Biomedical subjects

J R Urbaniak

Publications and source records attributed to J R Urbaniak.

At least 19 recordsLinked to original sources

PubMed1992

Combined effect of acute denervation and ischemia on the microcirculation of skeletal muscle.

Using direct in vivo videomicroscopy and a fluorescein dye technique, reperfusion injury after 3 h of ischemia was studied in the acutely denervated cremaster muscle of the rat. Compared with normally innervated controls, ischemia-induced reperfusion injury was more severe in the denervated group and included a delay of blood flow recovery, vortex formation, edema, hemorrhage, and vessel spasm. Vessel size was reduced at the arteriole and small artery level, and there was a decrease of reactive hyperemia. The injury mechanism may be related to a loss of active vasomotion and vascular response to vasoactive substances after denervation. The results suggest that shortening the ischemia time of denervated tissues may reduce ischemia-induced reperfusion injury. Similarly, given the same ischemia time, improved tissue reperfusion may be expected if the nerve supply is maintained.

Animals↗

PubMed1992

The functional recovery of peripheral nerves following defined acute crush injuries.

This study evaluates the effect of crushing load on functional recovery of the sciatic nerve. Male Sprague-Dawley rats were divided into five groups: sham operation, resected sciatic nerve, and 100 g (13 mm Hg/mm2), 500 g (50 mm Hg/mm2), and 15,000 g (1,000 mm Hg/mm2) of sciatic crush load (groups 1-5). In groups 3-5, a 5-mm segment of sciatic nerve was crushed for 10 min using a specially designed crushing device. Motor functional recovery was assessed from hind-limb walking tracks by calculating a sciatic functional index. There was no detectable functional deficit in the group receiving sham operations, while the resected sciatic nerve group exhibited complete dysfunction for the full duration of the experiment. All groups subjected to crush exhibited an initial deficit that gradually recovered to normal by day 14 (100-g crush), day 39 (500-g crush), and day 53 (15,000-g crush). Histological changes were also related to the initial crushing load and the length of the recovery period. Results indicate that the crushing device described is able to administer an adjustable, defined crush injury to the rat sciatic nerve, and that the functional deficit resulting from such an injury can be easily monitored with a sciatic functional index. The rate of recovery of crushed nerves was directly related to the initial load. All crushed nerves recovered in this experiment, even after the application of a 15,000-g load for 10 min.

Animals↗

PubMed1992

Hemodynamic and histological differences in end-to-side anastomoses.

An end-to-side anastomosis is often a necessity in replantation surgery. This study examines the effects of elliptical versus slit arteriotomy and the angle of anastomosis on vessel patency and aneurysm formation. Forty male rats were divided into four groups of ten rats each. The right and left common iliac arteries were selected as a model. The results showed no significant statistical difference in patency rates among our four experimental groups. The end-to-side anastomotic technique of choice uses the elliptical arteriotomy placed at a 90 degrees angle. It provides good visualization and easy suture placement.

Anastomosis, Surgical↗

PubMed1992

Direct end-to-end repair of flexor pollicis longus tendon lacerations.

Between 1976 and 1986, 38 consecutive acute isolated flexor pollicis longus lacerations were repaired. This study excluded all replanted or mutilated digits and all lacerations with associated fracture. Average follow-up was 26 months. Tendon rehabilitation was standardized. Range of motion and pinch strength were measured postoperatively. Seventy-four percent (28/38) of the flexor pollicis longus injuries occurred in zone II. Neurovascular injury occurred in 82% of the lacerations, and this correlated with the zone of tendon injury. In 21% of the patients (8/38) both digital nerves and arteries were transected. Postoperative thumb interphalangeal motion averaged 35 degrees and key pinch strength was 81% that of the uninjured thumb. One rupture occurred in a child. Laceration of the flexor pollicis longus is likely to involve damage to neurovascular structures, and repair may be necessary. Direct end-to-end repairs within the pulley system do at least as well as delayed tendon reconstruction and do not require additional procedures.

Adolescent↗

PubMed1992

Reversing nerve-graft polarity in a rat model: the effect on function.

