Introduction

Spinal cord injury is devastating to the patient, the family, and his or her friends. In an instance, life has downgraded dramatically with respect to ambulation, limb usage, bladder/bowel function, and independence. Spinal cord injury has substantial physical, emotional, and psychosocial ramifications. Approximately 54 people per million sustain injuries to the spinal cord each year (17,000 new cases per year), with about half occurring at the cervical spine and 14% resulting in ventilator dependence. Currently, over 300,000 Americans live with some residual paralysis from a spinal cord injury. Most of the persons are young men when the spinal injury occurred, and many require lifelong care to complete their activities of daily living (ADLs) such as feeding, dressing, bathing, bladder/bowel care, and mobility. Maintenance cost estimates for care range from $40,000 to $185,000 per year per patient, depending on the severity and level of the injury. This expensive care places substantial physical and financial stressors on the patient and family.

Spinal cord injuries can be complete or incomplete. In complete injuries, the spinal cord is interrupted blocking any efferent or afferent pathways. In incomplete injuries, the spinal cord maintains some continuity allowing some signal across the injured segment. There are numerous incomplete injury patterns dependent upon the extent and location of the injured and preserved pathways. Hence, the prognosis for spontaneous recovery following incomplete spinal cord injury is more optimistic and varies with the degree of damage.

Since the end of the Second World War, the care for persons with spinal cord injury has considerably improved. There have been advances in numerous aspects of care including the acute management immediately following the injury, the initial rehabilitation to minimize the immediate sequelae of the injury, and the reconstructive surgical options to improve upper limb usage along with crucial bladder/bowel function. Tendon and nerve transfer surgery are the mainstay procedures to enhance upper limb function. The algorithm for incomplete spinal cord injury follows the same principles as complete spinal cord injury although the variability in presentation negates the establishment of a defined paradigm.

Classification

The American Spinal Injury Association Impairment Scale is most commonly used to classify the level and severity of the injury. This classification documents motor and sensory findings and provides a scoring system. With reference to the upper extremity, the International Classification of Surgery of the Hand in Tetraplegia (ICSHT) is more relevant for planning upper limb reconstruction ( Table 15.1 ). The objective is to identify those muscles distal to the elbow that are potentially transferrable. The classification follows the American Society for Spinal Cord Injury cataloging, but emphasizes muscle strength. Therefore, each muscle below the elbow that is a Grade 4 or greater muscle strength adds an additional grade. The muscle strength and gradation is based upon the muscle’s primary nerve innervation. For example, the brachioradialis is mainly innervated by C5. When the brachioradialis muscle is present and strong, but no other muscles are of similar strength, the ICSHT is Grade 1. The subsequent ICSHT grades are also based upon the succeeding muscle principal nerve innervation. In other words, the extensor carpi radialis longus is mainly a C6 muscle. The extensor carpi radialis brevis is principally a C7 muscle as are the pronator teres, flexor carpi radialis, extensor digitorum communis, extensor pollicis longus, and flexor digitorum superficialis. The flexor digitorum profundus and intrinsic muscles are mainly innervated by C8 and T1 nerve roots. The addition of another strong muscle continually adds a grade to the classification and expands the potential surgical options for upper extremity reconstruction.

Referral for Upper Limb Reconstruction

The referral process for persons with spinal cord injury remains disorganized and underutilized. Chung and colleagues have shown that approximately 65% of the 5000 cervical spine injures per year would benefit from upper limb reconstruction by improving function and increasing independence. Despite the potential benefits, less than 500 surgeries are performed annually to improve upper limb function. This disconnect is multifactorial with responsibility levied on physiatrists, surgeons, and institutions.

Published reports of tendon transfers for person with spinal cord injury have shown improvement in quality of life and overall function. Despite this evidence, many physicians and even spinal cord rehabilitation facilities remain wary or are unaware of the potential benefits. Many patients that would benefit from surgical reconstruction are never referred for surgical evaluation. With the advent of nerve transfers, this problem will escalate unless knowledge dispersion increases across all subspecialties that manage persons with spinal cord injury. A person with spinal cord injury can typically gain one cervical spinal level of function through tendon transfers. Augmenting the current tendon transfer paradigm with nerve transfers can restore two cervical spinal cord levels of function. However, nerve transfers require a viable muscle target for reinnervation, and irreversible motor endplate demise occurs as early as 18 months from injury. Therefore, most nerve transfers have limited success after 12 months from injury. This window of opportunity highlights the time sensitivity and necessity of prompt referral for upper limb reconstruction.

