Osteosarcoma used to be a fatal malignancy of the bone, causing death in more than 80% of patients within 5 years of diagnosis. With increased awareness of the disease, treatment options are now available to cure approximately 70% of patients with primary limb tumors without metastatic manifestations. Classically, osteosarcoma is defined as a highly malignant spindle cell sarcoma that produces a bone-like stroma. Approximately 900 cases of osteosarcoma are diagnosed annually throughout the United States, and it is the most common primary malignancy of bone other than multiple myeloma. The incidence of osteosarcoma is approximately 3/10,000 in the U.S. There are more than 10,000 registered cases in the osteosarcoma database, and the Massachusetts General Hospital (MGH) Oncology Center has diagnosed 670 such cases since 1972.
Osteosarcoma is more common in male patients and predominantly occurs in the second decade of life, with a second peak of prevalence in late adulthood, primarily due to osteosarcoma associated with Paget’s disease. The cause of osteosarcoma is not known (as is the case with most other bone tumors). When a family member has osteosarcoma, consideration should be given to whether there is a genetic component. Patients with hereditary retinoblastoma and Li-Fraumeni syndrome are more likely to have osteosarcoma as a complication. Evidence for virus-induced osteosarcoma lies in animal studies demonstrating that specific viruses can induce various sarcomas of bone in selected animals. Radiation-induced osteosarcomas account for 3% of the total and are most often seen in patients with other types of tumors treated with radiation therapy and alkylating agents. The risk of secondary bone tumors is seen in the fact that increasing the dose of drugs and the use of alkylating agents in chemotherapy regimens can potentially enhance the radiation effect and thus secondary osteosarcoma. The application of radiotherapy to invaded bone is more likely to produce secondary sarcomas than other tissues.
The predilection for fast-growing tumors and the age of the patient suggest that the pathology of this tumor is closely related to bone growth and development. Osteosarcomas occur in the epiphyseal segment of long bones. The most common sites are the distal femur, proximal tibia and humerus, which are the fastest growing areas in adolescents. The flat bones are less commonly involved. In the study of the MGH patient group, the most common site was the knee (of which the distal femur, 32%; proximal tibia, 16%).
Highly malignant osteosarcoma should be recognized as a systemic disease, as most have microscopic metastases present by the time the diagnosis is made. Patients without metastases who develop new pulmonary metastases one year or more after chemotherapy and surgical resection have a better prognosis than those who have pulmonary metastases at the time of diagnosis. Approximately 10-20% of patients with osteosarcoma have imaging of metastases at diagnosis, and these patients are classified as stage III osteosarcoma according to the Musculoskeletal Tumor Society (MSTS) staging criteria. The majority of patients (73%) with osteosarcoma in MGH have MSTS stage IIB tumors, and 12% have distant metastases. The sites of these metastases are often detected by chest CT scans and whole-body bone scans. Sites of metastases include the lungs, followed by bone and, more rarely, other internal organs such as the pleura, pericardium, kidneys, adrenals, lymph nodes and brain. A small number of patients have bone and lung metastases, and most deaths from metastases are due to failure of control of pulmonary lesions, such as extensive metastases in the lungs, intrapulmonary hemorrhage, pneumothorax, or obstruction of the vena cava. The vast majority of patients who die from metastases have pulmonary involvement at the time of death.
Clinical Presentation
Patients usually have pain and localized soft tissue masses. Symptoms can be present for 3 months or longer and begin after a single injury. Trauma is not considered to be a predisposing factor for tumors, although many researchers have attempted to demonstrate that microfractures following trauma can induce tumor formation. Symptoms can be mild and severe, making diagnosis difficult. The accompanying pain is constant and progressively worse. The pain may be present at rest or at night and is not associated with activity. There are often no systemic symptoms. The most important physical examination finding is the presence of a soft tissue mass. Soft tissue masses vary greatly in size, but are usually quite large and palpable. There may be intra-articular oozing or pathologic fractures. Specific laboratory tests are often abnormal, such as alkaline phosphatase or lactate dehydrogenase levels, both of which can be elevated at the time of diagnosis. Abnormal elevations, especially of lactate dehydrogenase, often suggest a poor prognosis.
