Knee Replacement

Reasons for Knee Replacement:

Knee replacement is typically recommended when other treatments, such as medication, physical therapy, and lifestyle modifications, have failed to provide adequate pain relief and improve function. Common reasons for needing a knee replacement include:

• Osteoarthritis (OA): The most common cause, involving the breakdown of cartilage in the knee joint.
• Rheumatoid Arthritis (RA): An autoimmune disease that causes inflammation and damage to the joint lining.
• Post-Traumatic Arthritis: Arthritis that develops after a knee injury, such as a fracture or ligament damage.
• Avascular Necrosis: Loss of blood supply to the bone, leading to bone death and joint damage.
• Other Conditions: Gout, lupus, and other inflammatory conditions can also cause knee damage.

Who is a Good Candidate for Knee Replacement?

Good candidates for knee replacement typically:

• Experience severe knee pain that limits their daily activities, such as walking, bending, or climbing stairs.
• Have knee stiffness that restricts movement.
• Have not found sufficient pain relief from conservative treatments (medication, physical therapy, injections).
• Have X-ray evidence of significant knee joint damage.
• Are generally healthy enough to undergo surgery.
• Understand the procedure, recovery process, and potential risks.
• Have realistic expectations about the outcome of the surgery.

Types of Knee Replacement:

The type of knee replacement performed depends on the extent of the damage and the specific needs of the patient:

1. Total Knee Replacement (TKR):
   • Description: The most common type, where the entire knee joint (the ends of the femur (thigh bone), tibia (shin bone), and sometimes the patella (kneecap)) is replaced with artificial components.
   • Components:
     • Femoral Component: A metal (typically cobalt-chromium or titanium) component that resurfaces the end of the femur.
     • Tibial Component: A metal tray that is placed on the top of the tibia, with a plastic (polyethylene) insert that serves as the new cartilage surface.
     • Patellar Component (optional): A plastic (polyethylene) button is sometimes used to resurface the back of the patella.
   • Procedure: The surgeon makes an incision, removes damaged cartilage and bone, prepares the bone surfaces to fit the implants, and attaches the artificial components.
2. Partial Knee Replacement (PKR) (Unicompartmental Knee Replacement):
   • Description: Only one side (compartment) of the knee joint is replaced. This is an option if only a portion of the knee is damaged, typically due to osteoarthritis.
   • Advantages: Less invasive than TKR, with a shorter recovery time. More natural feel.
   • Disadvantages: Not suitable for all patients. Requires intact ligaments and healthy cartilage in the other compartments of the knee.
   • Compartments:
     • Medial Compartment PKR: Replaces the inner side of the knee.
     • Lateral Compartment PKR: Replaces the outer side of the knee.
     • Patellofemoral Compartment PKR: Replaces the joint between the kneecap and the femur (patellofemoral joint).
3. Custom Knee Replacement:
   • Description: A customized implant is designed and manufactured specifically for the patient’s unique anatomy. This may be considered in cases of complex deformity or revision surgery.
   • Advantages: Can improve the fit and function of the artificial joint.
   • Disadvantages: More expensive.

The Knee Replacement Procedure:

The general steps involved in a knee replacement procedure:

1. Pre-operative Evaluation:
   • Medical history and physical examination.
   • X-rays and other imaging studies (MRI or CT scan) to assess the knee joint.
   • Blood tests and other tests to evaluate overall health.
   • Patient education about the procedure, risks, and recovery.
2. Anesthesia:
   • Spinal anesthesia (preferred) or general anesthesia may be used.
   • A nerve block may be administered for post-operative pain management.
3. Surgical Incision:
   • An incision is made over the front of the knee. The length of the incision varies.
4. Knee Preparation:
   • The surgeon moves the patella aside (or removes it if necessary).
   • Damaged cartilage and bone are removed from the ends of the femur and tibia.
   • The bone surfaces are prepared to receive the implants.
5. Component Implantation:
   • The femoral component is attached to the end of the femur.
   • The tibial component (metal tray and plastic insert) is attached to the top of the tibia.
   • The patellar component (if used) is attached to the back of the patella.
   • The artificial components are often secured using bone cement or press-fit techniques.
6. Closure:
   • The incision is closed with sutures or staples.
   • A dressing and bandage are applied.
   • A drain may be inserted to remove excess fluid from the surgical site.

