The Use of Logic and Common Sense in Treating Thumb Arthritis
Medicine is moving more and more toward evidence-based practice, but research hasn't caught up in all areas. There are still times when good old common sense and a little logic go a long way. One hand surgeon from Ohio State University Hand and Upper Extremity Center use this case report to demonstrate this point.

The patient was a 58-year-old woman with long-standing pain at the base of her thumb (where the thumb meets the wrist). She also had hyperextension (excessive backward motion) of the metacarpophalangeal (MCP) joint. The thumb MCP joint if the large knuckle you see when you tuck your thumb inside your palm.

X-rays showed considerable arthritis at the trapezial-metacarpal (TM) joint (thumb-to-wrist connection) but no arthritis at the metacarpophalangeal (MCP) joint (large knuckle joint). The dilemma in this case is how to treat the arthritic TM joint and the hyperextended MCP while preserving thumb motion and function. By the way, the diagnosis for these two problems was MCP joint hyperextension associated with TM arthrosis.

In making a treatment plan, the surgeon looked at the current evidence. He found very few studies to guide him. Most of the published papers were case series reporting the results of using one specific surgical technique. There were no studies comparing conservative (nonoperative) care with surgical treatment of MCP joint hyperextension. There were no studies comparing the different surgical techniques used for this problem.

He was able to see that most hand surgeons agree that when trapezial-metacarpal (TM) reconstruction surgery is done, the MCP hyperextension should be stabilized. The guideline is if there is more than 30-degrees of hyperextension of the MCP joint, then both problems should be surgically addressed at the same time.

If the MCP problem isn't addressed, then the force and load is transferred to the reconstructed TM joint and that can cause some problems. Stabilization procedures for the MCP include using pins to hold the joint while the TM reconstruction heals, release of the muscle (extensor pollicis brevis) affecting the MCP, fusion of the joint, and capsular release of the palmar side of the joint.

The limited evidence available showed the surgeon that temporary pinning of the MCP joint when there was less than a 30-degree hyperextension deformity did no good. Performing a tenotomy (tendon release and reattaching the tendon end to a different area of bone) has some benefit for most patients. Fusion of the joint doesn't always work. Recurrence of the excess motion is possible.

Releasing the joint capsule on the palmar side of the thumb seems to have the best results. This procedure is called a volar capsulodesis. In three separate small case series of 10 to 13 patients, there were excellent results with no recurrence the majority of the patients. Excellent results mean pain was reduced and the patients had good pinch grip function.

Armed with the information from these studies, this surgeon used logic and common sense to form his treatment plan. Preserving thumb motion was the number one priority. Treating the MCP hyperextension was deemed important to prevent risk of TM reconstructive failure. The volar capsulodesis was done to reduce MCP deformity and improve MCP joint alignment.

The patient was told ahead of time all of the surgeon's concerns, the pros and cons of the surgery, and what to expect. In the short-term (one to two years), the patient would probably have the benefit of a more normal functioning MCP joint. In the long-run, the surgeon could not predict what effect the MCP surgery would have on the trapezial-metacarpal (TM) reconstruction. In the worst case scenario, the patient could always have a joint fusion if this plan fails.

The surgeon uses this patient case to point out the deficiencies in research regarding the problem of MCP joint hyperextension in patients with arthritic TM joints. Even with the positives associated with the volar capsulodesis procedure, there are no long-term studies to show what happens down the road. Further research is needed to show if treating the MCP is helpful or a waste of time and money.
Ryan Klinefelter, MD. Metacarpophalangeal Hyperextension Deformity Associated with Trapezial-Metacarpal Arthritis. In The Journal of Hand Surgery. December 2011. Vol. 36A. No. 12. Pp. 2041-2043.