Ewing's sarcoma presenting as a solitary cyst

This case describes a 10-year-old girl who developed a Ewing's sarcoma in her proximal fibula. The radiologic features mimicked those of a unicameral bone cyst. The presence of pain and the atypical location led to a prompt biopsy and the correct diagnosis. The mechanism of this unusual radiographic presentation is discussed.

Intracortical chondroma: a report of two cases

Intracortical chondromas are exceedingly rare lesions that have the histopathologic appearance of enchondromas, but are located within cortical bone. Two new cases of intracortical chondroma, one symptomatic and the other found incidentally, are presented and the entity's brief literature reviewed.

Treatment of aneurysmal bone cysts of the pelvis and sacrum

BACKGROUND

Aneurysmal bone cysts are benign, non-neoplastic, highly vascular bone lesions. The purpose of this study was to describe the prevalence, the clinical presentation, and the recurrence rate of aneurysmal bone cysts of the pelvis and sacrum and to examine the diagnostic and therapeutic options and prognosis for patients with this condition.

METHODS

Forty consecutive patients with an aneurysmal bone cyst of the pelvis and/or sacrum were treated from 1921 to 1996. Their medical records and radiographic and imaging studies were reviewed, and histological sections from the cysts were examined. Seventeen lesions were iliosacral, sixteen were acetabular, and seven were ischiopubic. Seven involved the hip joint, and two involved the sacroiliac joint. All twelve sacral lesions extended to more than one sacral segment and were associated with neurological signs and symptoms. Destructive acetabular lesions were associated with pathological fracture in five patients and with medial migration of the femoral head, hip subluxation, and hip dislocation in one patient each. The mean duration of follow-up was thirteen years (range, three to fifty-three years).

RESULTS

Thirty-five patients who were initially treated for a primary lesion had surgical treatment (twenty-one had excision-curettage and fourteen had intralesional excision); two patients also had adjuvant radiation therapy. Of the thirty-five patients, five (14%) had a local recurrence noted less than eighteen months after the operation. Of five patients initially treated for a recurrent lesion, one had a local recurrence. At the latest follow-up examination, all forty patients were disease-free and twenty-eight (70%) were asymptomatic. There were two deep infections.

CONCLUSION

Aneurysmal bone cysts of the pelvis and sacrum are usually aggressive lesions associated with substantial bone destruction, pathological fractures, and local recurrence. Current management recommendations include preoperative selective arterial embolization, excision-curettage, and bone-grafting.

Pigmented villonodular synovitis: keys to early diagnosis

Pigmented villonodular synovitis is a synovial proliferative disorder that remains a diagnostic difficulty. Many clues in the history, physical examination, and radiographic studies can aid in the diagnosis. A patient in the third or fourth decade of life often will present with vague monoarticular complaints. Symptoms include intermittent, extreme deep pain localized to the hip, occasionally relieved by position. Decreased active and passive range of motion may be found. Small erosions in the head of the femur and acetabulum may occur early in the course of the disease. Magnetic resonance imaging is the imaging modality of choice and will show the characteristic findings of a joint effusion, synovial proliferation, and bulging of the hip. The synovial lining has a low signal on T1- and T2-weighted images, secondary to hemosiderin deposition. Pigmented villonodular synovitis should be included in the differential diagnosis of young patients with unexplained hip pain.

Method to remove intramedullary cement prior to mechanical testing in canine segmental replacement model

Mechanical evaluation of fixator augmented bone healing is complicated. When the primary interest is focused on mechanical properties of the healing site, implants may need to be removed before the testing. Cement or bone ingrowth related fixation requires special techniques for successful implant removal. Five canine femurs and five specially designed intramedullary cement fixated segmental replacement prosthesis were used to show that intramedullary cement mantle could be removed safely and the procedure was repeatable without altering the mechanical properties of healing site.

Mutation screening of the TNFRSF11A gene encoding receptor activator of NF kappa B (RANK) in familial and sporadic Paget's disease of bone and osteosarcoma

Paget's disease of bone (PDB) is a common disorder characterized by focal areas of increased and disorganized osteoclastic bone resorption, leading to bone pain, deformity, pathological fracture, and an increased risk of osteosarcoma. Genetic factors play an important role in the pathogenesis of Paget's disease. In some families, the disease has been found to be linked to a susceptibility locus on chromosome 18q21-22, which also contains the gene responsible for familial expansile osteolysis (FEO)--a rare bone dysplasia with many similarities to Paget's disease. Insertion mutations of the TNFRSF11A gene encoding Receptor Activator of NF kappa B (RANK) have recently been found to be responsible for FEO and rare cases of early onset familial Paget's disease. Loss of heterozygosity (LOH) affecting the PDB/FEO critical region has also been described in osteosarcomas suggesting that TNFRSF11A might also be involved in the development of osteosarcoma. In order to investigate the possible role of TNFRSF11A in the pathogenesis of Paget's disease and osteosarcoma, we conducted mutation screening of the TNFRSF11A gene in patients with familial and sporadic Paget's disease as well as DNA extracted from Pagetic bone lesions, an osteosarcoma arising in Pagetic bone and six osteosarcoma cell lines. No specific abnormalities of the TNFRSF11A gene were identified in a Pagetic osteosarcoma, the osteosarcoma cell lines, DNA extracted from Pagetic bone lesions, or DNA extracted from peripheral blood in patients with familial or sporadic Paget's disease including several individuals with early onset Paget's disease. These data indicate that TNFRSF11A mutations contribute neither to the vast majority of cases of sporadic or familial PDB, nor to the development of osteosarcoma.