Imaging manifestations
In most cases, imaging findings and clinical information can help predict the pathologic diagnosis of the tumor. The typical imaging presentation of osteosarcoma shows an aggressive lesion located in the long bone epiphysis. The tumor disrupts the normal trabecular architecture with poorly defined borders and without any visible bone reaction of the endosteum. Radiographic high-density osteogenic areas mixed with low-density osteolytic areas were evident. Periosteal new bone forms and rises above the cortical surface with Codman’s triangular formation and “starburst” appearance. The associated soft tissue mass has varying degrees of ossification, depending on the extent of osteogenic and chondrogenic areas. (Fig.1)
Pathological presentation
Osteosarcoma is classically defined as a group of tumors that produce neoplastic bone-like tissue or bone directly from a highly malignant sarcomatoid stroma and malignant osteoblasts. Tumors often appear to have a central mineralization surrounded by immature, lacking mineralized bone tissue, and tumor cells often appear to be mesenchymal with heterogeneous nuclei and double attachment sites. The tumor may have areas of differentiation to chondrocytes or fibroblasts, but the presence of small areas of tumor bone like stroma is sufficient for the diagnosis of osteosarcoma. (Figs. 2,3)
Tumor staging
The staging of osteosarcoma is the same as for other highly malignant sarcomas. A thorough histologic and physical examination is required. Hematologic studies, including lactate dehydrogenase and alkaline phosphatase levels, are required. In addition, plain radiographs of the bone and chest at the site of the lesion, a whole-body bone scan, a CT scan of the chest, and a local MRI, which may be the most important test to determine whether limb-sparing surgery can be performed or if amputation is necessary to achieve local control, are required. The coronal T1 phase shows the extent of intramedullary invasion of the tumor. The entire bone needs to be scanned to exclude jumping metastases within the bone. The joints need to be carefully evaluated for tumor invasion. Dynamic imaging after administration of enhanced contrast (gadolinium) is useful to understand the extent of tumor necrosis after preoperative chemotherapy.
Classification of tumors
This section focuses on the classic, highly malignant, central type of osteosarcoma, but there are several other types. Osteosarcomas can be classified into a number of different subtypes depending on the grade of malignancy, the number of tumor sites, the location of the tumor in the bone, and the cause of the disease. Superficial osteosarcoma can be histologically graded as highly, intermediate, or less malignant.
Parosteal osteosarcoma
The typical parosteal osteosarcoma presents as a collection of histologically low-grade malignant fibroblasts that produce woven or laminated osteogenesis. The age of onset is older than typical osteosarcoma and is most often seen between the ages of 20-40 years. The posterior aspect of the distal femur is the most common site of parosteal osteosarcoma, and other long bones can also be invaded. The tumor is an extensive basal lesion originating from the cortical bone. The tumor may invade the cortical bone into the medullary cavity in the later stages of the lesion. Treatment is based on surgical resection, with a survival rate of 80-90%. (Fig.4)
Periosteal osteosarcoma
Periosteal osteosarcoma is a moderately malignant chondrocyte-derived surface bone lesion that occurs in the proximal tibia. The age of onset is the same as that of classic osteosarcoma. Metastasis occurs more frequently than in the less malignant paracortical tumors but less frequently than in the classic central osteosarcoma. The role of adjuvant chemotherapy in periosteal osteosarcoma is not clear, but because of the approximately 20% chance of metastasis, it is used in most oncology centers.
Highly malignant superficial osteosarcoma (paracortical osteosarcoma)
Conventional highly malignant osteosarcoma can also occur on the surface of the bone and can be confused with parosteal or periosteal osteosarcoma. Treatment is the same as for conventional osteosarcoma. (Fig.5)
Secondary osteosarcoma
Secondary osteosarcoma occurs in patients with Paget’s disease and prior radiation therapy. Secondary osteosarcoma is rarely seen in patients with poor fibrous architecture who have not been treated with radiation.
