An injury to the ulnar nerve at or near wrist or base of palm will result in paralysis of hypothenar muscles, all interosseous muscles, 1/2 of flexor pollicus brevis (FPB), the palmaris brevis, & adductor pollicis. There are some patients who will still have some intrinsic muscle function due to the martin gruber communication between the anterior interosseous branch of the median nerve (AIN) and the ulnar nerve. This occurs in 10-15% of people.
The main deficiencies are
- Sensory loss--includes the ulnar half of the ring and entire volar (palm) little finger. This surface area is important in protecting your hand as it is the surface that is rested upon a table or reached over a hot surface.
- Loss of active digital abduction/adduction -- results from paralysis of the four dorsal interossei, three volar interosse, and abductor digiti quinti (the intrinsic muscles of the hand)
- Claw (Duchenne's sign)--photo credit is less severe in a high ulnar nerve palsy with the absence or defieciency of the FDP flexor tone/pull. It is more significant in low ulnar palsy and in ligamentously lax individuals.
- Flattening of the metacarpal arch (Masse's sign)
- Pinch collapse--either Froment's sign (IP flexion) which is when the patient attempts to pinch with the thumb and index finger, the long flexor of the thumb is used to substitute for the thumb adductor, resulting in flexion of the thumb at the interphalangeal joint (photo credit) or Jeanne's sign (MP hyperextension)
- Abducted little finger (Wartenburg's sign)
- Dyskinetic finger flexion--With loss of the intrinsic muscles, the metacarpophalangeal joints of the ring and little fingers can only be flexed after flexion of the distal joints using the digital flexors. This reduces greatly the power of the grasp.
- Loss of power grasp and pinch
Conclusions regarding treatment, according to Hastings and Davidson, "Tendon transfers for correction of clawing deformity in ulnar nerve palsy are only consistently successful in young ligamentously lax individuals. Correction of deformity is most inconsistent in the intrinsically stiff hands of older individuals. Correction of clawing is more difficult in the little finger than in the ring finger. While use of the flexor digitorum superficialis for intrinsic transfer simply corrects clawing deformity and restores synchronous finger flexion, grip strength will be further decreased by approximately 21 percent, and total active range of motion by 7 percent. Correction is best achieved by transfer of a wrist motor with tendon graft into index, middle, ring, and little digits, despite limitation of clawing to the ring and little digits. Pinch should be augmented by metacarpophalangeal joint fusion rather than by interphalangeal joint fusion. When combined with extensor carpi radialis brevis adductor plasty, pinch strength can be doubled." photo credit
Table of options from Hastings and Davidson
|Low Ulnar Palsy||Ideal||Limited|
|Integrated finger flexion|
|ECRB and graft or FCR and graft transferred to index, middle, ring, little proximal phalanges||FDS from middle finger transferred to the ring and little A1 or A2 pulley|
|Pinch||MCP joint fusion|
EXRB and graft through 2nd and 3rd metacarpal interspace into adductor pollicis tendon
|MCP joint fusion|
|EPB transferred into the 1st dorsal interosseous|
|High Ulnar Palsy|
|Integrated finger flexion|
|ECRB and graft to the index, middle, ring, and little proximal phalanges|
|Pinch||Brachioradialis adductor-plasty through 2nd-3rd metacarpal interspace to the adductor pollicis tendon|
MCP joint fusion
|Finger flexion||Side-to-side FDP middle to FDP ring and little|
|EPB to the 1st dorsal interosseous|
Tendon Transfer Principles and Mechanics by Premal Sanghavi, MD --eMedicine Article
Low Ulnar Nerve Injury--Wheeless' Orthopaedic Online Textbook
Tendon transfers for ulnar nerve palsy; H. Hastings and S. Davidson; Hand Clinics, Vol 4(2) 1988, p 167-178.
Burkhalter Transfer for Claw Deformity--Wheeless' Orthopaedic
Ulnar Nerve Injury from patient's viewpoint-- Heather Gold's blog