Why Does a CMC Arthroplasty for Basal Joint Arthritis Not Use an Implant?

The Counterintuitive Surgery

When I explain CMC arthroplasty to patients with basal joint arthritis, I often see confusion cross their faces. We're going to remove a bone and not put anything in its place? It sounds like we're making the problem worse, not better.

After years of knee replacement commercials and hip replacement success stories, patients reasonably expect that fixing a worn-out joint means installing new hardware. So why does thumb basal joint surgery—one of the most successful procedures in hand surgery—work differently?

The answer involves understanding what makes your thumb unique and why a missing bone can actually function better than an arthritic one.

What's Happening in Your Thumb

The carpometacarpal joint at the base of your thumb—the CMC joint, or basal joint—is where your thumb metacarpal meets a small wrist bone called the trapezium. This joint allows your thumb to move in multiple directions: bending, extending, and most importantly, opposing across your palm to meet your fingers.

This mobility is what makes human hands so capable. It's also what makes the basal joint vulnerable. Every time you pinch, grip, or grasp, significant force concentrates on this small joint. When you pinch an object between your thumb and index finger, the force at the CMC joint can be twelve times the force applied at your fingertips.

Over years, cartilage wears away. Bone grinds against bone. The joint becomes painful, swollen, and weak. Simple tasks like turning a key, opening a jar, or buttoning a shirt become difficult or impossible.

A jewelry maker from Durango described the progression vividly: "First it just ached after a long day at the bench. Then it hurt during work. Now it hurts when I pour my morning coffee."

Why Not Just Replace It?

Joint replacement works beautifully in hips and knees. Why not apply the same principle to the thumb?

Surgeons have tried—repeatedly. Over the decades, numerous implant designs have been developed for the basal joint. Some were made of silicone, others of metal or ceramic or pyrocarbon. Each new design promised to solve the problems of its predecessors.

The results have been consistently disappointing. The forces transmitted through the thumb are enormous relative to the joint's size, and implants tend to loosen, dislocate, or wear out prematurely. Silicone implants caused inflammatory reactions and bone destruction. Metal implants loosened from surrounding bone. Even newer designs have shown concerning failure rates in long-term studies.

Meanwhile, a surgery developed in the 1970s that involves simply removing the trapezium—with no implant at all—has proven remarkably durable. Decades of follow-up data show excellent outcomes lasting twenty years or more. Patients return to activities they'd abandoned, with minimal complications and rare need for revision surgery.

When something works this well without an implant, adding hardware introduces risk without proportional benefit.

How Removing a Bone Can Help

The procedure—called trapeziectomy with or without ligament reconstruction—removes the arthritic trapezium entirely. This eliminates bone-on-bone contact because one of the bones is simply gone. No bone, no grinding, no pain.

But wait: doesn't this leave a gap? Won't the thumb collapse into that empty space?

This is where the body does something remarkable. Over time, scar tissue fills the space where the trapezium used to be. This scar tissue, sometimes called a "fibrous pseudarthrosis," acts as a cushion between the remaining bones. It's not as elegant as a natural joint, but it's stable, durable, and pain-free.

The thumb does shorten slightly. Most patients lose a small amount of pinch strength compared to a normal, healthy thumb. But compared to an arthritic thumb—which was weak and painful before surgery—function improves dramatically.

A retired mechanic from Cortez told me six months after surgery, "I can finally grip a wrench again. I don't care that my thumb is a little shorter."

What the Surgery Involves

The procedure is typically performed as outpatient surgery under regional anesthesia, meaning your arm is numbed but you're not under general anesthesia unless you prefer it.

Through an incision at the base of your thumb, I remove the trapezium bone completely. In most cases, I then suspend the thumb with a suture-button device called a "tightrope", which prevents it from subsiding (or moving down) toward the empty space. This step isn't universally performed; some surgeons (usually in countries other than the United States) omit it with good results. The decision depends on factors including the patient's bone quality, ligament integrity, and the surgeon's training and experience.

After surgery, your hand is immobilized in a splint and then a removable brace for several weeks. This allows the tissues to heal and the reconstructed ligament to stabilize.

The Recovery Reality

CMC arthroplasty recovery requires patience. This surgery trades short-term inconvenience for long-term gain, and the early weeks can be frustrating.

You'll first wear a splint and then a brace for a total of four to eight weeks, during which your thumb is essentially immobilized. Hand therapy begins after 2 weeks once the splint comes off, focusing on regaining range of motion and rebuilding strength. You will receive a removable brace at this first visit with hand therapy, at 2 weeks postop. Most patients notice significant improvement by three months, but full recovery can take six months or longer.

During this period, you can't use the operated hand for much. If your dominant hand is affected, simple tasks become challenging. A teacher from Farmington scheduled her surgery over summer break specifically to avoid trying to write on a whiteboard during recovery. Planning ahead makes the process more manageable.

The initial weeks often include some swelling and discomfort, though pain is usually well-controlled with medication. What surprises many patients is how quickly the arthritic pain disappears—even while surgical healing is still occurring, the bone-on-bone grinding is gone.

Outcomes and Expectations

The success rate for CMC arthroplasty is high. Most studies report good to excellent outcomes in 85 to 95 percent of patients. Pain relief is typically substantial, and most patients return to activities they had given up.

Strength recovery varies. Many patients regain enough pinch strength for all normal activities. Some don't quite return to pre-arthritis levels, but they improve significantly compared to their painful, arthritic baseline. For patients with severe weakness before surgery, gains can be dramatic.

Complications are uncommon but can include nerve irritation, tendon problems, persistent weakness, and rarely, instability of the thumb. Serious complications requiring additional surgery are unusual.

Longevity is excellent. Unlike joint replacements that may wear out and require revision after fifteen to twenty years, trapeziectomy results tend to hold up indefinitely. Patients operated on in their fifties rarely need additional procedures in their eighties.

When an Implant Might Make Sense

I don't want to suggest that implants are never appropriate. For younger patients with high functional demands who are unwilling to accept any strength loss, newer implant designs remain an option—with appropriate counseling about the less proven track record. Some surgeons have reported good results with specific implant types in select patients.

There is a new implant, recently released in the United States called Touch. This has been used in Europe for many years, with good results. There are some concerns about this performing in the US population, which tends to be more active and with higher demands on the hands. This is currently being done in a limited number of centers, and American surgeons (including me) are eagerly awaiting results, which will take many years.

Research continues. Future implant designs or biologic treatments may eventually change the standard of care. For now, though, trapeziectomy remains the gold standard because it works reliably and durably.

The Bigger Picture

It seems counterintuitive that removing a bone could be better than replacing it. But medicine doesn't always follow intuition. The thumb basal joint operates under unique conditions—enormous forces, complex motion, and limited surrounding bone—that make it poorly suited for current implant technology.

What I've learned over my 12 years of treating basal joint arthritis is that patients care about function, not anatomy. They want to open jars, turn keys, write letters, and pursue hobbies without pain. CMC arthroplasty reliably delivers those outcomes. Whether there's a trapezium bone in there matters far less than whether the thumb works.

If you're facing this surgery, the absence of an implant isn't a limitation—it's a feature. The procedure works precisely because it doesn't try to replicate normal anatomy. Instead, it creates a new, pain-free arrangement that your body accepts and maintains for decades.

Your thumb will be different after surgery. It will also, almost certainly, be better.

You can email Doctor Butzen at doctorbutzen@gmail.com if you have questions. He may request an office visit for complex concerns that require face-to-face discussion.