Multicentric osteosarcoma
This type of osteosarcoma is rare, but sometimes patients are diagnosed with multiple sites of tumor lesions that present similarly to the primary tumor. It is difficult to determine if these sarcomas originate from multiple sites or if they should be considered metastases. In all such cases, the prognosis is poor. Multicentric osteosarcoma can also occur in other parts of the bone within a few years after treatment of the first lesion.
Capillary osteosarcoma
Capillary osteosarcoma appears on plain radiographs as an osteolytic lesion with a small amount of calcification or tumor bone formation. It is easily confused on imaging with many benign lesions, such as aneurysmal bone cysts. This is a highly malignant, vascular damage accompanied by a small amount of bone-like tissue production tumor. The age distribution of patients and principles of treatment are the same as for other classic, highly malignant osteosarcomas. Although capillary dilated osteosarcoma is considered a more aggressive type, its response to adjuvant chemotherapy is similar to other types of conventional osteosarcoma. Obtaining the tissue needed for a pathologic diagnosis by puncture biopsy is often difficult because it usually presents as multi-cystic tumor tissue that is rich in blood vessels and lacks solid areas.
Prognostic factors
The extent of tumor invasion is very important in indicating prognosis, and patients with metastatic lesions have a poor prognosis. The presence of metastases is an extremely poor prognostic factor and there is little chance of long-term survival if the patient is not treated surgically to remove the lesions. Treatment for the presence of metastases is necessary to improve the patient’s prognosis. Treatment includes removal of the metastases from the lungs if possible and adjustment of the chemotherapy regimen. Sometimes, radiation therapy for metastases is indicated.
The location of the primary tumor is also an important prognostic factor, as tumors in the medial bones and proximal extremities have a poorer prognosis. The size of the tumor is considered an important prognostic factor. Jumping metastases, which refer to another lesion in the same bone as the primary lesion, are an indication of poor prognosis in the same way as pulmonary metastases. Pathological fractures at the time of diagnosis are also poor prognostic factors.
The assessment of histological necrosis rates in surgically resected specimens after chemotherapy is a prognostic factor for the effect of drug response noted in many studies. Poor responders (often defined as a necrosis rate of less than 95%) are more likely to develop distant metastases, and metastases are more likely to occur regardless of whether postoperative chemotherapy is continued than those with a necrosis rate greater than 95%. The response rate of the primary tumor to chemotherapy as a prognostic factor has been confirmed by the results of several studies. Multiple assessment systems have been used to evaluate necrosis rates in surgically resected tumor specimens that have undergone preoperative chemotherapy. Nowadays, most consider a satisfactory response rate as a necrosis rate of >98% of the primary tumor, while an unsatisfactory situation is the presence of surviving tumor tissue. Most, but not all, patients have a good prognosis when they have a good response rate, whereas metastases often develop when the histologic response rate is unsatisfactory after preoperative chemotherapy. Histologic grading of chemotherapy response provides a way to discern early in the treatment process whether a patient is at high risk for recurrence. The original intent was to add new drugs for salvage therapy in patients with poor chemotherapy response, and although this aspiration has not yet been realized, it is an area that warrants continued research.
Treatment
Chemotherapy
Treatment of patients with osteosarcoma includes complete, extensive resection or amputation of the primary tumor, and systemic adjuvant chemotherapy. The use of systemic adjuvant chemotherapy has led to a significant improvement in the prognosis of patients with osteosarcoma (see Chapter 18 on adjuvant chemotherapy for osteosarcoma). Early studies concluded that chemotherapy was effective for micro-metastases, so it was applied after amputation. Regimens included adriamycin, high-dose methotrexate, cisplatin, and several other agents, and several studies showed an increase in disease-free survival from 10-20% with no chemotherapy to 50-65%. Although the benefits of chemotherapy were not widely accepted initially, a randomized study comparing immediate postoperative adjuvant chemotherapy with delayed chemotherapy (applied only in patients presenting with metastases) was undertaken. The results and other studies clearly showed better disease-free survival and overall survival in the experimental group treated with adjuvant chemotherapy.
