Pathological Fractures in Benign Bone Lesions - Diagnosis and Therapy

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.

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.

Return to Sports and Activity in Tumor Orthopaedics

INTRODUCTION

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.

METHODS

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.

RESULTS AND DISCUSSION

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.

CONCLUSION

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.

[Strategic approach to pathological fractures]

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.

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.

[Treatment concepts for complications after resection and defect reconstruction of pelvic tumours]

BACKGROUND

Partial pelvic resection, internal hemipelvectomy or sacrectomy as a result of bone sarcoma is still challenging. No matter what kind of reconstruction is used, there is still a much higher rate of complications in pelvic surgery compared to sarcoma surgery of the long bones.

OBJECTIVES

We describe the most common complications in pelvic sarcoma surgery and specific complications related to the reconstruction method. Handling strategies for these complications are specified.

METHODS

We performed a literature search and report our own experiences in the troubleshooting of pelvic surgery-related complications to gain an up-to-date overview of the state-of-the-art in management strategies.

RESULTS

Prospective randomized trials or meta-analyses on this topic are lacking. The literature search depicted that, besides local recurrence, deep infection after reconstruction is the most serious complication. An early revision with radical debridement has to be performed in order to save the reconstruction. In the case of a deep infection, the removal of all implants with a total loss of the reconstruction is often unavoidable. Therefore, an individualized risk-benefit analysis prior to surgery with respect to the type of reconstruction, or no reconstruction at all (hip transposition), together with the patient is advisable.

CONCLUSIONS

Complications-especially infections-after hemipelvectomy or sacrectomy are common. In the case of infection, in some cases, an early revision is the only chance to prevent a reconstruction from explantation.

[Complication management following resection and reconstruction of the upper limbs and shoulder girdle]

BACKGROUND

Sarcomas of the upper limbs commonly affect the proximal humerus or scapula. Complications after tumor resection and reconstruction are rare but cannot be neglected, particularly after tumor endoprosthetic reconstructions.

MATERIALS AND METHODS

The most common complications after resection of sarcomas of the upper limbs and shoulder girdle are described, and current knowledge regarding complication management is presented. Additionally, a selective literature search was performed, incorporating personal experiences.

RESULTS

Wound healing disorders and infections after tumor resection without specific reconstruction (clavicle resection, scapulectomy) usually respond well to conservative or surgical treatment. However, periprosthetic infections after reconstruction using a megaendoprosthesis constitute a severe and frequent complication, with an incidence of 5-10%. Two-stage implant replacement still represents the gold standard, although in selected cases, one-stage revision with retention of the prosthetic stem appears warranted. Secondary amputation as a result of periprosthetic infection is rare compared to the situation with infections of the lower limb. Mechanical complications necessitating surgical revision are mostly limited to joint dislocation after inverse total shoulder replacement (TSR). (Sub)luxation in anatomic TSR can be tolerated provided there is no tendency toward perforation of the skin in a asymptomatic patient. Biological reconstructions are most often indicated for reconstruction of intercalary defects of the humerus, and revision is necessitated most frequently by mechanical complications. Despite multiple surgical revisions, stable reconstructions and limb salvage can usually be achieved in the upper limb.

[Hemipelvectomy for pelvic sarcomas]

BACKGROUND

Hemipelvectomy is an important technique for the treatment of pelvic sarcomas.

OBJECTIVES

Presentation of the technical overview, as well as surgical and oncological outcomes of sarcoma patients treated with pelvic tumor resections and treatment recommendations.

METHODS

Retrospective analysis of 160 patients treated by pelvic tumor resection for chondrosarcoma between 1977 and 2014.

RESULTS

Chondrosarcoma was the most common diagnosis leading to pelvic tumor resection in this collective (38%). The mean patient age at operation was 49 years. 44 patients were treated for G1, 83 patients for G2 and 33 patients for G3 or dedifferentiated chondrosarcoma. The mean tumor diameter was ≥10 cm in 76.1% of cases. Limb salvaging operations were possible in 82.5% of patients. The most common reconstruction technique was hip transposition (38.7%). Clear resection margins were achieved in 86.9% (R0). Local recurrence was observed in 22.5%. Distant pulmonal metastasis was diagnosed in 25% of patients. Grading-specific survival was 81.8% for G1, 59% for G2 and 24.2% for G3 or dedifferentiated chondrosarcoma with a mean survival of 84.4, 89 and 69.4 months respectively.

