Zhongyu Li

Schwann cells are integral to the regenerative capacity of the peripheral nervous system, which declines after adolescence. The mechanisms underlying this decline are poorly understood. This study sought to compare the protein expression of Notch, c-Jun, and Krox-20 after nerve crush injury in adolescent and young adult rats. We hypothesized that these Schwann cell myelinating regulatory factors are down-regulated after nerve injury in an age-dependent fashion. Adolescent (2 months old) and young adult (12 months old) rats (n = 48) underwent sciatic nerve crush injury. Protein expression of Notch, c-Jun, and Krox-20 was quantified by Western blot analysis at 1, 3, and 7 days post-injury. Functional recovery was assessed in a separate group of animals (n = 8) by gait analysis (sciatic functional index) and electromyography (compound motor action potential) over an 8-week post-injury period. Young adult rats demonstrated a trend of delayed onset of the dedifferentiating regulatory fac...

The arteriovenous anastomoses (AVA) of the cutaneous microcirculation of the hands and feet are fundamental determinants of thermoregulatory blood flow and may be involved in cold intolerance. These direct microvascular studies are an initial characterization of adrenergic receptor subtypes participating in control of AVA in the ears of anesthetized male New Zealand White rabbits. Adrenergic alpha 1-stimulation with phenylephrine produced AVA constriction, whereas terazosin (an alpha 1-antagonist) produced dilation and attenuated the responses to phenylephrine. Adrenergic alpha 2-stimulation with UK-14304 produced constriction of the AVA, whereas atipamezole (an alpha 2-antagonist) produced dilation and attenuated the responses to UK-14304. When equimolar concentrations of antagonists were studied, the AVA dilation produced by alpha 2-blockade was greater than that produced by alpha 1-blockade. Norepinephrine (a mixed alpha 1- and alpha 2-agonist) also produced vasoconstriction, which was attenuated by both prazosin (an alpha 1-antagonist) and atipamezole. In summary, 1) AVA contain a heterogeneous mixture of both alpha 1- and alpha 2-receptors, and 2) alpha 2-receptors may have a greater influence than alpha 1-receptors on overall tone in AVA.

Arthrodesis and arthroplasty are surgical options used for the management of pain, stiffness, deformity, and instability related to arthritis and traumatic injury of the small joints of the hand. Arthrodesis and arthroplasty come with a risk of postoperative infection. Superficial soft tissue infections can often be managed with oral antibiotics alone. Deep infections and osteomyelitis frequently require removal of hardware in addition to antibiotics and may require surgical revision once the infection is cleared. Selection of the most appropriate revision technique depends on the underlying cause of the initial failure, patients' functional and outcome needs, and surgeon preference.

Two patients with an anteriorly positioned ulnar nerve at the elbow, identified during cubital tunnel release, are presented. Upon encountering an empty cubital tunnel, additional dissection found the ulnar nerve to course posterior to and to penetrate through the intermuscular septum 3 to 5 cm proximal to the medial epicondyle. It then ran anterior to the pronator-flexor mass before entering the forearm between the ulnar and the humeral heads of the flexor carpi ulnaris. Although a rare anatomical anomaly, an anteriorly positioned ulnar nerve is potentially an underreported finding. In individuals with cubital tunnel syndrome, diagnosis and surgical treatment may be negatively affected if the surgeon fails to recognize the aberrant anatomy. Upper extremity surgeons should also be mindful of this rare anomaly when performing elbow arthroscopy or medial epicondyle release to prevent inadvertent injury to the nerve.

