Tiny rake to repair crumbly old knees by collecting stem cells from the joint

A rake-like device that sweeps up cells could give new life to arthritic knees. 

It collects stem cells — which can form new tissue — from the joint lining, then brushes them into blood clots to help the knee heal itself.

New research from the University of Leeds shows the treatment increases the number of repair cells in the area by a hundredfold. 

It also found that a conventional procedure for knee damage, called arthroscopy — a keyhole procedure to examine and clear out any damage — may actually clear out the cells it needs for repair.

‘These joint procedures are inadvertently washing out the resident stem cells,’ explains Dennis McGonagle, a professor of investigative rheumatology at the university, who has led development of the new treatment. ‘They may be sluicing away the very cells that are capable of repairing knees.’

In a healthy joint, cartilage provides a low-friction surface to allow smooth joint movement. But wear and tear and knocks take their toll, and cartilage can become damaged, leaving bone rubbing on bone, causing the pain and loss of movement associated with osteoarthritis.

In severe cases, a total knee replacement is needed, but in more common mild to moderate cases, a range of other approaches are used, including painkillers, knee braces and arthroscopic procedures.

One technique, microfracture, involves using a drill or pick to make small holes in the bone surfaces inside the joint to encourage new cartilage to grow. The stem cells that are released are thought to be trapped in blood clots, contributing to the repair of the cartilage.

But one of the problems is that it had been thought the number of repair stem cells in the knee is low. The Leeds team discovered that the synovial fluid, an egg white-like lubricant within joints, contains stem cells.

Further research also showed that this fluid stopped stem cells sticking to injured cartilage and also that surgical procedures inadvertently wash away these cells. A device was then developed to release lots more stem cells from the joint lining.

Following lab tests this is now being tested on patients with knee arthritis. The new procedure on trial involves creating a microfracture, which results in a clot — and then stem cells are collected by raking them into the clot with the specially designed device inserted through a small hole made in the joint.

In a recent report in The American Journal of Sports Medicine, the Leeds researchers found that the brush resulted in a 105-fold increase in the number of stem cells.

Professor McGonagle says: ‘We believe the new approach will greatly increase the reparative capacity of the joint by boosting stem cell numbers and keeping them within the joint after surgery.’

The new trial will involve 20 patients undergoing microfracture — half will also have the stem cell treatment.

Roger Hackney, a consultant orthopaedic surgeon at the Spire and Nuffield hospitals in Leeds, says: ‘Knowing whether increasing the numbers of stem cells available improves outcomes using a device such as this adds another piece of the jigsaw, but we are a long way off no longer needing surgery for osteoarthritis.’