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Trigger Point Injection

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Other Names

  • Stenosing Tenosynovitis at the First Annular Pulley Injection
  • Trigger Point Injection

Background

Anatomical landmarks with needle entry point.[1]

Key Points

  • Needle: 25-30 gauge, 1.5 inch
  • Transducer: high frequency, linear
  • In plane, out of plane or palpation guidance is appropriate

Anatomy of the A1 Pulley of the Hand

  • Arises from the volar plate of the metacarpophalangeal joint
  • Average length is 1 cm[2]
  • Proximal crease of the hand can be used as a surface marker
  • Proximal edge of A1 pulley lies ~1.5-2 cm from proximal finger crease
  • Distal edge of A1 pulley lies approximately 1 cm from proximal finger crease

Ultrasound Guidance vs Palpation Guidance

  • Lee et al showed ultrasound guidance[3]
    • Improved needle placement accuracy
    • Enhanced safety in avoidance of neurovascular structures
    • Potential increased efficacy by more precise placement of steroid to the desired target
  • Tuncez et al compared ultrasound guided vs blinded trigger finger injections[4]
    • Patients in the US group did better at 1st and 4th week
    • There was no difference at 12th or 24th week

Indications


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

Procedure

Long axis, in plane technique with needle and probe position[5]
Pre- and post-injection ultrasound images of the 3D-printed phantom compared to a human finger, with all relevant anatomical features labelled. A) Finger phantom with all relevant labels; B) needle approaching injection location; C) injection into location; D) phantom model post-injection with injectate and separation; E) human model pre-injection; F) human model post-injection with injectate and separation. A1: first annular; FDC: flexor digitorum communis; MC: metacarpal.[6]
Short axis, in plane technique with needle and probe position[5]
Short axis, in plane technique with ultrasound view and needle pictured[5]
(A) Short axis, out of plane technique with needle and probe position. (B) Needle trajectory (white arrow) with labels A1 pulley (arrowheads), neurovascular bundle (NV), FDS and FDP, volar plate (VP) and metacarpal (M)[7]
(A) Palpitate the metacarpal neck. (B) With the affected finger in a flexed position, insert a 26-gauge needle aiming at 45°. (C) Ask the patient to flex and extend the finger to ascertain that the needle tip is not in the tendon. (D) Inject and feel the fluid thrill.[8]
Illustration of the proximal phalanx intra-sheath approach

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

  • Use a high frequency, linear transducer
  • Tenosynovitis
    • Hypoechoic layer around the flexor tendon
    • Enlargement of the tendon and sheath just distal to A1 pulley
  • A1 Pulley
    • Identified as a thin hypoechoic line volar to the flexor tendon
    • At/ just proximal to the MCP joint
  • Dynamic ultrasound
    • Can be used to view the bunching/catching of tendon
  • Identify digital nerves and vessels to determine appropriate entry

Technique: Long Axis, In Plane

  • Patient position
    • Seated or supine
    • Wrist is supinated and flat on table
  • Transducer position
    • Long axis to flexor tendon, A1 pulley
  • Needle Approach/ Orientation
    • In-plane
    • Distal to Proximal/ Proximal to distal
  • Target
    • Between A1 pulley and flexor tendons
  • Pearls and Pitfalls
    • Rotating to short axis view can confirm central positioning of needle
    • Consider "stretch release" procedure
    • Technique is the same for thumb

Technique: Short Axis, In Plane

  • Patient position
    • Seated or supine
    • Wrist is supinated and flat on table
  • Transducer position
    • Short axis to flexor tendon, A1 pulley
  • Needle Approach/ Orientation
    • In-plane
    • Ulnar to radial/ radial to ulnar
  • Target
    • Between A1 pulley and flexor tendons
  • Pearls and Pitfalls
    • Technique is the same for thumb

Technique: Short Axis, Out of Plane

  • Patient position
    • Seated or supine
    • Wrist is supinated and flat on table
  • Transducer position
    • Short axis to flexor tendon, A1 pulley
  • Needle Approach/ Orientation
    • Out of plane
    • Distal to proximal
  • Target
    • Between A1 pulley and flexor tendons
  • Pearls and Pitfalls
    • Technique is the same for thumb

Palpation Guided Technique: Classical Approach

  • Patient position
    • Seated or supine
    • Wrist is supinated and flat on table
  • Palpate the flexor sheath and mark the entry point
    • The S1 pulley is tender and nodular
    • This is ~1 cm proximal to the proximal finger crease
  • Mark the skin
  • Sterile prep
  • Insert needle at approximately 45°
    • This can be proximal to distal or distal to proximal
  • Aim to inject superficial to sheath
    • You will know you are in the right spot when the injectate flows freely
    • Never inject against resistance

Palpation Guided: Proximal Phalanx Intra-Sheath Injection

  • Description
    • Injection site is at the A2 pulley on the proximal phalanx
    • Thought to be less painful than classical technique
  • Patient position
    • Seated or supine
    • Wrist is supinated and flat on table
  • Mark the injection site
    • Site is the central proximal phalangeal flexor crease
    • This is distal to the A1 pulley
  • Mark the skin
  • Sterile prep
  • Insert needle at approximately 45
    • This can be proximal to distal or distal to proximal
    • Aim to inject superficial to sheath
  • Pearls and Pitfalls

Aftercare

  • No significant restrictions
  • Can augment with ice, NSAIDS

Complications

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

See Also


References

  1. Zhong, Wei-xing, et al. "Identification of the length and location of the A1 pulley combining palpation technique with palm landmarks: a cadaveric study." Scientific Reports 13.1 (2023): 22801.
  2. Florini HJ, Santos JBG, Kirakaw CK, et al. Anatomical study of the a1 pulley: length and location by means of cutaneous landmarks on the palmar surface. J Hand Surg. March 2011;36(3):464–468.
  3. Lee DH, Han SB, Park JW, et al. Sonographically guided tendon sheath injections are more accurate than blind injections: implications for trigger finger treatment. J Ultrasound Med. 2011 Feb;30(2):197–203.
  4. Tunçez, Mahmut, et al. "Ultrasound guided versus blinded injection in trigger finger treatment: a prospective controlled study." Journal of Orthopaedic Surgery and Research 18.1 (2023): 459.
  5. 5.0 5.1 5.2 Malanga, Gerard A., and Kenneth R. Mautner. "Atlas of ultrasound-guided musculoskeletal injections." (No Title) (2014)
  6. Willis, Joseph Gartrell, James Barrett Harris, and Jordan Austin. "An ultrasound phantom for stenosing flexor tenosynovitis." RADIOLOGY (2021).
  7. Image courtesy of nysora, "ultrasound guided hand and wrist injections
  8. Ko, Sang Hyun, Dong Eun Kim, and Tong Joo Lee. "Steroid injection using tendon excursion for trigger finger: introduction to injection methods and analysis of treatment results." Archives of Hand and Microsurgery 27.1 (2022): 33-40.
Created by:
Jesse Fodero on 10 July 2019 19:03:56
Authors:
Last edited:
20 June 2024 18:35:07
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