Muscle atrophy continues after early cast removal following tendon repair

We studied soleus (SOL), plantaris (PLN), and gastrocnemius (GST) muscles to determine whether early cast removal minimizes muscle atrophy or permits recovery from atrophy after tendon repair. After right tendocalcaneus (Achilles tendon) was transected and repaired, rabbit right hindlimbs were immobilized with the ankle plantar flexed and the knee flexed to 90°, Rabbits were maintained in the cast and sacrificed at 5, 15, or 21 days postoperatively or the cast was removed on day 5 and the animals sacrificed at day 15 or 21. SOL, PLN, and GST muscles of both limbs were removed and weights, mean fiber cross-sectional area, and percentage of Type I fibers and increased the percentage of Type IIc fibers. Ten days after cast removal (i. e., postoperative day 15), SOL muscle atrophy and fiber composition did not differ significantly from continuously immobilized controls. However, 16 days after cast removal (i. e., postoperative day 21), SOL muscle fiber cross-sectional area and fiber composition were near normal, differing significantly from continuously casted controls. At each of the time intervals studied, PLN (containing many glycolytic fibers) did not atrophy as much as SOL (containing mainly oxidative fibers). Our results indicate that (1) early cast removal prevents atrophy of PLN glycolytic fibers, but not oxidative fibers in either PLN or SOL, and (2) early cast removal promotes recovery from atrophy of both oxidative and glycolytic fibers. In spite of the many differences between rabbits and humans, these findings suggest that, although early cast removal may not prevent oxidative muscle fiber atrophy after postoperative immobilization, it may facilitate recovery from atrophy. © 1992 Wiley-Liss, Inc.     

医用生物材料在肌腱损伤后粘连修复中的应用

背景：选用何种生物材料预防肌腱粘连,是目前医学界研究的热点。 目的：总结近年生物材料在肌腱损伤术后粘连修复中的应用现状。 方法：由作者应用计算机检索1999-01/2009-10维普数据库,选择生物材料修复肌腱损伤术后粘连的有关文章,共入选相关文献30篇。 结果与结论：几丁糖具有良好的生物学特性,是一种无毒、无刺激性、无抗原性、组织相容性良好、在体内可降解吸收的新型医用生物材料,具有显著预防肌腱粘连作用。医用生物蛋白胶具有优良的止血与封闭作用、良好的生物相容性、生物降解功能,一定的杀菌作用,可减少和控制创伤炎症反应。大量临床研究及动物实验研究显示医用透明质酸钠、明胶海绵、糜蛋白酶等均具有防止术后组织粘连的作用。     

Immobilization-induced hypersensitivity associated with spinal cord sensitization during cast immobilization and after cast removal in rats

This study examined mechanical and thermal hypersensitivity in the rat hind paw during cast immobilization of the hind limbs for 4 or 8 weeks and following cast removal. Blood flow, skin temperature, and volume of the rat hind paw were assessed in order to determine peripheral circulation of the hind limbs. Sensitization was analyzed by measuring the expression of the calcitonin gene-related peptide (CGRP) in the spinal dorsal horn following cast immobilization. Two weeks post immobilization, mechanical and thermal sensitivities increased significantly in all rats; however, peripheral circulation was not affected by immobilization. Cast immobilization for 8 weeks induced more serious hypersensitivity compared to cast immobilization for 4 weeks. Moreover, CGRP expression in the deeper lamina layer of the spinal dorsal horn increased in the rats immobilized for 8 weeks but not in those immobilized for 4 weeks. These findings suggest that immobilization-induced hypersensitivity develops during the immobilization period without affecting peripheral circulation. Our results also highlight the possibility that prolonged immobilization induces central sensitization in the spinal cord.     

Autologous mesenchymal stem cell-mediated repair of tendon.

Mesenchymal stem cells (MSCs) were isolated from bone marrow of 18 adult New Zealand White rabbits. These cells were culture expanded, suspended in type I collagen gel, and implanted into a surgically induced defect in the donor s right patellar tendon. A cell-free collagen gel was implanted into an identical control defect in the left patellar tendon. Repair tissues were evaluated biomechanically (n = 13) and histomorphometrically (n = 5) at 4 weeks after surgery. Compared to their matched controls, the MSC-mediated repair tissue demonstrated significant increases of 26% (p < 0.001), 18% (p < 0. 01), and 33% (p < 0.02) in maximum stress, modulus, and strain energy density, respectively. Qualitatively, there appeared to be minor improvements in the histological appearance of some of the MSC- mediated repairs, including increased number of tenocytes and larger and more mature-looking collagen fiber bundles. Morphometrically, however, there were no significant left-right differences in nuclear aspect ratio (shape) or nuclear alignment (orientation). Therefore, delivering a large number of mesenchymal stem cells to a wound site can significantly improve its biomechanical properties by only 4 weeks but produce no visible improvement in its microstructure.     

