A study of 221 claw fingers of fifty-one leprosy patients with ulnar or
combined ulnar and median-nerve paralysis showed that the severity of the
deformity was determined mostly by the completeness of paralysis of
intrinsci muscles, and to a lesser extent by the duration of paralysis.
There was no predilection for severe deformity in any one finger. Recurrent
dislocation of the extensor tendon from the knuckle of the
metacarpophalangeal joint was observed mostly in fingers that were
completely deprived of all intrinsic muscles. No satisfactory explanation
could be found for this. Flexing the wrist facilitated opening of the claw
finger, but the effect was more evident at the metacarphophalangeal joint
than at the proximal interphalangeal joint.