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Biomedical subjects

L S Matthews

Publications and source records attributed to L S Matthews.

At least 73 records · Page 4Linked to original sources
PubMed1984

The thermal effects of skeletal fixation-pin insertion in bone.

In human-cadaver cortical bone, we measured the maximum temperatures and the durations of temperatures in excess of 55 degrees Celsius during experimental insertion of five types of external skeletal-immobilization pins. Drill speed, pin-point design, and predrilling were the variables examined. Drill speed was found to have an effect on the maximum temperature and the duration of temperatures in excess of 55 degrees Celsius only in the immediate vicinity of the hole. Pinpoint design was a more significant factor, and predrilling was highly effective as a method of minimizing temperature elevation.

Aged↗
PubMed1984

A counter rotating power drill for needle biopsy.

A new needle biopsy instrument and technique are described. The needle is powered and due to its scissor-like arrangement can provide a core of both soft and hard tissue, preserving histologic detail. The needle has been used in 25 patients, in all of whom an appropriate specimen was obtained.

Adolescent↗
PubMed1984

Hydrogen peroxide as a topical hemostatic agent.

Many research efforts have been directed toward enhancing the bone-cement interface of total joint arthroplasties. Hemostatic agents have been popularized as effective means of retarding the development of potentially harmful debris interposition adjacent to, and blood lamination patterns within, the methylmethacrylate. The hemostatic effectiveness of hydrogen peroxide was tested on six metaphyseal bone beds in ten mongrel dogs: three sites were treated with hydrogen peroxide and three were saline-treated control sites. The hemostatic effect of the treatments was determined by comparing blood loss per unit area per minute before and after application of the test solutions. The results indicate that hydrogen peroxide is an effective hemostatic agent and reduces the amount of blood and debris trapped within the trabecular bone methylmethacrylate interface.

Administration, Topical↗
PubMed1983

Fatigue failure of cortical bone screws.

An experimental study of the fatigue life of cortical bone screws under conditions which stimulated in vivo usage was performed. The two most important factors influencing fatigue life were axial screw tension (the force normal of the plate to bone) and the cyclic shearing load. All screws failed at the root of the thread in the interface between the plate and the bone. A modified screw design effectively resisted fatigue under the described experimental conditions.

Biomechanical Phenomena↗
PubMed1983

The mechanical properties of human tibial trabecular bone as a function of metaphyseal location.

Experimental determination of the elastic modulus and ultimate strength of human tibial trabecular bone as a function of metaphyseal location is presented. A 1 cm cubic matrix with planes parallel to the subchondral plate was defined on five fresh frozen cadaver tibias. Approximately 400, 7 mm X 10 mm cylindrical bone plugs were cut from the locations defined by the matrix and tested in uniaxial compressive stress at a strain rate of 0.1%S-1. Results of the study indicate that the trabecular bone properties vary as much as two orders of magnitude from one location to another. As might be predicted from Wolff's law, and noted by previous investigators, concentrations of strength arise from the medial and lateral metaphyseal cortices toward the major medial and lateral contact regions. These results may be valuable for improved analytical modeling and optimal prosthetic design.

Aged↗
PubMed1983

Clinical utility of knee arthrography.

We evaluated how information obtained from knee arthrography was used in clinical management by means of questionnaires answered by orthopedists both before and after arthrography. In 55 of the 76 patients, the abnormality was considered "moderately severe," and in two patients "insignificant" before arthrography. After arthrography, 30 were considered "moderately severe," and 22 were thought "insignificant." There was a similar diminution in the perceived need for surgery when the results of arthrography were known. Arthrography alters patient management in that a normal arthrogram in a clinically equivocal case seems to convince the orthopedist that the injury is not significant and that surgery is not necessary.

Humans↗
PubMed1982

The effect on supination-pronation of angular malalignment of fractures of both bones of the forearm.

