What in the world is an anchovy arthroplasty anyway? It sounds like something

one would order from the local pizzeria. 

Well, no, it’s not on the list of toppings for a thin-crust, hand-tossed, or anything like that.

So, what is it?

Anchovy arthroplasty is, actually, the term given to a surgical procedure that many people have undergone, and many more may eventually need to have. It is a form of treatment for advanced degenerative arthritis of the base of the thumb.

Many of you over the age of 50 are beginning to experience pain, swelling and a “grinding” sensation in the small joint located at the base of your thumb. You may also have noticed a slow, but progressive, enlargement of that joint.  Thumb-related movements may be getting more and more difficult to perform, and getting weaker.

What you have is called “CMC joint arthritis”.

What is that?

The bones in the human hand are comprised of long, metacarpal bones and the smaller, carpal bones. Each metacarpal in the hand articulates (comes in contact with) a carpal bone creating a carpo-metacarpal joint.

The carpal bone that sits adjacent to the base of the first metacarpal (the one in your thumb) is called the trapezium, and the joint formed by it and the first metacarpal bone is the first carpo-metacarpal joint (CMC).

For any number of reasons; age, job duties, over-use, trauma or just “life” itself, this joint can wear out and become very arthritic. In fact, the arthritis can become so chronic and severe that the joint can experience subluxation (partial dislocation) or dislocate altogether, making for significant difficulty in gripping and holding objects.

If you look at the x-ray, notice the base of the thumb. The bones of the first (thumb) metacarpal and the trapezium are literally rubbing together because of severe joint destruction. Little, if any, joint space remains.

So, what’s this “anchovy” thing?

There are several different types of treatment for disabling arthritis of this joint, ranging from cortisone injections and bracing, to artificial implants. One surgical procedure commonly performed is the Anchovy Arthroplasty.

The surgery consists of the removal of the degenerated trapezium bone, effectively removing one half of the arthritic joint. 

It can’t hurt if it isn’t there, right?

Once the bone is removed, something must be done to deal with the empty space left behind.  If nothing was done, the thumb would become de-stabilized, “floppy” and literally useless. 

Next, a small tendon is harvested from the palm side of the wrist and forearm and transferred to the space next to the thumb. The tendon is then “balled up” in such a fashion as to resemble, you guessed it, an “anchovy”. 

The tendon is then stabilized in the space by various means of attaching it to the thumb metacarpal. The insertion of this tendon creates a type of “soft joint” where the trapezium used to be and provides additional stability to the base of the thumb.

The hand and thumb are placed into a cast for several weeks to heal, followed by graduation into some kind of bracing for a period of time.

So, if you are plagued by relentless pain, grinding and difficulty using your thumb, you may have “CMC” arthritis, and may be a candidate for anchovy arthroplasty. 

Don’t let arthritis give you a “thumbs down”.

Chisholm’s expertise in nursing, orthopedics and surgery spans more than 30 years. He holds multiple national certifications in these specialties. His goal is empowering people through education and information to become more engaged, proactive and responsible in their orthopedic health, and health care.