Claw hand deformity def, types, Symptoms, Clinical tests, Treatment.

 It is a deformity with hyperextension of the metacarpophalangeal joints and flexion of the interphalangeal joints of the fingers.

Types and Causes:

• two varieties are described: one is a true claw hand involving both median and ulnar nerves(Syringomyelia, muscle atrophy, leprosy, peripheral neuritis, anterior poliomyelitis etc.,)
•  the second an ulnar claw hand or claw-like hand ( here only ulnar nerve is involved) due to ulnar nerve injury

Clinical features:-these include the classical deformity

• loss of sensation along the ulnar nerve distribution 
• wasting of the hypothenar muscles
• intrinsic muscles of the hand leading to hallow intermetacarpal spaces on the dorsum of the hand 
• if high lesions above the level of elbow entire nerve function is lost
• however the clinical features vary depending upon the level of lesion.

Clinical tests:-for ulnar nerve injury

Froment's sign :-

Three muscles (first palmar interossei, adductor pollicis and flexor pollicis longus) are required to hold a book between the thumb and other fingers, In ulnar nerve injury the first two muscles are paralyzed  and now to hold the book, patient has to depend only on flexor pollicis longus with flexes the thumb prominently. This is the positive Froment's sign.

Card test:-

Inability to hold a card or paper in between fingers due to loss of abduction by the palmar interossei.

Egawa test:-

With palm flat on the table the patient is asked to move the middle finger sideways. This is a test for the dorsal interossei of middle finger.

Pen test:-

Patient is unable to touch the pen due to loss of action of abductor pollicis brevis.

Pointing index or Oschner's clasp test:-

both the hands are clasped together, index and middle fingers, fail to flex due to loss of action of the long finger flexors of the index and middle fingers which are supplied by the median nerve.

Benediction test:-

for the same reason mentioned above patient is unable to flex the index and middle finger on lifting the hand ( this is the position a clergyman uses to bless Aa couple during marriage.)

Investigation:-

Plain radiography of affected area and other investigations like EMG,SD curve, nerve conduction studies, Tinel sign etc., are carried out

Treatment :-

In acute injuries - The treatment is as discussed in the general principles

For claw hand deformity

Principles of treatment All the treatment measures aim at blocking the hyperextension at the metacarpophalangeal joint. Once this joint is stabilized the long extensors will bring about the extension of IP joints. The long finger flexors will help in flexion of the MP joints along with their action of finger and wrist flexion.

Methods of Stabilization of MP joints

This can be done by the active method which involves tendon transfer or by passive method which involves arthrodesis, capsulodesis or tenodesis.

Active method

This is by tendon transfer. A neighboring healthy tendon is brought to replace the action of the lost intrinsic. The choice of the tendon is dictated by the available normal tendons and the existing local situations. Whichever the tendon chosen, it is passed through the lumbrical canal and is attached to the dorsal digital expansion which then brings about the action of the intrinsic. Before resorting to tendo transfers, certain criteria are to be followed.