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Biomedical subjects

V R Hentz

Publications and source records attributed to V R Hentz.

At least 19 recordsLinked to original sources
PubMed1996

Vascularized toe joint transfer to the hand.

From 1984 to 1993, 36 vascularized toe joints were transferred in 33 patients. The present study group excludes 3 toe joint transfers to elbow and temporomandibular joints and 4 toe joint to hand transfers lost to follow-up. The final study group includes 29 vascularized toe joint transfers in 27 patients, 21 males and 6 females. All were performed for posttraumatic reconstruction, except one transfer for congenital deformity. Follow-up averaged 32.4 months. Mean range of motion was 34 degrees in toe metatarsophalangeal joint to hand metacarpophalangeal joint transfers, 32 degrees in toe proximal interphalangeal joint to hand metacarpophalangeal joint transfers, and 24 degrees in toe proximal interphalangeal joint to hand proximal interphalangeal joint transfers. Although vascularized toe joint transfer is an alternative to arthrodesis, in order to have a greater range of motion than average, the patient must have well-functioning muscle and associated tendons effecting joint motion. Good results were obtained in two immediate free vascularized toe joint transfers to complex injuries involving loss of the metacarpophalangeal joint. We encourage toe joint transfer in selected complex hand injuries.

Adolescent↗
PubMed1995

Short gracilis myocutaneous flaps for vulvoperineal and inguinal reconstruction.

From October of 1990 to April of 1993, 16 short gracilis myocutaneous flaps and 1 short gracilis muscular flap were used to reconstruct vulvoperineal, inguinal, perineal, and ischial soft-tissue defects. Five of the 6 bilateral myocutaneous flaps were used for vulvoperineal reconstruction after radical vulvectomy combined with partial vaginectomy and one radical vulvectomy. Four unilateral myocutaneous flaps and one muscular flap were used for inguinal, suprapubic, ischial, and perineal reconstruction after release of contracted scar or excision of an ischial pressure sore. The immediate complications consisted of partial necrosis of the distal third of the cutaneous tissue in 6 patients, 1 superficial cutaneous necrosis, and superficial wound infection in 7 patients. The muscular portion of the flaps all survived. The follow-up period was from 6 to 27 months. The short gracilis flap has greater mobility than the classically described gracilis flap. On the basis of the functional and cosmetic results, the short gracilis flap is an excellent alternative to the more bulky classic gracilis flap.

Adolescent↗
PubMed1995

Action potentials of curved nerves in finite limbs.

Previous simulations of volume-conducted nerve-fiber action-potentials have modeled the limb as semi-infinite or circularly cylindrical, and the fibers as straight lines parallel to the limb surface. The geometry of actual nerves and limbs, however, can be considerably more complicated. This paper presents a general method for computing the potentials of fibers with arbitrary paths in arbitrary finite limbs. It involves computing the propagating point-source response (PPSR), which is the potential arising from a single point source (dipole or tripole) travelling along the fiber. The PPSR can be applied to fibers of different conduction velocities by simple dilation or compression. The method is illustrated for oblique and spiralling nerve fibers. Potentials from oblique fibers are shown to be different for orthodromic and antidromic propagation. Such results show that the straight-line models are not always adequate for nerves with anatomical amounts of curvature.

Action Potentials↗
PubMed1993

The nerve gap dilemma: a comparison of nerves repaired end to end under tension with nerve grafts in a primate model.

The objective of this study was to compare, in a clinically relevant primate model, axon regeneration after epineurial repair under tension (15 mm gap) with interfascicular nerve grafts with the use of either standard microsuture techniques or a new interfascicular nerve graft technique termed fascicular tubulization that uses a hypoantigenic collagen membrane formed into a tube to approximate nerve ends. Electrophysiologic analysis demonstrated that the percentage of proximal axons that conducted across the repair site was greater in those nerves repaired under tension with epineurially placed sutures than in either of the tensionless repairs involving interfascicular graft techniques. The mean diameters of the regenerated axons repaired under tension with epineurial sutures were greater than those of the nerves repaired with interfascicular grafts, although the difference was not statistically significant. Interfascicular nerve grafting with tubulization using the current collagen tube resulted in regeneration equal to the sutured interfascicular nerve grafts. For modest defects (perhaps up to 3 to 4 cm in the adult), it seems advantageous to accept the modest tension associated with an epineurial repair rather than to use an autograft (or artificial graft) to achieve a tension-free repair.

Anastomosis, Surgical↗
PubMed1993

Extensor digiti minimi tendon transfer to prevent recurrent ulnar drift.

