Outcome from a brachialis donor for wrist extension in tetraplegia-time to reconsider the International Classification for Surgery of the Hand in Tetraplegia (ICSHT)

Abstract

Introduction: Surgical reconstruction after quadriplegia represents a powerful solution to restore lost function by injury. A case is presented in which surgical reconstruction of a patient with a C4 level spinal cord injury is performed using the brachialis (BRA) muscle as the donor.

Case presentation: The patient previously had no hand function. This transfer, in combination with fusion of the thumb CMC joint and transfer of the flexor pollicis longus (FPL) tendon to the radius, gives the patient full thumb key pinch powered by BRA transferred to the wrist extensors. Theoretical analysis of muscle architectural properties demonstrates that the BRA has sufficient force and excursion to substitute for both the long and short radial wrist extensors. Furthermore, based on the fact that the BRA has almost twice the excursion compared to the extensor carpi radialis longus (ECRL), wrist extension can occur throughout the entire wrist and elbow ranges of motion. Finally, peak tension is lower than the rupture tension previously measured by us using this type of tendon-to-tendon attachment technique, suggesting that the transfer itself is safe and, importantly, can be immediately mobilized for neuromuscular rehabilitation.

Discussion: This procedure can thus restore tremendous functional capacity in patients who were previously categorized as group 0 by the International Classification of Hand Surgery in Tetraplegia (ICSHT). We suggest that, based on the BRA being an excellent donor for surgical reconstruction, that the ICHST system be reconsidered.

Fig. 1. Timeline of patient training and treatment.

2017: Patient was first assessed. 2018: Preoperative training performed. 2019: Preoperative training focusing on ADLs. 2020: Dynamic muscle strengthening, and goal directed ADLs performed. 2021: Completion of strengthening and training program.

Fig. 2. Intraoperative images of surgical procedure.

A Brachialis (BRA) tendon is isolated. B Tibialis anterior (TA) interpositional graft extended from BRA to extensor carpi radialis brevis (ECRB) distal tendon. C Transferred BRA is “tensioned” into the ECRB tendon to achieve wrist extension.

Fig. 3. Photographs of patient 2 years postoperatively.

A Passive key pinch is achieved by active wrist extension powered by the BRA. B Protruding BRA tendon produced by active voluntary contraction indicates that substantial force is generated by the transferred muscle. C Medial view of passive key pinch enabled by CMC1 tenodesis and FPL transfer into the radius.

Fig. 4. Theoretical prediction of BRA-to-ECRB tendon transfer outcome.

A Graphical representation of BRA and ECRB path before transfer (left) and BRA–ECRB path after transfer (right) r based on previously published values [17] and the BRA–ECRB moment arm measured topographically (solid circles in B). B Muscle moment arm from elbow joint to BRA before transfer (blue) and BRA-ECRB after transfer (red). C Prediction of active (left panel) and passive (right panel) force of the transferred BRA–ECRB at all possible combinations of elbow and wrist joint angles based on insertion of an 18 cm long TA tendon 72 mm proximal to the wrist joint crease. A more thorough presentation of this model is presented elsewhere [14].