Search PubMed⌕ Search

Biomedical subjects

T A Damron

Publications and source records attributed to T A Damron.

At least 37 records · Page 2Linked to original sources
PubMed1999

Sparing radiation-induced damage to the physis by radioprotectant drugs: laboratory analysis in a rat model.

The radioprotectant compound amifostine (S-2[3-aminopropylamino]-ethylphosphorothioic acid), administered prior to radiotherapy, has been demonstrated to provide differential protection of normal cells from the damaging effects of ionizing radiation. The aim of this pilot was to determine if amifostine could preserve the integrity of, or minimize the damage to, the physis during exposure to radiation in an animal model. Thirty weanling Sprague-Dawley rats were randomized into five groups of six animals each. Groups 1 and 2 received a single exposure to radiation consisting of 12.5 and 17.5 Gy, respectively. Groups 3 and 4 received similar exposures of 12.5 and 17.5 Gy, respectively, but with prior administration of amifostine at 100 mg/kg. Group 5 (control) received neither radiation nor amifostine. At 6 weeks, femoral and tibial lengths were measured in treated and untreated hindlimbs and compared with the baseline lengths to calculate growth. Concordant with previous reports in the literature, the radiation doses of 12.5 and 17.5 Gy reduced net femoral growth in length by a mean of 23% (range = 12-33%, SD = 7.41) and 59% (range = 54-64%, SD = 4.45), respectively, in the irradiated limb. Amifostine reduced anticipated growth loss normally resulting from a single 12.5-Gy radiation dose by 48.9% in the femur, 13.1% in the tibia, and 27.6% overall in the total limb (p < or = 0.05). Similarly, anticipated growth loss from a single 17.5-Gy radiation dose was reduced by 30.8% in the femur, 20.3% in the tibia, and 25.7% overall in the total limb (p < or = 0.05). Amifostine administered prior to clinically relevant radiation exposures significantly reduced the amount of anticipated growth arrest in our animal model.

Amifostine↗
PubMed1999

Fibroma of tendon sheath of the infrapatellar fat pad.

We report on a 13-year-old boy who was found to have a fibroma of the tendon sheath associated with the patellar tendon and within Hoffa's fat pad of the knee. This benign tumor has never been described in this location previously. The MRI characteristics are correlated with the histologic findings.

Adipose Tissue↗
PubMed1999

Pigmented villonodular synovitis of the elbow: a case report and literature review.

Pigmented villonodular synovitis is a well-described, benign proliferative disorder of the synovium that rarely affects the elbow joint. Only 12 cases have been reported in this site. A case is presented of elbow involvement by pigmented villonodular synovitis that was documented by magnetic resonance imaging before surgery and monitored until recurrence.

Adult↗
PubMed1999

Lymphoma presenting as a soft tissue mass. A soft tissue sarcoma simulator.

Lymphoma presenting as a soft tissue mass is rare and thus may be confused with the more common soft tissue sarcoma. No previous analysis of the clinical and radiologic features of lymphomas presenting as soft tissue masses is available because most of the cases reviewed are from the pathology literature. Four patients with diagnoses of extranodal lymphomas of the soft tissues were reviewed retrospectively with respect to their clinical features, primary tumor characteristics, stage, radiographic characteristics, treatment, and followup. Mean age was 72.5 years (range, 52-85 years). The soft tissue mass occurred in the thigh (three cases) and shoulder (one case). The median size of the soft tissue mass was 6.7 cm (range, 2-15 cm) in the largest dimension, as measured on magnetic resonance imaging. These patients each had evidence of lymphadenopathy at the time of diagnosis. Lactate dehydrogenase was increased significantly in two cases and increased slightly in two other cases. One case was Stage II(E) at presentation, one was Stage III(E), and two were Stage IV. All were B cell immunophenotype. All patients died between 2 and 24 months after diagnosis, despite the use of Cytoxan, vincristine, adriamycin, and prednisone chemotherapy in each case. Clinical and radiographic features that favor extranodal soft tissue lymphoma over sarcoma include pain and tenderness, lymphadenopathy (particularly when confluent radiologically), ipsilateral extremity swelling, and elevated lactate dehydrogenase.

Aged↗
PubMed1999

Head and neck replacement prostheses in revision hip arthroplasty: experience with a single modern design.