Tendon Versus Nerve Transfer

Tendon transfers for upper limb reconstruction have been the gold standard for improving function. Pioneers in tetraplegic surgery, such as Moberg, Zancolli, House, and others, have established the basic tenets of tendon donor and recipient selection. Innovators in nerve surgery, such as Oberlin, MacKinnon, and Bertelli, have introduced nerve transfers into the treatment paradigm. The common prerequisite for tendon and nerve donor selection remains availability and expendability. In other words, the donor must be available (i.e., strong) and expendable (i.e., the limb can function without the donor nerve or tendon). An expendable donor usually has another muscle that performs the same task. For example, if the patient has an intact extensor carpi radialis longus and brevis tendons, the extensor carpi radialis longus can be transferred without jeopardizing wrist extension.

Nerve transfers warrant further discussion regarding an upper versus lower motor neuron injury. Above the level of injury, the nerve and spinal cord are normal. The afferent and efferent signals are received and transmitted to and from the central nervous system (brain and spinal cord). At the level of injury, there is direct damage to the cord and anterior horn cells. This lower motor neuron injury leads to Wallerian degeneration and secondary muscle changes over time, such as atrophy and fibrosis. This process can be reversed by transferring a donor nerve downstream into a terminal branch of the damaged spinal cord. For example, a lower motor neuron injury to the spinal cord at C7 can be circumvented by transferring a C6 nerve (e.g., supinator nerve) to a C7 motor nerve (e.g., extensor digitorum communis) to regain digital extension. However, nerve transfer procedures for a lower motor neuron injury are time dependent. The surgery must be performed with ample time for nerve regeneration (1 mm/day) to reach the muscle end plate before prevent permanent atrophy and fibrosis (18 months after lower motor neuron injury). Therefore, nerve transfers for lower motor neuron injury are preferably performed within 1 year from injury.

Below the level of injury, the nerve and spinal cord are also normal. However, the afferent and efferent signals are not received by the central nervous system that resides above the damaged cord (brain and spinal cord). This injury is called as an upper motor neuron injury. This situation prohibits volitional activation of these muscles, but promotes involuntary movement, as the dampening effect of the brain is absent. These muscles remain innervated and become spastic, a process that maintains muscle viability. Hence, nerve transfers for an upper motor neuron injury can be performed years after injury as permanent muscle atrophy and fibrosis do not occur. However, some central nervous system pruning may have a negative effect on restoring active movement.

Hierarchy of Upper Limb Function

The most common level of cervical spine injury is C5–C6, which leads to ICSHT Grades 1–3. Triceps function is absent, and restoration of elbow extension carries a high priority. The lack of elbow extension hinders function. Deficient elbow extension has multiple negative consequences. Workable reach space is drastically decreased, as the arm is unable to reach out into space. Daily activities for persons with spinal cord injury are compromised such as pushing a wheelchair, transferring in and out of a bed or a chair, and weight shifting for avoiding decubitus. Reestablishment of elbow extension can have a dramatic increase in reachable workspace, facilitate wheelchair propulsion (uphill and on carpeted surfaces), and facilitate transfers in and out of bed or chair.

The management of the wrist and hand in tetraplegia follows the concepts of “hierarchy of hand function” or the “reconstruction ladder” ( Table 15.2 ). The primary fundamental movement is wrist extension, which yields tenodesis for grip as the fingers flex into the palm and tenodesis for lateral pinch as the thumb adducts against the index finger. Wrist extension also aligns the finger flexors along Blix’s length–tension curve for maximum active grip. The second most essential movement is lateral pinch, which is necessary to perform numerous ADLs. Most daily activities are accomplished with lateral pinch, such as holding an object, turning a key, or using a fork ( Fig. 15.1 ). The third essential motion is grasp, which allows the holding of objects ( Fig. 15.2 ). The fourth and last movement is digital opening for object acquisition. The reason to place this function lowest on the ladder is that wrist flexion yields passive digital opening, which is often adequate for object procurement. In addition, synchronous digital opening is difficult to achieve via surgery as metacarpophalangeal joint extension is mainly an extrinsic function (extensor digitorum communis, extensor indicis proprius, and extensor digiti quinti) and interphalangeal joint extension is primarily an intrinsic function (interossei and lumbricals). The only way the extrinsic system can elicit interphalangeal joint extension is by limiting metacarpophalangeal joint extension (e.g., Zancolli tenodesis of the flexor digitorum superficialis). This procedure can cause problems such as limiting flexor digitorum profundus excursion and/or attenuating over time. Restoring both metacarpophalangeal and interphalangeal movements by tendon transfer(s) remains a daunting task replete with complications.

Lateral pinch is the prehension used for most activities of daily living.

