Swan Neck Deformity
What is Swam Neck Deformity?
Basic knowledge of finger anatomy is useful to understand the complexity of Swam Neck Deformity. Each finger (except the thumb) is composed of three bones called phalanges. The joints between the phalanges are known as interphalangeal joints (IP joints). The joint at the fingertip is the distal IP joint (DIP joint) and the proximal IP joint (PIP joint) is the middle knuckle. Ligaments anchor bone to bone supporting the joints, while tendons connect the bones to muscle allowing movement. Extensor tendons on the back of the hand allow the IP joints to straighten and flexor tendons allow the fingers to bend into a closed fist.
When the fingers are straightened, the strongest ligament on the palm side of the PIP, known as the volar plate, tightens to prevent over extension of the joint. A lax volar plate results in hyperextension at the PIP, causing imbalance in the extensor tendons and allowing the flexor tendons to pull the DIP downward. Swan Neck deformity is characterized by hyperextension of the PIP accompanied by flexion of the DIP. This malformation is so named because this configuration resembles a swan’s neck.
What causes Swam Neck Deformity?
Any condition that results in laxity of the volar plate can cause Swan Neck Deformity. Rheumatoid Arthritis (RA) is the most common culprit. The overstretched volar plate occurs due to chronic inflammation of the PIP joint. Trauma, stroke, and various nerve disorders such as Parkinson’s and cerebral palsy can all affect the small muscles in the hand, weakening the volar plate, eventually leading to Swan Neck Deformity. Additionally, an untreated Mallet Finger can also result in Swan Neck Deformity.
What are the symptoms of Swam Neck Deformity?
If associated with trauma or RA there may be swelling, inflammation, or pain at the affected joints. Prior to the deformity becoming apparent there may be increasing difficulty flexing the fingers into a fist. Otherwise, the characteristic shape, in which the PIP is hyperextended while the DIP is flexed, is the most notable symptom. In severe cases, the affected finger cannot be flexed without assistance.
How is Swam Neck Deformity diagnosed?
A diagnosis of Swan Neck Deformity is usually evident upon physical examination. However, the physician will still require a complete medical history and review of symptoms to determine the underlying cause. X-rays may be ordered to visualize the joint surfaces and exclude fracture.
How is Swam Neck Deformity treated?
Conservative management aims to treat the underlying cause of the deformity, restoring balance to the joints. Specialized splints may be used to prevent hyperextension of the PIP which should resolve the flexion of the DIP. Rigorous hand therapy, consisting of daily exercise, massages and stretching, is crucial to restore and maintain flexibility of the joints.
When conservative measures fail, surgery is indicated. Several factors are considered in determining the type of procedure that is performed. In milder cases, the surgeon will realign, release and repair the soft tissues (skin, tendons, and ligaments) surrounding the PIP joint. Post-operatively this option requires extensive hand therapy to restore proper function.
The second option is a PIP joint arthroplasty. In this procedure the surgeon replaces the existing PIP joint with a new implant. Then the surrounding tissues are balanced to ensure proper mobility and flexibility of the new joint.
The final and most drastic option is joint fusion. Joint fusion binds the articulating surfaces and results in a joint that can no longer bend. Fusion can be done at the DIP, PIP or both. This procedure stabilizes the joint(s) and reduces pain and inflammation.
How can Dr. Knight help you with a Swan Neck deformity?
Whether as a result of trauma or Rheumatoid arthritis, Swan Neck deformity of the fingers can be a debilitating and painful condition. Over his many years of practice, Dr. Knight has acquired an extensive knowledge of these finger-specific ailments and he understands how important it is to reduce their effects, so as to allow you to return to your life, and your work.
HandAndWristInstitute.com does not offer medical advice. The information presented here is offered for informational purposes only. Read Disclaimer