To evaluate the effect of nerve-graft polarity on function, a 1-cm segment of sciatic nerve was excised and reoriented in three groups of 20 adult Sprague-Dawley rats. In one group, the nerve was cut and anastomosed in the original orientation to act as a control. In the second group, the nerve-graft polarity was reversed 180 degrees. The final group underwent reversal of polarity 180 degrees and was rotated 180 degrees, (i.e., the posterior tibial nerve fascicles proximally were opposite to the peroneal nerve fascicles distally). Functional recovery was evaluated using Bain's modification of de Medinaceli's sciatic functional index (SFI). Rat-track analysis was performed over a 120-day period. Histologic correlation was also performed at the time of sacrifice. From our study, we concluded that reversing nerve-graft polarity, with or without rotation, does not influence subsequent function in this model.

Anastomosis, Surgical↗

PubMed1992

Anterior capsulotomy and continuous passive motion in the treatment of post-traumatic flexion contracture of the elbow. A prospective study.

Thirty-three patients who had a post-traumatic flexion contracture of the elbow were managed consecutively with anterior capsulotomy without tenotomy of the biceps tendon or myotomy of the brachialis muscle. The first fifteen patients (Group I) did not receive continuous passive motion postoperatively. Preoperative active extension for Group I was to an average of 48 degrees short of full extension, which improved to 19 degrees at a mean follow-up time of forty-five months. Subsequently, eighteen patients (Group II) received continuous passive motion postoperatively for a mean of six weeks. Preoperative active extension for Group II was to an average of 55 degrees short of full extension, which improved to 23 degrees at a mean duration of follow-up of thirty-five months. The mean preoperative arc of motion for Group I was 69 degrees, which improved to 94 degrees postoperatively. The mean preoperative arc of motion for Group II was 48 degrees, which improved to 95 degrees postoperatively. Five patients in Group I and six patients in Group II had severe preoperative heterotopic ossification. There was no correlation, however, between preoperative heterotopic ossification and the amount that extension of the elbow improved postoperatively. There was no postoperative increase in heterotopic ossification. Four patients in Group I and six patients in Group II had severe post-traumatic osteoarthrosis preoperatively. Anterior capsulotomy is an effective treatment of post-traumatic flexion contracture of the elbow. Although the postoperative use of continuous passive motion did not significantly improve mean active extension, it did improve active flexion and the total arc of motion.

Adolescent↗

PubMed1991

The effect of acute denervation on the microcirculation of skeletal muscle: rat cremaster model.

Although tissue is denervated during replantation of a severed part, tissue transfer, or muscle transplantation, there are few studies concerning the effects of acute denervation on muscle microcirculation. We have described a surgical procedure that totally denervates the rat cremaster muscle. Histological examination of the denervated tissue has given convincing evidence of nerve degeneration and skeletal muscle atrophy, accompanied by electrophysiological evidence of total denervation. The diameters of each component of the microcirculation were measured before and after denervation. Arterioles and arteries ranging in size from 10 to 70 microns in diameter were found to increase significantly in size immediately after acute denervation. Larger arteries and veins did not undergo significant diametrical increases. These findings suggest that total acute denervation significantly increases the diameter of small arteries and arterioles, thereby decreasing the resistance in the arterial bed and increasing blood flow. Since this phenomenon is of limited duration (20 min), it would appear to be ineffective in enhancing reperfusion and oxygenation at the time of reattachment of amputated parts or during vascularized tissue transfers, until methods of prolonging it for several hours or more are found.

Animals↗

PubMed1991

Inhibition of epinephrine-induced vasospasm with adrenoreceptor blockade in the rat cremaster muscle.

This study demonstrates that intravenous epinephrine causes arterial vasospasm, but not venous constriction, in the microcirculation of the rat cremaster muscle. This effect can be blocked by a smooth muscle relaxant such as papaverine or an alpha receptor antagonist such as phentolamine. Circulating vasospastic agents such as epinephrine are important determinants of microcirculatory blood flow, and inhibition by pharmacologic means may enhance blood flow and survival in microvascular surgery.

Animals↗

PubMed1991

Replantation in children.

The authors have replanted 162 parts in 120 children over the past 15 years. The youngest patient, undergoing successful replantation, was aged 7 months, 3 weeks. Unlike an adult, any child suffering a traumatic amputation should be considered for a possible replantation. Replantation should consist of minimal bone shortening to preserve epiphyseal plates, with repair of all severed structures. Longitudinal K-wires usually provide adequate fixation. Our survival rate for complete replantation in children under the age of 16 years is 77%. Long-term study showed that continued skeletal growth occurred and the digit attained 81% of normal longitudinal length at maturity. Recovery of sensibility in the replanted digit is nearly as good as for isolated digital nerve repair. Patient and parent satisfaction is high when replantation is successful, with uniform approval of the extensive effort required.

