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Biomedical subjects

F Linde

Publications and source records attributed to F Linde.

At least 37 records · Page 2Linked to original sources
PubMed1989

The effect of constraint on the mechanical behaviour of trabecular bone specimens.

The effect of the boundary conditions between trabecular bone specimens and the test columns of the testing machine was studied together with the effect of side-constraint on the mechanical behaviour of trabecular bone during axial compression. Cylindrical specimens taken from the upper tibial epiphysis of autopsy knees were tested non-destructively by cyclic compression to 0.8% strain under different conditions. Fixation of the specimens to the test columns by a thin layer of bone cement increased the stiffness by 40% and reduced the energy dissipation to 67% of those measured under unconstrained conditions (p less than 0.001). The thin cement layer alone increased the stiffness 19% and reduced energy dissipation to 86% (n.s.). When the machine was equipped with polished steel columns coated by a film of low-viscous oil, both the stiffness and the energy dissipation were reduced to 93% of those measured under standard conditions (p less than 0.005). Trabecular bone specimens tested side-constrained by the surrounding trabecular bone (in situ) showed a 19% larger stiffness than that measured during later testing of the corresponding machined specimens (p less than 0.005) whereas the energy dissipation was not altered significantly. The same specimens showed a 22% increase of stiffness and a 68% increase of energy dissipation when they were side-constrained by a closely fitting steel cylinder (p less than 0.005).

Adult↗
PubMed1988

Femoral shaft fracture after hip arthroplasty.

Femoral shaft fractures after hip arthroplasties were treated in 74 noncemented hemiarthroplasties and 65 cemented arthroplasties. In loose prostheses the best clinical results and the least number of operations were achieved with revision arthroplasty with a long-stem prosthesis, combined with simple internal fixation methods when applicable. In firmly fixed prostheses the results of revision arthroplasty and traction treatment were similar. Cemented revision arthroplasty did not interfere with fracture union. Internal fixation with the prosthesis in situ cannot be recommended because of a large number of secondary revision arthroplasties and nonunions. Removal of the femoral stem prosthesis and internal fixation nearly always require a secondary revision and cannot be recommended.

Adult↗
PubMed1988

Socket loosening in arthroplasty for congenital dislocation of the hip.

Mechanical risk factors in loosening of the socket were radiographically analyzed in 123 Charnley arthroplasties performed during the period 1969-1982 for coxarthrosis secondary to congenital dislocation. The socket was placed as near the true acetabulum as possible without extensive soft-tissue release and without reinforcement of the acetabular roof by bone grafting. The rate of socket loosening was 19 percent using progression of a radiolucent line at the bone-cement interface to a width of greater than 1 mm as the criterion for loosening. Different predictors of loosening were analyzed by stepwise logistic regression analysis. Lack of lateral bony support for the socket was the prime predictor. The next most important predictors were the preoperative degree of hip dislocation and the position of the socket in relation to the true acetabulum.

Acetabulum↗
PubMed1988

Charnley arthroplasty in osteoarthritis secondary to congenital dislocation or subluxation of the hip.

A follow-up study was made on 129 consecutive Charnley arthroplasties in osteoarthritis secondary to congenital dislocation of the hip. The acetabular component was placed as far distal as possible using a standard technique. Bone grafting was not performed. The survival of the prostheses was assessed by the survivorship method. The cumulative survival rate of the prostheses was 93% after five years, 89% after ten years, and 80% after 15 years. In 77% of the cases the acetabular component had been placed in the true acetabulum or levels the rate of mechanical loosening of the acetabular levels the rate of mechanical loosening of the acetabular component (revisions and acetabular components showing a radiolucent line of increasing width) was 13% compared with 42% in the group where the acetabular component was placed proximal to the roof of the true acetabulum (p less than 0.005).

Adult↗
PubMed1987

Stiffness behaviour of trabecular bone specimens.

