The most common causes of a Swan Neck deformity are a diagnosis of Rheumatoid Arthritis (RA), an untreated Mallet or “Baseball” finger, and congenital (born with) Swan Neck. Swan Neck deformity is a common problem in people with a connective tissue disease known as Ehlers-Danlos Syndrome (EDS).
Swan Neck deformity is common in RA as joint inflammation stretches the soft ligaments and capsules that keep the joints and tendons in proper alignment. When the tissue that normally keeps the finger from bending backwards is compromised, the PIP joint (the joint in the middle of the finger) stretches into hyperextension and the resulting imbalance causes the DIP (the joint closest to the finger tip) to bend down into flexion.
A Mallet Finger (loss of the ability to extend or straighten the DIP joint) if untreated, can result in imbalance of the tendons and ligaments that normally bend the PIP joint. The ligaments that normally lie on top of the finger are torn at their distal (end) attachment. Without this attachment, the ligaments apply more force across the PIP joint, pulling it into hyperextension.
Many people are born with loose or lax joints that is often misnamed “double jointed”. This laxity allows the fingers to bend backwards without there being any injury or indeed, without it being a problem. In severe cases, treatment with appropriate splints is called for. For persons with Ehlers-Danlos Syndrome, this hyperflexibility is progressive and can result in significant problems using the hands. Splinting for persons with EDS is an important aid to hand function.
A Swan Neck deformity is characterized by hyperextension (bending “backwards”) at the PIP joint (the middle knuckle) and flexion (bending down towards the palm) at the DIP joint (the end knuckle). In severe cases, the finger cannot be flexed at the PIP joint without passively (using the other hand) bending the finger to get it “started”.
Oval-8 Finger Splints from 3-Point Products are designed to keep the finger in proper alignment and prevent hyperextension at the PIP joint. Often when hyperextension at the PIP is controlled, the ability to control motion at the DIP joint is also improved.