CONCLUSIONS

Pelvic tumor resection with clear margins is the most important known positive predictive local factor affecting overall outcomes, in addition to uncontrollable factors such as grading and tumor size. Defect reconstruction depends on multiple factors such as patient age and adjuvant therapy. The stage of the disease has the greatest impact on overall survival rates and should be considered when contemplating pelvic tumor resections in sarcoma patients.

[Endoprostheses for stump formation after hip disarticulation]

BACKGROUND

Hip disarticulation is a psychologically and physically demanding procedure. However, it remains a therapeutical option whenever limb salvage proves impossible due to sarcoma, severe implant-associated infections or trauma. The stump lengthening procedure (SLP) is a surgical technique that allows partial salvage of the thigh through endoprosthetic proximal femur replacement after hip disarticulation, depending on the amount of viable soft tissue coverage. This leads to a more appealing visual appearance, facilitates prosthetic fitting and significantly improves limb function.

OBJECTIVES

Description of indications for SLP, surgical technique, presentation of clinical and functional outcomes.

METHODS

Review of applying literature and presentation of outcomes of our own SLP collective.

RESULTS

The risk of local recurrence does not increase after SLP compared to hip disarticulation. While the majority of patients can be fitted with an exoprosthesis, a walking aid is usually necessary for ambulation. Exoprostheses are usually worn throughout the entire day, and patients manage distances of a mean of 2000 metres, even if reconstruction lengths are less than 10 cm. Patients aged 50 years or older tend to wear their exoprosthesis for shorter periods of daywear and achieve significantly poorer functional scores. Postoperative complications are common at a rate of 52%. Periprosthetic infection (21%) and soft tissue perforation of the implant with subsequent implant-associated infection (14%) were the most severe complications observed.

CONCLUSIONS

The stump lengthening procedure poses a feasible alternative to classic hip disarticulation in patients with multiple prior operations and/or advanced stages of disease. It leads to satisfactory cosmetic and functional results without jeopardizing local tumor control. Stump perforation presents as the most common complication. Apart from improving the ability to sit down comfortably, both patients treated with a curative and palliative intent manage to ambulate using exoprostheses. With increasing age at the time of operation, walking aids are necessary for ambulation.

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.

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.

Ultra-short stem anchorage in the proximal tibial epiphysis after intercalary tumor resections: analysis of reconstruction survival in four patients at a mean follow-up of 56 months

INTRODUCTION

Tumors localized in the proximal tibial meta-diaphysis often lead to osteoarticular resections.

MATERIALS AND METHODS

In this study, we retrospectively reviewed four patients who underwent intercalary tumor resection and reconstruction using an ultra-short stem in the proximal tibial epiphysis, a procedure that to our knowledge has not been reported in literature so far.

RESULTS

At the time of operation, the mean patient age was 26.2 years. Three patients were male and one was female. Patients were diagnosed with osteosarcoma in two cases, Ewing's sarcoma and malignant fibrous histiocytoma of bone in one case each. In all cases, wide tumor resections were achieved (osteotomy 3-3.5 cm below the tibia plateau joint surface, mean resection length of tibial bone 18 cm) at a mean time of operation of 198.8 min. Two superficial wound-healing disorders occurred, leading to one surgical revision in each case. One local tumor recurrence occurred 12 months after operation in a patient who discontinued his adjuvant chemotherapy. This patient died of disease, 31 months after operation. Three patients are alive with no evidence of disease at a mean follow-up of 56 months. Walking is not impaired and light sports activities have been reported in all cases. The mean MSTS score is 28/30.

CONCLUSIONS

Therefore, we report this reconstruction technique to be considered for special indications where the functional outcome can be improved by preservation of the knee joint in tumors of the proximal meta-diaphyseal tibial region.

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.

[Benign cartilage tumors. What should I do with incidental findings?]

BACKGROUND

The majority of benign bone tumors are cartilage tumors. Most common are enchondroma and osteochondroma. Often they represent incidental findings in radiological diagnostics. Thus, the incidence of cartilage tumors is unknown, as most of them are never diagnosed due to the absence of any symptoms.

OBJECTIVES

This article describes the diagnostic and therapeutic approach of benign cartilage tumors, focusing on incidental findings.