Muscle and tendon stiffness in patients with upper motor neuron lesion following a stroke

The objective of this study was to investigate muscle and tendon stiffness in the triceps surae muscles in patients who had previously had a stroke. The participants were 12 men showing slight to moderate degrees of muscle tonus in the affected leg. All patients showed minimal or no overt clinical motor symptoms, and all walked without mechanical aid. Muscle strengths in isometric and isokinetic activities were measured, as was passive resistance during plantarflexion in each leg. Walking speed was also measured. Evaluations of physical performance and muscle tone were made. Muscle and tendon stiffness was calculated from measurements whilst passively stretching during electrical stimulation, separately for each leg. Muscle strength was significantly higher in the non-affected than in the affected leg. Muscle stiffness was significantly higher in the affected leg than in the non-affected leg. Tendon stiffness was significantly higher in the non-affected than in the affected leg. The higher muscle stiffness in the affected leg might enhance the possibility for storing elastic energy during preactivation. Lower tendon stiffness in the affected leg might reduce the development of fatigue in movements at low velocities. Accepted: 13 March 2000     

Investigating the effects of flexor tendon shortening on active range of motion after finger tendon repair

Evaluation of surgical effects is often done using simple cadaver experimentation. This study uses a robotic testbed to estimate the best-case clinical outcomes of flexor tendon shortening during repair surgery on cadaver hands. Nine fresh-frozen cadaver subjects were connected to an extrinsic index finger robotic muscle testbed and measurement system. The flexor digitorum profundus tendons were severed and surgically repaired at different shortening levels. The index finger's extrinsic tendons were robotically actuated using Hill-type muscle models to emulate the muscle force-length relationships. Extensor muscles were then activated to estimate the active range of motion (ROM) of the all-finger joints after surgery. The effects of metacarpophalangeal (MCP) joint extension limits and extensor muscle activation were also investigated. The resulting interphalangeal joint ROM was clinically graded. Active ROM of the finger decreases as tendon shortening increases (), like passive ROM. This results in a clinical reduction of functionality grade from excellent to good at 10 mm of shortening. Blocking MCP joint ROM and extensor activation also showed significant effects on recovered ROM ( and 0.86). Significant two-way interactions were also observed between shortening and MCP joint blocking () and between shortening and extensor activation (). Results support clinical recommendations of limiting shortening to 10 mm. While this article provides additional experimental evidence for current surgical recommendations, it also validates a new robotic-cadaver methodology for predicting active hand recovery in terms of clinical measurements.     

Biologic and mechanical aspects of tendon fibrosis after injury and repair

ABSTRACT

Tendon injuries of the hand that require surgical repair often heal with excess scarring and adhesions to adjacent tissues. This can compromise the natural gliding mechanics of the flexor tendons in particular, which operate within a fibro-osseous tunnel system similar to a set of pulleys. Even combining the finest suture repair techniques with optimal hand therapy protocols cannot ensure predictable restoration of hand function in these cases. To date, the majority of research regarding tendon injuries has revolved around the mechanical aspects of the surgical repair (i.e. suture techniques) and postoperative rehabilitation. The central principles of treatment gleaned from this literature include using a combination of core and epitendinous sutures during repair and initiating motion early on in hand therapy to improve tensile strength and limit adhesion formation. However, it is likely that the best clinical solution will utilize optimal biological modulation of the healing response in addition to these core strategies and, recently, the research in this area has expanded considerably. While there are no proven additive biological agents that can be used in clinical practice currently, in this review, we analyze the recent literature surrounding cytokine modulation, gene and cell-based therapies, and tissue engineering, which may ultimately lead to improved clinical outcomes following tendon injury in the future.     

Fiberoptic bronchoscopic removal of intratracheal pledgetted repair sutures.

This article describes the use of a flexible bronchoscope to remove pledgetted repair sutures within the trachea. The use of a flexible scope to remove densely adherent material is difficult but occasionally necessary.     

