手部肌腱和神经损伤 资料 In-depth

本页面由机器翻译,尚未经临床医生审核。英文版本为权威版本。

您的感受

手部肌腱或神经损伤通常继发于切割伤、挤压伤或导致手指突然向后牵拉的突发外力。疼痛位于损伤部位,常沿手指或拇指的掌侧,或沿神经走行路径分布。当手部进行抓握、挤压或推压动作时,疼痛往往会加剧;当手部处于休息状态时,疼痛则趋于缓解。

当肌腱被切断时,您可能会发现手指无法自主弯曲,尽管他人可以为您将其伸直。弯曲手指以捡起硬币、握住茶杯或转动钥匙会变得困难甚至不可能。当神经被切断时,手部或手指部分区域的感觉会发生改变。您可能会注意到麻木、刺痛或蚁走感,并且在该部位可能无法感知热、冷或尖锐边缘。由于手指无法反馈其接触物体的信息,扣小纽扣、捡起针或摸索口袋中的硬币等精细任务会变得棘手。

某些损伤在夜间或清晨时疼痛更为明显。受刺激的神经在轻叩痛点时可能引发尖锐的、类似电击的感觉,且这种感觉可能随时间推移沿手指进一步蔓延。部分患者会在神经愈合部位形成压痛点,称为神经瘤,触碰或按压时可能引起疼痛。

这些损伤常与手部或手指骨折同时发生,这种组合会增加出现持续性僵硬或无力的风险。手部恢复效果取决于多种因素:切口是清洁伤还是挤压伤、是否伴有骨折、受损的手指或肌腱数量、您的年龄,以及术后接受的手部治疗类型。尽早由手部专科医生就诊能为修复手术提供最佳机会,因此值得及时检查,而不是等待观察其是否自行缓解。

实际发生了什么

您的手部结构如同一台精密的小型机器。它包含27块骨骼,以及数量大致相当的肌腱——这些肌腱是连接肌肉与骨骼的索状结构,在您想要移动手指时拉动它们。神经伴随肌腱走行,负责将指尖的感觉传导至大脑,并将指令向下传递以驱动肌肉工作。

切割伤或挤压伤可能导致肌腱或神经断裂。肌腱由强韧的纤维束构成,一旦切断,两端会相互分离。手指因此失去屈曲力量,这就是为何受伤后手指无法自主弯曲。神经的功能更像一根电缆。当神经被切断时,损伤远端的神经组织会发生退变,该区域的感觉随之消失。

这两种结构都会尝试自我修复,但在狭小的空间内,其修复方式往往引发问题。切断的肌腱在约6至8周内生长出新生组织,但这些新生组织在强度和光滑度上均不及原始组织。在愈合过程中,肌腱可能粘连于包裹它的薄层鞘管,犹如粘性胶带将抽绳固定住。这阻碍了肌腱的滑动,导致即使修复愈合后,手指仍会僵硬。

正在愈合的神经会尝试萌发新的末梢,向指尖方向生长。如果这些新生末梢无法跨越损伤部位,它们可能形成一团纠缠且敏感的结节。这种结节称为神经瘤,也是部分患者出现触痛、触碰时疼痛加剧的原因。神经再生缓慢,且恢复的感觉往往无法完全恢复至伤前水平。

这正是早期修复至关重要的原因。一旦肌腱断端分离或神经断端形成瘢痕,重新吻合的难度将显著增加,手部可能永远无法恢复原有的灵活滑动功能或感觉。

我们如何处理

Mater Private Hospital Rockhampton 的上肢外科医生 Kieran Hirpara 医生会根据您的具体损伤情况制定治疗方案。患者通常由其全科医生(GP)转诊至我们的诊所;如果理疗师建议您就诊,您仍需获得全科医生的转诊,才有资格享受 Medicare(澳大利亚公共医疗保险)报销。在诊所就诊时,我们会采集病史、检查您的手部,并在必要时安排影像学检查。对于新鲜的肌腱或神经切割伤,可能建议立即手术,无需等待。

手部治疗是治疗的重要组成部分,无论是否接受手术。治疗师会为您佩戴支具,将手部固定在安全位置,通过轻柔的活动引导肌腱和神经滑动,防止其粘连,防止手指因挛缩而弯曲,并重新训练已失去感觉的手指。术后遵循的治疗方案是决定手部后期功能恢复效果的关键因素之一。

当神经被切断且两端无法直接缝合时,有多种方法可以桥接缺损。对于短距离缺损,可以使用由胶原蛋白制成的导管引导神经再生跨越缺损区域,该材料具有良好的生物相容性。对于长达 5 厘米的较长缺损,可以使用处理过的供体神经移植。另一种选择是神经转位术,即将功能正常的神经重新路由,以承担受损神经丧失的功能。具体选择哪种方案取决于缺损的大小以及受伤后经过的时间。

对于肌腱,干净的切割伤通常可以直接修复。如果肌腱损伤最初被漏诊,或之前的修复失败,可以使用肌腱移植来桥接缺失部分。如果神经没有恢复的现实可能性,可以进行肌腱转位术,将功能正常的肌腱重新路由,以替代失效肌腱的功能。当尽快恢复工作和日常生活比等待神经再生更为重要时,有时会选择此方案。

有些人会在神经愈合形成神经瘤的部位遗留疼痛点。手术可以松解被瘢痕组织包裹的神经,或将神经末端移位,使其不再卡在敏感的皮肤下方。

在任何手术之前,我们可能会使用扫描进行规划。MRI 可以显示从外部不可见的撕裂肌腱,而超声可以追踪神经的恢复情况。

预期情况

手部肌腱或神经损伤的恢复过程缓慢,且很少呈现线性进展。修复后的肌腱在约6至8周内生长出新的组织,但这些新组织的强度和光滑度均不及原始组织。神经再生的速度远慢于肌腱,且其恢复的感觉往往无法完全达到受伤前的水平。在数周至数月的时间内,您可以预期的是渐进性的变化,而非突然恢复正常。

对于肌腱而言,接受治疗后预后通常较为稳定。大多数修复能够保持完好,但仍有少数失败:约4%的屈肌腱修复会发生断裂,约6%的患者需要接受某种形式的再次手术。瘢痕组织也可能将肌腱粘连固定,这种情况发生在约4%的修复案例中,尽管修复本身已愈合,但仍会导致手指僵硬。如果修复延迟,或手腕处的肌腱需要移植,结果往往远非完美。若对切断的肌腱置之不理,手指将无法自主弯曲,因为肌腱的两端已经分离。

对于神经而言,诚实比乐观更为重要。当修复单根指神经(即手指的感觉神经之一)时,仅有24%的患者能恢复到接近或等同于受伤前水平的感觉。这意味着,即使修复手术做得很好,大多数人仍会在该手指留下一定程度的麻木或感觉异常。时间同样至关重要:等待超过6个月才修复神经,会显著减少能够生长的新神经纤维数量,且在这些月份内,神经纤维需要到达的肌肉末端可能会发生萎缩。较大的神经若发生锐器损伤且修复延迟数天,通常需要进行移植,尽管某些指神经在受伤后两周甚至更长时间仍可修复。

当神经无法恢复时,可以通过肌腱转位术来恢复运动功能,这条途径通常比等待神经再生能让您更快地重返工作和日常生活。无论接受何种治疗,手部治疗都会影响手部后期的功能表现。愈合中的修复部位周围出现一些酸痛感是常见的,通常会在数月内逐渐消退。

何时就医

如果您手部受伤且某根手指无法自主弯曲,或手部在切割伤或挤压伤后出现部分麻木,请前往急诊科。这些损伤具有时间紧迫性:神经若超过6个月未修复,其再生能力将大幅丧失,且在此期间,神经需要到达的肌肉末端可能会萎缩。部分指神经修复在受伤后两周甚至更长时间仍可实施,但就诊越早,保留的治疗选择越多。

如果您发现敲击疼痛点时出现尖锐的、类似电击的感觉,且该感觉随时间沿手指进一步蔓延,或存在触碰时疼痛加剧的压痛点,请寻求专科医生评估。这些症状可能提示存在神经问题,需及时评估。如果您的手部损伤伴随骨折,也请提及这一点,因为这种组合会增加出现持续性僵硬或无力的风险。

如果您有持续不缓解的疼痛、麻木或无力,或受伤的手指出现僵硬或弹响,请咨询您的全科医生(GP)。全科医生可为您转诊至手部专科医生进行评估,并安排相关检查,如神经电生理检查。此类检查通常在受伤后3至4个月进行,以评估神经的恢复情况。

