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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.