The open section effect in a long bone with a longitudinal defect - a theoretical modeling study

A longitudinal defect dramatically alters the stress distribution within a long bone. The altered stress distribution can influence the structural properties of the bone and the stimulus for repair and remodeling of the defect and the surrounding bone. For applied torsion, the defect interrupts the normal shear flow around the bone. Reversal of the shear flow along the inner cortex of the bone is the primary characteristic of the "open-section" effect. Stress concentration effects also produce large stresses at the defect corners. A finite element model of a femur mid-diaphysis with a rectangular defect in the posterior cortex was developed to quantify the femur stress distribution and torsional stiffness for defect widths ranging from one-tenth of the femur outer diameter (0.1 OD) to 0.3 OD, and defect lengths ranging from 0.5 to 5 OD. Defects with a length of 1 OD or shorter had little influence on the femur torsional stiffness or the femur shear-stress distribution. The torsional stiffness decreased most dramatically as the defect length increased from 2 to 3 OD, but began to approach an asymptote near 5 OD. Shear flow reversal peaked at the center of the defect for defects longer than 1 OD, and the magnitude of the reversal began to approach an asymptote near 5 OD. For each defect, the largest stresses within the bone, developed at the defect corners. The results indicate that the open-section effect decreases the torsional stiffness and stress concentration effects decrease the torsional strength of a long bone with a longitudinal defect.

The role of MR imaging in soft tissue tumor evaluation: perspective of the orthopedic oncologist and musculoskeletal pathologist

Soft tissue masses are common in both children and adults. Clinicians must evaluate patients carefully to avoid management errors. The most effective management decisions are made when a working group composed of clinicians, radiologists, and pathologists participates in the interpretation of the imaging studies. Plain-film radiographs and MR imaging scans are the two main imaging modalities used in patients with soft tissue masses. The working group assimilates the clinical and radiographic data to determine if they can identify the nature of the soft tissue mass. When the group can assign a definitive diagnosis, the lesion is designated as a determinate lesion. Determinate lesions include lipomas, ganglions, hemangiomas, neurofibromas, diabetic myonecrosis, muscle tears, myositis ossificans (heterotopic ossification), and pigmented villonodular synovitis. When the process cannot be identified, the lesion is classified as indeterminate. All soft tissue sarcomas are indeterminate lesions. Many benign lesions are also indeterminate. Common examples include schwannomas, myxomas, and giant cell tumor of tendon sheath. Based on the clinical and radiologic features, these diagnoses may be suspected, but because of the inability to distinguish them from sarcomas based on the MR imaging features, they are usually classified as indeterminate. When lesions are judged to be determinate, observation or excisional biopsy are the two major treatment choices. When lesions cannot be identified on the imaging studies, incisional or needle biopsy is performed to establish a diagnosis. Once a diagnosis is made, the proper management choice can be selected. Inappropriate excisional biopsy is the major treatment error in the management of soft tissue tumors. When a high-grade soft tissue sarcoma is resected with multiple positive margins, the risk of local failure after definitive resection is much higher than if the patient had been treated initially with only a needle or incisional biopsy. Also, if a major complication, such as an infection, a major wound-healing problem, or contamination of the major neurovascular structures, occurs at the time of incisional biopsy, amputation of the limb may be necessary. Inappropriate excisional biopsy can occur when a surgeon is not familiar with the features of sarcomas or when a radiologist mistakenly interprets the signal features as a benign lesion.

Clinicopathologic features and treatment of postirradiation sarcoma of bone and soft tissue

BACKGROUND AND OBJECTIVES

An analysis of the clinicopathologic features and treatment of patients with postirradiation sarcoma of bone and soft tissue was performed to guide modern evaluation and management.

METHODS

A retrospective analysis of 135 sarcomas in 130 patients was performed.

RESULTS

The mean age of the 130 patients was 48 years, and there was a female predominance because of irradiation for carcinomas of the breast and uterus. Indication for irradiation was a soft tissue lesion (such as lymphoma or breast cancer) in 58.5% of patients and a bone lesion (such as giant cell tumor or fibrous dysplasia) in 41.5%. The latent period (interval between irradiation and discovery of the sarcoma) ranged from 4-55 years (mean, 17 years). Of the lesions, 74% were stage IIB (high-grade extra-compartmental) and 24% were stage III (metastases). Ninety-four patients received their treatment at our institution. Of the 61 patients with resectable disease, 49 had amputations and 12 had limb salvage procedures. The 5-year cumulative survival rate was 68.2% for patients with peripheral (extremities, including proximal femur and hip) resectable lesions and 27.3% for patients with central (pelvis, head/neck, and ribs) resectable lesions. The local recurrence rate correlated with the surgical margin achieved: intralesional, 73%, marginal, 64%, and wide, 23%.

