SIMULTANEOUS INTERPHALANGEAL DISLOCATION AND ULNAR COLLATERAL LIGAMENT RUPTURE OF METACARPOPHALANGEAL JOINT OF THE SAME THUMB

Singh HP

Abstract

Double dislocations of the thumb are rare. An unusual case of a simultaneous closed interphalangeal joint dislocation and ulnar collateral ligament rupture of the metacarpophalngeal joint of the thumb is reported. The patient had open repair of the collateral ligament and closed reduction of DIPJ with excellent postoperative recovery. The importance of careful assessment of hand injuries with stress test of the joints under local anaesthesia is reiterated.

CASE REPORT

A 47-year-old right-handed lady fell off her pushbike and injured her left hand. She attended A&E and was where the initial diagnosis of a closed dislocation of DIPJ and Scaphoid fracturef was made. She was given a thumb spica plaster after closed reduction of the dislocation. She was seen next day in Hand fracture clinic when she was found to be swollen and tender around the MCPJ of the thumb but not thought to have a Scaphoid injury.

She was re-examined under local anaesthetic injection to the digital nerves and stress tests revealed incompetence of her ulnar collateral ligament of the MCPJ of thumb.

Figure 1 Stress AP view of Thumb (indicating incompetence of ulnar collateral ligaments of both MCPJ and DIPJ)	Figure 2 Lateral view of Thumb (DIPJ subluxation)	Figure 3 Oblique view of Thumb

The ulnar collateral ligament was found to be incompetent so open repair of the ligament was performed under general anaesthetic. DIPJ was treated closed in the thumb spica plaster for six weeks after which she was allowed to mobilise the thumb freely under supervision of physiotherapists. She regained excellent function from her thumb although scar initially was a problem for her. It resolved with help of scar management regime with occupational therapy. The patient was discharged four months post surgery and had no limitation of activities after treatment of injury.

DISCUSSION

Ulnar collateral ligament rupture of the thumb is a relatively common injury that is often missed in the emergency department. This in combination with an interphalangeal joint dislocation of the ipsilateral thumb is rare and has been reported before. (1) The importance of use of local anaesthetic specifically to look for an associated ulnar collateral ligament laxity is stressed. The force producing a combination of ulnar collateral ligament rupture with ipsilateral simultaneous injury to the thumb is often severe enough to cause complete rupture of the ligament, necessitating open repair. (2,3) Careful clinical assessment of hand injuries and use of local anaesthetsia as an adjunct to diagnosis is reiterated. Local anaesthetic blocks are easy to perform and help to make accurate diagnosis especially for uncommon injuries and permitting appropriate management.

References

1) Ankarath S, Cohen AP. An uncommon injury of the thumb. Acta Orthop Belg. 2001 Feb; 67(1): 84-5.
2) Levy IM, Liberty S. Simultaneous dislocation of the interphalangeal and metacarpophalngeal joints of the thumb: a case report. J Hand Surg [Am]. 1979 Sep; 4(5): 489-90.
3) Lee JC, See HF, Low CO. Simultaneous open dislocations of the interphalangeal and metacarpo-phalangeal joints in a thumb--a case report. Singapore Med J. 1996 Jun; 37(3): 318-9.