Total Knee Arthroplasty (TKA): Procedure, Candidates, and Recovery

What is TKA medical?

TKA, medically known as Total Knee Arthroplasty, is a surgical procedure to replace a severely damaged or diseased knee joint with artificial components, aiming to alleviate pain and restore function.

Understanding Total Knee Arthroplasty (TKA)

Total Knee Arthroplasty (TKA), often referred to simply as total knee replacement, is a common orthopedic surgical procedure performed to resurface a knee damaged by arthritis or injury. The primary goal of TKA is to relieve severe pain and disability, allowing individuals to resume more active and functional lives. This procedure involves replacing the diseased bone and cartilage with prosthetic components designed to mimic the natural movement of a healthy knee joint.

Anatomy of the Knee and Why TKA is Needed

To understand TKA, it's crucial to grasp the basic anatomy of the knee joint and the conditions that necessitate such a significant intervention.

• Key Components of the Knee Joint: The knee is a hinge joint formed by the articulation of three bones:
  • Femur: The thigh bone.
  • Tibia: The shin bone.
  • Patella: The kneecap. These bones are covered at their ends by smooth articular cartilage, which allows for frictionless movement. Ligaments provide stability, and muscles facilitate movement.
• Common Conditions Leading to TKA: The most frequent reason for TKA is severe arthritis, which causes the protective articular cartilage to wear away, leading to bone-on-bone friction, pain, swelling, and stiffness.
  • Osteoarthritis (OA): The most common form, often age-related, where the cartilage progressively degenerates.
  • Rheumatoid Arthritis (RA): An autoimmune disease that causes chronic inflammation of the joint lining, leading to cartilage and bone damage.
  • Post-traumatic Arthritis: Arthritis that develops after a severe knee injury, such as a fracture or ligament tear.

The TKA Surgical Procedure

The TKA procedure typically involves several key steps:

• Resurfacing the Joint: The surgeon carefully removes the damaged cartilage and a small amount of underlying bone from the ends of the femur and tibia, and often from the back of the patella.
• Implant Components: Artificial components, known as prostheses, are then precisely fitted to the prepared bone surfaces. These typically include:
  • Femoral Component: A metal cap that covers the end of the thigh bone.
  • Tibial Component: A flat metal plate with a durable plastic (polyethylene) insert that replaces the top surface of the shin bone. The plastic insert acts as the new cartilage.
  • Patellar Component: A plastic button that may be placed on the back of the kneecap if its surface is also damaged.
• Materials Used: The implants are made from biocompatible materials, typically durable metal alloys (like cobalt-chromium or titanium) and high-grade plastics (ultra-high molecular weight polyethylene). These materials are chosen for their strength, wear resistance, and ability to integrate with the body.

Who is a Candidate for TKA?

TKA is generally considered when conservative, non-surgical treatments have failed to provide adequate relief. Ideal candidates typically meet several criteria:

• Severe Pain and Disability: Persistent knee pain that significantly limits daily activities such as walking, climbing stairs, getting in and out of chairs, and interferes with sleep.
• Failure of Conservative Treatments: The individual has tried and not found sufficient relief from non-surgical options like physical therapy, medication (anti-inflammatories, pain relievers), corticosteroid injections, or bracing.
• Imaging Evidence: X-rays clearly show significant joint damage, such as severe cartilage loss and bone-on-bone contact.
• Age and Activity Level Considerations: While there's no strict age limit, TKA is most commonly performed on individuals between 50 and 80 years old. However, it can be successful at any age if the patient's health and functional needs warrant it.

The Rehabilitation Process: A Kinesiology Perspective

Rehabilitation is a critical component of a successful TKA outcome, often beginning within hours of surgery. A kinesiologist or physical therapist plays a central role in guiding the patient through a structured recovery program.

• Immediate Post-Operative Phase: Focuses on pain management, preventing complications (like blood clots), and initiating early mobility. Patients are encouraged to begin gentle ankle pumps and knee bending exercises.
• Early Rehabilitation Goals: Within the first few weeks, the emphasis is on regaining knee range of motion (flexion and extension) and activating the quadriceps muscles, which are often inhibited by pain and swelling. Gait training with assistive devices (walker, crutches) is initiated.
• Progressive Strengthening and Functional Training: As pain subsides and mobility improves, exercises progress to include strengthening of the quadriceps, hamstrings, glutes, and calf muscles. Functional activities such as stair climbing, balance training, and proprioceptive exercises become central. The goal is to improve stability and confidence in movement.
• Long-Term Considerations: Adherence to a home exercise program is crucial for maintaining strength and flexibility. Patients are typically advised to avoid high-impact activities (e.g., running, jumping) to protect the implant, but can often return to walking, swimming, cycling, and golf.

Potential Risks and Complications

While TKA is a highly successful procedure, like any surgery, it carries potential risks:

• Infection: Though rare, infection can occur at the surgical site or around the prosthesis, sometimes requiring further surgery.
• Blood Clots: Clots can form in the leg veins (DVT) and potentially travel to the lungs (pulmonary embolism). Prophylactic measures are taken to prevent this.
• Implant Loosening or Wear: Over time, the artificial components can loosen from the bone or the plastic insert can wear out, potentially requiring revision surgery.
• Nerve or Blood Vessel Damage: Rare, but can occur during the procedure.
• Stiffness or Instability: Some patients may experience persistent stiffness or a feeling of instability in the knee.

Expected Outcomes and Longevity

The vast majority of individuals undergoing TKA experience significant improvements in pain relief and function.

• Pain Relief and Improved Function: Most patients report dramatic reduction in pain and are able to resume many daily activities with greater ease and comfort.
• Return to Activities: While high-impact activities are generally discouraged, patients can typically return to low-impact recreational activities such as walking, swimming, cycling, and golf.
• Implant Lifespan: Modern knee replacements are highly durable, with over 90% still functioning well 15-20 years after surgery. The longevity of the implant depends on factors such as patient activity level, weight, and adherence to post-operative guidelines.