OrthoNet

Evaluation of the Failed or Painful Total Knee Replacement

History
- original diagnosis
- WWF CART
- post-op problems, especially infection
- any sounds of grating

Physical
- gait
- 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
- don�t 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:

Sepsis
Mechanical Failure
- loosening secondary to malalignment, polyethylene wear, or instability
- extensor mechanism problems secondary to instability, fracture, delamination, AVN, poly wear
- implant failure
Malalignment
Instability
Stiffness