Megavoltage radiotherapy for aneurysmal bone cysts.

PURPOSE: An aneurysmal bone cyst (ABC) is a rapidly expansile and destructive benign tumor of bone that is usually treated by curettage and bone graft, with or without adjuvant treatment. For recurrent tumors, or tumors for which surgery would result in significant functional morbidity, does radiotherapy (RT) provide a safe and effective alternative for local control? PATIENTS AND METHODS: Nine patients with histologically diagnosed aneurysmal bone cysts without other associated benign or malignant tumors were treated at the University of Florida with megavoltage RT between February 1964 and June 1992. The patients received local radiotherapy doses between 20 and 60 Gy, with 6 patients receiving 26--30 Gy. In 6 patients the diagnosis was made by biopsy alone; 3 underwent intralesional curettage before RT. Minimum follow-up was 20 months; 7 of 9 patients (77%) had follow-up greater than 11 years. RESULTS: No patient experienced a local recurrence (median follow-up, 17 years). One patient required stabilization of the cervical spine 10 months after RT because of dorsal kyphosis from vertebral body collapse. No other significant side effects were experienced, and no patients developed secondary malignancies. Four patients were lost to follow-up: at 20 months, 11.5 years, 17 years, and 20 years after the initiation of treatment, none with any evidence of local recurrence. All of the patients who had significant pain before RT had relief of their symptoms within 2 weeks of completion of therapy. CONCLUSIONS: Using modern-day RT, patients with recurrent or inoperable aneurysmal bone cysts can be treated effectively (with minimal toxicity) using a prescribed tumor dose of 26--30 Gy.

In vitro strength comparison of hydroxyapatite cement and polymethylmethacrylate in subchondral defects in caprine femora.

Hydroxyapatite cement was investigated in situ for the reconstruction of juxta-articular defects. Polymethylmethacrylate is currently the most commonly used material for the reconstruction of bone defects following the exteriorization and curettage of aggressive benign tumors. In vitro, we compared the effects of hydroxyapatite cement and polymethylmethacrylate in restoring the stiffness of the subchondral plate in a caprine femoral defect model. Ten matched pairs of caprine femora underwent nondestructive compression testing normal to the load-bearing surface. A standardized subchondral defect 12 mm in diameter was created in the medial femoral condyle. Compression testing was repeated to determine the reduction in stiffness caused by the defect. Each femur from each pair was randomly assigned to one of two groups (n=9), and the defects were augmented with either polymethylmethacrylate or hydroxyapatite cement. After 12 hours, compression testing was repeated to determine the subchondral stiffness after augmentation. Compared with intact femora, the defect specimens that were later treated with either polymethylmethacrylate or hydroxyapatite cement exhibited stiffness values of 70 (386+/-107 N/mm) and 59% (343+/-94 N/mm) respectively, which represented a significant reduction in stiffness (p=0.05). Augmentation with polymethylmethacrylate or hydroxyapatite cement restored stiffness by 81 (450+/-111 N/mm) and 71% (413+/-115 N/mm), respectively, of the values of intact specimens. Hydroxyapatite cement restored stiffness significantly (p=0.05) over the stiffness of the nonaugmented defect compared with the stiffness after augmentation with polymethylmethacrylate (p=0.12). Neither polymethylmethacrylate nor hydroxyapatite cement restored stiffness to that of intact femora (p=0.05). In the current detect model, hydroxyapatite cement was comparable with polymethylmethacrylate in restoring subchondral stiffness. Unlike polymethylmethacrylate, however, hydroxyapatite cement has the following advantages: it is osteoconductive, is replaced by host bone, and avoids the potential for thermal necrosis. Hydroxyapatite cement may therefore provide a viable alternative to polymethylmethacrylate for augmentation of juxta-articular and other bone defects.

Fractures of allografts. Frequency, treatment, and end-results.

