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Biomedical subjects

A H Burstein

Publications and source records attributed to A H Burstein.

At least 19 recordsLinked to original sources
PubMed1992

Custom total shoulder arthroplasty in inflammatory arthritis. Preliminary results.

Twenty-three patients with inflammatory arthritis and rotator cuff deficiency have undergone 27 custom-fit total shoulder arthroplasties. The design used included a short-stem humeral component and a metal-backed glenoid component with an offset keel. The glenoid component was custom-fit to provide maximum coverage of the glenoid surface. The average age of the patients at the time of surgery was 55 years (range, 20-75 years). All patients had inflammatory arthritis, 16 were on steroids, and all had some degree of rotator cuff involvement ranging from small to complete tears. The average length of follow-up study was 5 years (range, 3-7 years). The average preoperative shoulder score was 36 points (range, 15-50 points) with an average pain score of 7 (of 30) points. Postoperatively, the shoulder score improved to 85 points with a pain score of 28 points. Twenty-one shoulders scored a good to excellent result. Two patients required reoperation, both for recurrent rotator cuff tears, one of which occurred after a fall. Radiographic analysis revealed no incidence of humeral radiolucency and six cases of glenoid radiolucency. Only two of these were progressive and both were associated with irreparable rotator cuff tears. Thus, in the early follow-up, this design of glenoid has decreased the incidence of glenoid radiolucency in this difficult patient population.

Adult↗
PubMed1991

Telemeterized in vivo hip joint force data: a report on two patients after total hip surgery.

Two telemeterized femoral components were implanted in two patients as part of normal total hip replacement procedures. The two components were instrumented to measure the three force components directed along: (a) the neck axis, (b) transverse to the neck axis and in the plane of the prosthesis, and (c) transverse to the neck axis and perpendicular to the plane of the prosthesis. Data were collected at multiple sessions during the early postoperative period for a number of standard activities, including gait, stair climbing, rising from a chair, single leg stance, double leg stance, ipsilateral and contralateral straight leg lifts while supine, ipsilateral flexion and extension while standing, and ipsilateral abduction while standing and lying on the contralateral side. These data are summarized and compared with the published results from analytic studies and with the results from previous studies using instrumented femoral components. Peak loads for gait during the period of study were roughly 2.7 body weights (BW) when the patients walked at their normal pace. Contact forces at the hip during stationary single leg stance approximated the peak loads during gait with values ranging from 2.1 to 2.8 BW. The highest forces recorded reached values approaching 5.5 BW and occurred during periods of instability while the patient engaged in stationary single leg stance. Our in vivo data indicate that forces generated during the above activities increase in magnitude quite rapidly during the early postoperative period and that during this period the patients have the ability to perform the activities of daily living without generating the high amplitude joint contact forces suggested by the results of dynamic studies. Joint contact forces during gait were found to depend on speed, but the high absolute magnitudes predicted by model studies were not supported by the in vivo data.

Aged↗
PubMed1989

Prevention of ligament and meniscus atrophy by active joint motion in a non-weight-bearing model.

This study describes the effect of active joint motion on the maintenance of ligament and meniscus mass in a non-weight-bearing model of disuse. Denervation and fixation models of immobilization have shown that resorption of isotope and atrophy of mass occurred for hard tissue (bone) and soft tissues (ligament, tendon, or meniscus). A unilateral ankle disarticulation model of disuse that maintains active knee motion without weight bearing was studied for 8 weeks in dogs that were chronically prelabeled with three different isotopes. The effects of non-weight-bearing without denervation or fixation were analyzed for the resorption of isotopes, and net atrophy of bone mass (femur or tibia) and soft-tissue mass (collateral or cruciate ligaments, menisci). A large and similar loss of all three isotopes, as well as collagen and calcium mass occurred for whole femur and tibia; this indicated that mass loss was equivalent to bone resorption and suggests little replacement with new bone. No loss of isotope or mass per whole tissue occurred for the collateral and cruciate ligaments or menisci. The strength of the femur-anterior cruciate ligament-tibia complex was analyzed by a tensile failure test when a fast rate of deformation was applied; the results did not differ qualitatively or quantitatively between control and experimental limbs. The absence of weight bearing for 8 weeks resulted in marked bone atrophy without resorption or atrophy of soft tissues, or decrease of the mechanical strength for the femur-ligament-tibia complex.