CONCLUSIONS

The prognosis for patients with peripheral resectable postirradiation sarcomas is good if a wide surgical margin can be achieved. This group of patients should be treated aggressively because they have a new cancer.

Soft-tissue masses: when and how to biopsy

Patients with soft-tissue tumors present a diagnostic challenge to the clinician. A systematic approach to evaluation and biopsy is necessary to minimize diagnostic errors and biopsy complications. With MRI, the clinician and radiologist are able to precisely identify some soft-tissue masses, such as lipomas, ganglions, hemangiomas, and popliteal cysts. Most soft-tissue tumors have signal characteristics that are low signal on T1-weighted images and high signal on T2-weighted images. Soft-tissue masses that cannot be identified are called indeterminate masses, and a biopsy is necessary to identify these lesions. Needle biopsy and open incisional biopsy are effective methods to histologically identify the nature of the tumor. Open excisional biopsy should be performed only when the surgeon knows that the soft-tissue lesion is benign.

Stress and micromotion in the taper lock joint of a modular segmental bone replacement prosthesis

The stress distribution within the components and the micromotion of the interface significantly influence the long-term function of the taper lock joint in a modular segmental bone replacement prosthesis. Bending-induced gap opening between the cone and the sleeve can lead to an inflow of biological fluids, and thus accelerate implant corrosion. Local areas of high stress can also accelerate the corrosive processes and initiate local yielding, which may lead to a fracture in one of the components. In this study, a 3-D finite element (FE) model of a modular segmental bone replacement prosthesis was developed to study the interface micromotion and component stress distribution under the maximum loads applied during gait for a taper lock joint with multiple material combinations. Bending was the main cause of the local high stresses and interface separation within the taper joint. For Ti6A14V components, cortical bone bridging and ingrowth across the taper lock gap reduced the peak stress by 45% and reduced the contact interface separation by 55%. Such tissue formation around the taper lock joint could also form a closed capsule to restrict the migration of potential wear particles and thus prevent the biologic process of bone resorption induced by metal debris.

Clinicopathologic features and treatment of postirradiation sarcoma of bone and soft tissue

BACKGROUND AND OBJECTIVES

An analysis of the clinicopathologic features and treatment of patients with postirradiation sarcoma of bone and soft tissue was performed to guide modern evaluation and management.

METHODS

A retrospective analysis of 135 sarcomas in 130 patients was performed.

RESULTS

The mean age of the 130 patients was 48 years, and there was a female predominance because of irradiation for carcinomas of the breast and uterus. Indication for irradiation was a soft tissue lesion (such as lymphoma or breast cancer) in 58.5% of patients and a bone lesion (such as giant cell tumor or fibrous dysplasia) in 41.5%. The latent period (interval between irradiation and discovery of the sarcoma) ranged from 4-55 years (mean, 17 years). Of the lesions, 74% were stage IIB (high-grade extra-compartmental) and 24% were stage III (metastases). Ninety-four patients received their treatment at our institution. Of the 61 patients with resectable disease, 49 had amputations and 12 had limb salvage procedures. The 5-year cumulative survival rate was 68.2% for patients with peripheral (extremities, including proximal femur and hip) resectable lesions and 27.3% for patients with central (pelvis, head/neck, and ribs) resectable lesions. The local recurrence rate correlated with the surgical margin achieved: intralesional, 73%, marginal, 64%, and wide, 23%.

CONCLUSIONS

The prognosis for patients with peripheral resectable postirradiation sarcomas is good if a wide surgical margin can be achieved. This group of patients should be treated aggressively because they have a new cancer.

Primary fibrosarcoma of bone. Outcome after primary surgical treatment

To investigate outcome and evaluate prognostic factors in primary fibrosarcoma of bone, all patients at the authors' institution who had surgical treatment for primary fibrosarcoma of bone from 1910 to 1995 were studied. Medical records, surgical reports, radiographs, and histologic slides of 92 patients (51 males, 41 females; mean age, 38 years; range, 8-84 years) were reviewed. The most common tumor locations were the femur (28 patients), tibia (21 patients), and pelvis (14 patients). Sixty-one tumors (66%) were Enneking Stage IIB. Twenty-nine patients (31.5%) had adjuvant therapy: 16 had radiation, nine had chemotherapy alone, and four had radiation and chemotherapy. Amputation or disarticulation was performed in 61 patients (66%), wide excision was performed in 13 (14%), marginal excision was performed in 15 (16%), and intralesional excision was performed in three (3.3%). Local recurrence occurred in 14 patients (15%) at a median time of 7 months (range, 3-21 months). Metastases developed in 58 of the 85 patients (68%) with Stage I or II tumors at presentation, at a median of 9 months (range, 1-51 months). Survivorship analysis showed that the overall probability of survival was 33.4% at 5 years after surgery. Multivariate analysis showed that the main prognostic risk factors affecting overall survival included age older than 40 years, tumor location in the axial skeleton, and high-grade tumor (Grade 3 or 4). With the high incidence of systemic failure after surgical treatment, perioperative adjuvant treatment modalities should be considered.

