PubMed Health⌕ Search

Biomedical subjects

W C Allen

Publications and source records attributed to W C Allen.

33 records · Page 2Linked to original sources
PubMedDate not supplied

The effects of chlorhexidine irrigation solution on contaminated bone-tendon allografts.

The purpose of this study was to determine an expedient and effective method for disinfecting contaminated human bone-tendon allografts. The first part of this study used beef muscle and cadaveric human tissues to determine the most effective solution and volume to decontaminate tissues inoculated with four different organisms: Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Of the solutions tested (benzalkonium chloride, castile soap, castile soap followed by benzalkonium chloride, triple antibiotic, chlorhexidine gluconate, and chlorhexidine gluconate/triple antibiotic), only the 4% chlorhexidine power irrigation solution and 4% chlorhexidine/triple antibiotic bath completely disinfected all tissues. Work in part 2 revealed that a 2% chlorhexidine irrigation solution was equally effective as the 4% solutions. Part 3 of the study involved human Achilles tendon-calcaneus allografts. We found similar results: 3 liters of 2% chlorhexidine power irrigation solution thoroughly removed all microorganisms from the contaminated tissues. All control allografts irrigated with normal saline solution alone revealed positive bacterial growth for all four organisms after 72 hours' growth on sheep blood agar. Total decontamination time was 10 to 12 minutes. Two percent chlorhexidine irrigation solution may be an effective method for decontaminating human bone-tendon allografts challenged with a polymicrobial inoculum. This method of disinfecting bone-tendon allografts is at least five times more expeditious than methods in previously reported studies.

Animals↗
PubMedDate not supplied

The throw: biomechanics and acute injury.

The throw and its modifications are integral components of many sports. This study correlates case histories of acute injuries in throwing with a biomechanical analysis of the throwing mechanism. Comparisons are made with a similar analysis of the kick analyzed by the same film technique and computer program. Just prior to ball release, the pitching arm extends through an arc of about 73 degress in 40 msec, beginning with the elbow flexed at 80 degrees. This produces an axial load on the humerus and coincides with a pulse of external torque at the shoulder. This acts as stress protection to the humerus which is developing an internal torque of 14,000 inch-lb prior to ball release. The change in angular velocity, or the angular acceleration, during the throw is acquired in a much shorter time than in the kick. Torque is directly proportional to angular acceleration. This necessitates the development of substantially higher torques in the humerus during the throw than about the knee during a kick. The kinetic energy in the arm is 27,000 inch-lb during the throw. This is much higher than the kinetic energy in the kicking leg because the kinetic energy varies proportionally with the square of the angular velocity of the extremity. The angular velocity of the arm is about twice that of the leg. Thus, the pitching arm contains about four times as much kinetic energy as the kicking leg. These severe overloading conditions predispose the upper extremity to injury in the throwing mechanism.

Adolescent↗
PubMedDate not supplied

Biomechanics of the spine in the polevaulter as related to spondylolysis.

An athlete was filmed at high speed to anatomically plot the position of the vertebrae during several pole vaults. A computer analysis adapted from a previously described program (Gainor, BJ, et al: The kick: Biomechanics and collision injury. Am J Sports Med 6: 185-193, 1978) was used to quantify the kinematic data. The thoracic and lumbar vertebrae of the polevaulter began in a neutral position but rapidly hyperextended 40 degrees during pole plant. The spine subsequently flexed 130 degrees in 0.65 seconds as the pole uncoiled and the athlete was propelled towards the bar. Angular velocities of the spine reached a maximum of 6 radians/sec during both extension and flexion. More significantly, angular accelerations of 150 radians/sec2 occurred in hyperextension, and 180 radians/sec2 in hyperflexion. Torque about the spine was estimated to be 1,500 inch-pounds during extension and 1,800 inch-pounds during flexion. The maximum kinetic energy in the athlete's body was calculated to be 36,000 inch-pounds. We believe the magnitude of these torques and accelerations predispose the back to injury. These results were correlated with several cases of spondylolysis in competing polevaulters.

Adolescent↗
PubMedDate not supplied

The snapping hip syndrome.

The snapping hip syndrome is a symptom complex characterized by hip pain and an audible snapping of the hip with exercise typically seen in young individuals. "External" and "internal" etiologies have been described, although the "internal" etiology is poorly understood. A clinical, radiographic, and anatomical study of eight patients with this disorder, secondary to an internal etiology, was undertaken to aid in the diagnosis and surgical treatment. Iliopsoas bursography with cineradiography revealed subluxation of the iliopsoas tendon to be an apparent cause of the snapping hip. The anatomy of the hip in relationship to the iliopsoas tendon is defined with the anterior inferior iliac spine, iliopectineal eminence, and lesser trochanter assuming a significant role in the syndrome. An operative approach involving a partial release and lengthening of the iliopsoas tendon, with minimal resection of a lesser trochanteric bony ridge, if involved, is described.

Adult↗
PubMedDate not supplied

Surgical correction of the snapping iliopsoas tendon.

Eighteen patients with 20 symptomatic hips underwent lengthening of the iliopsoas tendon for persistent painful snapping of this "internal" variety of snapping hip. We referred to the pathologic, painful snapping of the iliopsoas in the deep anterior groin as the "internal" snapping hip. This is in contrast to the more common and better-known "external" snapping that involves the greater trochanter and its overlying soft tissues. The results of our iliopsoas lengthening procedure are presented here. Lengthening of the iliopsoas tendon was accomplished by step cutting of the tendinous portion of the iliopsoas. The pathoanatomy of this poorly understood symptom complex was described in 1984 paper from this institution and is reviewed here. Iliopsoas bursography demonstrated a sudden jerking movement of the iliopsoas tendon between the anterior inferior iliac spine and iliopectineal eminence, synchronous with the patient's pain and often accompanied by an audible snap. The average preoperative duration of symptoms was 2.9 years, and the average length of postoperative followup was 25 months. All patients, except one, had a marked reduction in the frequency of snapping after tendon lengthening, and 14 of 20 hips had no snapping postoperatively. Of the six patients who had recurrence of snapping, all but one stated that this occurred much less frequently and was much less painful compared to the preoperative state. Two hips required reoperation. Postoperatively, only three patients complained of subjective weakness, and most patients were unlimited in physical activity with return to activities such as competitive football, pole vaulting, and long-distance running.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