One of the major complications of implantation of a massive frozen cadaveric allograft in the treatment of a tumor is fracture of the allograft. To determine the incidence, risk factors, appropriate management, and results of treatment of this complication, the records of the Orthopaedic Oncology Unit of the Massachusetts General Hospital were reviewed. Forty-three patients were identified in whom a tumor had been treated with an allograft that had subsequently fractured. The over-all incidence of fracture was almost 16 per cent. When the several risk factors (age and sex of the patient, stage and site of the lesion, and so on) for the forty-three patients who had a fracture were compared with those for the rest of the series, the only correlation was the incidence of non-union at the site of the host-donor junction, which was significantly higher in the patients who had a fracture. The mean time to fracture was 28.6 months after the operation. Three types of fractures occurred: Type I (two patients), rapid dissolution of the graft; Type II (twenty-two patients), fracture of the shaft, which was observed more frequently in male patients and which occurred a mean of 27.6 months after the operation; and Type III (nineteen patients), fragmentation of the joint, which usually occurred later (a mean of 31.6 months postoperatively) and was found more frequently in female patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnosis of infection by preoperative scintigraphy with indium-labeled white blood cells.

Scintigraphy with indium-labeled white blood cells has been reported to be sensitive and specific in the diagnosis of low-grade sepsis of the musculoskeletal system. We reviewed the records of fifty patients who had suspected osteomyelitis or suspected infection about a total joint prosthesis and who underwent scintigraphy with technetium-99m methylene diphosphonate and scintigraphy with indium-111 oxine-labeled white blood cells before an open surgical procedure. Any patient who received preoperative antibiotics was not included in the study. For all of the patients, gram-stain examination of smears, evaluation of a culture of material from the operative site, and histological examination were done. The patients were divided into two groups. Group I was composed of twenty-four patients, each of whom had a prosthesis in place and complained of pain. Group II was composed of twenty-six patients for whom a diagnosis of chronic osteomyelitis had to be considered. With the indium scans alone, there was only one false-negative result (in Group II), but there were eighteen false-positive results (eight patients in Group II and ten patients in Group I). Although scintigraphy with indium-labeled white blood cells is quite sensitive, it is not specific in detecting chronic osteomyelitis; a negative scan should be considered highly suggestive that osteomyelitis is not present. Specificity can be increased by interpreting the indium scan in conjunction with the technetium scan.

Practical considerations in the imaging of soft tissue tumors.

Cost-effective imaging evaluation of a suspected soft tissue tumor requires knowledge of all available imaging modalities, including indications for each and relative advantages and disadvantages. Imaging studies are useful in pre-treatment diagnostic evaluation, biopsy planning, and post-treatment evaluation for recurrence. Close communication between the orthopedic surgeon and radiologist is essential for appropriate management. This article will emphasize an approach to the imaging evaluation of a suspected soft tissue tumor.

Consistency of visual assessments of arch height among clinicians.

Flat feet and high-arched feet have been cited as risk factors for musculoskeletal injury and functional problems among runners and other active individuals, although there are no established quantitative definitions or measures for assessing either condition. As part of a larger study, four-plane photographs were made of the weight-bearing right foot of 246 young male Army trainees. These photographs were independently evaluated by six clinicians and rated on a scale of clearly flat-footed (category 1) to clearly high arched (category 5). There was much interclinician variability in the assessments, even for extremes of foot type. The probability of a clinician assessing a foot as clearly flat, given that another clinician had rated the foot as clearly flat, ranged from 0.32 to 0.79, with a median probability of 0.57, while for clearly high-arched feet, probabilities ranged from 0.0 to 1.00, with a median of 0.17. These findings demonstrate the need for objective standards and quantitative methods of evaluating foot morphology.

The treacherous biopsy.

The biopsy is a critical step in the evaluation of patients with suspected malignancies. The surgical approach in performing the biopsy can significantly affect the patient's future treatment options and prognosis. From July 1985 to July 1986, 63 patients were referred for evaluation by the Orthopaedic Oncology Service at Walter Reed Army Medical Center. Seven patients with primary musculoskeletal malignancies had biopsy or surgery prior to referral. In six patients this had an adverse impact on their treatment, resulting in amputation. Careful consideration of masses as potential malignancies should be undertaken prior to biopsy, and should the surgeon or the hospital be unable to provide definitive care for the patient, consideration should be given to early referral before biopsy.

Recognition and treatment of osteosarcoma in the military health care system.

