[A diagnostic algorithm for painful total knee replacement].
Total knee arthroplasty (TKA) is one of the most common procedures in orthopedic surgery and clinical success can be characterized by the revision rate and improvement of function, as well as the patients' satisfaction and pain. Despite the clinical success of primary TKA with 10-year survival rates as high as 95 %, about 20 % of the patients after TKA are not completely satisfied with their outcomes for several reasons. Obvious causes of failure might be identified with clinical examinations and standard radiographs only, whereas the unexplained painful TKA still remains a challenge for the surgeon. Failure can be classified into extra- and intraarticular disorders, the latter being divided into biological and mechanical origins. The onset of the pain after the operation and the differentiation between pain in motion and at rest are helpful to distinguish between mechanical and non-mechanical problems. An infection should be the first diagnosis to be ruled out in a painful TKA. It is generally accepted that a clear understanding of the failure mechanism in each case is required prior to considering revision surgery.


METHODS
In this review a practical diagnostic algorithm is described for failure analysis in more detail. The evaluation of a painful TKA includes a detailed history with an extended analysis of the type of pain, thorough clinical examination including spine, hip and ankle, radiographic and laboratory analysis, as well as invasive examinations like joint aspiration and biopsies.


CONCLUSIONS
This diagnostic algorithm offers an important tool for a sufficient failure analysis in almost all patients with painful TKA.
Orthopädische Klinik Markgröningen.
B
B
Fink
Universitätsklinik für Orthopädie, Medizinische Universität Wien.
R
R
Lass
D000465:Algorithms; D018771:Arthralgia / Q000175:diagnosis* / Q000209:etiology*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D019544:Equipment Failure Analysis / Q000379:methods; D006801:Humans; D010147:Pain Measurement / Q000379:methods*; D011475:Prosthesis Failure; D016459:Prosthesis-Related Infections / Q000175:diagnosis* / Q000209:etiology*