Thumb osteoarthritis, also known as rhizarthrosis, is a degenerative joint condition that involves the progressive degradation of cartilage at the base of the thumb, where the wrist bone called the trapezium meets the first bone of the hand, the metacarpal. This cartilage degradation can lead to pain, stiffness, and reduced joint function in this area. Thumb osteoarthritis is more common in women and generally develops from the age of 50. Repetitive activities and natural wear and tear related to aging are factors that can contribute to the development of this condition. It can be well tolerated despite severe radiological indicators and thumb alterations, or it can become very disruptive in daily life, causing painful sensations, restricted mobility at the base of the thumb, and weakened grip strength of the hand. The predisposing factors for this condition are varied: degenerative as in all osteoarthritis, mechanical (repetitive thumb movements), hereditary and familial, sometimes following trauma. Over its progression, which occurs gradually over several years, rhizarthrosis leads to gradual thumb stiffness that hinders the ability to grasp large objects, causing a decrease in strength and sometimes an unsightly deformity called “Z-thumb.” This condition can also cause deformation of the middle joint of the thumb (the metacarpophalangeal joint), which may lose flexibility and deform at times. The initial treatment is medical, involving the use of analgesics and anti-inflammatories, anti-osteoarthritis medications, sometimes joint injections, and primarily, the use of a resting splint (orthosis). This orthosis is generally worn at night, either temporarily or permanently. Surgeryis only considered after the failure of medical treatment.
- The resection of additional tendons at the base of the thumb does not affect osteoarthritis and has no impact on its progression. It can have a positive effect on pain in the early stages.
- In specific cases, immobilization of the joint (arthrodesis) may be proposed.
- Some opt for the removal of the trapezium and stabilization of the thumb using a neighboring tendon.
- Dr. De Smet, in more advanced stages, suggests the implantation of a new generation prosthesis.
TOUCH®, a dual mobility metacarpal prosthesis
- 1st prosthesis to offer a spherical and conical cup
- High modularity: 144 possible combinations to closely match the patient’s anatomy
- Complete ancillary with integrated bone box
Frequently performed under regional anesthesia, these procedures can be done during a brief hospitalization (outpatient) or over a few days, as these interventions are often associated with some pain. All these operations require a variable period of immobilization (ranging from 15 days to 6 weeks). Procedures involving the replacement of the trapezium generally have a prolonged recovery period. However, these interventions never fully restore a normal thumb nor allow complete recovery of hand grip strength, despite often prolonged rehabilitation. There are always risks of complications:
- Local infection is rare, but in some cases, antibiotics may be necessary to prevent it. In case of infection, a new intervention may become necessary.
- A swollen, painful, sweaty hand, followed by stiffness, is cause for concern (algodystrophy syndrome). The evolution of this condition can be prolonged, extending over several months or even years. Sequelae are possible (residual pain, slight stiffness of fingers and/or wrist, sometimes even of the shoulder).
- Tingling, numbness of the thumb may occur due to irritation of the small nerves of the thumb (sensory branches of the radial nerve). These sensations usually disappear within a few days to a few weeks, although they may persist. Nerve transection is very rare.
- Joint prostheses are made from materials that wear out over time. The rate of wear depends on your activity level. Metal prostheses are often fixed with cement, which can detach from the bone over time (loosening). Wear or loosening may require subsequent surgical intervention.