Pigmented villonodular synovitis of the hip and knee

Pigmented villonodular synovitis is an uncommon disease that remains a diagnostic challenge. Presenting complaints commonly involve one joint, most often the knee or hip. Symptoms of pain and swelling characteristically have an insidious onset and are slowly progressive. The physical examination may be completely normal. Radiographs of the knee may appear normal or may show a periarticular soft tissue density, expansion of the suprapatellar pouch and local osseous changes confined to the patellofemoral articulation. Radiographs of the hip may show erosions in the head and neck of the femur and acetabulum. Magnetic resonance imaging usually demonstrates key diagnostic features, which include joint effusion, elevation of the joint capsule, hyperplastic synovium and low signal intensity resulting from hemosiderin deposition. The diagnosis of pigmented villonodular synovitis is confirmed by biopsy, and the treatment of choice is synovectomy.

Osteosarcoma of the head and neck: a review of the Johns Hopkins experience

OBJECTIVE

To determine factors including treatment modalities which influence survival in patients with osteosarcoma of the head and neck.

STUDY DESIGN

Retrospective clinicopathologic study of 27 patients with osteosarcoma of the head and neck.

METHODS

The clinical charts and pathology slides were reviewed on 27 patients who had osteosarcoma of the head and neck between 1946 and 1998. The following variables were examined for their effect on survival: age of diagnosis, site of tumor, presentation, race, sex, prior radiation exposure, retinoblastoma history, margin status, and method of treatment.

RESULTS

The average age at the time of diagnosis of the patients was 37.6 years (range, 7-82 y). The sex distribution was similar with 14 male and 13 female patients. Eight of 27 patients had osteosarcoma of the mandible, 9 of 27 had osteosarcoma of the maxilla and paranasal sinuses, and in 10 of 27 patients osteosarcoma occurred elsewhere, including the temporal bones, occipital bones, and orbit. The overall 2-year survival was 66% with a 5-year survival rate of 55%.

CONCLUSIONS

Positive surgical margins and a high tumor grade were found to have a statistically deleterious effect on overall survival. There was no detectable effect on survival of age, race, sex, prior radiation exposure, tumor site, and tumor cell type. It was not possible to differentiate between the different adjuvant treatment modalities because of the small numbers in the study.

Endovascular papillary angioendothelioma (Dabska tumor) of bone

Endovascular papillary angioendothelioma, also known as Dabska tumor, is a rare vascular neoplasm that usually involves the skin or subcutaneous tissue of children. There have been no reported cases of this lesion occurring in bone. We report a Dabska tumor in the distal femur of a 45-year-old woman who, clinically and radiologically, was felt to have an osteoid osteoma. Histologic study of the lesion showed a hemangioma with budding fronds of endothelial cells, a feature characteristic of the Dabska tumor. We feel that the lesion arose in a pre-existing hemangioma, a hypothesis suggested in a few other case reports. Endovascular papillary angioendothelioma is a low-grade malignant neoplasm, although only one patient has died due to this lesion. Our patient is asymptomatic without evidence of recurrence 1 year post curettage.

Effect of intramedullary polymethylmethacrylate and autogenous cancellous bone on healing of frozen segmental allografts

This study was designed to compare bone mineral density, periosteal callus production, new bone formation, bone porosity, histologic appearance, and union of mid-diaphyseal segmental allografts of the femur stabilized with an interlocking nail technique in a canine model 6 months after the procedure. An in vivo study was performed to compare the effects of augmenting interlocking nail fixation with an interlocking nail alone, intramedullary polymethylmethacrylate, intramedullary polymethylmethacrylate and autogenous cancellous bone applied to the periosteal surface of the host-allograft junction, autogenous cancellous bone applied to the endosteal surface of the allograft, autogenous cancellous bone applied to the periosteal surface of the host-allograft junction, and autogenous cancellous bone applied to the periosteal surface of the host-allograft junction and to the endosteal surface of the allograft. There were no differences among treatments for bone mineral density at any time interval. Callus area 4 weeks after the procedure was greater along the lateral and cranial surfaces for treatments with periosteal cancellous bone (p < 0.05). New bone within the allograft segment did not differ among treatments and was reduced compared with the host-allograft junctions (p < 0.05). The amount and quality of bone tissue at the host-allograft junctions were greatest with treatments of intramedullary polymethylmethacrylate and autogenous cancellous bone applied to the periosteal surface of the host-allograft junction and of autogenous cancellous bone applied to the periosteal surface of the host-allograft junction and to the endosteal surface of the allograft (p < 0.05). The rate of bone union was lower, and there was a greater gap (non-bone tissue) remaining between host and allograft bone with treatment involving just intramedullary polymethylmethacrylate than with other treatments (p < 0.05). The results suggest that augmenting interlocking nail fixation with intramedullary polymethylmethacrylate by itself offers no advantage but that a combination of intramedullary polymethylmethacrylate and cancellous bone at the periosteal surface or of cancellous bone within the medullary canal and at the periosteal surface improves the quality of healing at 6 months.

