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Biomedical subjects

F H Sim

Publications and source records attributed to F H Sim.

At least 109 records · Page 6Linked to original sources
PubMed1993

Segmental total knee arthroplasty after distal femoral resection for tumor.

Sixty-one patients treated with custom-made segmental total knee reconstruction after resection of a primary tumor of the distal femur were reviewed retrospectively. Two types of implants were used: the Walldius hinge prosthesis (Walldius Group, n = 45) and the Kinematic rotating hinge prosthesis (Kinematic Group, n = 16). The mean periods of follow-up observation were 6.4 years for the Walldius Group and 2.3 years for the Kinematic Group. The overall functional results in the Walldius Group were excellent in 7%, good in 26%, fair in 25%, and poor in 42% of the patients. Roentgenographic analyses showed that 50% of the patients had bony resorption, 33% had interface loosening, and 10% had prosthetic stems that were broken at the time of last follow-up evaluation. Forty-two complications occurred in 34 patients who needed additional surgical treatment. Nine of the prostheses in the Walldius Group failed (20%), and 27 of the complications (64%) associated with the use of the Walldius prosthesis occurred in the first three years after implantation. Nineteen Walldius prostheses (42%) were revised or removed for reasons other than local recurrence. The overall functional results of the Kinematic Group were as follows: excellent in 25%, good in 44%, fair in 25%, and poor in 6% of the patients. Roentgenographic analysis showed that there was no change in bone on 81% of the discharge roentgenograms, that there were no radiolucent lines in 87% of the prosthetic replacements, and that there were no radiolucent lines less than 2 mm thick on the roentgenograms. None of the Kinematic rotating hinge prostheses required revision, except one with a patellar button fracture, which was revised without compromising the functional results. Four complications occurred in three patients in the Kinematic Group, and two of them required surgical treatment. The patients with the Kinematic rotating hinge prosthesis had better early functional and roentgenographic results and fewer complications.

Adolescent↗
PubMed1992

Clear cell sarcoma of soft tissues. Mayo Clinic experience with 35 cases.

Thirty-five cases of clear cell sarcoma of soft tissues were studied to determine the clinical or morphologic features that are important in predicting prognosis. Tumors occurred most commonly in the extremities, and the majority of the patients were young women. Surgery was the elected treatment in every case. Five patients experienced local recurrences, and metastases developed in 22. Fifty-four percent of the patients died of tumor, 11% are alive with disease, and the remaining 34% are alive and well; the average survival for each group was 67 months, 113 months, and 103.5 months, respectively. This sarcoma is characterized by small clusters of polygonal to spindle cells featuring clear to slightly basophilic cytoplasm and vesicular nuclei with prominent nucleoli. The clusters are separated by delicate fibrous septa. In a deletion, clear cell sarcoma has low mitotic activity, little or no necrosis, and mild nuclear pleomorphism. Tumor size and the presence of necrosis are statistically significant predictors of prognosis. All 12 patients with tumors measuring > 5 cm died of disease or are alive with disease. Eleven of the 20 patients with tumors measuring < 5 cm are alive with no evidence of disease. Tumor necrosis was present in 10 cases; eight of these patients died of disease and one is alive with disseminated metastases.

Adolescent↗
PubMed1992

General perspectives, pathogenesis, pathophysiology, and skeletal dysfunction.

A better understanding of the pathogenesis and pathophysiology of the metastatic process is leading to improvements in diagnosis and treatment. Evaluation of specific areas of disorder of skeletal function, including hematopoiesis, mineral metabolism, and structural support, is important. Continued developments are necessary to minimize or prevent effects on the skeleton related to the metastatic process.

Biomechanical Phenomena↗
PubMed1992

Metastatic disease of the femur.

Metastatic involvement of the femur is a common clinical problem and accounts for the third highest incidence after the spine and pelvis. These patients are confronted with the possibility of losing the ability to ambulate during their remaining months. However, with improved prosthetic implants and internal fixation devices, most patients can resume their previous activities after operative treatment of their femoral fractures.

Bone Nails↗
PubMed1992

Current concepts in the treatment of soft tissue sarcomas.

Soft tissue sarcomas encompass a wide variety of lesions and continue to pose a different treatment problem. However the outlook is improving. Recent advances in pre-treatment assessment and pathological assessment of soft tissue sarcomas have resulted in more accurate clinical staging. In addition, recent advances in surgical adjuvant treatment programmes hold promise for better results.

Antineoplastic Agents↗
PubMed1992

Metastatic bone disease: current concepts of clinicopathophysiology and modern surgical treatment.

Metastases to bone are a common problem confronting both the orthopaedic oncologist and cancer specialists. Early diagnosis requires a knowledge of the pathogenesis of bone metastases. A primary route of metastatic cells is via Batson's vertebral vein plexus. An understanding of the pathophysiology enables the surgeon to plan effective treatment. As many patients continue to survive for prolonged periods following the detection of bone metastases, it is important to plan treatment that is durable and functional. Non-operative treatment is utilised for small lesions (less than 25 percent of the cortical diameter). Radiotherapy (generally 3000 cGy in ten fractions), patient education (to avoid excessive torsional loads), and systemic chemotherapy or hormonal therapy are the mainstays of non-operative treatment. The indications for surgical treatment include: (1) lesions greater than 50 percent the diameter of the cortex, (2) permeative lesions in high stress areas (subtrochanteric region of the hip, mid-femoral diaphysis, mid humeral metaphysis), and (3) lesions in which pain persists following external beam irradiation. Early and effective treatment improves the remaining quality of life in patients with metastatic bone disease. A knowledge of the pathogenesis and pathophysiology aids the clinician in making an early diagnosis.

