We reviewed the clinical database from January 2013 to December 2017, and 83 patients with femur bone defects were treated in our center. According to the inclusion and exclusion criteria, 56 patients were enrolled in this study. The inclusion criteria were patients with large segmental femur bone defects (> 3centimeters) which resulted from infection after debridement or acute bone loss, and treated with induced membrane technique. The exclusion criteria were patients age less than 18 years old or those who did not complete the treatment procedure.
In the first stage operation, hardwares were removed if presented. All the dead bone and infected scarred soft tissue were radically excised(Fig. 1A). Representative tissues were obtained from around the infected site (including the sinus tract) for microbiological cultivation.After radical debridement, the dead space were filled up with antibiotic impregnated PMMA cement spacer ( 0.5 gram gentamycin and 5 gram vancomycin in per 40 gram powder). The cement was applied in its doughy stage in order to form a smooth sheathing. Bone defects were stabilized with unilateral external fixator in 2 cases and antibiotic coated locking compressing plate in other 54 cases(Fig. 1B). Care must be taken when fixated with locking compressing plates, the antibiotic cement needs to coat the implant completely. Antibiotics administration lasted at least 2 weeks till the levels of WBC, ESR and CRP returned to normal limits according to the microbiological cultivation results and susceptibility tests. Postoperatively, partial weight-bearing and physical therapy was instructed.
Bone reconstruction was planned two months later after debridement, when the soft tissue condition is good and normalization of the laboratory values. SPECT was also carried out to exclude possible residual infection. Autologous bone was obtained from posterior iliac rest firstly. And then removing the PMMA spacer and bone grafting. The incision was opened according to the last surgery and microbiological cultures were taken again around the cement. Medullary canal was opened on two sides, the bone defect ends were decorticated and filled up with morselized cancellous autograft obtained from iliac crest or mixed with allograft according to recommended ratio(Fig. 1C). Thirty cases were fixated with intramedullary nail alone. As a precaution of nonunion when instability was noticed, another augmented locking compression plate was added between the defects in 26 patients. Prophylactic antibiotics were administered and continuously for another 2-week after the surgery according to the culture and drug sensitivity tests. Partial weight-bearing was allowed for patients with intramedullary nail and the weight was increased based on the radiographic result of bone healing. Patients were separated into two groups according the fixation method, the intramedullary nail group and augmented locking plate group.
Infection elimination was defined as normalization of laboratory values and resolution of the clinical features of infection (including discharge, redness, swelling, warm and pain). Bone union was defined as grafted bone materials fusion on four cortical side and move without pain(Fig. 1D). Follow-up examinations were carried out with a 4-week interval after the second stage of surgery. Then, a 8 weeks and 16 weeks interval until 2 years after the bone grafting.