Painful Total Knee Arthroplasty
Frequently, patients who have had a TKA, will return to their physician because they are experiencing pain. There are numerous complaints patients may have: including aching pain, instability, catching, stiffness, fatigue, and even wound drainage. The causes of these complaints can be numerous and are often multifactorial. The appropriate workup involves a systematic approach in developing the correct diagnosis. With the rates of primary TKA on the rise nationally, the need for revision surgery is expected to mirror this trend.
What causes TKA failure?
The causes for failure of a TKA can be broken down into 2 broad categories, intrinsic and extrinsic.
- Polyethylene wear
- Implant fracture
- Arthrofibrosis (stiffness)
- Soft-tissue impingement
- Component overhang
- Extensor mechanism dysfunction
- Hip pathology
- Lumbar spine
- Complex regional pain syndrome
- Vascular claudication
- Soft-tissue inflammation
- Periprosthetic fractures
How is TKA failure diagnosed?
A careful and thorough history and physical exam are crucial to the development of the correct diagnosis of TKA failure. Questions regarding the timing, quality, severity and duration of a patient's pain, as well as aggravating and alleviating factors, are essential first steps. The history of a patient's pain can be quite valuable to a physician, such as "Has the knee hurt like this ever since the surgery? Was there a pain-free period of several months or even years?" It is also critical to inquire if there was ever a history of prolonged drainage, procedures for infection (i.e., washouts) or antibiotics prescribed.
A thorough physical exam is performed with attention to a patient's gait, limb alignment, surgical incisions, palpation, range of motion, ligamentous stability, patellar tracking and quadriceps strength. Examination of the hip is crucial as hip arthritis can often cause isolated knee pain. A careful exam of the distal pulses and neurologic status can provide invaluable information.
Standard radiographic evaluation incuding weight-bearing radiographs of the knee in the AP, lateral and sunrise views can provide valuable information regarding implant alignment, osteolysis, polyethylene wear, and fractures. If any of these are detected, surgical consultation should be ordered. Advanced imaging with CT scans, MRI and bone scans are rarely required and should be ordered by the treating surgeon if indicated.
The ESR and CRP are the most valuable laboratory values in the workup of possible infection. Multiple studies have shown these studies to have a high sensitivity and specificity in the diagnosis of infection. If these levels are elevated, patients should be referred to a surgeon for evaluation. Patients should NOT take antibiotics as this can significantly delay or even prevent identification of the organism.
When is surgery indicated?
The decision to perform a revision TKA should be determined by the treating surgeon based on a specific set of goals to address during the procedure, (e.g., instability, loosening, infection, etc.). Occasionally, non-operative treatment with bracing and physical therapy may be indicated, but this should be determined by the treating surgeon. The surgeries to treat TKA failure can range from as simple as changing a liner or removing scar tissue to removal of one or all of the parts. Infections require surgical debridement and often staged removal, prolonged antibiotic therapy and eventual reconstruction to final components. Loose components should be removed and the joint rebalanced and reconstructed.
What are the outcomes?
Revision TKA has shown good results in many studies. Some studies have shown 70%-90% survival of the implants at 10 years after revision. However, the risks are higher in many areas including infection, aseptic loosening and instability secondary to a more extensive surgery, bone loss and scar tissue. Unfortunatley, if a clear etiology is not discovered, revision TKA has poor results.
TKA, Revision and CNOS
CNOS has the area's most experienced orthopaedic surgeons in TKA, including Dr. Daniel Nelson. Fellowship-trained in adult reconstruction, Dr. Nelson has additional training and expertise in the evaluation and treatment of revision TKA and revision total hip arthroplasty. He is a graduate of the Sanford School of Medicine at the University of South Dakota.
Dr. Nelson completed his adult reconstruction fellowship at the Southern Joint Replacement Institute/Vanderbilt University in Nashville, TN. He specializes in joint replacement, and general orthopaedics.