Principles Principles of tendon transfers match muscle strength force proportional to cross-sectional area greatest force of contraction exerted when muscle is at resting length amplitude proportional to length of muscle work capacity = (force) x (amplitude) motor strength will decrease one grade after transfer should transfer motor grade 5 appropriate tensioning appropriate excursion can adjust with pulley or tenodesis effect Smith 3-5-7 rule 3 cm excursion - wrist flexors, wrist extensors 5 cm excursion - EDC, FPL, EPL 7 cm excursion - FDS, FDP surgical priorities elbow flexion (musculocutaneous n.) shoulder stabilization (suprascapular n.) brachiothoracic pinch (pectoral n.) sensation C6-7 (lateral cord) wrist extension and finger flexion (lateral and posterior cords) selection determine what function is missing determine what muscle-tendon units are available evaluate the options for transfer basic principles donor must be expendable and of similar excursion and power one tendon transfer performs one function synergistic transfers rehabilitate more easily it is optimal to have a straight line of pull one grade of motor strength is lost following transfer Presentation Physical exam brachial plexus injury Horner's sign correlates with C8-T1 avulsion often appears 2-3 days following injury severe pain in anesthetic limb indication of root avulsion loss of rhomboid function indication of root avulsion radial nerve palsy classified according to location of lesion proximal or distal to the origin of PIN low radial nerve palsy PIN syndrome high radial nerve palsy loss of radial nerve proper function (triceps, brachioradialis, ECRL plus muscles innervated by PIN) median nerve palsy classified according to location of lesion proximal or distal to the origin of AIN low median nerve palsy loss of thumb opposition (APB function) high median nerve palsy loss of thumb opposition loss of thumb, index finger, and middle finger flexion ulnar nerve palsy low ulnar nerve palsy loss of power pinch abduction of the small finger (Wartenberg sign) clawing results from imbalance between intrinsic and extrinsic muscles high ulnar nerve palsy loss of ring and small finger FDP function primary distinguishing deficit clawing less pronounced because extrinsic flexors are not functioning Studies Sensory and motor evoked potentials better than standard EMG/NCS Treatment Nonoperative physical therapy, splinting, and antispasticity medications indications decreased passive range of motion spasticity Operative early surgical intervention (3 weeks to 3 months) indications total or near-total brachial plexus injury high energy injury late surgical intervention (3 to 6 months) indications partial upper-level brachial plexus palsy low energy injury postoperative care protect for 3-4 weeks then begin ROM continue with protective splint for 3-6 weeks synergistic transfers are easier to rehabilitate (synergistic actions occur together in normal function, e.g., finger flexion and wrist extension) Specific Transfers & Indications Goal to regain FROM: Donor tendon (working) TO: Recipient Tendon (deficient) Musculocutaneous nerve palsy Elbow flexion Pectoralis major, latissimus dorsi Biceps Elbow flexion Common flexor mass Point more proximal on humerus (Steindler flexorplasty) Radial nerve & PIN palsy Elbow extension Deltoid, latissimus dorsi, or biceps Triceps Wrist extension Pronator teres ECRB Finger extension FDS, FCR, or FCU EDC Thumb extension Palmaris longus or FDS EPL Low median nerve palsy Thumb opposition and abduction FDS (ring) Base proximal phalanx or APB tendon (use FCU as pulley - classic Bunnell opponensplasty) EIP APB (pulley around ulnar side of wrist) High median nerve palsy Thumb IP flexion BR FPL Index and long finger flexion FDP of ring and small finger (ulnar nerve) FDP of index and middle (side-to-side transfer) Ulnar nerve palsy Thumb adduction FDS or ECRB Adductor pollicis Finger abduction (index most important) APL, ECRL, or EIP 1st dorsal interosseous Reverse clawing effect FDS, ECRL (must pass volar to transverse metacarpal ligament to flex proximal phalanx) Lateral bands of ulnar digits Complications Adhesions necessitate aggressive therapy and possible secondary tenolysis Prognosis Age leading prognostic factor worse after age 30 Anatomic location distal is better than proximal