Forty-two patients with high-grade intramedullary osteosarcoma treated at Walter Reed Army Medical Center between 1985 and 1995 were reviewed to determine what effects military "managed health care" had on diagnosis, treatment, and outcome. Five-year survival was 61% overall (SE +/- 9.9%), despite local disease control obtained in 95% of patients. There was a statistically significant difference between active duty members and dependents in time to diagnosis (p = 0.008), yet there was no significant difference in survival between the two groups. Five-year survival in our patient population was slightly lower than 5-year survival reported in some large civilian medical centers despite good local disease control and intensive multiagent chemotherapy. Delays in diagnosis and military status had no apparent effect on survival, although limb salvage was not possible in nearly 40% of patients because of tumor size, disease extent, and involvement of neurovascular structures.

Segmental limb reconstruction after tumor resection.

Limb salvage of large segmental and osteoarticular defects after tumor resection has become the standard of care for most patients with musculoskeletal tumors because overall survival is the same when compared with that seen in amputation patients. This study examines limb salvage for the surgical management of large segmental defects in terms of local recurrence, complications, and functional outcome in both primary and metastatic lesions. We retrospectively identified 32 patients with benign or malignant tumors of bone who underwent resection and limb salvage reconstruction by means of a custom or modular metal implant between 1985 and 1995. The most common tumor sites were the proximal femur (41%), distal femur (37.5%), and proximal humerus (12.5%). Primary bone lesions accounted for 18 patients (56%); metastatic disease accounted for 14 patients (44%). Osteosarcoma (n = 11) and chondrosarcoma (n = 3) were the most frequent primary tumors. The overall limb salvage rate (91%) was high, yet complications (28%) were common. Except for 3 patients who underwent amputation after prosthetic failure, all surviving patients were independent with or without assistive devices at latest follow-up. In patients with advanced metastatic disease, average survival was 7.6 months. No cases of aseptic loosening or implant breakage were observed in patients followed up for 2 years or more. Treatment after tumor resection with a limb salvage prosthetic reconstruction has shown good functional outcomes with an acceptable complication rate. This modality, therefore, offers patients a more favorable functional outcome with a more energy-efficient gait when compared with limb amputation.

Subtrochanteric insufficiency fractures associated with bisphosphonate use: 2 case reports and review.

Insufficiency fractures are beginning to emerge in case reports of patients on long-term bisphosphonate therapy. The side effects associated with the long-term use of bisphosphonates were once thought to only involve renal and gastrointestinal (GI) toxicity and osteonecrosis of the jaw, but it is becoming clear that the very condition bisphosphonates were meant to treat could be causing another, trading insufficiency fractures for another type of insufficiency fracture. We review the literature concerning this surprising trend in addition to providing 2 case reports and conclude that these fractures do occur, that they can heal uneventfully, and that further research is needed to determine optimum treatment algorithms concerning duration of treatment and to weigh the potential benefits and morbidity of bisphosphonate treatment.

MR appearance of fibroxanthoma.

Magnetic resonance images of nine patients with 10 fibroxanthomas of bone were retrospectively reviewed. Eight of 10 lesions were characterized by a markedly decreased signal of both T1- and T2-weighted pulse sequences. This pattern of decreased signal intensities, when present, proved distinctive and has not been observed in other nonossified primary bone lesions. Possible etiologies for this observation are discussed.

Paget disease of the anterior tibial tubercle.

A study was done of 13 cases of biopsy-proved Paget disease in which the disease involved the anterior tibial tubercle with extension into the metaphysis and diaphysis, but without apparent involvement of the proximal tibial epiphysis. Case data were obtained from archives containing more than 350 cases of Paget disease. Age, sex, symptoms, serum alkaline phosphatase level, and histologic and radiographic appearance of the lesions were evaluated. Patients were young at clinical presentation, averaging 36 years of age. In five of six patients the serum alkaline phosphatase level was normal. The proximal extent of the disease was the anterior tibial tubercle rather than the proximal epiphysis. Radiographic patterns ranged from predominantly lytic to mixed lytic and blastic to predominantly blastic, and the lesion was marginated by a flame-shaped configuration. The radiographic appearance of Paget disease of the anterior tibial tubercle is characteristic and should be sufficient to suggest the diagnosis and preclude biopsy.