UNLABELLED: Ten fresh human upper-extremity cadaver specimens were tested for the effect of residual angulation from simulated fractures of both bones of the forearm on the potential for range of rotation of the forearm and for limitations of pronation and supination specifically. Ten and 20-degree angulations for the radius and ulna, such as might be encountered in all reasonable clinical situations, were tested. Little significant loss of forearm rotation resulted from angulations of 10 degrees in any direction. With 20 degrees of angulation, there was statistically significant and functionally important loss of forearm rotation. CLINICAL RELEVANCE: A residual angulation of 10 degrees in mid-shaft fractures of the radius, ulna, or both bones of the forearm will not limit forearm rotation anatomically. Loss in the range of rotation can be expected with residual angeles of 20 degrees or more.

Forearm↗
PubMed1982

The wake-up technique as a dual protector of spinal cord function during spine fusion.

Intraoperative awakening is commonly used to evaluate voluntary motor function to lessen the risks of nerve damage during posterior spine fusion and Harrington rod instrumentation for idiopathic scoliosis. This is a report of intraoperative monitoring of tension in the soft tissues of patients with idiopathic scoliosis utilizing a strain-gauged distraction outrigger. The tension in soft tissues was found to drop following intraoperative awakening by an average of 52 N in the 14 patients monitored. The "wake-up" technique may aid in protecting the spinal cord from overdistraction by the increase in soft tissue tension present at the time of Harrington rod replacement in addition to providing a spot check of motor function. This increased tension may slightly repress curve correction.

Anesthesia, Inhalation↗
PubMed1981

Spherocentric arthroplasty of the knee. Clinical experience with an average four-year follow-up.

We studied eighty-two consecutive spherocentric total knee arthroplasties with an average follow-up of four years (range, two to six years). All patients had either severe preoperative instability or deformity, or both. The over-all functional improvement and symptomatic relief were excellent. Knees with preoperative instability did as well as those with preoperative deformity that were stable. The knees with preoperative valgus deformity were the most likely to have postoperative wound problems or transient nerve palsy, while those with preoperative varus deformity were much more likely to have loosening. Postoperative limb alignment of 7 to 9 degrees of valgus angulation protected against lucency and loosening. No new cases of lucency or loosening appeared after two and one-half years. The infection rate was 4 per cent and the rate of failure due to loosening was 5 per cent. The over-all reoperation rate was 9 per cent. Nine patients (with eleven arthroplasties) died during the follow-up period.

Aged↗
PubMed1977

The effect of biopsy-hole shape and size on bone strength.

Investigation in cadaver femora of the relationship between the shape or size of a hole made in the cortex and the breaking strength of the bone revealed that of the shapes studied, an oblong hole with rounded ends afforded the greatest residual strength. Furthermore, we found that increasing the width of the hole caused a significant reduction in strength, while increasing the length did not.

Biopsy↗
PubMed1977

The spherocentric knee: biomechanical testing and clinical trial.

The spherocentric knee is a non-hinged, intrinsically stable knee-joint prosthesis which allows controlled triaxial rotation and was designed specifically for use in severely deformed or grossly unstable knees. Biomechanical evaluation of the prosthesis implanted in fresh human cadaver limbs demonstrated highly favorable motion, stability, strength, deflection, and energy absorption characterists for the spherocentric prosthesis-bone assembly as compared with control cadaver knees. After an average follow-up of 25.5 months after the first twenty-five spherocentric arthroplasties, the clinical results were highly satisfactory and suggested that the spherocentric knee may be relatively resistant to the problems of wear debris, loosening, and breakage which have plagued other intrinsically stable knee-joint prostheses.

Aged↗
PubMed1976

A new technique for hemipelvectomy.

A new technique for hemipelvectomy has been developed in which a large anterior well vascularized flap is used. The preservation of an anterior flap is essential if the posterior flap cannot be preserved because of tumor involvement. The vascularized anterior flap may be superior to the posterior flap because of less dermal necrosis. Use of the anterior flap may increase the ease of hemipelvectomy and reduce blood loss at operation.

Adult↗