Rhizarthrosis (or osteoarthritis of the base of the thumb) corresponds to trapezium-metacarpal osteoarthritis. It is the most common arthrosis encountered in the hand, along with arthrosis of the distal interphalangeal joints (last joint before the pulpal end of a finger).
It affects one woman in six from the age of 50 and often affects both sides at different stages of arthrosis.
The symptoms of Rhizarthrosis.
Most often, osteoarthritis is linked to a genetic predisposition. However, it can be the consequence of a fracture, an infection (arthritis) or an inflammatory rheumatism (rheumatoid arthritis).
It is estimated that Rhizarthrosis will only become symptomatic in 20% of cases.
The essential symptom, the reason for the consultation, remains the pain, not very important at the beginning, which can evolve towards more persistent pain occurring during daily activities using the thumb-index clamp (handling small objects, turning the key of a door...). These pains will be accompanied little by little by a deformation of the joint which ends up subluxing: a characteristic deformation of the base of the thumb appears, called Z thumb. This deformation is accompanied by a difficulty in opening the 1st commissure (angulation between the 1st and 2nd rays), i.e. to spread the thumb.
Treatment of rhizarthrosis
Initially, the treatment is medical:
Wearing a custom-made thermoformed night orthosis
The use of local anti-inflammatory drugs, taken orally, and as a last resort by infiltration of coticoids after, most often, several years of evolution
- viscosupplementation with hyaluronic acid
Physiotherapy: electrotherapy, ultrasound, icing.
These different techniques usually allow to gain several years before reaching a surgical solution. On the other hand, when these treatments, which have been well conducted for six months to a year, remain insufficient, an intervention must be considered earlier.
Surgical treatment of Rhizarthrosis
2 types of intervention can be proposed: trapezectomy and trapeziometacarpal prosthesis
The type of surgery required depends on many parameters: the patient's age, activity level, degree of osteoarthritis...
It is performed under loco-regional anesthesia as an outpatient procedure. It allows a return to indolence and a satisfactory mobility sector. It has the advantage of obtaining a definitive result (unlike trapezoid-metacarpal prostheses which may require a change due to wear), but the disadvantage of a longer recovery period (between three and six months), unlike the prosthesis where recovery is faster (between six weeks and two months).
The trapezium-metacarpal prosthesis:
This prosthesis looks like a miniaturized hip prosthesis. As with trapeziectomy, a postoperative immobilization of three to four weeks is necessary. Recovery is faster (six weeks to two months). The trapezium-metacarpal prosthesis has the disadvantage of all prostheses, namely wear and tear over time, which may require a prosthetic change.