Recent research has focused on the application of preoperative chemotherapy (neoadjuvant chemotherapy) prior to resection of the tumor. This approach has several advantages, such as the ability to determine prognosis based on the tissue response rate obtained, reducing the size of the tumor to make surgery easier to perform, increasing tumor necrosis, and possibly making limb-sparing surgery safer in the opinion of some surgeons. For these reasons neoadjuvant chemotherapy has become the standard chemotherapy regimen in most oncology centers. Nevertheless, there are some potential drawbacks, including the possibility that some patients may not respond well to chemotherapy and will have an increase in drug-resistant tumor cells. A study by the Pediatric Oncology Group showed that preoperative chemotherapy did not have an advantage over postoperative chemotherapy in terms of overall survival and disease-free survival. This study has not received sufficient attention. Another study by the Pediatric Oncology Study Group and the Children’s Cancer Group suggested that adding isocyclophosphamide and/or immunostimulant (MTP-PE) to a regimen of adriamycin, high-dose MTX, and cisplatin was effective in improving survival; the results of this study have not been published.
Regardless of improvements in chemotherapy regimens, 20-40% of patients still eventually die from osteosarcoma. Recent studies have confirmed the mechanism by which some tumors become resistant to seemingly effective treatments. One of the main reasons for this is the emergence of resistance to chemotherapeutic agents, which makes them ineffective against tumor cells. There are several mechanisms by which multidrug resistance occurs in osteosarcoma, one of which is P-glycoprotein, a membrane-bound glycoprotein encoded by the MDR-1 (multidrug resistance) gene that is expressed in a variety of tumors and normal tissues. It is an adenosine triphosphate-dependent membrane transporter glycoprotein that is able to pump different classifications of drugs, such as adriamycin, out of the cell. There is speculation that the main reason for poor response to chemotherapy is the presence of P-glycoprotein; several current studies have shown that patients with tumors expressing P-glycoprotein have significantly lower disease-free and overall survival rates than patients whose P-glycoprotein expression cannot be measured in the tumor. In one study, P-glycoprotein expression was not correlated with tissue necrosis rates and was a more important prognostic factor than tumor necrosis rates.MDR reversal agents, which block P-glycoprotein function, can allow drug accumulation within cells to overcome its side effects. Unfortunately, the toxicity of current reversal agents is significant, and their role in other tumor studies is not significant; however, overcoming drug resistance is an area worthy of current research focus. Identifying chemotherapy “nullifiers” and providing them with individual therapy to avoid unnecessary drug toxicity may improve prognosis.
Surgery
Preoperative chemotherapy is thought to increase the likelihood of limb-sparing surgery and to make it easier to perform because of the reduced size of the tumor. However, until today, there has not been a randomized study to support this idea and osteosarcoma is less likely to see a reduction in tumor volume after neoadjuvant chemotherapy due to its stromal composition, although mineralization within the tumor is seen. Despite this, the vast majority of surgeons believe that resection of primary osteosarcoma after chemotherapy is safer from an oncologic point of view. a study by the Rizzoli Institute demonstrated a relationship between surgical boundaries and response to chemotherapy (tumor necrosis rate) and the risk of local recurrence. The risk of local recurrence was increased when patients failed to achieve extensive resection and failed to achieve a good response to chemotherapy. In contrast, a recent unpublished long-term study by the Children’s Oncology Study Group (DJ Schwartzenruber, MD, AM Goorin, MD, MC Gebhardt, MD, et al, Washington, DC, unpublished data, 1999) showed that limb-sparing surgery in patients who did not undergo preoperative chemotherapy also resulted in an increased risk of local recurrence. The results of the study (Washington, DC, unpublished data, 1999) showed that good local control of the tumor can be achieved with limb-sparing surgery in patients who have not undergone preoperative chemotherapy. The vast majority of research centers now use preoperative chemotherapy to treat patients who are ready to undergo limb-sparing surgery.