Thirty percent of patients with rheumatoid arthritis develop ulnar drift. Although numerous operations have been described, recurrence of the deformity is frequent. We recommend use of the extensor digiti minimi tendon transfer to prevent recurrent ulnar deviation. The tendon insertion is moved from a dorsal location to a dorsal-radial position. In this new location, the tendon produces both extension and radial deviation. Moreover, this transfer is maximally effective in extension when ulnar drift is greatest. We have used this transfer 28 times during the past 6 years. In evaluating patients more than 1 year after surgery, metacarpal phalangeal joint extension averaged 52 degrees and there was no evidence of recurrent ulnar drift of the little finger. The only problem was slight hyperextension of less than 5 degrees in approximately half of the patients. However, in no patient was this functionally a problem. We recommend the use of this tendon transfer in all patients with ulnar drift undergoing metacarpal phalangeal joint replacement for rheumatoid arthritis.

Arthritis, Rheumatoid↗
PubMed1992

The pulp plasty: a composite graft for complete syndactyly fingertip separations.

Composite grafts of skin and subcutaneous fat harvested from the glabrous non-weight-bearing areas of the foot were used to graft 34 fingertips after separation of 23 complete syndactyly webs in 13 patients. Simple complete syndactylies accounted for 17% and complex complete syndactylies accounted for 83%; synonychia was encountered in 70%. Follow-up averaged 13.9 months (minimum, 2 months, maximum 33 months). All patients had 100% take of the composite graft. Subjective gradings were 94% good, 6% fair, and there were no poor results. This technique provides a relatively normal contour and satisfactory pad to the fingertip.

Adipose Tissue↗
PubMed1992

Efficacy of immobilization following aspiration of carpal and digital ganglions.

In a prospective study 69 carpal and digital ganglions were aspirated, multiply punctured, and digitally ruptured. Fifty percent of the wrists and digits were immobilized for 3 weeks and 50% were mobilized early. Follow-up was 1 year. Immobilization in our study did not significantly improve the results of treatment. During the course of the study, 51% of all ganglions did not recur. The outcome was successful in 52% of the wrists and digits that were immobilized and in 50% of those that were not. Forty-six percent of the dorsal carpal ganglions did not recur. Treatment was successful in 48% of dorsal carpal ganglions in which the wrists were immobilized and in 45% of those that were not. Similar percentages were found for palmar and digital ganglions. From our results, we conclude that immobilization does not significantly improve the successful treatment of ganglions over perforation and aspiration alone.

California↗
PubMed1991

Brachial plexus microsurgery in children.

From this review, the following points have emerged: 1. The typical obstetrical palsy is a traumatic lesion caused by forced lowering of the shoulder during delivery. 2. While the lesion may affect all the roots, the upper roots are usually ruptured, whereas the lower roots (if involved) are always avulsed. 3. Spontaneous recovery is possible, but its quality depends on how early recovery of previously paralyzed muscles begins. If the biceps have not started to recover by 3 months, the final result will be poor. It is at this time interval that a surgical decision should be made. 4. Surgical repair is always possible, usually by grafting, though repair can be difficult if significant numbers of avulsions have occurred. 5. The results of surgical reconstruction are better than are the results of spontaneous evolution, at least in those patients who reach the age of 3 months without evidence of recovery of the biceps. For example, more than half of the patients recover a nearly normal shoulder after grafting C5, C6 lesions in Gilbert's series, whereas in the same control population of patients, none achieved this result spontaneously. 6. Palliative treatment of the sequelae of birth palsies is difficult, and the results obtained are rarely totally satisfactory. It is for these reasons that the initial surgical intervention should be on the plexus itself in those instances meeting the criteria established above. It is important to make this decision as quickly as possible before neuroplasticity is diminished and joint contractions have occurred.

Brachial Plexus↗
PubMed1991

A comparison of suture and tubulization nerve repair techniques in a primate.

This study compared standard methods of nerve repair, epineurial or perineurial sutures with a technique termed fascicular tubulization using a biodegradable polyglycolic acid tube in a nonhuman primate model. Electrophysiologic analysis demonstrated that the percentage of proximal axons that conducted across the repair site did not significantly differ among the three techniques while epineurial suture repairs were associated with significantly longer conduction delays across the repair site compared with the other two techniques. Even though fascicular tubulization using the current polyglycolic acid tube resulted in regeneration equal to the currently perceived best suture repair technique, associated technical problems with the current tube design indicate that this fascicular tubulization technique cannot, at present, be considered as an alternative to present clinically used nerve suture techniques.

Animals↗
PubMed1989

Fascicular tubulization: a comparison of experimental nerve repair techniques in the cat.

