thumb and test volar-dorsal translation of the distal ulna at different rotations
TFCC load test
– hold the wrist in ulnar deviation, apply axial load. Passive manipulation of the carpus against the ulna and rotation will produce painful crepitus.
Begins with inspection
– results from loss of intrinsic muscle action and the overaction of the extrinsic extensor muscles on the proximal phalanx. In general, the intrinsics act to flex the MCPs, and can extend the PIPs and DIPs. In this deformity, the MCPs are hyperextended, and the PIPs and DIPs are flexed. This is called the “intrinsic minus” hand. Note that the extensor communis is not able to extend the PIP and DIP joints with the MCP extended (all the force of the extensor pull is taken up by the sagittal bands and extensor hood to extend the MCP).
– This results from combined median and ulnar nerve palsies, such that all the intrinsics are affected. Look also for wasting of the thenar and hypothenar eminences, and the first webspace.
– wasting of the hypothenar muscles of the hand, the interossei (particularly the first dorsal interosseous), and the two medial lumbrical muscles from a low ulnar nerve palsy. (Remember that in a high ulnar nerve palsy, the deep flexors are also paralyzed and so the clawing is usually absent.)
– basically, the ulnar two digits are “clawed”, with hyperextended MCPs, and flexed DIP/PIPs. The lumbricals of the index and long fingers usually compensate to a certain degree so that there is less hyperextension at the MCP and less flexion of the DIP/PIP.
– wasting of the thenar eminence and the thumb falls back in line with the fingers due to the pull of the extensor muscles.
– This results from a median nerve palsy.
Functional Motor Tests
– abductor pollicis brevis function
Anterior Interosseous Nerve
– flexor pollicis longus function
– note the pinch attitude of AIN palsy
– abductor digiti minimi
– first dorsal interosseous
– adductor pollicis – Froment’s sign
– characteristic wrist drop
Posterior Interosseous Nerve
– ability to extend the MCP joints beyond 45o (EDC), and ability to retroposition the thumb to the plane of the other metacarpals (EPL/APB).
– dynamic two point discrimination