Reconstruction of defects following bone tumor resections by distraction osteogenesis

A probabilistic approach for modelling bone fracture healing under Ilizarov circular fixator

Bone fracture treatments using Ilizarov circular fixator (ICF) involve dealing with uncertainties about a range of critical factors that control the mechanical microenvironment of the fracture site such as ICF configuration, fracture gap size, physiological loading etc. To date, the effects of the uncertainties about these critical factors on the mechanical microenvironment of the fracture site have not been fully understood. The purpose of this study is to tackle this challenge by using computational modelling in conjunction with engineering reliability analysis. Particularly, the effects of uncertainties in fracture gap size (GS), level of weight-bearing (P), ICF wire pretension (T) and wire diameter (WD) on the fracture site mechanical microenvironment at the beginning of the reparative phase of healing was investigated in this study. The results show that the mechanical microenvironment of fracture site stabilised with ICF is very sensitive to the uncertainties in P and GS. For example, an increase in the coefficient of variation of P (COV_P ) from 0.1 to 0.9 (i.e., an increase in the uncertainty in P) could reduce the probability of achieving a favourable mechanical microenvironment within the fracture site (i.e., Probability of Success, PoS) by more than 50%, while an increase in the coefficient of variation of GS (COV_GS ) from 0.1 to 0.9 could decrease PoS by around 30%. In contrast, an increase in the uncertainties in T and WD (COV increase from 0.1 to 0.9) has little influence on the fracture site mechanical microenvironment (PoS changes <5%).

Plate-assisted bone segment transport: Novel application on distal tibia defect after tumour resection. A case report

Introduction

Reconstruction of a large bone defect of the distal tibia after limb salvage surgery is difficult. The options include custom-made ankle endoprosthetic replacement, arthrodesis, and biological or metallic intercalary reconstructions. This report introduces a technique that provides the patient with a long-lasting biological reconstruction while preserving the native ankle.

Presentation of case

We present the case of a 47-year-old man with osteosarcoma of the distal tibia. After neoadjuvant chemotherapy, wide excision was performed while preserving the ankle joint. Bone reconstruction by Plate-assisted bone segment transport (PABST) was performed with a non-invasive growing intramedullary nail. At 34 months of follow-up, there was solid union and the Musculoskeletal Tumour Society Score was 26/30.

Discussion

This is the first report of PABST after distal tibia tumour resection. It shows that this is a viable and safe method of reconstruction. Despite the use of adjuvant chemotherapy, regenerate was formed and union was achieved.

Conclusion

PABST is a useful tool in the armamentarium to tackle difficult large bone defects.

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Large distal tibia bone defects are difficult to manage.

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First report of Plate-assisted bone segment transport after distal tibia tumour resection

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Regenerate was formed and bone union was achieved despite adjuvant chemotherapy.

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Good outcome and function at 34 months of follow-up

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Plate-assisted bone segment transport is a useful reconstructive technique.

Bone fracture healing under Ilizarov fixator: Influence of fixator configuration, fracture geometry, and loading

This study aims to enhance the understanding of the relationship between Ilizarov fixator configuration and its effects on bone fracture healing. Using Taylor spatial frame (TSF) as an example, the roles of critical parameters (ie, TSF ring diameter, wire pre-tension, fracture gap size, and axial load) that govern fracture healing during the early stages were investigated by using computational modelling in conjunction with mechanical testing involving an advanced 3D optical measurement system. The computational model was first validated using the mechanical test results and then used to simulate mesenchymal stem cell (MSC) differentiations within different regions of the fracture site under various combinations of TSF ring diameter, wire pre-tension, fracture gap size, and axial load values. Predicted spatially dependent MSC differentiation patterns and the influence of each parameter on differentiations were compared with in vivo results, and good agreement was seen between the two. Gap size was identified as the most influential parameter in MSC differentiation, and the influence of axial loading and TSF configuration (ie, ring diameter and wire pre-tension) on cell differentiation was seen to be gap size dependent. Most changes in cell differentiation were predicted in the external callus (periosteal), which is the crucial region of the callus in the early stages. However, for small gap sizes (eg, 1 mm), significant changes were predicted in the endosteal callus as well. The study exhibits the potential of computational models in assessing the performance of Ilizarov fixators as well as assisting surgeons in patient-specific clinical treatment planning.