Trabecular bone specimens were tested by non-destructive technique with the purpose of investigating stiffness behaviour and optimizing stiffness determination. Cylindrical specimens (n = 25) were loaded repetitively (0.1 Hz, 30 cycles) by axial compression to 50% of predicted ultimate strength and finally compressed to failure. Analyses of single compression curves showed increasing stiffness (E') until a stress level about 50% of ultimate stress followed by decreasing stiffness. Curve fit analysis of the elastic part of the compression curve showed the best fit, when a second order polynomial was used (r = 0.94, p less than 0.001). The stiffness determined non-destructively at the 25% level of ultimate strength increased significantly to the tenth loading cycle followed by a steady state. The precision of stiffness determination as an average of five consecutive measurements at steady state was E' +/- less than 5% (95% confidence limits). A reproducibility test by repetition of the test sequence after 3 h rest showed qualitatively the same stiffness behaviour. The variation of stiffness determination between the two test sequences was +/- 27% at the first loading cycle falling to +/- 12% at steady state.

Bone and Bones↗
PubMed1987

Fixation of displaced femoral neck fractures. A comparison between sliding screw plate and four cancellous bone screws.

In a prospective, randomized trial, 104 consecutive patients with displaced femoral neck fractures were allocated either to fixation with a sliding screw plate or 4 ASIF cancellous bone screws. The patients were reexamined at fixed intervals to determine the time of union. The 2-year-cumulated rate of union was 64 per cent in the plate group and 84 per cent in the screw group.

Adult↗
PubMed1986

Avascular femoral head necrosis following fracture fixation.

A prospective, randomized trial of 104 consecutive patients with displaced fractures of the femoral neck treated with either a sliding screw plate or four AO cancellous bone screws was performed to study the influence of the fixation device and the fixation procedure on the vascularity of the femoral head. The vitality of the femoral head was determined by 99mTc-MDP scintigraphy performed 2-3 months after the operation. Eighty-seven patients (84 per cent) were available for assessment. The two treatment groups were comparable with regard to age, degree of primary displacement and quality of reduction. There were significantly more (P less than 0.01) avascular femoral heads or femoral heads with reduced vascularity in the sliding screw plate group (14/40, 35 per cent) than in the four AO cancellous bone screw group (5/47, 11 per cent).

Adult↗
PubMed1986

Injuries in orienteering.

In a one-year prospective study of 42 elite orienteers, 73 recent injuries (1.7 per runner per year) were found. Acute injuries totalled 52% and 48% were due to overuse. Ankle sprains made up 37% of acute injuries while the remaining were mainly contusions caused by falls or bumps against branches or rocks. Medial shin pain, Achilles peritendinitis, peroneal tenosynovitis and iliotibial band friction syndrome were the most frequent overuse injuries. All overuse injuries were located in the lower extremity while 18% of acute injuries was located elsewhere. Acute injuries were most frequent in the competitive season while overuse injuries occurred most often during the continuous training period.

Adult↗
PubMed1986

Early mobilizing treatment in lateral ankle sprains. Course and risk factors for chronic painful or function-limiting ankle.

In a prospective study, 150 patients with lesions of lateral ankle ligaments were treated with early mobilization without any fixation of the ankle. After 8 days, 67% were free from pain on ordinary walking and 81% had resumed work. After 1 month 90% were free from pain and 97% had resumed work. Sport was resumed by 70% of athletes after 1 month and 90% after 3 months. At the 1-year follow-up (n = 137), 18% were not fully recovered and experienced pain (14%) or functional instability (7%) or had not resumed sport at their normal level (7%). However, only 8% found the condition inconvenient. Athletes had an increased risk of residual symptoms (p less than 0.01) and residual symptoms occurred in 32% of top athletes after 1 year.

Adolescent↗
PubMed1985

Osteoarthritis of the hip in patients under 60 years of age. A study of the importance of pain at rest as an indication for intertrochanteric osteotomy.

Pain at rest with osteoarthritis of the hip may be due to increased intraosseous blood pressure, which falls immediately after an intertrochanteric osteotomy. Eighty-five consecutive hips from patients under 60 years of age at the time of operation were studied in order to evaluate if pain at rest was an indication for intertrochanteric osteotomy. Patients who operatively were predominantly in pain at rest had a significantly better prognosis than patients with a predominantly weight-bearing pain (P less than 0.05). Intertrochanteric osteotomy reduced pain for the group of patients with predominant pain at rest (n = 50) by 81%, 66%, and 56% at 5, 10, and 15 years respectively. In the group where weight-bearing pain was predominant (n = 35), the operation was a success in only 39% at 5 years and after.

Adult↗