Bone Transport In Chronic Infected Non-Union Using AO External Fixator

摘要

We used AO external fixator for bone transport in 4 patients with chronic osteomyelitis after trauma including 2 cases with femoral shaft fracture (type I and III A), one femoral supracondylar fracture (type III B) and one case with fracture of the proximal of tibia (plateau) type III B. The mean age of the patients was 34.7 years (24-46 years). All fractures were open because of car accident. Internal fixation had been initially carried out for the patients with femoral fracture and calcaneal pin traction for the patient with plateau fracture. The mean time between fracture and the onset of bone transport external fixation was 85 days (24-180 days). All the patients were culture-positive, identified the gram negative bacteria including Pseudomona, E-coli and Enterobacter as the causative pathogens. The mean of bone defects was 10.2 centimeters (7-14 centimeters).The mean duration of bone transport was 134 days (77-210 days). The total duration of treatment from placing AO external fixator until bringing out the device was 11-25 months (mean, 19.2 months). According to our experience when bone transport carried out by AO external fixator and with use of a five-to-seven day latency period and a rate of distraction of one millimeter per day, approximately 1.9 month treatment (including time for distraction and healing) was required per each centimeter bone defect which is less than the duration of treatment using Ilizarov technique for bone transport requiring 2 to 3 months treatment per centimeter. In our experience major intercalary defects in femur and also tibia have been bridged and new bone has formed in the defect with concomitant restoration of the osseous integrity and alignment of the limb. Introduction Infected non-union is one of the most problematic complications of long bone fractures requiring extensive reconstructive surgery in many cases. The conventional treatment includes extensive debridement, external fixation, bone graft and soft tissue coverage. Radical resection of necrotic bone and bone transport is an alternative treatment (1, 2). In this method, bone defects are closed from within sliding a bone fragment internally, producing distraction osteogenesis behind it until the defect is bridged. In most of previous studies regarding bone transport, the Ilizarov technique has been used especially in chronic osteomyelitis of tibia and average bone defects of 6-8 centimeters approximately (3,4,5,6,7,8,9,10,11,12,13,14). In previous studies, using Ilizarov technique for bone transport has been reported to have good outcomes regarding the management of infection but with considerable soft tissue injuries in large osseous defects particularly in femur. Schmidt, Wittek, Faschingbauer, et al reported high rate of soft tissue injuries using Ilizarov technique bone transport in femur and recommended to use AO external fixator with arc of 90 or 120 degree(14). There is a paucity of literature regarding the use of AO external fixator for bone transport especially in femoral bony defects due to osteomyelitis. In this study the authors report 4 patients suffering from chronic osteomyelitis successfully treated using AO external fixator for bone transport in Imam Hossein Medical Center. Material and Methods We used AO external fixator for bone transport in 4 patients with chronic osteomyelitis after trauma. The primary lab tests including CBC, ESR, CRP were requested for all the patients and then were treated by empiric antibiotic therapy. In cases with hemoglobin less than 10 g/dl blood was transfused in order to reach hemoglobin to more than 10 g/dl. All were prescribed high protein regimen, and then after 1 week we carried out sequestrectomy and bone transport. Technique of surgery: After adequate blood reservation and with regard to plain radiography, methylen blue injection the day before surgery and the appearance of bone during operation, i.e., hemorrhage while osteotomy, we defined the extent of bone resection. We t