深入探讨

Advanced reading: the deeper science (optional)

本节内容超出了您自身治疗决策所需的范围。手部肌腱和神经修复值得额外阅读,因为手术仅是治疗的一部分,术后数周内的恢复过程对最终结果的影响与修复手术本身同等重要,且相关证据已变得非常具体。

早期活动优于保护

屈肌腱修复术后,存在两种相互竞争的情况:活动手指可能导致修复处断裂;保持静止则会使肌腱与腱鞘发生瘢痕粘连,导致肌腱虽愈合完整但无法滑动,最终形成一根内部肌腱已愈合但手指僵硬的状态。

在 569 例患者中,早期主动活动组的总主动活动度优于早期被动活动组。限定条件与发现本身同样重要:在使用仅 2 股核心缝线 进行修复的主动屈伸亚组中,观察到 更高的断裂风险 [1]。

这正是精确陈述的权衡。早期主动活动能带来更好的最终活动度,但它要求修复强度足以承受这种活动。这就是为什么修复处跨越的缝线股数值得讨论,这并非单纯的技术细节,而是决定能否采用更安全、更优康复方案的关键因素。

相对运动法及其证据的实际适用范围

相对运动夹板将受伤手指固定在与邻近手指略有不同的对位中,从而为修复部位卸载应力,同时允许手部活动。与将手部固定六周相比,其在耐受性方面是一项显著进步。

证据基础并不均衡,准确了解这一点至关重要。目前已有充分证据表明,相对运动法在 V-VI 区伸肌腱修复中是安全的,但对于 IV 区和 VII 区伸肌腱以及屈肌腱修复的证据有限 [2]。

因此,尽管该方案在手背伸肌腱修复中得到了充分支持,但根据现有证据,其在手指屈肌腱修复中的应用尚未得到同等程度的确立。若在此处使用,属于合理的推断,而非已证实的临床实践。

对于神经而言,技术的重要性不如间隙

指神经修复采用了多种技术,包括直接缝合、取自其他部位的自体神经移植、经处理的同种异体神经移植以及人工导管。

在625例修复中,所有可用技术均具有合理的疗效,且当存在间隙时,排除直接修复,自体移植与同种异体移植的疗效相当 [3]。

因此,决定性变量是神经断端能否在无张力状态下对接。如果可以,则进行直接修复。如果不可以,则必须桥接间隙,而目前的证据并不强制要求从患者身体其他部位取神经来完成此操作,这避免了供区损伤及其伴随的麻木区域。

为何恢复期以月计

两种组织的愈合均遵循生物时间表,任何技术手段都无法缩短这一过程。修复后的肌腱在术后三周左右最为脆弱,此时初始的纤维蛋白已被吸收,而新的胶原尚未成熟,这恰恰是手指感觉好转、人们最倾向于使用手指的时期。

神经通过轴突沿残留的神经鞘生长来再生,速度大约为每天一毫米。因此,从手指基部的切断处到指尖需要数月时间,感觉的恢复是渐进且不完整的,通常先表现为令人不适的超敏状态,之后才转变为有用的感觉。这一过程属于预期的恢复过程,而非并发症。

参考文献

[1] Xu H, Huang X, Guo Z, Zhou H, Jin H, Huang X. Outcome of surgical repair and rehabilitation of flexor tendon injuries in zone II of the hand: systematic review and meta-analysis. J Hand Surg Am. 2023;48(4):407.e1-407.e11. https://doi.org/10.1016/j.jhsa.2021.11.013

[2] Shaw AV, Verma Y, Tucker S, Jain A, Furniss D. Relative motion orthoses for early active motion after finger extensor and flexor tendon repairs: a systematic review. J Hand Ther. 2023;36(2):332-46. https://doi.org/10.1016/j.jht.2023.02.011

[3] Herman ZJ, Ilyas AM. Sensory outcomes in digital nerve repair techniques: an updated meta-analysis and systematic review. Hand (N Y). 2019;15(2):157-64. https://doi.org/10.1177/1558944719844346


Evidence & references

This is the clinical evidence summary written for health professionals. It is technical, and it lists the research this page was built from. You do not need to read it to understand your treatment or to make a decision about it.

Overview

Preoperative Assessment and Classification

  • Factors that interfere with the examination of nerves in the hand include other life-threatening or limb-threatening injuries, patient intoxication, anxiety, lack of cooperation, and extensive hand injury [9].
  • If conditions are not satisfactory for a thorough examination during initial evaluation, the hand should be reexamined within a reasonable period to determine the extent of nerve and other injuries [9].
  • A high index of suspicion is necessary in the evaluation of patients with hand injuries [9].
  • Four areas of consideration are important when evaluating a patient with a nerve injury in the hand: type of injury, sensibility evaluation, motor function, and sudomotor function [9].
  • The Seddon classification includes neurapraxia, axonotmesis, and neurotmesis [9].
  • The Sunderland classification includes degrees I through VI, where degree VI is a combination of any of degrees I–V [9].
  • Magnetic resonance neurography (MRA) is reported to provide details regarding nerve anatomic relationships, fascicular pattern, intraneural swelling, and evaluation of downstream muscle injury [9].
  • Customary methods to evaluate damaged sensory nerves include using a sharp pin to assess pain, a cotton-tipped applicator or finger eraser to assess light touch, and the tips of a paper clip or commercially prepared tool to assess two-point discrimination [9].
  • Normal two-point discrimination is usually 6 mm or less [9].
  • Patients with closed injuries or partial injuries to nerves may show spotty appreciation of light touch and pain and have markedly widened two-point discrimination [9].

Surgical Anatomy and Incisions

  • It is of paramount importance to respect and preserve the sensibility of the skin of the fingers and to avoid placing incisions in regions where pressure is commonly applied [40].
  • The palmar cutaneous branch of the median nerve is the sensory nerve most susceptible to iatrogenic injury [40].
  • The diameter of the palmar cutaneous branch of the median nerve is about 0.8 mm [40].
  • The palmar cutaneous branch of the median nerve originates on the radial border of the median nerve 5 to 6 cm above the distal transverse flexion crease of the wrist [40].
  • To avoid the palmar cutaneous branch of the median nerve and its branches, which constitute the most frequent source of palmar neuromas, the forearm incision must be ulnar to the palmaris longus tendon [40].
  • The dorsal branch of the ulnar nerve arises from the medial aspect of the ulnar nerve at an average distance of 6.4 cm from the distal aspect of the head of the ulna [40].
  • The dorsal branch of the ulnar nerve arises from the medial aspect of the ulnar nerve at an average distance of 8.3 cm from the proximal border of the pisiform [40].
  • The terminal sensory branch of the radial nerve becomes superficial about 4 cm proximal to the radiocarpal joint line [40].

Nerve Reconstruction and Transfers

  • Nerve transfers are an option for restoring hand and forearm function in patients with peripheral nerve injuries adversely affecting their ability to function [2].
  • Nerve transfer is favored over nerve grafting in managing high ulnar nerve injuries because of better improvement of motor power and better restoration of grip functions of the hand [5].
  • In lower-type injuries of the brachial plexus, transfer of median nerve branches that innervate the palm of the hand to the ulnar proper digital nerve of the little finger predictably restored protective sensation on the ulnar side of the hand [6].
  • The biomechanical principles, indications, and limitations of tendon transfers, nerve transfers, and combined approaches are compared with particular attention to timing, patient selection, and functional goals [8].
  • Experimental studies and positive reports from large clinical series suggest that new techniques using foreign nerves for reinnervation are worthy of integration into the management of upper brachial plexus injuries [16].
  • Many questions regarding timing, donor morbidity, and comparative efficacy remain unanswered for new techniques using foreign nerves for reinnervation in upper brachial plexus injuries [16].
  • Vascularized ulnar nerve graft technique should be recommended for reconstruction of the median or radial nerves in selected cases [18].
  • Specific nerve transfers are preferred for motor and sensory restoration in high median nerve injury [21].
  • Median nerve repair is mandatory for patients with high median nerve injury who have concomitant pain [21].
  • End-to-side distal anterior interosseous nerve transfer provides significantly better results than a standard more proximal nerve repair in the treatment of proximal ulnar nerve injuries [26].
  • Nerve transfer to the median nerve using parts of the ulnar and radial nerves may offer an alternative option for proximal nerve injuries or for free functioning muscle transplantations [39].

Preservation and Reconstruction

  • The conservation of amputated finger-tips provides the hand surgeon with new possibilities for late reconstruction of an injured digit [3].

