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Biomedical subjects

M A McClinton

Publications and source records attributed to M A McClinton.

18 recordsLinked to original sources

The effects of free fat grafts on the stiffness of the rat sciatic nerve and perineural scar.

We developed a new quantitative rat sciatic nerve model to test whether free fat grafts can reduce postoperative perineural scar formation. Epineurectomies of sciatic nerves were performed to create scar. The force required to distract the nerve a unit distance was measured after surgery to determine the time of maximal scar formation. Nerve stiffness normalized for rat weight was statistically greater at 2 months after the initial dissection (0.097+/-0.009 g/mm/g rat weight; n = 10 limbs) than rat limbs that had not undergone a previous dissection (0.075+/-0.012 g/mm/g rat weight). Perineural scar thickness was thicker at 2 months than the perineural tissue in preoperative controls. Free fat grafts decreased nerve stiffness at 2 months (0.078+/-0.012 g/mm/g rat weight) in comparison to the contralateral surgical control limb without a fat graft (0.094+/-0.014 g/mm/g rat weight). Free fat grafts reduced the strength of postoperative perineural scar in this surgical model; however, they were associated with an unexpected finding of substantial postoperative neuropathy.

Adipose Tissue

Microarterial anatomy of the lesser toe proximal interphalangeal joints.

Successful free tissue transfer requires detailed knowledge of the pertinent microvascular anatomy of the donor site. The lesser toe proximal interphalangeal joints are a source of vascularized autologous tissue. In 20 adult cadaver feet, the arterial anatomy of the second, third, and fourth toes was studied using colored latex and India ink injection. The second, third, and fourth dorsal metatarsal arteries produced small or absent dorsal digital arteries in 72.5% of distal dissections. The proper digital arteries were 0.93 to 1.37 cm in length. An additional 2.3 to 2.83 cm of length can be gained by use of the plantar metatarsal arteries if the dorsal metatarsal or dorsal digital arteries are inadequate. The diameter of the medial proper digital arteries (range, 1.2-1.26 mm) was larger than the lateral proper digital arteries (range, 0.66-0.99 mm). The proper digital arteries of the lesser toes provide the predominant arterial supply of the proximal interphalangeal joints through a system of transverse and longitudinal arches.

Adult

Infection in the presence of skeletal fixation in the upper extremity.

Infection is infrequent after open fractures of the upper extremity. Treatment begins with prevention through the appropriate use of prophylactic antibiotics, adequate wound debridement, and timely soft-tissue coverage. If infection supervenes, the surgeon must identify the responsible bacteria and administer antibiotics accordingly. Stable fixation is retained. Unstable fixation is removed and skeletal stability restored. Using these principles, infection in the presence of skeletal fixation can be controlled and fracture union achieved.

Anti-Bacterial Agents

The use of dermal-fat grafts.

Recurrent carpal tunnel syndrome is a difficult problem facing hand surgeons today, and its incidence is rising. In selected cases, re-exploration, median nerve neurolysis, and dermal-fat grafting are beneficial. The surgeon should anticipate 30% to 50% absorption of the graft.

Adipose Tissue

The Mitek Mini G2 suture anchor: biomechanical analysis of use in the hand.

We inserted 36 Mitek Mini G2 suture anchors (Mitek Surgical Products, Westwood, MA) into various sites of 14 fresh cadaver hands. A single-strand 0-Ethibond suture (Ethicon, Sommerville, NJ) was threaded through each anchor, inserted into bone, and loaded to failure. In all cases, either the anchor pulled out (11 of 36) or the suture broke (25 of 36). No anchors fractured. We also measured the breaking strength of six types of suture material (without anchors) commonly used by hand surgeons; all failed at much lower loads than those generated in our anchor pullout model. We conclude that the Mitek Mini G2 suture anchor possesses sufficient pullout strength for tendon and ligament fixation in the hand, including the distal phalanx.

Adult

Long-term recovery following surgical treatment for ulnar artery occlusion.

Fourteen patients were surgically treated for ulnar artery occlusion. Digital blood pressure measurements obtained pre- and intraoperatively helped guide the choice between ligation or reconstruction of the ulnar artery following resection of the occluded segment. The digital brachial index (DBI) was derived by calculating the ratio of digital blood pressure to the simultaneous brachial artery pressure. A DBI value of less than or equal to 0.7 was an indication for arterial reconstruction. If the DBI was greater than 0.7, resection of the occluded arterial segment without reconstruction was considered appropriate. Eight patients were treated by arterial reconstruction and six patients were treated with arterial resection. Seven of the eight reconstructed ulnar arteries were patent at follow-up evaluation by Doppler evaluation. DBI measurements obtained at follow-up were compared to preoperative values. In the reconstruction group, DBI change in the small, ring, and index fingers was positive, whereas it was negative in the resection group. Eleven patients indicated improvement from their presurgical status, although over half continued to experience pain on a regular basis. Reports of environmental and contact cold intolerance also showed improvement following surgery. Complaints of pain and cold intolerance were not significantly different between the resection and reconstruction groups at follow-up evaluation.

