Soundings: Do you need to call Hand?

The unmistakable sounds of nursing shift change roar through the department. Your department’s choice to transition over to electronic orders and charting was welcomed by furrowed brows and a steady flow of four-letter exclamations from those who are still struggling to hunt and peck their way into our technologically advanced era.

You walk over to one of your interns who has been trying for over 15 minutes to calm a screaming 24-year-old construction worker. He was attempting to splice some electrical wires with a box cutter when the blade slipped and sliced through the thenar eminence of his non-dominant hand. You stand at the doorway listening to your intern explain the plan to anesthetize the wound for irrigation and exploration prior to repair. Her calming tone is met with “Are you crazy, lady? I’m not letting you near me with any needles. My hand already hurts like a son-of-a-bitch and you want to stick a needle in it?!” You’re always amazed by the inverse relationship between the size of a man’s biceps and his tolerance to pain.

You know it’s going to take quite a bit of TLC and a lot of your intern’s precious time and patience to determine if the patient has a tendon injury that your hand surgeon may want to operate on that night. You deem that the patient has not suffered any catastrophic vascular injury and it would be nice to assess the flexor pollicis longus and call in the consult before your favorite hand specialist screeches home in his machismo Lamborghini. You know that if you wait too long to call and you end up waking him up at home, the expletives from your patient will seem genteel in comparison. The last time you called a consult to this guy, your pleas for him to do his job were rewarded with him yelling at the top of his lungs “This is physician abuse!!”

You wheel your trusty ultrasound machine into the patient’s room and make your own acoustic standoff pad with a saline-filled glove (stay tuned to learn how to do this in a future article). Within a few minutes, you obtain these ultrasound images of your patient’s hand tendons underneath the laceration. Is there any sign of tendon injury on ultrasound?

On ultrasound, you are able to clearly visualize the hypoechoic skeletal muscle surrounding the brightly hyperechoic tendons. As you scan along the tendon in a longitudinal plane, all of the tendon fibers appear intact. You note that there is absence of edema surrounding the tendons of interest on both sagittal and axial planes. For good measure, you scan through the rest of the patient’s hand to look for any signs suggestive of a foreign body or adjacent tendon injury.

You’re not sure if it was the hypnotic fanning of the ultrasound transducer on the patient’s hand, or if the IV morphine kicked in, but your patient’s glassy eyes give the green light for your intern to start anesthetizing the wound for irrigation. As you supervise your intern with high-pressure irrigation, you wonder to yourself what the subspecialist services would say if they knew just how many non-emergent consults we save them from seeing in the ED. You subconsciously shrug your shoulders and silently thank your lucky stars that you chose the perfect profession…one that doesn’t prompt oral diarrhea of expletives every time your pager goes off at home.

Tips and Tricks: How to Evaluate Tendons Via Ultrasound

• A careful history and physical exam will usually reveal whether tendon injury or disruption has occurred. Remember that normal function can be seen on physical exam with 90% tendon disruption.

• Ultrasound can be used to augment clinical findings and help expedite the diagnosis.

• Complete tears are usually easy to diagnose. Partial or small tears can be assessed via bedside ultrasonography.

• Use the 7.5 to 10 MHz linear array transducer.

• Superficial structures (like flexor and extensor hand tendons) are difficult to visualize due to echo reverberations from the transducer. Even with high-frequency transducers, better visualization might be achieved with a standoff pad or liquid interface to provide a better acoustic window.     

• 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.

• 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.

• 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.

• If the ultrasound beam is not aimed directly parallel to the tendon fibers, a false hypoechogenicity artifact may be noted (anisotropy).