Anatomy & Pathophysiology

General Hand Architecture

  • The hand is both an organ designed to obtain information and an organ of execution [20].
  • The hand functions efficiently only if the proximal joints of the limb are stable and yet mobile [20].
  • The hand moves within a large volume of space, with the shoulder being the apex [20].
  • The shoulder is the most mobile joint in the body and allows orientation of the upper limb as required [20].
  • The movements of the clavicle amplify those of the shoulder [20].
  • The elbow, through flexion–extension movements, brings the hand closer to or moves it away from the body [20].
  • Distal to the elbow, there is in effect only one physiological unit [20].
  • The combined movements of the wrist and forearm place the hand in a position for grasping [20].
  • For gripping, the wrist is usually in flexion when close to the trunk and in extension when placed at a distance [20].
  • Forearm rotation (pronation–supination) plays an important role, particularly for bringing food to the mouth [20].
  • The hand’s blood and nerve supplies are continuous with those of the rest of the limb [20].
  • Some of the hand's muscles, the extrinsic muscles, arise in the arm and forearm [20].
  • The open hand, with fingers extended and in contact, forms a balanced graceful oval in its longitudinal axis [20].
  • The proximal “carpometacarpal” half of the hand is flattened, presenting two faces [20].
  • The posterior or dorsal aspect of the hand is convex [20].
  • The anterior, palmar or volar aspect of the hand is concave [20].
  • The distal half of the hand is separated into five digits, which flex toward the palm [20].
  • The digits converge in closing—that is, they flex and adduct—and diverge in opening—that is, they extend and abduct [20].
  • The thumb has a more proximal and lateral position, allowing movement inward and outward from the palm [20].
  • The four fingers are the distal extension of the carpometacarpal part of the hand [20].
  • The hinges of finger movements are not at the bases of the digits, but at the thenar crease and at the transverse distal palmar crease [20].
  • When the digits are fully extended and touching each other, the tips almost describe a regular curve, with the peripheral digits being the shortest [20].
  • When the fingers are extended and separated, the tips of the fingers lie on the circumference of a circle whose center is the head of the third metacarpal [20].
  • The hand consists of 19 bones, 17 articulations, and 19 muscles situated entirely within the hand [20].
  • The hand contains about the same number of tendons activated by the forearm muscles as it has intrinsic muscles [20].
  • The hand requires a stable wrist and at least two sensate digits that can oppose with some power for functional prehension [22].

Osseous Skeleton

  • The skeleton of the hand and wrist consists of 27 bones, of which 19 are long bones [31].
  • The skeleton is divided into five rays, each ray making up a polyarticulated chain comprising the metacarpals and phalanges [31].
  • The base of each metacarpal articulates with the distal row of the carpus [31].
  • The carpus articulates with the skeleton of the forearm through its proximal row [31].
  • The radioulno-carpal articulation has two axes of movement to which is added a third—pronation and supination from the forearm [31].
  • The wrist has three axes of movement, permitting the hand to be positioned in any spatial configuration [31].
  • The radial ray or first ray is the shortest and is made up of only three bones—a metacarpal and two phalanges [31].
  • The first ray continues the external column of the carpus formed by the scaphoid and trapezium [31].
  • The trapezium is clearly angled out in front of the carpal plane so that the first metacarpal makes an angle of about 45 degrees with the second metacarpal in the sagittal plane [31].
  • The thumb metacarpal is the shortest, and the index metacarpal is by far the longest [31].
  • The proximal and middle phalanges of the long and ring fingers are longer than those of the index finger [31].
  • The lengths of the metacarpals vary, with the thumb metacarpal being the shortest, the index finger the longest, and the others decreasing in length from the third to the fifth digits [31].
  • The relative lengths of skeletal segments vary with the movements of opening and closing the fist [31].
  • The digital extremes of each ray converge in flexion either toward the pulp of the thumb for thumb pinch or toward the base of the thenar eminence for power grip [31].
  • The more ulnar the digit, the more obliquely it must deviate as it approaches the palm [31].
  • The two ulnar metacarpals, especially the fifth, have slightly more mobility in flexion–rotation, compensating for their lack of length [31].
  • The convergence of the palmar digits toward the scaphoid tubercle results from the orientation of their distal segments in flexion [31].
  • The deviations of the digits are produced essentially at the level of the metacarpophalangeal and the proximal interphalangeal articulations [31].
  • The skeleton of the hand presents a longitudinal and transverse concavity, giving it the shape of a cup with a palmar concavity when the thumb is placed next to the index finger [31].
  • When the thumb spreads to grasp an object, the cup becomes a gutter whose major oblique axis follows the thumb crease [31].
  • The transverse axis of the palm, which corresponds to the metacarpophalangeal articulations, is not perpendicular to the longitudinal axis [31].
  • The transverse axis is oblique, more distal at the metacarpophalangeal joint of the index finger and more proximal at the fifth metacarpophalangeal joint [31].
  • The transverse axis forms an acute angle of approximately 75 degrees with the longitudinal axis [31].
  • The epiphyseal plates are located at the proximal ends of the phalanges and the first metacarpal [31].
  • The epiphyseal plates are located at the distal ends of the other metacarpals [31].
  • The fixed elements of the hand skeleton include the middle metacarpals [31].
  • The index metacarpal is the most firmly fixed [46].
  • The ring metacarpal is a transitional element to the fifth metacarpal and has about 10 degrees of mobility in flexion and extension [46].
  • The fifth metacarpal is semi-independent; it articulates with the hamate and is restrained on its radial side by its articulation with the base of the fourth metacarpal [46].
  • The fifth metacarpal has a range of flexion–extension of approximately 20 degrees [46].
  • The second to fifth metacarpals are all bound together by various fibrous structures, the most distal of which is the deep transverse intermetacarpal ligament [46].
  • The deep transverse intermetacarpal ligament is better named the interglenoid ligament, because it ties together the anterior “glenoid ligaments” of the metacarpophalangeal articulations, known as the “volar plates” [46].
  • The longitudinal arches are composed of a fixed portion, the carpometacarpal, and a mobile portion, the digits [46].
  • The keystones of the longitudinal arches are the metacarpophalangeal articulations [46].
  • The thick anterior glenoid capsules, the volar plates, prevent hyperextension at the metacarpophalangeal joints [46].
  • The volar plates are interconnected by the transverse interglenoid ligament [46].
  • The stability of the metacarpophalangeal joints is essential to the support of the longitudinal arch as well as of the transverse metacarpal arch [46].
  • The five rays of the hand differ in mobility and independence, with considerable mobility for the thumb, much less for the fifth ray, and even less for the others [46].
  • The index ray has a certain degree of independence at the phalangeal level, owing to the arrangement of its flexor and extensor muscles [46].
  • The metacarpal arch is endowed with a great deal of adaptability because of the mobility of the peripheral metacarpals [46].
  • The peripheral metacarpals form the sides of the cup or the palmar gutter and can deepen the concavity as they approach each other [46].
  • The thumb metacarpal is independent and articulates with the trapezium [46].
  • The middle metacarpals are united to the carpus by the intrinsic interlocking encasement of the bones themselves [46].

