2 The procedure

2.1 Indications

2.1.1 Osteoarthritis of the hand joints is a common condition that deteriorates over time, although the severity of symptoms, rate of deterioration and functional effects are variable. Artificial trapeziometacarpal (TMC) joints are primarily used to treat the pain of severe end-stage osteoarthritis.

2.1.2 Conservative treatments for osteoarthritis of the hand include anti-inflammatory and analgesic medication, and steroid injections. Other treatments include complete joint excision without replacement (also called excision arthroplasty), native graft arthroplasties (in which the patient's own tissue, typically tendon, is interposed in the space left after joint excision) and fusion of joints (arthrodesis).

2.2 Outline of the procedure

2.2.1 A general anaesthetic is usually used and a tourniquet is applied to the affected arm to maintain a blood-free operation site. An incision is made over the diseased joint and the tendons are retracted. The joint is removed with an oscillating saw, and a prosthetic joint (typically made of a silicone-based material) is inserted in its place. A splint is applied to the fingers.

2.3 Efficacy

2.3.1 The five studies reviewed described a total of 257 patients. In one small randomised controlled trial comparing silicone prosthesis arthroplasty with tendon arthroplasty, the proportion of satisfied patients was similar in the two groups (80% versus 85%; 12/15 and 11/13 patients, respectively). The mean pain reduction was also similar in both groups of patients. A non-randomised comparative study of 89 patients reported significantly less pain at 12 months in 50 joints treated with a silicone prosthesis arthroplasty, compared with 54 joints treated with sling excision arthroplasty (p < 0.01). Patients in the silicone prosthesis group reported better function for most tasks (statistically significant for being able to carry a milk bottle and taking off the handbrake of a car), but there was no statistically significant difference in patient satisfaction between the two groups. A case series of 58 patients with a mean follow-up of 16 years reported that maximal improvement was achieved at 5 years. A small case series reported that 88% (22/25) of patients had less pain than before the procedure after a mean follow-up of 6.5 years. For more details, refer to the Sources of evidence section.

2.3.2 The Specialist Advisors considered that the long-term benefits of this procedure need to be compared with the long-term benefits of established procedures such as excision arthroplasty and joint fusion.

2.4 Safety

2.4.1 Four studies comprising a total of 242 patients reported on safety of the procedure. In three studies, between 6% (4/62) and 20% (6/30) of implants had to be removed. The reasons for removal were listed as subluxation, fracture, dislocation, infection, pain, stiffness, and silicone synovitis. One study of 90 patients reported that components loosened in 16% (13/79) of replacement joints after a mean follow-up period of 6 years. Two studies reported that a small number of patients had reflex sympathetic dystrophy after the procedure (3% [2/58] and 4% [1/25] of patients). For more details, refer to the Sources of evidence section.

2.4.2 The Specialist Advisors considered that the main potential adverse effects include infection, stiffness, nerve injury, silicone synovitis and failure of the joint replacement.