Improved preservation of skeletal muscle in amputated limbs using pulsatile hypothermic perfusion with University of Wisconsin solution. A preliminary study.

To determine whether pulsatile hypothermic perfusion with University of Wisconsin preservation solution is superior to topical cooling as a method for the preservation of amputated limbs, six pairs of amputated canine limbs were preserved for twelve to fifteen hours. One limb of each pair was subjected to topical cooling and the other, to pulsatile hypothermic perfusion with University of Wisconsin solution. The bioenergetic status of the limbs was monitored by 31phosphorus magnetic-resonance spectroscopy, and histological evaluation was performed to assess ischemic changes in the preserved tissue. The pH and tissue levels of adenosine triphosphate declined three times more slowly in the limbs that were preserved by pulsatile hypothermic perfusion than in the topically cooled limbs. Consistent with these findings, the perfused limbs also had less histological evidence of ischemic injury. The data from this in vitro study show that pulsatile hypothermic perfusion with University of Wisconsin solution, in combination with an optimum degree of topical cooling, is superior to topical cooling alone as a method of preserving the bioenergetic status of amputated limbs.

The serratus anterior free-muscle transplant for reconstruction of the injured hand: an analysis of the donor and recipient sites.

The present study evaluated donor-site function in eight patients for whom serratus anterior free-muscle transplantation was performed to treat a traumatic defect of the palm. The lowest two or three slips of the muscle were transferred from the uninjured side and covered with split-thickness skin grafts. After an average follow-up period of 50 months (range 13 to 84 months), function and appearance of the flaps were assessed, and shoulder strength on the donor side was objectively tested in six patients by using an isokinetic computerized robotic dynamometer. No patient noticed any change in upper extremity function following the procedure. Each of the three patients in whom three slips had been taken displayed mild scapular winging, but none complained of any related symptoms. Neither push strength nor abduction strength on the donor side was significantly different compared with that on the recipient side. The transplanted muscle provided excellent contour and durable cover in all eight hands with limited donor-site morbidity. For this reason, the serratus anterior transplant is our flap of choice for the treatment of large palmar defects.

Fetal fracture healing in a lamb model.

A large animal model to assess fetal fracture repair and the ability to close excisional bony defects is presented. Incisional and excisional ulnar fractures were made in 14 midgestation fetal lambs, harvested at serial time points, and subjected to high-resolution low-kilovolt magnification radiographs, magnetic resonance imaging scans, and histologic analysis. Fetal fracture healing was characterized by early closure of excisional defects and rapid fracture healing with minimal or no soft-tissue inflammation or callus formation. Magnetic resonance imaging scans of the fractures revealed a characteristic pattern compatible with the histologic findings, namely, minimal inflammation in soft tissue adjacent to the fracture site. Histologic and magnification radiographic findings indicated that complete bony repair occurred within 21 days in incisional defects and within 40 days in excisional defects. In both cases, healed fetal bone resembled normal bone matrix. Excisional defects, including periosteum, of greater than three times the width of the bony cortex closed rapidly with virtually normal-appearing bony matrix and with minimal or no callus formation.

Biomechanical analysis of a step-cut technique for flexor tendon repair.

We compared the strength of a new step-cut technique for flexor tendon repair with that of the widely used Kessler-Tajima technique, giving special attention to the relative contributions of the core and epitendinous sutures. 36 flexor digitorum profundus tendons from human cadavers were used. Corresponding digits from the same donor were paired, and the two tendons of each pair were placed in the Kessler-Tajima and step-cut groups, respectively. Each group had three subcategories of repair: (1) core repair alone; (2) epitendinous repair alone; and (3) full repair. In the Kessler-Tajima repair, the core stitch contributed more to ultimate tensile strength, while the epitendinous stitch contributed more to gap formation resistance. In the step-cut repair, however, the epitendinous stitch contributed more to both measures of strength. The full step-cut repair was 65% stronger in resisting gap formation and had 84% more ultimate tensile strength than the full Kessler-Tajima repair. We attribute the greater strength of the step-cut repair to the additional number of epitendinous loops, which lie perpendicular to the long axis of the tendon.

The Sauve-Kapandji procedure for the treatment of posttraumatic distal radioulnar joint problems.

The appropriate management of distal radioulnar joint (DRUJ) problems has no consensus. Although the Sauve-Kapandji procedure is not new, little has been written on the indications for its use. Our experience shows that this operation is an effective treatment for patients with some combination of posttraumatic DRUJ problems that involve arthritis, instability of the distal ulna, and ulna-plus variance.

