Swan Neck Deformity: Causes, Diagnosis and Treatment
Swan neck deformity is a condition in which the distal joint (behind the nail) of the finger goes into flexion and the proximal joint goes into extension.
Before reading further it would be good to first see Finger Anatomy (skip if you have already done so).
Normally you can flex all your finger joints or extend them together. It is impossible to flex one joint and extend the other joint of the same finger. (yeah! I know some normal people can. But for most of us it's not possible) Why don't you try it right now.
So if one joint is flexed and the other is extended then it means that there is something wrong.
Now what is wrong?
Look now, there is only one tendon that is responsible for extending the both the joints of the finger. This is in contrast to the flexor tendons that are two in number. This extensor tendon divides into three slips (branches). The central one extends the proximal joint and the remaining two (one on each side of the finger) join further up and extend the distal joint.
Now if the lateral slips that extend the distal joint stop functioning for whatever reason, then the distal joint will remain flexed. The central slip continues to function (in fact it over functions because you still continue trying to extend the distal joint with your non functioning lateral slips) and this results in excessive extension of the proximal joint. This eventually produces swan neck deformity.
Causes of this deformity include
- rheumatoid arthritis (most common)
- mallet finger (due to rupture of lateral slips at their junction with bone)
- cerebral palsy (due to muscle imbalance)
- congenital joint laxity
Classification by Millender, Feldon and Nalebuff. It is divided into four types
- Type 1 and 2 are flexible deformities
- Type 3 and 4 are stiff deformities
- Type 4 has joint destruction, which is absent in type 3
Treatment includes the following
- Mild and flexible deformities can be treated by using a finger brace.
- Severe deformities may require the following surgical procedures
- skin release
- ligament reconstruction
- joint fusion
- joint replacement
Drug treatment to control rheumatoid arthritis. Physiotherapy of the hand is a must in order for any treatment method to be effective.
Frequently Asked Questions
How can I prevent this deformity?
Swan neck deformity can be prevented by controlling your rheumatoid arthritis. With the development of newer and better drugs for the treatment of rheumatoid arthritis lesser number of patients are having severe deformities.
Apart from this you should avoid injuring your hands and exercise them regularly.
Passively move each joint of your hand through it's full range of motion this will prevent them from becoming stiff.
If you notice the deformity early on, then use a finger brace to keep your distal joint in extension.
Don't wait and watch. Contact your doctor quickly before your deformity becomes fixed. Once the deformity is fixed then the results of any treatment are less predictable.
I hope the information provided was helpful. If you have any query you can ask me at the contact me page.
This page was last updated on 13th March 2009.
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