Musculature and Tendon Anatomy

  • Control of digital posture requires a complex balance of extrinsic and intrinsic muscle forces [30].
  • Extrinsic muscles have their origin outside of the hand and their insertion on the hand or carpus [30].
  • Intrinsic muscles have both origin and insertion within the hand [30].
  • Extrinsic muscles are either flexors or extensors [30].
  • Intrinsic muscles contribute to both digital flexion and extension [30].
  • The extrinsic extensors run through six different fibroosseous retinacular compartments at the wrist level [30].
  • The first (most radial) compartment contains the abductor pollicis longus and the extensor pollicis brevis [30].
  • The abductor pollicis longus has multiple slips that insert at the base of the thumb metacarpal and radially abducts the thumb [30].
  • The extensor pollicis brevis inserts on the dorsum of the proximal aspect of the proximal phalanx of the thumb and actively extends the metacarpophalangeal joint of the thumb [30].
  • The second extensor compartment contains the extensor carpi radialis longus and the extensor carpi radialis brevis [30].
  • The extensor carpi radialis longus inserts on the index metacarpal, dorsiflexes and radially deviates the wrist [30].
  • The extensor carpi radialis brevis inserts into the base of the middle metacarpal and provides balanced wrist dorsiflexion [30].
  • The third compartment contains the extensor pollicis longus [30].
  • The extensor pollicis longus runs longitudinally down the forearm through the third compartment and turns abruptly radialward about Lister tubercle [30].
  • The extensor pollicis longus provides forceful extension of the thumb interphalangeal joint [30].
  • The oblique course of the extensor pollicis longus tendon provides a substantial adduction component to its pull [30].
  • The fourth extensor compartment contains the extensor indicis proprius lying deep to the four tendons of the extensor digitorum communis [30].
  • The fifth compartment contains the extensor digiti quinti [30].
  • The extensor indicis proprius, extensor digitorum communis, and extensor digiti quinti each have a role in digital extension at the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints of the fingers [30].
  • The principal bony insertion of the extrinsic digital extensors is on the dorsal proximal aspect of the middle phalanx [30].
  • Metacarpophalangeal joint extension is provided by extrinsic extensor force transmitted through the sagittal bands [30].
  • Distal interphalangeal joint extension is achieved through the conjoined lateral bands that are composed of tendinous slips from the extrinsic and intrinsic tendons [30].
  • The extensor indicis proprius inserts on the index finger ulnar to the extensor digitorum communis [30].
  • The extensor digitorum communis inserts on the index, middle, ring, and, in some cases, little fingers [30].
  • The extensor digiti quinti tendon inserts on the little finger ulnar to the extensor digitorum communis insertion [30].
  • The extensor carpi ulnaris tendon runs through the sixth compartment and inserts at the base of the little finger metacarpal [30].
  • The extensor carpi ulnaris provides wrist extension and ulnar deviation [30].
  • The extensor digitorum communis tendons of the middle, ring, and little fingers are tethered together by juncturae tendinum over the dorsum of the hand proximal to the metacarpophalangeal joint [30].
  • The extensor indicis proprius tendon may be recognized at the wrist level as possessing the most distal muscle belly of any of the digital extensor tendons [30].
  • The digital extensor tendons are stabilized over the mid-line of the metacarpophalangeal joint by their attachment to sagittal band fibers [30].
  • The sagittal band fibers insert onto the volar proximal phalanx and onto the lateral borders of the volar plate [30].
  • The sagittal band fibers form a sling that allows proximal extrinsic extensor tension to be transmitted to the proximal phalanx, permitting metacarpophalangeal joint extension without a tendinous insertion onto the proximal phalanx [30].
  • The sagittal bands normally keep the extrinsic extensor as far as possible away from the center of rotation of the metacarpophalangeal joint, thereby giving it the greatest mechanical efficiency [30].
  • With rupture or attenuation of the sagittal band fibers, the extrinsic extensor tendon can sublux to the ulnar side of the metacarpal head causing ulnar deviation of the finger [30].
  • The extrinsic finger flexors are the flexor digitorum profundus and the flexor digitorum superficialis [30].
  • The flexor digitorum profundus inserts on the proximal volar aspect of the distal phalanx [30].
  • The flexor digitorum profundus flexes the distal interphalangeal joint as well as the proximal interphalangeal and metacarpophalangeal joints [30].
  • The flexor digitorum superficialis acts as a flexor of the proximal interphalangeal and metacarpophalangeal joints [30].
  • The extrinsic flexors of the finger consist of the flexor digitorum profundus and the flexor digitorum superficialis [48].
  • The flexor digitorum profundus originates from the proximal ulna and the interosseous membrane [48].
  • In the forearm, the flexor digitorum profundus divides into two muscle groups: the most radial component supplying the index finger and the ulnar component supplying the middle, ring, and little fingers [48].
  • The flexor digitorum profundus and the flexor pollicis longus muscles form the deep compartment of the volar forearm [48].
  • As the flexor digitorum profundus and flexor pollicis longus tendons travel through the carpal tunnel, they occupy the floor of the carpal tunnel [48].
  • The tenosynovial sheath of the flexor pollicis longus is continuous with the radial bursa [48].
  • The tenosynovial sheath to the little finger is continuous with the ulnar digital bursa [48].
  • In some patients, the radial and ulnar bursae communicate, allowing a so-called horseshoe abscess to spread between the thumb and little finger if infection occurs in the flexor tendon sheath of either one of these digits [48].
  • The lumbricals originate from the radial side of the index, middle, ring, and little fingers in the palm [48].
  • The profundus tendon passes through the bifurcation of the flexor digitorum superficialis before inserting into the proximal palmar base of the distal phalanx [48].
  • The innervation of the flexor digitorum profundus of the index and middle fingers is through the anterior interosseous branch of the median nerve [48].
  • The profundus of the ring and little fingers is innervated by the ulnar nerve [48].
  • The flexor digitorum profundus provides digital flexion at both the proximal and distal interphalangeal joints [48].
  • The flexor digitorum superficialis has two heads: The radial head originates from the proximal shaft of the radius, and the humeral ulnar head originates from the medial humeral epicondyle and coronoid process of the ulna [48].
  • Each digit has a corresponding independent superficialis muscle [48].
  • As the superficialis tendons pass through the carpal tunnel, the tendons of the middle and ring fingers are more superficial and central than those of the index and little fingers [48].
  • In the proximal aspect of the finger, the flexor digitorum superficialis tendon bifurcates around the flexor digitorum profundus at the beginning of the A2 pulley [48].
  • The flexor digitorum superficialis tendon slips then reunite distally at the Camper chiasm, with approximately half of the fibers staying on the ipsilateral side and

Classification

  • Nerve injuries are classified based on the severity and extent of the damage [12].
  • Recovery and outcome are dependent on the original classification of the nerve injury [12].
  • The Sunderland classification includes degrees I through VI [9].
  • Seddon Neurapraxia corresponds to Sunderland degree I [9].
  • Seddon Axonotmesis corresponds to Sunderland degrees II, III, and IV [9].
  • Seddon Neurotmesis corresponds to Sunderland degree V [9].
  • Sunderland degree VI is a combination of any of Sunderland degrees I through V [9].

Clinical Presentation

History and Mechanism

  • A careful history is essential to differentiate between neurapraxia and axonotmesis, which can be treated without surgery, and neurotmesis, which requires surgical intervention [10].
  • The mechanism of ulnar nerve injury, excluding compression neuropathy, occurs in order of frequency as laceration, stretch, and contusion [10].
  • Ballistic injuries to the hand are frequently associated with fractures and neurovascular and tendon injuries [4].
  • Severe hand injuries resulting from Samurai sword assaults can cause devastating loss of function for victims [24].
  • Persistent neurological deficits after distal radius fractures should prompt early investigation and consideration for structural nerve injury [14].
  • A triad of multiple metacarpal fractures and/or dislocations of the fingers, severe hand swelling, and clinical evidence of acute median nerve dysfunction has been described [27].
  • Double crush syndrome patients commonly present with peripheral sensorimotor neuropathy, which may include sensory loss, burning or tingling sensation, decreased limb dexterity, limb weakness, or lack of coordination [35].
  • Additional central nervous system symptoms in double crush syndrome may include radiating nerve pain, paresthesia, loss of sensation, hand and upper extremity weakness, hyperreflexia, balance impairment, Lhermitte’s sign, and loss of fine motor control [35].
  • Patients with ulnar artery thrombosis frequently complain of paresthesias in the distribution of the ulnar nerve because the nerve can suffer contusion at the time of injury or be compressed from an aneurysm [62].
  • Patients with ulnar artery thrombosis present with ischemic symptoms in the ulnar digits, with the ring finger involved in nearly half of patients and the middle and little fingers involved in closer to one-third [62].
  • The thumb is rarely ischemic in patients with ulnar artery thrombosis [62].
  • Symptoms of ulnar artery thrombosis may resolve but also may be intermittent after the injury due to ongoing embolization of a clot to the distal digits [62].
  • Patients with ulnar artery thrombosis usually complain of cold intolerance and intermittent color change in the fingers by the time they see a hand surgeon [62].

