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Biomedical subjects

R S Sneath

Publications and source records attributed to R S Sneath.

At least 19 recordsLinked to original sources
PubMed1999

Endoprosthetic replacement of the proximal tibia.

We have performed endoprosthetic replacement after resection of tumours of the proximal tibia on 151 patients over a period of 20 years. During this period limb-salvage surgery was achieved in 88% of patients with tumours of the proximal tibia. Both the implant and the operative technique have been gradually modified in order to reduce complications. An initial rate of infection of 36% has been reduced to 12% by the use of a flap of the medial gastrocnemius, to which the divided patellar tendon is attached. Loosening and breakage of the implant have been further causes of failure. We found that the probability of further surgical procedures being required was 70% at ten years and the risk of amputation, 25%. The development of a new rotating hinge endoprosthesis may lower the incidence of mechanical problems. Limb salvage for tumours of the proximal tibia is fraught with complications, but the good functional outcome in successful cases justifies its continued use.

Adolescent↗
PubMed1998

In vivo distraction forces in extendible endoprosthetic replacements--a study of 34 patients.

Using an instrumented distraction tool 34 extendible endoprosthetic replacements were lengthened to measure total resistance to extension. The study consisted of 19 distal femoral, 2 proximal femoral, 1 total femoral, 8 proximal tibial, 1 distal humeral, 2 proximal humeral and 1 total humeral replacements. Among these prostheses a total of 76 measurements were made. The initial load on the prosthesis due to soft tissues and muscles varied between 0 and 578 N with an overall mean of 128 N. There was a linear relationship between extension and load. At 6 mm extension the load varied between 42 and 1513 N with a mean of 476 N. There was very little difference between the means of femoral and tibial measurements. There was very little resistance to extension in the total humeral replacement due to the absence of glenoid and muscle attachment. In the distal humeral replacement all three measurements were comparable with the forces in proximal tibial replacements. Two cases showed very high resistance to extension, which was mainly attributed to the presence of large amounts of scar tissues observed at surgery. During one lengthening operation a 30 s pause at 1 mm increments from 0 to 9 mm showed load recovery of approximately 10 per cent for up to 3 mm, beyond which there appeared to be stiffening of tissues.

Adolescent↗
PubMed1997

Reconstruction of the hemipelvis after the excision of malignant tumours. Complications and functional outcome of prostheses.

We treated 35 patients with primary malignant tumours of the periacetabular area by resection and prosthetic reconstruction of the defect. At a mean follow-up of 84 months, 15 patients (43%) were free from disease. The most common complications were deep infection (26%), local recurrence (24%) and recurrent dislocation of the hip (17%). The surviving patients achieved an average of 70% of their premorbid function. This method of reconstruction has a high morbidity and should be performed only at specialist centres, but the functional and oncological outcomes are satisfactory.

Acetabulum↗
PubMed1996

Aseptic loosening in cemented custom-made prosthetic replacements for bone tumours of the lower limb.

We have made a retrospective study of 1001 custom-made prostheses used as replacements after surgery for bone tumours. There were 493 distal femoral, 263 proximal femoral and 245 proximal tibial prostheses. Aseptic loosening was shown to be the principal mode of failure of the implants, and 71 patients had revision for aseptic loosening of a cemented intramedullary stem. The probability of a patient surviving aseptic loosening for 120 months was 93.8% for a proximal femoral replacement, 67.4% for a distal femoral prosthesis and 58% for a proximal tibial implant. In patients with distal femoral replacements the age of the patient at the time of operation and the percentage of bone resected were related to the risk of aseptic loosening. Young patients with distal femoral prostheses in whom a high percentage of the femur had been replaced had the poorest prognosis for survival without aseptic loosening. The percentage of bone removed had a significant effect in the proximal tibial replacement group, but the age of the patient did not. By contrast, neither the age nor the percentage of bone removed was a factor after proximal femoral replacement. The significance of these findings is discussed in relation to mechanical factors.

Adolescent↗
PubMed1992

Computed tomographic appearances of the pelvis following hindquarter amputation.