This study reviewed 52 revision hip arthroplasties in which calcar cortical deficiencies were addressed by implantation of a cemented, modern-design head and neck replacement femoral prosthesis. Mean clinical follow-up was 38 months. Radiographic follow-up beyond 22 months was available for 34 patients (mean: 35.8 months). Mean Mayo clinical hip score (maximum: 80) improved from 28.2 preoperatively to 55.2 at last follow-up. No femoral component was revised for aseptic loosening. However, radiographic analysis demonstrated one prosthesis was probably loose and two were possibly loose. A 92.7% Kaplan-Meier 5-year implant survival rate free from radiographic loosening was projected. This type of prosthesis has yielded good clinical results and excellent early survival.

Adult↗
PubMed1999

Biomechanical analysis of prophylactic fixation for middle third humeral impending pathologic fractures.

For determination of the most biomechanically desirable construction for prophylactic fixation of impending central 1/3 humeral fractures, 24 matched pairs of fresh frozen skeletonized human cadaveric humeri were divided randomly into four groups. Group 1 compared intact humeri with matched humeri that had a 50% hemicylindrical cortical central 1/3 defect to show reproducible failure at the defect with significant reduction in strength. Groups 2 through 4 compared prophylactic fixation of the defect combined with cementation and dynamic compression plating, Rush rodding, or locked intramedullary nailing. Each specimen was tested in external rotation torsion to failure by fracture. In Group 1, test specimens with defects failed with significantly lower rotation to failure, peak torque, stiffness, and total energy absorbed to failure. In Groups 2 through 4, intramedullary nailing provided statistically significantly better total energy absorbed to failure and stiffness than did dynamic compression plating. The proximally and distally locked intramedullary nail seems to have biomechanical advantages in the prophylactic stabilization of an impending pathologic fracture of the central 1/3 of the humerus. These biomechanical findings must be considered in light of the clinical context when a means of fixation is selected.

Analysis of Variance↗
PubMed1998

Intracortical chondroma.

A case of a 45-year-old woman with an intracortical chondroma of the right tibia is described. The uniqueness of this location and presentation is discussed.

Bone Neoplasms↗
PubMed1998

Benign fetal rhabdomyoma of the upper extremity. A case report.

Benign fetal rhabdomyoma is a tumor of striated muscle origin that rarely is seen in the extremities. Because of the similarities of fetal rhabdomyoma to its malignant counterpart, rhabdomyosarcoma, an important distinction is to be made to avoid errors in treatment. The clinical presentation, radiographic, and pathologic features of the first known case of an isolated upper extremity rhabdomyoma are described. The authors discuss, the distinction between this and rhabdomyosarcoma and also describe a unique histologic feature in rhabdomyoma, the presence of psammoma bodies.

Arm↗
PubMed1998

Head and neck replacement endoprosthesis for pathologic proximal femoral lesions.

Records of 28 patients with pathologic lesions in the proximal femur treated by implantation of a femoral head and neck replacement prosthesis between 1984 and 1995 were reviewed. Mean clinical followup was 47.8 months in the eight living patients and 15.8 months in the 20 patients who had died. The underlying diagnosis was metastatic disease or myeloma in 22 patients. The most frequently occurring indication for implantation of this device was a pathologic fracture in 26 patients (18 displaced, eight impending), followed by resection and reconstruction in two patients. All femoral components were cemented: 23 were bipolar hemiarthroplasties and five were total hip arthroplasties. Implant survivorship was good (93%), with only two prostheses removed during the followup period, both for infection. However, radiographic analysis revealed increasing lucencies with time, particularly in the most proximal zones, resulting in radiographic failure in an additional case. Deep infection occurred in three cases, leading to resection arthroplasty in two patients. Periprosthetic fractures occurred in three cases, but only one occurred intraoperatively. Despite a high complication rate, the good implant survival during the shortened life span of these patients supports the continued use of femoral head and neck replacement prostheses in this population.

Adult↗
PubMed1998

Functional laboratory assessment after oncologic shoulder joint resections.

