Acromioclavicular Joint Injection

Other Names

• Acromioclavicular Joint Injection
• AC Joint Injection
• AC Joint Arthrocentesis
• AC Joint Aspiration
• Acromioclavicular Joint Arthrocentesis

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Background

Illustration of the acromioclavicular joint

• This page refers to injections of the Acromioclavicular (AC) joint
  • This includes both injection and aspiration as the technique and approach are the same

Key Points

• Use high frequency, linear array transducer
• The joint is widest anteriorly

Anatomy

• Acromioclavicular Joint
  • Formed by the junction of the anteromedial acromion and lateral clavicle
  • Stabilized by the acromioclavicular, coracoclavicular ligaments
  • Allows for axial rotation, anterior posterior movement of the shoulder

Palpation vs Ultrasound Guidance

• Palpation guided accuracy is cited at 40% to 72% in the literature
• Ultrasound guidance has been shown to achieve an accuracy rate of 95% to 100%
• Outcomes between palpation and ultrasound guided injections were reported to be similar at up to 3 weeks post injection

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Aspiration

Ultrasound of normal AC joint in long axis

Indications

• Rule out Septic Arthritis
• Diagnose Gout or other spondyloarthropathy
• Symptomatic relief
• Unexplained joint effusion or monoarthritis

Contraindications

• Absolute
  • No absolute contraindications
• Relative
  • Abnormal or altered anatomy
  • Overlying infection or bacteremia
  • Coagulation
  • Prosthetic joint
  • Uncooperative patient
  • Diagnosis can be made with less invasive method

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Injection

Indications

• Acromioclavicular Joint Arthritis
• Acromioclavicular Joint Pain
• Osteolysis of distal clavicle

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

AC joint injection using out-of-plane technique

(a) Scheme and (b) ultrasound image of acromion–clavicular joint injection. Being inserted with co-axial, out-of-plane approach, only the needle tip (arrows) is visible. A, acromion; asterisk, joint capsule with synovial hypertrophy; C, clavicle.

Transducer orientation and needle position for an anterior approach, long axis to joint, needle out-of-plane

Transducer position and needle orientation for an anterior approach, transducer short axis to joint, needle in-plane.

Transducer position and needle orientation for a lateral approach, long-axis to joint, needle in-plane approach. Note the gel step-off technique.

AC joint injection using in-plane technique, lateral to medial approach

Equipment

• Sterile including chloraprep, chlorhexadine, iodine
• Ultrasound with sterile probe cover
• Gloves
• Needle: typically 25 gauge, 0.5-1 inch
• Syringe: 1-3 mL
• Gauze
• Ethyl Chloride
• Bandage
• Injectate
  • Local anesthetic
  • Corticosteroid

Ultrasound Findings

• Setup
  • Place ultrasound on opposite side of patient
  • Use high frequency linear transducer
• General
  • Best visualized in long axis, perpendicular to the joint line
  • Up to 3 mm of hypoechoic joint capsule can be considered normal
  • Intra-articular disc can be seen as a hypoechoic structure within the joint
• Common ultrasound findings
  • Cortical irregularities
  • Widening or instability of the joint (statically or dynamically)
  • Joint effusion with capsular distension
  • Ganglion cyst (so-called "Geyser sign"

Palpation Guided Technique

• Patient is in seated position
• Palpate medial acromion and distal clavicle.
• Mark site of injection with pen or impression
• Insert needle on superior aspect of skin between the medial acromion and distal clavicle
  • Needle may require subtle redirection to drop into joint space

Ultrasound Guided Technique: Long Axis, Out-of-Plane

• Patient position
  • The patient is seated, hand and shoulder in neutral
  • The physician is at the patients ipsilateral side, ultrasound across from them
• Transducer Position
  • Transducer is in coronal plane in long axis over the joint space
  • This can be done by finding the clavicle in long axis and moving the probe laterally
• Needle orientation
  • Inject the needle using the out-of-plane technique
• Needle approach
  • The entry point is perpendicular to the skin at the center of the probe
  • Use a step-wise approach to follow the needle tip dont into the joint space
• Pearls and Pitffals
  • Be certain to stop advancing as soon as the needle tip is visible in the joint space
  • Consider rotating the transducer 90 degrees during the procedure to confirm needle in position (using in-plane view)

Ultrasound Guided Technique: Short Axis, In-Plane, Anterior

• Patient position
  • The patient is seated, hand and shoulder in neutral
  • The physician is at the patients ipsilateral side, ultrasound across from them
• Transducer Position
  • Transducer is in sagital plane, long axis over the joint space
• Needle orientation
  • Inject the needle using the in-plane technique
• Needle approach
  • The entry point anterior, with an anterior to posterior trajectory
• Pearls and Pitfalls
  • Transducer may need to be tilted slightly to optimize visualization of the needle
  • Consider rotating the transducer 90 degrees during the procedure to confirm needle in position (using out-of-plane view)

Ultrasound Guided Technique: Long Axis, In-Plane, Lateral

• Patient position
  • The patient is seated, hand and shoulder in neutral
  • The physician is at the patients ipsilateral side, ultrasound across from them
• Transducer Position
  • Transducer is in coronal oblique plane, long axis over the joint space
• Needle orientation
  • Inject the needle using the in-plane technique
• Needle approach
  • The entry point lateral with a lateral to medial trajectory
• Pearls and Pitfalls
  • A gel step-off may be required to create a window for needle approach

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Aftercare

• Apply bandage
• No major restrictions in most cases
• Can augment with ice, NSAIDS

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Complications

• Pneumothorax
• Pain
• Infection
• Recurrence of effusion
• Damage to surrounding soft tissue structures

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See Also

• Procedures Main
• Ultrasound Main
• Shoulder Pain Main

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