Xianyou Zheng

S1 nerve is the most efficient nerve rootlet innervating the anal canal and rectum in rats.

Autonomic and somatic components participate in the defecation process in mammals, combining signals from the brainstem and forebrain. The innervation pattern involved in micturition in rats has been well studied, while defecation has been less studied. The aim of the present study was to identify the most important sensory and motor nerves of the anal canal and rectum involved in defecation. The amplitudes of evoked potential of the anal canal and rectum were higher when L6 and S1 ventral rootlets were stimulated, compared with the other segments (ANOVA and Tukey’s post hoc test, all P < 0.05). The S1 segment was more strongly cholera toxin subunit B conjugated to horseradish peroxidase (CB-HRP) positive compared with the other segments (ANOVA and Tukey’s post hoc test, P < 0.05). Ventral spinal rootlets of L6 and S1 mainly contributed to the pressure change in the anal canal and rectum when the ventral spinal rootlets from L5 to S3 were stimulated electrically. In conclusion, many afferent and efferent nerves innervate the anal canal and rectum and are involved in defecation, but the S1 nerve rootlet could be the most efficient one. These results could provide a basis for defecation reconstruction, especially for patients with spinal cord injuries.

Locking Plate Alone versus in Combination with Two Crossed Kirschner Wires for Fifth Metacarpal Neck Fracture

Fracture of fifth metacarpal neck commonly requires open reduction and internal fixation. However, the current methods of internal fixation in fifth metacarpal neck fractures remain unsatisfactory. Patients with fractures of fifth metacarpal neck received open reduction and internal fixation with either locking plate in combination with two crossed Kirschner wires (K-wires) or locking plate alone were evaluated for the clinical outcomes. Clinical outcomes included grip strength, Michigan hand outcomes questionnaire (MHQ), final angulation and range of motion (ROM) one year after treatment. The averages of MHQ scores, final angulation and ROM of fifth metacarpophalangeal joint of plate with K-wire group were more superior to those of plate group (MHQ 96.7 versus 86.6, final angulation 11.8 versus 23.6, ROM 83.3 versus 72.2). The grip strength had no significant difference between two groups. Locking plate in combination with two crossed K-wires is a more optimal method of fixation compared with locking plate alone.

Brain remodeling after chronic median nerve compression in a rat model

Carpal tunnel syndrome is the most common compressive neuropathy, presenting with sensorimotor dysfunction. In carpal tunnel syndrome patients, irregular afferent signals on functional magnetic resonance imaging are associated with changes in neural plasticity during peripheral nerve injury. However, it is difficult to obtain multi-point neuroimaging data of the brain in the clinic. In the present study, a rat model of median nerve compression was established by median nerve ligation, i.e., carpal tunnel syndrome model. Sensory cortex remodeling was determined by functional magnetic resonance imaging between normal rats and carpal tunnel syndrome models at 2 weeks and 2 months after operation. Stimulation of bilateral paws by electricity for 30 seconds, alternating with 30 seconds of rest period (repeatedly 3 times), resulted in activation of the contralateral sensorimotor cortex in normal rats. When carpal tunnel syndrome rats received this stimulation, the contralateral cerebral hemisphere was markedly activated at 2 weeks after operation, including the primary motor cortex, cerebellum, and thalamus. Moreover, this activation was not visible at 2 months after operation. These findings suggest that significant remodeling of the cerebral cortex appears at 2 weeks and 2 months after median nerve compression.

Novel method for restoration of anorectal function following spinal cord injury via nerve transfer in rats

Objectives Nerve transfer has been developed to restore partial function after serious nerve injuries, for example, restoring bladder control after spinal cord injury (SCI). Our aim here was to establish a preclinical proof-of-concept model using nerve transfer for restoring anorectal function after SCI. Setting We used laminectomy to model SCI, and bilateral spinal ventral and dorsal nerve root anastomosis to re-establish connectivity to the anorectal musculature. Methods Multidisciplinary methods were used to assess the anatomical and functional integrity of the alternative spinal-to-anorectal nerve circuit. Adult rats were used to establish the model. Bilateral anterior and posterior L5 nerve roots were surgically matched with anterior and posterior of S1 nerve roots by microscopic anastomosis to establish an artificial rectal reflex arc with complete sensory and motor pathways. Twelve weeks later, we used retrograde nerve tracing and neurohistomorphological analysis to assess anatomical integrity of the new artificial rectal reflex arc. Anorectal manometry was used to assess the function of the new nerve circuit. Results Retrograde tracing with recombinant attenuated pseudo rabies virus indicated that the new neural pathway was successfully established to the anorectal musculature after experimental SCI. Toluidine blue-stained sections of the anastomosis site revealed normal-appearing nerve fiber morphology and regeneration, and transmission electron microscopy revealed myelinated axons. Anorectal manometry revealed significant anorectal functional recovery. Conclusion These results suggest that our model is a feasible first step in developing an alternative reflex pathway after laminectomy at L4 to S2 and shows promise for effective restoration of anorectal function.

