Metatarsosesamoid Joint Injection

Other Names

• Metatarsosesamoid Joint Injection

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Background

PA radiograph of the foot showing the medial and lateral sesamoids

Key Points

• Transducer: high frequency, linear array
• Needle: 25-27 gauge, 1 inch needle

Anatomy of the Hallux Sesamoids

• Located at the first metatarsal head, within the medial and lateral bands of the flexor hallucis brevis tendon
• Abductor hallucis and Adductor hallucis tendons insert on the lateral and medial sesamoids respectively
• Stabilized by the deep transverse metatarsal, intersesamoid and medial and lateral collateral ligaments
• There is a small bursa located directly beneath each sesamoid
• Functions to elevate first metatarsal head, transmit weight through forefoot, improve mechanical advantage in toe flexion

Palpation Guidance vs Ultrasound Guidance

• Reach et al had a 100% success rate with ultrasound guided injections
• Balint et al compared US guided vs palpation guided injections, finding 97% with ultrasound and 32% with unguided approach
• Raza et al found 59% accuracy with palpation guided injections versus 96% with ultrasound guided injections

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Indications

• Sesamoiditis

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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

In-plane, medial plantar needle approach to the first metatarsosesamoid joint

Short-axis imaging over the metatarsosesamoid joint of great toe shows tibial sesamoid medially (open arrow), fibular sesamoid laterally (open arrow), and metatarsal head (thin arrow). Medial is to the right side of the image.

Short-axis imaging over the metatarsosesamoid (MTS) joint of great toe shows the needle tip (thin arrow) clearing the tibial sesamoid and entering the MTS joint space (asterisk). Medial is to the right side of the image

Equipment

• Sterile prep (i.e. chloraprep, chlorhexidine, iodine, etc)
• Gloves
• Needle: typically 21-25 gauge, 1.5 inch
• Syringe: 5-10 mL
• Gauze
• Ethyl Chloride
• Bandage
• Injectate
  • Local anesthetic
  • Corticosteroid
• Sterile probe cover

Ultrasound Findings

• Optimal setup
  • Transducer: high frequency, linear array
  • Best visualized in short axis
  • Depth of less than 1 cm
• Common findings
  • Cortical irregularities
  • Calcifications
  • Effusions
• Bipartite or multipartite sesamoids are also commonly seen

Ultrasound Guided Technique: Short Axis, In Plane

• Patient Position
  • The patient is supine or in lateral decubitus position
  • Foot laying on the lateral side with medial foot pointed up
• Transducer Position
  • Short axis over the first metatarsal head
• Needle Approach/ Orientation
  • In plane
  • Medial to lateral
• Target
  • Either bursae or metatarsosesamoid joint
• Pearls and Pitfalls
  • Consider 1st MTPJ injection unless peri-sesamoid soft tissue injection indicated
  • Avoid the FHB, abductor hallucis, adductor hallucis tendons

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Aftercare

• Motor exam should be intact
• No major restrictions in most cases
• Can augment with ice, NSAIDS

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Complications

• Infection
• Damage to surrounding tissue

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See Also

Internal

• Procedures Main
• Foot And Ankle Anatomy
• Physical Exam Foot
• Foot Pain Main

External

• https://www.sportsmedreview.com/blog/performing-an-ultrasound-guided-first-mtp-joint-injection/

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