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What is a Jersey Finger?
A Jersey Finger is a tendon injury at the tip of your finger.
Its a tear to the tendon that bends your finger (specifically called the flexor digitorum profundus). The tendon can be either torn or it can be pulled off the bone (where it attaches).
A Jersey Finger specifically refers to a tendon injury at the tip of your finger (also called a Zone 1 Flexor tendon injury)
This injury got the name Jersey Finger because rugby players would get their fingers caught in an opponents jersey while trying to tackle them and the pull of the jersey on the finger would cause this injury. 75% of these injuries occur in the ring finger because when the fingers are bent, the ring finger is slightly longer than the others and therefore it is more exposed.
Its the opposite of a Mallet finger, which is a tear of the extensor tendon, see talk, which straightens the finger.
Remember that tendons attach muscle to bone. The tendon gets pulled off where it attaches to the finger bone. The injury occurs when the finger tip is pulled backward before the tendon can stretch to accommodate the pull (tendons are like rubber bands: they can stretch when pulled slowly, but if pulled to quick they will snap).
How is a Jersey Finger diagnosed?
This injury is diagnosed by examining the finger.
When you ask someone to make a fist, the injured finger will remain sticking up, because the flexor tendon is torn.
Our fingers are kept straight by the balance between two tendons: the flexor tendon (which bends the finger) and the extensor tendon (which straightens the finger). Its like a jockey that uses reins to make the horse go straight. So if one of these tendons break, the finger will be off balance, and will bend away from the injured tendon.
X-rays of the hand are always performed to rule out other injuries, and also, like the mallet finger, there are occasionally avulsion type fractures to the finger tip instead of a true tendon tear. An avulsion type fracture is when the tendon pulls off a piece of bone instead of actually tearing (like pulling a flower out by its roots). The effect is the same. The tendon is flapping in the wind.
How is a Jersey Finger treated?
There are different levels of severity in a Jersey Finger based on how far the tendon retracts once it gets torn. Overtime the tendon shortens more and more, it will slowly curl up into the wrist or forearm. Unfortunately, the best way to restore the tendon length is to reattach the ends via surgery.
The basic classification system is called the Leddy Parker Classification, and it has 3 types.
Type 1 is the worst, the tendon retracts all the way to the palm and it needs to be treated with surgery within a week because when the tendon moves so far out of position, its nutritional supply is disrupted (nutrition to keep the tendon healthy usually comes from the vincula and flexor sheath).
A Type 2 injury occurs when the tendon retracts to the PIP (the middle finger joint) and this still needs to be fixed, but it can wait a few weeks because the tendon is still getting nutrition. Doctors arent worried that it will shrivel up and die. It still needs to be treated in a few weeks before excessive scar tissue forms around the tendon and prevents it from being stretch back out to its normal length.
A Type 3 injury is the avulsion type fracture, which should also be repaired, but the piece of bone acts like an anchor and prevents the tendon from drifting. The tendon hardly retracts at all.
Surgery consists of pulling the tendon back to its normal length, and then tying the ends back together.
What is the long term outcome?
The outcome is generally very good but there can be some persistent finger stiffness.