Biomedical subjects
Publications and source records attributed to A L Van Beek.
This article describes and illustrates the process of nail regeneration and suggests specific management for acute nail bed injuries. The management consists of direct, nail matrix repair and nail matrix split grafting. Postoperative care following nail bed injuries is also discussed.
The use of temporary inflatable implants to generate expanded skin flaps in the upper extremity is a useful reconstructive technique. Applications, technique, and complications are discussed and emphasized with case reports.
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A study to determine the growth potential of immature microvessels was carried out using rat femoral arteries. Immature rat arteries repaired with interrupted 10-0 nylon sutures grew in proportion to the animal. There were no areas of stenosis at repair sites, which in some animals appeared slightly dilated compared with control vessels. The ultrastructure of repaired arteries after growth was mildly altered in the internal and external elastic membrane layers while the intima and media appear normal. Neovascularization around anastomoses may explain an apparent increased blood flow velocity at repair sites and does not correspond to arterial narrowing in this model.
The topography of the intraneural fascicular groups must be understood if the treatment of acute lacerations of the major nerves in the forearm is to be successful. Most lacerations in the upper extremity occur at the wrist and in the distal half of the forearm. With microsurgical longitudinal dissections and serial sections, we studied the intraneural topography of the fascicular groups of the median and ulnar nerves utilizing forty-five fresh frozen or refrigerated specimens. We devised a new technique of light photography to demonstrate the distinct boundaries of the fascicular groups. The intraneural fascicular groups provide the anatomical basis for the recommended surgical techniques of group fascicular repair and nerve-grafting.
Utilization of signal averaging computers to analyze evoked nerve potentials generated by an electrical stimulus is a useful adjunct to clinical evaluation. Currently, somatosensory evoked responses are useful for the evaluation of the peripheral nerve with suspected compression syndromes, neuropathies of unknown etiologies, post-traumatic injuries, neuromas-in-continuity, and brachial plexus injuries. Further refinements in the system will result in increased clinical application of this useful modality. Present data indicate that neuromas with a conduction velocity of less than 10 meters per second or an amplitude of less than one fourth of normal should be considered unfavorable neuromas, and if clinically correlated, resection and repair anticipated. Conduction velocity slowing of greater than 20 meters per second across a potential site of compression neuropathy at the wrist using short-segment study should also be viewed as undesirable and will usually correlate with clinical findings on an abnormal von Frey test. The somatosensory response in compression neuropathy usually correlates better with the clinical finding than with an EMG.
Electrodiagnostic studies of peripheral nerve function remain a valuable adjunct to a thorough clinical examination. The electromyogram and sensory evoked response of the peripheral nerve aid in determining the diagnosis and severity of some neuropathies. The use of signal averaging microprocessors to enhance small evoked responses is adding another dimension in electrodiagnostic studies. This tool provides evaluation of the peripheral nervous system in conjunction with the central nervous system. The intraoperative use of electrodiagnostic studies is readily performed using widely available equipment, but does require a thorough understanding of the equipment used. The equipment, principles, and helpful hints in applying electrodiagnostic techniques to the evaluation of peripheral nerves is reviewed.
The topography of the fascicular group of the ulnar nerve at the wrist and forearm was studied focusing on the motor (muscle) fascicular group. In 109 of 111 specimens studied (98%), the motor fascicular group of the ulnar nerve is located at the ulnar dorsal or straight dorsal position at the wrist and the distal forearm. This motor fascicular group may be identified as a distinct entity up to 90 mm proximal from the level of the radial styloid. The relatively constant location of the motor fascicular group is significant since most lacerations of the major peripheral nerves of the upper extremity are at the distal forearm or the wrist. In the surgical treatment of acute lacerations of the ulnar nerve at these levels, one should direct special attention to the correct identification, matching, and alignment of the motor fascicular group to enhance reinnervation of the intrinsic muscles of the hand.
The experiments described reveal the direct relationship between blood flow and evoked electrical activity in muscle flaps. It is demonstrated that monitoring of EMWs will detect vascular occlusion to a muscle flap within 1 hour. Detecting failure this soon provides the surgeon an opportunity for reexploration and salvage of a muscle flap before irreversible change has occurred. Correlations with observed muscle contraction and intramuscular temperature changes are also made.
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Following microneurorrhaphy, sharply transected rat sciatic nerves were harvested 2, 5, 12, 16, 21, and 30 days after repair. Transverse sections of these specimens were made 3, 5, 7, 9 and 11 mm distal to the repair and examined with the scanning electron microscope. Myelinated sprouts were found 3 mm distal to the repair on the fifth day. Sprout migration occurred even though old myelin sheaths were present. Sprouts did not appear in old myelin sheath lumens. Many 5 U myelinated sprouts were found 11 mm distally 21 and 30 days after repair. This study demonstrates that nerve regeneration begins early, before degeneration is complete.
Traumatic or thermal injury to the hand may result in a composite tissue loss. Exposed tendon, bone, or joint surface is best treated by flap coverage. This paper will discuss four types of alternative hand flaps that can be used to treat difficult areas and/or minimize complications. (1) A thumb flap elevated from the metacarpophalangeal joint flexion crease covers a fingertip injury and the donor site is closed primarily. (2) A proximally based side-finger flap, preferably from the ulnar side of the donor finger, can be used to cover a fingertip defect in a young person or a thumb tip in any age. (3) A deepithelized cross-finger flap, flipped 180 degrees upside-down, can cover a defect on an adjacent finger. The under side of the flap and the donor area are skin grafted. (4) A proximally based arterialized side-finger flap, including the digital artery but sparing the digital nerve, is rotated dorsally to cover a secondarily exposed proximal interphalangeal joint in burn patients where adjacent fingers are not available as donor sites.
One method for objectively assessing microcirculatory hemodynamics is to determine flow velocity using an ultrasound flow probe. The velocity acceleration measured at the site of repair was previously thought to be caused by stenosis. This study failed to demonstrate anastomotic narrowing and, more important, failed to predict delayed vascular thrombosis. The persistent problem of delayed microvascular thrombosis following replantation and even free-tissue transfer emphasizes the importance of continuing the search for an objective, intraoperative method of detecting venous and arterial repairs that are likely to develop delayed thrombosis.
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The perionychium includes the nail and surrounding structures. The anatomy and physiology of the perionychium is presented in detail. Microscopic examination reveals the nail production to take place on the dorsal roof of the nail fold, the ventral floor of the nail fold, and on the nailbed to the free margin of the nail. The arterial supply is by two dorsal terminal branches of the proper digital artery and the nerve innervation by dorsal terminal branches of the proper digital nerve.
The most common bite injury in the United States is that of the dog and is associated with serious social and economic problems. Our series of 61 dog bite patients shows a majority of them to be in children and of the face and neck. Our treatment protocol centers on copious saline pressure irrigation, meticulous wound and wound edge debridement, repeated copious saline pressure irrigation, adequate antibiotic treatment, and close postoperative monitoring. Two hundred fifteen dog bite wounds in 61 patients were closed with this regimen with only a single wound infection. This is a wound infection rate of 0.47% and a patient infection rate of 1.6%.
We have used 107 V-Y advancement flaps in 76 patients with only loss of one flap and loss of hair growth in a second. The versatility of this method of closure and its superior cosmetic result recommend it to the plastic surgeon who must close defects of the face.