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Biomedical subjects

S R Cannon

Publications and source records attributed to S R Cannon.

At least 55 records · Page 3Linked to original sources
PubMed1998

Use of extendable total femoral replacements in children with malignant bone tumors.

Although rarely required, extendable reconstruction devices for replacing the entire femur offer children with malignant bone tumors the opportunity of a nearly normal development by overcoming an expected leg length discrepancy. Femoral integrity can be restored, allowing most patients to walk without the use of aids. There are no data available to provide evidence regarding long term results and morbidity in such patients. Six patients (range 2-12 years of age), three with osteogenic osteosarcoma and three with Ewing's sarcoma, were treated between 1988 and 1996 with custom made Stanmore extendable prosthetic total femoral replacements. One patient died 12 months after surgery because of complications relating to pulmonary metastasis. The remaining five patients were observed between 2.7 and 8.9 years (average, 5 years). No tumor recurrence has been recorded and no amputation has been performed. All surviving patients underwent an average of 9.4 operative procedures (range, 4-16 procedures) including 6.4 extension procedures (range, 3-10 procedures), and one prosthetic revision (range, 0-3 procedures). Five revisions in two patients were necessary because of infection, loosening of the prosthesis, mismatch between femoral head and acetabulum, or full extension of the extending mechanism. The functional results were measured in accordance with the Musculoskeletal Tumor Society rating score, with an average result of 77.3%. Total femoral replacement in a growing individual achieves good functional results yet has various risks for an uncertain outcome. Careful selection of the patient and realistic appraisal of the long term prospects are essential for successful treatment.

Bone Neoplasms↗
PubMed1997

Telemetry of forces from proximal femoral replacements and relevance to fixation.

Two proximal femoral replacements were instrumented to enable axial forces to be determined at two sites within the prosthesis: in the main shaft and near the tip of the intramedullary stem. The goal was to measure the changes in force distribution over time, as indicated by the ratio of the two forces. Inductive coupling between a coil worn around the leg and a small implanted coil was used, both to supply power to electronic circuits sealed into a welded cavity in the prosthesis and to telemeter data from the prosthesis. Data from both subjects were recorded over the first two years following surgery. For the first subject, there was an increase in mean shaft force excursions (peak force minus resting force) during level walking from 0.53 x BW after 1 week 2.77 x BW after 23 months. The corresponding mean tip force excursions were 0.13 x BW and 1.74 x BW, respectively. The ratio of mean tip force excursions to shaft force excursions steadily increased over the same period from 25 to 63%. Similar increases over time in the tip/shaft ratio were found during treadmill walking, stair climbing and stair descending. Data from the second subject were obtained for the shaft forces only, and were consistent with those from the first subject. The progressive transfer of axial load from the proximal to the distal part of the IM stem recorded telemetrically, together with radiographic observations, suggested that bone remodelling had taken place together with a less stable interface around the proximal part of the stem. This process evidently began soon after implantation.

Bicycling↗
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↗
PubMed1997

Stanmore custom-made extendible distal femoral replacements. Clinical experience in children with primary malignant bone tumours.

The use of extendible distal femoral replacements is a relatively new treatment alternative for malignant bone tumours in growing individuals. Although their appearance was widely appreciated, questions about functional practicality and longevity remain unclear. With longer follow-up, advantages of immediate functional restoration and beneficial psychological aspects seem to be overshadowed by an increase in complications such as aseptic loosening, infection or prosthetic failure. We have reviewed 18 children with such tumours who were treated between 1983 and 1990 by custom-made Stanmore extendible distal femoral replacements. Four died from metastatic disease within 2.5 years of operation and two required amputation for local recurrence or chronic infection. The remaining 12 patients were followed for a mean of 8.7 years (6 to 13.2). A mean total lengthening of 5.2 cm was achieved, requiring, on average, 4.3 operations. Using the Musculoskeletal Tumor Society rating score the functional result at review was, on average, 77% of the expected normal function, with seven patients achieving > or = 80%. Revision of the prosthesis was required in ten patients, in six for aseptic loosening, at a mean of 6.2 years after the initial procedure.

