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Biomedical subjects

R Sekel

Publications and source records attributed to R Sekel.

13 recordsLinked to original sources
PubMed2005

Computational bone remodelling simulations and comparisons with DEXA results.

Femoral periprosthetic bone loss following total hip replacement is often associated with stress shielding. Extensive bone resorption may lead to implant or bone failure and complicate revision surgery. In this study, an existing strain-adaptive bone remodelling theory was modified and combined with anatomic three-dimensional finite element models to predict alterations in periprosthetic apparent density. The theory incorporated an equivalent strain stimulus and joint and muscle forces from 45% of the gait cycle. Remodelling was simulated for three femoral components with different design philosophies: cobalt-chrome alloy, two-thirds proximally coated; titanium alloy, one-third proximally coated; and a composite of cobalt-chrome surrounded by polyaryletherketone, fully coated. Theoretical bone density changes correlated significantly with clinical densitometry measurements (DEXA) after 2 years across the Gruen zones (R2>0.67, p<0.02), with average differences of less than 5.4%. The results suggest that a large proportion of adaptive bone remodelling changes seen clinically with these implants may be explained by a consistent theory incorporating a purely mechanical stimulus. This theory could be applied to pre-clinical testing of new implants, investigation of design modifications, and patient-specific implant selection.

Absorptiometry, Photon↗
PubMed1998

Hip fracture in elderly men: the importance of subclinical vitamin D deficiency and hypogonadism.

OBJECTIVE: To determine the major risk factors for hip fracture in elderly men. DESIGN: Prospective recruitment, followed by analysis of clinical and biochemical variables. PATIENTS AND SETTING: Men aged 60 years and older who presented to St George Hospital (a 650-bed tertiary-care centre) in 1995, comprising all 41 men with hip fractures, as well as 41 hospital inpatient and 41 outpatient control subjects without hip fractures. MAIN OUTCOME MEASURES: Osteoporotic risk factors (including age, body weight, comorbid illnesses, alcohol intake, cigarettes smoked, and corticosteroid use) and serum concentrations of creatinine, urea, calcium, albumin, alkaline phosphatase, parathyroid hormone, 25-hydroxyvitamin D and free testosterone. RESULTS: There were no significant differences between the hip fracture and two control groups on any of the osteoporotic risk factors. Men with hip fracture had significantly lower mean serum 25-hydroxyvitamin D concentration (45.6 nmol/L; 95% confidence interval [CI], 36.9-52.3 nmol/L) than both inpatient (61.1 nmol/L; 95% CI, 50.0-72.2 nmol/L) and outpatient (65.9 nmol/L; 95% CI, 59.0-72.8 nmol/L) controls (P=0.007). Subclinical vitamin D deficiency (defined as <50 nmol/L serum 25-hydroxyvitamin D) was 63% in the fracture group, compared with 25% in the control groups combined (odds ratio, 3.9; 95% CI, 1.74-8.78; P=0.0007). Inpatients with and without hip fractures had significantly lower mean serum albumin, calcium and free testosterone concentrations than outpatients (P< 0.05). In a multiple regression analysis, subclinical vitamin D deficiency was the strongest predictor of hip fracture (beta [regression coefficient], 0.34+/-0.19; P=0.013). CONCLUSIONS: Subclinical vitamin D deficiency in Australian men may contribute significantly to the development of hip fracture through the effects of secondary hyperparathyroidism, resulting in increased bone loss.

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PubMed1998

Familial slipped capital femoral epiphysis: a report and considerations in management.

BACKGROUND: Familial inheritance of slipped capital femoral epiphysis (SCFE) is known. It has not been described in non-identical twins. A family where the mother and three of five siblings developed SCFE were investigated and managed. METHODS: Anthropometric measurement consisted of height-weight ratios. Serum sex hormone levels and bone Gla Protein was measured. Bone mineral densities were evaluated. RESULTS: The affected siblings had higher bodyweight percentiles. Other investigations were within normal limits. CONCLUSION: The unfavourable height-to-weight ratio was one of the mainstays in developing a management protocol for all siblings. The management protocol developed for the family is discussed.

Algorithms↗
PubMed1997

Hip fracture in elderly men: prognostic factors and outcomes.

