage in this case series despite high, published complication rates for biological and endoprosthetic reconstructions of the diaphyseal and distal tibia. Ingrowth of soft tissues into the highly cancellous implant surface structure reduces dead space, enhances function, and appears promising in reducing complication rates.

Acrylic bone cements: influence of time and environment on physical properties.

Acrylic bone cements are in extensive use in joint replacement surgery. They are weight bearing and load transferring in the bone-cement-prosthesis complex and therefore, inter alia, their mechanical properties are deemed to be crucial for the overall outcome. In spite of adequate preclinical test results according to the current specifications (ISO, ASTM), cements with inferior clinical results have appeared on the market. The aim of this study was to investigate whether it is possible to predict the long term clinical performance of acrylic bone cement on the basis of mechanical in vitro testing. We performed in vitro quasistatic testing of cement after aging in different media and at different temperatures for up to 5 years. Dynamic creep testing and testing of retrieved cement were also performed. Testing under dry conditions, as required in current standards, always gave higher values for mechanical properties than did storage and testing under more physiological conditions. We could demonstrate a continuous increase in mechanical properties when testing in air, while testing in water resulted in a slight decrease in mechanical properties after 1 week and then levelled out. Palacos bone cement showed a higher creep than CMW3G and the retrieved Boneloc specimens showed a higher creep than retrieved Palacos. The strength of a bone cement develops more slowly than the apparent high initial setting rate indicates and there are changes in mechanical properties over a period of five years. The effect of water absorption is important for the physical properties but the mechanical changes caused by physical aging are still present after immersion in water. The established standards are in need of more clinically relevant test methods and their associated requirements need better definition. We recommend that testing of bone cements should be performed after extended aging under simulated physiological conditions. Simple quasistatic and dynamic creep tests seem unable to predict clinical performance of acrylic bone cements when the products under test are chemically very similar. However, such testing might be clinically relevant if the cements exhibit substantial differences.

Pelvic Ewing sarcoma: a retrospective outcome analysis of 104 patients who underwent pelvic tumor resection at a single supra-regional center.

BACKGROUND: Local treatment in pelvic Ewing sarcoma (ES) consists of operation, radiation therapy, or a combination of both. Reported outcomes vary depending on the treatment modality performed. It is the objective of this study to analyze surgical outcome and complications as well as oncological outcome and complications of chemo- and radiation therapy in this patient cohort and evaluate prognostic factors. METHODS: Retrospective review of 104 patients who underwent tumor resection for pelvic ES from 1988 to 2014. RESULTS: All patients underwent pelvic resection and radiation therapy was administered in 77.9%. Margins were clear in 94.2%. The response to chemotherapy was good in 78.8%. Local recurrence occurred in 7.7%. The presence of distant metastases at the time of operation was the most important negative predictor for overall survival (p = 0.003). The cumulative 5- and 10-year survival rates were 82.7% and 80.1% for non-metastasized and 61.4% and 41.6% for metastasized pelvic ES at operation. In the presence of a single-distant metastatic site at operation compared to multiple metastatic sites, the cumulative survival rates were 64.3% versus 50% at five and 50.7% versus 16.7% at 10 years. CONCLUSIONS: A combined treatment approach of tumor resection and radiation therapy leads to a local control and overall survival rates comparable with those of extremity locations in this study's patient cohort with localized pelvic ES. Therefore, surgical tumor resection (combined with (neo-)adjuvant radiation therapy) in non-metastatic pelvic ES seems feasible. In metastatic patients, however, the significance of tumor resection as a part of local treatment remains less certain and improved outcomes of combined local treatment approaches need to be weighed against these patients' prognosis and quality of life.

Intra-articular soft-tissue sarcoma of the knee: Is extra-articular resection and tumor endoprosthetic reconstruction the solution? A retrospective report on eight cases.

Intra-articular sarcoma of the knee joint is a very rare condition. Extra-articular resection and reconstruction with a tumor prosthesis is usually performed. This report describes the results with this rare surgical procedure. This retrospective study evaluated the clinical and functional results after extra-articular resection of the knee joint in eight patients with soft-tissue sarcomas of the knee that were reconstructed using a tumor endoprosthesis. Five of the eight patients (62.5%) ultimately had to undergo amputation, mainly due to periprosthetic infection. In addition, two patients experienced periprosthetic fractures. The mean Musculoskeletal Tumor Society score was 18 (range 10-22), as function was impaired due to a weak extensor mechanism. These results suggest that in patients with intraarticular soft-tissue sarcomas, limb salvage procedures with tumor prostheses after extra-articular resection are associated with very high complication rates. In most cases, long-term limb salvage was not possible. When limb salvage is successful, function is also poor due to a weak extensor mechanism in the knee joint. The indication for this procedure should therefore be considered critically.