Instability and infections are well-known causes of total knee arthroplasty (TKA) failure. Under-rehabilitation is another less understood cause.
“We see a fair number of patients who are dissatisfied with their outcome who don’t have anything wrong with the knee replacement but are under-rehabilitated,” says Rodney Benner, MD, orthopedic surgeon at Shelbourne Knee Center. These patients continue to have pain, stiffness and weakness beyond the typical recovery period. They’re dissatisfied because the knee doesn’t function as well as they would like it to.
Whatever the cause of the failed TKA, expert workup and treatment often can improve the outcome.
Workup for Failed TKA
The workup for a failed TKA at Shelbourne Knee Center focuses on determining the cause:
- Infection
- Instability
- Poor knee function
Instability can be due to improper balancing of the ligaments or mechanical complications such as mal-alignment of prosthetic components or separation of prosthetic components and bone.
Tests for infection, X-rays, and a knee exam comprise the workup. Since infection after TKA presents subtly, Dr. Benner always orders blood tests (C-reactive protein and the sedimentation rate) and synovial fluid analysis to evaluate for infection. X-rays, taken on site at Shelbourne Knee Center, enable him to identify any signs of implant loosening or loose alignment. He also performs a knee exam to evaluate knee stability and whether the ligaments are balanced.
If the results of the workup are negative, physical therapy is usually the next step. If Dr. Benner finds infection or instability, revision TKA is necessary.
Physical Therapy for Failed TKA
Shelbourne Knee Center’s physical therapy protocol for both TKA and failed TKA focuses on restoring range of motion first (extension followed by flexion) and then strength.
Each patient works with one physical therapist, who provides guidance through the entire process. Most pre-op rehab is done in the patient’s home, with periodic visits to Shelbourne Knee Center.
Through physical therapy at Shelbourne Knee Center, patients often gain the knee function they expected after their TKA. “We’ve even had a few patients who were scheduled for revision surgery who improved enough to cancel surgery,” says Dr. Benner.
More Testing
If a patient doesn’t make progress in physical therapy, Dr. Benner orders more tests, such as a CT scan to look for poor rotation of components or a bone scan to identify subtle loosening that doesn’t show on X-rays. He also evaluates the patient for extrinsic causes of knee pain, such as hip arthritis, other hip problems or back problems.
Revision Surgery for Failed TKA
When revision TKA is indicated, Dr. Benner has the extensive experience that’s required for a good outcome in this technically-challenging procedure. He regularly performs revision TKA, which requires meticulous preoperative planning and the use of specialized tools and patience during the procedure to preserve as much of the bone as possible.
Dr. Benner completed a fellowship in knee surgery, adult reconstruction and sports medicine at The Insall Scott Kelly Institute. He is also co-author of “Tibial Tubercle Osteotomy in Revision Total Knee Arthroplasty,” published in Techniques in Revision Hip and Knee Arthroplasty (Giles R. Scuderi MD, author, 1st edition, 2014).
Shelbourne Knee Center’s process for primary and revision TKAs includes precautions and interventions to minimize pain and swelling and facilitate healing. These include:
- A Continuous Passive Motion machine that keeps the knee elevated and continuously moving at a small degree of flexion
- A compression stocking
- A knee Cyro-Cuff, to provide cold and compression. K. Donald Shelbourne, MD, orthopedic surgeon, invented the knee Cyro-Cuff
- Lying down with the leg elevated for the first week after surgery
- A post-op knee TKA rehab program that focuses on restoring range of motion before strengthening
For more information about failed TKA, call 888-FIX-KNEE.