A Total Knee Replacement (also called Total Knee Arthroplasty, Full knee replacement) is a surgical procedure designed to replace a severely diseased knee joint with an artificial knee joint.

The knee is a rotating hinge joint involving the femur (thigh bone), tibia (shin bone) and patella (knee cap). In a total knee replacement, the ends of the femur and tibia, and sometimes the patella, are surgically removed and replaced with an artificial joint known as a prosthesis.

Total Knee replacement surgery is usually performed when advanced arthritis causes pain and stiffness of the knee joint, seriously restricting movement and quality of life. Total Knee replacement is generally recommended only when other treatments such as medication, physiotherapy and exercise are no longer effective.

Knee replacement may also be necessary to treat knee damage resulting from conditions including rheumatoid arthritis, haemophilia, gout, bone death or bone growth disorders.

A total knee replacement is designed to help with pain and restore the bending movement of the knee.

Computer navigated total knee replacement

During a joint replacement procedure, it is important that everything is aligned properly. Accurate alignment of the knee components is critical to the overall function of your new joint and also plays a role in helping your joint feel healthy again, and helping the joint replacement to potentially last longer. This technique is often used when normal anatomy, alignment and reference points are lost e.g. after a serious injury and leg bones have not healed correctly. I describe this as using the technology to allow me to fit the appropriate prosthesis to the patient rather than the other way around and make the patient fit the prosthesis.

 

Computer-assisted technology has made it possible to navigate joint replacement procedures with a level of accuracy so precise it may improve the results of your surgery.

Computer Navigation technology uses special tracking devices, providing a comprehensive understanding of your joint mechanics in the operating room (OR). Armed with this information, adjustments within a fraction of a degree are made, helping to ensure your new joint has the stability and range of motion needed for a successful replacement. Specifically, the technology uses the latest advancements in science and computer engineering to make the procedure more accurate than joint surgery without it.

As an instrument is moved within your joint, special infrared trackers calculate its position and wireless instruments instantaneously transfer the data to a computer in the OR. This information is then displayed on a monitor as an interactive model of the anatomy or “blueprint” that supplies all the angles, lines and measurements of your unique anatomy. Your diseased bone is then replaced with new, artificial joint components often called prostheses or implants. Joint implants are engineered to replicate a normal, healthy joint.

Robotic Total Knee Replacement

Robotic surgery is a natural evolution of computer navigated total knee replacement as described above. The surgeon determines alignment, anatomy and soft tissue balancing both prior and during the operation and virtually performs the total knee replacement with the computer software. Again the technology to allows me to fit the appropriate prosthesis to the patient rather than the other way around and make the patient fit the prosthesis. Then with computer assistance, the surgeon guides the programmed robotic arm in resurfacing the damaged part of the knee.

There are several types of robots that vary in the way they collaborate with the surgeon from the robot being the saw or burr which the surgeon advances (MAKO – Stryker), robot holds the cutting guides (ROSA – Zimmer) to the saw being “robotically navigated” while the surgeon holds it (Smith and Nephew – Navio).

Depending on patient suitability my preference is MAKO for partial knee replacement as its ability to burr bone rather than a saw blade allows a truly anatomical resurfacing with replacement of the deficient bone and cartilage and ROSA for total knee replacement. These technologies are new and are in continual research and development as with any other.

Patient Specific Instrumentation

Patient specific instruments ensure that the end surgical result matches preoperative planning. 3D modelling from MRI captures true patient anatomy. Again this technology allows me to fit the prosthesis to the patient rather than the other way around and make the patient fit the prosthesis. This is planned prior to the operation.

Custom guides are designed for each patient from their 3D MRI modelling. This enables the surgeon to assess and take into account each patients unique differences (e.g. height, femoral & tibial alignment and rotation ) prior to surgery to ensure best results.

Intraoperative Pressure Sensors

Sensor-Assisted Total Knee Replacement. Verasense, a wireless orthopaedic sensor device can be used during the  operation that enables evidence-based decisions on soft tissue balance and implant position.

It essentially validates the positioning of the trial total knee replacement before definitive insertion regardless of the techniques and technology used.

Decreasing pain and improving recovery time

Inflammation and oedema (swelling) occurs after all types of surgery. Generally the longer the surgery and the more invasive it is (e.g bone cuts in a total knee replacement versus a soft tissue procedure such as a hernia repair) the greater the inflammation and oedema.

Inflammation is a crucial process by which the body heals itself. However, a common cause for delayed recovery and increased pain in a total knee replacement is when there is too much swelling and inflammation. This is combatted in multifactorial ways both during the operation (e.g. local infiltrative analgesia combined with a spinal anaesthetic block)  and afterwards on the ward.

Routinely used on the ward is ice and compression with a tubigrip stocking (surgical sock). A more effective technique is the use of a compression and cooling brace which can be manually controlled to the desired pressure and temperature. This is regularly used by professionally athletes to recover more quickly from surgery. Please contact my staff for further information on this prior to surgery

Managing Arthritic Pain and relationship to XR changes

Cartilage degeneration, although fundamental to the progression of osteoarthritis, is not the site of origin of pain. Peripheral nerves generally follow the path of blood vessels, and cartilage contains no nerves or blood vessels. Pain may be from the joint capsule , synovium (lining of capsule which produces fluid) , ligaments or bone as well as in the muscles and soft tissues, which surround and move the joint.

Plane radiographs show the effect of degeneration of joint cartilage as narrowing of the space between the surfaces of the articular bone (usually called the “joint space” or, more accurately, the “cartilage space”). However, it is possible to have considerable pain despite a normal-looking cartilage space, or pain can be mild despite marked narrowing.

Common radiographic changes often seen and reported in osteoarthritis are thickening of the subchondral bone (sclerosis) and formation of bone spurs (osteophytes) often do not correlate with the presence or the severity of pain. It is important to optimise a conservative management program before considering surgery.

Optimising Conservative Management

Before considering surgery it is important to have exhausted and optimised all non-surgical interventions as well as improving general health. Your physiotherapist and GP can help with this.

A good place to start and an excellent source of advice is Musculoskeletal Australia.

The effort and time put into conservative management even if it fails is not lost. This should be considered as “Pre-Rehabilitation” and ensures that on the day of surgery you are as fit and healthy as possible. It ensures recovery as rapid as possible and improves the chances of an excellent outcome.

Weight Loss

If weight is an issue 10% weight loss from diet and exercise can result in a 38% improvement in knee pain and function scores. This should be strongly considered prior to surgery as part of a Pre-Rehabilitation program.

It has been common practise in Australia and Internationally to give patients after total knee repalcement or total hip replacement antibiotics prior to dental treatments to decrease the risk of infection of the joint replacement.

Most antibiotic coverage is not evidence based but rather anecdotal, historical or medico-legally based. The decision to cover with antibiotics needs to be individually assessed relative to both the health of the patient and the dental procedure being performed.

Download pdf of complete requirements for antibiotic prophylaxis.

For more information:

• SOS Clinic