Understanding Knee Replacement

Aug 12, 2021 | Articles

The articulation between the thigh bone and the lower leg is known as the tibiofemoral joint. In a healthy subject, the joint acts as a hinge allowing up to 180 degrees of flexion but minimal rotation. The natural ageing process and damage due to injury or disease frequently give rise to swelling and pain in the joint, which, over time, may lead to impaired mobility. When pain killers fail, there is a surgical solution.

Since the technique first became feasible in the late ’60s, the demand for tibiofemoral arthroplasty or knee replacement has continued to grow. The procedure is now widely viewed as among the most successful of all orthopaedic surgical interventions. So, what conditions most often lead to a need for this form of surgery?

Indications for Knee Arthroplasty

Pain and swelling in this joint may occur for several reasons. Sports injuries are a common cause among younger subjects and, unless bone damage is severe, will often respond to physiotherapy and analgaesics. Several disease processes may also progress to the point where a knee replacement may be the only feasible therapeutic option. The most common of these is osteoarthritis.

Although occurring predominately in subjects aged 65 and over, the incidence among younger people has been increasing. The condition results from erosion of the protective layer of smooth cartilage that overlays the articulating surfaces of the femur, tibia or both. The exposed bone surfaces are then exposed to frictional forces that cause the chipping and cracking responsible for pain when the joint is bent. Rheumatoid arthritis, gout and abnormal bone growth may also necessitate a knee replacement.

While there remains some controversy regarding the rising incidence of osteoarthritis in younger people, there is a growing consensus that it may be due to the parallel growth in obesity. However, surgeons only recommend arthroplasty regardless of age when painkillers and steroid therapy no longer provide relief. The symptoms could compromise a patient’s mobility, quality of life, and mental health.

The Procedure Explained

Depending on the extent of the damage, a surgeon may choose to perform either a partial or total knee replacement. The procedure involves removing the damaged bone and cartilage from the femur, tibia or both and attaching metal implants to the exposed surfaces. A plastic spacer is placed between the two, acting like cartilage to ensure the new joint moves smoothly.

While open surgery to fully expose the joint was once the sole option, some surgeons now perform a minimally invasive procedure, using two or three small incisions. More significantly, many of those who have gained a new lease of life following a knee replacement must thank the orthopaedic team at the Wilgers Life hospital in Pretoria.