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Biomedical subjects

J D Wark

Publications and source records attributed to J D Wark.

116 records · Page 7Linked to original sources
PubMed1979

Osteomalacia due to unusual causes presenting in adults.

Severe osteomalacia due to causes other than malabsorption and, where renal function was impaired, disproportionate to the degree of renal failure, is described in 15 adults. Only one was younger than 46 years, the median age being 59 years. The diagnosis was not made for months in most patients. After investigation, the patients were grouped as follows: nutritional three cases, "renal" six cases, hypophosphataemia three cases, neurofibromatosis and primary hyperparathyroidism one each. The last patient was poorly nourished and had taken anticonvulsants and analgesics. Most patients responded well to treatment with calciferol. These cases indicate the need to be aware that osteomalacia may occur in previously healthy middle-aged or elderly subjects.

Adult↗
PubMedDate not supplied

Effects of resistance training on bone parameters in young and mature rats.

1. Osteoporosis is a major public health problem that is predicted to worsen over the next decade and preventative strategies that increase bone strength have become the focus of substantial research. 2. Although mechanical load is a primary factor in the acquisition and maintenance of skeletal tissue, the type of exercise used and when in life it is most effectively prescribed remain inconclusive. 3. The present study compared 10 weeks of resistance training in both young and mature female Sprague-Dawley rats and measured bone density and body composition by dual energy X-ray absorptiometry and biomechanical properties by three point bending tests of the tibia and femur. 4. No significant differences were observed for any of the bone parameters when comparing exercise and control groups at either age. This was despite using a comparable training protocol to that in humans and using loads of approximately 150% bodyweight. 5. The present study concludes that more intensive work programmes of resistance training or different outcome measures are required when using animal models for skeletal research.

Age Factors↗
PubMedDate not supplied

Open and arthroscopic patellar tenotomy for chronic patellar tendinopathy. A retrospective outcome study. Victorian Institute of Sport Tendon Study Group.

Chronic patellar tendinopathy often requires surgical treatment. We compared the outcomes in 25 subjects (29 tendons) who had had open patellar tenotomy and 23 subjects (25 tendons) who had had arthroscopic patellar tenotomy at a mean follow-up of 3.8 and 4.3 years, respectively. At follow-up, outcomes in the open and arthroscopic groups were as follows: 1) symptomatic benefit was seen in 81% of open and 96% of arthroscopic tenotomy patients, 2) sporting success was seen in 54% of open and 46% of arthroscopic tenotomy patients, 3) median time to return to preinjury level of activity was 10 months for open and 6 months for arthroscopic tenotomy patients, and 4) median Victorian Institute of Sport Assessment score at follow-up was 88 for open and 77 for arthroscopic tenotomy patients. There were no significant differences between groups for all outcomes. The appearance of the tendon on sonography remained abnormal in over 70% of subjects at follow-up, and sonographic appearance did not correlate with clinical outcome. Thus, arthroscopic patellar tenotomy was as successful as the traditional open procedure. Both procedures provided virtually all subjects with symptomatic benefit, but only about half the subjects who underwent either open or arthroscopic patellar tenotomy were competing at their former sporting level at follow-up.

Adolescent↗
PubMedDate not supplied

The incidence and distribution of stress fractures in competitive track and field athletes. A twelve-month prospective study.

The incidence and distribution of stress fractures were evaluated prospectively over 12 months in 53 female and 58 male competitive track and field athletes (age range, 17 to 26 years). Twenty athletes sustained 26 stress fractures for an overall incidence rate of 21.1%. The incidence was 0.70 for the number of stress fractures per 1000 hours of training. No differences were observed between male and female rates (P > 0.05). Twenty-six stress fractures composed 20% of the 130 musculoskeletal injuries sustained during the study. Although there was no difference in stress fracture incidence among athletes competing in different events (P > 0.05), sprints, hurdles, and jumps were associated with a significantly greater number of foot fractures; middle- and long-distance running were associated with a greater number of long bone and pelvic fractures (P < 0.05). Overall, the most common sites of bone injuries were the tibia with 12 injuries (46%), followed by the navicular with 4 injuries (15%), and the fibula with 3 injuries (12%). The high incidence of stress fractures in our study suggests that risk factors in track and field athletes should be identified.