To determine in a cadaveric model which of 3 anterior transposition techniques allows for maximum gap reduction for high ulnar nerve lesions. Six fresh-frozen human adult upper extremity cadaveric transhumeral specimens were used. We anchored the ulnar nerve to bone 10 cm proximal and distal to the medial epicondyle along its exact course while keeping the elbow in 30° flexion as the baseline measurement. We then used a thick suture to mimic and measure the exact course of the nerve between the pins in varying elbow positions. The nerve was then transposed first subcutaneously, then intramuscularly, and then submuscularly while taking exact measurements of the distance the nerve had to travel in varying degrees of elbow flexion for each transposition method. We performed comparative analysis to analyze gap reduction with respect to transposition method and elbow position. Transposing the ulnar nerve reduced the repair gap required to cross the elbow regardless of transposition technique. When comparing individual techniques, however, the greatest gap reduction was achieved by intramuscular, followed by submuscular and finally subcutaneous transposition. A maximum gap reduction of 25 mm (average, 23 mm) was achieved using intramuscular transposition with the elbow in 90° flexion. Subcutaneous transposition actually increased the repair gap when the elbow was in an extended position. An intramuscular transposition with the elbow in 90° flexion provided the best gap reduction. However, post-neurorrhaphy mobilization may compromise repair site integrity and vascularity if elbow flexion is required to achieve a primary repair, and these factors should be considered carefully when planning treatment. This study provides guidance on techniques to reduce nerve gap for primary repair of the ulnar nerve at the elbow using transposition and elbow flexion.

ABSTRACT Limited evidence exists to guide clinical management of acute finger ischemia (AFI). To further inform diagnostic evaluation and decision making, we evaluated anatomic findings, procedural management, and amputation-free survival in an institutional cohort of patients with AFI. Consecutive patients undergoing transfemoral upper extremity angiography for AFI were identified. Clinical, laboratory, and procedural data were collected retrospectively from medical records, and arteriograms were reviewed to characterize anatomic findings. Telephone interviews were used to determine long-term outcomes, and additional symptomatic assessments (Symptom Severity and Functional Status scale, the Cold Sensitivity Severity scale, and the McGill Pain Severity Scale) were available in a subgroup of patients. Outcomes included anatomic findings, use of thrombolysis, complications, and amputation-free survival. Descriptive statistics and survival analysis were used to evaluate results. Thirty-five patients (54% women) were analyzed with a median follow-up of 13.7 months. Symptom duration at time of presentation ranged from 1 to 28 days, and seven patients had tissue loss or gangrene, or both. Mean age was 47.7 ± 12.2 years. Baseline characteristics included smoking in 22 (65%), connective tissue disorder in 11 (31%), and history of repetitive hand trauma in 10 (29%). The most frequent anatomic location of arterial pathology identified during angiography was distal to the wrist (n = 32), including eight ulnar/radial aneurysms; upper arm (n = 3) and forearm (n = 8) lesions were less common. Sixteen patients were treated with catheter-directed thrombolysis, of which eight (50%) had interval anatomic improvement on repeat angiography. Procedure-related adverse events associated with angiography included bleeding (n = 3) and pseudoaneurysm (n = 1). Eleven of 35 patients had subsequent surgical revascularization at a median of 15 days after angiography. Estimated (standard error) amputation-free survival was 0.88 (0.07) at 1 month and 0.84 (0.08) at 6 months among patients without tissue loss or gangrene. Estimated 60-day amputation-free survival was 0.84 (standard error, 0.08). Overall amputation-free survival was similar between patients managed with vs without thrombolysis (P = .61), but subgroup analysis of those patients without tissue loss or gangrene at the time of presentation revealed a trend toward improved amputation-free survival with use of thrombolysis, with 60-day amputation-free survival of 0.92 vs 0.75 (P = .12). Persistent late symptoms were present in 17 patients (48.6%) at the last follow-up and were generally characterized as mild by functional and pain scale assessments. Angiography performed for AFI frequently identifies distal occlusive disease, and catheter-directed thrombolysis may expand revascularization options in select patients.

Patients with critical peripheral vascular disease and nonhealing toe ulcers secondary to collagen vascular disease often require toe amputation when nonsurgical measures fail to control their symptoms. The aim of this study was to evaluate the effectiveness of periarterial sympathectomy (PAS) of the foot/ankle in patients with unreconstructable vaso-occlusive disease and nonhealing digit ulcers unresponsive to nonsurgical measures. Five patients (seven feet and nine toe ulcers) were treated with PAS of their involved foot and followed for a minimal of 3 years (3 to 7 years). The technique included PAS of the dorsalis pedis, posterior tibial and anterior tibial arteries. Eight toe ulcers healed uneventfully within 3 months after surgery. Only one patient developed a new ulcer 5 years after PAS. The mean visual analog pain scale improved from 5.7 to 1 (P<0.03). The mean Wake Forest University (WFU) scale improved from 1.8 to 0.5 (P=0.07). There was no change in the WFU numbness score or the McCabe Cold sensitivity scale. The results suggest that foot/ankle PAS is a beneficial salvage treatment option for patients with non-reconstructable, vaso-occlusive disease that ameliorates foot symptoms, facilitates healing of toe ulcerations, and reduces the incidence of toe amputations.

