Search PubMed⌕ Search

Biomedical subjects

A H Burstein

Publications and source records attributed to A H Burstein.

At least 73 records · Page 4Linked to original sources
PubMed1981

Structural properties of immature canine bone.

Structural properties of growing canine long bones were determined from three and four-point bending tests. Mechanical and geometric properties were found to follow a biphasic growth process, with a rapid increase in bending strength and moment of inertia from l to 24 wk of age and a substantially decreased rate thereafter to maturity. Predicted bone tissue material properties were also found to follow this biphasic developmental process.

Age Factors↗
PubMed1980

Biomechanical analysis of the sliding characteristics of compression hip screws.

UNLABELLED: We examined the effect of screw-plate angle on the sliding characteristics and jamming potential of four popularly used stainless-steel and cobalt-chromium-molybdenum compression hip screws. The actual coefficient of sliding friction for these alloys was measured in each device. The force on the screw required to overcome the static frictional force also was determined, by varying the lengths of screw engaged in the barrel under conditions of static equilibrium representing 130-degree and 150-degree screw-plate angles. For the 130-degree loading configuration, this force was significantly (p < 0.001) higher than that required for the 150-degree loading configuration for all four screw types. The actual coefficient of friction was relatively constant for each material, although slight variations due to differences in design between screw types were found. A positive correlation (p < 0.01) was seen between the apparent coefficient of friction (the ratio of sliding force to normal force) and the length of the screw extending from the barrel. All stainless-steel screws jammed in the 130-degree tests when not completely engaged in the barrel. None of the 150-degree tests produced jamming and none of the cobalt-chromium-molybdenum screws jammed in either the 130-degree or the 150-degree test. Examination of jammed devices by scanning electron microscopy showed galling on the superior surface of both the screw and the barrel. CLINICAL RELEVANCE: Understanding the conditions that facilitate sliding of hip screws aids in ensuring their proper use. The higher the nail-plate angle, the easier it is to impact the hip-fixation device and thus allow bone impaction and stability at the fracture site. The potential for jamming a sliding hip screw is decreased by maximum engagement of the screw in the barrel. Differences in the material and design of sliding hip-fixation devices have relatively little effect on the sliding characteristics compared with the nail-plate angle and the engagement of the screw in the barrel.

Alloys↗
PubMed1979

A fluted intramedullary rod for subtrochanteric fractures.

A new intramedullary rod has been developed for the treatment of subtrochanteric fractures. The stepped fluted rod is designed as a single unit and has exceptional bending strength and rigidity as well as excellent torsional load-carrying capacity. It has been used successfully in eighteen patients with a variety of subtrochanteric fractures. Union was achieved in all instances and no failure of the implant occurred. The simplified technique of insertion, the strength of the device, and the results of this study indicate that the fluted subtrochanteric rod has several advantages over other available devices.

Adult↗
PubMed1979

Proximal "tube" realignment of the patella for chondromalacia patellae.

In young people complaining of patellar pain there is often an anatomic basis (an increased quadriceps angle or a high-riding patella). Forty-eight knees with one or other of these abnormalities underwent proximal quadriceps realignment. The results were excellent or good in 94%. Shaving of chondromalacic cartilage was also done in 11 knees but did not seem to improve the results, and is not now recommended except for "blister" lesions. Extensor mechanism dysplasia is an etiologically correct name for the disorder and therefore preferable to "chondromalacia patellae."

Cartilage Diseases↗
PubMed1978

A fluted femoral intramedullary rod. Biomechanical analysis and preliminary clinical results.

An intramedullary rod for the femur was designed and compared with rods commonly used. Its bending strength was increased 40 to 80 per cent and its torsional rigidity was increased 230 to 3,000 per cent compared with the other devices tested. In forty patients with traumatic and pathological fractures and osteotomies of the femur, excellent fixation was achieved and very early weight-bearing was possible. In all fresh fractures and non-infected non-unions, union occurred very promptly and bone-grafting was not required in most instances. The stregth and rigidity of the device made it exceptionally useful for non-unions, pathological fractures of the femur, and resection-fusions of the knee.

Adolescent↗
PubMed1976

The mechanical properties of prematurely and non--prematurely ruptured membranes. Methods and preliminary results.

The mechanical properties of the chorioamniotic membranes have been studied by several investigators over the past 100 years. No relationship between membrane strength, as measured by rupture tension, and premature or non-premature rupture of the membranes has been demonstrable. In the present study, several measures of the mechanical properties of the chorioamniotic membranes were examined. These included thickness, rupture tension, work to rupture, strain to rupture, and moduli of elasticity (Young). Prematurely and non-prematurely ruptured membranes differed with respect to thickness near the rupture site and Young's modulus near the placenta. Differences between the groups for the other parameters were not significant. This study suggests that there may be inherent differences between membranes which rupture prematurely and those which do not.

Biomechanical Phenomena↗
PubMed1976

The biomechanical analysis of bone strength: a method and its application to platycnemia.

Traditional methods of bone analysis (both metric and topographic) are restricted to external characters. Special distribution of material is, however, equally critical to an understanding of a bone's function. Dynamic testing to determine whole bone strength can only be performed on fresh specimens. Methods for the calculation of both bending and torsional strength of other specimens (such as preserved or fossil bones) are developed in this paper. In order to illustrate the methods, the functional significance of tibial shaft cross sectional variation is investigated.

Biomechanical Phenomena↗
PubMed1976

Aging of bone tissue: mechanical properties.

The mechanical properties of machined cortical bone specimens from human femora and tibiae were determined in tension, torsion, and compression for a population ranging in age from twenty-one to eighty-six years. No significant differences were found between the mechanical properties of male and female specimens. Tibial specimens had greater ultimate strength, stiffness, and ultimate strain than femoral specimens. Consistent decreases with age for all mechanical properties except plastic modulus were found in the femoral but not in the tibial specimens. No consistent significant differences in tension properties were found in specimens from normal, osteoporotic, and corticosteroid-treated individuals.

Adult↗