Nerve Regeneration and Functional Recovery With Neurorrhaphy Performed at the Early Distraction Osteogenesis: An Experimental Study

Distraction osteogenesis is widely used in many clinical situations, but distraction in cases accompanying nerve injury has been avoided due to concern of unfavorable effect on nerve regeneration by traction. This study evaluated the feasibility of early distraction lengthening after neurorrhaphy. Thirty-six rats were evenly distributed into 3 groups (12 rats in each group); neurorrhaphy and distraction (group I), neurorrhaphy and osteotomy without distraction (group II), and only distraction without neurorrhaphy (group III), respectively. After osteotomy on the right tibia, distraction started after 1 week and was continued for 40 days with 0.25 mm per day. Histological evaluation was carried out to identify nerve regeneration at 4, 8, and 12 weeks after surgery. Walking tract analysis was performed to assess the functional recovery preoperatively and 1, 4, 8, and 12 weeks postoperatively. Histologically, axon number ratio was significantly impaired in group I (0.48 ± 0.14) and group II (0.53 ± 0.13) compared with group III (0.88 ± 0.04) at 4 weeks (P = 0.020). There was no significant difference at both 8 and 12 weeks. Walking tract analysis showed significant differences between groups I and III (-40.5 ± 4.3), and groups II and III (-35.5 ± 5.0) at 1 week (P = 0.001), but no difference was observed at 8 and 12 weeks. Distraction osteogenesis in early stage after nerve repair is safe and effective, when performed at a rate of 0.25 mm per day in rats.

Distraction osteogenesis and arthrodesis as a new surgical option for chondrosarcoma in the distal tibia

Recent advances in the management of bone tumors have led to a significant increase in the survival rates of patients with malignant bone tumors. Thus, limb salvage surgery has gained importance for preserving limb function in the management of bone tumors. However, surgery presents unique difficulties in terms of the biomechanics and obtaining a soft-tissue cover, such as when the ankle is involved in the primary malignant bone tumor. We report a case of chondrosarcoma of the distal tibia treated with wide en bloc resection arthrodesis and reconstruction of the defect using distraction osteogenesis, which offers an effective alternative protocol for limb salvage. The patient has remained disease free for 3 years since the initial surgery and can maintain normal limb athletic function.

Limb salvage: When, where, and how?

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

Reconstruction of intercalary bone defects following bone tumor resection with segmental bone transport using an Ilizarov circular external fixator

AIM

The purpose of this retrospective study was to report the long-term follow-up results of the reconstruction of bony defects with Ilizarov distraction osteogenesis using the bone transport method following en bloc resection of bone tumors.

MATERIALS AND METHODS

En bloc resection was performed in 13 patients with bone tumors between October 1991 and December 2010 in our clinic. The mean age of the patients was 19.46 years (range 7-42 years) at the time of surgery. Histological diagnosis was osteosarcoma in seven cases, Ewing's sarcoma in three cases, giant cell tumor in one case, osteoblastoma in one case and fibrous dysplasia in one case. In all cases either the femur or tibia was involved.

RESULTS

The average follow-up period was 157.23 months (range 32-288 months), and the bone defect after resection was 14.61 cm ± (9-24 cm). The mean Musculoskeletal Tumor Society score of the patients was 89.46 (83-96) at the final follow-up. The mean Knee Society Scale scores of patients in whom reconstruction was performed around the knee joint were 74.3 (51-84). The mean foot and ankle disability index of patients with a tumor around the ankle joint was 81 (73-95). Quality of life of the patients according to the SF-36 and BQUILI indexes was scored as 104 (88-150) and 4 (0-13), respectively.

CONCLUSION

From the long-term follow-up results, reconstruction with distraction osteogenesis seems to be an efficient method in patients with long life expectancies. However, a long external fixation time is a disadvantage of this technique. Problems in patient compliance and possible complications such as nonunion should be managed promptly.

Limb salvage in musculoskeletal oncology: Recent advances

The treatment of musculoskeletal sarcomas has made vast strides in the last few decades. From an era where amputation was the only option to the current day function preserving resections and complex reconstructions has been a major advance. The objectives of extremity reconstruction after oncologic resection include providing skeletal stability where necessary, adequate wound coverage to allow early subsequent adjuvant therapy, optimising the aesthetic outcome and preservation of functional capability with early return to function. This article highlights the concepts of surgical margins in oncology, discusses the principles governing safe surgical resection in these tumors and summarises the current modalities and recent developments relevant to reconstruction after limb salvage. The rationale of choice of a particular resection modality, the unique challenges of reconstruction in skeletally immature individuals and the impact of adjuvant modalities like chemotherapy and radiotherapy on surgical outcomes are also discussed.

