Advances in technology are progressing certain medical procedures and catapulting them into new realms of discovery. With each new breakthrough, patients are presented with more positive outcomes and better opportunities for recovery. Arthroplasty—or knee replacement surgery—is among the procedures which have benefited from technological advancements.
What is it?
Arthroplasty involves replacing the bone of a damaged knee. A patient undergoing knee replacement surgery will be administered general anesthetic before the surgeon begins to remove the worn ends of the bone in the knee. The bone is then replaced with a metal or plastic implant known as a prosthesis, which will be measured to fit before the procedure. There are two main types of knee replacement surgery: total knee replacement (TKR), where both sides of the joint are replaced; and partial knee replacement (PKR), where only one side of the knee is replaced during a smaller operation. TKR is an invasive procedure that comes with both risks and benefits; serious consideration—and thorough research—is advised before undergoing the operation.
Recovery time varies from patient to patient. When ready to leave the hospital, patients are usually given crutches and a course of physiotherapy to strengthen the knee.
When is it necessary?
Knee replacement is necessary when the joint has been damaged to the extent that movement or everyday activity is seriously impaired. The surgery is offered as a last resort if other methods such as steroids and physiotherapy have been unsuccessful. Patients most in need of knee replacement surgery are those who suffer from osteoarthritis. Other common causes for knee damage include rheumatoid arthritis, gout, haemophilia, knee injury and avascular necrosis.
One previous technique for knee replacement surgery involved the positioning of a rod along the femur; depending on where the rod sat was where the first incision would be made. This was a risky practice: the rod would often displace the bone marrow and interrupt the veins in the femur. As the femoral bone is bowed rather than straight, this method was also found to be quite inaccurate.
Advancements in technique and equipment have created options that are more effective yet less invasive for arthroplasty patients. Experienced practitioners are beginning to offer the option of creating 3D models of the knee prior to the surgery using CT scan data to fit the specifics of the patient. A custom-made implant is then designed from these models. This is intended to reduce the chance of an ill-fitting joint and the need for further surgery.
In April this year, experts at Duke University in North Carolina had a breakthrough whilst testing 3D-printing techniques to assist with knee replacement surgery. They found that they could create printable synthetic cartilage that could be perfectly shaped to fit a knee joint.
Human knees have a thin fibrous cartilage between the surfaces of the joints called menisci—this cushions connected joints when we walk or move. The scientists at the North Carolina university have been the first to create a new hydrogel-based cartilage, which matches that of the body in strength and elasticity, whilst also being 3D-printable and stable. Not only does this new technology fit perfectly, but it also supports the growth of new cells to encourage healing around the site of injury. The cartilage was made printable by mixing two types of hydrogel together with a special kind of clay—an innovative idea that had not yet been tried before. This research was published in the journal of ACS Biomaterials Science and Engineering.
Dr Benjamin Wiley, associate professor of chemistry at Duke University, commented: ‘We’ve made it very easy now for anyone to print something that is pretty close in its mechanical properties to cartilage, in a relatively simple and inexpensive process.’
Alternative surgeries to knee replacement include osteotomy—an open operation whereby the surgeon cuts the shinbone and realigns it so that weight is distributed away from the damaged part of the knee—and mosaicplasty. Mosaicplasty is a keyhole operation that involves transferring plugs of hard cartilage and bone from another part of the knee to repair the damage.
If you are suffering from knee joint discomfort, consult your doctor for advice on the best course of action.