The clinical effects of peripheral sympathectomy on patients with vaso-occlusive disease are often dramatic and include relief of pain, improved quality of life, and healing of ulcers. Peripheral periarterial sympathectomy is known to increase skin temperature and to maximize the nutritional component of peripheral blood flow, but the pathophysiology of vaso-occlusive disease and the physiologic mechanisms of this treatment are unknown. In this study, the acute effects of periarterial sympathectomy were directly observed in a rabbit ear model of digital microcirculation (arterioles, arteriovenous anastomoses, and venules). The effects of periarterial sympathectomy on cutaneous perfusion and total flow were also examined using laser Doppler perfusion imaging and digital temperature measurements. The central auricular artery became dilated (50-100%) immediately after sympathectomy; the arterioles, arteriovenous anastomoses, and venules dilated to 165, 156, and 223%, respectively, at 30 minutes and to 187, 174, and 204%, respectively, at 60 minutes, relative to their baseline diameters prior to sympathectomy. Laser Doppler perfusion imaging values and ear temperatures were noted to increase after sympathectomy (8.9%, 3 degrees C), although the core temperature of the rabbit did not change. Thus, acute periarterial sympathectomy can (a) effectively reduce the vascular tone of the distal microvasculature and (b) increase total microcirculatory perfusion-cutaneous and thermoregulatory-by both venular and arteriolar dilation. Periarterial sympathectomy has the clinical potential to increase nutritional blood flow, thereby ameliorating the signs and symptoms of ischemia associated with thermoregulatory abnormalities. Dilation of the arteriovenous anastomoses, with a subsequent reduction in vascular resistance, may contribute to the increased cutaneous temperature noted after sympathectomy.

The treatment of patients with prolonged denervation from a posterior cord brachial plexus injury is challenging and no management guidelines exist to follow. The authors describe the case of a 26-year-old man who presented to our clinic for treatment 11 months after suffering a high-energy injury to the posterior cord of the brachial plexus. A combined 9-cm proximal cable nerve graft procedure and a pronator branch to the posterior interosseous nerve transfer were performed. Satisfactory deltoid, triceps, wrist, and finger extensor recovery was noted 3 years after surgery. Patients with prolonged denervation from posterior cord injuries can be successfully treated with a combination of a proximal nerve graft and a distal nerve transfer.

We describe 2 cases of primary atraumatic venous aneurysm affecting the wrist. Both aneurysms were in branches of the cephalic vein in close proximity to the radial artery. The definitive treatment for these venous aneurysms was surgical excision. There was no recurrence after 9 years in case 1 and after 11 years in case 2. Modern diagnostic modalities were used, including physical examination, Doppler ultrasonography, aspiration, magnetic resonance imaging, and venography. The pathologic analysis was consistent with those venous aneurysms reported in other parts of the body. The hand surgeon should be aware of this rare condition when formulating a differential diagnosis for soft tissue masses of the wrist.

This study tests the hypothesis that major peripheral nerves serve as important routes for adrenergic neural fibers and therefore peripheral nerve injury affects cutaneous perfusion within the nerve's sensory innervation territory. The specific aim of the study was to determine whether an acute isolated peripheral nerve injury would result in alteration of blood flow to a specific digit, digital pain, and/or cold sensitivity. The influence of peripheral nerves on their dominant area of autonomic vasomotor function was evaluated in 9 patients who had primary neurorrhaphy after a single complete median or ulnar nerve transection. At a mean follow-up of 47 days the response of digital perfusion to a cold stress was examined in these patients by using isolated cold stress testing and laser Doppler fluxmetry. Patients also completed subjective questionnaires to evaluate their symptoms. The affected hands showed a decreased cutaneous perfusion when compared with the contralateral hands during all 3 phases of the cold stress test. In addition cutaneous perfusion patterns evaluated by laser Doppler perfusion imaging showed markedly decreased cutaneous perfusion patterns in the digits within the innervation territory of the injured nerve. There was no notable difference in digital baseline temperatures and temperature changes after an isolated cold stress test between the most affected digits of the injured hands and corresponding digits of the unaffected, contralateral hands. All 9 patients reported mild to severe digital numbness, 8 reported mild to severe pain, and 4 reported mild to moderate cold sensitivity of the upper extremity. This study documents that cutaneous perfusion and thermoregulatory function is altered after isolated peripheral nerve injury.