Physical Examination

  • Factors that interfere with the examination of nerves in the hand include other life-threatening or limb-threatening injuries, patient intoxication, anxiety, lack of cooperation, and extensive injury to the hand [9].
  • If a flexor tendon function deficit is present after a finger laceration, at least one digital nerve probably has been injured as well [9].
  • At least four areas of consideration are important when evaluating a patient with a nerve injury in the hand: type of injury, sensibility evaluation, motor function, and sudomotor function (sweating) [9].
  • Normal two-point discrimination usually is 6 mm or less [9].
  • If the nerve is transected, a patient would not feel light touch, would not appreciate the pin as a sharp stimulus, and would be unable to discriminate between one and two points [9].
  • Vascular condition can be assessed by noting the color of the fingers [57].
  • Some hint of nerve function can be obtained by observing sudomotor function as revealed by sweatiness of the finger pulps [57].
  • The extent and timing of injury are suggested by the degree of swelling and ecchymosis [57].
  • The posture of the digits and the wrist may signal tendon or bone disruption [57].
  • Normally, a cascade of increased digital flexion is noted when ulnar digits are observed next to radial digits [57].
  • Circulation is assessed by capillary refill; when the skin is blanched in the paronychial region, circulation should return within 3 seconds [57].
  • The integrity of the flexor digitorum profundus to each finger is tested by stabilizing the middle phalanx and asking the patient to flex the distal interphalangeal joint [57].
  • The function of the flexor digitorum superficialis of each finger is tested by keeping all fingers except the one to be tested in full extension and asking the patient to flex the finger being evaluated at the proximal interphalangeal joint [57].
  • The function of the flexor pollicis longus is tested by asking the patient to flex the interphalangeal joint of the thumb [57].
  • The function of the extrinsic extensors is tested by asking the patient to extend the metacarpophalangeal joints of the fingers [57].
  • An injury to one digital nerve did not affect the result of a tendon graft in a finger, but when both nerves were injured, the result was compromised [11].
  • In the thumb, there was slight but definite impairment of function when either one or both digital nerves were injured [11].

Diagnostic Modalities

  • Electrodiagnostic testing is critical in determining the level of nerve injury [10].
  • Nerve conduction velocity studies and the results of electromyography (EMG) can be limited in cases of severe axonal loss or early after injury, when neurapraxia cannot be discerned from neurotmesis [10].
  • EMG can also be limited by pain and an inability to identify anatomical variability [10].
  • High-resolution ultrasound imaging can show individual nerve fascicules [10].
  • A change in the hypoechoic signal within the nerve on ultrasound indicates injury [10].
  • Visualization of the epineurium on ultrasound suggests the nerve may be in continuity [10].
  • Magnetic resonance neurography (MRA) is reported to be able to provide details regarding nerve anatomic relationships, fascicular pattern, intraneural swelling, and evaluation of downstream muscle injury [9].
  • A closed partial rupture of a common digital nerve in the palm requiring MRI and surgical exploration for diagnosis has been described [9].
  • Such injuries are likely to be missed in casualty because of extensive soft tissue swelling, the apparent normal appearance of anteroposterior X-rays, and the technical difficulty in testing the motor branch of the ulnar nerve in the presence of pain [38].
  • There is no clear consensus on what qualifies the diagnosis of double crush syndrome [35].
  • There is currently no singular test to simultaneously determine central and peripheral nerve compression [35].
  • Nerve conduction studies may potentially help to find multiple lesions on the same nerve, but there may still be overlap in determining lesion type which makes determining whether there are 2 distinct crush injuries challenging [35].
  • Misdiagnosis of double crush syndrome is common given the extensive number of risk factors [35].
  • The presence of an audible Doppler arterial signal in one of the wrist’s vessels is not an indication of adequate nutritional flow to the hand [51].
  • A digital-brachial index value below 0.7 designates a significant occlusive problem somewhere in the forearm or hand [51].
  • A prolonged rewarming response in cold stress testing is often seen in women and can be diagnostic of Raynaud’s [51].
  • Smokers often have a delayed rewarming response in cold stress testing [51].

Classification and Prognosis

  • Nerve injuries are classified based on the severity and extent of the damage, with recovery and outcome dependent on the original classification [12].
  • Rapid intervention generally improves outcome; however, prolonged denervation of the nerve segments can lead to low recovery rates and to other disabilities [12].
  • Traumatic neurapraxia in digital nerve injuries of the hand is not uncommon and has a favourable prognosis [36].
  • At a mean final follow-up of 7 months, full recovery of median nerve function was seen in all patients with the triad of multiple metacarpal fractures/dislocations, severe hand swelling, and acute median nerve dysfunction [27].
  • Rates of median nerve symptoms were high and resolved in most cases (92%) after reduction of perilunate dislocation [17].

Investigations

Diagnostic Modalities and Limitations

  • Electrodiagnostic testing is critical in determining the level of ulnar nerve injury [10].
  • Nerve conduction velocity studies and electromyography (EMG) results can be limited in cases of severe axonal loss or early after injury when neurapraxia cannot be discerned from neurotmesis [10].
  • EMG can be limited by pain and an inability to identify anatomical variability [10].
  • High-resolution ultrasound (US) imaging can show individual nerve fascicules [10].
  • US imaging can identify a change in the hypoechoic signal within the nerve to indicate injury [10].
  • US imaging can visualize the epineurium to suggest whether the nerve is in continuity [10].
  • Evaluation based only on photographs taken in the emergency department is insufficient for the detection of neurovascular bundle injuries, tendon ruptures, and fractures [86].

Clinical Assessment and History

  • A careful history is essential in cases of blunt trauma to differentiate between neurapraxia and axonotmesis (which can be treated without surgery) and neurotmesis (which requires surgical intervention) [10].
  • The mechanism of ulnar nerve injury, excluding compression neuropathy, includes laceration, stretch, and contusion in order of frequency [10].
  • Ulnar nerve injuries are likely to be missed in casualty due to extensive soft tissue swelling, the apparent normal appearance of anteroposterior X-rays, and the technical difficulty in testing the motor branch of the ulnar nerve in the presence of pain [38].

Functional Requirements

Treatment

Nerve Repair and Grafting

  • Rapid intervention for peripheral nerve injuries generally improves outcomes, whereas prolonged denervation of nerve segments can lead to low recovery rates and other disabilities [12].
  • Nerve transfer is favored over nerve grafting for high ulnar nerve injuries due to better improvement of motor power and better restoration of grip functions [5].
  • Distal nerve transfers for high ulnar nerve injuries allow for a shorter reinnervation period and improved ulnar intrinsic recovery [25].
  • End-to-side distal anterior interosseous nerve transfer for proximal ulnar nerve injuries provides significantly better results than a standard more proximal nerve repair [26].
  • Supercharged end-to-side transfers exhibit a role in treating high ulnar nerve damage by supplying intrinsic muscles and allowing for proximal nerve regeneration [69].
  • Vascularized ulnar nerve grafts are recommended for the reconstruction of median or radial nerves in selected cases involving large defects after severe trauma [18].
  • Nerve grafts bridging the thenar branch of the median nerve to the ulnar nerve may support ulnar nerve regeneration and help prevent intrinsic muscles from irreversible atrophy, though the procedure is preliminary and requires validation by future clinical data [72].
  • In high median nerve injuries, median nerve repair is mandatory for patients with concomitant pain [21].
  • If a patient with a high median nerve injury requires a nerve graft, especially if done late or under unfavorable conditions such as a long graft or poor bed, useful extrinsic functional recovery is unlikely [34].
  • Revision nerve reconstruction is typically considered only if a "red flag" has been identified or if definite clinical failure has been confirmed via EMG and sensory mapping before the development of irreversible denervation atrophy [23].
  • Reexploration for revision nerve surgery is rarely performed before 3 to 4 months post-repair to allow enough axonal growth to be detectable using operative nerve-to-nerve conduction studies [23].
  • Neurolysis and wrapping of the repair can be helpful when functional recovery is hindered by neuropathic pain, though this strategy is unpredictable and carries a potential for iatrogenic deterioration [23].
  • Prolonged expectant observation and medical management is preferred in most situations for revision nerve surgery [23].
  • Rates of median nerve symptoms were high in perilunate dislocations but resolved in most cases (92%) after reduction [17].

Nerve Transfers

  • Transfer of the superficial radial or dorsal cutaneous branch of the ulnar nerve, or both, produced successful restoration of innervation of the thumb and index and long fingers in experimental sensory reinnervation studies [13].
  • New techniques using foreign nerves for reinnervation are worthy of integration into the management of upper brachial plexus injuries, though many questions regarding timing, donor morbidity, and comparative efficacy remain unanswered [16].
  • Nerve transfer through the pronator teres motor branch can be suggested in cases where the hand is partially involved to allow patients to regain or strengthen fingers flexion [28].
  • In patients with complete pan-plexal injuries, intact extraplexal nerves (spinal accessory, intercostal, C3 and C4 nerves) can be transferred and coapted to the distal peripheral nerve of the brachial plexus as a method for reinnervation of critical sensory or motor nerves [53].
  • For complete pan-plexus injuries, a single-stage gracilis free functioning muscle transfer (FFMT) is used for both elbow flexion and finger flexion when hand reinnervation is attempted [53].
  • Sensation in the median nerve distribution of the hand in pan-plexus injuries can be provided by the transfer of sensory branches of the intercostal nerves to the lateral cord contribution of the median nerve [53].
  • Secondary surgeries to provide stability to the hand and assist in rudimentary grasp for pan-plexus injuries are performed between 4 and 6 months after the index brachial plexus reconstruction [53].

