- Discussion:
- claw hand deformity is manifested by flattening of the transverse metacarpal arch and longitudinal arches,
with hyperextension of MCP joints and flexion of the PIP and DIP joints;
- deformity is produced by imbalance of the intrinsic & extrinsics;
-
intrinsic muscles must be markedly weakened or paralyzed to produce claw deformity;
- long extensor muscles hyperextend the MCP joint, & long flexor muscles flex the PIP and DIP joints;
- weakness of the long flexors (as in high palsy) actually decreases claw fingers;
- PIP joint loses the ability to extend thru the
lateral bands and must rely on the
central slip;
- due to the anatomy of the saggital band, MP joint hyperextension blocks the the central slip from extending the PIP;
- hence, main force of contracted extensor mechanism is focused on saggital band, leading to further MCP hyperextension;
- tenodesis effect of extending the fingers w/ wrist flexion is lost;
- smooth flexion pattern is lost:
- normally, MP flexion initiates finger flexion, and all joint achieve full flexion nearly simultaneously;
- distal joint flexion is completed prior to initiation of MP joint flexion;
- hence, the fingers immediately come into contact w/ the palm w/ flexion;
-
causes:
-
combined low median and ulnar nerve lesions (may result in significant decreases in grip strength);
-
brachial plexus injuries;
- spinal cord injuries
-
Charcot-Marie-Tooth-Disease;
- Exam:
- w/ intrinsic weakness, the patient will demonstrate MCP hyper-extension and PIP flexion as he/see attempts to extend the digits;
- determine whether there is fixed PIP joint flexion contractures, especially in the ulnar fingers;
- w/ intrinsic weakness, PIP joint loses the ability to extend thru the
lateral bands and must rely on the
central slip;
- determine whether central slip is intact, by seeing if patient can extend PIP joint w/ MP joint held in flexion;
- Treatment: (Based on whether the Central Slip is Intact)
- central slip not intact:
- requires tendon transfers which pass volar to deep metacarpal transverse ligament, and are then attached to the
lateral bands;
- central slip intact:
- by preventing hyper-extension of the MP joints, extrinsic extensor muscles, will be able to extend DIP and PIP joints, thus preventing the claw deformity;
- orthotics (see
hand orthotics)
- dorsal knuckle bender or lumbrical bar;
- by holding the metacarpals in a slightly flexed position, the central slip can actively extend the PIP joint;
- creation of MPJ flexion contracture (may be performed by volar plate arthrplasty or tenodesis);
- Operative Correction:
- Burkhalter Transfer
- procedure of choice;
- Bunnell Transfer:
- involves FDS transfer to the lateral bands;
- interosseous &
lumbricals muscles of ring finger and little fingers, substituted by the
FDS of ring finger,
inorder to improve clawing and to improve flexion at the MP joint;
- first dorsal interosseous muscle substituted by
ECRL & split FDS of ring finger w/
one half to first
lumbrical & one half to first dorsal interosseous;
- half the tendon is passed dorsally thru the 1st interosseous, where as other half of the tendon is passed volarly to the lumbrical;
- main complication is creation of intrinsic plus hand, which preferentially extends PIP joint w/ minimal flexion of the MPJ;
- this is exacerbated by the PIP flexion lost from the FDS harvest;
- Zancolli Volar Capsulorraphy:
- performed thru a volar approach;
- goal is to create a MPJ flexion contracture, preventing claw deformity;
Clinical features of paralytic claw fingers.
One in four flexor digitorum superficialis
lasso for correction of the claw deformity.
Flexor digitorum superficialis tendon transfer for intrinsic replacement. Long-term results and the effect on donor fingers.
Restoration of Power Grip in Ulnar Nerve Paralysis.
WE Burkhalter MD
Orthopaedic Clinics of North America. Vol 5, No 2, Apr 1974. p 289.
Opponensplasty in intrinsic-muscle paralysis of the thumb in leprosy.
Paralytic claw hand: with special reference to paralysis in leprosy and treatment by the sublimis transfer of Stiles and Bunnell.
PW Brand.
JBJS. 1958. Vol 40-B. p 618.
Patterns of movement of totally intrinsic-minus fingers based on a study of one hundred and forty-one fingers.
Movement patterns of interosseus-minus fingers.
Tendon grafting: Illustrated by a new operation for intrinsic paralysis of the fingers.
PW Brand. JBJS Vol 43-B. p 444. 1961.
Abductor pollicis longus transfer for replacement of first dorsal interosseous.
Architectural design of the human intrinsic hand muscles.
