In the 1960s, Sir John Charnley performed the first successful hip replacement operation to relieve the symptoms of osteoarthritis. The femoral head of the hip joint was removed and replaced with a socket and ball implant composed of polythene and steel and anchored with acrylic cement.
Aware that the materials used for the moving parts would wear out over time, Charnley would not perform the procedure on younger patients. The debris produced by the bearing can damage the bone and lead to loosening of the implant, leading to the need for the joint replacement to be re-done (revision). For a long time, surgeons tried to reserve hip and knee replacement for older patients, to try and ensure the joint would last the rest of their life.
There have been great advances in material technology over the years. We now have highly cross-linked polyethylene and advanced ceramics, which have greatly reduced the wear rate compared to the materials Charnley had available. This means that we can have more confidence implanting joints in younger patients, in the knowledge that these materials mean the joint has a good chance of lasting in excess of 20 years.
Prior to knee replacement surgery, various materials were inserted into the knee joint to try and reduce arthritis-related pain with disastrous results. In the early 1950s, surgeons tried to insert a simple hinged design by hammering and chiselling a space in the knee joint, again with little success.
In the 1970s the condylar knee prosthesis was developed, which was more anatomically correct and is the starting point for all modern day knee implants, most of which have very similar designs, basically re-lining the joint. Designs and instrumentation have been improved, to better restore the anatomy of the joint and, along with modern materials, this had led to good knee function being achieved, with the joint having a very good chance of lasting in excess of 15 years.
One of the most important advances in hip and knee replacement in the last 10 years have been in peri-operative care. We now have well established enhanced recovery programmes, which mean that patients are able to get home much sooner. There is good data which tells us that the complication rate is reducing as a result of this. Anaesthetic and pain management techniques mean that patients are much more comfortable after their operation and people are often up and about on the day of surgery. Length of stay has reduced to between 2 and 4 days in most cases. All this means that the surgery is safer and people get back to feeling normal much more quickly.
The most recent technological advance id the use of surgical robots to assist with hip and knee replacement. Various surgical robots have been introduced over the last 2 decades, but never really delivered and were abandoned. We now have the MAKO robot, which does deliver improved accuracy in hip and knee replacement and is becoming widely adopted. Further developments in this technology and likely to deliver even more accurate surgery and further improve results