Bilateral and midline symmetry of the normal pelvic anatomy is an aid to the interpretation of computed tomographic (CT) examinations. Following hindquarter amputation (HQA) or partial hemipelvectomy (PHP) the normal anatomical relationships are disturbed. The CT examinations of 15 patients who had undergone either an HQA or a PHP for an advanced musculoskeletal malignancy are reviewed. The new "normal" anatomy revealed displacement of the bladder and small bowel to the side of surgery in one third of patients, more commonly in the PHP cases. There were varying degrees of wasting of the ipsilateral musculature, gluteus maximus muscle flap, erector spinae and psoas muscles, etc., because of partial denervation and disruption of their origin or insertion. Recurrent tumour was identified in eight of 10 cases in which it was clinically suspected prior to the CT examination. Invariably the recurrence arose within the muscle flap at the resection margin. Bone involvement by direct tumour spread was present in three cases. Pitfalls in differentiating recurrent tumour from scar tissue are discussed.

Adult↗
PubMed1992

Endoprosthetic replacement for bony metastases.

A series of 38 patients with long bone metastases treated at the Birmingham Bone Tumour Treatment Service with resection of the metastatic lesion and replacement of the bone defect with an endoprosthesis was reviewed. The majority of cases had pathological fractures due to a massive destructive lesion. Two-thirds of the patients had a solitary metastasis. Metastases from hypernephroma and breast carcinoma accounted for the majority of cases. All the patients were independently mobile after the endoprosthetic replacement and were pain free. The average survival rate after the endoprosthetic replacement was 14.7 months and this varies with the primary tumour. The indications for endoprosthetic replacement for the treatment of long bone metastases are outlined and the results and complications are discussed. It is concluded that endoprosthetic replacement for bony metastases is an effective palliative procedure for a selected group of patients.

Adult↗
PubMed1992

Uncemented intramedullary fixation of implants using polyethylene sleeves. A roentgenographic study.

Forty-three prostheses with noncemented, high-molecular-weight, polyethylene-sleeved components were used in the treatment of bone tumors around the knee in growing children. The average age of the patients was 11 years. There were 27 boys and 16 girls. There were 17 sleeved components in the distal femur and 26 in the proximal tibia. The average follow-up time was 27 months. The roentgenograms were nominally obtained at three, six, 12, 18, and 24 months, and irregularly thereafter, and were assessed using a zonal evaluation scheme. A sclerotic interface around the polyethylene sleeves invariably developed and progressed in density up to 28 months postoperatively. There were significant zonal differences in sclerosis, particularly between the plateau and the mid-sleeve zone. Only in one patient did a sleeve become loose and require revision.

Bone Neoplasms↗
PubMed1991

Results of thoracotomy in osteogenic sarcoma with pulmonary metastases.

BACKGROUND Resection of pulmonary metastases may be followed by long term survival and now that it is an accepted method of treatment for patients with osteogenic sarcoma indicators of favourable prognosis are needed to aid the assessment of suitability for resection. This study compares the survival rates of patients who did and did not undergo resection of their pulmonary metastases and relates them to prognostic indicators. METHODS The study population was the 43 patients with osteosarcoma who developed pulmonary metastases out of the 111 patients with osteosarcoma treated by the Birmingham bone tumour treatment service during 1977-83. All patients who developed metastases confined to the lungs were considered for resection, thoracotomy being advised for all patients (provided that they were fit enough) who had metastases thought to be resectable even if they were multiple. RESULTS Of the 18 patients who did not have a thoracotomy, 15 died of disseminated disease after a mean interval of eight months; one patient died of cardiomyopathy and two are alive after 26 and eight months. Of the 25 patients who underwent thoracotomy in an attempt to resect metastases, three were found to have inoperable disease and died after a mean interval of 5.4 months from thoracotomy. Overall, after thoracotomy (repeated if necessary) there was a 20% survival at five years from the first thoracotomy. When survival was assessed with respect to the disease free interval and the number and bilaterality of the metastases no significant relationships were found. There was, however, a significant relation between survival and the position of metastases, patients with metastases confined to one lobe of the lung having a mean survival of 29.5 months, compared with 13.7 months in patients with disease in more than one lobe. CONCLUSION Thus patients who had a thoracotomy survived longer from the time of diagnosis of pulmonary metastasis than those not undergoing thoracotomy; metastases confined to one lobe predicted a better prognosis.

