Distal Femur Allograft Prosthetic Composite Reconstruction for Short Proximal Femur Segments following Tumor Resection.

Short metaphyseal segments remaining after distal femoral tumor resection pose a unique challenge. Limb sparing options include a short stemmed modular prosthesis, total endoprosthetic replacement, cross-pin fixation to a custom implant, and allograft prosthetic composite reconstruction (APC). A series of patients with APC reconstruction were evaluated to determine functional and radiologic outcome and complication rates. Twelve patients were retrospectively identified who had a distal femoral APC reconstruction between 1994 and 2007 to salvage an extremity with a segment of remaining bone that was less than 20 centimeters in length. Seventeen APC reconstructions were performed in twelve patients. Eight were primary procedures and nine were revision procedures. Average f/u was 89 months. Twelve APC reconstructions (71%) united and five (29%) were persistent nonunions. At most recent followup 10 patients (83%) had a healed APC which allowed WBAT. One pt (8%) had an amputation and one pt (8%) died prior to union. Average time to union was 19 months. Four pts (33%) or five APC reconstructions (29%) required further surgery to obtain a united reconstruction. Although Distal Femoral APC reconstruction has a high complication rate, a stable reconstruction was obtained in 83% of patients.

Nora's lesion: bizarre parosteal osteochondromatous proliferation of the tibia.

Bizarre parosteal osteochondromatous proliferation is a rare benign condition of locally aggressive and often recurrent osteochondromatous exostosis arising from the bony cortex. We present a case of a patient who presented with this lesion in her tibia, focusing on imaging findings. Because of the lack of information on the disease's natural history, etiology, and clinical course, a multidisciplinary approach is needed for diagnosis and treatment.

Allograft-prosthetic composite reconstruction of the proximal part of the tibia. An analysis of the early results.

BACKGROUND: Allograft-prosthetic composite reconstruction of the proximal part of the tibia is one option following resection of a skeletal tumor. Previous studies with use of this technique have found a high prevalence of complications, including fracture, infection, extensor mechanism insufficiency, and loosening. To address some of these problems, we adopted certain measures, including muscle flap coverage, meticulous tendon reconstruction, rigid implant fixation, and careful rehabilitation. The goal of the present study was to evaluate the functional outcome and complications in patients undergoing allograft-prosthetic composite reconstruction of the proximal part of the tibia. METHODS: Twelve patients who underwent allograft-prosthetic composite reconstruction of the proximal part of the tibia after tumor resection were retrospectively evaluated at a median follow-up of forty-nine months. Clinical records and radiographs were reviewed to evaluate patient outcome, healing at the allograft-host junction, function, construct survival, and complications. RESULTS: Nine patients had no extensor lag, and three patients had 5 degrees to 15 degrees of extensor lag. The mean amount of knee flexion was 103 degrees (range, 60 degrees to 120 degrees ). The mean Musculoskeletal Tumor Society score was 24.3 (81%) of a maximum of 30. Complete bone union occurred in nine patients, and partial union occurred in three patients. At the time of writing, no secondary bone-grafting procedures had been required to achieve union, and no revision or removal of the reconstruction had been performed. Rotational or free flaps provided satisfactory wound coverage in all patients. A deep infection occurred in one patient whose allograft and prosthesis were successfully retained after treatment with surgical débridement and intravenous antibiotics. CONCLUSIONS: After osteoarticular resection of destructive tumors of the proximal part of the tibia, an allograft-prosthetic composite reconstruction can provide consistently good functional results with an acceptably low complication rate. Technical aspects of the procedure that may favorably affect outcome include soft-tissue coverage with muscle flaps and rigid fixation with a long-stemmed implant.

Soft-tissue sarcoma.

Soft-tissue sarcomas are rare malignancies of mesodermal origin. Common sites of involvement include the extremities, trunk, retroperitoneum, and the head and neck. Soft-tissue sarcomas of the extremities and pelvis are the most relevant to the orthopaedic surgeon. The patient with extremity soft-tissue sarcoma typically presents with a painless, enlarging mass. Advanced imaging techniques and biopsy, which are best done at tertiary referral centers, usually confirm the diagnosis. Factors such as sarcoma size, location, grade, histologic subtype, and stage, as well as patient age and comorbidities, determine the specific approach to management and patient outcome. Limb-sparing surgical resection is the mainstay of treatment. Radiation is used for unresectable tumors and as a neoadjuvant or an adjuvant to resection. The use of chemotherapy is controversial, and no standardized protocol has been established.

Effects of hypothermia on myocardial substrate selection.

BACKGROUND: Hypothermia lowers the metabolic rate and increases ischemic tolerance but the effects of temperature on myocardial substrate selection are not well defined. METHODS: Isolated rat hearts were perfused with physiologic concentrations of 13C labeled lactate, pyruvate, acetoacetate, mixed long-chain fatty acids, and glucose. Hearts were cooled over 5 to 10 minutes to one of four target temperatures (37 degrees, 32 degrees, 27 degrees, or 17 degrees C), then perfused for an additional 30 minutes, freeze-clamped, and extracted. 13C NMR spectra were obtained and substrate oxidation patterns were determined by isotopomer analysis. RESULTS: Although hearts in all groups were supplied with identical substrates, the percentage of acetyl-CoA oxidized within the citric acid cycle that arose from fatty acids decreased significantly from 53.8% +/- 0.8% in the 37 degrees C group to 33.1% +/- 3.3% in the 17 degrees C group. Lactate or pyruvate utilization increased from 3.3% +/- 0.5% to 25.7% +/- 3.6%, respectively (p < 0.05 by one-way ANOVA). CONCLUSIONS: These data suggest that moderate hypothermia suppresses fatty acid oxidation and deep hypothermia significantly increases utilization of lactate and pyruvate. These effects may result from relative inhibition of catabolism of complex molecules such as fatty acids, or stimulation of pyruvate dehydrogenase. These effects on substrate metabolism may play a role in myocardial protection afforded by hypothermia.