the following section describes the treatment procedure for patients with deep infection following tka using modified static spacers .
the original prosthesis was removed , followed by intensive irrigation and wide debridement of the infected soft tissue . a 36 fr - diameter straight thoracic catheter ( mallinckrodt medical , athlone , ireland ) and a steinmann pin measuring 3.0 mm in diameter and 22 cm in length
vancomycin ( 2 g ) was then added to the gentamicin bone cement ( depuy , warsaw , in , usa ) . at the late liquid stage of the cement ,
the steinmann pin was inserted into the tube , and the prepared cement was delivered through the tube . during this procedure ,
the tube was removed from the cement rod using a surgical knife . finally , a cement rod measuring 9 mm in diameter and 22 cm in length was formed ( fig .
an entry hole was created at the center of the distal femur and proximal tibia for the insertion of the cement rod .
the rod was then inserted into the femur and tibia through this hole . during insertion
, it was important to place the center of the cement rod on an imaginary joint line .
the proximal medullary canal of the tibia was filled with antibiotic - impregnated cement up to the surface of the proximal tibia , while the surgical assistant maintained proper anatomic alignment and joint space .
the space between the cement of the distal femur and the proximal tibia was filled with more antibiotic - impregnated cement .
finally , the suprapatellar pouch and medial and lateral gutter space were filled with antibiotic - impregnated cement to reduce soft tissue adhesion ( fig .
cylinder splint immobilization was required for three days after the operation , after which a fixed - angle knee brace was used and toe - touching ambulation was allowed until the reimplantation surgery .
from april to november 2007 , the authors performed the static technique in four patients using the novel antibiotic - impregnated cement rod for the treatment of infected tka ( culture : staphylococcus in three cases and no bacteria in one case ) .
follow - up laboratory studies , including erythrocyte sedimentation rate and c - reactive protein , culture study via knee aspiration and a frozen biopsy from the second - stage operation ( < 5 polymorpho - leukocytes / high power field ) were performed to confirm successful eradication of the infection .
the second - stage reimplantation was performed when all the criteria for the validation of infection control were met ( fig .
the second - stage reimplantation was performed using the rectus snipping approach , and more than 90 of flexion was obtained intra - operatively . in all four patients ,
no re - infection was evident after two and a half years of follow - up .
the range of motion of the knee joints were respectively improved from 50 to 80 , 95 , and 100 , and the knee society scores were 70 , 86 , 65 , and 84 , respectively , in the last follow - up evaluation . fehring et al.8 ) emphasized the importance of resting the joint in septic joint conditions .
others also reported that the static spacer technique provides more stability than the mobile spacer technique in patients with severe bone loss.5,8 ) the main advantage of this technique is the maintenance of a normally aligned lower limb during the interval period .
this maintains knee stability in combination with early muscle strengthening exercises , including quadriceps setting exercise , and enables the patient to comfortably dress and manage him / herself during the intervening period .
the cement rod and static spacer provide a stable gap between the femur and tibia , thereby minimizing soft tissue contracture and shortening of the lower limb .
in addition , symmetric maintenance of the soft tissue of both medial and lateral gutters requires no additional soft tissue balancing at the second - stage reimplantation .
the additional cost of a metal nail , however , and the difficulty in infection control due to biofilm formation around the metal nail can be troublesome . in addition , a metal nail can not be removed easily at the second stage reimplantation due to its hardness , and soft tissue adhesion of the femoral or tibial medullary canals . on the other hand ,
an antibiotic - impregnated cement rod enjoys advantages , such as inexpensive antibiotic delivery to the marrow spaces and easy removal by using a hercules cutter .
in addition , a static spacer is anchored to the cement rod , which can prevent spacer migration and bone erosion .
this feature is believed to generate less cement wear debris than with the conventional static spacer or mobile articulating spacer technique . during the conduct of the antibiotic - impregnated cement rod technique ,
antibiotic - impregnated cement was applied to the proximal tibia , distal femur , joint gap space , suprapatellar pouch , and both gutters in a stepwise manner .
this technique enables easy removal of the cement and reduced soft tissue adhesion at second - stage reimplantation .
 the two - stage exchange arthroplasty ( one- or two - stage ) is believed to be the gold standard for the management of infections following total knee arthroplasty . 
 we herein report a novel two - stage exchange arthroplasty technique using an antibiotic - impregnated cement intramedullary nail , which can be easily prepared during surgery using a straight thoracic tube and a steinmann pin , and may provide additional stability to the knee to maintain normal mechanical axis . 
 in addition , there is less pain between the period of prosthesis removal and subsequent reimplantation . 
 less soft tissue contracture , less scar adhesion , easy removal of the cement intramedullary nail , and successful infection control are the advantages of this technique . 
SURGICAL TECHNIQUE
DISCUSSION