Trapezio-Metacarpal Joint Arthritis of the Thumb
Trapezio-Metacarpal Joint Arthritis of the Thumb
This article describes joint arthritis of the Trapezio-Metacarpal joint of the thumb and treatment.
Hand function requires a thumb with an intrinsic stability, strength, and mobility to resist the forces by one or all four fingers during pinch or grasp. This mobility requires the thumb to be in the proper position for function and is dependent upon the trapezio-metacarpal joint. This complex saddle-shaped joint at the base of the thumb allows for abduction away from the palm, both radially and palmarly, while allowing the rotation (pronation and supination).
The forces generated from this joint are extremely high. (In fact, in simple pinch the amount of force within the trapezio-metacarpal joint is twelve times the force to the tip of the thumb). Unfortunately, this joint is the second most frequent for osteoarthritis of the hand and by rheumatoid arthritis as well. A painful, stiff, trapezio-metacarpal joint can make even the simplest tasks of daily living (turning a key, grasping a doorknob, opening a car door, buttoning a shirt, etc.) impossible.
Osteoarthritis of the Thumb
Osteoarthritis of this joint is most commonly seen in middle-age or post-menopausal women. Female prevalence of this degenerative process is most likely due to greater joint laxity which leads to increased joint incongruity. Combining joint incongruity with high frequent forces leads to an accelerated degenerative process.
1st CMC joint thumb x-ray
Physical Exam
The physical examination of a patient with trapezio-metacarpal joint problems starts with inspection. Subluxation of the trapezio-metacarpal joint is noted by a prominence at the base of the thumb and a decrease in range of motion. Patients will have increased tenderness to palpation over this area as well as painful, weak, key pinch. Finally, perform a “Grind Test”. This is where the examiner holds the thumb and applies compressive force with rotation reproducing the patient’s pain and testing for instability. If any of these tests are positive, obtain x-rays.
Eaton describes a radiographic classification in which progressive destruction and subluxation of the trapezio-metacarpal joint occur.
Stage I: This stage precedes any joint degeneration, articular contours are normal. The joint space may be widened if effusion is present.
Stage 2: Slight narrowing of the thumb metacarpal trapezial joint space is present, but the articular contours are maintained. Osteophyte formation, when present, is less than 2mm in size.
Stage 3: Significant thumb metacarpal trapezial joint destruction is present. Sclerotic or cystic changes occur in the subchondral bone. Osteophytes are larger than 2mm in size.
Stage 4: In this stage both the trapezio-metacarpal joint as well as the scaphotrapezial joint demonstrates significant degenerative changes and debris. The trapezio-metacarpal joint may have a subluxation. Cystic changes can be found in the Scaphoid, trapezium, and first metacarpal bones. Treatment for trapezio-metacarpal joint problems is based on a radiographic stage. Although, we try conservative efforts in all four stages, they are usually more successful for stages 1 and 2. Rest and nonsteroidal anti-inflammatory medications should be the
first step.
Treatment Protocols
If this fails, the treating physician may wish to try a Medrol Dose Pak, and have a custom designed splint constructed. An occupational therapist with special splint training will make a hand-based, palmar abducted, first CMC joint splint with the thumb interphalangeal joint free.
This splint gives support for the trapezial-metacarpal joint while allowing for flexion at the interphalangeal joint of the thumb. Unfortunately, most patients have difficulty tolerating this splint since it limits thumb function considerably by limiting mobilityof the trapezio-metacarpal joint. If the above maneuvering fails to improve function and pain, the next step is an injection of steroid into the trapezio-metacarpal joint. The author’s personal preference is a mix of 1cc of Celestone. Obtain X-rays if there are any difficulties.
Injections
h 1cc of Xylocaine. Apply traction to the thumb while palpating the base of the first metacarpal. Advance a 25-gauge needle into the joint and the solution
The injection will usually resolve the pain due to early stages of arthritis; advanced stages may have no improvement. If there is no improvement in pain despite the above conservative efforts, the next step would be to consider surgical intervention. There are many different techniques available to address trapezio-metacarpal arthritis. With long-term follow-up there is clearly one superior technique. In the late 1970’s and 1980’s there was much enthusiasm with silicone implant arthroplasty, resurfacing the base of the first metacarpal while replacing the trapezium.
Follow Up Studies.
In a follow-up study of 32 patients with an average follow-up at 3.9 years, there was a twenty-five percent failure rate.4,5 The high failure rate was due to silicone cold flow and wear, subluxation, and reactive giant cell synovitis. Despite the fact that silicone arthroplasty has been highly successful in the metacarpal phalangeal joints of the index, middle, ring, and small digits, it has failed in the trapezio-metacarpal joint of the thumb. The technique that has proven successful with greater than 10 year follow-up is the flexor carpi radialis ligament reconstruction with tendon interposition arthroplasty.
In this technique removes a part of or all of the trapezius. Then, the flexor carpi radialis tendon is taken through the case of the thumb metacarpal. The tendon is then brought back to itself at the base of the thumb metacarpal. The tendon is then brought back to itself at the base of the trapezial trough. Then folded like an accordion filling the space once occupied by the trapezius. This technique restores stability of the thumb while also constructing an arthroplasty with local tissues. Long-term follow-up outcome study has shown a ninety-five percent excellent relief of pain while also restoring thumb function.
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