‘Teabag’ implant for arthritis in thumbs

Spongy discs made from the same material used to make teabags may offer a new way to treat arthritis of the thumb. The discs are surgically implanted between the two bones of the joint in a 30-minute procedure under local anaesthetic.

As well as immediately acting as a cushion, over time repair cells penetrate tiny holes in the discs, forming a strong fibrous tissue that strengthens the joints, increasing movement and reducing pain.

A new study involving 20 people conducted at Southend University Hospital and published in the medical journal Hand Surgery and Rehabilitation, shows that the patients’ grip and pinch strength after the surgery were as good as healthy thumbs.

now another trial involving 27 people with thumb arthritis is under way.

Around one in five people aged 55 and over has osteoarthritis of the thumb (affecting the joint at the base of the thumb), and it causes more pain and disability than arthritis in other joints on the hand.

osteoarthritis occurs when the cartilage that protects the connecting ends of the bones becoming damaged or worn away, usually because of ageing and cumulative wear and tear.

AS a result, the bones grate against each another. The most common surgical treatment for thumb arthritis is fusing together the two bones on either side of the joint. However, this can reduce flexibility and restrict movement.

Another option is to completely remove the trapezius, the bone at the bottom of the joint. This relieves pain but can cause significant loss of grip strength.

The new implant may offer a new solution. The circular disc is made from polylactide, a material manufactured from corn starch or cane sugar and already used in a number of products, including plastic bottles and a polylacticacid yarn that is often used in teabag manufacturing.

As the disc is spongy, it acts as a cushion, but because it is also porous it attracts new cells to grow into it, so it works as a scaffold, too.

over two to three years it dissolves harmlessly.

The newly formed tissue is not as strong as the original cartilage but is tough enough to restore normal mobility.

greg packer, a consultant orthopaedic surgeon at Southend University Hospital, who was the senior author of the study, says it takes nine to 12 months for treated thumbs to be as good as a healthy thumb.

Commenting on the research, Roger Hackney, a consultant orthopaedic surgeon at the Spire and nuffield hospitals in Leeds, says similar techniques have been tried before but have failed because the newly formed tissue has disintegrated over time causing a return of pain and loss of function.

‘if this graft can be shown to be intact at five to ten years with no pain or bone loss it will be a big help to a lot of sufferers,’ he says.