Tendon Transfers and Reconstruction

  • In high median nerve injuries where a nerve graft is required or recovery is unlikely, early extrinsic end-to-side transfers and/or a side-to-side transfer of the index and conjoined profundus tendons should be considered [34].
  • All intrinsic and extrinsic transfers for high median nerve palsy can be performed at the same time [34].
  • The author prefers EIP transfer if an opposition transfer is indicated for high median nerve palsy [34].
  • The BR transfer is used for restoration of thumb flexion, especially for conditions in which there is relative sensory sparing, and an end-to-side attachment is used unless there is no prospect of later reinnervation [34].
  • The author prefers to join the index and the common (middle, ring, and little) profundi tendons in a side-to-side fashion rather than performing an ECRL transfer to restore index finger flexion, as the hand condition is usually too poor to benefit from an ECRL transfer especially if there is a marked sensory deficit [34].
  • Opponensplasty is typically not beneficial in high median nerve palsy because worthwhile sensory recovery is so unlikely in these cases for adults [34].
  • The goal of any repair in high median nerve palsy is to create the best possible "helper" hand, with precision function assumed by the other hand [34].
  • A reliable tendon prosthesis inserted as one stage in tendon reconstruction is the additional step needed to improve the results of flexor-tendon reconstructive surgery in hands with severe damage [32].
  • In the setting of chronic flexor or extensor tendon injuries of the hand and wrist, one- or two-stage tendon reconstruction techniques should be used instead of tendon repair [50].
  • Wide-awake analgesia allows for intraoperative assessment of flexor or extensor tendon repair/reconstruction and is a safe and cost-effective alternative to intravenous sedation or general anesthesia [50].
  • The management and treatment of complex mutilated upper extremity injuries often can be challenging and at times seemingly formidable [83].

Non-Operative Management and Rehabilitation

  • Early nonsurgical management for up to 6 months in adults and 9 months in children has expanded from closed humeral shaft fractures to include operative fractures that do not require nerve exposure, secondary palsies, and distal third humerus fractures for radial nerve injuries [41].
  • Nonoperative management of the hand while waiting for radial nerve function recovery involves maintenance of full passive range of motion in all joints of the wrist and hand and prevention of contractures, including contracture of the thumb–index web [52].
  • Patients with radial nerve palsy must be taught very soon after the original nerve injury how to perform an appropriate exercise program to keep the joints supple [52].
  • An "off-the-shelf" inconspicuous $10 cock-up wrist splint stabilizes the wrist and restores adequate, and often remarkably good, function without interfering with clothing for patients with radial nerve palsy [52].
  • If a wrist splint is worn only during the day for radial nerve palsy, a splint to hold the wrist and fingers in extension is recommended at night to prevent loss of fiber length of the flexor muscles [52].
  • Clinical outcomes indicate that remote and in-person hand therapy provide similar results for patients with flexor tendon repairs in zones 1 and 2 [55].
  • Patient understanding of nerve transfer procedures is important to ensure initial treatment strategies are correctly implemented, including providing realistic expectations regarding return of function and timing [58].
  • In some cases, patients are instructed preoperatively in motor retraining exercises by utilizing the contralateral arm and normal movement patterns for nerve transfers [58].
  • Early perioperative care for nerve transfers is directed toward protection of the nerve coaptation site, edema, proximal and distal joint range of motion, and pain control [58].
  • Nerve transfers are performed without tension at the coaptation site [58].
  • The nerve transfer coaptation is typically protected for 7–10 days, initially with a bulky dressing for 2–3 days following surgery [58].
  • Tendinopathies of the flexor and extensor tendons of the hand and wrist are common conditions that may be managed conservatively with immobilization, NSAIDs, therapy, and corticosteroid injections [50].
  • Surgical treatment for tendinopathies of the hand and wrist typically involves release of the associated tendon sheath [50].

Complications

Neuroma Formation

  • Painful neuromas can form following digital nerve injury and may be more disabling than the impairment of sensation [42].
  • In a series of 93 digital nerves repaired by direct epineural suture, 2% developed painful neuromas [42].

Sensory Deficits and Recovery Limitations

  • Sensation does not recover to normal in adult patients following digital nerve repair [42].
  • Mean two-point discrimination was 10.6 mm compared with 4.4 mm on the contralateral side in a long-term outcome study of 93 digital nerves repaired by direct epineural suture [42].
  • Useful recovery of sensation (MRC grade S3 or S4) was achieved in 79.5% of nerves in a series of 254 completely divided digital nerves [42].
  • Sensory recovery after a high median nerve repair in adults is always poor and is even worse if a nerve graft is required [34].
  • Return of two-point discrimination is rare following median and ulnar nerve repair [42].
  • The more severe the sensory deficit, the less likely the patient is to benefit from reconstructive surgery for low median nerve palsy [71].

Motor and Functional Complications

  • When both digital nerves are injured in a finger, the result of a tendon graft is compromised [11].
  • In the thumb, there is slight but definite impairment of function when either one or both digital nerves are injured [11].
  • Overall control of muscle function is compromised by sensory impairment following median nerve repair [42].
  • Nerve repair hardly ever restores lost opposition in high median nerve palsy [34].
  • Prolonged denervation of nerve segments can lead to low recovery rates and other disabilities [12].
  • An adduction contracture is a strong tendency in the presence of mangling or crushing injuries to the hand [68].

Diagnostic and Assessment Challenges

  • Digital nerve injuries are frequently overlooked during the initial or preliminary examination of hand injuries [9].
  • It is difficult to evaluate the extent of nerve injury in the hand due to factors such as life-threatening injuries, patient intoxication, anxiety, or lack of cooperation [9].
  • Electrodiagnostic testing results can be limited in cases of severe axonal loss or early after injury when neurapraxia cannot be discerned from neurotmesis [10].
  • The outcome of digital nerve repair is difficult to assess, particularly if only one nerve to a finger has been injured [42].

Revision and Secondary Surgery Complications

  • Neurolysis and wrapping of the repair for neuropathic pain is unpredictable at best and carries a potential for iatrogenic deterioration [23].
  • Unrealistic expectations and secondary gain are practically predictive of failure in revision nerve surgery [23].

Specific Injury Complications

  • Persistent neurological deficits after distal radius fractures can result in ulnar neuroma-in-continuity [14].
  • A flexor tendon function deficit after a finger laceration indicates that at least one digital nerve probably has been injured as well [9].

Recovery

Nerve Injury Outcomes and Prognosis

  • In a series of 93 digital nerves repaired by direct epineural suture, mean two-point discrimination was 10.6 mm compared with 4.4 mm on the contralateral side [42].
  • Only 2% of patients in a series of 93 digital nerve repairs developed painful neuromas [42].
  • Useful recovery (MRC grade S3 or S4) was achieved in 79.5% of nerves in a long-term study of 254 completely divided digital nerves [42].
  • 100% of patients under age 15 years regained useful sensation following digital nerve repair [42].
  • 26% of patients over age 40 years regained useful sensation following digital nerve repair [42].
  • Useful recovery was achieved in only 15% of nerves that required a graft over 50 mm in length [42].
  • Outcomes for median and ulnar nerve repairs are better for primary compared to delayed repair [42].
  • In a series of 584 median and ulnar nerve repairs, 33% gained a good result, 50% fair, 10% poor, and 7% bad [42].
  • 71% of patients below age 10 years achieved good results in median and ulnar nerve repairs [42].
  • 58% of patients aged 11 to 15 years achieved good results in median and ulnar nerve repairs [42].
  • Recovery of thenar muscles is likely after median nerve repair, but overall control of muscle function is compromised by sensory impairment [42].
  • Finger abduction and thumb adduction are more likely to show recovery than finger adduction following ulnar nerve repair [42].
  • Rates of median nerve symptoms following perilunate dislocation were high and resolved in 92% of cases after reduction [17].
  • Rapid intervention generally improves outcome in peripheral nerve injury, whereas prolonged denervation can lead to low recovery rates and other disabilities [12].

