Thumb Ligament Injuries

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Clinical Relevant Anatomy

The thumb MCP is similar in anatomical appearance to those of the finger,but essentially functions as a hinge or ginglymus joints. The articular morphology found in this joint makes it the most varied motion of all joints, with range of motion of 6 to 86 degree in flexion-extension.

• flexor pollicis brevis (FBP)
• Abductor pollicis brevis (APB) muscles insert partially on the sesamoids and provide stability against hyperextension forces.

The ligamentous anatomy is analogous to that seen in the finger MCP joints, with extrinsic tendons providing additional support

Mechanism of Injury / Pathological Process

The Metacarpophalangeal (MCP) joint of the thumb are stabilize by two major ligaments. The ulnar collateral ligament (UCL) and the Radial collateral ligament (RCL) . The UCL is more commonly injured, usually from forced radial deviation (abduction) of the thumb, while the RCL are rarely injuried. However, in severe type of injuries, both ligaments may be ruptured.

Clinical Presentation

add text here relating to the clinical presentatio

Diagnostic Procedures

History taking, including mechanism, finger position during injury, the presence of deformity, previous treatment received, and subjective sense of stability of the injured thumb.

• Neurovascular exam must determine motor function, perfusion, and

sensation.

• Weakness with pinch function usually exists in ligament ruptures.

• Examine the base of the thumb for ligamentous laxity and compare it

to the uninjured hand:

• Examine the thumb with 20–30* of flexion.

• Carefully abduct the thumb passively and compare the angle of

deviation to the uninjured thumb.

• An angulation of >30* on the injured thumb or >15* compared to

the uninjured thumb is diagnostic for a ligamentous injury.

• Radiography should be obtained to assess for the presence of a Stener's lesion or a fracture fragment.

•further assessment of joint should be performed using a digital block may be necessary to complete a full examination

because of pain and swelling in the acute setting

Outcome Measures

add links to outcome measures here (see Outcome Measures Database)

Management / Interventions

A thumb spica splint or cast immobilization is indicated for 4 weeks for

a partial rupture, or up to 6 weeks if an associated avulsion fracture is

present.

For acute injury

• Rest, elevation, ice

• Immobilization in a thumb spica splint

• Analgesics

• Orthopedic follow-up

For chronic injury

• Thumb spica brace

• Activity modifi cation

• Orthopedic surgery consultation for elective ligament repair or

reconstruction may be necessary with a complete rupture.

Physical or occupational therapy is helpful postoperatively to increase

range of motion and strength, and to assist in resuming activities

Differential Diagnosis

• First metacarpal or proximal phalanx fractures

• First CMC joint arthritis

• Volar plate injury

Resources

add appropriate resources here