The purpose of this study was to investigate the relative contributions of two proposed mechanisms, strength imbalance and impaired longitudinal muscle growth, to osseous and postural deformity in a rat model of brachial plexus birth palsy (BPBP). Thirty-two Sprague-Dawley rat pups were divided into four groups on the basis of surgical interventions to induce a strength imbalance, impaired growth, both a strength imbalance and impaired growth (a combined mechanism), and a sham condition in the left forelimb. Maximum passive external shoulder rotation angle (ERmax) was measured bilaterally at four and eight weeks postoperatively. After the rats were killed at eight weeks, the glenohumeral geometry (on microcomputed tomography) and shoulder muscle architecture properties were measured bilaterally. Bilateral muscle mass and optimal length differences were greatest in the impaired growth and combined mechanism groups, which also exhibited >15° lower ERmax (p < 0.05; four weeks pos...

Two potential mechanisms leading to postural and osseous shoulder deformity after brachial plexus birth palsy are muscle imbalance between functioning internal rotators and paralyzed external rotators and impaired longitudinal growth of paralyzed muscles. Our goal was to evaluate the combined and isolated effects of these 2 mechanisms on transverse plane shoulder forces using a computational model of C5-6 brachial plexus injury. We modeled a C5-6 injury using a computational musculoskeletal upper limb model. Muscles expected to be denervated by C5-6 injury were classified as affected, with the remaining shoulder muscles classified as unaffected. To model muscle imbalance, affected muscles were given no resting tone whereas unaffected muscles were given resting tone at 30% of maximal activation. To model impaired growth, affected muscles were reduced in length by 30% compared with normal whereas unaffected muscles remained normal in length. Four scenarios were simulated: normal, musc...

Unstable, severely comminuted fractures of the metacarpophalangeal (MCP) joint are difficult to treat. Closed treatment and casting of these fractures often fail to maintain proper alignment and impede wound care where concomitant open injuries such as gunshot wounds are present. Conventional pinning or plating techniques are not feasible if extensive bone loss and comminution are present. A distraction pinning technique represents a potential alternative, but results with this approach, to our knowledge, have not been reported. The purposes of this study were (1) to evaluate the effectiveness (defined as osseous union and joint stability) of distraction pinning for comminuted fractures involving MCP joints after gunshot or crush injuries; (2) to report the short-term results in terms of pain and function in a small group of patients who underwent MCP distraction pinning; and (3) to evaluate complications and return to work status of these patients in the short term. We reviewed 10 ...

Neuromuscular junction destabilization following nerve injury contributes to irreversible functional impairment. Myogenic Regulatory Factors (MRF's) including myoblast determination factor (MyoD), MRF-4, Myogenin, and myogenic factors-5 (myf-5), and Growth-associated protein 43 KDa (GAP43) regulate gene expression of nicotinic acetylcholine receptor (nAChR) subunits (alpha, beta, delta, gamma, and epsilon). We hypothesized that nerve injury induces altered gene expression of MRF's, nAChRs, and GAP-43 in the skeletal muscle which destabilize neuromuscular junctions. The tibial nerve was transected in 42 juvenile male Sprague-Dawley rats. Denervated and contralateral control gastrocnemius m. mRNA for nAChR subunits, MRF's, and GAP-43 were determined by real time reverse transcription polymerase chain reaction (real time RT-PCR). After transection, muscle mass decreased for 1 year with a nadir of 75% at 3 months. Alpha, gamma, and epsilon subunit genes increased by 3 and peaked at 7 days before returning to control levels (P…

