Novel Concepts Integrated in Neuromuscular Assessments for Surgical Restoration of Arm and Hand Function in Tetraplegia

Surgical restoration of key functions of the upper extremity has tremendous potential to increase autonomy, mobility, and self-esteem by resuming critical abilities in patients with tetraplegia. New strategies of surgical reconstruction and postoperative rehabilitation of upper extremity function in tetraplegic patients have been developed, based on basic science and clinical studies. In contrast to traditional hand reconstruction with separate flexors and extensors phases, combining 7 individual procedures provides key pinch and finger flexion together with passive opening of hand in one stage. Further research should aim at combining traditional algorithms with new approaches, such as immediate postoperative activation, combined procedures and nerve transfers.

In the United States alone, approximately 225,000 to 300,000 persons live with a spinal cord injury (SCI), and about 12,000 new SCI injuries occur every year, mostly in young, healthy, and active individuals in their most productive years. More than 50% of all SCIs occur at the cervical level and lead to tetraplegia.

Upper extremity function is, apart from the brain, the most important functional resource of tetraplegic patients and is judged to be the most desirable ability to regain after cervical SCI before bowel, bladder, sexual function, or walking ability. Surgical rehabilitation of arm and hand abilities can indeed meet many of patient’s requirements. Although regrettably greatly underused, tendon transfer surgery is a powerful tool to improve upper extremity function, and an asset to enhance self-esteem and increase spontaneity. Transfers can provide a certain amount of autonomy for persons with tetraplegia and allow them to regain meaningful roles and productive work. Restoration of hand function can eliminate the need for adaptive equipment for eating, personal care, catheterizing, and other activities of daily living. Results from more than 500 cases in 14 studies were recently summarized, and revealed a mean increase of Medical Research Council score for elbow extension from 0 to 3.3 after reconstruction and a mean postoperative pinch strength of 2 kg, which markedly improved upper extremity usability.

This article summarizes novel concepts of surgical restoration of arm and hand function based on neuromuscular assessment.

Anatomy and clinical examination

Muscle Testing

Surgical planning depends on preoperative evaluation of the upper extremity, and includes muscle strength tests according to the British Research Council system and International Classification of Surgery of the Hand in Tetraplegia (ICSHT) ( Tables 1 and 2 ).

Table 1

Muscle function according to British Research Council system

Muscle Strength Grade	Muscle Function
M0	No active range of motion, no palpable muscle contraction
M1	No active range of motion, palpable muscle contraction only
M2	Reduced active range of motion—not against gravity, no muscle resistance
M3	Full active range of motion, no muscle resistance
M4	Full active range of motion, reduced muscle resistance
M5	Full active range of motion, normal muscle resistance

Table 2

International Classification of Surgery of the Hand in Tetraplegia

Group	Spinal Cord Segment	Possible Muscle Transfers	Possible Axon Sources for Nerve Transfers
0	≥C5	No transferable muscle below elbow	Musculocutaneous nerve branches to coracobrachialis and brachialis muscle
1	C5	Brachioradialis (BR)	Axillary nerve branches to deltoid and teres minor muscles
2	C6	+ Extensor carpi radialis longus (ECRL)	Radial nerve branches to supinator muscle
3	C6	+ Extensor carpi radialis brevis (ECRB)
4	C6	+ Pronator teres (PT)
5	C7	+ Flexor carpi radialis (FCR)
6	C7	+ Extensor digitorum
7	C7	+ Extensor pollicis longus
8	C8	+ Flexor digitorum	Radial nerve branch to ECRB muscle
9	C8	No intrinsic hand muscles
10 (X)		Exceptions

The donor muscle must be healthy and of adequate strength (M4), preferably not injured or reinnervated, yet with limited available donor muscles; a weaker muscle (M3) may be considered for transfer. Optimally it should be synergistic, similar in architecture, and have an adequate soft-tissue bed along the route of transfer.

Joint Range of Motion

Passive joint motion is a prerequisite for active and passive functional reconstruction. A tenodesis effect during wrist extension (hand closure), flexion (hand opening), and joint stability (primarily the thumb carpometacarpal [CMC] joint) is preferable but not required for reconstruction.