Plate versus Kirschner wire fixation in treatment of fourth and fifth carpometacarpal fracture-dislocations: A retrospective cohort study

BACKGROUND Fourth and fifth carpometacarpal fracture-dislocations with unsatisfactory closed reduction commonly require later open reduction and internal fixation. However, the optimal method of internal fixation for these is unknown. The purpose of this study was to determine through objective clinical measures which method is superior for fourth and fifth carpometacarpal fracture-dislocations: a K-wire or a plate. METHODS We conducted a retrospective review of hospital records of patients who had received treatment for fourth and fifth carpometacarpal fracture-dislocations at one hospital between May 2007 and May 2015. A total of 86 patients who had received open reduction either with plate or K-wire fixation were included. Demographic and clinical characteristics of the two groups of patients were collected. Patients received standardised clinical tests one year after fixation. Clinical outcomes included tests of grip strength and scores on the Michigan Hand Outcomes Questionnaire and Disabilities of Arm, Shoulder, and Hand. Students t tests and Chi-square tests were used to statistically evaluate whether plate or K-wire fixation was superior on the clinical variables. RESULTS The two groups were statistically indistinguishable on their demographic and clinical characteristics. Generally, the clinical outcomes of internal fixation were satisfactory. The average DASH and MHQ scores of the K-wire group were superior to those of the plate group (DASH 2.3 versus 9.8, P = 0.01; MHQ 96.7 versus 86.6, P = 0.02). Grip strength was not significantly different between the two groups (89.5 ± 5.8% versus 90.1 ± 4.9%, P = 0.36). CONCLUSIONS This non-randomly controlled, retrospective study suggests that clinical outcomes after K-wire fixation is superior to plate fixation for fourth and fifth carpometacarpal fracture-dislocations. This is especially the case for hand functions related to work. The present results suggest that K-wire fixation is the gold-standard technique for the treatment of fourth and fifth CMC fracture-dislocations.

Is NS-EDTA Effective in Clearing Bacteria From Infected Wounds in a Rat Model?

Background Irrigation is one of the key procedures in open fracture management to eliminate pathogens and prevent infection. Metal ion deprivation could inhibit bacterial adhesins and weaken adhesion to the host tissue. EDTA in solution can competitively bind to a metal ion and thus might be able to inhibit bacterial adhesins. Questions/purposes (1) Is normal saline-EDTA toxic to fibroblasts and endothelial cells? (2) In a contaminated wound rat model, does irrigation with normal saline-EDTA solution decrease the risk of positive bacterial cultures and infection when compared with normal saline and soap solutions? (3) In an infected wound rat model, are fewer surgical débridements and irrigations with normal saline-EDTA solution required to obtain culture-free wounds when compared with normal saline and soap controls? Methods Normal saline-EDTA solution refers to 1 mmol/L EDTA dissolved in normal saline (pH adjusted to 7.4). Normal saline and soap solutions acted as controls. The toxicity of these solutions to fibroblasts and endothelial cells was assessed in vitro by Annexin V/propidium iodide staining and flow cytometer counting (a well-established method to quantitatively measure the number of dead cells). We established contaminated and infected wound models (bone-exposed or not) with either Staphylococcus aureus or Escherichia coli in rats to investigate the efficacy of normal saline-EDTA solution (n = 30 for the contaminated model and n = 50 for the infected model). For contaminated wounds, the proportion of positive bacterial cultures and infections was compared after irrigation and débridement among the three groups. For infected wounds, we performed irrigation and débridement every 48 hours until the cultures were negative and compared the number of débridements required to achieve a negative culture with survival analysis. Results Normal saline-EDTA showed no additional toxicity to fibroblasts and endothelial cells when compared with normal saline (normal saline [97%] versus EDTA [98%] on fibroblasts, p = 0.654; normal saline [97%] versus EDTA [98%] on endothelial cells, p = 0.711). When bone was exposed in the contaminated models, EDTA irrigation resulted in fewer positive bacterial cultures with S aureus (EDTA: 23%, normal saline: 67%, soap: 40%, p = 0.003) and with E coli (EDTA: 27%, normal saline: 57%, soap: 30%, p = 0.032); however, infection risk was only lower with EDTA irrigation (S aureus with EDTA: 10%, normal saline: 33%, soap: 37%, p = 0.039; E coli with EDTA: 3%, normal saline: 27%, soap: 23%, p = 0.038). In the infected wound model, EDTA irrigation resulted in earlier culture-negative wounds (fewer surgical sessions) compared with normal saline and soap solutions (nonbone-exposed wounds infected by S aureus: p = 0.003, infected by E coli: p = 0.001; bone-exposed wounds infected by S aureus: p = 0.012, infected by E coli: p = 0.022). Conclusions After in vitro assessment of toxicity and in vivo evaluation of efficacy, we concluded that normal saline-EDTA is superior to normal saline and soap solution in our laboratory models. Clinical Relevance The use of normal-saline EDTA as an irrigation solution may reduce the infection rate of wounds. Future studies in large animals and humans might prove our observation in rat models that normal saline-EDTA has an advantage over normal saline as an irrigation solution.

