Let’s Talk About Cartilage and Arthritis
The opposing bone surfaces of our joints are covered with a layer of specialized tissue known as hyaline cartilage. This cartilage tissue allows for nearly frictionless gliding of the joint surfaces against one another. When this layer is intact and healthy, the motion of the joint is smooth and painless.
The body’s joints produce more of this cartilage during the growth of the skeleton, but once we reach adulthood no more hyaline cartilage is produced. When skeletal maturity is reached the focus of the supporting cells in the cartilage is to preserve and sustain the cartilage layer.
Because the joints stop producing more cartilage in adulthood, any damage to the joint surface or to the cartilage layer can begin a slow degenerative process of the cartilage we refer to as arthritis. There are many types of arthritis that differ in how they injure the cartilage layer. The main categories of arthritis include osteoarthritis (the most common type), inflammatory arthritis (includes many subtypes, of which rheumatoid arthritis is one), and post-traumatic arthritis which is the result of direct injury to the joint.
The Basal Thumb Joint: Basic Anatomy and Definition
The basal thumb joint is also known as the first carpometacarpal joint (1st CMC joint). This is the joint where the thumb connects with the wrist through its contact with one of the small wrist bones known as the Trapezium. The opposing surfaces of this joint are shaped like saddles that fit together, with one saddle stacked upside-down on top of the other saddle. The result is a joint that has a very large range of motion in several different directions and is capable of transitioning smoothly from one direction to another to accomplish a wide arc referred to as circumduction.
The thumb’s primary function is to form a “post” against which the fingers can push in order to pinch or grasps objects of varying sizes. The force applied against the tip of the thumb is transmitted and magnified to the basal joint, where the force is concentrated.
The combination of a wide range of motion and concentration of loading forces leads to high stresses on the cartilage of the basal thumb joint. This can lead to slow progressive damage to the cartilage layer of the joint and the development of arthritis. Any additional factors that affect the stability of the joint or that increase the concentrated force at the cartilage layer can speed up the process of cartilage damage and, ultimately arthritis.
Symptoms of Basal Thumb Arthritis
The primary symptoms of arthritis are pain and loss of motion but can also include swelling and warmth. Because the thumb is such an integral part of normal hand function, pain and loss of motion in the basal thumb joint can affect many simple daily activities, such as preparing food and getting dressed. Work and other activity-related functions are also affected. People often experience pain with activities that repeatedly bring the thumb against the side of the index finger in a pinching type mechanism, as well as twisting motions such as opening jars, bottles or twisting doorknobs.
Loss of the thumb’s normally wide range of motion can make it increasingly difficult to grasp larger objects as well as pick up small items with a fine pinch of the thumb tip to the index finger. People may also experience grinding or “popping” of the joint as the rough joint surfaces shift past one another rather than the normal gliding motion.
Are There Treatments for Basal Thumb Arthritis?
Currently there is no proven treatment that can replace or restore the normal cartilage layer of a damage joint surface. Therefore, treatment goals are aimed at pain relief. We can target pain relief either with medications or with surgical procedures.
Medical Treatment for Basal Thumb
Medications include those that are taken orally, those applied topically, and those administered through joint injections. The most common oral medications are from the non-steroid anti-inflammatory drug class (NSAIDs) and include both over-the-counter and prescription-only medications.
Over-the-counter options in this class include ibuprofen, naproxen, and aspirin. Prescription options commonly include meloxicam and celecoxib, as well as others. Prescription medications are often more selective and therefore, protective for the stomach, or these medications can be more potent. NSAID medications can affect the kidneys and the stomach.
To protect against this risk, it is important to take these medicines with food to protect the stomach and focus on staying well hydrated to protect the kidneys. It is also important to take the lowest effective dose possible and consider using it intermittently if possible.
Any underlying stomach or kidney problem is a contra-indication to taking these medications. Acetaminophen, or Tylenol, is another oral medication that can help with arthritis pain through a different mechanism than NSAIDs and does not affect the stomach or the kidneys. High doses can affect the liver, and any underlying liver illness is a contra-indication to taking acetaminophen. Acetaminophen can be taken by itself or can be combined with other medications, such as NSAIDs, to maximize the efficacy of both medications.
Topical Medications for Basal Thumb
There are many topical medications on the market. Many of these affect the transmission of the nerve pain pathways by creating other sensory input such as a “burning” sensation that can be interpreted as more pleasant than the pain of arthritis. These types are tolerated to varying degrees by different people, but they are low risk.
Other topical medications are simply a skin-surface-applied version of an oral medication such as diclofenac gel. This gel works by the same mechanism as oral NSAIDs but has lower risk due to lower doses applied locally over the painful area and lower levels in the bloodstream. Topical medications are generally lower risk and, therefore, a good option to try initially.
Injectable Medications for Basal Thumb
Injectable medication typically refers to injectable corticosteroid, or simply “steroid”, into the affected joint. Steroid medications are the most potent anti-inflammatory medications available. The injectable form allows the medication to be delivered directly to the affected joint without traveling through the bloodstream and therefore minimizes system-wide side effects.
Not everyone will get relief from steroid medications, but for most patients, steroid injections reliably offer significant pain relief from arthritis pain, and this pain relief can often last for 4-6 months on average. These injections can be safely repeated up to 3 or 4 times if desired.
However, the long-term consequences of chronic, multiply repeated steroid injections include weakening of the tissues of the joint such as ligaments, tendons, and even the bone underlying the joint surface, as well as thinning of the skin and normal subcutaneous fat layer. In some cases, the skin can become depigmented or lose some of the normal skin color. For people with diabetes, steroid injections often cause a short-term rise in blood sugar levels despite good medical management. This usually returns to baseline after a week or two.
Adding a specialized brace can enhance the degree or duration of pain relief obtained with any of these medication choices. There are several companies that produce highly specific braces that focus on the basal thumb joint without interfering with wrist motion and allow much normal movement of the thumb distal joints. Because they are highly specific, they are very functional. Like many of the previously mentioned options, some people will not find these beneficial or may be unable to tolerate them.
Surgical Treatment for Basal Thumb Arthritis with St.George Hand Surgery
Surgical treatment is aimed at reconstructing or replacing the joint surfaces. There are many surgical procedures for basal thumb arthritis in use today, and most offer reliable pain relief and preservation of function. Each type of reconstruction has potential drawbacks and may differ in how much of the joint is replaced. The most common approach is to remove a part, or all of the Trapezium bone, followed by stabilization and support of the thumb using a tendon borrowed from the forearm.
There are several tendons that make a good donor choice because of redundancy with several muscle-tendon units sharing a function. Successful outcomes from these types of reconstructions can be expected 90-95% of the time when considering the degree of pain relief and preservation of function.
Surgical recovery can take 3-6 months and involves a stepwise progression of pain relief and gradually improving function. Working with a hand therapist during recovery is an integral part of maximizing functional outcome.
Our St George hand and wrist surgery experts can help you get to the root of your pain, and find a solution to help you get pain-free. The hand surgeons at Intermountain Healthcare’s Southwest Orthopedics and Sports Medicine specialty clinic specialize in providing the highest quality care, with kindness and compassion. Whether you’ve already been diagnosed with Basal Thumb Arthritis or are still looking for a diagnosis, we are here to help. Schedule an appointment today to get started.
Written by: Dirk Slade, MD
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