In vitro and in vivo study on the effect of autogenous cancellous bone and intramedullary polymethylmethacrylate on allograft construct strength

An in vitro study was performed to compare the effects of augmenting interlocking nails of one of two diameters (5 or 6 mm) with intramedullary polymethylmethacrylate. Subsequently, an in vivo study was performed to compare the effects of augmenting the interlocking nail with five combinations of intramedullary polymethylmethacrylate and autogenous cancellous bone applied to the periosteal surface or within the medullary canal. Dogs were killed 6 months after the procedure for biomechanical evaluation of the femora in axial compression, mediolateral and craniocaudal bending, and torsion. Results from the in vitro study at the proximal osteotomy indicated the 6-mm interlocking nail with intramedullary polymethylmethacrylate had greater stiffness than the 5-mm interlocking nail without it (p < 0.05). At the distal osteotomy, regardless of the diameter of the interlocking nail, the addition of intramedullary polymethylmethacrylate increased stiffness (p < 0.05). Results from the in vivo study indicated greater global construct stiffness with an interlocking nail alone, an interlocking nail augmented with intramedullary polymethylmethacrylate and cancellous bone at the periosteal surface, and an interlocking nail augmented with cancellous bone within the medullary canal and at the periosteal surface (p < 0.05). At the osteotomy level, the interlocking nail augmented with intramedullary polymethylmethacrylate and cancellous bone at the periosteal surface had greater stiffness than did an interlocking nail alone or an interlocking nail augmented with either intramedullary polymethylmethacrylate, cancellous bone within the medullary canal, or cancellous bone at the periosteal surface (p < 0.05) but produced the same results as an interlocking nail augmented with cancellous bone within the medullary canal and at the periosteal surface. The results suggest that augmenting interlocking nail fixation with intramedullary polymethylmethacrylate by itself offers no advantage but that a combination of intramedullary polymethylmethacrylate and cancellous bone at the periosteal surface improves structural properties at 6 months.

CT and MRI evaluation of musculoskeletal infection

While the plain film and nuclear medicine bone scan are still the traditional imaging modalities used in the evaluation of musculoskeletal infection, the cross-sectional imaging modalities, computed tomography (CT) and magnetic resonance imaging (MRI), have become critical in the delineation of many types of musculoskeletal infection. In particular, the evaluation of soft tissue infections, including cellulitus, myositis, fasciitis, abscess, and septic arthritis are often best evaluated by MRI or CT due to their excellent anatomic resolution and soft tissue contrast. Even in osseous infection, CT and MRI can give better anatomic delineation of the extent of infection. In cases where the plain film and nuclear medicine bone scan findings are complicated due to previous surgery, trauma, or underlying illness, the anatomic resolution and soft tissue contrast provided by MRI and CT are often necessary to determine if underlying infection exists. MRI's visualization of the bone marrow allows for the sensitive detection of osteomyelitis, although specificity for the diagnosis of osteomyelitis is aided by other findings, including cortical destruction. The CT and MRI findings in the spectrum of musculoskeletal infections are discussed and contrasted, and pitfalls in their evaluation of musculoskeletal infection are described.

The short-term effects of cisplatin chemotherapy on bone turnover

Cisplatin is an effective agent in the treatment of osteosarcoma of bone but little is known of its effects on normal bone turnover. Twenty-four dogs divided into three study groups were used to study the effect of cisplatin on normal bone turnover at the distant site of surgery. Group 1 served as the control group, group 2 received four cycles of cisplatin every 3 weeks before the surgery, and group 3 received four cycles postoperatively. The bone turnover rate was evaluated by measuring levels of systemic bone markers, osteocalcin, alkaline phospohatase, urine pyridinoline cross-links, and by determination histomorphometric indices. Histomorphological analysis showed poor correlation on bone formation with systemic bone markers at distant sites of surgery. Histomorphometrically normal bone turnover was affected by administration of cisplatin, but the effect was temporary, late, and less significant than what occurred at the surgical site. Our data showed that significant effects of cisplatin are observed at the site of active cellular induction and proliferation, such as implant-host interface, and less effects are seen at the sites of normal bone turnover.

Skeletal system: biomechanical concepts and relationships to normal and abnormal conditions

The human skeleton is a remarkable organ that is uniquely designed to provide structural support and to house the body's hematopoietic system and mineral reservoirs. Seven concepts that will assist the clinician in understanding skeletal function are (1) material properties of bone, (2) stress and strain, (3) bending moments and torsional loads, (4) area moments of inertia, (5) fatigue and catastrophic failure, (6) Wolff's law, and (7) stress risers and open section effect. For example, as the modulus of a bone, a measure of stiffness decreases as in Padget's disease or fibrous dysplasia and the same levels of stress will cause greater deformations. The sum of these principles also explains the torus fracture (ductility), fracture of the olecranon by contracting tricep muscle (tensile loading), osteoporotic compression fracture of the spine, and the other biomechanical lesions that are encountered. Understanding these basic biomechanical principles can help physicians comprehend neoplastic processes and fractures that are the metabolic responses of the skeleton to stress and that appear on the radionuclide bone scan.