MR imaging of soft-tissue masses: role of gadopentetate dimeglumine.

To assess the effectiveness of gadopentetate dimeglumine in the magnetic resonance (MR) imaging evaluation of soft-tissue masses without osseous involvement, 30 patients underwent MR imaging before and after administration of contrast material (0.1 mmol/kg). Of the 30 lesions, 22 were benign and eight were malignant; histologic confirmation was available in all lesions except one benign lesion. Overall, enhancement was detected in 26 (87%) of 30 lesions: 18 (82%) of the 22 benign lesions and eight (100%) of eight malignant lesions. Enhancement was characterized as homogeneous (two [11%] benign lesions, two [25%] malignant lesions), inhomogeneous (11 [61%] benign lesions, six [75%] malignant lesions), or peripheral (five [28%] benign lesions, no malignant lesions). Of the 19 lesions assessed for a change in enhancement over time, seven (37%) showed an increase and two (11%) showed a decrease in signal intensity. The authors conclude that benign and malignant soft-tissue lesions could not be differentiated solely on the basis of enhancement (pattern, degree, or time course).

MR appearance of fibrous dysplasia.

Magnetic resonance (MR) imaging is utilized in diverse clinical circumstances for evaluation of the musculoskeletal system. Consequently, common benign skeletal lesions may be detected incidentally following MR scan obtained for unrelated reasons. The spectrum of MR appearances of fibrous dysplasia has not been previously reported. We retrospectively reviewed all radiologic images (including the MR scans) of 11 sites of fibrous dysplasia encountered in seven patients. On MR, the fibrous dysplastic lesion causes an "expanded" bony contour and is characterized by decreased signal on T1-weighted image. The signal on T2-weighted MR scan is variable, however. Since fibrous dysplasia is a (relatively) common skeletal lesion that can be encountered incidentally, all radiologists should be familiar with its MR appearance. Furthermore, in the unlikely possibility of surgical intervention, MR is useful in determining the extent of disease within the affected bone and planning the preoperative strategy.

Intramuscular myxoma: MR features.

Intramuscular myxoma is a benign mesenchymal lesion consisting of bland spindled cells embedded in an avascular myxoid stroma. On CT, intramuscular myxoma presents as a well-demarcated, homogeneous, low density mass situated within skeletal muscle. The attenuation of the lesion is slightly greater than water but less than that of the surrounding normal muscle, with typical values between +10 and +60 HU. There is scant magnetic resonance (MR) literature on the appearance of intramuscular myxoma; the few MR spin echo images that have been published characterize it as a homogeneous mass with signal intensity less than or equal to skeletal muscle on T1-weighted and brighter than fat on T2-weighted pulse sequences. We present two cases of intramuscular myxoma with imaging characteristics that differ from those previously reported.

MR imaging findings in patients with bone-chip allografts.

Increasing use of MR to evaluate primary bone neoplasms has stimulated numerous articles on the initial assessment of these lesions. However, scant MR literature has been written about the postoperative MR appearance. We studied the MR appearance of lesions treated by curettage followed by packing with cancellous bone-chip allograft. We retrospectively reviewed the MR scans of 18 consecutive patients treated in this way. Pathologic diagnoses of these lesions were confirmed according to commonly accepted criteria. The allograft sites showed a distinctive pattern of speckled bright signal on T1-weighted images in eight cases. Thirteen of 18 grafts showed a whorled or speckled pattern of increased signal on the T2-weighted images. Only four allograft regions had predominantly low signal on both T1- and T2-weighted images. Two of 18 patients had recurrent tumor proved by open biopsy. MR images in these cases showed areas of homogeneous signal that replaced areas of speckled hyperintensity on both T1- and T2-weighted images. In both these recurrences the tumor had signal intensity similar to that seen on the preoperative MR study. We conclude that knowledge of the MR appearance of cancellous bone chip allografts is important to avoid misinterpreting areas of high signal on T1- or T2-weighted images as areas of recurrence of tumor and/or hemorrhage.