METHODS

The current knowledge and our own experience in the diagnostics and treatment of benign condroid tumors are presented.

RESULTS

As enchondroma represent most often the classic incidental finding without any symptoms or clinical findings, osteochondroma are often diagnosed in young patients by clinical examination showing a painless swelling that can increase in size according to skeletal growth. Most of these asymptomatic enchondroma and osteochondroma are so called "leave me alone lesions" and do not need any treatment, while other benign tumors (e.g., atypical cartilage tumors, chondroblastoma, chondromyxoidfibroma or osteochondroma with a cartilage cap of over 2 cm) need surgical treatment. These active or local aggressive tumors must be differentiated from the "leave me alone lesions". Additionally, patients with syndromes like Ollier disease (enchondromatosis), Maffucci syndrome or hereditary multiple exostosis must be examined and checked carefully as malignant degradation is possible.

CONCLUSION

As most cartilage tumors are benign and remain benign, inappropriate diagnostics or operative treatment just to provide security is obsolete. Plain X-ray is often enough for follow-up and other modalities only become necessary when symptoms occur.

[Interdisciplinary diagnostic and treatment of bone sarcomas of the extremities and trunk]

Contrary to the relatively common benign bone tumours and tumour-like lesions, bone sarcomas are rare malignancies with an incidence of 0.8 new cases per 100 000 persons per year. The most common primary malignant bone tumour is osteosarcoma, followed by chondrosarcoma and Ewing sarcoma. Osteosarcomas and Ewing sarcomas occur predominantly in children, adolescents and young adults, while chondrosarcomas primarily affect older patients. Most of the tumours are located in the extremities and the pelvis and in about 90% of the cases the surgical treatment can be performed by means of a limb-sparing wide resection. An endoprosthetic or biological reconstruction of the resulting defect, depending on several patient- und tumour-related factors, is usually necessary. Apart from the surgical treatment, patients with osteosarcoma and Ewing sarcoma require a pre- and postoperative chemotherapy, while Ewing sarcoma patients often undergo radiation therapy as well. Regular follow-up examinations are required after the completion of treatment for the early detection and management of local and/or systemic recurrences as well as treatment-related complications. An extensive experience in the clinical and imaging features as well as the interdisciplinary treatment of these tumours is necessary for optimal patient care. Without it mistakes are often made, which can have grave consequences on the patients' prognosis and functional outcome. The centralised treatment of these patients in specialised sarcoma centres is therefore recommended.

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.

[New surgical treatment options for bone tumors]

Primary bone neoplasms can be classified into benign, locally/aggressive and rarely metastasizing and malignant tumors. Patients with benign tumors usually undergo surgical treatment in cases of local symptoms, mainly consisting of pain or functional deficits due to compression of important anatomical structures, such as nerves or blood vessels. Locally/aggressive and rarely metastasizing tumors exhibit an infiltrative growth pattern, so that surgical treatment is necessary to prevent further destruction of bone leading to local instability. Finally, the surgical treatment of malignant tumors is, with few exceptions, considered to be a prerequisite for long-term survival, either alone or in combination with systemic chemotherapy. Whereas the main objective of surgery in the treatment of benign tumors is relief of local symptoms with a minimum amount of damage to healthy tissue and minimizing the risk of local recurrence while ensuring bone stability in locally aggressive and rarely metastasizing tumors, the primary goal in the operative treatment of bone sarcomas is the resection of the tumor with clear surgical margins followed by defect reconstruction and the preservation of function. This review examines the current developments in the surgical treatment of primary bone neoplasms with respect to the management of the tumors and novel reconstructive options.

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.

Insight opinion to surgically treated metastatic bone disease: Scandinavian Sarcoma Group Skeletal Metastasis Registry report of 1195 operated skeletal metastasis

The number of cancer patients living with metastatic disease is growing. The increased survival has led to an increase in the number of cancer-induced complications, such as pathologic fractures due to bone metastases. Surgery is most commonly needed for mechanical complications, such as fractures and intractable pain. We determined survival, disease free interval and complications in surgically treated bone metastasis. Data were collected from the Scandinavian Skeletal Metastasis Registry for patients with extremity skeletal metastases surgically treated at eight major Scandinavian referral centres between 1999 and 2009 covering a total of 1195 skeletal metastases in 1107 patients. Primary breast, prostate, renal, lung, and myeloma tumors make up 78% of the tumors. Number of complications is tolerable and is affected by methods of surgery as well as preoperative radiation therapy. Overall 1-year patient survival was 36%; however, mean survival was influenced by the primary tumor type and the presence of additional visceral metastases. Patients with impending fracture had more systemic complications than those with complete fracture. Although surgery is usually only a palliative treatment, patients can survive for years after surgery. We developed a simple, useful and reliable scoring system to predict survival among these patients. This scoring system gives good aid in predicting the prognosis when selecting the surgical method. While it is important to avoid unnecessary operations, operating when necessary can provide benefit.