Effect of cisplatin chemotherapy on extracortical tissue formation in canine diaphyseal segmental replacement

The reconstruction of large bone and joint defects after the resection of malignant tumors remains a major challenge. Chemotherapy has significantly lowered the risk of metastasic disease, but complications associated with reconstructive techniques continue to result in late morbidity. In the present study, biomechanical torsion testing, gait analysis, and histomorphometric and scanning electron microscopic evaluations of 24 dogs were used to examine the effects of preoperative and postoperative administration of cisplatin on the biologic fixation of a porous-coated segmental replacement prosthesis. The chemotherapy consisted of four cycles of cisplatin administered at a dosage of 75 mg/m2 preoperatively or postoperatively. The healing was enhanced by use of an autogenous corticocancellous bone graft. The graft was placed evenly around the prosthesis and the adjacent femoral cortex. Mechanical analyses of torsional stiffness, yield strength, and maximum strength revealed no statistically significant differences between the groups at 12 weeks. Such lack of difference was mainly due to the penetration of highly organized fibrous tissue into the porous surface; this provided strong fixation of the implant to bone even in the absence of bone ingrowth. Although bone ingrowth into the prostheses was not affected, electron microscopic, histomorphometric, and radiologic analyses showed a clear difference in the formation of new bone around the prosthesis. Preoperative chemotherapy did not alter the formation of new bone, but specimens from animals treated postoperatively with cisplatin showed significantly less bone graft resorption and less new bone formation. Hence, the effect of cisplatin administration caused only a temporary delay, not a permanent effect, on extracortical capsule formation. The formation of extracortical bone and soft tissue might prevent debris-incised osteolysis and, therefore, prevent late complications by forming a tight capsule around the bone-prosthetic interface.

Benign and malignant musculoskeletal masses: MR imaging differentiation with rim-to-center differential enhancement ratios

PURPOSE

To assess the diagnostic potential of the rim-to-center differential enhancement ratio in the magnetic resonance (MR) imaging differentiation of benign from malignant musculoskeletal masses.

MATERIALS AND METHODS

Dynamic gadolinium-enhanced fast multiplanar spoiled gradient-recalled acquisition in the steady state imaging was performed to evaluate 17 one and soft-tissue masses (10 malignant, seven benign) in 14 patients. The rim-to-center differential enhancement ratio was determined from images at the maximal enhancement rate. The difference in differential enhancement ratios between benign and malignant masses was evaluated and compared with the maximum rate of enhancement for each mass.

RESULTS

Nine of 10 malignant masses showed rapid rim enhancement with delayed central fill-in. This enhancement pattern was absent in benign masses. The average rim-to-center differential enhancement ratio was 0.64 +/- 0.26 for malignant masses and -0.16 +/- 0.33 for benign masses (P < .001). This difference was statistically significant. The average maximum rate of enhancement was 3.41%/sec +/- 2.20 for malignant masses and 2.74%/sec +/- 2.46 for benign masses (P > .05).

CONCLUSION

Intratumoral enhancement patterns of malignant and benign masses differ because of differences in vascular architecture. These preliminary results suggest that the rim-to-center differential enhancement ratio has potential as an additional parameter for the MR imaging differentiation of indeterminate musculoskeletal masses.

Special problems in limb-salvage surgery

Limb-salvage surgery is a safe and effective treatment for malignancies of the musculoskeletal system. Careful evaluation and planning are necessary to avoid both early and late complications. Biopsy must be carefully performed to avoid unnecessary contamination and to obtain adequate tissue for an accurate diagnosis. Pathologic fractures present both a diagnostic and a therapeutic challenge, and evaluation strategies depend on the age of the patient. Treatment of a pathologic fracture depends on the location and the histology of the lesion and many host factors. Limb salvage may or may not be indicated. Instability is another problem with certain limb-salvage situations, e.g., when it is necessary to resect the scapula. Various approaches may obviate the problem. The salvage of failed limb-salvage procedures requires careful evaluation and planning. Patients with infections and local recurrences often require amputation surgery. Correctable problems following failed allograft reconstructions include collapse of the articular cartilage, joint instability, nonunion, and fracture of the allograft. Correctable problems following prosthetic arthroplasty include aseptic loosening, prosthetic fracture, and polyethylene wear. Approximately two thirds of patients with failed limb-salvage procedures will obtain a functional limb following revision surgery. Attention to these special problems may allow for greater success with limb-salvage surgery.

Development of a canine chemotherapeutic model with ifosfamide

The purpose of this study was to develop a canine experimental model for neoadjuvant chemotherapy of primary bone tumors with ifosfamide, which is safe and clinically relevant for use in human beings with bone tumors. Our study was divided into two steps, each with four dogs. In the first step ifosfamide was administered for 4 consecutive days in three cycles with 3-week intervals between each cycle. For this first step a daily dosage of 300 mg/m2 of body surface resulted in only moderate leukopenia, whereas a daily dosage of 450 mg/m2 caused severe leukopenia. Therefore, to determine the maximal dose tolerable and to verify the results from step 1, we administered the higher daily dosage of 450 mg/m2 in step 2 for four successive cycles with 3-week intervals. In each step one dog died acutely after the first cycle of chemotherapy. In addition during step 2 one dog died of overwhelming sepsis after the second cycle of ifosfamide. The remaining five dogs survived without other appreciable laboratory abnormalities. Neither hematuria nor proteinuria was observed throughout the course of study, and relevant findings were not observed at autopsy. We determined that 450 mg/m2 was the maximal tolerated dosage of ifosfamide for our regimen, with the dose-limiting factor being myelosuppression, specifically leukopenia. Using this canine model, we can estimate the effect of ifosfamide on bone graft incorporations and the fixation of biologic prostheses that is clinically the most important aspect of limb salvage surgery.

