What's up, Doc? Stress caused by long ulnar bone leads to ulnar impaction syndrome
Q: I developed wrist pain, and the orthopedist said it was because one of my forearm bones was too long. Please explain what this is.
A: The hand, with more bones in it than any other part of our body, is a very important part of our anatomy and a key aspect of our evolution (for example, by enabling our use of tools). Multiple colloquialisms evidence this importance, for example “lend me a hand,” “she is handy with home repairs,” etc.
The balance of the transmission of forces from the forearm bones (the radius on the thumb side and the ulna on the pinky side) to the hand bones (the carpal bones) is closely modulated within the wrist (a pretty complex joint that allows a very large range of motion of the hand). For example, the ulnocarpal joint (the articulation between the ulnar bone and the carpal bones where force is transmitted across the triangular fibrocartilage complex, the TFCC) helps stabilize the wrist, having about 20% of the total forces transmitted through it when the wrist is in the neutral position, increasing to 40% to 65% of the transmitted forces under certain scenarios.
Some people’s ulnar bone is slightly longer than "normal," whether because they were born with a slightly longer ulnar or they developed a shortening of the radius (for example, after a wrist fracture or other injury). This can shift the balance of forces transmitted across the wrist, potentially causing excess stress on some of the structures within it. This condition is called the ulnar impaction syndrome (UIS).
Symptoms of UIS may develop over years as "wear and tear" on some of the structures in the wrist (for example, the TFCC) may cause some degeneration/inflammation, possibly leading to "bone on bone" movement within the joint as the "cushioning" effect of the soft tissues between the bones, including the TFCC, is compromised. This is more common in people who participate in sports that require repetitive and forceful use of the hands, such as rowing, tennis, gymnastics, rock climbing and many others.
The symptoms of UIS include pain and/or tenderness of the wrist, particularly on the pinky side, which worsens with heavy activity/grasping. In some cases there may be a perceived "clicking" sound, and even (less commonly) swelling.
The diagnosis of UIS is suspected based on the history and physical exam (for example, pinky-side wrist pain reproduced by certain motions), and may be verified by imaging (such as an X-ray or MRI). Because there are many possible causes of wrist pain (which occurs in up to 10% of all athletic injuries), seeing a specialist (for example, an orthopedist who specializes in the hand) is often appropriate.
As with many orthopedic issues, the initial treatment of UIS is usually conservative treatments of activity modification/rest and immobilization (in this case with a wrist splint). Anti-inflammatory medications (such as ibuprofen) are typically recommended to treat the pain, and physical/occupational therapy (including techniques to help minimize the stress on that part of the wrist when the patient resumes their normal activities) is also often part of the treatment plan.
In cases where conservative treatment is not adequate, surgery may be considered. There are several possible surgical approaches:
An ulnar shortening osteotomy (USO) procedure is done by an open procedure (an incision is made and the bones directly accessed) where a small part of the ulnar bone is cut out and the "gap" created then stabilized with metal hardware (including plates and screws which are often removed years later after the bone is completely healed). The initial recovery time is usually a couple of months, followed by physical therapy and strengthening exercises. About 90% of patients have good to excellent results following this surgery.
An arthroscopic "wafer" procedure where a small incision is made and a debridement procedure is done. This procedure uses a tiny camera on the end of a specialized and maneuverable tube inserted into the body for visualization, and small instruments inserted through a small incision to perform the procedure. Recovery time is usually shorter than with the USO procedure, and data has shown success rates about the same as with the more invasive procedure. However, not every patient’s condition has characteristics that make this approach a viable option.
Other possible procedures, even including treatment with a low-intensity pulsed ultrasound (although the data I found on this approach is very limited), may be an option for some patients.
People with wrist pain should see their health care provider, and if the diagnosis is uncertain they should see a specialist for further evaluation.
Jeff Hersh, Ph.D., M.D., can be reached at DrHersh@juno.com.
This article originally appeared on MetroWest Daily News: Dr. Jeff Hersh addresses ulnar impaction syndrome
