Anatomic study of the ulnar nerve and related vascular anatomy at Guyon's canal: a practical classification system.

Thirty-one fresh adult upper extremities were microdissected in order to delineate the regional anatomy of the ulnar nerve and artery at the wrist. Two patterns of division of the ulnar nerve trunk were identified: A and B. Three patterns of hypothenar muscle innervation-type 1, 2, and 3- and two patterns of vascular supply to the hypothenar musculature-type 1 and 2-were also identified. Pattern A occurred in 25 of the specimens where the ulnar nerve bifurcated into a main sensory trunk and a motor branch. Pattern B occurred in 6 of the specimens where the ulnar nerve trifurcated into two common digital sensory branches and a motor branch. The hypothenar innervation patterns were categorized as follows: type 1, 10 cases, single branch; type 2, 14 cases, two branches; and type 3, 7 cases, three or more branches. The patterns of hypothenar vascular supply were categorized as follows: type 1, 17 cases, major vascular arcade passing from the ulnar artery to the hypothenar musculature palmar to the entire ulnar nerve; type 2, 6 cases, arcade passing palmar to the motor portion of the nerve only; and type 3, 8 cases, no axial arterial supply identified. In no specimen did we identify a deep branch of the ulnar artery coursing with the deep motor branch of the ulnar nerve and contributing to a deep palmar arterial arcade. This classic description of a deep palmar arterial arch, we believe, is not valid, due to the mistaken identity of hypothenar arterial branches.

Comparison of rigid plate versus wire fixation in the management of zygoma fractures: a long-term follow-up clinical study.

We evaluated retrospectively 101 patients to assess clinically the results of fixation methods on isolated unilateral zygoma fractures (mean follow-up 3.2 years). All patients were examined by an investigator who was blinded to the initial fixation method. Ninety-two patients were treated with wire or plate fixation alone. The major clinical parameters assessed were globe position abnormalities (enophthalmus and dystopia), malar projection, and cheek sensation. Rigid plate fixation achieved statistically better long-term malar symmetry (p = 0.002) and approached statistical significance in the achievement of more normal globe position (p = 0.06) compared with wire fixation alone. Cheek sensation showed a nonsignificant trend (p = 0.13) toward improvement with plate fixation. Other parameters that were evaluated were anatomic location of fixation points, number of fixation points, surgical approach and exposure, and breakdown of fixation dates by specialty. None of these factors showed any significant influence on outcome. The present study confirms what we have known to be true from our clinical experience--that rigid internal fixation is superior in minimizing or preventing long-term sequelae of facial fractures.

Muscle recruitment variations during wrist flexion exercise: MR evaluation.

OBJECTIVE: Many exercise protocols used in physiological studies assume homogeneous and diffuse muscle recruitment. To test this assumption during a "standard" wrist flexion protocol, variations in muscle recruitment were assessed using MRI in eight healthy subjects. MATERIALS AND METHODS: Variations were assessed by comparing the right to the left forearms and the effect of slight (15 degrees) pronation or supination at the wrist. RESULTS: Postexercise imaging showed focal regions of increased signal intensity (SI), indicating relatively strong recruitment, most often in entire muscles, although occasionally only in subvolumes of muscles. In 15 of 26 studies, flexor carpi radialis (FCR) showed more SI than flexor carpi ulnaris, while in 11 studies SI in these muscles increased equivalently. Relatively greater FCR recruitment was seen during pronation and/or use of the nondominant side. Palmaris longus, a wrist flexor, did not appear recruited in 4 of 11 forearms in which it was present. A portion of the superficial finger flexor became hyperintense in 89% of studies, while recruitment of the deep finger flexor was seen only in 43%. CONCLUSION: Inter- and intraindividual variations in forearm muscle recruitment should be anticipated in physiological studies of standard wrist flexion exercise protocols.

Muscle proton T2 relaxation times and work during repetitive maximal voluntary exercise.

We studied the effects of progressive maximal voluntary handgrip contractions (MVCs) on muscle proton spin-spin (T2) relaxation times and work, measured as the integrated force vs. time curve (FTI). Six healthy volunteers performed 10, 20, 40, and 80 MVCs in a 0.35-T magnet on four separate occasions. Repeated measures analyses of variance of increases in T2 and FTI during successive bouts were significant (P < 0.005 and P < 0.001, respectively). FTI increased with successive bouts to a greater extent than did muscle T2 (P < 0.05). For T2, the Helmert contrast judged the 10-MVC response lower than the mean of the remaining responses (P < 0.005), and the differences between all others compared with the means of subsequent responses were not significant, indicating a "flattening" of the T2 response after the increase from 10 to 20 repetitions. For FTI, all the single degree of freedom Helmert contrasts were significant (P < 0.001), indicating a continual increase in response over increased MVCs. The curved nature of the T2 response conformed best to a hyperbolic function, suggesting that a limit of approximately 32% exists for the change in T2 during progressively longer bouts of MVCs. A limit in the T2 response is consistent with the existence of a limit in the amount of water that muscle can take up from the vasculature during exertion.

