“I’m 0 for 2 tonight” your resident says after yet another exasperating interaction with one of your institution’s feisty surgery residents. “The first consult was called too early. The last one was called too late!” Overhearing your conversation, the charge nurse walks over and says, “Well Goldilocks, maybe this next consult with be just right…we just roomed a guy with a pretty gnarly arm laceration. Wanna go take a look?”
In the exam room you are confronted with an intoxicated and belligerent young man who is spitting at the tech trying to help hold pressure over his bleeding wound. The patient’s left forearm is bleeding profusely through the bandage the paramedics applied, and you notice shards of glass all over his clothing. Your resident approaches the patient with a balance of caution and confidence, learning that he locked himself out of his house and had to “break the window with his hand” to get in. The neighbors called the police when they heard the commotion, who in turn called EMS for his injured arm. The patient punctuates his answers with obscenities, shouting, “I can’t move my f---ing hand!” Your resident’s attempts to examine his bleeding extremity are met with more obscenities and the patient flailing his bleeding extremity.
You suspect that this guy might have an injury that will require operative intervention, but you also realize that your resident is going to need definitive, objective data to help appease the surgery resident taking consults. You pull your resident out of the room to discuss your management options. The patient is clearly not going to cooperate with the subtleties of a detailed neurovascular and tendon exam, and you doubt he’s going to tolerate a thorough wound exploration with local anesthetic alone. You don’t want to sedate the patient just to examine his wound, especially since he is already drunk, but you also don’t want to risk one of your staff getting hurt. You saw how he lashed out at the nurse who started his IV, and noted how he almost punched the X-ray tech, so you know your options are limited. Your patient is still refusing to flex his wrist or move his fingers, and you have to figure out if it’s because he can’t, or just won’t, before you chat with the surgical team.
As if she has read your mind, your resident calmly walks over to the sink and fills a basin full of water. She places the water basin in front of the patient and wheels over one of the department’s ultrasound machines. In a calming, yet firm tone, she tells the patient she needs to immerse his arm in the water basin to examine and clean out his wound. She promises “no needles” and bargains with a bit more IV morphine. In the water basin, you can see the patient has a large set of lacerations across his volar aspect of his distal forearm. Your resident floats the linear array transducer over the region of injury and carefully examines the flexor tendons near the forearm lacerations. She obtains the images below.
What do you see?
Conclusion on next page
Dx: Tendon Laceration
As your resident was scanning around the forearm, she picked up a laceration through the hyperechoic palmaris longus tendon (top) and lacerations through the flexor digitorum superficialis tendons (bottom). For good measure, she scans through the area a few more times in search of pieces of glass that might have been missed on his forearm X-ray. Satisfied with what you two see on the bedside ultrasound, you feel you have enough information to get your surgical colleagues down for a consult. If they require assistance with procedural sedation for an exploration and primary closure at bedside, at least you won’t have to sedate the patient twice, and you’ve minimized as much risk as you can for both the patient and your staff tonight.
The surgical team arrives in your ED; you watch with pride as your resident expertly summarizes the case and shows them her ultrasound findings. To your resident’s surprise, they opt to take the patient directly to the OR for definitive care, and thank her for a job well done. It looks like Goldilocks was able to win over the bear of surgical criticisms this night after all.
Pearls & Pitfalls for Ultrasound of Tendon Lacerations
1. It can often be difficult to determine whether tendon injury or disruption has occurred. On physical exam, normal function can be seen even with a 90% tendon disruption.
2. Ultrasound can augment clinical findings and help expedite the diagnosis, especially when the physical exam may be limited secondary to pain, swelling, or lack of patient cooperation.
3. If the target area is superficial, it is often useful to create your own acoustic window. Water immersion of the target structure can enhance visualization of superficial structures. Simply float the ultrasound probe in the water a few centimeters above the target structure. On your ultrasound screen, the acoustic layer of water will appear as a dark, anechoic line in the nearfield. The target structure will appear just farfield to this anechoic line.
4. Scan superficial structures with a high frequency (7.5 to 10 MHz) linear array transducer.
5. Begin by scanning in the longitudinal axis. Skeletal muscle will appear hypoechoic with interwoven echogenic striations and hyperechoic fascial planes. Adjacent tendons will appear brightly hyperechoic with visible linear fibers on long-axis scanning.
6. Any hypoechoic or anechoic interruption in the hyperechoic tendon fibers should raise the suspicion of a tendon disruption. The hypoechoic or anechoic area may represent blood or granulation tissue where the tendon fibers have torn apart. (Figures 3 & 4)
7. Subtle tendon damage may display an increase in the tendon cross-sectional area due to localized edema in the absence of actual tearing of the tendon fibers. Compare the area of interest to adjacent segments.
8. If the ultrasound beam is not aimed directly parallel to the tendon fibers, a false hypoechogenicity artifact may be noted (anisotropy). This artifact is most prominent in tendons that run in an oblique course and can occur when you are scanning near the insertion site. To avoid this error, make sure you obtain multiple views in two scanning planes.
9. With bedside ultrasound, you can often visualize both the proximal and distal ends of a complete tendon laceration, which are often difficult to find during beside exploration attempts.
Brady Pregerson manages a free on-line EM Ultrasound Image Library and is the editor of the Emergency Medicine Pocketbook series. www.EMresource.ORG
Teresa S. Wu is the Associate Residency Director, and Director of Ultrasound and Simulation Based Training for the Maricopa Emergency Medicine Program in Phoenix, Arizona.