Outcome of expandable prostheses in children

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

The outcome of the treatment of diaphyseal primary bone sarcoma by resection, irradiation and re-implantation of the host bone

We analysed the outcome of patients with primary non-metastatic diaphyseal sarcomas who had en bloc resection with preservation of the adjoining joints and reconstruction with re-implantation of sterilised tumour bone after extracorporeal radiation (50 Gy). Between March 2005 and September 2009, 32 patients (16 Ewing’s sarcoma and 16 osteogenic sarcoma) with a mean age of 15 years (2 to 35) underwent this procedure. The femur was the most common site in 17 patients, followed by the tibia in 11, humerus in three and ulna in one. The mean resected length of bone was 19 cm (10 to 26). A total of 31 patients were available at a mean follow-up of 34 months (12 to 74). The mean time to union for all osteotomy sites was 7.3 months (3 to 28): metaphyseal osteotomy sites united quicker than diaphyseal osteotomy sites (5.8 months (3 to 10) versus 9.5 months (4 to 28)). There were three local recurrences, all in soft-tissue away from irradiated graft. At the time of final follow-up, 19 patients were free of disease, one was alive with disease and 11 had died of disease. The mean Musculoskeletal Tumor Society Score for 29 patients evaluated at the last follow-up was 26 (9 to 30).

Extracorporeal irradiation is an oncologically safe and inexpensive technique for limb salvage in diaphyseal sarcomas and has good functional results.

Overlapping allograft in reconstructive surgery for malignant bone tumours in paediatric patients

The use of allografts for the treatment of bone tumours in children is limited by nonunion and the difficulty of finding a suitable graft. Furthermore, appositional growth can’t be expected of an allograft.

We used an overlapping allograft in 11 children, with a mean age of ten years (4 to 15), with a mean follow-up of 24.1 months (20 to 33). There were five intercalary and six intra-articular resections, and the tumours were in the femur in six cases and the humerus in five. Rates of union, times to union, remodelling patterns and allograft-associated complications were evaluated.

No allograft was removed due to a complication. Of the 16 junctional sites, 15 (94%) showed union at a mean of 3.1 months (2 to 5). Remodelling between host and allograft was seen at 14 junctions at a mean of five months (4 to 7). The mean Musculoskeletal Tumor Society score was 26.5 of 30 (88.3%). One case of nonunion and another with screw protrusion required re-operation.

Overlapping allografts have the potential to shorten time to union, decrease rates of nonunion and have positive appositional growth effect.

Extracorporeal irradiated tumor bone: A reconstruction option in diaphyseal Ewing's sarcomas

BACKGROUND

Limb salvage in extremity tumors is now established as an oncologically safe option without compromising long-term survival. En bloc resection followed by extracorporeal radiation and reimplantation is a biological reconstruction option in diaphyseal Ewing's sarcomas. We analyzed the results of 12 cases of diaphyseal Ewing's sarcomas treated using this modality.

MATERIALS AND METHODS

Between March 2006 and March 2008, 12 patients with Ewing's sarcoma underwent enbloc resection and reconstruction, with reimplantation of the sterilized tumor bone, after extracorporeal irradiation. There were eight males and four females, with a mean age of 14 years (range 2 to 22 years). The femur was the most common bone involved (n=8) followed by the tibia and the humerus (two cases each). All these patients were non-metastatic at presentation and received chemotherapy as per the existing hospital protocol. The mean length of the bone resected was 20 cm (range 11 to 25 cm). The specimen was irradiated with 50 Gy prior to reimplantation and stabilized with the host bone, using suitable internal fixation. Standard biplanar radiographs were assessed for evidence of union on the follow-up visits. The functional status was assessed using the Musculoskeletal Tumor Society Scoring system at the time of the last follow up. The mean follow up duration was 29 months (range 12 to 57 months).

RESULTS

Two patients (17%) had early infection with graft removal, hence are excluded from any analysis of union, however they are included when analysing complications such as infection. Rest 10 cases were analyzed for bony union at the osteotomy sites. Sixteen (84%) of the 19 osteotomy sites united primarily, without any intervention. Implant failure and non-union was seen at three diaphyseal osteotomy sites. The average time for union of all osteotomy sites was 7.2 months (range 3 to 13 months).The average time for union of the metaphyseal osteotomy sites was 5.9 months (range 3 to 12 months) and of diaphyseal osteotomy sites was 8.3 months (range 4 to 13 months). The mean Musculoskeletal Tumor Society Score was 27 (range 19 to 30) with a mean of 27. Nine of the ten patients with lower limb involvement were independent ambulators without additional aids. At the time of the last review, six patients were free of disease and six patients had died from the disease. There were two recurrences around the operative site. Both were associated with disseminated disease and in both the recurrences were in the soft tissue, away from the irradiated graft.

