Water cuts through bones

Water jets at various pressures drilled into a human heel bone. Higher-pressure jets tend to make smaller holes. (Photo: Steven den Dunnen)

High-pressure water jets might be just the tools orthopaedic surgeons need. Biomechanical engineers have started working on their development.

Some things have to get worse before they get better. Take for instance local injuries to knee cartilage, which are treated by removing the damaged tissue, followed by hammering a series of 3-millimetre holes into the bone’s head. This treatment, devised by Dr Richard Steadman in 1981, is based on the healing properties of the ensuing blood and bone marrow cells, which form a secondary cartilage layer within about a week’s time. The trouble though is that hammering holes is not a very precise procedure.

Enter the Healing Water project, a STW-sponsored programme at TU Delft and the Amsterdam Medical Centre (AMC). The project aims to develop a bone-drilling device based on multiple water jets operating at 300 plus bar. PhD student, Steven den Dunnen, has performed preliminary tests that clearly show the piercing power of the jets (and the surprisingly big backsplash). He has worked on the bones of goats, sheeps, pigs and humans, finding that goat bones are about as fragile as human bones. Moreover, there is a large variety among individuals regarding bone hardness, which depends on age, sex, health and medications. Den Dunnen’s PhD supervisor, Dr Gabrielle Tuijthof (Mechanical, Maritime and Materials Engineering), explains that further research during the next three years should optimise control over the water jet technique.

Meanwhile, medical researcher Aimee Kok MD, of AMC, will study the medical aspects of the Steadman therapy, advising on the optimal depth, configuration and diameters of the holes.
Assuming the Healing Water project lives up to expectations, Tuijthof sees further opportunities for using water jets in orthopaedics. In time, water jets could replace all orthopaedic saws and drills in the operation theatre, offering a fast, clean and controllable technology. But don’t forget to take cover from the backsplash.