Sensibility Testing

Sensory examination focuses on cutaneous afferences of the hands with a 2-point discrimination, which should be 10 mm or better in the thumb for cutaneous control (Cu); otherwise ocular control (O) is required.

Special aspects

Other aspects of neuromuscular examination include brachial plexus lesions and entrapment neuropathies, paralytic spine deformity, thoracoscapular stability, spasticity, contractures, stiffness, and instability of joints. Pain and swelling are relative contraindications to surgery and need to be treated before reconstruction.

Planning of reconstruction

The main goals are reconstruction of elbow extension, grip function (flexion phase), and opening of the hand (extension phase). The most frequently used procedures to achieve patients’ ability goals and an algorithm for surgical reconstruction based on International Classification (IC) are presented in Tables 3 and 4 , respectively.

Table 3

Summary of possible surgical procedures (excluding nerve transfers) to achieve patients’ ability goals

Ability Goal	Functional Goal	Procedure	Rehabilitation
Stabilizing elbow in space, reaching overhead objects, pushing wheelchair, stabilizing trunk	Elbow extension	Reconstruction of triceps function Posterior deltoid-triceps Biceps-triceps	4-wk in cylinder cast with elbow fully extended 4-wk orthosis
Use of utensils, handwriting, pushing wheelchair	Grip	Reconstruction of grip
		Reconstruction of passive key grip BR-ECRB FPL-radius CMC I arthrodesis	4 wk with arm in cast with flexed thumb and wrist 4–10 wk active exercise
		Reconstruction of active key grip BR-FPL CMC I arthrodesis Split FPL-EPL tenodesis	4 wk in orthosis with active key pinch but restriction of wrist extension
Reaching for objects, eg, cup or glass positioning of thumb and fingers for improved grasp control	Opening of the hand	Reconstruction of thumb and finger extensors
		Passive opening CMC I arthrodesis EPL to extensor retinaculum attachment	4 wk wrist and thumb in cast
		Active opening PT-EDC and EPL/APL	4 wk wrist, fingers, and thumb in cast
		Reconstruction of intrinsics Zancolli-lasso tenodesis House tenodesis EDM-APB	4 wk of immobilization in intrinsic plus position. Thumb actively exercised 1st postoperative day

Abbreviations: APB, abductor pollicis brevis; APL, abductor pollicis longus; BR, brachioradialis; CMC, carpometacarpal; ECRB, extensor carpi radialis brevis; EDC, extensor digitorum communis; EDM, extensor digiti minimi; EPL, extensor pollicis longus; FPL, flexor pollicis longus; PT, pronator teres.

Table 4

Surgical algorithms according to International Classification (IC)

