Extensor Tendon Injury Due to Repetitive Wrist Dorsiflexion: Morphological Study of Extensor Retinaculum and Extensor Tendon

Most etiological studies of extensor tendon injury were based on the normal anatomy of extensor tendon and extensor retinaculum of the wrist. Further understanding of the morphological changes of the extensor tendon and extensor retinaculum during wrist dorsiflexion might contribute to improved and more accurate understanding of the etiology. The morphology of the extensor tendon of the mid-finger and the fourth compartment of the wrist extensor retinaculum was studied by sonography, and the anatomy was studied in 15 extremities from 11 young male cadavers. Compared with anatomical images, ultrasonography provides similar morphological observations of the extensor retinaculum of the wrist and extensor tendon. Ultrasonography findings revealed that as the dorsiflexion angle changed, the extensor retinaculum of the wrist formed different shaped trochleas. The trochlea guides the rotation of the extensor tendon at the wrist, but it does not form a sharp corner with the extensor tendon; thus, the extensor tendon is not compressed. As the dorsiflexion angle increased from 0° to 60°, the length of the trochlea gradually decreases. The shortening of the trochlea length will lead to a smaller frictional contact area between the extensor tendon and the extensor retinaculum. Consequently, the friction is centralized. During wrist dorsiflexion, the extensor retinaculum provides a trochlea for the extensor tendon. Extensor tendon injury of repetitive wrist dorsiflexion might be caused by centralized friction at the small contact area.     

Extensor tendon injuries: acute management and secondary reconstruction

LEARNING OBJECTIVES: After reviewing the article, the participant should be able to: (1) Describe the anatomy of the extensor tendons at the level of the forearm, wrist, hand, and fingers. (2) Recognize variations in the anatomy. (3) Master the hand examination and define the relevant findings in acute injuries of the extensor tendon(s). (4) Delineate the techniques for extensor repair in both acute and secondary (delayed) management. SUMMARY: Extension of the fingers is an intricate process that reflects the combined action of two independent systems. The interossei and lumbricals constitute the intrinsic musculature of the hand. These muscles innervated by the median and ulnar nerves extend the proximal interphalangeal and distal interphalangeal joints and flex the metacarpophalangeal joints. The extrinsic extensors are a group of muscles innervated by the radial nerve, originating proximal to the forearm. The extrinsic digital extensor muscles include the extensor digitorum communis, extensor indicis proprius, and extensor digiti quinti. The digital extensors function primarily to extend the metacarpophalangeal joints, but also extend the proximal interphalangeal and distal interphalangeal joints. Normal extensor physiology reflects a delicate balance between these two unique extensor systems. In the injured hand, a functioning intrinsic system may potentially compensate for an extrinsic deficit. An understanding of the relevant anatomy and an appreciation for the complex interplay involved in extensor physiology is necessary to recognize and manage these injuries.     

Potential of lumbodorsal fascia forces to generate back extension moments during squat lifts

The lumbodorsal fascia (LDF) has been implicated in numerous biomechanical interpretations of low back mechanics as a tissue that provides support to the lumbar spine during demanding load bearing. One hypothesis is that oblique obdominal muscle forces contribute to trunk extensor moment by transforming lateral abdominal tension into longitudinal tension via the LDF. However, a review of the anatomical literature supports the hypothesis that extensor forces in the LDF result from tension within the latissimus dorsi muscle. The purpose of our work was to evaluate the potential of the LDF to generate trunk extensor moment using two mathematical models: one that activated the LDF with the abdominals and another that activated the LDF with the latissimus dorsi. Efforts were made to represent the anatomy as accurately as possible. The results from three subjects performing six squat lifts each, suggested that the potential of the LDF to contribute significant extensor moment has been overestimated. In fact, the issue of whether the LDF is activated by the abdominals or the latissimus dorsi is irrelevant because neither strategy appeared able to generate sizable extensor moments in the type of lift studied.     