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.

Performance of bone cements: are current preclinical specifications adequate?

BACKGROUND

Current specifications (standards) for preclinical testing of bone cements (ISO 5833: 2002, ASTM F451-99a) require simple mechanical testing after ageing for 24 h under dry conditions at 23 degrees C. Some bone cements have fulfilled the requirements in the specifications, and yet had inferior clinical results. Clinically, bone cements are subjected to complex loading patterns in a moist or wet environment at 37 degrees C. Thus, both the validity and the robustness of current standard testing protocols can be questioned.

METHODS

We examined the influence of temperature and storage medium on the properties of bone cement. We also compared the results of storage and testing under standard conditions of 23 degrees C in dry air, with the results obtained at 37 degrees C in water or plasma.

RESULTS

The dry specimens showed an increase in strength and elastic modulus with time, while the values of the wet ones decreased. There was no difference between specimens stored in water or in plasma. Ultimate compressive strength of dry specimens after 24 h was 1.16 times higher than that of the ones stored wet, increasing to 1.34 times after 1 month, and 1.46 times after 6 months (p<0.001 for all comparisons).

INTERPRETATION

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. The sensitivity of test values to different environments implies that testing conditions for bone cements should be scrutinized in order to develop more relevant testing protocols that reflect the in vivo environment more closely.

Time dependent mechanical properties of bone cement. Anin vitro study over one year

Changes in mechanical properties of bone cements over time are of clinical importance, but not well documented. Specifications for testing do not address the time factor. This study recorded changes in compressive properties and microstructure of one bone cement stored under simulated physiological conditions (water at 37 degrees C) from 20 min up to 1 year and in dry air at 37 degrees C for comparison. Compressive strength increased within the first week (p < 0.001), decreased at 1 month (p < 0.001), and remained at that level at 1 year. Elastic modulus showed a similar development. Maximum strain values, indicating plastic deformability, increased continuously over 1 year. Microscopy revealed microcracks between the pre-polymer beads and the matrix in specimens tested after 20 min, whereas there were less cracks in 1 year specimens. Increase in strength during the first week is due to polymerization and formation of interpenetrating molecular networks. The subsequent decrease could be due to the plasticizing effect of water uptake, as supported by higher values for dry specimens. It can be speculated that microcracks which could be initiated while reducing an arthroplasty at 15 min, acting as initiators for fatigue fractures in the cement mantle, contribute to cement failure. It is recommended that testing of bone cements should be performed after extended ageing at simulated physiological conditions, for the present cement at least 5 weeks. Results obtained at less than one week could be influenced by ongoing polymerization, as well as microcracks and lower coherence between the prepolymer beads and the matrix.

Modelling of non-linear pharmacokinetics in sheep after short-term infusion of cardiotoxic doses of imipramine

Imipramine was administered to sheep (n = 10) by intravenous infusion in high doses (450 mg-900 mg) to elicit cardiovascular shock. A cardiac assist device was then employed to manage the acute overdose situation. The concentration-time course of imipramine and its metabolite desmethylimipramine in plasma was measured by HPLC. As an indicator of imipramine's cardiotoxic effect, cardiac output was monitored. The aim of the study was to evaluate the pharmacokinetics under these conditions and to assess the efficiency of a cardiac assist device with (n = 5) and without (n = 5) an integrated haemoperfusion unit in removing drug from the circulation. The kinetics of imipramine could be described by a three compartment body model with concentration-dependent clearance resulting in non-linear kinetics. The changes in cardiac output with time could be linked to the pharmacokinetic model by a linear relationship. The cardiac assist device was found to contribute to the overall elimination of imipramine whereas the haemoperfusion unit had no clinically relevant impact.