Improved reconstructive techniques and the increasing experience and confidence of oncologic surgeons have led to an increase in the number of limb-sparing surgeries. Today, approximately 80% of patients with osteosarcoma of the limb undergo limb-sparing surgery. Achieving a negative border of normal tissue around the tumor is an important surgical principle, but we do not know exactly the thickness of normal tissue required, and many specimens have at least one surgical area adjacent to the margin of resection. What we need to know is that limb function after lower limb amputation is often excellent, especially in children. Adequate local control is often not guaranteed in limb-preserving surgery, and local recurrence is often fatal. When extensive surgical resection boundaries can be achieved, disease-free and overall survival rates are the same with amputation and limb-preserving surgery, a finding that has been demonstrated in retrospective studies on osteosarcoma of the distal femur.
It is important to select the right patient for limb-preserving surgery. The chosen surgical procedure should not defeat the purpose of oncologic treatment. Although some investigators have reported that healing of pathologic fractures can be achieved with chemotherapy to facilitate the performance of limb-sparing surgery, pathologic fractures may still be a contraindication to limb-sparing surgery. There are not a large number of studies on the implementation of limb-sparing surgery in patients with pathological fractures, and the majority of investigators usually choose amputation over limb-sparing surgery because of the unacceptably high local recurrence rate associated with overly conservative local treatment. Also, patients presenting with pathologic fractures have a higher incidence of secondary systemic metastases. Nevertheless, patients with fractures without displacement may be candidates for local excision if they have a good response to chemotherapy.
Specific sites, such as the proximal tibia, are more difficult to perform limb-sparing resections because of the difficulty in achieving adequate soft tissue resection boundaries. Similarly, limb-sparing surgery of the lower extremity is not appropriate for very young, underdeveloped patients. This would result in future inequality of the lower extremity, although this could be made relatively contraindicated by artificial joint fabrication. Advances in surgical techniques have made more patients suitable for limb-sparing surgery, and several new techniques are being used to repair residual defects after tumor bone resection. We will briefly touch upon several of these.
Sacrificable bone, such as the ulna, fibula, scapula, and ribs, do not require bone reconstruction after resection. The surgical approach to osteosarcoma in these areas has been well described, and minimal functional impairment occurs postoperatively. Surgical resection of osteosarcoma of the pelvis is complex and the details will not be discussed here. The surgical approach is either a hemipelvic resection or an internal hemipelvic resection. Reconstruction is not required for removal of the iliac or pubic branches, whereas if the acetabulum is involved, function will be significantly compromised after resection. Reconstruction requires an allograft or saddle joint, but its postoperative complication rate is relatively high and postoperative function is often suboptimal. Many surgeons prefer to form a pseudo-joint between the proximal femur and the remaining pelvic bone or sacrum, especially when a large amount of soft tissue has been removed. Fortunately, osteosarcomas of the spine and sacrum are rare and require individualized treatment with a combination of surgery, chemotherapy, and radiation therapy.
The vast majority of osteosarcoma conservations require repair of the structural integrity of the shoulder or knee joint. Clinical experience has focused on the use of biomaterials and metallic joint devices. Both approaches have their advantages and disadvantages, and there are no convincing comparative studies on which approach is better. Allograft bone reconstruction can provide reconstructed joint surfaces, ligaments, and tendon attachment points. A prosthesis can provide immediate joint stability and mechanical fixation, thus allowing for early ambulation and use. The choice of the appropriate procedure for a specific patient depends on the patient’s age, the defect to be repaired and the preference of the operator and the patient themselves.
