MP Joint Locking


- Discussion:
    - index finger is most commonly involved, often found in older pts w/degenerative arthritis;
- Etiology:
    - muscular contracture or trauma;
    - collateral ligament or volar plate tethering on prominent MP head or osteophyte (on either side or volar aspect of metacarpal head);
    - torn palmar plate;
    - metacarpal head fracture;
    - loose body
    - abnormal sesamoids
- Diff Dx:
    - must be differentiated from Trigger Finger which is caused by stenosis of flexor tendon sheath in region of A1 pulley;
         - in Trigger Finger, catching characteristically occurs in PIP joint, where w/ "MP Locking", locking is in MP joint;
- Exam:
    - on exam, flexor tendons are intact, & active finger flexion may be nearly normal;
    - MP joint may not allow extension past  40 to 50 deg of MP flexion;
    - attempts to straighten the digit are painful;
- X-ray:
    - consider oblique x-rays of hand to demonstrate bony osteophyte


Locking of the metacarpophalangeal joint of the thumb.



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Thursday, October 4, 2012 2:21 pm