Sensory Restoration and Reinnervation

  • Transfer of the superficial radial or dorsal cutaneous branch of the ulnar nerve, or both, produced successful restoration of innervation of the thumb and index and long fingers in experimental monkey models [13].
  • Nerve transfer is favored over nerve grafting in managing high ulnar nerve injuries because of better improvement of motor power and better restoration of grip functions [5].
  • New techniques using foreign nerves for reinnervation are worthy of integration into the management of upper brachial plexus injuries, though questions regarding timing, donor morbidity, and comparative efficacy remain unanswered [16].
  • Sensibility in a neurovascular island graft is never normal after transfer [75].
  • More than half of patients have persistently hyperesthetic skin following neurovascular island graft transfer [75].
  • All patients lack precise sensory reorientation following neurovascular island graft transfer [75].
  • Reorientation seems to improve with time and with use of the part following neurovascular island graft transfer [75].

Combined Tendon and Nerve Injury Outcomes

  • An injury to one digital nerve did not affect the result of a tendon graft in a finger [11].
  • When both digital nerves were injured, the result of a tendon graft in a finger was compromised [11].
  • In the thumb, there was slight but definite impairment of function when either one or both nerves were injured during tendon grafting [11].
  • Flexor tendon repair was followed by good function in a case of simultaneous dislocation of both interphalangeal joints and flexor tendon tear [73].

Functional Requirements and Reconstruction

  • None of the procedures (Zancolli Lasso versus Modified Stiles-Bunnell) is superior to the other statistically in terms of improvement in grip strength, improvement in active ROM of MCPJs, claw correction, or improvement in overall patient hand functions [19].

Key Evidence

  • [L4] Nerve transfers are an option for restoring hand and forearm function in patients with peripheral nerve injuries adversely affecting their ability to function. [2] (10.2106/jbjs.rvw.24.00150)
  • [L4] The conservation of these finger-tips provides the hand surgeon with new possibilities for late reconstruction of an injured digit. [3] (10.1016/s0020-1383(73)80022-1)
  • [L4] Ballistic injuries to the hand are frequently associated with fractures and neurovascular and tendon injuries. [4] (10.1177/15589447221092111)
  • [L4] Nerve transfer is favored over nerve grafting in managing high ulnar nerve injuries because of better improvement of motor power and better restoration of grip functions of the hand. [5] (10.1016/j.jhsa.2017.01.027)
  • [L4] In lower-type injuries of the brachial plexus, transfer of median nerve branches that innervate the palm of the hand to the ulnar proper digital nerve of the little finger predictably restored protective sensation on the ulnar side of the hand. [6] (10.1016/j.jhsa.2012.02.047)
  • [L5] The biomechanical principles, indications and limitations of tendon transfers, nerve transfers and combined approaches are compared, with particular attention to timing, patient selection, and functional goals. [8] (10.1177/17531934261416300)
  • [L5] [10] (10.1016/j.jhsa.2014.04.038)
  • [L4] [12] (10.1177/17531934241240867)
  • [L5] Transfer of the superficial radial or dorsal cutaneous branch of the ulnar nerve, or both, produced successful restoration of innervation of the thumb and index and long fingers. [13] (10.2106/00004623-197759030-00016)
  • [L5] Persistent neurological deficits after distal radius fractures should prompt early investigation and consideration for structural nerve injury. [14] (10.1016/j.jhsg.2026.101074)
  • [L5] Experimental studies and positive reports from large clinical series suggest that new techniques using foreign nerves for reinnervation are worthy of integration into the management of upper brachial plexus injuries, though many questions regarding timing, donor morbidity, and comparative efficacy remain unanswered. [16] (10.1054/jhsb.2000.0460)
  • [L4] Rates of median nerve symptoms were high and resolved in most cases (92%) after reduction. [17] (10.1177/15589447251317236)
  • [L4] This technique should be recommended for reconstruction of the median or radial nerves in selected cases. [18] (10.1016/j.jhsa.2005.03.017)
  • [L2] None of the procedures is superior to the other statistically in terms of improvement in grip strength, improvement in active ROM of MCPJs, claw correction, or improvement in overall patient hand functions, in the intermediate follow-up duration. [19] (10.1177/15589447251364568)
  • [L4] The authors prefer specific nerve transfers for motor and sensory restoration, noting that median nerve repair is mandatory for patients with concomitant pain. [21] (10.1016/j.hcl.2015.12.008)
  • [L5] The hand requires a stable wrist and at least two sensate digits that can oppose with some power for functional prehension. [22] (10.1016/s0749-0712(02)00130-0)
  • [L4] This case series demonstrates the extent and severity of hand injuries that can be caused by sword assaults with devastating loss of function for the victims. [24] (10.1177/1753193410381576)
  • [L5] Distal nerve transfers for the treatment of high ulnar nerve injuries allow for a shorter reinnervation period and improved ulnar intrinsic recovery, which is critical to function of the hand. [25] (10.1016/j.hcl.2015.12.009)
  • [L4] It provides significantly better results than a standard more proximal nerve repair. [26] (10.1016/s0363-5023(11)60008-7)
  • [L4] At a mean final follow-up of 7 months, full recovery of median nerve function was seen in all patients, and all patients were able to return to work. [27] (10.1177/1753193408087105)
  • [L5] This specific procedure can be suggested in cases where the hand is partially involved to allow patients to regain or strengthen fingers flexion. [28] (10.1016/j.jhsg.2025.100844)
  • [L4] The authors conclude that a reliable tendon prosthesis inserted as one stage in tendon reconstruction is the additional step needed to improve the results of flexor-tendon reconstructive surgery in hands with severe damage. [32] (10.2106/00004623-197153050-00001)
  • [Paper] [35] (10.1177/15589447251352122)
  • [L4] Traumatic neurapraxia in digital nerve injuries of the hand is not uncommon and has a favourable prognosis. [36] (10.1007/s00402-007-0299-6)
  • [L4] Such injuries are likely to be missed in casualty because of the extensive soft tissue swelling, the apparent normal appearance of anteroposterior X-rays and the technical difficulty in testing the motor branch of the ulnar nerve in the presence of pain. [38] (10.1016/s0020-1383(96)00207-0)
  • [L5] Clinically, this technique may offer an alternative option for proximal nerve injuries or for free functioning muscle transplantations. [39] (10.1054/jhsb.2000.0389)
  • [L5] Early nonsurgical management for up to 6 months in adults and 9 months in children has expanded from closed humeral shaft fractures to include operative fractures that do not require nerve exposure, secondary palsies, and distal third humerus fractures. [41] (10.5435/jaaos-d-17-00325)
  • [L3] Clinical outcomes indicate that remote and in-person hand therapy provide similar results for patients with flexor tendon repairs in zones 1 and 2. [55] (10.1177/15589447251339498)
  • [L5] [58] (10.1016/j.jht.2013.12.007)
  • [L4] SETS exhibit a remarkable role in the treatment of high ulnar nerve damage by supplying intrinsic muscles and allowing for proximal nerve regeneration. [69] (10.1186/s12891-024-07650-4)
  • [L4] The thenar branch of the median nerve may support ulnar nerve regeneration and help prevent intrinsic muscles from irreversible atrophy, but the report is preliminary and the procedure should be validated by future clinical data. [72] (10.1177/1753193416675069)
  • [L5] Flexor tendon repair was followed by good function. [73] (10.1016/s0020-1383(97)00202-7)
  • [L5] The management and treatment of complex mutilated upper extremity injuries often can be challenging and at times seemingly formidable. [83] (10.1016/s0749-0712(02)00143-9)
  • [L4] Similarly, evaluation based only on the photograph was insufficient for the detection of neurovascular bundle injuries, tendon ruptures, and fractures. [86] (10.1016/j.jhsa.2024.07.009)

References

[2] Review of Outcomes After Peripheral Nerve Transfers for Motor Nerve Injury in the Upper Extremity. JBJS Reviews. 2024. DOI: 10.2106/jbjs.rvw.24.00150

[3] Preservation of amputated finger-tips. Injury. 1973. DOI: 10.1016/s0020-1383(73)80022-1

[4] Outcomes in Ballistic Injuries to the Hand: Fractures and Nerve/Tendon Damage as Predictors of Poor Outcomes. HAND. 2022. DOI: 10.1177/15589447221092111

[5] Nerve Transfer Versus Nerve Graft for Reconstruction of High Ulnar Nerve Injuries. The Journal of Hand Surgery. 2017. DOI: 10.1016/j.jhsa.2017.01.027

[6] Distal Sensory Nerve Transfers in Lower-Type Injuries of the Brachial Plexus. The Journal of Hand Surgery. 2012. DOI: 10.1016/j.jhsa.2012.02.047

[8] Tendon versus nerve transfers – balancing hand function in upper extremity high nerve injuries. Journal of Hand Surgery (European Volume). 2026. DOI: 10.1177/17531934261416300

[9] Campbell S Operative Orthopaedics 4 Volume Set. NERVE INJURIES AT THE LEVEL OF THE HAND AND WRIST > EVALUATION.