IC Group	Surgical Options	Alternatives
0	Abducted shoulder (AD transfer) Flexion contracture of the elbow (biceps tendon Z-tenotomy) Supinated but not contracted forearm (Zancolli: rerouting the biceps; check the presence of supinator muscle!) Fixed supination contracture (osteotomy of radius) Unstable or contracted wrist (wrist fusion)
1	BR-to-ECRB for active wrist extension Split-thumb tenodesis Moberg’s key pinch procedure
2	BR-to-FPL for active key pinch Split-thumb tenodesis I. CMC fusion EPL tenodesis to the retinaculum	BR-to-FDP II–IV active grip Moberg’s key pinch procedure Split-thumb tenodesis CMC I fusion EPL tenodesis to the retinaculum Zancolli-lasso procedure
3	BR-to-FPL ECRL-to-FDP II–IV Split-thumb tenodesis Zancolli-lasso or House intrinsic procedure CMC I fusion EPL tenodesis	BR-to-FDP II–IV Moberg’s key pinch procedure Split-thumb tenodesis Zancolli-lasso or House intrinsic procedure CMC I fusion EPL tenodesis
4	BR-to-FPL ECRL-to-FDP II–IV Split-thumb tenodesis Zancolli-lasso or House intrinsic procedure CMC I fusion EPL tenodesis PT-to-FDS II–V (activated Zancolli lasso) or PT-to-FPL or PT transfer in extensor phase
5	BR-to-FPL ECRL-to-FDP II–IV Split-thumb tenodesis Zancolli-lasso or House intrinsic procedure CMC I fusion EPL tenodesis PT-to-FDS II-V (activated Zancolli lasso) or PT transfer in extensor phase	PT-to-FPL ECRL-to-FDP II–IV Split-thumb tenodesis Zancolli-lasso or House intrinsic procedure BR-to-APB EPL tenodesis
6	BR-to-FPL ECRL-to-FDP II–IV Split-thumb tenodesis Zancolli-lasso or House intrinsic procedure EDM-to-APB transfer EDC-to-EPL	PT-to-FPL ECRL-to-FDP II–IV Split-thumb tenodesis Zancolli-lasso or House intrinsic procedure BR-to-APB EDC-to-EPL ECU or FCU-to-FDS II–IV (activated Zancolli lasso)
7	BR-to-FPL ECRL-to-FDP II–IV Split-thumb tenodesis? Zancolli-lasso or House intrinsic procedure EDM-to-APB or EIP-to-APB or FCU-to-APB Activated Zancolli lasso (PT-to-FDS II–V)	PT-to-FPL BR-to-FDS II–IV ECRL-to-FDP II–IV Split-thumb tenodesis? Zancolli-lasso or House intrinsic procedure EDQ-to-APB or EIP-to-APB or FCU-to-APB or activated Zancolli lasso (BR-to-FDS II–V)
8	BR-to-FPL ECRB-activated APB Opponens plasty (EIP, EDM, FCU) Active Zancolli-lasso procedure (ECU) House intrinsic procedure	PT-to-FPL ECRB-activated APB Opponens plasty (EIP, EDM, FCU) Active Zancolli-lasso procedure (BR) House intrinsic procedure
9	Zancolli lasso House intrinsic procedure
10	Pathologic postures (MP joints fixed in hyperextension, lack of any functioning intrinsic muscles, wrist fixed in either flexion or extension, etch) Release of contracted muscles, tendons, and joint capsules

Abbreviations: APB, abductor pollicis brevis; APL, abductor pollicis longus; BR, brachioradialis; CMC, carpometacarpal; ECRB, extensor carpi radialis brevis; ECRL, extensor carpi radialis longus; ECU, extensor carpi ulnaris; EDC, extensor digitorum communis; EDM, extensor digiti minimi; EDQ, extensor digitorum quinti; EIP, extensor indicis proprius; EPL, extensor pollicis longus; FCU, flexor carpi ulnaris; FDP, flexor digitorum profundus; FDS, flexor digitorum superficialis; FPL, flexor pollicis longus; MP, metacarpophalangeal; PT, pronator teres.

Reconstruction of Elbow Extension

Elbow extension is critical for overhead activities, weight shifting, and transfers, and greatly increases wheelchair propulsion and the workspace of the hand in space by 800%. Elbow reconstruction should precede grip reconstruction because

•

use of a hand that cannot reach out in space is very limited,
•

elbow extension helps to stabilize the patient’s trunk in the wheelchair,
•

stability itself is a factor for more controlled use of the hand, and
•

function of distal tendon transfers is improved, for example, brachioradialis (BR) muscle function (as a donor) requires a counteracting and stabilizing action from its antagonist, that is, elbow extension.

Two surgical procedures are advocated to restore active elbow extension:

1.

Posterior deltoid-to-triceps transfer ( Fig. 1 )

Fig. 1

Drawing demonstrating surgical reconstruction of elbow extensor using posterior deltoid to triceps via an interpositioning tibialis anterior tendon graft. ( A ) The posterior deltoid border is mobilized and the interval between middle and posterior deltoid identified. Care is taken to identify the posterior deltoid insertion that is subsequently detached along with the associated periosteum. A subcutaneous tunnel is created from the level of deltoid insertion to the distal triceps tendon via a dorsal incision to the level of olecranon. The distal deltoid tendon and the tendon graft are placed with an overlap of 5 cm and sutured to each other using 2/0 nonabsorbable running sutures along the sides of the graft and host tendons. ( B ) The distal graft insertion is created by threading the tendon graft through a hole made in the flat triceps tendon and sutured with overlap of 5 cm using 2/0 nonabsorbable running sutures up and down along both sides of the graft and host tendons.
2.