CONCLUSION

Extracorporeal irradiation is a useful, convenient technique for limb salvage in diaphyseal Ewing's sarcomas when there is reasonable residual bone stock. It is oncologically safe and has good functional results. A radiation dose of 50 Gy for sterilizing the bone ensures adequate tumor kill, while minimizing the deleterious effects on the biomechanical and biological properties of the bone. The use of appropriate implants for adequate internal fixation and supplementary bone grafting at the index surgery may help reduce the need for subsequent additional interventions to achieve union. The limitations of this procedure are that it is not applicable in tumor bones that are structurally weak and in bones with pathological fractures.

Adamantinoma of the tibia mimicking a benign cystic lesion: a case report

Adamantinoma of the long bones is a rare primary malignant bone tumor accounting for less than 1% of all primary malignant bone tumors. Most typical imaging findings include heterogeneous osteolytic cortical lesions showing multiple sharply circumscribed lucent zones of various sizes with sclerotic bone surroundings, interspersing between, and extending above and below the lucent zones by the thinning and bulging cortex. Advanced or recurrent lesions may be associated with destruction of the cortex and soft tissue extension. In this article, the authors present a case report of a patient with a distal tibia adamantinoma mimicking a benign cystic lesion.

Methods of biological reconstruction for bone sarcoma: indications and limits

Therapy of bone sarcoma has dramatically changed over the past few decades. Several successful interdisciplinary treatment strategies have led to an increase of the survival rates from 20% to 60%-80%. Consequently new demands on the operative treatment of bone and soft tissue sarcoma have arisen. Nowadays limb salvage can be achieved in 80%-90% using tumour megaprostheses or biological reconstruction procedures. In this article we outline the indications and limitations of biological reconstruction procedures after bone tumour resection. We therefore introduce the different biological approaches such as free autologous bone grafting, reimplantation of extracorporeal devitalized autografts or distraction osteogenesis and summarize the currently available data on the individual procedures. Our analyses demonstrate a wide applicability of biological procedures in tumour situations. Although accompanied by considerable complications in the early postoperative phase, biological reconstructions clearly demonstrate the potential of having excellent long-term durability and functionality.

Surgical management of primary osteosarcoma

Surgical strategies for the primary tumor for patients with extremity and pelvis osteosarcoma have evolved from the ablative to limb-sparing approaches over the past three decades. Favorable oncologic and functional outcomes with contemporary tissue-conserving techniques consistently observed in skeletally mature patients have prompted the application of similar approaches to a growing number of eligible skeletally immature patients. In response to emerging long-term outcome data, current strategies have focused principally on refining the nature and scope of surgical resection to preserve uninvolved tissues, and on the adoption of novel biological and nonbiological skeletal and soft-tissue reconstruction methods to optimize function. We focus on these clinical issues and discuss current efforts to advance the surgical management of the primary tumor and address the limitations of the definitive treatment of the primary tumor, including locally recurrent disease and complications of skeletal reconstructions.

Safety of external fixation during postoperative chemotherapy

We studied the safety of external fixation during post-operative chemotherapy in 28 patients who had undergone distraction osteogenesis (17, group A) or vascularised fibular grafting (11, group B) after resection of a tumour. Four cycles of multi-agent post-operative chemotherapy were administered over a mean period of 14 weeks (6 to 27). The mean duration of external fixation for all patients was 350 days (91 to 828). In total 204 wires and 240 half pins were used.

During the period of post-operative chemotherapy, 14 patients (11 in group A, 3 in group B) developed wire- and pin-track infection. A total of ten wires (4.9%) and 11 half pins (4.6%) became infected. Seven of the ten infected wires were in periarticular locations.

External fixation during post-operative chemotherapy was used safely and successfully for fixation of a vascularised fibular graft and distraction osteogenesis in 27 of 28 patients. Post-operative chemotherapy for malignant bone tumours did not adversely affect the ability to achieve union or cause hypertrophy of the vascularised fibular graft and had a minimal effect on distraction osteogenesis. Only one patient developed osteomyelitis which required further surgery.

Treatment of osteofibrous dysplasia and associated lesions

PURPOSE

To report long term treatment outcomes of osteofibrous dysplasia and association with adamantinoma.

PATIENTS AND METHODS

From January 1984 to July 2001, 14 patients with osteofibrous dysplasia were followed for an average of 108 months (78 to 260 months). Our patient group consisted of 6 men and 8 women, with a mean age of 13.9 years (2 to 65 years). We reviewed the clinical and pathological features of all 14 patients.