Adolescent↗
PubMed1991

Prosthetic replacement of the distal femur for primary bone tumours.

Over a 16-year period, 135 custom-made distal femoral prostheses, based on a fully constrained Stanmore-type knee replacement, were used in the treatment of primary malignant or aggressive benign tumours. Survivorship analysis showed a cumulative success rate of 72% at five years and 64% at seven years. Intact prostheses in 91% of the surviving patients gave good or excellent functional results. Deep infection was the major complication, occurring in 6.8% of cases; clinical aseptic loosening occurred in 6.0%. Revision surgery was carried out for loosening and infection, and the early results are encouraging. We conclude that prosthetic replacement of the distal femur can meet the objectives of limb salvage surgery.

Adolescent↗
PubMed1991

A review of 13-years experience of osteosarcoma.

Since the inception of the authors' facility, 365 patients with osteogenic sarcoma have been treated. While other facilities were surgically treating patients with primary amputation, this facility attempted limb-salvage surgery. The majority of patients being treated with limb-salvage surgery had the resected bone replaced by a metallic endoprosthetic replacement. The emphasis on conservative surgery led to the development of growing endoprosthetic replacements with the first being used in 1975. The cumulative survival of those patients with Stage 2 osteosarcoma treated at this facility between 1977 and 1984 is 48% at five years.

Amputation, Surgical↗
PubMed1990

Is bone graft necessary? Analysis of twenty cases of giant cell tumour of bone treated by curettage without graft.

Twenty cases of giant cell tumour of bone treated over an eleven year period were analysed. The minimum follow-up time was two years with an average of six years. Primary treatment consisted of a detailed curettage alone, without bone graft. A recurrence rate of 35% (7 patients) was recorded. Cases of recurrence were suitable for resection and endoprosthetic replacement. We conclude that detailed curettage alone, without bone graft, is an effective primary treatment for patients with giant cell tumour of bone.

Adolescent↗
PubMed1990

Hindquarter amputation for tumours of the musculoskeletal system.

We reviewed 34 hindquarter amputations performed for malignant tumours around the hip from 1971 to 1988, classifying them as palliative or curative according to the resection margins or the presence of disseminated disease at the time of surgery. There were three peri-operative deaths, 12 palliative and 19 curative procedures. Ten patients died of disseminated disease within a year of surgery, eight of whom had had a palliative operation. Three patients died between one and five years after palliative surgery. One died of unrelated disease at nine years. Seventeen patients are disease free an average of 31 months from surgery, 16 after curative procedures. The median survival after palliative amputations was six months and the 5-year survival rate for curative cases was 83%.

Adolescent↗
PubMed1989

Is bone grafting necessary? Analysis of twenty cases of giant cell tumour of bone treated by curettage without graft.

Twenty cases of giant-cell tumour of bone treated over an 11-year period were analysed. The minimum follow-up was 2 years. Primary treatment consisted of a detailed curettage alone, without bone grafting. A recurrence rate of 30% (six patients) was recorded. Cases of recurrence were suitable for resection and endoprosthetic replacement. We conclude that detailed curettage alone, without a bone graft, is an effective primary treatment for patients with giant-cell tumour of bone.

Adolescent↗
PubMed1989

Fatigue fractures of the femoral diaphysis in the skeletally immature simulating malignancy.

The clinical and radiological features of three fatigue fractures developing along the medial aspect of the distal femoral diaphysis are described. All three patients were skeletally immature and were referred with the radiographic diagnosis of a probable sarcoma of bone. The plain radiographic findings consisted of an uninterrupted single lamella of periosteal new bone arising medially from the distal femoral diaphysis. Bone scans showed no evidence of hyperaemia on the vascular phase and revealed a fusiform focus of increased uptake in the postero-medial cortex of the lower femoral diaphysis on the 3-h images. Computed tomography showed increased attenuation of the medulla due to fibrosis and an absence of a soft-tissue mass. Periosteal callus was present and a cortical fracture through the medial femoral cortex was identified in two cases. The features that distinguish a fatigue fracture of the femur from a sarcoma are discussed.

Adolescent↗