Proximal humeral upper extremity function should be preserved whenever possible. In most cases, an intra- or extra-articular resection that preserves the normal tissue surrounding the tumor can be performed. This often means loss of the deltoid muscle and some or all of the rotator cuff tendons. The scapular glenoid or part of the scapula may need to be resected, depending entirely on the extent of the lesion invasion. If the entire scapula is removed (called a Tikhoff-Linberg resection), the result is still better than amputation as long as the vascular nerve bundle and normal hand function are preserved.
Reconstruction methods after intra-articular resection include allograft bone, metal prosthesis, or allograft bone-prosthesis composite joints. The advantage of allograft bone is that it provides attachment points for rotator cuff muscles and other muscles; however, allograft bone has a higher complication rate. A recent study of 16 patients showed a 70% functional score and preserved manual dexterity, but also a significant loss of shoulder function, inability to perform sports activities, dislocation/subluxation, infection, and a higher incidence of fracture. These authors no longer use this method for reconstruction, but some centers continue to do so. Metal prostheses are more durable, but the reconstructive repair of soft tissues is limited and the rotator cuff is poorly functional. A follow-up study on a large sample of prosthetic reconstructions showed that the proximal humerus had the best function (26 out of 30 on the MSTS scoring system) and the lowest rate of local complications compared to other sites. The revision rate was 10% (3 of 29 cases). Other studies showed common problems of dislocation and shoulder instability, but a lower incidence of cemented cavity loosening of the humerus.
The allograft bone-prosthesis composite joint offers the best solution in this area by combining the advantages of both. Shoulder fusion should be the preferred method for patients who desire abduction, or for patients who have had their rotator cuff and deltoid removed. Allograft bone grafts, autogenous fibula grafts, or a combination of allograft bone and fibula grafts with a vascularized tip are used for fusion of the joint. A recent study comparing the function of the affected hand and forearm with that of the contralateral (healthy) side after these reconstructive methods found an acceptable level of patient satisfaction with regard to the maintenance of a high level of distal limb function, especially grip and forearm rotation.
The distal end of the femur and the proximal end of the tibia have considerable experience in the resection of periprosthetic tumors. Extensive resection of the tumor and reconstruction of knee dynamics with partial preservation of quadriceps function is often achieved. Arthrofusion is less commonly performed. The periprosthetic structures must be carefully evaluated to determine if the tumor has invaded the knee through the joint capsule or has caused a fracture. If in doubt, the joint should be understood through a small arthrotomy at the beginning of the procedure and an extra-articular resection should be performed promptly once the involvement of the joint has been determined.
In most cases, reconstructive methods include allograft, metal prosthesis or composite joint. The advantage of allograft bone grafting is that the surface of the adjacent joint can be preserved, and in children the epiphyseal plate can be preserved, but the rate of postoperative complications is higher with allograft bone. A recent long-term follow-up of 870 patients reported a 10% infection rate and a 19% fracture rate after allograft surgery. 16% of allografts eventually required total knee arthroplasty with a mean interval of 6 years, but long-term functional follow-up (Mankin score) was successful in 75% of patients. In children and adolescents, allograft bone grafts can overcome the disadvantages of metal prostheses, including the need to remove the uninvolved epiphyseal plate and the longevity of the metal prosthesis. A long-term study of 104 knee allografts showed a 5-year allograft lifespan of 73% and a 93% limb preservation success rate. Femoral allografts had better outcomes than tibial grafts, with 5-year life spans of 76% and 67%, respectively. In 86 of these patients who survived 2 years or more, the most significant complications were infection in 15% and fracture in 2%. Chemotherapy was responsible for affecting the healing of the grafted bone and the host, and in another study it was noted that 49% of patients with osteosarcoma treated with adjuvant chemotherapy experienced non-healing of the allograft bone.