脊髓损伤后即刻清除出血对脊髓修复的影响

为了研究大鼠脊髓损伤后即刻清除出血对脊髓修复的影响,将SD雄性大鼠,随机分为对照组、挤压损伤组和挤压损伤加吸除伤处出血组。对照组仅行椎板去除术,挤压组造脊髓挤压伤模型,挤压加吸引组于脊髓挤压伤即刻行吸引术清除中心出血灶。各组于术后30min内、6h、3d和2w行运动功能评分及形态学观察;于6h、72h观察脊髓含水量的变化;用单宁酸-氯化铁方法观察损伤区血管的通畅情况。用大鼠血管内皮细胞特异性抗原RECA的免疫荧光染色观察血管;用HE染色观察脊髓的病理变化。结果显示脊髓挤压伤后立即清除出血可使损伤旁区血流灌注得到明显改善并减轻继发性损伤;脊髓含水量测定结果表明出血灶清除可减轻脊髓水肿;BBB运动功能评分表证明清除出血灶可加快运动功能恢复。上述结果提示脊髓挤压伤即刻吸除出血灶可明显地促进脊髓损伤后的修复。     

Tendon surface modification by chemically modified HA coating after flexor digitorum profundus tendon repair

Carbodiimide derivatized HA (cd-HA) is less soluble in water than normal HA, and therefore has an increased tissue residence time. The purpose of this study was to study the effect of cd-HA gel on gliding and repair integrity during simulated repetitive motion of a repaired tendon in vitro. A total of 36 flexor digitorum profundus (FDP) tendons from six adult mongrel dogs were used and divided into three groups of control, simple HA, and cd-HA. The gliding resistance between the FDP and the proximal pulley, FDS, and bone was measured before laceration and after modified Kessler technique repair at 1, 5, 10, 50, 100, 200, 300, 400, and 500 cycles. After gliding testing, failure load, tendon stiffness, and resistance to gap formation were measured. The results showed from the first cycle to the 10th cycle, there were no significant differences in gliding resistance between the three testing groups (p > 0.05). From the 50th cycle onwards, the friction was significantly lower in the cd-HA gel group than in the control group (p < 0.05). Neither breaking strength, nor tendon stiffness, nor resistance to gap formation of the repairs were significantly different between the three groups (p > 0.05).     

关节镜下半月板成形术后早期感染的诊断和治疗

目的探讨半月板损伤术后膝关节早期感染的诊治要点及临床预后,分析预防措施。方法回顾性分析2015年1月至2018年1月在我院行关节镜微创治疗的225例半月板损伤患者的临床资料,对其中高度怀疑术后发生关节内感染的患者进行诊治。比较治疗前后的血白细胞计数(WBC)、中性粒细胞百分比(NEUT%)、血沉(ESR)及C-反应蛋白(CRP)水平,采用Lysholm评分对膝关节功能进行评价。结果本组患者有4例术后发生膝关节内感染,感染发生率1.7%,其中3例为表皮样葡萄球菌感染,1例为金黄色葡萄球菌感染。经治疗后,膝关节感染症状及体征均消失,感染治愈,膝关节活动无明显受限;WBC、NEUT%、ESR及CRP较治疗前明显下降,并恢复至正常。术后8周Lysholm评分与治疗前相比,差异具有统计学意义(P<0.05)。结论半月板损伤术后关节内感染发生率较低,但得到的重视程度不够,早期介入可获得良好预后;症状缓解后应早期康复锻炼,避免关节僵硬发生。     

Muscle recovery after repair of short and long peripheral nerve gaps using fibrin conduits

Several lines of experimental evidence support an association between facial processing and social cognition, but no direct link between cortical markers of facial processing and complex cognitive processes has been reported until now. In the current study, we tested the hypothesis that cortical electrophysiological markers for the processing of facial emotion are associated with individual differences in executive and social cognition skills. We tested for correlations between the amplitude of event-related potentials (N170) in a dual valence task and participants’ scores on three neuropsychological assessments (general neuropsychology, executive functioning, and social cognition). N170 was modulated by the stimulus type (face versus word) and the valence of faces (positive versus negative). The neural source of N170 was estimated to be the fusiform gyrus. Robust correlations were found between neuropsychological markers and measures of facial processing. Social cognition skills (as measured by three tests: the Reading the Mind in the Eyes test, the Faux Pas test, and the Iowa Gambling Task) correlated with cortical measures of emotional discrimination. Executive functioning ability also correlated with the cortical discrimination of complex emotional stimuli. Our findings suggest that the cortical processing of facial emotional expression is associated with social cognition skills.     