Adolescent↗
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↗
PubMed1990

Parosteal osteosarcoma. Treatment by wide resection and prosthetic replacement.

We have reviewed 20 cases of parosteal osteosarcoma treated by wide local resection and prosthetic replacement and followed up for six to 17 years. Limb function was excellent in 85%. One patient with grade III histological disease developed pulmonary metastases. Four patients had local recurrences, which were related to repeated preliminary biopsies, inappropriate siting of biopsy and vascular encroachment by the tumour. After this mode of treatment, the outcome was not related to medullary invasion by the tumour.

Adolescent↗
PubMed1989

Is arthroscopy always necessary?: a waiting list review.

Eighty-seven patients who had been on a waiting-list for an arthroscopy of the knee for longer than one year were reviewed. Eleven of them were found to have already been operated on. Only 28 of the remaining 76 patients had continued to suffer symptoms of sufficient severity that they wished to proceed to surgery. Symptoms had remitted in 69% of patients with degenerative disease or suspected meniscal pathology without ligamentous instability. Nine out of 10 patients with ligamentous instability, with or without meniscal tears, elected to proceed to surgery. These findings may be relevant when considering the selection of patients for arthroscopy, and when reviewing the results of arthroscopic surgical procedures.

Adult↗
PubMed1988

Inadequacy of the Gorlin formula for predicting prosthetic valve area.

A total of 135 patients with normally functioning prosthetic aortic valves who were catheterized 6 months after placement of Hancock, modified Hancock or Bjork-Shiley prostheses were studied to determine the magnitude of error in Gorlin formula estimates of prosthetic aortic valve area. All patients were male, selected from 13 participating hospitals and routinely followed after valve replacement for 5 years. Hemodynamically determined Gorlin valve areas were compared with independently verified actual valve areas. Actual Hancock areas were measured from videotapes of valves exercised in a pulse duplicator flow model. Actual Bjork-Shiley areas were calculated directly from the valves' inner ring radius. Gorlin valve areas correlated poorly with actual valve areas (r = 0.39). The mean Gorlin formula error was 0.36 cm2 (standard deviation = 0.32). Gorlin areas overestimated actual areas by greater than 0.25 cm2 in 43 patients (32%) and underestimated actual areas by greater than 0.25 cm2 in 29 (21%). It was concluded that the Gorlin formula inaccurately predicts prosthetic valve area in the aortic position. Overreliance on this formula in assessing aortic stenosis could lead to errant clinical decisions.

Aortic Valve↗
PubMed1988

Pseudomembranous colitis associated with antibiotic prophylaxis in orthopaedic surgery.

We report 16 orthopaedic patients who had antibiotic-associated diarrhoea (pseudomembranous colitis) after operation. There was an association with the use of cephradine and with the prolongation of prophylaxis for more than three peri-operative doses. Five cases occurred as a cluster, suggesting that the causative agent, Clostridium difficile, may be infectious in some situations.

Adult↗
PubMed1988

Malignant fibrous histiocytoma: the most common soft-tissue sarcoma.

Although soft-tissue sarcomas account for less than 1% of all malignancies, over 55 different histological variants have been described. Consequently clinicians often find the classification both complex and confusing. A new variant, the malignant fibrous histiocytoma (MFH), is now the most common adult soft-tissue sarcoma, therefore a clear understanding of the diagnosis, its implications and the optimum treatment is desirable.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1987

The Colonna-Hey Groves arthroplasty in the late treatment of congenital dislocation of the hip. A long-term review.

Forty-four patients who had undergone 50 capsular arthroplasties for congenital dislocation of the hip were reviewed after a mean follow-up of 20 years. Their average age at operation was 5.9 years; 31 of the operations were undertaken because of late presentation, the remainder because of the failure of previous surgery. In all, 70% of the hips showed good function despite a reduced range of movement, but patients with bilateral arthroplasties fared poorly. Excellent containment within the acetabulum was found in 80%, but the femoral head was always abnormally high though not unduly lateral or medial. This configuration had remained unchanged during follow-up. The accuracy of reduction along the mediolateral axis was the only variable found to influence the outcome significantly. Functional deterioration, associated with pain, was noted to be more common after 20 years than before, and was associated with radiographic evidence of joint degeneration.

