MCQs – Hand 1

MCQs-Hand 1
MCQs-Hand
The most common cause of ulnar tunnel syndrome is a ganglion; other soft tissue masses can occur. Beware fractures of the wrist or hook of hamate, repetitive trauma, ulnar artery thrombosis, pseudoaneurysms.

Radial shortening in a Colles fracture is particularly bad for rotation. In general, shortening on the MCQ exam seems to be the worst prognosistic factor in Colles fractures; worse than abit of angulation. Dorsal articular angulation decreases motion, but above 10 degrees of dorsal angulation is also painful. Shortening of 2 mm increases the risk of radiocarpal arthrosis by 20%.

Dorsal angulation of the distal radius fracture decreases the contact area of the distal articular surface for the scaphoid and lunate. This and shortening can lead to arthritis. Shortening of the radius tends to cause more ulnar loading and can lead to ulnocarpal impingement and subsequent arthrosis.

Radial shortening and shift is associated with decreased grip strength, while dorsal angulation is more associated with decreased ROM.

Silicone arthroplasty is preferred over fusion for MCP involvement in the rheumatoid hand.

Joints that must be stable to provide strong lateral pinch are more amenable to fusion in the rheumatoid hand – eg: PIP joints of long and index fingers, and the thumb MCP and IP.

Joints that have motion which is important for hand function/dexterity do poorly with fusion – eg: PIP of ring and small fingers, and the CMC joint of the thumb. Ie. Try to avoid fusing the PIP joints of 4 and 5.

Active extension of the PIP joint is the key test to perform when ruling out acute Boutonniere deformity. A 15 to 20 degree or greater loss of active PIP extension when the wrist and MP joint are fully flexed is a sign of potential central slip disruption. Weak PIP extension against resistance is also suggestive. Extravasation of intra-articular dye dorsal and distal to the PIP joint is also diagnostic.

Condylar fractures of the metacarpals and phalanges require closed reduction and pinning or open reduction and internal fixation if the closed reduction is inadequate. They are not stable if left alone, even if undisplaced.

Beware quadriga effect in traumatic amputations of the finger – if the FDP tendon is sewed down or over the tip to the extensor tendon, that finger may flex fully, but it will reach the end of its flexion before the other fingers have fully flexed. Because there is no more flexion possible in that finger, and because they all come from one muscle belly, the rest of the fingers now will not achieve full flexion. If you see this in the amputated finger, go in and release the FDP tendon to that finger.

A finger that goes out straight when attempting to flex it is demonstrating the “lumbrical plus” phenomenon. It occurs when the pull of FDP is applied through the lumbrical, so that the MCP joint is flexed, but the DIP and PIP joints are extended when a forceful flexion is attempted. This is seen in FDP tendon grafts, and in amputations through the middle phalanx. Treatment is to transect the involved lumbrical tendon through a longitudinal incision in the webspace, on the radial side of the finger.

Volar dislocations of the PIP joint cause central slip avulsions

Wrist arthrodesis – best fusion position: 10-20 of dorsiflexion, 5-10 of ulnar deviation, with 3rd metacarpal lined up with the radius.

Triggering of the finger occurs with stenosis at the A1 pulley – located just at the MCP joint.

Gameskeeper thumb injuries (ulnar collateral ligament) – interposition of the adductor aponeurosis (Stener lesion) is the reason to explore and fix these injuries early.

Test the UCL of the thumb in 30 of flexion – tests the main collateral ligaments.

In UCL injuries, the fragment of bone that may get pulled off is from the proximal phalanx, not the metacarpal.

Do not immobilize a gameskeeper thumb injury/repair with the thumb metacarpal in adduction. This is not written anywhere, but I can’t imagine how this protects the repair. In addition,

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