Bone Wires↗

PubMed1991

Morphologic and morphometric analyses of rat femoral arteries after crush injury.

Replantation after crush amputation has a relatively low success rate. An arterial crush injury was produced in rats under a range of pressure (8.5 to 2,551 g/mm2) and durations (10 to 60 minutes). The degrees of vessel injury and thrombus formation were evaluated as functions of both crush force and duration, and the healing process was followed for 8 weeks. Crushing resulted in morphologic damage to the arterial wall but did not impair patency. Damage was directly proportional to crush pressure and duration. Intimal denudation caused flat platelet adhesion but no thrombus formation or thrombosis. Re-endothelialization was completed by 2 weeks. Intimal hyperplasia appeared at 1 week and consisted of endothelia in the most luminal layers and smooth muscle in the deeper layers. the internal elastic lamina was intact in all specimens and was thought to minimize platelet aggregation on the arterial wall after denudation of the intima.

Animals↗

PubMed1991

Prosthetic silicone scaphoid strains: effects of intercarpal fusions.

To assess stress shielding by partial intercarpal fusion, strains within a silicon scaphoid prosthesis were measured in five fresh upper extremities while the wrist was moved through a functional range of motion before and after capitate-lunate and capitate-hamate-lunate-triquetral intercarpal fusions. Capitate-lunate fusions resulted in an overall 18.4% reduction in compressive strains and a 10.8% reduction in tensile strains. Capitate-hamate-lunate-triquetral fusions reduced compressive strains by 28.5% and tensile strains by 26.3%. Radially deviated positions and positions of extension produced no reduction in strains with the partial fusions. Modest strain shielding can be obtained with partial intercarpal fusions. The effect, however, is position dependent, and whether this degree of strain shielding can reduce the incidence of particulate synovitis remains unknown.

Arthrodesis↗

PubMed1991

Hematogenous patellar osteomyelitis associated with human immunodeficiency virus.

The case of a 37-year-old man with hematogenous osteomyelitis associated with the human immunodeficiency virus (HIV) is presented, with a review of the literature. Hematogenous osteomyelitis is a relatively rare entity in the patella; most cases have involved adolescents and immunocompromised patients. There have been no previous reports of hematogenous osteomyelitis in HIV-positive patients. The diagnosis requires clinical suspicion and roentgenographic evidence. Point tenderness over the patella and a painful, swollen knee joint are signs that should alert a physician to the possibility of hematogenous osteomyelitis. Laboratory studies are often of little value, and systemic symptoms are often absent. Treatment requires appropriately directed intravenous antibiotics and open drainage and curettage of the patella. Patellectomy may be required for large lesions and in instances of articular involvement. Computed tomography is a helpful diagnostic tool. The patient in this presentation had osteomyelitis of the patella with a knee pyarthrosis. He had open debridement of the extensor mechanism and knee joint, but ultimately required amputation because of repeat pyarthroses.

Adult↗

PubMed1990

Vasodilator action of prostaglandin E1 on microcirculation of rat cremaster muscle.

Vascular spasm is often present after microsurgical procedures, and its presence or absence can greatly influence the success rate of such operations. Prostaglandin E1 (PGE1) is known to be a potent vasodilator and antiaggregator of small blood vessels. Using intravital videomicroscopy in the rat cremaster model, this study visually and quantitatively monitored changes in vessel diameter to observe the effect of PGE1 on the microcirculation and compared its action with that of 1% lidocaine. The results suggest that PGE1 (10 micrograms/ml) can significantly relieve epinephrine-induced vasoconstriction at the terminal arteriole, arteriole, and small artery level (vessel diameters 10-50 microns). The vasodilatory action of PGE1 is reflected by an increase in vessel diameter, and PGE1 may have a role in reversing vascular spasm after microsurgery, enhancing the survival rate of replanted extremities.

Administration, Topical↗

PubMed1990

One hundred eleven thumb amputations: replantation vs revision.

