Total Knee Replacement (TKR) Procedure
Total knee replacement is a surgical procedure that replaces a damaged knee joint with an artificial prosthesis, primarily performed to treat severe osteoarthritis when conservative treatments have failed 1.
Surgical Indications
TKR should only be performed when patients meet all three criteria: radiological evidence of moderate-to-severe joint damage, moderate-to-severe persistent pain unrelieved by nonsurgical management, and clinically significant functional limitation diminishing quality of life 1.
Patient Selection Requirements
- Young patients must have documented radiographic evidence of moderate-to-severe osteoarthritis with joint damage AND must have completed at least one trial of nonoperative therapy including physical therapy, NSAIDs, and/or intraarticular injections without improvement 2.
- Most patients undergoing TKR are between 55 and 84 years old, with more women than men receiving the procedure 1.
- Primary indication is pain, followed by functional limitation that substantially affects daily activities 1.
Surgical Technique
Prosthesis Types
The procedure involves three main prosthesis options 1:
- Non-constrained prostheses: Rely on the patient's intact ligaments and muscles for stability
- Semi-constrained prostheses: Provide partial stability, not entirely dependent on patient's soft tissues
- Constrained prostheses: Used when patient's ligaments and muscles cannot provide adequate stability
Components Replaced
The surgery replaces both the medial and lateral femorotibial joints and the patellofemoral joint 3.
Technical Considerations
Strong evidence supports using either all-polyethylene or modular tibial components with no difference in outcomes 2.
Patellar resurfacing shows no difference in pain or function compared to non-resurfacing, though it may decrease cumulative revision surgeries after 5 years 2.
Intraoperative navigation should NOT be used in TKA because there is no difference in outcomes or complications 2.
Perioperative Management
Prophylaxis
- Deep venous thrombosis prevention with heparin prophylaxis and/or support stockings 1
- Antibiotics administered for 24 hours after surgery to minimize infection risk 1
Rehabilitation Protocol
Rehabilitation must be started on the day of TKA to reduce hospital length of stay 2.
A supervised exercise program during the first 2 months after TKA is strongly recommended to improve physical function 2.
Continuous passive motion after knee arthroplasty should NOT be used as it does not improve outcomes 2.
Early mobilization in the days and weeks following surgery prevents stiffness, a common complication 1.
Postoperative Imaging Follow-up
Plain radiographs (anteroposterior, lateral, and axial views with weight-bearing when possible) are the primary imaging modality for evaluating TKR patients 2, 4.
For asymptomatic TKR follow-up, knee radiographs should be obtained with a rating of 9/9 for appropriateness 4.
Annual weight-bearing radiographs are recommended for detecting subclinical prosthesis wear that could lead to mechanical symptoms 5.
Full-length hip-to-ankle weight-bearing views are used specifically for alignment assessment 2.
Common Complications and Failure Modes
The most common failure mechanisms in order of frequency are 2, 4:
- Loosening (39.9%)
- Infection (27.4%)
- Instability (7.5%)
- Periprosthetic fracture (4.7%)
- Arthrofibrosis (4.5%)
Infection is the most common reason for early revision (<2 years after initial TKA), while aseptic loosening is the most common reason for late revision 2, 4.
Critical Pitfall
In cases of unexplained pain, reoperation is unwise and frequently associated with suboptimal results 2, 4. Identifying the specific cause of pain before considering revision surgery is critically important 2.
Expected Outcomes
Patients who undergo TKR surgery for osteoarthritis have substantial improvements in pain reduction and functional improvement, with effect sizes showing at least 20% improvement in outcome scores 1.
Patient satisfaction rates range from 75% to 89% 4.
Long-term TKR failure rates are generally <1% per year 4, 6.
Revision rates range from 0% to 13% in studies with at least 5 years of follow-up 1.