one or both component, when possible, relaxes soil tissues and often avoids a relieving incision in the quadriceps or an osteotomy of the ubial tubercle. This osteotomy, when neccssarx. must detach a long fragment and be separated from the tibia! cut by a bridge of bone. It allows a good exposure but may lead to secondary displacement or nonunion (92).

Ihiten 13. prefer the reliving incision in the quadriceps because it is easy to repair and does not weaken the quadriceps. The V-Y quadriceps turndown devascularises the patella and weaken the quadriceps (92).

>^i0>

A debridcment of the"supra- and parapatellar regions should be done routinely. Failed knees often produce considerable debris of polyethylene, polymethylmethacrylate, and bone fragments -that can become iriooipuiaied iiitc-th-e syncvium (93).

3 -Implant removal :

When operative inspection reveals granulation tissue, necrotic tissue, or other evidence of infection, the components should be removed, a thorough debridement completed, and frozen-section tissue examined

(93).

Evide'noe of acute inflammation is a reason for aborting the procedure until microbacterial cultures are available. Closing the wound over an antibiotic impregnated polymethylmethacrylate spacer makes subsequent re-entry of the knee easier in the event that cultures prove negative (93).

Removal of loose components is easy. Conversely, removal of adequately fixed components, especially when they are uncemented, is difficult. Polyethylene tibial and patellar components may be transected by an oscillating saw and the peg(s) removed. Use of an oscillating or a Gigli saw for the cement-bone interface is of value for metal component, although metal pegs may limit this. Several osteotomes can be inserted on top of one another to separate the metal components from bone (92).