Trapeziometacarpal (TMC) arthritis ( also known as Rhizarthrosis ) is arthritis of the first carpometacarpal (CMC) joint of the thumb. The CMC joint of the thumb (pollex), or TMC joint plays a critical role in the normal functioning of the thumb. It is the most important joint connecting the wrist to the metacarpus. Osteoarthritis of the TMC is a severely disabling condition; up to twenty times more common among elderly women than in average.
Believed causes of TMC arthritis are: excessive repetitive use of the CMC joint of the thumb; a subluxation; a lesion of the ligaments or a fracture.
Laxity of the CMC joint is a key factor in causing TMC arthritis. The laxity, which can be hereditary, results in an increased risk for ligament injuries. These injuries are regarded as a primary stimulus in the development of arthritis. Laxity of the CMC joint also causes a hyperextension, which is another primary stimulus for the development of arthritis.
Another common cause for TMC arthritis is weakness of the cross links of the fingers (ligg. oblique anterior). These ligaments are the most important stabilisers of the fingers. 
The first signs of arthritis in the thumb are
- pain, tenderness, and stiffness at the base of your thumb. This occurs with gripping, pinching, or clasping something between the thumb and index fingers or when a mild force, such as when you twist a key in a lock or turn a door handle. An ache after activity can also be a feature.
- Decreased strength and range of motion eg opening jars or doing up buttons may become difficult.
- Appearance. The joint may become swollen or develop a bony bump. The joint may appear squarish and enlarged.
- Noticeable lumps or swelling on the first CMC joint
- Thumb CMC grind test
- Plain radiographs showing degenerative changes (bone spurs, thinning of cartilage, loss of joint space)in affected joints are usually diagnostic.
Conservative measures are the first options for CMC arthritis and can ameliorate symptoms in most cases. These include
eg Try to avoid: clenching your hands when carrying things; repetitive movements that involve pinching or twisting
- range-of-motion and stretching exercises to improve thumb motion.
- Advance to include strength exercises for the thumb and fingers.
- Dexterity and fine motor exercises for the hand and thumb. 
- Application of therapeutic heat or cold
- Application of electro therapeutic techniques eg Therapeutic US, TENS. US has been found to have the ability to evoke a broad range of therapeutically beneficial such as improved pain and functional outcomes, positive cartilage healing properties and positive phonophoresis for hyaluronan. 
- Acupuncture. May work in pain relief for some people.
- Splinting, designed to help reduce pain, prevent deformity, or prevent deformity from getting worse. To wear at night, during flare ups and when doing heavy work with hand.
- Clinical trials have provided evidence that a combination of joint mobilization, neural mobilization, and exercise helps with CMC joint pain.
Topical medications, such as capsaicin or diclofenac, which are applied to the skin over the joint
Over-the-counter pain relievers, such as acetaminophen, ibuprofen or naproxen sodium
Prescription pain relievers, such as celecoxib (Celebrex) or tramadol (Conzip, Ultram)
Injections. Corticosteroid injections can offer temporary pain relief and reduce inflammation.
If the diagnosis of ‘rhizarthrosis’ is determined too late, none of the above treatments will be helpful. Because of severe pain and movement restriction, surgery could be inevitable.
- Wikipedia. CMC joint. Available from: https://en.wikipedia.org/wiki/Carpometacarpal_joint (last accessed 13.4.2019)
- Mayo clinic. Causes remedies for thumb arthritis. Available from: https://www.youtube.com/watch?v=iVbOPCu5Ius. (last accessed 13.4.2019)
- Wolf JM, Schreier S, Tomsick S, Williams A, Petersen B. Radiographic laxity of the trapeziometacarpal joint is correlated with generalized joint hypermobility. The Journal of hand surgery. 2011 Jul 1;36(7):1165-9. Available from: https://www.jhandsurg.org/article/S0363-5023(11)00353-4/abstract (last accessed 14.4.2019)
- A. Gondim Teixeira, Pedro & Omoumi, Patrick & J Trudell, Debra & Ward, Samuel & Blum, Alain & L Resnick, Donald. (2010). High-resolution ultrasound evaluation of the trapeziometacarpal joint with emphasis on the anterior oblique ligament (beak ligament). Skeletal radiology. 40. 897-904. 10.1007/s00256-010-1068-0. Available from: https://www.researchgate.net/publication/49647832_High-resolution_ultrasound_evaluation_of_the_trapeziometacarpal_joint_with_emphasis_on_the_anterior_oblique_ligament_beak_ligament
- Healthline. Basal joint arthritis. Available from: https://www.healthline.com/health/basal-joint-arthritis#symptoms (last accessed 14.4.2019)
- Mayo clinic. Thumb arthritis. Available from: https://www.mayoclinic.org/diseases-conditions/thumb-arthritis/diagnosis-treatment/drc-20378344 (last accessed 14.4.2019)
- Healing hands rehab. CMC arthritis. Available from: https://www.youtube.com/watch?v=wCIA1_tksjA&feature=youtu.be (last accessed 14.4.2019)
- LB hand therapy. Thumb stability exercises. Available from: https://www.youtube.com/watch?v=rf4R7udarNg&feature=youtu.be
- Central physiotherapy. Arthritis of the thumb. Available from: https://www.centralphysicaltherapy.com/Injuries-Conditions/Hand/Hand-Issues/Arthritis-of-the-Thumb/a~282/article.html (last accessed 14.4.2019)
- Srbely JZ. Ultrasound in the management of osteoarthritis: part I: a review of the current literature. The Journal of the Canadian Chiropractic Association. 2008 Mar;52(1):30. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2258240/ (last accessed 15.4.2019)
- Arthritis Foundation. Acupuncture and osteoarthritis. Available from: https://www.arthritis.org/living-with-arthritis/treatments/natural/other-therapies/mind-body-pain-relief/oa-acupuncture.php (last accessed 15.4.2019)
- Jospt. The Effectiveness of a Manual Therapy and Exercise Protocol in Patients With Thumb Carpometacarpal Osteoarthritis: A Randomized Controlled Trial. Available from: ☀https://www.jospt.org/doi/full/10.2519/jospt.2013.4524 (last accessed 14.4.2019)
- Dartmouth-Hitchcock. Basal joint arthritis. Available from: https://www.youtube.com/watch?v=iSA1BSSQLPA (last accessed 15.4.2019)