- Irreparable nerve damage --Penetrating injuries can result in transection of the median, ulnar, or radial nerves or more centrally in the brachial plexus.
- Loss of function of a musculotendinous unit due to trauma or disease -- Rupture of the extensor pollicis longus (EPL) tendon is a common complication secondary to a distal radial fracture. Rheumatoid arthritis may be responsible for tendon rupture of any of the hand and wrist tendons, but it commonly leads to rupture of extensor tendons of the fingers or thumb (photo credit).
- In some non-progressive or slowly progressive neurological disorders -- These tends to be less responsive to surgical solutions, and can include stroke and neurologic diseases such as multiple sclerosis or cerebral palsy.
- The only absolute contraindication to tendon transfer is a lack of appropriate donors.
- The availability of muscle-tendon units with less than grade 5 strength is a relative contraindication.
- Similarly, if only muscles that have been denervated and then reinnervated are available, this is also a relative contraindication.
- Transfers planned in individuals with progressive neuromuscular diseases should be carefully considered before proceeding because the underlying disease process may affect the transferred unit.
- Lastly, satisfactory results are difficult to achieve in transfers performed to produce motion in less-than-supple joints.
- Most important functions of the Upper Extremity
- Grasp power (FDP & wrist stabilisers)
Pinch (FDP, FDS & intrinsics)
Positioning the hand
High ulna and median nerve injuries affect long flexors and grip
- Be sure that the tendon to be transferred can be spared from it's original location. The EIP has redundant function with the EDC and, thus, is expendable. Before transfer of the EIP, especially in a patient with rheumatoid arthritis, the surgeon should be confident that the EDC has not been affected by the disease and is functioning normally.
- Be sure that it is strong enough for its new task. Only muscles with power of 4+ should be considered donors as they always lose 1 MRC grade of power.
- Be sure it has enough amplitude for its movement. As a guide, amplitudes are as follows: Wrist motors 33mm; Finger extensors 50mm; Finger flexors 70mm.
- Be sure that is is under conscious voluntary control
- Be sure that its old action is synergistic with its new, or at least retrainable to it (photo credit--example of natural synergic movement: The effect shows extension of the fingers when the wrist is flexed and flexion of the fingers when the wrist is extended. If the tendons are not intact, this effect is lost.)
- Be sure that it can reach its new insertion without a sharp change of direction
- Be sure that it can get to its new location without going through dense scar tissue, through fascia, or across bare bone
- Be sure that the movement it is expected to produce is already freely possible by passive movement (no stiff or "frozen" joints)
- Be sure that they patient understands what is to be done and is ready to accept the postoperative discipline of exercises and training
(2) the transfer can act as a helper and add power to normal reinnervated muscle function
(3) the transfer can act as a substitute when, statistically, the recovery after neurorrhaphy or nerve repair is poor.
Tendon Transfer Surgery--American Society for Surgery of the Hand
Hand, Tendon Transfers by Philip E Higgs, MD--eMedicine article
Tendon Transfer Principles and Mechanics by Premal Sanghavi, MD and Mohammad Ali, MD--eMedicine article
Surgical Reconstruction and Rehabilitation in Leprosy and other Neuropathies by Richard Schwarz, MD
Peripheral Nerve Problems --Military Report by Colonel George E. Omer, Jr., MC, USA (Ret.), and Colonel William W Eversmann, Jr., MC, USA (Ret.)