For Professor S P Chow, Chair of Orthopaedics and Traumatology at The University of Hong Kong, optimising the design and development of artificial finger joints is almost a personal project and it spans more than 30 years.
He first became interested in the potential of a prosthetic device for fingers during the 1970s while studying under the then master of hand surgery, Professor Alfred Swanson, in Michigan.
While artificial joint prostheses were successfully used in hip and knee joint replacements, no-one was achieving the same level of results with finger joint replacements.
The difficulty came in trying to reproduce the complex anatomical structure of finger joints. "The small size of the joint components presented long term clinical problems and made surgical procedures difficult," says Professor Chow.
Rheumatoid arthritis, osteoarthritis and post traumatic arthritis are the key causes of finger deformity, resulting in pain, joint instability and deformity, and a loss of hand function.
Professor Chow came up with a design for one-piece and two piece finger joint implants that ensured a locking ability required along the length of a finger while retaining shape, size and flexibility. The Industrial Support Centre, in HKU's Faculty of Engineering, identified suitable materials and manufacturing processes to produce the two joints artificially.
A prototype bronze model was prepared and, once this was judged workable, engineering and biological tests began.
The new prosthetic device is capable of providing pain relief, increased movement range, enhanced fixation and intrinsic joint stability. Professor Chow says it is also a very durable device.