Other RANK blockade strategies are being developed, and it is hoivd that one or.more of these agents will permit medical management of periprosthetie osleolvsis.

The evidence is strong that wear particle generation is a significant factor in stimulating periprosthetie inflammation and subsequent bone loss. This may be responsible for aseptic loosening as well as locali/ed osteolysis that may occur even if the prosthesis is well fixed.

Polyethylene damage mechanisms may be delamination, adhesive wear, and abrasive wear. Amount of wear and particles production is affected by stress state of the component and polyethylene wear resistance. The former^ is affected by implant designs, polyethylene thickness, soft tissue stability, component alignment, and weight and activity of the patient. The later is affected by polyethylene manufacture and method of sterilization.

For diagnosis of aseptic loosening of total knee arthroplasty, the identification and interpretation of radiolucent lines are confusing to the point that their analysis is probably meaningless, unless the radiojucency is complete and progressive, a circumstance usually accompanied by ciiuical symptoms.

A normal result on radionucleotides scanning suggests that loosening or infection is an unlikely cause of pain. While the ability of 99mTc-MDP to distinguish loosening from infection is poor.

Clinical,  radiographic,  laboratory,  and joint  aspiratioi correlated to assess the presence or absence of infection.

In revision for aseptic loosening, the cause of failure must be evident. Any special components that may be needed must be ordered. The need for bone graft must also be anticipated.

As a general principle, revision surgery should be performed as soon as failure is diagnosed.