Persistent Thumb Metacarpophalangeal Joint Instability after Trivial Trauma

We present this unique case that has not been addressed adequately in the literature. A 42-year-old African–American male presented to the hand center for evaluation of a 4-month left thumb injury.

On physical examination, the thumb metacarpophalangeal (MCP) joint demonstrated increased laxity to varus stress and tenderness over the radial collateral ligament (RCL). X-ray and an MRI was ordered for radiographic correlation. An X-ray demonstrated volar subluxation of the first MCP joint [Fig. 1]. MRI investigation demonstrated complete tear with retraction of the radial collateral ligament and a tear of the ulnar collateral ligament (UCL) without evidence of a Stenar lesion [Fig. 2].

Fig. 1 X-ray: Volar subluxation of the 1st MCP joint. MCP, metacarpophalangeal.

Fig. 2 MRI: Full-thickness tear of the UCL. The UCL is avulsed off the proximal phalanx, but remains at its insertion. No evidence of Stenar lesion apparent. UCL, ulnar collateral ligament.

After a failure of conservative treatment and persistent varus instability, we proceeded with surgical repair of the RCL because it was retracted and the thumb was unstable to varus stress. We chose to treat the UCL conservatively given there was no evidence of a Stenar lesion. The procedure was completed local with sedation. A lazy S incision was made on the radial aspect of the thumb MCP joint. A 2.7 mm titanium anchor was used for fixation of the RCL into the metacarpal head.

Thumb instability due to unilateral collateral ligament injuries are frequent complaints that physicians will encounter. Combined RCL and UCL injuries are rare occurrences. They have been reported by Brian et al in adults involved in high-contact sports activities. This text concluded that combined UCL and RCL ligamentous injuries in the National Football League were a frequently undescribed and underdiagnosed injury.[1] They proposed that any patient presenting with an isolated ligamentous injury should have the contralateral ligament assessed for injury.[1] If combined injuries are present, they should be treated with surgical intervention.[1] Combined ligamentous injuries were also reported by Bhat et al, in which an adolescent sustained two separate injuries while playing volleyball and badminton.[2] The patient was initially managed conservatively; however, after 2 months without symptomatic improvement, delayed primary repair was chosen over reconstruction; the collateral ligaments were anatomically repaired using 1.8 mm suture anchors.[2]

The literature is limited regarding this rare injury; these two references do not describe an algorithm for the management of combined injuries. To our knowledge, our case report is the first of a combined thumb MCP collateral ligament injury due to an isolated traumatic event. We believe there is not adequate data to develop an algorithmic approach to combined RCL/UCL thumb injuries.

Our goal is to prompt discussion with regard to the role of surgical intervention for combined thumb RCL/UCL injuries. We chose surgical intervention in this scenario, given a variety of factors–the proximal phalanx subluxation on the metacarpal head, physical examination demonstrated instability to varus stress and, most importantly, the patient had failed a course of conservative treatment. With combined thumb MCP UCL and RCL injuries, physical examination and imaging are paramount and will help dictate management.

Publication History

Article published online:
28 June 2020

• References

• 1 Werner BC, Belkin NS, Kennelly S. et al. Injuries to the Collateral Ligaments of the Metacarpophalangeal Joint of the Thumb, Including Simultaneous Combined Thumb Ulnar and Radial Collateral Ligament Injuries, in National Football League Athletes. Am J Sports Med 2017; 45 (01) 195-200
• 2 Bhat AK, Mane PP, Acharya A, Madi S. Simultaneous combined complete tear of radial and ulnar collateral ligaments of thumb in an adolescent. BMJ Case Rep 2017; 2017: bcr-2017-220550