A laboratory evaluation was undertaken to assess the shoulder range of motion and distal strength after oncologic resection and reconstruction involving the shoulder joint and to compare these functional parameters based on potentially important variables. Inclusion in the study was limited to 32 patients with bone tumors of the proximal humerus or scapula treated surgically by resection of the shoulder joint including the proximal humerus from 1976 through 1992. Active shoulder range of motion and isometric elbow extension and forearm supination strength are significantly less after surgery in patients with greater amounts of bony resection and with resection of the deltoid. Patients who had a modified Tikhoff-Linberg resection were able to achieve 10 degrees to 15 degrees greater shoulder motion in each direction than were patients who had the classic procedure including complete scapulectomy. However, elbow flexion and extension strength and forearm pronation strength were greater for the patients with the classic resection. Osteoarticular allografts as a reconstructive alternative provide as a group the best shoulder motion and overall distal upper extremity strength, but these reconstructions were performed only when the rotator cuff muscles and deltoid were able to be reconstructed. Diminishing elbow strength was seen with longer followup in the patients with osteoarticular reconstructions, corresponding temporally to subchondral collapse observed on radiographs. Range of shoulder motion except rotation was just as good for allograft vascularized fibular arthrodeses as for the osteoarticular allografts, but strength was significantly less with the arthrodeses.

Adolescent↗
PubMed1997

Effects of stem length on mechanics of the femoral hip component after cemented revision.

Bone loss in the proximal femur at the time of revision hip arthroplasty for a failed primary cemented femoral component can substantially reduce the stability of the revision stem. Use of an extended-length femoral component has been suggested to aid in achieving long-term fixation; however, the optimal stem length is unknown. A three-dimensional finite element model of a Charnley-type revision femoral component in a sclerotic shell of cortical bone devoid of cancellous bone was developed, and five different stem lengths ranging from 140 to 273 mm were used. The interface between the sclerotic bone and cement mantle consisted of fibrous tissue. Distal to the sclerotic bone, bonding was allowed between the cement and bone. Relative motion between the cement and bone was reduced substantially when the stem extended beyond the original defect. Maximum principal stresses in the proximal cement mantle decreased from 7.7 to 5.5 MPa, but cement stresses near the distal tip increased from 7.9 to 10.7 MPa when the stem just bridged the defect. Further increases in stem length reduced the distal cement stresses. Increases beyond two femoral diameters had a minor effect on changes in relative motion, cement mantle stresses, and stresses across the cement-bone interface. The results suggest that a femoral component that extends beyond the area of cancellous bone defect by two femoral diameters will be most effective in minimizing stresses and motion that could be associated with clinical loosening of the cemented revision. A shorter stem that just bridges the cancellous bone defect left from the primary procedure may not provide adequate distal fixation due to high cement-bone shear stresses.

Biomechanical Phenomena↗
PubMed1997

En bloc resection of tumors of the distal end of the ulna.

The operative treatment of malignant tumors and aggressive benign tumors involving the distal end of the ulna often necessitates en bloc resection. The oncological and functional results for eight patients in whom a neoplasm involving the distal end of the ulna had been treated with en bloc resection without reconstruction of the osseous defect were reviewed retrospectively at a mean of seventy-nine months (range, twenty-three to 271 months). Four patients had a giant-cell tumor; two, a low-grade osteogenic sarcoma; one, a hemangioendothelioma; and one, a soft-tissue epithelioid sarcoma with osseous involvement. The amount of bone that was removed from the distal end of the ulna ranged from 3.1 to 9.0 centimeters. In the four patients who had a malignant tumor, a minimum of 7.5 centimeters was removed in order to achieve an adequate wide margin proximally. In the patients who had a benign tumor, a maximum of 6.6 centimeters was resected. Extraperiosteal resection was performed in three of the patients who had a malignant tumor and in one of the patients who had an aggressive giant-cell tumor. Subperiosteal resection was performed in the three patients who had a benign tumor and in one patient who had a parosteal osteogenic sarcoma. None of the patients had local or systemic evidence of recurrence of the tumor. The functional result was excellent for six patients and good for two. Grip strength was reduced by a mean of 15 per cent compared with the strength on the contralateral side, and this reduction did not appear to be related directly to the amount of bone that had been resected. The findings of this study support the concept that routine reconstruction of the osseous defect is not necessary after en bloc resection of a neoplasm of the distal end of the ulna.

Adult↗
PubMed1997

Unusual manifestations of proximal tibiofibular joint synovial cysts.

Synovial cysts emanating from the proximal tibiofibular articulation are commonly symptomatic and may progress to compromise peroneal nerve function. They may cause diagnostic confusion when they present as intraosseous masses or as soft tissue masses causing extrinsic bony erosion. Twelve cases treated surgically are reviewed. Electromyography and nerve conduction studies were valuable in localizing the lesions to the knee when no mass was palpable. Of the six cases involving the peroneal nerve, three required loupe or microscopic dissection of the cyst from within the epineurium. Two other cases had bony changes. Magnetic resonance imaging, though not diagnostic, is valuable in planning the dissection.

