Base of thumb Osteoarthritis
Symptomatic osteoarthritis at the base of the thumb is very common, affecting 11% of males and 33% of females over the age of 50. Review of thumb carpometacarpal arthritis classification, treatment and outcomes – PMC. With the highest prevalence in postmenopausal women in their fifth and sixth decades of life. The osteoarthritis affects the carpometacarpal (CMC) joint and/or the scaphotrapeziotrapezoid (STT) joint. The CMC is most commonly affected, and its articulations are between the metacarpal bone of the thumb and the trapezoid. While the STT is a multi-faceted joint containing articulations between the scaphoid, trapezium and trapezoid bones.
The 1st CMC joint allows for a large range of movement and is important for normal hand function and general dexterity. With aging, strenuous use and/or previous trauma, the supportive ligamentous structures of the joint can become lax. This leads to increased stress loads through the CMC joint, causing cartilage loss, bony impingement and pain.
Despite thumb osteoarthritis increasing prevalence radiographically in the ageing population, many patients will not develop clinical symptoms. Studies show a poor correlation between the severity of osteoarthritis visible in the CMC and STT on x-ray and the level of pain or functional impairment experienced by the patient. Thumb carpometacarpal arthrosis – ScienceDirect
What are the signs and symptoms?
In symptomatic cases patients will complain of localised pain around the base of the thumb and into the thenar eminence. Symptoms are progressive and typically develop over months to years. The pain is worse with activities such as opening jars, turning keys and lifting heavy saucepans or kettles. Loss of movement in the thumb is often present but is not always noticed by the patient.
Patients will have focal tenderness over the CMC articulation and into the radial snuffbox for STT arthrosis. The grind test will usually be symptomatic, which involves an axial compressive force through the CMC to provoke symptoms. Diagnostic value of clinical grind test for carpometacarpal osteoarthritis of the thumb – PubMed
How is it diagnosed?
The diagnosis of thumb osteoarthritis will be made from a combination of your clinical history, examination findings and a plain film X-ray.
X-rays will confirm the changes and the severity. Ultrasound is not typically used in the workup but can be helpful in excluding other potential causes of your radial-sided wrist/thumb pain. MRI can also confirm the changes but is not typically required in the workup of osteoarthritis.
How are they treated?
Treatment options are divided into conservative and surgical.
Conservative options:
- Activity modification, ergonomic modifications, +/- analgesia/short course of NSAIDs. These simple interventions can be helpful initially, allowing things to calm down. For tradesmen, fitting their tools with a bigger grip can often reduce the symptoms enough to allow them to continue to work and help with general dexterity. A spica splint can also be helpful to support and unload the joint. The effects of hand splinting in patients with early-stage thumb carpometacarpal joint osteoarthritis: a randomized, controlled study – PMC
- A local anaesthetic and steroid injection into the 1st CMC/STT joint, typically under ultrasound guidance to confirm intra-articular location, are often helpful at easing some of the inflammation and pain associated with osteoarthritis. The Efficacy of Intra-Articular Versus Extra-Articular Corticosteroid Injections in the Thumb Carpometacarpal Joint – Journal of Hand Surgery Global Online Duration of benefit will vary in individuals, ranging from weeks to a number of months or longer.
Surgical options:
If conservative options mentioned previously do not provide adequate relief or if there is already substantial arthrosis on a plain film X-ray at the time of initial presentation, then there are surgical options. These include arthrodesis (fusion), trapeziectomy (removal of the trapezium) or arthroplasty (joint replacement surgery). Which one is the most appropriate for you will be a discussion with a wrist and hand surgeon.
- Arthrodesis is typically reserved for younger, high-demand patients that have failed conservative options. Fusion offers additional stability with lower complication rates in this patient population. Carpometacarpal Arthrodesis: Indications and Techniques – PubMed
- Trapeziectomy +/- ligament reconstruction is the most common surgical procedure and is usually indicated in older, less demanding patients. Benefits include better-preserved thumb movements, helping with dexterity and general day-to-day use. Trapeziectomy for trapeziometacarpal osteoarthritis – PubMed
- Arthroplasty is another option that achieves excellent outcomes, with earlier functional gains compared to trapeziectomy but with higher implant-specific complications and revision rates. Trapeziectomy Versus Carpometacarpal Arthroplasty for Basilar Thumb Arthritis: A Narrative Review of Comparative Outcomes – PMC
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