Failure resulting from a recurrent infection in total knee arthroplasty (TKA) is a challenging problem. Knee arthrodesis is one treatment option, however fusion is not always successful, as there is huge bone defect. The authors reports a new arthrodesis technique that uses a bundle of flexible intramedullary rods and an antibiotic-loaded cement spacer. There were 13 cases of arthrodesis due to recurrent periprosthetic joint infection, which were performed by the first author (WS Cho) at Asan Medical Center in Seoul from 2005 to 2014. All previous prosthetic components were removed and cement was thoroughly excised using a small osteotome. Two stage operation was done in most of cases. After thorough debridement, antibiotics loaded cement was inserted in first stage, flexible intramedullary rods were inserted retrogradely in the femoral side with the knee in flexion under fluoroscopy guidance. After filling the femoral intramedullary canal, the rods were then driven back securely into the tibial medullary canal. We aimed for as much rod length as possible to maximize stability. After 6 weeks of first stage operation, the rods of the femoral and tibial sides were arranged such that they overlapped and interdigitated to maximize mechanical strength, maintain the limb length and keep the rotational alignment. The interdigitating rod ends were tightly fixed using two (or three) cerclage wires. Antibiotic-loaded cement was filled into the knee joint space so that the cement is fit to the irregular contour of the femur and tibia, which was resulted from the severe bone loss. Postoperatively, patients were allowed to weight bear as tolerated.Purpose
Methods
Most of revision TKA needs bone reconstruction. The success of revision TKA depends on how well the bone reconstruction can be done. The method of reconstruction includes bone cementing, metal augmentation, allogenic bone graft, APC and tumor prosthesis, etc. In moderate to severe bone defect, allograft is needed. However, allogenic bone graft is surgically demanding and needs long operation time, which is very risky to the elderly patients. The authors revised an alternative method of bone defect reconstruction using cementing method with multiple screws augmentation. There were 12 cases of patients with large defect which could not be reconstructed with metal augment from April 2012 to April 2014. The authors performed 3 to 5 screws fixation on the defect site. Sclerotic bone is prepared with burring for better cementing. 3 ∼ 5 screws according to the size of defect. The length of screw fixation was determined as deep to the bone until stable fixation just beneath the implant. When drilling for the screw insertion, intramedullary guide is put into the medullary canal so as not to interfere with implant insertion. The defect is filled with cement during prosthesis fixation. Weight bearing was permitted on postoperative 3rd day, as usual manner of primary TKA.Purpose
Methods
The bone defect reconstruction is the first step of successful primary or revision TKA in case of large bone defect. If the defect is not reconstructed adequately, we can neither preserve knee joint function nor guarantee long survival of the implant. Allogeneic bone graft is known to be the treatment of choice in large defect. However the surgical technique is demanding and incorporation failure is constant issue of the allogeneic bone graft. We propose new bone defect reconstruction technique using multiple screws and cement. From April 2012 to April 2014, 12 patients with large defect which could not be reconstructed with metal augment were involved in this study. The bone defect type was 10 cases of 2A and 2 cases of 2B according to AORI (Anderson Orthopedic Research Institute) classification. The defect was reconstructed with multiple screws and cementing technique by single surgeon (WS Cho). Average follow-up period was 15 months. (24 ∼ 1 month)Introduction
Material and method
Revision of infected TKA is one of the most challenging operation as the surgeon should achieve two goals, ie eradication of infection and restoration of function. For the eradication of infection, a minimum of two operations are needed in most of cases. First stage of revision is meticulous debridement and insertion of antibiotic loaded cement. During arthrotomy, thick fibrous and granulation tissues which is located in the suprapatella pouch, lateral site to the patella tendon and posterior joint space should be removed so as to get better exposure, to get rid of infection source and to get better functional result. During debridement, I use highly concentrated antibiotic saline (1 gm vancomycin in 10cc saline), for irrigation of the operation field. I also pack the opening of the medullary canal so as to prevent the debris from entering into the medullary canal. I use antibiotics with the ratio of 1:3. To reduce the dead space in the medullary canal I insert a dowel shaped antibiotic loaded cement spacer made from one pack of cement and fill the medullary canal. Thereafter two packs of cement are used to make a block to fill the gap between femur and tibia. The cement block should be large enough to cover the distal femur and proximal tibia so as not to cause bone defect and knee dislocation during walking. After first stage of operation, antibiotics are administered for 4∼8 wks until the CRP levels become normalized and clinical findings show no sign of infection. The 2nd stage of operation is planned when clinical and laboratory signs of infection subside. The decision whether to reimplant the prosthesis or not is based on the operation findings and polymorphonuclear cell count on frozen section. However operation findings are considered more important than the frozen section results for reimplantation. If operative findings are clean, I do reimplanation even though the polymorphonuclear cell count is more than 5 on high power field(hpf) on frozen section. I have adopted numbering system to take specimen. Number 1 is specimen from suprapatella pouch, No 2 is that from gap between the femur and tibia, No 3 is that from femoral intramedullary canal, No 4 is that from tibial intramedullary canal, and No 5 is that from most unhealthy site. In a retrospective analysis of 16 cases which received reimplantation despite of the prescence of more than five polymorphonuclear cells on intra-operative frozen sections, none of the cases had recurrence of infection at a final follow up of 2 years. The femoral medullary canal was the most prevalent site for higher polymorphonuclear cell count. In conclusion, indication is the first step for successful reimplantion. Two stage revision is recommended and meticulous debridement is utmost important in first stage operation. Block type antibiotic loaded cement is sufficient for a good result. Clinical, laboratory and operative findings are more important than polymorphonuclear cell count on frozen section to decide reimplantation. I propose numbering system of the specimen site for frozen section, just as in tumor surgery.