An integrative approach to the biomechanical function and neuromuscular control of the fingers

The exquisite mechanical functionality and versatility of the human hand emerges from complex neuro-musculo-skeletal interactions that are not completely understood. I have found it useful to work within a theoretical/experimental paradigm that outlines the fundamental neuro-musculo-skeletal components and their interactions. In this integrative paradigm, the laws of mechanics, the specifications of the manipulation task, and the sensorimotor signals define the interactions among hand anatomy, the nervous system, and manipulation function. Thus, our collaborative research activities emphasize a firm grounding in the mechanics of finger function, insistence on anatomical detail, and meticulous characterization of muscle activity. This overview of our work on precision pinch (i.e., the ability to produce and control fingertip forces) presents some of our findings around three Research Themes: Mechanics-based quantification of manipulation ability; Anatomically realistic musculoskeletal finger models; and Neural control of finger muscles. I conclude that (i) driving the fingers to some limit of sensorimotor performance is instrumental to elucidating motor control strategies; (ii) that the cross-over of tendons from flexors to extensors in the extensor mechanism is needed to produce force in every direction, and (iii) the anatomical routing of multiarticular muscles makes co-contraction unavoidable for many tasks. Moreover, creating realistic and clinically useful finger models still requires developing new computational means to simulate the viscoelastic tendinous networks of the extensor mechanism, and the muscle-bone-ligament interactions in complex articulations. Building upon this neuromuscular biomechanics paradigm is of immense clinical relevance: it will be instrumental to the development of clinical treatments to preserve and restore manual ability in people suffering from neurological and orthopedic conditions. This understanding will also advance the design and control of robotic hands whose performance lags far behind that of their biological counterparts.     

Adult peripheral nerve disorders: nerve entrapment, repair, transfer, and brachial plexus disorders

LEARNING OBJECTIVES: After reading this article, the participant should be able to: 1. Describe the pathophysiologic bases for nerve injury and how they apply to patient evaluation and management. 2. Recognize the wide variety of injury patterns and associated patient complaints and physical findings associated with peripheral nerve pathology. 3. Evaluate and recommend further tests to aid in defining the diagnosis. 4. Specify treatment options and potential risks and benefits. SUMMARY: Peripheral nerve disorders comprise a gamut of problems, ranging from entrapment neuropathy to direct open traumatic injury and closed brachial plexus injury. The pathophysiology of injury defines the patient's symptoms, examination findings, and treatment options and is critical to accurate diagnosis and treatment. The goals of treatment include management of the often associated pain and improvement of sensory and motor function. Understanding peripheral nerve anatomy is critical to adopting novel nerve transfer procedures, which may provide superior options for a variety of injury patterns.     

SOME NEUROCHEMICAL ASPECTS OF PENTAMETHYL-ENETETRAZOLE CONVULSIVE ACTIVITY IN RAT BRAIN

Abstract— The concentrations of several metabolites, including glucose, glycogen, hexose phosphates, adenine nucleotides, amino acids and some tricarboxylic cycle intermediates were estimated in cerebral tissue of rats killed at various stages of pentamethylenetetrazole convulsions. Prior to and during the seizure there was an increase in glycolytic flux and depletion of energy reserves. An accumulation of alanine concomitant with a decreased citrate level observed before the convulsion indicated that a possible interference of pyruvate entry into the tricarboxylic cycle had occurred. At the tonic extensor phase of the seizure and during post-convulsive sedation a small but significant rise in GABA and an attempt to restore some of the labile constituents to more normal values was apparent. The significance of these results in relation to cerebral metabolic control and possible mechanisms of initiation and arrest of the seizure is discussed.     

The extensor digitorum brevis as a muscle island flap

The use of the extensor digitorum brevis muscle as a local muscle island flap for the coverage of the soft-tissue defects in the region of the lateral malleolus is presented. The anatomy of the muscle, the donor dissection, and the utilization of the extensor digitorum brevis muscle as a local muscle flap in the lower extremity are discussed. This flap was used successfully in a patient with a wound over the lateral malleolus and ankle.     

Early joint and tendon reconstruction for a degloving injury to the dorsum of the hand

Primary insertion of inert material into an open wound to expedite joint and tendon reconstruction can be safely accomplished if the wound is thoroughly debrided and the material is covered with a well-vascularized flap. In this case, metacarpophalangeal mobility and extensor tendon function were largely preserved by early insertion of silicone spacers and rods in the reconstruction of a severe degloving injury to the dorsum of the hand.     

