Swan neck deformity (SND) affects your fingers. It occurs when multiple joints in your fingers bend in unusual positions because of a health condition or injury.

SND can cause pain, as well as limited use of your fingers and hands. Both nonsurgical and surgical options are available to help with symptom management and potentially correct your finger alignment. Keep reading to learn more.

Your fingers have a number of components. SND affects many of these parts, including your:

  • three finger bones (phalanges)
  • two interphalangeal joints, which are above your knuckle
  • tendons
  • ligaments

SND occurs when your two interphalangeal joints point in unnatural directions and cannot straighten into a flat position.

For example, the middle joint of your finger may hyperextend, or point upward. This joint is called the proximal interphalangeal (PIP) joint.

The end joint of your finger may also flex, or point downward. This joint is called the distal interphalangeal (DIP) joint.

You can only get SND in your fingers, not your thumb. Unusual bends in your thumb may be a condition called mallet finger. You may also end up with mallet finger if just the end joint of your finger droops.

SND can be caused by a variety of conditions, including:

Often, the finger joints malfunction when the volar plate, a main ligament in the finger, becomes too loose. This leads to the PIP joint pointing upward. It also affects tendons in your finger, causing the DIP joint to curve downward. This often occurs if you have certain chronic health conditions like RA.

RA can affect your volar plate because of the inflammation the condition causes throughout your body, especially in the lining of your joints. This creates abnormal tissues that can weaken your volar plate. Inflammation also alters the bones, cartilage, tendons, and other ligaments in your fingers.

You may develop SND because of other issues to the hand, such as injury. This may cause joint damage or tightened muscles, leading to your fingers bending in the SND position.

You should see your doctor if you notice a change in the bending of your finger joints. It’s possible that your doctor may be able to diagnose the condition just by looking at your hands during a physical exam.

Your doctor may confirm the diagnosis after an X-ray. This procedure also allows your doctor to view the bones and joints in your fingers for abnormalities or injury.

The treatment for SND can vary, depending on the condition’s severity. Noninvasive treatments include physical therapy (PT), occupational therapy (OT), and splints. More invasive procedures include surgery. These can range from minor soft tissue repair to more drastic measures like replacing or fusing the finger joint.

Your doctor will aim to correct SND and restore function to your fingers using the best method for your specific case.

Physical therapy and occupational therapy

If SND is mild, your doctor may recommend PT or OT as your first line of treatment. PT or OT involves exercises, stretches, and massage to help your fingers and hands build up balance and regain strength and mobility.

As a first-line treatment, your therapist may target the PIP joint. This may result in correcting your DIP joint at the same time.

PT and OT are also a crucial component of recovering from finger surgery.

Splinting

Your doctor may advise a splint to try to correct and stabilize the SND. This may be done in tandem with PT or OT.

Splints may include your entire finger or your joint specifically, such as with a ring splint. This is a figure-eight splint that you wear around the PIP joint all the time for several weeks. You can still bend your joint downward with this type of splint.

Other splints may be worn around the clock, or possibly only during certain parts of the day. Splints may restrict all movement of the finger or allow for some use of it.

Soft tissue repair

Soft tissue repair is a type of surgery that focuses on the skin, tendons, and ligaments (soft tissues) near the middle joint of the finger. It’s a type of surgery your doctor may recommend for moderate-level SND, as the surgery may not help more serious cases.

One type of soft tissue repair is the superficialis sling. This targets the volar plate to help it better restrain the middle joint of the finger from hyperextension while allowing for downward movement in the joint.

PIP joint arthroplasty

Correcting SND may require the replacement of a joint in your finger. PIP joint arthroplasty is when your doctor replaces the middle joint in your finger.

Your doctor may recommend this type of surgery if your middle joint is stiff. Your doctor will also balance the soft tissues surrounding your new joint to restore movement in the finger.

You’ll find after a joint arthroplasty that it’s much easier to move your fingers, and you may experience less pain. Keep in mind that joint replacements may wear down over time.

Finger joint fusion

Finger joint fusion is when your doctor fuses the joint in your finger so it can no longer move. It’s most commonly done in the DIP joint. Your doctor will recommend this if this joint isn’t working properly. After the surgery, you will be unable to move the joint and it will stay straight.

Your doctor may recommend a joint fusion in your PIP joint instead. This procedure results in your doctor fusing the joint in a bent position.

This surgery should reduce pain in the affected finger joint.

Recovery from surgery on your finger will take many weeks, if not months. Your doctor will give you a postoperative plan for daily care of the surgically repaired finger. They’ll likely recommend that you wear a splint while your finger heals.

You’ll need to see your doctor a few weeks after your surgery and possibly another time or two thereafter. It’s also likely that you’ll attend weekly PT or OT sessions to reduce swelling and pain and gain strength and mobility in the digit.

See your doctor if you notice symptoms of SND in your fingers. This may be the result of a serious underlying health condition or because of an injury to your fingers or hand. SND may be treated with less invasive measures if it’s diagnosed before the finger joints become very stiff in the hyperextended and flexed positions.