Muscle recovery after repair of short and long peripheral nerve gaps using fibrin conduits

Peripheral nerve injuries with loss of nervous tissue are a significant clinical problem and are currently treated using autologous nerve transplants. To avoid the need for donor nerve, which results in additional morbidity such as loss of sensation and scarring, alternative bridging methods have been sought. Recently we showed that an artificial nerve conduit moulded from fibrin glue is biocompatible to nerve regeneration. In this present study, we have used the fibrin conduit or a nerve graft to bridge either a 10 mm or 20 mm sciatic nerve gap and analyzed the muscle recovery in adult rats after 16 weeks. The gastrocnemius muscle weights of the operated side were similar for both gap sizes when treated with nerve graft. In contrast, muscle weight was 48.32 ± 4.96% of the contra-lateral side for the 10 mm gap repaired with fibrin conduit but only 25.20 ± 2.50% for the 20 mm gap repaired with fibrin conduit. The morphology of the muscles in the nerve graft groups showed an intact, ordered structure, with the muscle fibers grouped in fascicles whereas the 20 mm nerve gap fibrin group had a more chaotic appearance. The mean area and diameter of fast type fibers in the 20 mm gap repaired with fibrin conduits were significantly (P < 0.01) worse than those of the corresponding 10 mm gap group. In contrast, both gap sizes treated with nerve graft showed similar fiber size. Furthermore, the 10 mm gaps repaired with either nerve graft or fibrin conduit showed similar muscle fiber size. These results indicate that the fibrin conduit can effectively treat short nerve gaps but further modification such as the inclusion of regenerative cells may be required to attain the outcomes of nerve graft for long gaps.     

Corpus callosum atrophy and neuropsychological outcome following carbon monoxide poisoning.

This study assessed the effects of carbon monoxide (CO) poisoning on the corpus callosum (CC). Sixty-two CO-poisoned patients had MRI scans and a battery of neuropsychological tests within 24 h (day of exposure) of CO poisoning and at 6 months post CO exposure. Serial quantitative magnetic resonance imaging (QMRI) analysis of the CC was carried out, with the day of exposure scans compared to the 6-month scans. There was no difference between normal subjects' CC and the baseline scans in the CO-poisoned patients. We detected a 15-mm2 loss in the cross-sectional surface area of the CC between baseline and the 6-month follow-up scans. The effect on the CC was generalized atrophy rather than CC subregion-specific changes. Neuropsychological test results performed at baseline and at 6 months did not correlate with the level of CC atrophy. Independent of any CC effects, the patients exhibited impaired memory, attention, and executive functioning on baseline testing, with variable improvement in cognitive function at 6 months. Quantitative MRI analysis allows for the detection of subtle CC changes that may not otherwise be observed following CO poisoning. The long-term effects of CO on the brain have been historically underestimated; however, we found subtle but significant CC atrophy and cognitive impairments following CO poisoning.     

Muscle coactivation before and after the impact phase of running following isokinetic fatigue

Context:

The effects of fatigue on impact loading during running are unclear, with some authors reporting increased impact forces and others reporting decreased forces.

Objective:

To examine the effects of isokinetic fatigue on muscle cocontraction ratios about the knee and ankle during running.

Design:

Cross-sectional study.

Setting:

Neuromechanics laboratory.

Patients or Other Participants:

Female middle-distance runners (age  =  21.3 ± 1.93 years) with at least 5 years of training experience.

Intervention(s):

Participants ran on the treadmill at 3.61 m/s before and immediately after the fatigue protocol, which consisted of consecutive, concentric knee extension-flexion at 120°/s until they could no longer produce 30% of the maximum knee-extension moment achieved in the familiarization session for 3 consecutive repetitions.

Main Outcome Measure(s):

Electromyographic (EMG) amplitude of the vastus medialis (VM), biceps femoris (BF), gastrocnemius (GAS), and tibialis anterior (TA) was recorded using surface electrodes. Agonist∶antagonist EMG ratios for the knee (VM∶BF) and ankle (GAS∶TA) were calculated for the preactivation (PR), initial loading response (LR₁), and late loading response (LR₂) phases of running. Hip-, knee-, and ankle-joint angular displacements at initial foot contact were obtained from 3-dimensional kinematic tracings.

Results:

Fatigue did not alter the VM∶BF EMG ratio during the PR phase (P > .05), but it increased the ratio during the LR₁ phase (P < .05). The GAS∶TA EMG ratio increased during the LR₁ phase after fatigue (P < .05) but remained unchanged during the PR and LR₂ phrases (P > .05).

Conclusions:

The increased agonist EMG activation, coupled with reduced antagonist EMG activation after impact, indicates that the acute decrease in muscle strength capacity of the knee extensors and flexors results in altered muscle-activation patterns about the knee and ankle before and after foot impact.