UPJ Obstruction in the Adult Population: Are Crossing Vessels Significant?

Ureteropelvic junction (UPJ) obstruction describes various causes of impaired drainage at the UPJ. Regardless of the cause, the end result is the same: impedance in the normal flow of urine from the renal pelvis into the proximal ureter, resulting in caliectasis and hydronephrosis. This may lead to progressive deterioration of renal function and, thus, often requires intervention to relieve the obstruction and restore the normal flow of urine. Defining the pertinent anatomy, the degree of obstruction, and differential renal function is key to determining whether and when intervention is necessary.     

Regulation of protein metabolism by a physiological concentration of insulin in mouse soleus and extensor digitorum longus muscles. Effects of starvation and scald injury.

1. Although high concentrations of insulin affect both synthesis and degradation of skeletal-muscle protein, it is not known to what extent these effects occur with physiological concentrations. The effects of a physiological concentration of insulin (100 mu units/ml) on muscle protein synthesis, measured with [3H]tyrosine, and on muscle protein degradation, measured by tyrosine release in the presence of cycloheximide, were studied in mouse soleus and extensor digitorum longus muscles in vitro. 2. Insulin significantly stimualated protein synthesis in both muscles, but an inhibition of degradation was seen only in the extensor digitorum longus. 3. Starvation for 24 h decreased the rate of protein synthesis and increased the rate of breakdown in the extensor digitorum longus. Sensitivity to insulin-stimulation of proteins synthesis in the soleus was increased by starvation. 4. ;a 20%-surface-area full-skin-thickness dorsal scald injury produced a fall in total protein content in soleus and extensor digitorum muscles, maximal on the third day after injury. Soleus muscles 2 days after injury showed an impairment of protein synthesis; degradation was unaffected and neither synthesis nor degradation in vitro was significantly affected in the extensor digitorum longus. 5. The advantages and limitations of studies of protein metabolism in vitro are discussed.     

心外膜脂肪组织与心血管疾病的研究进展

心外膜脂肪组织(epicardial adipose tissue,EAT)是一种特殊的具有局部和全身效应的多功能脂肪组织,其解剖位置特殊,代谢和组织学特征明显区别于其他脂肪组织.在生理条件下,EAT具有产热和保护心脏的作用;而在病理状态下,EAT通过分泌多种促炎细胞因子/脂肪因子,参与心血管疾病(cardiovascular disease,CVD)的发生发展.EAT的厚度/体积及其引发的慢性炎症反应与CVD的严重程度呈显著正相关,运动、减轻体重和药物等均可恢复EAT对心血管的保护作用,提示其有望成为CVD诊断、治疗和预后评价的指标.本文通过对EAT的特征、功能、调节机制以及在血管损伤后重构、动脉粥样硬化、高血压病、心律失常、心功能不全等CVD中的作用做一综述,以期为CVD的防治提供新靶点.     

肌电生物治疗联合运动康复在桡神经损伤治疗中的临床应用及疗效评价

目的:探究肌肉电刺激生物疗法联合运动疗法对于治疗桡神经损伤患者的临床疗效及运动恢复效果评价。方法:选择2013年5月至2016年5月我院收治的100例桡神经损伤患者。采用随机数字表法随机分为研究组和对照组各50例。对照组采用常规治疗(营养神经药物+针灸)和运动疗法,研究组在此基础上联合肌电生物治疗。治疗时间均为12周。治疗结束后应用统计学方法对两组患者的治疗有效率、腕伸肌和指总伸肌恢复情况、伸腕角度和伸肘角度以及神经传导速度和波幅等方面进行疗效对比。结果:治疗12周后,研究组治疗有效率66.00%高于对照组的50.00%,差异有统计学意义(P0.05)。研究组肌力恢复至4-5级的比例和表面肌电信号(s EMG)增幅均高于对照组,差异均有统计学意义(P0.05)。经治疗后,研究组伸腕角度和伸肘角度的优良率分别为84.00%、80.00%,明显高于对照组的66.00%、68.00%,差异均有统计学意义(P0.05)。两组患者胫神经运动传导速度(MCV)及波幅的均有改善,但研究组的改善效果明显优于对照组,差异有统计学意义(P0.05)。结论:常规治疗联合肌电生物反馈和运动疗法的治疗方案明显能使得患者受益更多,能更好地恢复患者的患肢运动功能,值得临床推广。     

Estradiol replacement reverses ovariectomy-induced muscle contractile and myosin dysfunction in mature female mice.