Clinicopathologic features and treatment of osteoid osteoma and osteoblastoma in children and adolescents

Benign bone-forming tumors are common in children. Careful radiographic imaging is necessary to plan surgical treatment. Careful histologic study is necessary to distinguish osteoblastoma from more aggressive tumors. Osteoid osteoma should be considered when the child or adolescent presents with pain in an extremity or along the spine.

Survival after pulmonary metastasectomy in soft tissue sarcoma. Prognostic factors in 214 patients

This retrospective study examines prognostic factors for post-metastasectomy survival in soft tissue sarcoma patients. Between 1976 and 1992, 274 consecutive patients (median age 49 [7-96] years) with pulmonary metastatic soft tissue sarcoma of the extremity or trunk wall (31 at presentation) were managed at the Mayo Clinic. 214 underwent pulmonary metastasectomy and 163 of these also received adjuvant chemotherapy. There were 195 local excisions, 14 lobectomies, and 5 pneumonectomies. 90 patients had solitary metastases, 184 patients had 2 or more metastases. 31% of patients had MFH tumors and 88% of all tumors were high grade. Median follow-up for survivors was 8 (2-21) years. 5-year overall survival after metastasectomy was approximately 40% (cf. 20% for non-metastasectomy). Age > 50, MFH tumors, > or = 2 metastases, metastasis size > 2 cm, metastasis-free period < or = 18 months, and the use of adjuvant chemotherapy were univariately unfavorable factors. Size of metastasis > 2 cm, number of metastases > or = 2, and metastasis-free interval < or = 18 months were independently unfavorable for survival. In a prognostic system, patients with 0 risk factors had a 60% 5-year survival, those with 1, 2, or 3 of these factors had 30%, 20% and 0% survival, respectively.

Differentiation of benign and malignant musculoskeletal tumors: potential pitfalls with MR imaging

Magnetic resonance (MR) imaging is the most sensitive and accurate imaging technique for evaluation of musculoskeletal tumors. With increasing clinical experience, however, an overlap between the classic characteristics of benign and malignant tumors is frequently observed. In a prospective analysis of 87 consecutive cases of musculoskeletal tumors, the malignancy of skeletal lesions was correctly assessed with MR imaging in 55% of the cases. In 39% of the cases, the malignancy of skeletal lesions was overestimated with MR imaging. Correlation with plain radiography is extremely important in such cases and would have resulted in correct assessment of 73% of the skeletal lesions. For soft-tissue lesions, a large variability is found in the benign versus malignant appearances of lesions on MR images, with poor correlation between classic benign characteristics and the benignity of the lesion (17% of cases). The exceptions are hemangiomas and lipomas, which have characteristic appearances on MR images. Knowledge of potentially misleading appearances of musculoskeletal tumors on MR images allows more accurate diagnosis of such tumors.

Orthopaedic management using new devices and prostheses

The goals of treatment for patients with metastatic disease are control of pain and maintenance of function. Prosthetic arthroplasty is a useful technique for selected indications. Specific indications include (1) reconstruction of large destructive areas that are not amenable to internal fixation, (2) salvage of failed internal fixation devices, and (3) salvage of lesions in which there are no radiotherapy options to prevent disease progression. Custom modular devices allow resection of varying segments of the skeleton. Immediate rigid fixation is achieved with cemented intramedullary stems. Patients are allowed to bear full weight as tolerated immediately postoperatively. A custom modular diaphyseal segmental replacement system allows resection of large diaphyseal lesions and immediate fixation. The complication rate is low after arthroplasty.

Osteosarcoma of the diaphysis of long bones: clinicopathologic features and treatment of 51 cases

Of 1000 osteosarcoma cases recorded in the Mayo Clinic records, approximately 7% of the lesions occurred in the diaphysis of long bones, mostly in the femur, tibia, and humerus. The average age of the patients with these lesions was 28 years (range: 8 to 67). The duration of their symptoms before diagnosis was greater than that for patients with conventional osteosarcoma in the metaphysis. In approximately 20% of the cases, the radiographic appearance mimicked that of Ewing's sarcoma. Amputation surgery was the major form of treatment. The 2-, 5- and 15-year survival was 42%, 29%, and 20%, respectively.

Protected early motion versus cast immobilization in postoperative management of ankle fractures

Sixty-one active-duty military personnel with operatively treated ankle fractures were randomized into two postoperative immobilization regimens: Group I--six weeks short-leg cast, nonweight-bearing; Group II--six weeks removable orthosis, nonweightbearing. Group I began physical therapy at six weeks postoperatively, and Group II began physical therapy within the first postoperative week. Objective measurements of swelling, strength, range of motion, and functional tests were examined. Subjective scores of pain, function, cosmesis, and motion were recorded. Patients in Group II (early mobilization) had significantly better subjective scores at three and six months postoperatively; however, time to return to duty was not significantly different. Objective tests of swelling, strength, range of motion, and functional tests were not significantly different at three months postoperatively for either group. Early mobilization in a removable orthosis, while not objectively altering the postoperative course, provides a safe, preferable method of treatment in the reliable and cooperative patient.