Peripheral nerve repair remains one of the most difficult problems in hand surgery; the results of conventional epineurial and fascicular suture repair are a major limitation to the rehabilitation of the patient. The aim of this study was to evaluate a tubulization technique of nerve repair by wrapping a membrane of hypoantigenic collagen around the nerve at the fascicular level. Cat ulnar and median nerves were used as a multifascicular nerve model. Thirty-eight animals were studied. Ten animals were included in long-term studies comparing fascicular tubulization to either epineurial suture or fascicular suture nerve repair. Histologically, the tube repairs demonstrated improved organization at the repair site compared with either suture technique. Tube repair is not significantly different statistically by quantitative histological and physiological evaluation methods from epineurial suture or fascicular suture repairs. Further studies in more clinically applicable animal models are required before this technique can be considered as an alternative to present clinical nerve suture techniques.

Action Potentials↗
PubMed1989

Experience with the island radial forearm flap in local hand coverage.

Use of the island radial forearm flap (RFF) for soft-tissue coverage of hand and forearm following mutilating injuries, chemotherapeutic injection sloughs, and tumor excisions are discussed. Twenty-eight flaps were used in 28 injured upper extremities. Partial flap loss occurred in three patients. Minor sloughing of the skin graft of the donor site occurred in four. Twelve patients had persistent dysesthesias and paresthesias in the injured extremity. All patients complained of some degree of weakness in the injured extremity. Our experience supports the use of this flap for local hand and forearm coverage when local tissue is unavailable and skin grafting is deemed inadvisable. Donor site problems have been acceptable in our patient population.

Adolescent↗
PubMed1989

Artificial nerve graft compared to autograft in a rat model.

A study was made to compare the regeneration of rat peroneal nerve across a 0.5 cm gap repaired with a sutured autograft (SAG) versus an artificial nerve graft (ANG). The ANG model is composed of a synthetic biodegradable passive conduit made of polyglycolic acid (PGA) and a synthetic growth medium composed of hypoallergenic collagen. Axonal regeneration in short-term animals (1 and 4 months) was evaluated by qualitative histology only, while in long-term animals (17 to 21 months) quantitative histology and electro-physiology were used in addition to qualitative histology. This study reveals that axons do regenerate through this ANG model, but electrophysiological analyses show that the axonal regeneration is statistically inferior to that in the SAG. There was no significant statistical difference in the quantitative histological data.

Animals↗
PubMed1989

Effect of low frequency low energy pulsing electromagnetic field (PEMF) on X-ray-irradiated mice.

C3H/Km flora-defined mice were used to investigate the effect of exposure to pulsing electromagnetic field (PEMF) after total body x-ray irradiation. Prolonged exposure to PEMF had no effect on normal nonirradiated mice. When mice irradiated with different doses of x-ray (8.5 Gy, 6.8 Gy, and 6.3 Gy) were exposed to PEMF 24 h a day, we observed a more rapid decline in white blood cells (WBC) in the peripheral blood of mice exposed to PEMF at all the x-ray dosages used. No effect of exposure to PEMF was observed on the survival of the mice irradiated with 6.3 Gy and 8.5 Gy; in mice irradiated with 6.8 Gy, 2 out of 12 survived when exposed to PEMF as compared to 10 out of 12 control mice that were irradiated only. At day 4 after irradiation autoradiographic studies performed on bone marrow and spleen of 8.5-Gy-irradiated mice showed no difference between controls and mice exposed to PEMF, whereas on 6.8-Gy mice the bone marrow labeling index was lower in mice exposed to PEMF. In mice irradiated to 6.3 Gy we observed that the recovery of WBC in the peripheral blood was slowed in mice exposed to PEMF and their body weight was significantly lower than in control mice that were irradiated only. The spleen and bone marrow of the mice irradiated to 6.3 Gy and sacrificed at days 4, 14, 20, and 25 after irradiation were analyzed by autoradiography to evaluate the labeling index. Half of the spleens from mice sacrificed at day 25 after irradiation were used to evaluate the RNA content. Autoradiography showed that in the spleen and bone marrow of control mice, there were more cells labeled with [3H]thymidine at days 4 and 14 and less at days 20 and 25 after irradiation in comparison with mice irradiated and exposed to PEMF. The Northern blot analysis of histone H3 and p53 protein RNAs extracted from the spleens at day 25 after irradiation showed a slight increase in cycling cells among spleens of mice exposed to PEMF. We suggest that the exposure to PEMF immediately after x-ray irradiation results in increased damage.

Animals↗
PubMed1989

Digit replantation applying the leech Hirudo medicinalis.

Digits that were formerly assessed as nonreplantable may now be replanted with the help of the leech Hirudo medicinalis. The early experience with a series of patients who had relative contraindications for replantation is reported. In each case, venous repair was either marginal or technically impossible. Postoperative venous congestion developed following replantation and was treated with the application of medicinal leeches. Patient acceptance was high, and no infections developed. No patient required transfusion. The authors conclude that the use of medicinal leeches shows promise as a safe and effective method of providing temporary venous drainage in replanted digits.

Adolescent↗