title: Ilizarov methodology for infected non union of the Tibia: Classic circular transfixion wire assembly vs. hybrid assembly.
abstract: BACKGROUND
  Conventional wire fixation of Ilizarov rings often fails to provide 90-90 configuration because of vital structures, which is essential for optimum stability. Hybrid assembly with half pins is an alternative. The aim of this study is to compare the results of Hybrid assembly with that of conventional classic circular transfixion wire Ilizarov assembly in 50 cases of infected nonunion of tibia between 1994 and 2003.
  
  
  METHODS
  This study includes two groups with 25 patients in each group: Group (A) conventional Ilizarov assembly and Group (B) hybrid Ilizarov assembly. Thirty-five cases developed infected nonunion following road traffic accidents while others after fall (6) bullet injury (4), infected osteosynthesis (3) and assault (2). There were 45 males and five females with mean age (18 to 56 years). All active cases (n=28) were treated by debridement including removal of implants in infected osteosynthesis. Twenty out of 22 cases in the quiescent group (non draining for last three consecutive months) were treated without open debridement; only two cases required open debridement for various reasons. All the cases were finally treated as atrophic aseptic nonunion with bone defect and were classified according to ASAMI. Type B1: length of the limb maintained with bone gap (14 cases in both Group A and B) and Type B3: combined shortening with defect (five and seven cases in Group A and B respectively), were treated by bifocal osteosynthesis. Only one case in the B3 group was treated by trifocal osteosynthesis to shorten the time. Type B2: segments in contact with limb shortening (total nine cases; five and four cases in Group A and B respectively) with shortening up to 2 cm (total five cases) were treated with monofocal osteosynthesis while shortening up to 5 cm and beyond (total four cases) were treated with bifocal osteosynthesis.
  
  
  RESULTS
  The cases were followed up for two to six years and the results were evaluated by Paley criteria of bony results (union, infection, deformity and leg-length discrepancy) and Functional Results (significant limp, equinus rigidity of the ankle, soft-tissue dystrophy, pain and inactivity). In both the groups, 24 cases out of 25, had excellent to good bony result with Group B having twice more excellent result than Group A. Functional results were found to be similar in both the groups. Although persistence of infection and Grade III pin tract infection (PTI) were slightly higher in Group B, complications like delayed consolidation of regenerate, refracture, deformity and aneurysm of vessel were less in this group.
  
  
  CONCLUSIONS
  Ilizarov methodology produced a satisfactory result in infected nonunion of the tibia. Hybrid assembly was a fruitful advancement in the Ilizarov armamentarium. The results were comparable to Conventional assembly in terms of docking site problems, corticotomy site problems, PTIs and other problems.
authors.affiliation: Department of Orthopedics, Assam Medical College, Dibrugarh - 786 002, Assam, India.
authors.forename: Ranjit Kr
authors.initials: RK
authors.lastname: Baruah