You can find a more thorough discussion of swan neck deformity of the finger in our publication A Patient’s Guide to Swan Neck Deformity of the Finger. Swan neck deformity sounds elegant but as you have discovered, it can be very limiting.
To the rest of the world, it just looks like a crooked finger. The tip of the finger is bent at the distal interphalangeal (DIP) joint while the middle joint (proximal interphalangeal or PIP) is hyperextended. However, human anatomy is not simple and that description does not begin to tell you how complex a “crooked finger” can be.
In the proximal interphalangeal (PIP) joint, (that is the middle joint between the main knuckle and the tip of the finger), the strongest ligament is the volar plate. This ligament connects the proximal phalanx (bone closest to the palm) to the middle phalanx on the palm side of the joint. The ligament tightens as the joint is straightened and keeps the PIP joint from bending back too far (hyperextending). Swan neck deformity can occur when the volar plate loosens from disease or injury.
Rheumatoid arthritis (RA) is the most common disease affecting the PIP joint. Chronic inflammation of the PIP joint puts a stretch on the volar plate. As the volar plate becomes weakened and stretched, the PIP joint becomes loose and begins to easily bend back into hyperextension. The extensor tendon gets out of balance, which allows the tip of the finger to get pulled downward into flexion. As the tip of the finger bends down and the PIP joint hyperextends, the swan neck deformity occurs.
Gripping objects and picking things up becomes very difficult when this deformity is present. The main goal of treatment is to prevent the joint from becoming fixed or “stuck” in extension and no longer able to bend. Conservative care is tried first. A physical or occupational therapist addresses the imbalances that have formed the swan neck deformity. Stretching, massage, and joint mobilization are used to try and restore finger alignment and function.
A special splint may be used to keep the PIP joint lined up, protect the joint from hyperextending, and still allow the PIP joint to bend. This approach works best for mild cases of swan neck deformity in which the PIP joint is supple. Many hand surgeons recommend at least six weeks with the splint and exercise to improve PIP joint mobility before performing surgery.
There are several different ways to approch this problem surgically. Which one to choose is determined by the surgeon based on his or her experience and preference, and based on a number of different factors specific to the patient.
Some of the decisions about which method to use depend on how much joint stiffness is present in the proximal interphalangeal (PIP) joint. Earlier deformities may be more supple (not as stiff as the more advanced or severe cases) and have not been studied as much so evidence for outcomes remains limited. Joint replacement or fusion are additional possible surgical alternatives if repair or reconstruction fails.