Antineoplastic Agents↗
PubMed1992

Composite fixation of salvage prostheses for the hip and knee.

A composite fixation method for a porous-coated modular segmental bone/joint prosthetic system was developed to improve fixation at revision surgery of the hip and knee after failure of the original implant with resulting massive bone loss. The porous coating is limited only to the segmental shoulder region of the prosthesis, while bone cement is used to provide initial implant stability. Autogenous bone grafts are applied over the porous-coated region to achieve extracortical bone bridging and ingrowth for long-term biologic fixation. Bench tests, theoretical analysis, and animal experiments were performed to validate this fixation concept. Clinical, roentgenographic, and functional results of revision patients using these prostheses and the underlying fixation principle are very encouraging. A number of limiting factors were identified and further improvements are being investigated to foster this concept as a viable salvage alternative.

Bone Regeneration↗
PubMed1992

Metastatic bone disease of the pelvis and femur.

Metastatic bone disease involving the pelvis and femur is a common clinical occurrence. A pathologic fracture in this region is a catastrophic event that results in significant pain and loss of function. Recent advances in surgical management of pathologic fractures, resulting in secure fracture stability or stable joint replacement, have allowed these patients to resume their pre-fracture level of activity and ambulation. The surgeon must be familiar with the various devices available, because the choice of surgical procedure depends on the location of the tumor. In selected patients with extensive destruction, methylmethacrylate can be used to enhance the security of fixation and stability. Moreover, a more aggressive approach to prophylactic fixation before a catastrophic fracture develops has distinct advantages.

Bone Neoplasms↗
PubMed1991

Desmoplastic fibroma of bone.

Desmoplastic fibroma is a rare primary tumor of bone that histologically and biologically mimics the extra-abdominal desmoid tumor of soft tissue. This study reviews 27 cases of desmoplastic fibroma, consisting of 9 from the Mayo Clinic files and 18 from our consultation files. There was a male predominance, and 74% of the patients were in the first 3 decades of life. The most frequent sites of involvement were the metaphysis of long bones and the mandible. Radiographically, the tumors were lucent, expansile lesions with well-defined margins. Histologically, they contained slender spindle cells and various amounts of collagen fibers. En bloc resection is the treatment of choice because a high incidence of recurrence was noticed after lesional curettage.

Adolescent↗
PubMed1991

Chondrosarcomas of the synovium.

Chondrosarcoma of the synovium, either primary or secondary to synovial chondromatosis, is rare. Ten cases of synovial chondrosarcoma were studied (four from the Mayo Clinic files and six from the authors' consultation files). Two were considered primary. In five cases there was evidence of preexisting synovial chondromatosis, and in the remaining three, there was a suggestion of preexisting disease. Several histologic features were found that were helpful to diagnose malignancy. The most important ones were loss of the "clustering" growth pattern typical of synovial chondromatosis, myxoid change in the matrix, areas of necrosis, and spindling at the periphery of chondroid lobules. Pulmonary metastasis developed in five of nine patients; three of these patients died.

Adult↗
PubMed1991

MR imaging of synovial sarcoma.

The MR imaging findings in 12 cases of synovial sarcoma are illustrated. The MR appearance most indicative of the tumor is an inhomogeneous septated mass with infiltrative margins located close to a joint, a tendon, or bursae, especially if soft-tissue calcification can be seen on CT scans or plain radiographs.

Adolescent↗
PubMed1991

Survival and management considerations in postirradiation osteosarcoma and Paget's osteosarcoma.

Postirradiation and Paget's osteosarcomas are high-grade malignancies. The five-year survival was only 10% in recent experience at the author's institution. Progressive pain is an important clinical feature in both conditions. Careful roentgenographic studies demonstrate cortical destruction and a soft-tissue mass in virtually all patients. Metastasis was present in 25% of both groups of patients at presentation. In contrast to previous series, more than 80% of the patients with postirradiation osteosarcoma had had irradiation for malignant entities and more than 70% had been treated with modern radiotherapy regimens (cobalt-60 or linear accelerator). Twice as many patients with postirradiation osteosarcoma were evaluated and treated in the 1980s than in the previous decade. The initial indication for irradiation often was carcinoma of the breast, uterus, or cervix, or lymphoma. Two-thirds of the patients had progressive disease that was not controllable within six months after diagnosis. Early detection may be the only effective means of improving survival with postirradiation or Paget's osteosarcoma. These patients require lifelong follow-up evaluations.

Bone Neoplasms↗
PubMed1991

Dislocation of the knee.

The results of treatment for vascular and ligamentous injuries in 17 patients who suffered complete dislocation of the knee were reviewed. Eight patients had 23 associated injuries. All nine patients who had injuries of the popliteal artery had arterial reconstruction with saphenous vein bypass grafts, which were successful in eight (89%). Intraoperative arteriography after vascular repair showed a narrowed anastomosis requiring revision in two (22%) of the nine patients and distal thrombi requiring removal in five (55%) patients. Delay in arterial repair was responsible for the one failure. Eleven patients had satisfactory results after early open ligament repair. The results were less favorable in the patients not treated with early ligament repair.

Adolescent↗
PubMed1991

Resection of malignant bone tumors about the shoulder. A preliminary report of reconstruction with a new modular spacer.

Reconstruction after resection of malignant bone tumors about the shoulder is difficult. Twelve patients had reconstruction using a new titanium modular spacer. This modular system allows the surgeon to reconstruct variable lengths of the proximal humerus. Although the patient has no active shoulder motion, excellent hand and elbow function is preserved. The spacer serves as a temporary device in the young active patient. A more definitive reconstructive procedure can be performed after the completion of chemotherapy and a sufficient disease-free interval.

Adolescent↗