One hundred eleven patients who sustained isolated, complete thumb amputation between 1971 and 1985 were reviewed to assess results of replantation and to compare these with results of amputation revision. Routine postoperative evaluation was performed in 69 successful replant patients and in 42 with revision. Twenty-five of the replant group and 18 of the revision group returned for additional testing that consisted of interview and physical examination, test of activities of daily living, Jebsen test of hand function, and both static and dynamic testing on the BTE work simulator. Ninety percent of replantations were between the metacarpophalangeal (MCP) joint and the proximal third of the distal phalanx. Shortening averaged 11 mm, and range of motion was 42% +/- 28% that of the uninjured thumb. One-half of the patients could touch the MP of their ring finger, and one-fourth could touch the proximal interphalangeal (PIP) joint. Twenty-one percent had 7 mm or less two-point discrimination, and 38% had between 8 and 20 mm. Eighty percent of both groups were able to perform activities of daily living at 80% of their uninjured side. Grip strength was approximately 84% of that of the uninjured hand in each group. Lateral pinch averaged 68% +/- 26% of that of the normal side in the replant group and 91% + 9% in the amputation group. Work simulator assessment of lateral and three-point pinch was better in the revision group. Scores on Jebsen testing were slightly better for those with replanted thumbs, but in general neither replant nor revision patients functioned as well as did Jebsen's normals.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗

PubMed1990

The relationship of functional return to varying methods of nerve repair.

This experimental study correlated varying methods of nerve repair with the degree of functional return using the rat sciatic nerve as a model. Six groups of adult male Sprague-Dawley rats (300 to 350 g) had their left sciatic nerve crushed (Group 1), transected and not repaired (Group 6), or transected and repaired using four methods that varied the degree of axonal alignment (Groups 2, 3, 4, and 5). Functional return was evaluated weekly using the sciatic functional index (SFI) and histology. Group 1 (crush) had a significantly better functional return than the other groups (p less than .001). Group 6 (no repair) had a significantly worse functional return than the other groups (p less than .001). Groups 2, 3, 4, and 5, regardless of the precision of axonal alignment, experienced the same degree of functional return (p less than .05). In all groups, with the exception of Group 1 (crush), the degree of functional return was poor. As multiple modifications in conventional microsurgical neurorrhaphy have not resulted in a significant functional improvement, factors not addressed by current techniques apparently compromise clinical results. Further improvement in the results of neurorrhaphy will require modifications in our techniques beyond presently conventional microsurgical methods.

Animals↗

PubMed1990

A comparative study of the effect of arterial and venous occlusion after various periods of ischemia.

The author attempted to quantify any additional tissue damage resulting from one hour of venous occlusion after controlled periods of ischemia in skeletal muscle, compared to equal time periods of ischemia. The rat quadriceps muscle was used. pH and temperature were monitored during the experiment and the damage was evaluated on histochemical sections. Of the other two parameters monitored in this study, the pH recovery rate during reperfusion best reflected tissue perfusion and served as a predictor for the extent of tissue damage, when global ischemia or the combination of ischemia and postischemic venous stasis did not exceed five hours. Apart from the nonstained lethally damaged areas, interstitial tissue edema and cellular infiltration were constant findings in all muscles that sustained ischemia or ischemia and subsequent venous occlusion. However, both findings were more pronounced in the muscles that underwent venous obstruction. Muscle fibers were more edematous after venous occlusion, compared to ischemic muscles. Thrombosed veins and collapsed arteries, surrounded by excessive edema and inflammatory reaction, were common in muscles after ischemia and venous occlusion. Comparing the difference in percent of lethal damage from one hour of postischemic venous stasis versus the damage from additional ischemia of equal duration, findings demonstrated comparable damage when reperfusion was established in less than five hours.

Animals↗

PubMed1990

Posterior labral tear as a block to reduction in an anterior hip dislocation.

The patient presented with an anterior dislocation of the hip that could not be centrically reduced by closed methods. Computed tomographic imaging after trial reduction revealed a posterior fragment that was limiting reduction. At the time of open reduction, a large posterior labral tear with a small avulsed posterior acetabular rim of bone was found to be blocking the reduction.

Adult↗

PubMed1990

Repair of isolated axillary nerve lesions after infraclavicular brachial plexus injuries: case reports.

Stretch injuries of the infraclavicular brachial plexus have a much better prognosis for spontaneous recovery than do their supraclavicular counterparts. We present three patients with stretch injuries of the infraclavicular brachial plexus who had spontaneous restoration of function in all muscles except the deltoid. Decreased shoulder abduction was a serious handicap to these individuals. At surgical exploration, each patient had an isolated, complete axillary nerve disruption at the quadrilateral space. Deltoid muscle function was restored in all three patients by repair of the axillary nerve with sural nerve grafts across the quadrilateral space.

Accidents↗