Medial meniscal cyst of the knee simulating a solitary bone lesion. A case report and review of the literature

Meniscal cysts are common lesions, but extensive bony changes arising from these cysts are exceedingly rare. These changes are usually erosive defects about the tibia. Dull pain with an associated mass are classic findings. Magnetic resonance imaging is useful in making the diagnosis and arthroscopic management yields excellent results. A 47-year-old man developed a symptomatic medial meniscal cyst that invaded the medial femoral condyle simulating a solitary bone lesion. Magnetic resonance imaging revealed the contiguous nature of the cyst with the meniscus. Arthrotomy with cyst excision was required in this case and led to the amelioration of symptoms.

Parosteal osteosarcoma. A clinicopathological study

The records of 226 patients (sixty-seven who were managed at our institution and 159 who were identified from the consultation files) who had had a parosteal osteosarcoma were reviewed. The criteria for diagnosis were that, roentgenographically, the lesion had arisen from the surface of the bone and that, histologically, the tumor was well differentiated (Grade 1 or 2); it was characterized by well formed osteoid within a spindle-cell stroma; and, when there was medullary involvement, less than 25 per cent of the medullary cavity was affected. Dedifferentiation was more common (16 per cent of the patients) than previously reported and was associated with a poor prognosis. Cross-sectional imaging studies demonstrated medullary involvement in 22 per cent of the patients, an unmineralized soft-tissue mass peripheral to the mineral component in 51 per cent, and adjacent soft-tissue invasion in 46 per cent. In contrast to the findings in our previous studies, medullary involvement was not a poor prognostic factor. At an average of thirteen years (range, two to forty-one years), eleven of the sixty-seven patients who were managed at our institution died of the tumor; ten of these patients had a dedifferentiated tumor. Statistical analysis of the thirty-nine patients who had had the primary treatment at our institution revealed that incomplete resection was associated with an increased risk of local recurrence and that dedifferentiation markedly increased the risk of metastasis.

Treatment of giant-cell tumor of the pelvis

Nineteen patients who had a giant-cell tumor of the pelvis were managed from 1944 through 1989. Thirteen of the patients were in the third or fourth decade of life. The ileum was involved in thirteen patients; the pubis, in two; the ischium, in three; and the pubis and ischium, in one. Five patients who had an initial Stage-II (active) lesion were managed with curettage; in one of the five, a local recurrence developed at twelve months, and the other four had no evidence of disease from nine to forty-six years after the curettage. Eight patients who had a Stage-III (aggressive) lesion were managed with resection of most of the lesion followed by curettage of any remaining positive margins; four of the eight also received adjuvant irradiation. None of the eight had a local recurrence; six had no evidence of disease from eight to twenty-seven years after the operation, one died because of a metastatic post-radiation sarcoma thirteen years after the operation, and one was asymptomatic but had pulmonary metastases three years after the operation. Four patients who had a Stage-III recurrent local tumor when they were first seen were managed with hemipelvectomy, wide resection, resection and curettage, and curettage and arthroplasty (one procedure each). Three had no evidence of disease seven to twenty years after the operation and one had died because of a post-radiation metastatic osteosarcoma eight years after the operation. Two patients who had Stage-III disease were managed with external beam radiation alone. One had no evidence of disease twenty-six years later. The other had a recurrence one year later, which was treated with additional irradiation; a second recurrence was treated with curettage and bone-grafting. Twenty-eight years after the initial radiation treatment, this patient had no evidence of disease. External beam irradiation was used for a total of eight patients; a post-radiation sarcoma developed in two.

Ewing sarcoma of the pelvis. Clinicopathological features and treatment

The results of treatment in twenty-seven patients who had a Ewing sarcoma of the pelvis were reviewed. Six patients had had metastatic disease at the time of the diagnosis. The three-year actuarial survival of these patients was 17 per cent (95 per cent confidence interval, 8 to 52 per cent). Of the twenty-one remaining patients, thirteen had received chemotherapy and radiation therapy to the primary lesion and eight had had chemotherapy and operative resection, with or without radiation therapy. The actuarial five-year over-all survival was 25 per cent (95 per cent confidence interval, 6 to 51 per cent) in the group that had had radiation without a resection and 75 per cent (95 per cent confidence interval, 31 to 93 per cent) in the group that had had a resection (p < 0.005, log-rank method). The actuarial over-all five-year survival was 45 per cent (23 to 65 per cent) for all patients who had had localized disease when first seen. Actuarial local failure analysis (the censoring of patients who died without evidence of local failure before the two-year follow-up examination) revealed a rate of local failure of 44 per cent (14 to 79 per cent) in the group that had been treated with chemotherapy and radiation alone compared with 13 per cent (0 to 53 per cent) in the patients who had had a resection, but this difference was not significant (p > 0.25, log-rank method).(ABSTRACT TRUNCATED AT 250 WORDS)