Type I locking of the metacarpophalangeal joint: A case report.
BACKGROUND
Type I locking of the metacarpophalangeal joint (MCPJ) is rare and is characterized by loss of extension at the MCPJ with full flexion of all joints of the digit. The condition is usually seen in the index and middle fingers when the normal osseous prominence or degenerative osteophytes of the radial condyle of the metacarpal head catches the accessory collateral ligaments of the MCPJ.


METHODS
We report on a case of Type I locking of the MCPJ affecting the index finger. The case was unusual because it might have been related to repeated stress while opening caps of specimen bottles in the laboratory. Furthermore, the impingement of the radial condyle of the metacarpal was to the sesamoid bone, and not to the collateral ligaments of the MCPJ. Finally, management was done by excision of the sesamoid bone rather than trimming of the prominence of the radial condyle of the metacarpals head.


CONCLUSIONS
Locking of the metacarpophalangeal joint (MCPJ) should be viewed as two different entities: The "locked MCPJ with further flexion possible" (Type I locking) and the "locked MCPJ with further flexion not possible" (Type II locking). Once the type of MCPJ locking is diagnosed clinically, radiological testing (X-rays, CT scan, MRI) may be done to direct further management to the cause of locking.


CONCLUSIONS
We present an unusual case of Type I locking of the MCPJ affecting the index finger.
Division of Plastic Surgery at King Saud University, P.O. Box 18097, Riyadh 11415, Saudi Arabia. Electronic address: moqattan@hotmail.com.
Mohammad M
MM
Al-Qattan
Division of Plastic Surgery at King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.
Atif
A
Rafique
Joint; Locked; Metacarpophalangeal