Skeletal muscle contractility and myosin function decline following ovariectomy in mature female mice. In the present study we tested the hypothesis that estradiol replacement can reverse those declines. Four-month-old female C57BL/6 mice (n = 69) were ovariectomized (OVX) or sham operated. Some mice were treated immediately with placebo or 17beta-estradiol (OVX + E(2)) while other mice were treated 30 days postsurgery. Thirty or sixty days postsurgery, soleus muscles were assessed in vitro for contractile function and susceptibility to eccentric contraction-induced injury. Myosin structural dynamics was analyzed in extensor digitorum longus (EDL) muscles by electron paramagnetic resonance spectroscopy. Maximal isometric tetanic force was affected by estradiol status (P < 0.001) being approximately 10% less in soleus muscles from OVX compared with sham-operated mice [168 mN (SD 16.7) vs. 180 mN (SD 14.4)] and was restored in OVX + E(2) mice [187 mN (SD 17.6)]. The fraction of strong-binding myosin during contraction was also affected (P = 0.045) and was approximately 15% lower in EDL muscles from OVX compared with OVX + E(2) mice [0.263 (SD 0.034) vs. 0.311 (SD 0.022)]. Plasma estradiol levels were correlated with maximal isometric tetanic force (r = 0.458; P < 0.001) and active stiffness (r = 0.329; P = 0.044), indicating that circulating estradiol influenced muscle and myosin function. Estradiol was not effective in protecting muscle against an acute eccentric contraction-induced injury (P >or= 0.401) but did restore ovariectomy-induced increases in muscle wet mass caused by fluid accumulation. Collectively, estradiol had a beneficial effect on female mouse skeletal muscle.     

Renovascular disease, microcirculation, and the progression of renal injury: role of angiogenesis

Emerging evidence supports the pivotal role of renal microvascular disease as a determinant of tubulo-interstitial and glomerular fibrosis in chronic kidney disease. An intact microcirculation is vital to restore blood flow to the injured tissues, which is a crucial step to achieve a successful repair response. The purpose of this review is to discuss the impact and mechanisms of the functional and structural changes of the renal microvascular network, as well as the role of these changes in the progression and irreversibility of renal injury. Damage of the renal microcirculation and deterioration of the angiogenic response may constitute early steps in the complex pathways involved in progressive renal injury. There is limited but provocative evidence that stimulation of vascular proliferation and repair may stabilize renal function and slow the progression of renal disease. The feasibility of novel potential therapeutic interventions for stabilizing the renal microvasculature is also discussed. Targeted interventions to enhance endogenous renoprotective mechanisms focused on the microcirculation, such as cell-based therapy or the use of angiogenic cytokines have shown promising results in some experimental and clinical settings.     

The extensor assembly in two species of opossum,Philander opossum and Didelphis marsupialis

In considering primate and hominoid phylogeny, the fundamental position assigned to opossums is explained partially by the characteristic morphology of their hands and feet. One of the main functional features of the human hand is the ability to make a stabilized arch of the finger. Because the extensor assembly plays a key role in establishing an arched finger, the extensor systems of the digits of both the hands and feet were studied in two species of opossum, Philander opossum and Didelphis marsupialis. In the foot, two extensor tendons join in each toe to form one tendinous plate, which inserts onto the base of the second phalanx. Lumbricals join this plate along the tibial side, and interosseus insertions are found, although a true interosseus wing is lacking. At the proximal interphalangeal level, a terminal tendon takes its origin from this tendinous plate. This terminal tendon is oval in cross-section and contains elastic structures. Oblique bands arise from this terminal tendon and run proximally along the proximal interphalangeal joint inserting onto the base of the first phalanx. There are elastic structures in the flexor tendon on the dorsal side near its site of insertion. In the hand, the main extensor tendons are arranged differently and the interossei contribute substantially to the extensor assembly. Otherwise, the extensor assembly of the hands and feet are quite similar. The function of the so-called paratendinous intravaginal flexors is discussed as are evolutionary aspects of the extensor assembly.     