Recovery After Knee Replacement:

Recovery is a gradual process and requires dedication to physical therapy.

1. Hospital Stay:
   • Patients typically stay in the hospital for 1-3 days, depending on their progress and the surgeon’s protocol.
2. Pain Management:
   • Pain is controlled with medication (pain relievers, nerve blocks).
   • Ice packs and elevation are used to reduce swelling and pain.
3. Physical Therapy:
   • Essential for regaining strength, range of motion, and function.
   • Exercises are started very soon after surgery (often the same day).
   • The physical therapy program progresses over several weeks and months.
   • Exercises focus on range of motion, strengthening muscles around the knee (quadriceps, hamstrings), and gait training.
4. Weight-Bearing:
   • Weight-bearing restrictions vary depending on the type of surgery and the surgeon’s preference.
   • Patients may use a walker, crutches, or cane for a period of time.
   • Progressive weight-bearing is typically encouraged as tolerated.
5. Home Care:
   • Patients may need assistance at home with activities of daily living, such as dressing, bathing, and meal preparation.
   • A home health nurse or physical therapist may visit to provide care and therapy.
6. Follow-Up Appointments:
   • Regular follow-up appointments with the surgeon are necessary to monitor progress, assess wound healing, and address any concerns.

Potential Risks and Complications of Knee Replacement:

As with any surgery, knee replacement carries risks. Understanding these is important:

• Infection:
  • Infection at the surgical site is a serious complication.
  • May require antibiotic treatment or further surgery.
• Blood Clots:
  • Formation of blood clots in the legs (deep vein thrombosis – DVT) or lungs (pulmonary embolism – PE).
  • Medications (blood thinners) and compression stockings are used to reduce the risk.
• Bleeding:
  • Excessive bleeding during or after surgery.
• Nerve Damage:
  • Damage to nerves, leading to pain, numbness, or weakness.
  • Rare but can be permanent.
• Dislocation:
  • The artificial knee joint can dislocate.
  • Uncommon.
• Loosening or Failure of the Implant:
  • Over time, the artificial joint may loosen or wear out.
  • May require revision surgery (replacement of the artificial joint).
• Fracture:
  • Fracture of the bone during surgery or after.
• Stiffness:
  • Stiffness of the knee joint.
  • Physical therapy is essential to regain and maintain range of motion.
• Allergic Reaction:
  • Allergic reaction to the implant materials or anesthesia.
• Leg Length Discrepancy:
  • A difference in leg length can occur, which can usually be corrected.
• Persistent Pain:
  • Some patients experience persistent pain after surgery.
  • Various factors can contribute to this, and further evaluation may be needed.

Preventative Measures and Long-Term Care:

To maximize the success and longevity of your knee replacement:

• Follow Surgeon’s Instructions: Strictly adhere to all post-operative instructions.
• Physical Therapy: Continue with physical therapy as prescribed.
• Regular Exercise: Maintain a regular exercise program to strengthen muscles and improve overall health.
• Maintain a Healthy Weight: Obesity can put extra stress on the artificial joint.
• Avoid High-Impact Activities: Limit activities that put excessive stress on the knee (running, jumping, etc.).
• Protect the Joint: Take precautions to avoid falls and injuries.
• Report Problems: Report any signs of infection, pain, or other concerns to your surgeon promptly.
• Dental Hygiene: Practice good dental hygiene to reduce the risk of infection.
• Antibiotic Prophylaxis: Discuss with your surgeon the need for antibiotics before any dental work or other procedures that may introduce bacteria into the bloodstream.

Conclusion:

Knee replacement surgery is a highly effective procedure that can significantly improve the quality of life for individuals suffering from severe knee problems. Understanding the process, potential benefits, risks, and adhering to your surgeon’s and physical therapist’s guidance are crucial for a successful outcome. Consult your physician to determine if knee replacement is the right option for you.