Courtesy of Shriners Hospital for Children, Philadelphia.

Grasp is imperative for holding and retaining objects within the hand.

Courtesy of Shriners Hospital for Children, Philadelphia.

Elbow Reconstruction

Most persons with cervical spine injury lack triceps function and elbow extension. Restoration of elbow extension carries a high priority. The lack of elbow extension truly hinders function and workable reach space. Elbow extension is a high surgical priority and can be accomplished by nerve or tendon transfer.

Nerve

The principal donor nerve is the posterior branch of the axillary nerve. The axillary nerve has three terminal branches (larger anterior deltoid, smaller posterior deltoid, and teres minor branch). Before surgery, the strength of the posterior deltoid must be strong to ensure an adequate donor nerve. The transfer is completed via an axillary approach ( Fig. 15.3A–C ). The axillary nerve is identified just proximal to the latissimus dorsi tendon. The three branches are isolated and verified by electrical stimulation. The posterior axially nerve is selected as the donor nerve. The radial nerve is isolated just anterior to the axillary nerve in the arm. Electrical stimulation is helpful as long as the nerve is stimulatable. The triceps motor nerve is isolated. There can be a common branch to all three heads of the triceps muscle, or separate nerve branches can be found. The donor axillary nerve is cut as distal as possible (donor distal) and the recipient triceps motor nerve as proximal (recipient proximal) to negate any tension across the repair. The coaptation between the posterior branch of the axillary nerve and the motor branch to the triceps is secured with microsuture and/or fibrin glue.

A 16-year-old male 6 months following cervical spine injury. He is ICSHT Grade 1 on both arms and is undergoing nerve transfer of the posterior axillary branch to the triceps motor nerve. (A) Axillary nerve and branches isolated. Red loop around axillary nerve and larger anterior branch. Yellow loop around posterior branch and scissors behind teres minor branch. (B) Axillary nerve and motor branch to the triceps isolated (loose yellow loop). (C) Coaptation between posterior axillary branch and motor nerve to the triceps muscle.

Courtesy of Shriners Hospital for Children, Philadelphia.

Tendon

The two main donors are the biceps and the posterior deltoid muscles. Each procedure has its own nuances, positives, and negatives. The biceps to triceps is easier and has a less rigid postoperative rehabilitation. The posterior deltoid transfer requires an intervening graft that complicates the technique and adds greater postoperative restrictions. We prefer the biceps over the triceps transfer to the deltoid to triceps transfer.

The biceps-to-triceps tendon transfer requires the biceps to be expendable. Therefore, active brachialis and supinator muscles are prerequisites to maintain elbow flexion and forearm supination. The evaluation of their presence requires an attentive physical examination of elbow flexion and forearm supination strength. Effortless forearm supination without resistance will cause supinator function that is palpable along the proximal radius. Similarly, powerless elbow flexion will result in a palpable brachialis contraction along the anterior humerus deep to the biceps muscle. Equivocal cases require additional measures to assure adequate supinator and brachialis muscle activity. Injection of the biceps muscle with a local anesthetic induces temporary paralysis of the biceps muscle and allows independent assessment of brachialis and supinator muscle function.

A supple elbow with near complete range of motion is also necessary. Otherwise, the biceps tendon will not reach the olecranon during surgery. Therapy and/or serial casting can decrease the contracture. Surgery is delayed until the contracture is less than 20 degrees.

The surgery is performed via an S-shaped incision along the medial arm, across the antecubital fossa, and over the brachioradialis muscle belly ( Fig. 15.4A–F ). The biceps tendon is traced to its insertion into the radial tuberosity. The tendon is released at its insertion into the radial tuberosity to maximize length. The tendon and muscle belly are mobilized in a proximal direction to maximize excursion and to improve line of pull. Along the medial side of the arm, the median nerve, brachial artery, and ulnar nerves are isolated.

A 16-year-old female 2 years following cervical spinal cord injury. She is ICSHT Grade 2 on both arms and is undergoing biceps-to-triceps tendon transfer. (A) Biceps passed along the medial side of the arm to the posterior incision beneath the ulnar nerve. (B) Biceps passed beneath the ulnar nerve. (C) Biceps tendon passed though triceps tendon before docking into olecranon. (D) Suture retrievers to facilitate docking biceps tendon into osseous tunnel. (E) Biceps tendon docked into olecranon. (F) Postoperative immobilization.

Courtesy of Shriners Hospital for Children, Philadelphia.