Dihydropyridine and ryanodine receptor binding after eccentric contractions in mouse skeletal muscle.

The purpose of this study was to determine whether there are alterations in the dihydropyridine and/or ryanodine receptors that might explain the excitation-contraction uncoupling associated with eccentric contraction-induced skeletal muscle injury. The left anterior crural muscles (i.e., tibialis anterior, extensor digitorum longus, and extensor hallucis longus) of mice were injured in vivo by 150 eccentric contractions. Peak isometric tetanic torque of the anterior crural muscles was reduced approximately 45% immediately and 3 days after the eccentric contractions. Partial restoration of peak isometric tetanic and subtetanic forces of injured extensor digitorum longus muscles by 10 mM caffeine indicated the presence of excitation-contraction uncoupling. Scatchard analysis of [3H]ryanodine binding indicated that the number of ryanodine receptor binding sites was not altered immediately postinjury but decreased 16% 3 days later. Dihydropyridine receptor binding sites increased approximately 20% immediately after and were elevated to the same extent 3 days after the injury protocol. Muscle injury did not alter the sensitivity of either receptor. These data suggest that a loss or altered sensitivity of the dihydropyridine and ryanodine receptors does not contribute to the excitation-contraction uncoupling immediately after contraction-induced muscle injury. We also concluded that the loss in ryanodine receptors 3 days after injury is not the primary cause of excitation-contraction uncoupling at that time.     

Rules to limp by: joint compensation conserves limb function after peripheral nerve injury

Locomotion persists across all manner of internal and external perturbations. The objective of this study was to identify locomotor compensation strategies in rodent models of peripheral nerve injury. We found that hip-to-toe limb length and limb angle was preferentially preserved over individual joint angles after permanent denervation of rat ankle extensor muscles. These findings promote further enquiry into the significance of limb-level function for neuromechanical control of legged locomotion.     

Effect of poly(amido)amine (PAMAM) G4 dendrimer on heart and liver mitochondria in an animal model of diabetes

Diabetes‐induced injury related to hyperglycaemia is associated with impaired function of mitochondria. Regardless of their cytotoxicity, PAMAM [poly(amido)amine] G4 dendrimers lower plasma glucose and suppress long‐term markers of diabetic hyperglycaemia in experimental diabetes. In the present study, we aimed at verifying whether such modulatory effects of PAMAM G4 (0.5 μmol/kg of body weight daily for 60 days) may contribute to improved respiration in heart and liver mitochondria from streptozotocin‐diabetic rats. PAMAM G4 alleviated long‐term markers of hyperglycaemia and reduced blood and tissue lipophilic antioxidants in diabetic animals, but did not restore mitochondrial function. In hearts, but not livers, dendrimers further reduced respiratory function and oxidative phosphorylation. Thus ameliorating effects of PAMAM G4 on glycation and glycoxidation in experimental diabetes are not sufficient to restore the impaired mitochondrial function in diabetes.     

Modulation of stem cell fate in intestinal homeostasis,injury and repair

The mammalian intestinal epithelium constitutes the largest barrier against the external environment and makes flexible responses to various types of stimuli. Epithelial cells are fast-renewed to counteract constant damage and disrupted barrier function to maintain their integrity. The homeostatic repair and regeneration of the intestinal epithelium are governed by the Lgr5⁺ intestinal stem cells (ISCs) located at the base of crypts, which fuel rapid renewal and give rise to the different epithelial cell types. Protracted biological and physicochemical stress may challenge epithelial integrity and the function of ISCs. The field of ISCs is thus of interest for complete mucosal healing, given its relevance to diseases of intestinal injury and inflammation such as inflammatory bowel diseases. Here, we review the current understanding of the signals and mechanisms that control homeostasis and regeneration of the intestinal epithelium. We focus on recent insights into the intrinsic and extrinsic elements involved in the process of intestinal homeostasis, injury, and repair, which fine-tune the balance between self-renewal and cell fate specification in ISCs. Deciphering the regulatory machinery that modulates stem cell fate would aid in the development of novel therapeutics that facilitate mucosal healing and restore epithelial barrier function.