Biceps-to-triceps transfer.

Posterior deltoid-to-triceps transfer reliably restores lost elbow extension in patients with C5/6 tetraplegia. Patient candidates for biceps-to-triceps transfer usually demonstrate intact and functional brachialis and supinator muscles, biceps spasticity, and elbow flexion contracture exceeding approximately 20°. The result of reconstruction of elbow extension is generally very good, and provides the person with tetraplegia with improved arm control, useful in many daily activities ( Fig. 2 ).

Reconstruction of Forearm Pronation

In patients affected by high-level tetraplegia (groups 0 and 1), impaired balance between functional forearm supinators and weakened or paralyzed pronators may produce supination contracture. Surgical options include:

a.

Distal transposition of biceps tendon (rerouting), if necessary with interosseous membrane release
b.

Dorsal transposition of the BR during BR-to-flexor pollicis longus (FPL) transfer to achieve simultaneous thumb flexion and forearm pronation ( Fig. 3 )

Fig. 3

Brachioradialis tendon is transferred dorsally and through the interosseous membrane (from dorsal to palmar muscle compartment) before being inserted into the flexor pollicis longus (FPL) tendon (not visible). Using this route, activation of the brachioradialis will power both thumb flexion and forearm pronation.
c.

Derotation osteotomy of the radius.

Reconstruction of Wrist Extension

Reconstruction of active wrist extension is of utmost importance because of the wrist-related tenodesis effect. If wrist extension is absent (IC groups 0 and 1), the BR (only IC group 1) can be transferred for wrist extension onto the extensor carpi radialis brevis (ECRB) to obtain a wrist extension without radial deviation (as if extensor carpi radialis longus [ECRL] is wrongly used).

Reconstruction of Grip Function

Tetraplegic patients usually have a spontaneous weak pinch between the thumb and index finger, depending on wrist extension/tenodesis grip. To produce a useful grip, preoperative planning must be based on patients’ goals and wishes and thorough testing of muscle function, sensibility, and spasticity of the hand. In IC 2, the patient’s active extension of the wrist depends only on the ECRL muscle; therefore, this muscle must not be used for a transfer in this group of patients. In IC 3 and higher, where active extension is supplied by both the ECRL and ECRB, the ECRL can be used for active transfers.

Reconstruction of key pinch

Lateral pinch, termed key grip, is based on the fact that the hand opens by passive or active wrist flexion and closes by wrist extension, whereby the thumb pulp ideally should meet the radial side of the middle phalanx of index finger ( Fig. 4 ). Prerequisites for passive key grip are wrist extension, minimum strength grade 3, forearm pronation, and acceptable relationship between thumb and index/long finger. Stabilizing procedures are split FPL–extensor pollicis longus (EPL), distal thumb tenodesis, and CMC I arthrodesis. Active key pinch is preferably achieved by BR-FPL tendon transfer ( Fig. 5 ).

Reconstruction of power grip: ECRL–flexor digitorum profundus (FDP) tendon transfer

Active whole-hand closure is powered by ECRL tendon transfer on the deep finger flexors 2 to 4, excluding the little finger, to prevent hyperflexion ( Fig. 6 ).

Reconstruction of Intrinsics

The purpose of interossei reconstruction is to secure MCP joint flexion. Key pinch can be achieved by positioning the index finger so that it is sufficiently flexed to meet the thumb, and also creating support by digits 3 to 5. Second, extension of the PIP joints is essential for grasp and release, and provides a more normal opening of the hand compared with reconstruction of extensor digitorum communis (EDC) function, giving an intrinsic minus type of opening. Passive interossei function of the fingers using passive tenodesis by tendon grafts in the lumbrical canals (house procedure) is shown in Fig. 7 . Restoration of palmar abduction of the thumb is illustrated in Fig. 8 .