RESULTS

Thirteen patients had a lesion in the tibia, while one patient had lesions in both the tibia and the fibula. Initial treatments were observation after biopsy (6 patients), curettage with or without a bone graft (3 patients), resection followed by a free vascularized fibular bone graft (4 patients), or resection and regeneration with the Ilizarov external fixation (1 patient). Curettage was performed on 6 patients due to recurrence or progression after the initial treatment. Among these patients, one was diagnosed with AD from the biopsy of the recurrent lesion. This patient was further treated by segmental resection and pasteurization. After the initial pathology slides of the 13 patients were reviewed with immunohistochemical cytokeratin staining, one patient diagnosis was changed from osteofibrous dysplasia to osteofibrous dysplasia-like adamantinoma.

CONCLUSION

Some patients with osteofibrous dysplasia require close observation because of the high association risk between osteofibrous dysplasia and adamantinoma, Immunohistochemical staining may be helpful in differentiating these two diagnoses.

Pasteurized autograft for intercalary reconstruction: an alternative to allograft

Intercalary resection and reconstruction for tumors have become increasingly popular. We asked whether pasteurized autologous bone graft was comparable to other reported reconstruction methods regarding union rates, complications, and functional outcomes. We retrospectively analyzed the outcome of 21 intercalary pasteurized bones in lower extremities. Ultimate graft survival, union rate, and union time were evaluated as a function of clinical variables, such as age, gender, body mass index, location of intercalary segment, primary tumor type, use of chemotherapy, percentage and length of resected bone, type of junction, method of fixation, and iliac bone graft at index operation. The overall survival rate of pasteurized bone was 74% at 10 years. We identified no clinical variables associated with graft survival or union time. The union rate was related to length or percentage of resected segment and location of osteotomy. The rates of infection, fracture, and nonunion were three of 21, two of 21, and five of 21, respectively. Our results suggest reconstruction with pasteurized autograft is a simple and easily accessible method in limb salvage and an economic alternative to allograft, with low rates of ultimate failure and graft-related complications.

Bioabsorbable scaffold for in situ bone regeneration

A non-porous poly-DL-lactide tubular chamber filled by demineralised bone matrix (DBM) and bone marrow stromal cells (BMSC) in combination, was evaluated as a scaffold for guided bone regeneration (GBR) in an experimental model using the rabbit radius. The tubular chamber had an internal diameter of 4.7 mm, a wall thickness of 0.4 mm and a length of 18 mm. Autologous BMSC were obtained, under general anaesthesia from rabbit iliac crest and isolated by centrifugation technique. Allogenic DBM was obtained from cortico-cancellous bone of rabbits. In general anaesthesia, a 10-mm defect was bilaterally created in the radii of 10 rabbits. On the right side (experimental side) the defect was bridged with the chamber filled with both BMSC and DBM. On the left side (control side) the defect was treated by positioning DBM and BMSC between the two stumps. At an experimental time of 4 months histology and histomorphometry demonstrated that the presence of a tubular chamber significantly improved bone regrowth in the defect The mean thickness of newly-formed bone inside the chamber was about 56.7+/-3.74% of the normal radial cortex, in comparison with 46.7+/-10.7% when DBM and BMSC without the chamber were placed in the defect, P<0.05). These results confirmed the effectiveness of the chamber as a container for factors promoting bone regeneration.

Surgical options and outcomes in bone sarcoma

Bone sarcomas are challenging to treat. The primary goal of treatment is local control of the disease while, if possible, achieving salvage of the limb and its function. There is no ideal method of reconstruction in limb-salvage surgery but the choice of the method of reconstruction should be individualized based upon many factors including the patient's age, the extent and location of the tumor, the wishes of the patient, and the availability of surgical facilities and expertise, as well as the cost of the procedure. In this review, the authors explore the advantages and disadvantages of the different methods of limb reconstruction. The surgical management of bone sarcomas is a real challenge to the orthopedic surgeon, owing to the diversity of sites in which tumors arise, combined with the extension of the tumor into adjacent soft tissues and their proximity, in many cases, to major neurovascular structures. There have been dramatic improvements in survival for patients with osteosarcoma and Ewing's sarcoma in the past 30 years owing to increasing effectiveness of chemotherapy. This, along with developments in imaging techniques (magnetic resonance imaging in particular) has led to earlier diagnosis and more accurate preoperative staging. Whilst traditional treatment for bone tumors used to be amputation, advances in surgical techniques have made limb-salvage procedures a valid alternative method of treatment to amputation in 80-85% of patients with primary bone sarcomas.