Thumb arthroplasty

Thumb arthroplasty, or rhizarthrosis surgery, is a hand surgery procedure indicated when the pain associated with rhizarthrosis becomes too severe and can no longer be relieved by medical treatment. Rhizarthrosis is located at the base of the thumb, between the first metacarpal bone and the trapezium. It is caused by wear and tear of the articular cartilage, leading to pain and progressive deformation of the thumb, and lack of strength when holding an object or opening a bottle, for example. Arthritis of the thumb is very common, especially around the age of 50, and affects more women than men.

Rhizarthrosis surgery aims to reduce pain and restore thumb function, thus improving patients’ quality of life.
There are 2 main techniques: prosthetic arthroplasty, which replaces the damaged joint with a prosthesis, and trapezectomy, which removes the trapezium and stabilizes the thumb with a tendon.

In very early forms, it is possible to cut a strip of tendon at the base of the thumb, to reduce pain without compromising future surgery.

The decision to undergo thumb arthroplasty depends on a number of factors, not least the discomfort caused. Patients suffering from rhizarthrosis of the thumb often experience intense pain, reduced grip strength and significant limitations in their daily activities.

When conservative treatments such as anti-inflammatory drugs, rest splints, occupational therapy and injections are no longer sufficient to relieve pain, surgery may be considered.

The type of surgery depends on the patient’s age, type of physical and occupational activity, and the radiological stage of osteoarthritis.
Prosthetic arthroplasty and trapezectomy are effective options for treating pain.

Dr. Bejic performs thumb arthroplasties at Nyon Hospital or Clinique de Genolier, under local anesthesia (axillary block) or general anesthesia. The patient remains in hospital for 24-48 hours for post-anaesthetic monitoring.
Post-operative follow-up and hand rehabilitation are carried out at the Leman Hand Clinic, in close collaboration with the occupational therapist, Elise.

Two main thumb arthroplasty techniques are used to treat rhizarthrosis: prosthetic trapeziometacarpal arthroplasty and trapezectomy (non-prosthetic arthroplasty). Each technique is chosen according to the patient’s individual needs, the severity of the thumb osteoarthritis, and expectations in terms of recovery.

Prosthetic arthroplasty involves replacing the damaged joint with a prosthesis, providing a new articular surface, thereby eliminating pain, realigning the thumb in its axis and restoring its function.
This method is particularly effective for active patients with moderate to advanced osteoarthritis of the thumb, who require rapid recovery.

The operation is performed through a 3 cm incision at the base of the thumb. The osteoarthritic deformity of the joint is resected, and a 3-component modular prosthesis is implanted by impaction. It consists of a cup in the trapezium bone, a stem in the first metacarpal bone, and an intercalary component called the “head-neck”, whose variable size and angle enable the correct tension to be adjusted. The prosthesis is made of stainless steel, coated with titanium and a layer of hydroxyapatite.

The life expectancy of these prostheses is around 15 years. Wear and tear of the prosthesis, and secondary loosening, will occur earlier the greater the mechanical stress on the thumb.

Trapezectomy involves removal of the trapezium bone, combined with ligamentoplasty, a technique that uses a tendon to stabilize the joint. It is performed through a 3 cm incision at the base of the thumb.

After removal of the trapezium, interpositional fibrous scar tissue forms naturally, replacing the removed bone and improving thumb mobility. This method can be used in patients with more diffuse osteoarthritis, notably between the scaphoid and trapezium, but it does not correct thumb deformity and often results in a loss of pinch strength.

Complications during surgery

• Injury to a sensory nerve on the back of the thumb, hematoma, infection.
• Fractures of the 1st metacarpal or trapezium during implant impaction can occur in bone weakened by osteoporosis. This unpredictable complication may force the surgeon to change surgical technique during the operation, as it is not always possible to fit the planned prosthesis.

Complications remote from the operation:

• Algodystrophy (swollen, red, painful hand with limited finger mobility) is associated with all surgical procedures (approx. 5% of patients with hand injuries or operations).
• Dislocation or dislocation of the prosthesis may occur, especially in the first few months, sometimes necessitating further surgery.
• Stiffness of the prosthesis due to ossification is rare.
• Incomplete correction of thumb deformity if the rhizarthrosis is old.
• Sinking of implants when the bone is very fragile, as in osteoporosis.
• An allergic reaction to the metal of the prosthesis may exceptionally occur, with pain and a red scar: any reaction to costume jewelry (nickel allergy) should be reported preoperatively.

Convalescence time may vary, but most patients return to full normal activities within 2 to 6 months. Pain relief is provided by painkillers, usually of moderate intensity.

After a thumb prosthesis, the patient is fitted with a custom-made protective splint for the night and for high-risk activities, which he keeps on until the sutures are removed (2 weeks). Activities are resumed progressively, depending on pain.

After trapezectomy, the patient remains in a thumb immobilization splint for 4 to 6 weeks, and then begins progressive rehabilitation with the help of the occupational therapist.

The success of thumb osteoarthritis surgery depends on a number of factors, including the severity of the osteoarthritis and the patient’s commitment to post-operative rehabilitation.

The results of thumb arthroplasty are generally very positive, with significant improvement in pain and thumb function. Patients report increased grip strength and a better ability to perform daily activities without pain.

Useful links :

• Information Sheet from the French Society for Hand Surgery
• Information Sheet – Trapeziometacarpal Prostheses in Thumb Osteoarthritis
• Touch Prosthesis