Scalp lacerations over hair-bearing areas have traditionally been closed with staples. An alternative technique is the Hair Apposition Technique, also known as the HAT trick. This technique provides a more cost-effective, faster, and less painful approach to scalp laceration repair. This is not a new thing. It’s been discussed in the literature since 2002, but it astounds me how many experienced practitioners have not adopted this simple and time-saving technique.
How does the HAT trick work? Imagine the scalp hairs as suture ties already embedded in the skin. After wound irrigation and a meticulous examination, twist together 3-7 strands of hair on one side of the wound. Do the same on the other side of the wound. Interlock these two hair bundles in a 360-degree revolution. No need to tie a knot. Secure the intertwined hair bundles by applying a few drops of a tissue adhesive. Not only can you often get away with doing this technique without injection of an analgesic, the patient no longer needs to return for staple removal in 7-10 days. The hair will unravel on its own after a week. So, you also save them a return visit.
What people don’t often realize is that hair apposition isn’t just for tiny scalp lacs. It’s an evidence based technique, and has been studied for safe use in lacerations as long as 10 cm. You can repeat as needed to close the length of the laceration.
It’s also important to recognize that hair apposition is not just for the rapunzels out there with long, glorious flowing locks. It works great in short haired people too. The only real modification you have to make is to get a pair of kelly clamps, lock up the hair on both ends, twist, and glue.
References for this technique:
- Hock MO, Ooi SB, Saw SM, et al. A randomized controlled trial comparing the hair apposition technique with tissue glue to standard suturing in scalp lacertions (HAT study). Ann Emerg Med. 2002;40(1):19–26.
- Ong ME, Coyle D, Lim SH, et al. Cost-effectiveness of hair apposition technique compared with standard suturing in scalp lacerations. Ann Emerg Med. 2005;46(3):237–242.
This is a question regarding a picture on your wound preparation area of the site…saw you are wearing some eyewear in this picture. Do these offer magnification or just protection? I know there are some expensive options out there (Loupe style eyewear) ; however, I really dont want to spend the money for these. Any products out there that you would recommend to get a degree of magnification with a focal point where we would want it for wound repair (12-36inches)? Thanks
Hi Adam,
Thanks for checking out the site. No, there is nothing special about that eyewear, except that it has some side splash protection and an attachment so it can hang around my neck! no magnification. Some of the docs I work with have purchased loupes (quite an investment as you said) but I think this is only really necessary for fine detail work (e.g. working with 7-0 suture and smaller), which is a little beyond the scope of what I do.
Why might you choose this technique over simply glueing the wound?
If the wound is tension free, you can simply glue it. Hair apposition is a useful technique when there are tension forces splaying the wound edges apart.
Thanks for the reply.
I’m now undertaking a critical appraisal of the studies for HAT over suturing, very interesting topic that I’m sure will promote a change in preference of technique.
if gluing the scalp what advice must be given post procedure re washing blood stained hair over the next few days. will the glue hold for a gentle wash?
Thanks for a great question. Any prolonged exposure to water, gels, ointments, or liquids will potentially compromise the integrity of the glue. It will probably hold up OK versus brief water exposure, however the other issue is the mechanical compromise from scrubbing and tampering with the hair. I generally advise patients to leave it alone as much as possible, and if they feel compelled to clean (if the hair is bloody–though where I work we try to take care of this beforehand) to use a moist washcloth gently around the surrounding area Only.
Wanted to add some practical HAT tricks. First, it requires two people to do it properly, one to hold the hair strands and a second to apply the drop of adhesive. We use Dermabond Advanced pen in our shop and found that the glue dries and blocks the applicator outlet just as quickly as it dries on the patient and so we found that continuously squeezing small amounts of the adhesive out of the tube while we wait for the first tangle to set allows us to use the same tube for subsequent hair tangles without opening additional ones.
Thanks again for all the great posts. Also enjoyed your recent review of extensor tendon injury on EM:RAP.
Thanks for the great post! What post wound care instructions to you give the families? When can they wash hair etc?
Dermabond and other medical grade cyanoacrylate glues are pretty resilient, but I still advise patients/parents to refrain from washing/shampooing the hair for about 5-7 days, with the expectation that the glue will start coming off naturally by this time (and if it doesn’t, a little water and shampoo by this point will appropriately speed the process). But at the same time, if the area accidentally gets a little wet prematurely, no need to panic. No swimming pools, hot tubs, ocean water, etc. Thanks for reading!