A separate posterior incision is performed around the olecranon and extended in a proximal direction along the triceps tendon. A subcutaneous tunnel is created between the medial arm and posterior olecranon incision for tendon passage. The tendon is passed over the median nerve and under the ulnar nerve to avoid any ulnar nerve compression. The triceps tendon is split and the tip of the olecranon is exposed. A large bore blind bone tunnel is drilled in the olecranon for acceptance of the biceps tendon. The tendon is passed through the medial leaflet of the triceps tendon and docked into the bone tunnel using suture within the tendon and posterior unicortical holes. The sutures are tied over the posterior olecranon cortex. Additional suturing is performed during closure of the triceps split with incorporation of the biceps tendon. Following closure, a well-padded long arm cast or splint is applied with the elbow in extension. The wrist is included within the cast and the hand position depends upon concomitant procedures performed for hand function.

Rehabilitation

Nerve rehabilitation is much less arduous than tendon rehabilitation. Following a brief period of immobilization to allow for wound healing, the arm allowed normal usage. Nerve regeneration from the axillary to the motor branch of the triceps muscle occurs at a rate of 1 mm/day. The patients are instructed to link shoulder extension (posterior deltoid function) with elbow extension to promote cortical learning. This combined movement pattern is performed numerous times per day awaiting nerve regeneration. When the posterior branch of the axillary nerve regenerates to the triceps activity, the patient will “learn” to fire his or her triceps independent of shoulder extension.

Tendon rehabilitation requires supervised therapy for months. The biceps to triceps can be mobilized early (7–10 days) or delayed (3 weeks) depending upon the patient’s age, patient’s compliance, and the strength of the tendon transfer repair ( Protocols 15.1 and 15.2 ). The rehabilitation is divided into three phases: early mobilization, mobilization, and strengthening/functional retraining. Mobilization is initiated in gravity-eliminated plane within a limited arc of flexion. Flexion is progressively increased 15 degrees per week as long as no extension lag develops. Strengthening and wheelchair propulsion are prohibited until 12 weeks from surgery. Transfers and weight shifts are initiated 16 weeks from surgery. Antigravity elbow extension is obtainable in the vast majority of cases ( Fig. 15.5 ).

Protocol 15.1

Biceps-to-Triceps Transfer Early Mobilization.

Early mobilization phase 1–5 weeks post-op	Patient is immobilized in bivalved long arm cast or in fabricated splint with elbow in full extension, except during therapy session Precautions: • Avoid shoulder flexion/abduction above 90 degrees and extension of shoulder beyond 0 degrees • No active elbow flexion until 4 weeks post-op Therapeutic intervention • Begin early mobilization—passive elbow flexion to 30 degrees, active elbow extension to 0 degrees • Initiate exercises in gravity-eliminated plane, blocking compensatory external rotation and supination • ROM (Range of Motion) of uninvolved joints • Edema management • Week 4: add active elbow flexion in therapy only to 30 degrees
Mobilization phase 5–8 weeks post-op	Cast removed Precautions: • Avoid shoulder flexion/abduction above 90 degrees and extension of shoulder beyond 0 degrees until 6 weeks post-op • Active elbow flexion and extension is progressed in increments of 15 degrees elbow flexion each week • No elbow flexion beyond allowed elbow range of motion • Do not progress elbow flexion if extension lag is present • No resistive exercises/weight bearing Splint • Weeks 5–8: • Bledsoe to be worn during the day. At week 5, elbow flexion block at 45 degrees. • Adjust Bledsoe in increments of 15 degrees of flexion per week as patient progresses. Do not increase range in brace if extension lag is present. Therapeutic intervention • Active elbow flexion to 45 degrees, active extension full. Progress in increments of 15 degrees of flexion per week as patient progresses. Do not increase range if extension lag is present. • Initiate exercises in gravity-eliminated plane, blocking compensatory external rotation and supination • Decrease amount of flexion if extension lag is present. If lag is present focus on end range extension • Edema control and scar management Functional Training With Bledsoe on, light functional training or activities may begin in allowed elbow ranges (pending time frame and assessment of allowed amount of elbow flexion) only after the therapist is sure, the transfer is firing with the activity.
Strengthening and functional retraining phase 9–12 weeks post-op	Splint • Discontinue Bledsoe splint after 1 week at 90 degrees flexion block (as long as no extension lag present) • Static extension splint at night Precautions • No resistive exercises or weight bearing • No passive elbow flexion Therapeutic interventions • Same as described earlier, add against gravity elbow extension as tolerated Functional training • Same as described earlier
Strengthening/resistive activities	• May begin light progressive resistive exercises at 12 weeks post-op • May begin manual wheelchair propulsion when cleared by surgeon (12–16 weeks post-op) • No restrictions (may resume transfers/weight shifts) at 16 weeks post-op

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