Good analgesia is crucial in fracture reduction. This can be achieved many different ways, including regional anesthesia, systemic pain medications, or procedural sedation.  For certain fracture types, such as wrist fractures, a hematoma block is often used.  Local anesthetic injected into the hematoma at the fracture site will diffuse through the hematoma to anesthetize periosteum and bone.

Numerous studies have shown simple hematoma blocks as safe and effective analgesia for reduction of fractures. It may also reduce length of stay over procedural sedation. 

Here we review the basic technique plus some tips/tricks for a successful hematoma block. 

Technique

- Clean skin, use aseptic technique

- Locate the fracture site/hematoma

- Insert the needle into the hematoma, and confirm appropriate positioning by aspirating blood

- Inject local anesthetic (ie 5-15cc 1% lidocaine) into the hematoma

- WAIT 5-10 minutes for appropriate analgesia

Tips/tricks:

- How to locate the fracture site/hematoma: often obvious by physical exam by locating a step-off, this isn’t always the case. It can be more difficult due to soft tissue swelling or body habitus or because of the type of fracture itself. Review x-rays before the procedure to help visualize. Also consider using ultrasound to locate the fracture and guide needle placement.

- Consider angle of needle entry: angling perpendicular to the skin or toward the fracture (ie, green arrows) will increase your chances of getting the needle tip into the hematoma at the fracture site. Angling the opposite way (red arrow) is less likely to be successful.

- If you don’t aspirate blood from the fracture site, this usually means you haven’t yet entered the hematoma yet – prematurely injecting your anesthetic will not achieve the desired results. You may need to adjust needle trajectory or site.

References:

1.  Tseng, P., Leu, T., Chen, Y. et al. “Hematoma block or procedural sedation and analgesia, which is the most effective method of anesthesia in reduction of displaced distal radius fracture?.” J Orthop Surg Res 13, 62 (2018). https://doi.org/10.1186/s13018-018-0772-7

2.  McGee, Douglas L. “Local and Topical Anesthesia.” Roberts and Hedges' Clinical Procedures in Emergency Medicine, by Jerris R. Hedges and James R. Roberts, 6th ed., Elsevier Saunders, Philadelphia, PA, PA, 2014, pp. 532–533.

3.  Fathi, M. et al. Ultrasound-guided hematoma block in distal radius fracture reduction: a randomized clinical trial. Emerg Med J. 2014 Jul 12.