Total Knee Arthroplasty (TKA) is the most commonly performed joint replacement surgery in the United States (1,2) with an estimated 4 million patients walking around with a replaced knee.
Total Knee Arthroplasty (TKA) is the most commonly performed joint replacement surgery in the United States (1,2) with an estimated 4 million patients walking around with a replaced knee. Failure rates of TKAs can be secondary to prosthetic loosening, infection, instability, periprosthetic fracture, arthrofibrosis, polyethylene wear, malalignment, extensor mechanism deficiency, patellar subluxation/fracture, among other less common causes. Detecting these complications requires a clinical acumen, knowing what you are looking for, and a broad understanding of the capabilities and limitations of the various imaging modalities available.
A recent review article on the appropriateness of imaging published in the journal of the American College of Radiology (ACR) looked at over 168 publications to determine the appropriateness of a variety of post-TKA imaging. In this review article, the authors looked at 12 common clinical scenarios of a post op TKA patient with the imaging recommendations rated by appropriateness by the American College of Radiology. Asymptomatic Knee Rating = American college of radiology appropriateness scale: 1,2,3 usually not appropriate; 4,5,6 may be appropriate; 7,8,9 usually appropriate.
Several studies indicate that radiographs are not needed until first outpatient follow up appointment unless the procedure was complicated. On outpatient visit, some providers recommend getting a baseline hip to ankle x-ray which may be better in calculating tibiofemoral angle to assess coronal plane alignment of the joint, but other studies show a standard AP is a valid alternative. An AP image may prove to be beneficial in future as a comparison if malalignment becomes an issue.
It is generally recommended and accepted that every 1 to 2 years, the patient should get an x-ray of their knee in an asymptomatic patient. However, there is no concrete guidelines or recommendations. Pain from prosthesis Rating = American college of radiology appropriateness scale: 1,2,3 usually not appropriate; 4,5,6 may be appropriate; 7,8,9 usually appropriate.
Patients can present with pain and symptoms related to the wear and degeneration of the polyethylene articular surface. This is best assessed with 3 view radiographs which can show joint space narrowing, varus or valgus deformity, or patellar tilt. Fluoroscopy can allow the provider to evaluate the joint under varus and valgus stress which can help improve the evaluation of polyethylene thickness.
If you are experiencing symptoms that may be related to imaging after a total knee arthroplasty, it is important to see a sports medicine physician. Early evaluation and treatment typically lead to better outcomes. Do not ignore pain or symptoms that are limiting your activity.
*This article is for educational purposes only and does not substitute for professional medical advice. Always consult a qualified healthcare provider.*
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