OBJECTIVE: To examine prognostic factors and outcomes after hip fracture in men aged 60 years and older. DESIGN AND SETTING: Cohort study of all men presenting to St George Hospital (a 650-bed tertiary care centre) with hip fractures in 1995, recruited retrospectively from medical records and evaluated prospectively at six and 12 months after fracture. PATIENTS: 51 men aged 60 years or more (and, for comparison, 51 age-matched women) who presented with hip fracture not caused by high impact injuries or local bone disease. MAIN OUTCOME MEASURES: Prognostic factors (such as pre-existing illness and osteoporotic risk factors) and outcome data (such as fracture-related complications, mortality, and level of function as measured by the Barthel index of activities of daily living at six and 12 months postfracture). RESULTS: Median age of the 51 men was 80 years (interquartile range, 74-86 years); four were aged under 70 years. Outcome assessment was possible for 41 men (80%). Similar proportions of men and women came from institutions (32% v. 28%), and similar additional proportions required institutionalisation after discharge (18% v. 14%). Fracture-related complications affected similar proportions of men and women (30% v. 32%), and mean length of hospital stay was similar. Fourteen per cent of men died in hospital compared with only 6% of women (P = 0.06). Men had more risk factors for osteoporosis (P < 0.01). Physical functioning (measured by the Barthel index) deteriorated significantly in men from 14.9 at baseline to 13.4 at six months (P < 0.05) and 12.4 at 12 months (P < 0.05) after fracture. CONCLUSION: Compared with women, elderly men presenting with hip fracture have higher mortality and have more risk factors for osteoporosis. Like women with hip fracture, men are usually fragile, with pre-existing medical illness and fracture-related complications contributing to their overall poor outcomes.

Activities of Daily Living↗
PubMed1996

Measurement of periprosthetic bone density in hip arthroplasty using dual-energy x-ray absorptiometry. Reproducibility of measurements.

To define the precision (reproducibility) of measurement of periprosthetic bone mineral density and bone mineral content, dual-energy x-ray absorptiometry scans were obtained on 45 randomly selected patients who had had a unilateral total hip arthroplasty within the previous 3 years. The coefficients of variation of the bone mineral density in the proximal Gruen zones were 5.0 and 5.3%, corresponding to errors of 0.07 and 0.11 g/cm2. The coefficients of variation of the bone mineral density for the distal zones averaged 2.8%, with an error of 0.08 g/cm2. The coefficients of variation of the bone mineral content were 4.8 and 2.9% for the proximal and distal zones. The contralateral femur was also scanned in 32 of the patients. For the contralateral femur bone mineral density, the coefficients of variation were 5.0% for the proximal zones and 4.8% for the distal zones. The bone mineral content was 6.0% for the contralateral regions. These results imply that differences in bone mineral density greater than 0.16 g/cm2 (2 standard errors) can be reliably measured. Dual-energy x-ray absorptiometry therefore provides a highly reproducible technique for quantitatively monitoring the changes in bone density that occur after total hip arthroplasty.

Absorptiometry, Photon↗
PubMed1995

An unusual cause of thigh pain after total hip arthroplasty.

The aim of total hip arthroplasty surgery is to relieve pain. There are many postulated causes of thigh pain following total hip arthroplasty, some of which are not easily corrected. Muscle hernia as a result of hip surgery is a cause of thigh pain that is disabling, relatively easy to diagnose, and may be preventable.

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PubMed1994

Supracondylar fractures above a total knee arthroplasty. A novel use of the Huckstepp nail.

A displaced supracondylar fracture of the femur above a total knee arthroplasty (TKA) was treated with a Huckstepp intramedullary nail (Down Surgical, Mitcham, Surrey). The nail was firmly engaged over the tip of the intramedullary stem of the femoral component, establishing fracture alignment and providing enough stability against displacement, angulation, and shortening to allow fracture union. This technique can be applied to any periprosthetic fracture involving a stemmed femoral component.

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PubMed1991

Autograft and Leeds-Keio reconstructions of the ovine anterior cruciate ligament.

This study compared the Leeds-Keio prosthesis with grafting of autogeneic patellar tendon for the reconstruction of the ovine anterior cruciate ligament under controlled conditions. Reconstructed knees from six sheep of each group were evaluated at 12, 26, and 52 weeks postreconstruction with respect to clinical assessment, gross pathology, mechanical properties, and histology. Although no difference in clinical assessment (anteroposterior draw, range of motion, and function) was noted between the prosthesis reconstruction and the autograft reconstruction, the prosthesis provided a higher strength initially, which remained relatively constant over the one-year study. However, prosthesis wear was observed, with up to 50% of Dacron fibers ruptured in some cases. Histologic sections indicated that in the ovine model, the Leeds-Keio prosthesis should be considered an artificial device and not a scaffold or stent that supports aligned collagenous growth. The autograft had low strength at 12 weeks, which increased over the study period. Despite acceptable clinical performance and adequate mechanical properties up to one year postimplantation, neither reconstruction approached the clinical or mechanical performance of the normal anterior cruciate ligament in the ovine model.

Animals↗
PubMed1977

Flexor tendon repair in "No Man's Land" an experimental study.

Twenty-five fingers of seven monkeys were used for an experimental study of a new concept of flexor tendon repair in "No Man's Land". Microsurgical aids were used to shift distally a sleeve of healthy flexor tendon sheath to cover the site of the repaired flexor tendon. There was a low success rate due to technical difficulties in the immobilisation of the monkey fingers. Where the finger was successfully immobilised the results were encouraging.

Animals↗