[10] Management of Ulnar Nerve Injuries. The Journal of Hand Surgery. 2015. DOI: 10.1016/j.jhsa.2014.04.038

[11] Flexor-Tendon Grafts in the Fingers and Thumb: A STUDY OF FACTORS INFLUENCING RESULTS IN 1000 CASES.. The Journal of Bone and Joint Surgery. American Volume. 1971.

[12] Timing of surgery in peripheral nerve injury of the upper extremity. Journal of Hand Surgery (European Volume). 2024. DOI: 10.1177/17531934241240867

[13] Experimental sensory reinnervation of the median nerve by nerve transfer in monkeys. The Journal of Bone & Joint Surgery. 1977. DOI: 10.2106/00004623-197759030-00016

[14] Ulnar Neuroma-in-Continuity Following Distal Radius Fracture: A Rare Complication Requiring Reconstruction with Nerve Allograft and Dynamic Tendon Transfer. Journal of Hand Surgery Global Online. 2026. DOI: 10.1016/j.jhsg.2026.101074

[16] Avulsion Injuries to the Brachial Plexus and the Value of Motor Reinnervation by Ipsilateral Nerve Transfer. Journal of Hand Surgery. 2000. DOI: 10.1054/jhsb.2000.0460

[17] Perilunate Dislocation Reduction Technique and Results. HAND. 2025. DOI: 10.1177/15589447251317236

[18] Vascularized Ulnar Nerve Graft for Reconstruction of a Large Defect of the Median or Radial Nerves After Severe Trauma of the Upper Extremity. The Journal of Hand Surgery. 2005. DOI: 10.1016/j.jhsa.2005.03.017

[19] Functional Outcomes of Zancolli Lasso Versus Modified Stiles-Bunnell Techniques for Post-Leprosy Ulnar Claw Hand Correction: A Prospective Randomized Comparative Study. HAND. 2025. DOI: 10.1177/15589447251364568

[20] Exam Of The Hand Wrist 2Ed. INTRODUCTION.

[21] High Median Nerve Injury. Hand Clinics. 2016. DOI: 10.1016/j.hcl.2015.12.008

[22] Biomechanics and hand trauma: what you need. Hand Clinics. 2003. DOI: 10.1016/s0749-0712(02)00130-0

[23] Green S Operative Hand Surgery. Technique: Target Muscle Reinnervation > AUTHOR'S PREFERRED METHOD OF TREATMENT: REVISION SURGERY.

[24] Severe hand injuries resulting from Samurai sword assaults: a Dublin case series. Journal of Hand Surgery (European Volume). 2010. DOI: 10.1177/1753193410381576

[25] High Ulnar Nerve Injuries. Hand Clinics. 2016. DOI: 10.1016/j.hcl.2015.12.009

[26] End-to-side Distal Anterior Interosseous Nerve Transfer in Treatment of Proximal Ulnar Nerve Injuries. The Journal of Hand Surgery. 2011. DOI: 10.1016/s0363-5023(11)60008-7

[27] The Triad of Multiple Metacarpal Fractures and/or Dislocations of the Fingers, Severe Hand Swelling and Clinical Evidence of Acute Median Nerve Dysfunction. Journal of Hand Surgery (European Volume). 2008. DOI: 10.1177/1753193408087105

[28] Nerve Transfer for Restoration of Ulnar Fingers Flexion Through Pronator Teres Motor Branch: A Cadaveric Feasibility Study. Journal of Hand Surgery Global Online. 2026. DOI: 10.1016/j.jhsg.2025.100844

[30] A Lange Medical Book Current Diagnosis Treatment In Orthopedics Fifth Edition. 9Hand Surgery > Image DISORDERS OF THE MUSCULATURE OF THE HAND.

[31] Exam Of The Hand Wrist 2Ed. 1.1 SKELETON OF THE HAND > The osseous skeleton.

[32] Flexor-Tendon Reconstruction in Severely Damaged Hands. The Journal of Bone & Joint Surgery. 1971. DOI: 10.2106/00004623-197153050-00001

[34] Green S Operative Hand Surgery. Tendon Transfers for Median, Radial, and Ulnar Nerve Palsy > ECRL-to-Index Profundus Transfer > High Median Nerve Palsy Summary.

[35] Double Crush Syndrome: A Review of the Literature. HAND. 2025. DOI: 10.1177/15589447251352122

[36] Clinical and user-friendly classification of traumatic digital nerve injuries of hand. Archives of Orthopaedic and Trauma Surgery. 2007. DOI: 10.1007/s00402-007-0299-6

[38] Carpometacarpal dislocation producing transient motor neurapraxia of the ulnar nerve. Injury. 1997. DOI: 10.1016/s0020-1383(96)00207-0

[39] Nerve Transfer to the Median Nerve Using Parts of the Ulnar and Radial Nerves in the Rabbit – Effects on Motor Recovery of the Median Nerve and Donor Nerve Morbidity. Journal of Hand Surgery. 2000. DOI: 10.1054/jhsb.2000.0389

[40] Exam Of The Hand Wrist 2Ed. Skin incisions > Sensation.

[41] Updates on and Controversies Related to Management of Radial Nerve Injuries. Journal of the American Academy of Orthopaedic Surgeons. 2019. DOI: 10.5435/jaaos-d-17-00325

[42] Rockwood And Green S Fractures In Adults. 19: Principles of Nerve Injuries and Their Management > Open Injuries to the Hand and Wrist.

[46] Exam Of The Hand Wrist 2Ed. The arches of the hand > The metacarpal arch.

[48] A Lange Medical Book Current Diagnosis Treatment In Orthopedics Fifth Edition. 9Hand Surgery > FLEXOR TENDON INJURY.

[50] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Tendon Injuries and Tendinopathies of the Hand and Wrist > Summary.

[51] Green S Operative Hand Surgery. EVALUATION.

[52] Green S Operative Hand Surgery. Tendon Transfers for Median, Radial, and Ulnar Nerve Palsy > Nonoperative Treatment.

[53] Green S Operative Hand Surgery. Intraoperative Decisions and Priorities of Repair > Pan-Plexal Injury.

[55] Telerehabilitation After Zone 1 and 2 Flexor Tendon Repairs: Comparison With In-Person Therapy. HAND. 2025. DOI: 10.1177/15589447251339498

[57] A Lange Medical Book Current Diagnosis Treatment In Orthopedics Fifth Edition. 9Hand Surgery > DIAGNOSIS OF DISORDERS OF THE HAND.

[58] Advances in nerve transfer surgery. Journal of Hand Therapy. 2014. DOI: 10.1016/j.jht.2013.12.007

[62] Green S Operative Hand Surgery. Complications > Closed Arterial Trauma.

[68] Green S Operative Hand Surgery. EVOLUTION IN THE TREATMENT OF MANGLING INJURIES > CASE STUDY 43.3 Partial Hand Amputation.

[69] Supercharged end-to-side anterior interosseous nerve transfer to restore intrinsic function in high ulnar nerve injury: a prospective cohort study. BMC Musculoskeletal Disorders. 2024. DOI: 10.1186/s12891-024-07650-4

[71] Green S Operative Hand Surgery. Tendon Transfers for Median, Radial, and Ulnar Nerve Palsy > Expectations and Patient Counseling for Low Median Nerve Palsy.

[72] Nerve grafts bridging the thenar branch of the median nerve to the ulnar nerve to enhance nerve recovery: a report of three cases. Journal of Hand Surgery (European Volume). 2016. DOI: 10.1177/1753193416675069

[73] Simultaneous dislocation of both interphalangeal joints and flexor tendon tear in a finger. Injury. 1998. DOI: 10.1016/s0020-1383(97)00202-7

[75] Campbell S Operative Orthopaedics 4 Volume Set. NERVE INJURIES AT THE LEVEL OF THE HAND AND WRIST > NEUROVASCULAR ISLAND GRAFTS.

[83] Use of “spare parts” in mutilated upper extremity injuries. Hand Clinics. 2003. DOI: 10.1016/s0749-0712(02)00143-9

[86] Evaluation of Injured Structures and Circulation of Fingers From Photos Taken in the Emergency Department After Hand Injury. The Journal of Hand Surgery. 2024. DOI: 10.1016/j.jhsa.2024.07.009