Many complications limit the use of metal prostheses. In adults, metal prostheses are the commonly used method of reconstruction, but as the survival of patients with osteosarcoma increases, the longevity of prostheses for pediatric and adolescent patients must be considered. Designs now apply standard prostheses to improve the functionality of the artificial joint, so that custom-made prostheses are used less frequently. Although new designs that allow for a tighter fit of the stem can increase the reliability of the prosthesis, the main potential problem remains loosening of the prosthesis and mechanical damage. The hydroxyapatite coating on the surface of the prosthesis is effective in avoiding loosening. In a study of 68 cases of reconstructed prostheses with matched or custom-made prostheses, a 5-year survival rate of 83% and a 10-year survival rate of 67% were reported. 12 prostheses were revised, 11 of which were successful. The highest revision rate was seen in tumors of the proximal tibia (6/13), while the revision rate of the distal femur was only 10% (3/31). 11 patients (13%) developed infection and 6 of them required amputation. Postoperative functional scores (MSTS) were also lowest in patients with tumors of the proximal tibia. A major disadvantage of prosthetic application in this area is the inability to effectively anchor the hamate tendon to the prosthesis.
Surgical reconstruction in growing children Since the majority of osteosarcomas occur around the knee joint in children and adolescents, growth and limb function are major issues for them in the future. In patients treated with allogeneic bone grafts, limb isometry depends on the time of epiphyseal healing or lengthening of the limb. If the tumor is located in the diaphysis or epiphysis, it is possible that the epiphysis is not involved. This requires careful analysis of high-quality MRI, but preserving the epiphysis can preserve the articular surface and growth plate if possible. The growth of the preserved epiphysis may not be normal, but a recent study in children has shown that shortening of the limb after transepiphyseal resection for proximal tibial tumors is less than 3.5 cm and often achieves normal function. These authors used fibula with a vascularized tip combined with allograft bone for reconstruction.
An alternative approach is to apply a lengthenable prosthesis. There are many methods of prosthetic lengthening, and experience with this method is limited, but some follow-up has demonstrated that isometric lower limb length can be achieved after periprosthetic tumor resection. The choice of prosthesis depends on the surgeon. One approach is to use a standard prosthesis and periodically adjust the length of the body part of the prosthesis. This requires multiple surgeries and eventual replacement of the adult prosthesis after the child has fully developed. Lengthening of the prosthesis is often difficult because of the need to remove the fibrous scar tissue that encases the prosthesis. New designs are now more commonly used to allow lengthening of the prosthesis without surgery.
Rotational plication This procedure is appropriate for patients with large tumors of the distal femur in juveniles, but is sometimes indicated for adolescent patients with large tumors, intraosseous jumping metastases or pathologic fractures, or for patients who wish to continue sports activities after surgery. Its postoperative function is identical to that of a below-knee amputation, except for its profile, which is easily accepted by the patient selected. It makes sense for patients and their families to talk to a patient who has undergone rotational kyphoplasty or at least watch relevant video material and talk to an experienced rehabilitator. In a recent non-randomized study of 136 patients with metastasis-free osteosarcoma, the incidence of surgical complications was lower and the postoperative functional outcome (MSTS) was better than those of other limb-sparing procedures. Patients who underwent amputation also had a low complication rate, but those who underwent rotational plication had better postoperative function than those who underwent amputation or various other limb-preserving procedures. Although surgeons and patients often prefer other methods of limb preservation, rotational plication is still a very useful option.
Metastatic Osteosarcoma
Limb-sparing surgery in patients with only pulmonary metastases can achieve a survival rate of approximately 40%. Collaborative groups continue to improve treatment options for metastatic osteosarcoma. New chemotherapeutic agents are being used in phase II clinical trials. The purpose of these trials is to evaluate the response rate to tumors with drugs such as etoposide (VP16) and high-dose isocyclophosphamide and granulocyte colony-stimulating factor, all of which can be used in the treatment of metastatic osteosarcoma. These patients may also undergo resection of pulmonary metastases with adjuvant chemotherapy, and all tumor lesions in the bone and lung should be surgically removed. If these conditions are met and the patient is sensitive to chemotherapy, there is a 30-50% chance that the patient will achieve long-term survival, depending on the extent of tumor invasion. Patients with only pulmonary metastases have a better prognosis than those with bone metastases.