Carpometacarpal Joint Injection

Other Names

• CMC Joint Injection
• Thumb CMC Joint Injection
• CMCJ Injection
• First carpometacarpal joint injection

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Background

Labeled radiograph PA radiograph of the wrist

Key Points

• This page refers to injection of the Carpometacarpal Joint of the thumb
• This injection can be performed with or without ultrasound, although we recommend ultrasound
• Use a 25 gauge, 1.5 inch needle
• Transducer: high frequency linear array
• Dorsal approach is optimal
• Be careful to avoid the neurovascular bundle

Anatomy of the Carpometacarpal Joint

• Thumb CMC Joint
  • Also called the trapeziometacarpal joint
  • Characterized by the articular of the 1st Metacarpal and Trapezium
• Radial artery and radial nerve run along the volar surface
• Abductor pollicis longus, extensor pollicis brevis run along the radial side
• Anatomic snuff box
  • Radial: APL, EPB
  • Dorsal: ECR, EPL
  • Floor: Trapezium
  • Anterior: 1st metacarpal

Palpation Guidance vs Ultrasound Guidance

• Smith et al found palpation guided injections were 80% accurate while ultrasound guided injections were 100% accurate
• Derian et al, using a novel assessment scale, found no difference between ultrasound and palpation guidance in a cadaveric study
• Philip et al found palpation guidance had an accuracy of only 63%, that ultrasound improved accuracy but this was dependent on user experience
• Katt et al found palpation guidance to be only 80% accurate

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Indications

• Carpometacarpal Joint Arthritis

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Contraindications

• Absolute
  • Anaphylaxis to injectates
  • Overlying cellulitis, skin lesion or systemic infection
• Relative
  • Can be treated with less invasive means
  • Hyperglycemia or poorly controlled diabetes
  • Lack of symptom improvement with previous injection

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Procedure

Demonstration of palpation guided injection

Needle and probe position for in plane approach

Ultrasound view for in-plane technique with needle (arow) trajectory.

Needle and probe position for out of plane technique

Ultrasound view for out of plane technique with needle (white dots) marking the trajectory

a, b Illustration (a) and long-axis US image (b) demonstrate the in-plane approach with the transducer (blue rectangle in A) perpendicular to the joint and the needle (arrows in B) inserted from a proximal to distal direction

Equipment

• Sterile including chloraprep, chlorhexadine, iodine
• Gloves
• Needle: typically 25 to 27 gauge, 0.5 to 1.0 inch
• Syringe: 1-3 mL
• Gauze
• Ethyl Chloride
• Bandage
• Injectate
  • Local anesthetic
  • Corticosteroid

Ultrasound Findings

• Use a high frequency, linear probe
• Common findings:
  • Enlarged triangular joint space
  • Cortical irregularities
  • Erosions seen in inflammatory arthropathies
  • Effusion

Technique: Palpation Guided

• Patient Position
  • The patient should be seated, alternatively they can be supine
  • Hand should be resting on the examination table
  • Radial side is up or superior, ulnar side resting on the table
• Needle Orientation and Approach
  • Proximal to distal
• Description
  • Palpate the small space between the trapezium and first metacarpal dorsally
  • Use the anatomic snuffbox for medial and lateral borders
  • Between the 1st and 2nd dorsal compartment
  • Mark this space with a pen or other blunt object
  • Sterilize the marked skin
  • Inject the needle into the joint space
  • Angle should be about 45° degrees to the skin
  • You should feel it "drop in" to the space
  • You may have to redirect cranial or caudal in small increments to achieve this
• Pearls and Pitfalls
  • An assistant or the proceduralist should apply traction on the distal thumb to further open the joint space
  • Aspirate to make sure you aren't in a vessel prior to injection

Ultrasound Guided In-Plane

• Patient position
  • Patient is seated or supine
  • Hand placed on table with ulnar sidse down, radial side up
• Transducer position
  • Over the anatomic snuff box
  • Aligned with the long axis of the carpometacarpal joint
• Needle Orientation and Approach
  • In Plane
  • Stand off oblique technique
• Target
  • CMC joint space
• Pearls and Pitfalls
  • Be careful to avoid the neurovascular bundle
  • Joint space is characterized by the "seagull" appearance of the carpal and metacarpal reflection

Ultrasound Guided Out-of-Plane

• Patient position
  • Patient is seated or supine
  • Hand placed on table with ulnar sidse down, radial side up
• Transducer position
  • Over the anatomic snuff box
  • Aligned with the long axis of the carpometacarpal joint
• Needle Orientation and Approach
  • Out of Plane
  • Step-wise technique
• Target
  • CMC joint space
• Pearls and Pitfalls
  • See above

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Aftercare

• No significant restrictions
• Can augment with ice, NSAIDS
• Consider placement in a Thumb Spica Splint

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Complications

• Skin: Subcutaneus fat atrophy, skin atrophy, skin depigmentation
• Painful local reaction
• Infection
• Hyperglycmia
• Tendon, nerve or blood vessel injury

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See Also

• Procedures Main
• Ultrasound Main
• Hand Pain Main

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