Results of studies around surgical outcomes for Kienböck’s disease are not consistent. What works best? When should the affected wrist bone (the lunate) be surgically removed? Can surgeons use the amount of damage to the joint surfaces as a guide in making this decision?
Kienbock’s disease is a condition in which the lunate loses its blood supply and dies, causing pain and stiffness with wrist motion. In the late stages of the disease, the bone collapses, shifting the position of other bones in the wrist. This shifting eventually leads to degenerative changes and osteoarthritis in the joint.
The current study reports on the long-term results of proximal row carpectomy (PRC) for advanced Kienböck’s disease. By looking back at results, we may be able to identify when surgery is needed and for which patients.
The wrist is made of eight separate small bones, called the carpal bones. The lunate is one of these bones. There are two rows of carpal bones that connect the two bones of the forearm, the radius and the ulna, to the bones of the hand. Proximal row carpectomy refers to the surgical removal of wrist bones in the row closest to the forearm.
In late-stages of Kienbock’s disease, surgeons focus on treating the wrist osteoarthritis that results when the lunate collapses and dies. One surgical option at this stage is proximal-row carpectomy. Carpectomy means excision (removal) of one or more of the carpal bones.
When the lunate has collapsed, but the wrist joint is not terribly arthritic, the four carpal bones of the proximal row may simply be removed. This allows the distal row (the other four bones) to slide down a bit and begin moving against the forearm bones instead. Without the proximal row of bones, the wrist loses its ability to perform complex movements. It becomes more of a hinge joint like the knee.
The advantage is that there is still a good deal of wrist motion. That’s better than having a wrist fusion, which is another surgical option. Proximal row carpectomy is not the first line of treatment for this condition. It’s really considered a salvage procedure. That means it’s a way to save motion at the wrist. A proximal row carpectomy is a good solution when the patient needs a flexible wrist more than a strong one. It is used when there is advanced disease to try and avoid fusing the wrist and losing all motion.
There are some potential disadvantages to proximal row carpectomy. After the carpectomy, the main load on the wrist with grip and functional activities goes through the new capitate-radius joint. This is where the capitate bone of the wrist now joins the radial bone of the forearm.
In this study, 21 patients with stage III or IV (advanced) Kienböck’s disease were followed for an average of 10 years. The range was from four to 17 years. They all had a proximal row carpectomy for advanced Kienböck’s disease. The condition was diagnosed by clinical exam and X-rays.
Outcomes were measured by pain, motion, grip strength, and function. Disability was assessed using two tools: the Quick Disabilities of the Arm, Shoulder, and Hand (Q-DASH) and the Patient-Related Wrist Evaluation (PRWE). These self-reported surveys are both reliable and valid to measure results mentioned. Patient satisfaction was also measured on a scale from extremely satisfied to extremely dissatisfied.
X-rays were taken right after the carpectomy and at the final follow-up appointment. The main area of interest was the joint space between the capitate and the radius. Narrowing of the joint space is a possible negative outcome of the surgery.
Most of the patients (89 per cent) were either satisfied or extremely satisfied with the results. No one was dissatisfied. But half the group reported mild pain that could account for less than 100 per cent satisfaction.
Although the patients weren’t having any symptoms of it, degeneration of the radiocapitate joint was seen on X-rays in almost everyone. Joint narrowing ranged in degree from mild to severe. Most of the patients were able to return to their jobs without any problems. Only one manual laborer was unable to go back to his previous occupation.
Failure was defined as persistent pain requiring a wrist fusion. All failures occurred in patients for different reasons. In one case, cysts formed in the capitate and the patient had a full thickness defect in the joint cartilage. In another case, the bones of the wrist were jammed together causing weakness and instability.
This may be the longest study done looking at the long-term results of proximal row carpectomy for advanced Kienböck’s disease. The authors admit they still were unable to say when a carpectomy should be done. Using joint cartilage between the capitate and radius as a basis for decision didn’t pan out. And some of their results conflicted with the results of other studies suggesting the need for continued investigation of this problem.