Aged↗
PubMed1996

Intercalary spacers in the treatment of segmentally destructive diaphyseal humeral lesions in disseminated malignancies.

During a 10-year period, 17 patients with segmentally destructive bone lesions of the humeral diaphysis in disseminated malignancies resulting in impending fracture (8 patients), pathologic fracture (6 patients), or failure of attempted internal fixation techniques (3 patients) were treated with resection of the involved diaphyseal segment and reconstruction with a cemented modular intercalary humeral spacer. Fourteen patients had metastatic cancer, 2 had multiple myeloma, and 1 had lymphoma. Breast and renal carcinoma were the most common pathologic diagnoses. The involved site was within the middle 1/3 in 8 patients, in the proximal-middle junction in 5, in the middle-distal junction in 2, and within the proximal and distal 1/3 in 1 patient each. Early pain relief was successful in 88% of patients. Early in the postoperative hospital course, patients generally were able to use the ipsilateral hand to assist feeding. Radiographic analysis revealed that the limited selection of stem lengths led to 76% of the distal stems and 47% of the proximal stems being shorter than the ideal length. The complication rate independent of disease progression was 29%. The most common complication was temporary radial nerve injury (3 patients). There were 3 implant failures, most commonly due to disengagement of the male-female junction. Two periprosthetic fractures occurred, 1 proximally (due to tumor progression) and 1 distally. Suggestions are given for modification of the implants to improve the major problems of limited versatility in intramedullary stem length and inadequate mating at the junction.

Adult↗
PubMed1996

Multicentric chondrosarcomas.

Multicentric chondrosarcomas, other than those from mesenchymal chondroma, are rare and difficult to differentiate from metastatic disease. Eight new patients with multicentric chondrosarcomas are reported. Five patients had chondrosarcomas that were monomelic, 3 had disseminated chondrosarcomas, 3 had synchronous involvement, and 5 had metachronous involvement; 1 patient had Ollier's disease. A bimodal age distribution was apparent: 4 patients were between 62 and 76 years old, and the remaining 4 were between 16 and 33 years old. Average duration of followup was 6 years, 4 months. Each of the patients with synchronous chondrosarcomas had single bone lower extremity involvement and presented with symptoms occurring at only 1 of the 2 sites of tumor. Each of the 5 patients with metachronous chondrosarcomas experienced involvement of a different bone when the second tumor presented. Only 1 of these metachronous chondrosarcomas was limited to the lower extremity. The second tumor occurred in all patients after excellent control of the primary tumor by wide excision. The average duration between diagnosis of the 2 tumors was 4 years, 4 months (range, 8 months-12 years, 9 months). Patients who had nonmonomelic malignancies must be viewed with a considerably more guarded prognosis than those who had monomelic chondrosarcoma because each of the 2 deaths resulting from progressive disease occurred among the 3 patients with nonmonomelic chondrosarcoma. The nonmonomelic malignancies may represent metastatic chondrosarcoma with a rare predilection to bony involvement. Monomelic chondrosarcoma simply may represent lesions analogous to the skip lesions observed in osteosarcoma.

Adolescent↗
PubMed1996

Ewing's sarcoma of the proximal femur.

The cases of 16 patients with Ewing's sarcoma of the proximal femur treated in the era of multiagent chemotherapy were reviewed, with emphasis on the mechanical problem of tumor involvement in this structurally demanding site. Fourteen patients received chemotherapy and local radiotherapy as the initial primary treatment. One patient had chemotherapy and radiotherapy, followed by wide local resection. One patient had amputation, followed by chemotherapy, for pathologic fracture and extensive soft tissue involvement at presentation. Two local recurrences occurred. Excluding the 2 patients whose femurs were fixed prophylactically, the pathologic fracture rate was 79%. In addition, by excluding the 2 patients who died before fracture, the pathologic fracture rate was 92%. Nonunion occurred in 5 (71%) of the 7 pathologic fractures not treated by resection and required as many as 5 additional surgical procedures to obtain union. At latest followup evaluation (average, 6.3 years), 10 patients had no evidence of disease, 1 was alive with disease, and 5 had died of their disease. Options for management should include primary resection and reconstruction or prophylactic internal fixation after completion of chemotherapy plus or minus radiotherapy.

Adolescent↗