Risk Factors of Acute Hand Injuries in Manual Workers: A Case-control study

The purpose of this study was to identify the risk factors of hand injuries in manual workers. Total 1672 manual workers with acute hand injuries who visited our emergency department accompanied by their colleagues from 1 March 2014 to 1 March 2017 were included in this study. One accompanied colleague with identical work task was chosen randomly as control for each patient. The personal characteristics including gender, age, work experience, acute hand injury history, smoking and alcohol consumption were recorded and compared. Finally, we found the history of severe and multiple times of acute hand injuries, high and very high daily alcohol consumption, working experience from one to two years were risk factors for acute hand injuries in manual workers.

Three-screw versus two-screw fixation of distal fragment in fifth metacarpal neck fractures stabilized with locking plate

Fifth metacarpal neck fracture commonly requires open reduction and internal fixation. Locking plate was widely adopted in the treatment of fifth metacarpal neck fracture as first-line choice for fixation. Patients with fifth metacarpal neck fracture receiving locking plate fixation were included for analysis. Features of internal fixation including number of distal and proximal locking screws, diameter of the screws and usage of lag screws were recorded. Clinical and radiographic outcomes included final volar angulation, grip strength, Michigan Hand Outcomes Questionnaire (MHQ) and range of motion (ROM) of fifth metacarpophalangeal joint. Three-screw fixation was less frequently presented in the group with increased volar angulation (≥30 degrees). Consistently, three-screw fixation of distal fragment could improve the prognosis compared with two-screw fixation (MHQ 95.4 ± 5.1 versus 80.4 ± 12.3, ROM 83.5 ± 7.2 versus 69.6 ± 7.7). In conclusion, the metacarpal head should be fixed by three locking screws instead of two locking screws.

Digital Lengthening to Treat Finger Deficiency: An Experience of 201 Digits in 104 Patients

Objectives. We evaluated the results of digital lengthening by distraction and second-stage bone graft. Methods. We treated finger deficiency of 201 digits in 104 patients (68 males, 36 females) by digital distraction and second-stage bone graft. The distraction was performed with a rate of 1 mm/day (for the first ten days) and 0.5 mm/day followed by using a self-designed bilateral tubal-helical external fixator. The mean follow-up period was 42 months (range 6 to 60 months). Results. The mean lengthening was 29.2 mm (range 25 to 40 mm) and 18.7 mm (range 12 to 32 mm) for metacarpal bones and phalanges, respectively. The mean elongation rate was 174.4% (range 145% to 202%) and 184.8% (range 115% to 283%) for metacarpal bones and phalanges, respectively. The static two-point discriminations and SpO2 showed no significant differences before and after distraction. Four complications were observed (two skin ruptures and two phalangeal splitting). No pin tract infection or tendon rupture showed. Digital lengthening improved functions of the hand. Conclusion. Digital distraction and second-stage bone graft is an effective method to compensate disabilities caused by lack of finger length. It could be an alternative plan for patients with thumb deficiency instead of toe-to-thumb transplant and patients with finger deficiency instead of ray resection.

A Descriptive Study of Open Fractures Contaminated by Seawater: Infection, Pathogens, and Antibiotic Resistance

Aims. In this work, the main objectives were to investigate the clinical characteristics and bacterial spectrum present in open fractures contaminated by seawater. Methods. We conducted a retrospective cohort study and included all patients with open fractures from 1st January, 2012, to 31st December, 2015, in our hospital. Patients were grouped based on the presence of seawater contamination in wounds. We compared the infection rate, bacterial spectrum, and antibiotic resistance between the two groups. Results. We totally included 1337 cases of open fracture. Wounds from 107 cases (8.0%) were contaminated by seawater. The wound infection rate of seawater-contaminated group was significantly higher in patients with Gustilo-Anderson Type II and Type III open fractures. The bacterial spectrum from seawater-contaminated wounds was remarkably different from that of the remaining. Antibiotic sensitivity tests revealed that more than 90% of infecting pathogens in seawater-contaminated wounds were sensitive to levofloxacin and ciprofloxacin. Conclusion. Cephalosporin in combination with quinolone was recommended in the early-stage management of open fractures contaminated by seawater.