Complex hand wounds with exposed tendon or bone often require free tissue transfer. We report results in 13 patients with complex dorsal hand or digital wounds who underwent soft-tissue reconstruction using a turnover adipofascial flap and skin grafting over a 35-month period. The mean patient age was 44 years. Mechanism of injury included the following: three gunshot, four degloving, one table saw, three chain saw, one thumb avulsion, and one crush. Flap sizes varied from 2 × 4 to 10 × 18 cm, involving the dorsum of the hand in four patients, thumb in two patients, index finger in one patient, long finger in three patients, long and ring fingers in one patient, and web space in two patients. Skin graft survival was 100% in 12 patients. One patient died of sepsis from unrelated medical conditions. All fractures were healed at follow-up, and there were no donor site complications. The adipofascial flap is a good alternative to free tissue transfer for the coverage of complex dorsal hand and finger soft-tissue defects and is associated with technical ease, good cosmetic results, and minimal donor site morbidity.

Two mechanisms, strength imbalance or impaired longitudinal muscle growth, potentially cause osseous and postural shoulder deformity in children with brachial plexus birth palsy. Our objective was to determine which muscles, via either deformity mechanism, were mechanically capable of producing forces that could promote shoulder deformity. In an upper limb computational musculoskeletal model, we simulated strength imbalance by allowing each muscle crossing the shoulder to produce 30% of its maximum force. To simulate impaired longitudinal muscle growth, the functional length of each muscle crossing the shoulder was reduced by 30%. We performed a sensitivity analysis to identify muscles that, through either simulated deformity mechanism, increased the posteriorly directed, compressive glenohumeral joint force consistent with osseous deformity or reduced the shoulder external rotation or abduction range of motion consistent with postural deformity. Most of the increase in the posterior glenohumeral joint force by the strength imbalance mechanism was caused by the subscapularis, latissimus dorsi, and infraspinatus. Posterior glenohumeral joint force increased the most owing to impaired growth of the infraspinatus, subscapularis, and long head of biceps. Through the strength imbalance mechanism, the subscapularis, anterior deltoid, and pectoralis major muscles reduced external shoulder rotation by 28°, 17°, and 10°, respectively. Shoulder motion was reduced by 40° to 56° owing to impaired growth of the anterior deltoid, subscapularis, and long head of triceps. The infraspinatus, subscapularis, latissimus dorsi, long head of biceps, anterior deltoid, pectoralis major, and long head of triceps were identified in this computational study as being the most capable of producing shoulder forces that may contribute to shoulder deformity following brachial plexus birth palsy. The muscles mechanically capable of producing deforming shoulder forces should be the focus of experimental studies investigating the musculoskeletal consequences of brachial plexus birth palsy and are potentially critical targets for treating shoulder deformity.

To determine whether transfer to only the anterior branch of the axillary nerve will restore useful function after axillary nerve injury with persistent posterior deltoid and teres minor paralysis. We used a computational musculoskeletal model of the upper limb to determine the relative contributions of posterior deltoid and teres minor to maximum joint moment generated during a simulated static strength assessment and to joint moments during 3 submaximal shoulder movements. Movement simulations were performed with and without simulated posterior deltoid and teres minor paralysis to identify muscles that may compensate for their paralysis. In the unimpaired limb model, teres minor and posterior deltoid accounted for 16% and 14% of the total isometric shoulder extension and external rotation joint moments, respectively. During the 3 movement simulations, posterior deltoid produced as much as 20% of the mean shoulder extension moment, whereas teres minor accounted for less than 5% of the mean joint moment in all directions of movement. When we paralyzed posterior deltoid and teres minor, the mean extension moments generated by the supraspinatus, long head of triceps, latissimus dorsi, and middle deltoid increased to compensate. Compensatory muscles were not fully activated during movement simulations when posterior deltoid and teres minor were paralyzed. Reconstruction of the anterior branch of the axillary nerve only is an appropriate technique for restoring shoulder abduction strength after isolated axillary nerve injury. When shoulder extension strength is compromised by extensive neuromuscular shoulder injury, reconstruction of both the anterior and posterior branches of the axillary nerve should be considered. By quantifying the biomechanical role of muscles during submaximal movement, in addition to quantifying muscle contributions to maximal shoulder strength, we can inform preoperative planning and permit more accurate predictions of functional outcomes.