UCL INJURY- THUMB

Description:
The ulnar collateral ligament provides stability to the MCP joint of the thumb in flexion and valgus.  It originates from the ulnar distal aspect of the first metacarpal and attaches onto the proximal ulnar portion of the proximal phalanx.   Injuries to the Ulnar Collateral Ligament can involve a sprain, tear and avulsion.    The UCL ligament is lax in extension and taught in flexion.  Tear can lead to pain with pinching grip. (1)  A complete rupture of the ulnar collateral ligament results in a stener lesion in 80% of cases. (2)  A stener lesion results in torn proximal ligament of UCL getting caught superficially over the aponeurosis of adductor pollicis (See Figure 2).  The separation of the proximal and distal ligament segments by the adductor aponeurosis prevents healing.
Figure 1 – Rupture of Ulnar Collateral Ligament of Thumb

Figure 2 – Adductor muscle insertion onto D1 Proximal phalanx that can obstruct proximal portion of UCL ligament

Injury Mechanism:  A valgus stress to the 1^st metatarsal phalangeal joint resulting in the stretching force to the ulnar collateral ligament of the joint.  This injury is known  presently as skier’s thumb, whereby the gripping of the the ski pole in between the thumb and index finger upon a fall onto the hand results in a valgus force with the pole as the fulcrum point for initiating the valgus force.  Historically occurred in gamekeeper’s gripping the necks of rabbits between thumb and forefinger, thus gamekeeper’s thumb.

Exam:  

Inspection – May notice swelling at the ulnar side of the MCP joint

Palpation – The ulnar side of the 1^st MCP joint will be tender

AROM – May be restricted due to effusion in joint but should be able to extend and flex against resistance.

PROM – Pain and apprehension may be present with flexion and extension of 1^st MCP as well as possible restriction due to effusion.

Special Tests – Valgus stressing of D1 MTP joint in 30 degrees of flexion (3,4)(see image) may reveal increased gapping of joint compared to opposite side as well as pain.  However due to pain in joint, gapping may not be present acutely. (5).

Neurovascular examination should be normal.

Investigations:

Xray – of D1 (thumb) – assess for fracture, avulsion of Ulnar collateral ligament.

US – of D1 (thumb) – assess for Stener Lesion.

MRI – If US inconclusive or not matching clinical impressions, MRI can provide a more definitive visualization of the UCL, adductor aponeurosis and evidence of boney edema from injury.

Management:

The initial management is to immobilize the first MCP in neutral position.  This can be done by thumb spica casting or splinting.

Partial injuries:  3-6 weeks (2,3,6)

Complete Rupture with Stener Lesions:  Require Surgical Repair (1-3)

Avulsion Fracture of base of proximal Phalanx:   May require surgical intervention if does not heal with immobilization.

Rehabilitation with range of motion and strengthening can begin at 4-6weeks depending on clinical assessment.

References: 

(1) Brukner P. Clinical sports medicine. Rev. 3rd ed. ed. Toronto: McGraw-Hill; 2009.

(2) Review of orthopaedics. 5th ed. ed. Philadelphia: Saunders / Elsevier; 2008.

(3) Eiff MP. Fracture management for primary care. 2nd ed. ed. Philadelphia: Saunders; 2003.

(4) Leversedge FJ. A pocketbook of hand and upper extremity anatomy: primus manus. 1st ed. ed. Philadelphia: Lippincott Williams & Wilkins; 2010.

(5) Chan K, Micheli L, Smith A, Rolf C, Bachl N, Frontera W, et al. F.I.M.S. Team Physician Manual. ; 2006. p. 14-15-32.

(6) Hand surgery. Philadelphia: Lippincott Williams & Wilkins; 2004.

Dr. Neil Dilworth CCFP Dip Sport Med  (April 30, 2014)