Animals↗
PubMed1988

Telemetric force measurements across the hip after total arthroplasty.

A telemeterized total hip prosthesis was implanted in one patient and force-data were obtained. Thirty-one days postoperatively, the magnitude of the joint-contact force during double-limb stance was 1.0 times body weight. During ipsilateral single-limb stance the joint-contact force was 2.1 times body weight, and during the stance phase of gait the peak force typically was 2.6 to 2.8 times body weight, with the resultant force located on the anterosuperior portion of the ball. During stair-climbing, the force was 2.6 times body weight. At peak loads, the angle between the resultant force and the axis of the neck was 30 to 35 degrees and that between the resultant force and the plane of the prosthesis was 20 degrees. During stair-climbing or straight-leg raising, the out-of-plane orientation of the resultant force increased substantially. These data provide information concerning the forces that must be sustained by prosthetic hip joints during a number of common activities of daily living within the first month after implantation. The results also provide insight into the progression of early recovery and demonstrate the variety of forces that are generated during this period.

Aged↗
PubMed1986

A clinical and radiographic analysis of loosening of total knee arthroplasty components using a bilateral model.

Patients undergoing bilateral, simultaneous total knee replacement provide a unique opportunity to study the role of operative techniques in the development of radiolucent lines because variables such as age, sex, weight, diagnosis, and bone quality are internally matched when the result on one side is compared with that of the other. This allows more conclusive examination of operative factors, such as component alignment, level of tibial bone resection, and cement handling. With this as the objective, the clinical and radiographic results of the first 50 bilateral total knee replacements performed by the senior author were studied. Postoperative alignment was found to influence significantly the incidence of tibial radiolucent lines. Use of cement to reconstruct defects in the proximal tibia resulting from preoperative deformity consistently led to the development of radiolucent lines in the area of the defect. There was also indirect evidence that failure to achieve an intimate microinterlock at the bone-cement interface may play a major role in the development of tibial radiolucent lines.

Adult↗
PubMed1986

The contributions of dietary protein and mineral to the healing of experimental fractures. A biomechanical study.

We examined the contributions of dietary protein and mineral to fracture-healing by assessing the mechanical properties of fracture callus in rats that were fed a diet that was deficient in or enriched by these nutrients. In order to isolate the effects of diet on fracture-healing, we developed a method for producing a standard closed femoral fracture with minimum-soft-tissue injury. Three groups of animals were studied. Group I was a control group, in which the rats did not undergo an operation. The rats in Group II underwent intramedullary pinning of the right femur, but no fracture was created. The rats in Group III underwent pinning identical to that used for Group II, after which a closed, transverse femoral fracture was produced. Immediately after surgery, the animals in each group were subdivided into five diet-treatment subgroups. Subgroup A received a regular diet; Subgroup B received a protein-free diet; and Subgroup C received a mineral-free diet that was lacking in calcium, phosphorus, and vitamin D. Subgroup D received a protein-supplemented diet that was composed of three times the calculated requirement of protein, and Subgroup E received a mineral-supplemented diet that was composed of three times the calculated requirements of calcium and phosphorus as well as a therapeutic dose of vitamin D, equivalent to that used in the treatment of osteomalacia. At the end of five weeks, the animals were killed and the right femur of each one was subjected to torsion-testing to failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

The effect of conformity and plastic thickness on contact stresses in metal-backed plastic implants.

Surface damage in polyethylene components for total joint replacement is associated with large contact stresses. An elasticity solution and finite element analyses were used to determine the influence of design parameters on the stresses due to contact in metal-backed components. For nearly conforming contact surfaces, it was found that the stresses in the plastic are very sensitive to clearance, that minimum plastic thickness of 4-6 mm should be maintained for metal-backed components, and that bonding the plastic to the metal backing reduces tensile stresses in the plastic at the edge of the contact zone.

Elasticity↗
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↗