Denervated human skeletal muscle: MR imaging evaluation.

Because determination of neurologic integrity after severe limb trauma is crucial in patient care, the authors assessed magnetic resonance (MR) imaging as a tool to map denervated motor units of skeletal muscle in patients with traumatic peripheral neuropathy. Denervation was confirmed in 22 patients with use of electromyography, surgery, or both. MR imaging was performed with moderately T1- and T2-weighted spin-echo and short-tau inversion-recovery (STIR) sequences. MR imaging was unreliable in depicting acute denervation. Muscles of patients with subacute denervation had prolonged T1 and T2, which contributed to conspicuous hyperintensity on STIR images. Chronically denervated muscles showed marked atrophy, variable changes on STIR images, and conspicuous fatty infiltration on T1-weighted images. Normal variants in motor unit anatomy were seen in denervated muscle volumes outside the expected distribution of the injured nerve. MR imaging is promising for the noninvasive mapping and monitoring of denervated muscle in subacute and chronic phases of peripheral neuropathy.

Soft tissue coverage for the upper extremity.

Soft tissue coverage of the upper extremity continues to be a challenging and evolving field. The expeditious and reliable methods of soft tissue coverage currently in use are discussed with reference to their shortcomings and advantages. For soft tissue coverage of fingertip injuries, open treatment or local flaps from the hand remain the mainstay of treatment. For dorsal and volar hand defects, distal axial flaps, such as the groin flap or microvascular tissue transfer, are utilized most commonly. For large defects proximal to the wrist, trunk axial pattern flaps, microvascular transfer, or the radial forearm flap have the greatest utility. Finally, technical points necessary for the success of some of the flaps are discussed.

Finger-specific flexor recruitment in humans: depiction by exercise-enhanced MRI.

To evaluate the spatial distribution of human forearm musculature stressed by finger-specific exercise, magnetic resonance imaging was performed in conjunction with exercise protocols designed to separately stress the flexor digitorum superficialis and flexor digitorum profundus. These muscles were shown to consist of subvolumes selectively recruited by flexion of the individual fingers. Knowledge of the finger-specific regions of muscle recruitment during finger flexion could improve sampling accuracy in electromyography, biopsy, magnetic resonance spectroscopy, and invasive vascular sampling studies of hand exercise.

Optimizing the management of orbitozygomatic fractures.

Our understanding of the biomechanics and current management of orbitozygomatic fractures has evolved with the development of craniomaxillofacial surgery. Early management was minimal, with reduction alone as the uniform treatment, and the only variation was the approach used. However, a critical review of the literature using these methods revealed that many of these fractures were unstable after simple reduction alone. Using the principles of craniofacial surgery, our clinical experience, and the data presented in this article, a pragmatic algorithm for optimizing the management of orbitozygomatic fractures is presented. Our approach to this problem has been graduated, with orbitozygomatic fractures being divided into two general categories: nondisplaced and displaced. The nondisplaced orbitozygomatic fracture is treated nonoperatively, with close patient follow-up to detect signs of malunion. Displaced fractures are openly reduced and rigidly fixed internally with mini- and/or microplates. The orbit is routinely explored, especially in high-velocity injuries. The orbit is anatomically as well as volumetrically reconstructed with bone grafts, if needed, to prevent postoperative enophthalmos.

The effect of vitamin C on the rapid induction of aortic changes in rabbits.

Male rabbits were injected intraperitoneally for five consecutive days with one of the following: (A) 0.3 ml/kg dimethyl ethylene glycol (solvent); (B) 40 mg/kg cholesterol and 8 mg/kg ergocalciferol in solvent; (C) same regimen as B with the addition of 150 mg/kg ascorbic acid in water. Daily blood samples were taken for determination of cholesterol and triglycerides, and for lipoprotein electrophoresis. After 5 days of injections, histological sections were made of the aorta at the arch. After 5 days, group B, as compared with group A, had higher serum cholesterol (150 ng/dl vs. 50 mg/dl, p less than 0.005), higher serum triglycerides (650 mg/dl vs. 150 mg/dl, p less than 0.01), and lower high-density lipoprotein (16% vs. 35%, p less than 0.05). On autopsy, discontinuous elastic fibers and intimal damage were seen in sections of the aortas from group B, but not from group A. After 5 days, group C had control levels of cholesterol (55 mg/dl) and triglycerides (160 mg/dl), and no significant difference from the control lipoprotein profile. Injections of cholesterol alone showed a slight induction of aortic lesions and blood chemistry changes. No alterations in these parameters were induced by ergocalciferol alone. The data indicate a prophylactic effect of vitamin C on the biochemical and histological changes rapidly induced by cholesterol and ergocalciferol.