Child↗
PubMed1986

Breakdancer's back.

We report a case of a painful soft tissue swelling in the thoracolumbar region of the spine of a breakdancer, which caused serious diagnostic difficulty because of coexisting congenital absence of a transverse process of the first lumbar vertebra.

Back Pain↗
PubMed1986

A long-term study following Bennett's fracture.

Twenty-five patients with documented Bennett's Fractures were reviewed five to sixteen years following injury (Mean 9.6 years). The majority of fractures affected the dominant hand and occurred in males. Twenty-two patients were managed conservatively by plaster immobilisation. At review ten patients were asymptomatic and only two had significant symptoms. Examination revealed loss of movement in the trapeziometacarpal joint of the thumb in twenty-one cases. Five of these exhibited malrotation of the thumb. Review of the post reduction radiographs revealed separation of the fragments by 1 mm or more in sixteen patients, but symptoms at follow-up could not be correlated with accuracy of reduction. Twenty-three patients had a varus angulation of the first metacarpal base which could be correlated to the initial post-reduction displacement. There was no correlation with the restriction of movement. Although metacarpal length will only be maintained by reduction of the fracture, there was little evidence that imperfect reduction leads to significant symptomatic arthritis in the long term.

Adolescent↗
PubMed1986

Calculation of aortic valve area by Doppler echocardiography: a direct application of the continuity equation.

The continuity equation suggests that a ratio of velocities at two different cardiac valves is inversely proportional to the ratio of cross-sectional areas of the valves. To determine whether a ratio of mitral/aortic valve orifice velocities is useful in determining aortic valve area in patients with aortic stenosis, 10 control subjects and 22 patients with predominant aortic stenosis were examined by Doppler echocardiography. The ratio of (mean diastolic mitral velocity)/(mean systolic aortic velocity), (Vm)/(Va), and the ratio of (mitral diastolic velocity-time integral)/(aortic systolic velocity-time integral), (VTm)/(VTa), were determined from Doppler spectral recordings. Aortic valve area determined at catheterization by the Gorlin equation was the standard of reference. High-quality Doppler recordings were obtained in 30 of 32 subjects (94%). Catheterization documented valve areas of 0.5 to 2.6 (mean 1.1) cm2. There was good correlation between Doppler-determined (Vm)/(Va) and Gorlin valve area (r = .90, SEE = 0.23 cm2); a better correlation was noted between (VTm)/(VTa) and Gorlin valve area (r = .93, SEE = 0.18 cm2). The data demonstrate the usefulness of Doppler alone in the determination of aortic valve area in adults with absent or mild aortic or mitral regurgitation and no mitral stenosis. Although the use of mean velocity and velocity-time integral ratios requires accurate measurement of mitral and aortic velocities, it does not require squaring of these velocities or measurement of the cross-sectional area of flow.

Adult↗
PubMed1986

Massive osteolysis. A review of seven cases.

Seven cases of massive osteolysis are presented. The aetiology of this disease is as yet unknown; neither age nor sex seems to be a factor in its incidence, nor are standard bone grafts or radiotherapy successful methods of treatment. However, in this series, operation produced a satisfactory outcome for five patients at a mean follow-up of 17 years; in three of these patients a custom-built prosthesis was inserted, and in one a conventional bone graft was combined with intramedullary nailing.

Adolescent↗
PubMed1986

Recurrent dislocation of the hip with a "Bankart-type" lesion.

A patient with recurrent dislocation of the hip is described. The initial injury had been a posterior dislocation without associated fracture of the acetabular wall, and the hip had not been immobilised or protected from weight-bearing during treatment. Exploration of the hip for recurrence revealed disruption of the posterosuperior acetabular labrum with formation of a pouch between the posterior acetabular wall and the short rotator muscles. We have found no previous report of this lesion, which resembles a Bankart lesion of the shoulder. Repair using a bone block is described.

Adult↗