The function of the fingertip
The fingertip is basically a part of the body specialising in providing sensory feedback to the brain. The sensory input from the hand is so important that a disproportionately large part of the brain is devoted to interpreting the signals sent from the fingertips.
The fingertip provides length to the hand, and its second function is to aid grasp and provide stable fine manipulation of objects.
This image shows the area of the cortex of the brain and the part of the body it controls – you can see that the face and the hand are disproportionately represented, because of the amount of information transmitted to the brain from these parts of the body.
What is the fingertip made up of?
There are 3 components to the fingertip. Understanding the anatomy of these 3 components will help with understanding why these injuries cause so many problems!
The NAIL PLATE is the rigid part of the nail which grows from the germinal matrix and starts under the nail fold. The nail is designed to help protect the fingertip from trauma.
The DISTAL PHALANX is the name given to the underlying bone of the fingertip. The bone provides stability for the SPECIALIST FAT PAD or PULP of the fingertip, where the nerve endings are most abundant.
How is the fingertip injured?
There are a vast number of mechanisms of fingertip injury, ranging from a paper cut to an amputation of the fingertip. Virtually everyone will experience some sort of fingertip injury in the course of everyday life, but there are a few mechanisms which are worth mentioning individually:
– Crush Injuries These are commonly seen when the fingertip is trapped in a door – usually in the hinge side of the door, and are most common in young children. Again these range from fairly mild injury which recovers rapidly, to partial or complete amputations of the fingertip.
– Circular Saw Injuries These are unique injuries where the width of the saw blade can destroy up to several mm of tissue, and the nerves and vessels of the fingertip can be caught up in the saw mechanism producing significant nerve damage or destroying the blood supply to the fingertip. In addition, circular saws tend to push foreign material deep into the base of the wound, creating a high infection risk.
– Knife Injuries We often see sharp kitchen knives taking off the very tip of the finger. This is usually a clean wound without much crush component, but tends to bleed profusely.
Treatment of Fingertip Injuries
Fingertip injuries can be classified as either OPEN, when there is an associated wound or CLOSED, where there is no wound. In addition, each component of the fingertip (NAIL / BONE / PULP) can be described as STABLE or UNSTABLE.
The principles of treatment, therefore, are to firstly washout any open wounds and repair these if appropriate, and secondly to convert unstable injuries into stable injuries.
In practice, the majority of fingertip injuries are closed and stable. These injuries do not require input from a surgeon, and generally heal well.
Where the injury is OPEN, then the priority is to wash out the wound, remove any contaminated tissue, and repair it if possible. This can be done either in the Emergency Department or in the Operating Theatre, under a local anaesthetic.
Occasionally, the fingertip has been so badly damaged that the tissue is no longer viable. In this type of injury, the usual treatment recommendation is TERMINALISATION or amputation of the fingertip.
Generally speaking, loss of tissue in the pattern of the green lines on the left can be managed conservatively, whereas loss of tissue in the pattern of blue lines on the right will usually require surgery
How long does it take for a fingertip injury to heal?
It usually takes around 3 months to recover from a fingertip injury, but around 2 years or more to forget about the injury.
Common problems associated with fingertip injuries include:
– Cold Intolerance is the name given to the symptom of pain in the fingertip in a cold environment, and this can be a real problem for people who work out-doors or during winter months. Although cold intolerance generally improves with time, it can take many years to settle.
– Hypersensitivity is very common, and can be considered a normal part of recovering from a fingertip injury. This hypersensitivity can make the finger difficult to use, and people tend to hold the finger away from the rest of the hand in order to avoid contact. This creates a vicious circle, where lack of use perpetuates the hypersensitivity. Paradoxically, the advice given is to desensitise the fingertip using massage and gently tapping it against a tabletop.
– Stiffness of the distal interphalangeal joint is common, and we usually recommend early movement of this joint to avoid it becoming stiff. This can take considerable will-power, because the finger is usually quite sore to move early on.
– Abnormal Nail Growth can occur where there has been damage to the nail-bed or the finger has been terminalised. This can make caring for the nails troublesome and occasionally secondary surgery is needed to remove parts of the nail to avoid skin irritation.
© Fife Hand Service 2021