Comparison of four objective methods of monitoring digital venous congestion.

This study sought to determine which of the four most commonly used objective monitoring modalities--pulse oximetry, laser Doppler flowmetry, skin surface temperature measurement, and skin surface fluorescence--is best able to detect early digital venous congestion. Digital venous congestion was induced in 12 hands by inflating a digital cuff to 5 mm Hg above the resting diastolic pressure. The cuff remained inflated for 1 hour while monitoring was done at 10-minute intervals. The baseline and experimental laser Doppler indices differed by at least 30% in each subject, and the laser Doppler index was always less than 40% during venous congestion. Skin surface fluorescence gave falsely normal results in three of eight hands, while pulse oximetry failed to detect venous congestion in any hand. The difference in temperature between the control and experimental fingers almost always exceeded the threshold of 2.5 degrees C. The results indicate that both laser Doppler flowmetry and skin surface temperature measurement are highly accurate methods of monitoring early digital venous congestion that are noninvasive and easy to use. Skin surface temperature measurement has further advantages in that thermometers are less expensive and easier to transport than laser Doppler devices. In contrast, skin surface fluorescence is invasive and cumbersome in addition to being less sensitive to experimentally induced early digital venous congestion than either laser Doppler flowmetry or skin surface temperature measurement. Pulse oximetry is unreliable in detecting early digital venous congestion.

The Allen's test: analysis of four methods.

Forty nonrandomly selected hands were studied with use of four types of Allen's test: (1) the digital systolic blood pressure method, (2) the subjective method, (3) the pulse oximeter method, and (4) the laser Doppler flowmetry method. The digital systolic blood pressure method, regarded as the standard, indicated abnormal pressure in three hands. Laser Doppler flowmetry gave the same results as those obtained by the digital systolic pressure method and, in addition, was easier to perform. Pulse oximetry falsely indicated adequacy of the collateral circulation in two of the three hands with abnormal digital systolic pressure. Eleven hands, including the three with abnormal digital systolic pressure, were abnormal according to the subjective method. The results of the present study indicate the following: (1) the laser Doppler Allen's test is accurate, quick, and easy to perform; (2) the pulse oximeter Allen's test should not be used because of potentially dangerous consequences to the patient in the event of a falsely normal result; and (3) the subjective Allen's test can be used as a quick screening test.

The effect of wearing a flexible wrist splint on carpal tunnel pressure during repetitive hand activity.

We investigated how repetitive hand activity normally affects carpal tunnel pressure and whether a flexible wrist splint can influence this effect. Nineteen healthy subjects were evaluated under four test conditions: at rest with and without a wrist splint (baseline) and while performing a repetitive task with and without a wrist splint. The task involved loading and unloading 1 lb. cans from a box at a rate of 20 cans per minute for period of 5 minutes. Carpal tunnel pressure and wrist angles were continuously monitored by means of a fluid-filled catheter inserted into the carpal canal and a two-channel electrogoniometer mounted on the dorsum of the hand and forearm. Without the splint, carpal tunnel pressure rose from a median baseline level of 8 +/- 6 mmHg to 18 +/- 13 mmHg during activity. With the splint, carpal tunnel pressure rose from a baseline of 13 +/- 5 mmHg to 21 +/- 12 mmHg during activity. Median carpal tunnel pressure during activity with the splint was no different from that without the splint. Our data indicate that the median nerve is subjected to increased pressure within the carpal tunnel during repetitive hand activity. Wearing a flexible wrist splint during activity limits the range of wrist motion but has no significant effect on carpal tunnel pressure.

An in utero model of craniosynostosis.

To define better the pathophysiology of craniosynostosis, we developed an in utero model in rabbits. Premature fusion of the sutures was achieved by osteoinduction using demineralized bone matrix (DBM). Thirty-six fetuses from 18 time-dated pregnant rabbits underwent coronal strip craniectomies and implantation of DBM at 25 days of gestation (term = 31 days). Seventeen (47%) survived vaginal delivery and 10 (28%) survived for long-term follow-up. Surviving, operated animals demonstrated bony fusion across the coronal sutures presumably due to osteoinduction by the DBM. Coronal computed tomographic scans with sagittal reconstructions revealed that experimental animals had taller and wider skulls than nonoperated control animals. We conclude that employing DBM to create craniosynostosis in the fetal rabbit is technically feasible. Such a model may be used to more clearly define the pathophysiology of craniosynostosis and to evaluate methods of treatment.