NAILBED & FINGER TIP INJURY
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What is a Nail bed Injury and how is it treated?
Lets look at the type of injuries that your finger nail and finger tip can sustain after a traumatic injury, as such can occur after being crushed by a door for example. If you have worsening pain in your finger tip without any memorable trauma, it cause may be an infection around the nail, which is discussed separately (see talk).
The mildest injury to the finger tip is a collection of blood under the finger nail, called a "subungual hematoma".
The nail is stronger than the skin below it, called the nail bed, also known as the "sterile matrix". If the finger gets crushed, the nail may be ok but but the nail bed will tear, causing bleeding under the nail. This may be problematic because there is a limited space under the nail and as it fills with blood, the pressure will increase to cause a throbbing pain.
The treatment is "trephination", which is puncturing the nail to allow the blood to evacuate, and thus decrease the pressure under the fingernail. This needs to be done under sterile conditions to prevent an infection by introducing bacteria into this sterile area. If blood under the nail forms, but doesnt cause pain, then no treatment is required because "trephination" only helps to reduce pain, it doesn't help the finger heal faster. If the blood is left alone, it will be reabsorbed slowly by the body (like a bruise that goes away over time).
Sometimes the force of whacking your finger is strong enough to pull the nail off the finger, as well as tear the underlying skin (the sterile matrix). In these cases, the skin must be repaired using very thin stitches (which are slowly absorbed by your body). The nail that came off is cleaned, then a hole is placed in its center (to allow any blood to pool out), and the nail is placed back into position. The fingernail is dead once its pulled off, so placing it back onto the finger isn’t going to save it. However, by placing the old nail back onto the finger, under the base of the nail where it grows out from, called the eponychial fold, and splints this open, thus preventing a scar from forming that could block a new nail from growing. The skin under the nail will heal and allow the new nail to grow over it. A new nail typically takes about 1-3 months to grow back.
If this underlying skin (sterile matrix) is not repaired, it may form a scar that prevents the new nail from growing over it, or that causes the new nail to be wavy (almost like paving a road over uneven ground).
What is a Broken Finger Tip ("Tufts Fracture") and How is it treated?
Sometimes the force of injury to the finger tip is so strong that it injures the fingernail, the skin underneath, and the bone at your finger tip, called the "distal phalanx". A nail injury in combination with a finger tip fracture is called a “Tufts fracture”.
Typically, these injuries are treated the same as a nail injury, where the nail bed is repaired with stitches, the old fingernail is returned to its position to allow a new nail to grow without being blocked by scar tissue. When the old nail is put back into position it acts as a natural splint to protect the broken bone by holding it in place. The finger is also protected with an alumafoam splint for 2 weeks. After 2 weeks, the bone is sufficiently stable to begin activities. Sometimes the fracture does not fill in completely with bone and scar tissue actually forms between the bone fragments. This is called a "fibrous union", meaning the bone unites with scar tissue instead of bone. When this occurs in certain bones like the leg or arm bone…it can be painful and requires surgical treatment, however its been shown in many reports that patients who develop fibrous healing of the finger tip do great, and almost never complain of pain.
What is the long term outcome?
There can be complications with the healing of a nail bed injury, mostly related to fingernail appearance.
If the nail bed (aka the sterile matrix) is torn, scarring can occur, even if stitches are used to repair it (which is the best way to minimize scar tissue formation). Too much scar tissue can cause the nail to look abnormal. You may see various deformities like notching, ridges in the nail, elevation of the nail (its like paving over uneven ground). The most concerning complication is the formation of scar tissue where the finger nail originates. If the nail fold (eponychium) becomes scarred down the nail will either fail to grow, or if theres only some scar tissue, the nail will grow with a split down the middle. These complications can often be treated with further surgery to remove the scar tissue and improve the chance that normal nail grows.
If you are having pain at the tip of your finger, without any history of traumatic injury, there may be an infection developing. Infections around the finger nail or finger tip pulp can be very painful (for more, see this talk).
You can watch a nail bed heal on time-lapse video (really cool youtube video)...
Related articles: broken finger, broken hand, jersey finger (finger tendon injury), mallet finger (finger tendon injury)
Reference
1) Lee DH et al. Fingertip injuries: an update on management. JAAOS 2013; 21: 756-66. full article. review.
2) Simon RR, Wolgin M. Subungual hematoma: association with occult laceration requiring repair. Am J Emerg Med 1987; 5: 302-4. full article. nailbed lacerations re repair occur in 60% of cases with subungual hematoma >50% nail, and 95% of tufts fx.
3) Seaberg DC et al. Treatment of subungual hematomas with nail trephination: a prospective study. Am J Emerg Med 1991; 9: 209-10. full article. equal outcome for trephanation alone vs. trephanation + lac repair.
4) Strauss EJ et al. A prospective, randomized, controlled trial of 2-octylcyanoacrylate versus suture repair for nail bed injuries. J Hand Surg Am 2008; 33: 250-53. full article. no difference between dermabond and 6.0 chromic gut for repair of nailbed lac.
5) O'Shaughnessy M et al. Nail re-growth in fingertip injuries. Ir Med J 1990; 83: 136-7. full article. splinting epinycheal fold open has no effect on re-growth of nail, 50 pt without splint had no difference to control group, severity of initial injury has greatest impact.
6) Ashbell TS et al. The deformed finger nail, a frequent result of failure to repair nail bed injuries. J Trauma 1967; 7: 177-90. full article. without repairing nailbed, high risk nail deformity.
7) Da Cruz DJ et al. Fractures of the distal phalanges. J Hand Surg Br 1988; 13: 350-52. full article. outcomes not as good as believed. by 6 mo, <50% union, only 17% fully recovered.
8) Chim H et al. Open reduction and interfragmentary screw fixation for symptomatic nonunion of distal phyalangeal fractures. J Hand Surg Eu 2008; 33: 71-6. full article. 13/14 req. ROH b/c painful. but did effectively unite fx, best via nailbed approach.
9) Ito H et al. Fingertip amputation salvage on arterial anastomosis alone: an investigation of its limitations. Ann Plast Surg 2010; 65: 302-5. full article. challenge of replant the tip, venous anastomosis limits success of more distal replants.
10) van den Berg WB et al. Comparison of three types of treatment modalities on the outcome of fingertip injuries. J Trauma Acute Car Surg 2012; 72: 1681-7. full article. compare reconstruction, bone-shortening, or conservative treatment in 50 patients, no difference in sensation, strength, or cosmesis. high rate overall for nail deformity and cold intolerance.
11) Lee LP et al. A simple and efficient treatment for fingertip injuries. J Hand Surg Br 1995; 20: 63-71. full article. good outcome heal by secondary intention. best return sensation, but high risk hook nail if no soft tissue volar.