Evaluation of the Failed or Painful Total Knee Replacement
– original diagnosis
– WWF CART
– post-op problems, especially infection
– any sounds of grating
– wound – what kind; is there signs of infection
– the extensor mechanism is KEY – a common source of failure. Is it intact? What is the patellar tracking like? Is there an extensor lag? What is the ROM actively and passively
– the ligaments – in full extension, 30 and 90 degrees of flexion – is there ligamentous laxity with varus/valgus malalignment
– the alignment – varus/valgus
– donï¿½t forget to examine the hip, spine, foot/ankle
Xrays – standing AP, lateral, notch, skyline
– component shift or fracture
– complete radiolucency of 2 mm around implant is significant for loosening – the x-ray technique can easily obscure this though!
– evaluate the patella very closely – is there enough bone left? What was the thickness of resection? Is it aligned? Is there patella alta or baha?
Rule out Sepsis!
– CBC, ESR, CRP, and aspiration – do not hesitate to aspirate knees. The hip literature and algorithm is not applicable to knees.
Consider diagnostic marcaine block if confused about source of pain
Consider the Diagnosis:
– loosening secondary to malalignment, polyethylene wear, or instability
– extensor mechanism problems secondary to instability, fracture, delamination, AVN, poly wear
– implant failure