Adolescent↗
PubMedDate not supplied

Risk factors for stress fractures in track and field athletes. A twelve-month prospective study.

The aim of this 12-month prospective study was to investigate risk factors for stress fractures in a cohort of 53 female and 58 male track and field athletes, aged 17 to 26 years. Total bone mineral content, regional bone density, and soft tissue composition were measured using dual-energy x-ray absorptiometry and anthropometric techniques. Menstrual characteristics, current dietary intake, and training were assessed using questionnaires. A clinical biomechanical assessment was performed by a physical therapist. The incidence of stress fractures during the study was 21.1% with most injuries located in the tibia. Of the risk factors evaluated, none was able to predict the occurrence of stress fractures in men. However, in female athletes, significant risk factors included lower bone density, a history of menstrual disturbance, less lean mass in the lower limb, a discrepancy in leg length, and a lower fat diet. Multiple logistic regression revealed that age of menarche and calf girth were the best independent predictors of stress fractures in women. This bivariate model correctly assigned 80% of the female athletes into their respective stress fracture or nonstress fracture groups. These results suggest that it may be possible to identify female athletes most at risk for this overuse bone injury.

Adolescent↗
PubMedDate not supplied

Risk factors for osteoporosis: A review.

Skeletal fragility and falls are the 2 most potent factors leading to osteoporotic fractures. The aim of this article is to review factors associated with women's risk of developing skeletal fragility and subsequent osteoporosis. Many factors have been implicated, but the evidence for some is unsubstantial. Low premenopausal bone mineral density (BMD), a decrease in BMD, and an increase in bone fragility -- which occur as a result of both aging and the menopause -- are major determinants of subsequent risk for osteoporotic fracture. In addition, low body mass index (BMI), low calcium intake, low physical activity, and smoking can affect BMD. The relative importance of the effects these physical and lifestyle factors have on BMD in midlife women is not fully established. The impact of gynecologic history (parity, lactation, oral contraceptive use, age of menarche) on BMD is uncertain.

Body Mass Index↗
PubMedDate not supplied

Risk factors for osteoporosis: prevalence, change, and association with bone density.

OBJECTIVES: To describe the prevalence of risk factors for osteoporosis in a population-based cohort of Australian-born midlife women; determine the effect of these risk factors on premenopausal and early perimenopausal bone mineral density (BMD); and describe changes in risk factors and any effect of these on bone loss. DESIGN: 4-year longitudinal community-based study. BMD of the lumbar spine (LS) and femoral neck (FN) was measured using dual x-ray absorptiometry (DXA). SETTING: Melbourne, Australia PARTICIPANTS: 224 Australian-born women aged 46-56 years MAIN OUTCOME MEASURES: Risk factors for osteoporosis, LS-BMD, FN-BMD, and change in risk factors and BMD. RESULTS: At baseline, 52% reported a calcium intake of less than 800 mg/day and 46% reported a caffeine intake of more than 360 mg/day; 29% exercised less than 1.5 hours/week; 5% had a body mass index (BMI) of less than 20; 14% were current smokers; 23% were past smokers; 10% reported abnormal menstrual histories; and 25% reported a family history of osteoporosis. BMD was positively associated with weight; BMI; and waist, hip, and trunk skin-fold measure (P less than .0005). At 4-year follow-up, there were increases in weight (P less than .0005), waist/hip ratio (P less than. 05), trunk skin-fold measurements (P less than.005), and calcium intake (P less than.05). In women who became late perimenopausal or postmenopausal, bone loss was associated with time in relation to the final menstrual period but not with other variables. CONCLUSIONS: There are multiple risk factors for osteoporosis in this Australian-born population of midlife women, but only anthropometric variables were associated with BMD at baseline. Significant changes during the menopausal transition in anthropometric variables and calcium intake were in the direction that could decrease the risk of osteoporosis but were not found to affect menopausal bone loss.

Body Mass Index↗