Arterial Occlusive Diseases

Upper extremity tourniquet tolerance.

Twenty unsedated volunteers were tested to compare the relative tolerance of an arm tourniquet on one side and of a forearm tourniquet on the other. The forearm tourniquet was tolerated an average of 13 minutes (45%) longer and was consistently rated as less painful during and immediately after the test. No subject tolerated the arm tourniquet longer than the forearm tourniquet. Two peaks of discomfort were found, one just before deflation beneath the tourniquet and one in the hand 2 minutes later. Ulnar nerve distribution paresthesias were the earliest changes experienced; however, complete numbness occurred first in the median nerve distribution. Complete paralysis occurred 7 minutes later (24%) with the forearm tourniquet. Pulse rate did not correlate with tourniquet pain, but blood pressure did. No measurable tourniquet-induced edema occurred on either side.

Adult

Tumors and aneurysms of the upper extremity.

A group of surgical abnormalities more diverse than vascular tumors would be difficult to find. These lesions are growths and are identified by cellular or gross appearance. They range in size from tiny glomus tumors to massive arteriovenous fistulas. This article discusses both congenital and acquired types of vascular tumors.

Aneurysm

Drug and alcohol use in emergency hand patients.

Two hundred eleven adult emergency hand patients were prospectively tested over a 1-year period for drug and alcohol use. On admission, blood and urine samples were sent for quantitative alcohol and qualitative toxicology screens, respectively. In 44% of all patients tests were positive for one or more drugs or alcohol. Tests were positive in 43% of those with traumatic injuries. Of patients injured on the job, 33% had positive tests. Tests were positive in 63% of those patients with hand infections. One third of the patients with positive toxicology screens were multiple drug users. These findings have obvious implications for the patient, the physician, and society as a whole.

Adolescent

Bilateral solitary glomus tumors of the hands.

Solitary glomus tumors of the digits are uncommon, comprising only about 2% of all hand tumors. In this report, we present a case report of a patient with bilateral glomus tumors that became symptomatic 4 years apart. No inheritance pattern was apparent for this patient. An extensive literature review did not uncover a similar patient. Because this condition does not appear to be widely recognized, we suggest that it be considered when patients present with bilateral digital pain.

Adult

Microvascular anastomoses in replanted fingers: do they stay open?

Replantation of fingers is a well established procedure following traumatic amputation. Several studies have documented the functional results of replanted digits. Studies have not documented the long-term (greater than 5 yrs) patency of the microvascular anastomosis in the replanted digit. Duplex imaging, a combination of B-mode ultrasound and bidirectional Doppler ultrasound has been shown to visualize vessels 1 mm in diameter. Color enhancement of the ultrasound image is now possible. We evaluated 18 patients with 24 replanted fingers to assess vascular patency. A minimum of five years follow-up was required for inclusion in the study group. Examination showed a patent anastomosis in every case and a Digital-Brachial Index within normal limits in 71% of the digits. Microvascular anastomoses in vessels as small as 1 mm in diameter remain open as long as 11 years following completion. The sophisticated techniques of color enhanced Duplex imaging makes long-term evaluation of these procedures possible in a non-invasive and accurate fashion. The use of such imaging modalities will have an important role in the evaluation of replanted digits and microvascular procedures in general.

Adult

Aneurysms of the upper extremity.

Thirty aneurysms in the upper extremity in 28 patients over the last 10 years are reviewed. Analysis showed that false aneurysms develop from penetrating trauma, while true aneurysms tend to arise in parts of the arterial tree exposed to blunt trauma. Penetrating injury to vessels should be thoroughly explored and repaired. Arterial aneurysm should be included in the differential diagnosis of masses in the upper extremity, especially after trauma. Three-phase radionuclide scanning is a useful tool for evaluating lesions of the distal arterial tree. When an aneurysm is suspected, early treatment is advised. Treatment options of resection and ligation versus reconstitution of vessel flow should be based on preoperative and intraoperative evaluation of circulatory status.

Aneurysm

One hundred tendon grafts for isolated flexor digitorum profundus injuries.

One hundred cases of isolated flexor profundus tendon laceration or rupture were repaired by tendon graft over a 30-year period. Thirteen patients were over 40 years of age with the age range in the study from 1 1/2 to 60 years. Unless the flexor profundus tendon remained in the decussation of the superficialis, all grafts were placed around the superficialis tendon decussation. Measurements of passive tendon excursion were considered critical in the selection of a motor for the tendon graft. All but two profundus graft motors could be passively extended to 30 mm. Average active distal interphalangeal (IP) joint flexion was 48 degrees following surgery. In thirteen patients the results were considered unsuccessful, with loss of greater than 20 degrees from preoperative proximal IP joint flexion or distal IP joint flexion less than 20 degrees. We suggest that, in properly motivated patients, tendon graft replacement of isolated profundus tendon injuries can give satisfactory results even in the older age group.

Adolescent