Intended for healthcare professionals

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Practice Clinical Updates

Acquired triggering of the fingers and thumb in adults

BMJ 2017; 359 doi: https://doi.org/10.1136/bmj.j5285 (Published 30 November 2017) Cite this as: BMJ 2017;359:j5285

Rapid Response:

Alternative techniques for trigger digit steroid injection

The mid-lateral approach was described by Carlson and Curtis in 1984 [1]. Jianmongkol et al compared the mid-lateral approach with the conventional direct palmar approach in a prospective randomised control study of 103 trigger injections using a 2ml mixture of steroid and 1% lidocaine [2]. They demonstrated a 17% reduction in pain (8 points on a 100-point visual-analogue scale), with no difference in the consumption of post-procedure paracetamol. However, this difference in pain was lost quickly at first follow-up a week later, and recurrence of triggering beyond 6 weeks was not assessed. Within their study population, the mid-lateral approach appeared equally safe and effective, but the authors were keen to highlight the hazard of straying volar to the mid-axial line due to the associated risk of encountering the neurovascular bundle resulting in pain or damage even with a 25-gauge needle.

A further alternative method is a direct anterior, retrograde approach performed at the level of the proximal phalanx (P1), and is preferred by many ultrasonographers [3]. A prospective randomised control trial of 40 trigger injections using a 2ml mixture of steroid and local anaesthesia, demonstrated that a P1-level approach was as safe and effective as the conventional palmar approach, but with a 56% reduction in immediate pain (4 points on a 10-point visual-analogue scale) [4]. There was a trend towards higher recurrence of symptoms as early as 3 months, but this failed to reach statistical significance.

As is frequently the case in medicine and surgery, it is probably best to do what works well in your hands. I have found surgical and GP trainees become comfortable with the conventional palmar approach quickly. Physicians who wish to try the mid-lateral approach should follow the clear instructions set out by Mahaffey P (BMJ 2017;359:j5285/rr-0), and I have provided below some additional tips:

• Be aware that this approach introduces two planes of uncertainty, and triangulation is important not only for correct needle-tip position, but also to avoid neurovascular injury and subsequent distress. The importance of correct deposition of steroid within the flexor sheath has been questioned by Kazuki et al, who showed high success rates in resolving pain and triggering following injection of a mixture of steroid and 1% lidocaine into the subcutaneous tissue overlying the A1-pulley territory [5].
• It seems logical that higher gauge needles will be less painful, but ensure your unit stocks needles of correct length. The 25-gauge (orange) needles are available in both 15mm and 25mm lengths. 27-gauge (grey) needles are very fine but bend easily. Though a little more painful a 23-gauge needle may be better for larger hands with tougher palmar skin and tissue.
• A narrower needle will increase the resistance to flow (based on the Haigen-Poiseulle equation [6]), and greater force may be required to depress the syringe plunger. A small (<5ml) syringe with a one-piece luer-lock fitting [7] (as opposed to a slip-tip fitting) may prevent the embarrassing situation where the syringe disengages from the needle during injection, resulting in its contents splashing over both patient and physician!
• The evidence base behind trigger digit steroid injections advocates use of a mixture of steroid with 1% lidocaine [8,9]. There are presently no studies directly comparing trigger digit injections using steroid alone versus steroid mixed with a local anaesthesia agent. While combining local anaesthesia will not impact on the immediate pain experienced during an injection, it will be of benefit in reducing pain soon afterwards.

References
1. Carlson C, Curtis R, Steroid injection for flexor tenosynovitis, J Hand Surg Am. 1984; 9(2):286-7
2. Jianmongkol S, Kosuwon W, Thammaroj T, Intra-Tendon Sheath Injection for Trigger Finger: The Randomized Controlled Trial, Hand Surgery. 2007; 12(2):79–82
3. Bodor M, Flossman T, Ultrasound-guided first annular pulley injection for trigger finger, J Ultrasound Med. 2009; 28(6):737-43
4. Pataradool K, Proximal Phalanx Injection for Trigger Finger: Randomized Controlled Trial, Hand Surgery. 2011; 16(3):313-7
5. Kazuki K, Egi T, Okada M, Takaoka K, Clinical Outcome of Extrasynovial Steroid Injection for Trigger Finger, Hand Surgery. 2006; 11(1-2):1–4
6. Gooch J, Hagen-Poiseuille Equation, Encyclopedic Dictionary of Polymers. 2011, Springer, New York (NY)
7. International Organization for Standardization, ISO 80369-7 Small-bore connectors for liquids and gases in healthcare applications - part 7: connectors for intravascular or hypodermic applications, 1st Edition, 2016. URL: https://www.iso.org/standard/58011.html (last accessed 15 December 2017)
8. Mol MF, Neuhaus V, Becker SJ, Jupiter JB, Mudgal C, Ring D, Resolution and recurrence rates of idiopathic trigger finger after corticosteroid injection, Hand (N Y). 2013 Jun;8(2):183-90
9. Schubert C, Hui-Chou HG, See AP, Deune EG, Corticosteroid injection therapy for trigger finger or thumb: a retrospective review of 577 digits, Hand (N Y). 2013;8(4):439-44

Competing interests: No competing interests

17 December 2017
Michael C David
Post-CCT Senior Fellow in Hand Surgery
University Hospital Birmingham Queen Elizabeth
The Royal Town of Sutton Coldfield