In this article, Dr. R. J. Strauch from the Department of Orthopedic Surgery at Columbia University Medical Center in New York City presents an update on the treatment of two causes of wrist arthritis. Both types involve the scaphoid (wrist) bone. The scaphoid is a key player in wrist arthritis because of its location. It sits in the center of the wrist.
Any trauma, injury, or other disease process that affects the scaphoid can also potentially affect the other bones and ligaments in contact with the scaphoid. Damage (tears or ruptures) of the scapholunate ligament (between the scaphoid and lunate bones) puts the wrist at risk for uneven wear, joint degeneration, and wrist arthritis. Fractures of the scaphoid bone that don’t heal (called a nonunion fracture) can result in the same process of joint destruction and arthritis.
Dr. Strauch focuses his attention on the treatment of two specific scaphoid conditions that can lead to wrist arthritis. The first problem is called scapholunate advanced collapse (SLAC).
As the name suggests, both the scaphoid and the lunate wrist bone shift out of alignment. The wrist becomes painful, tender, and unstable. Wrist motion and quality of movement become abnormal. Abnormal wear and tear lead to joint destruction and arthritis as described.
The main cause of scapholunate advanced collapse (SLAC) is trauma resulting in a tear of the scapho-lunate ligament. Crystals from pseudogout that form inside the joint can also create a SLAC condition.
The second problem is called scaphoid nonunion advanced collapse (SNAC) arthritis. A fracture of the scaphoid bone that doesn’t heal creates a joint that is unstable. Trauma is the main cause of this type of scaphoid collapse.
Treatment for these two wrist problems is similar with a few key differences. Conservative (nonoperative) care can be tried first for either condition. A hand therapist (occupational or physical therapist) can fit the patient with a special splint. The splint is meant to hold and protect the joint giving it time to heal.
Pain is managed with pain relievers and heat, cold, or electrical stimulation. The surgeon may try steroid injections to reduce pain and inflammation. Steroid injection is limited by the fact that this medication can cause breakdown of the soft tissues and joint.
Surgery can be done to fuse the joint, remove the affected bones, or denervate (destroy) the sensory nerve sending pain messages to the brain. Wrist fusion or arthrodesis can be done in one of several ways. In one approach, the scaphoid bone is removed.
Then the four remaining bones around the scaphoid (lunate, hamate, capitate, triquetrum) are wired or held together with a round metal plate and screws. Bone graft may be used to help stimulate bone growth in the spaces between the bones. This wrist fusion procedure is called a four-corner arthrodesis.
Studies have shown the importance of clearing out any debris in the joint during the bone removal and fusion procedure. Using enough screws (at least two per bone) to hold the bones together is another key to a successful outcome. Using the right sized screws is equally important.
Over the years, surgeons have tried many different ways to fuse the wrist with varying results. The goal is to get a stable joint while maintaining as much motion as possible. Other methods being studied and compared to the four-corner arthrodesis include fusing just the capitate and lunate together and removing different bones (sometimes removing the scaphoid, sometimes the lunate or triquetrum) and seeing the results.
Results are measured and compared using joint range-of-motion, pain, tenderness, grip strength, and wrist function.
Some surgeons prefer to remove the row of wrist bones closest to the forearm. This procedure is called a proximal row carpectomy (PRC). The advantages to this treatment approach include quick return of wrist motion, no hardware, and of course, no limitations normally caused by a fusion. No hardware also means no complications such as screws breaking or backing out or the need for a second surgery to remove the hardware later after healing is complete.
Choosing between a proximal row carpectomy (PRC) versus four-corner arthrodesis is done on a case-by-case basis. PRC has several advantages over the four-corner fusion. There are fewer complications and better overall results with PRC.
The downside is a weaker grip strength and a greater chance of developing arthritis later. If strength is important for daily activities or work tasks, then the four-corner arthrodesis is the preferred treatment choice.
In summary, wrist arthritis from scaphoid bone or scapholunate ligament injuries can be treated in a step-wise fashion. The least invasive (nonoperative) method can be tried first. (splint, hand therapy). If the patient fails to improve or has only limited change in pain, then injection therapy or nerve denervaton can be tried.
Surgery is the last option when pain and weakness and loss of function persist or progress. Surgery can also be done in stages. Removal of the damaged scaphoid and a four corner-fusion allow for some wrist motion to be saved. Alternately, the affected row of carpal (wrist) bones can be removed completely.
Further treatment failure may lead to total fusion of the wrist joint. Future studies comparing the results of each treatment method based on patient age, strength, activity level, and work requirements may help guide treatment decisions for these two problems (scaphoid lunate advanced collapse and scaphoid nonunion advanced collapse).