Comparative Evaluation of Linear Rail System and Ilizarov Ring Fixator in the Management of Infected Tibial Nonunion: A Prospective Comparative Study

Abstract

Background: One of the most challenging conditions seen in orthopedics is infected nonunion of the tibia due to its complexities associated with persistent infection, poor vascularity, bone loss, deformity, limb-length discrepancy and compromised soft-tissue coverage. In such cases, a successful treatment requires eradication of infection, radical removal of nonviable bone, restoration of mechanical stability and, when required, reconstruction of the resultant bone defect. Ilizarov circular external fixation has been widely used for the management of infected tibial nonunion. It permits compression, distraction, deformity correction and bone lengthening. An alternative method for managing such cases is Linear Rail systems, that provides external fixation and may offer advantages in terms of application, postoperative management and patient comfort.

Aim: To compare the clinical and radiological outcomes of linear rail system (LRS) fixation and Ilizarov ring fixation in the treatment of infected tibial nonunion.

Materials and Methods: This prospective comparative study included 34 patients with infected nonunion of the tibia involving the proximal, middle or distal third. Fourteen patients were treated with a linear rail system, 15 patients were treated with an Ilizarov ring fixator and 5 patients dropped out of study. Patients with infected nonunion with an implant in situ, infected nonunion of less than 9 months duration and patients with atrophic nonunion of another long bone, such as the femur, in the same limb were excluded. In the LRS group, radical debridement of the infected nonunion was performed, including excision of the infected bone segment and fibular osteotomy where required. The medullary canal was opened and acute docking of the healthy bone ends was achieved using the LRS. A proximal or distal corticotomy was subsequently performed depending upon the location of the docking site. Distraction at the corticotomy site was initiated after a latency period of 7 days, while compression was continued at the docking site. Patients treated with Ilizarov fixation underwent radical debridement followed by application of a standard Ilizarov frame, with compression, acute docking and/or distraction osteogenesis according to the bone defect and operative findings. Outcomes were assessed using union rate, time to union, ASAMI bone and functional scores, pin-tract infection and limb-length discrepancy.

Results: Fourteen of 14 patients in the LRS group achieved union, giving an observed union rate of 100%, whereas 12 of 15 patients in the Ilizarov group achieved union, giving an observed union rate of 80%. The mean time to union was approximately 6 months in the LRS group compared with 8 months in the Ilizarov group; giving an inference of overall ASAMI bone outcome be excellent in the LRS group and good in the Ilizarov group. The overall ASAMI functional outcome was predominantly good in the LRS group and fair in the Ilizarov group. Pin-tract infection occurred in one patient in the LRS group and three patients in the Ilizarov group. Limb-length discrepancy occurred in one patient in the LRS group and three patients in the Ilizarov group.

Conclusion: Both linear rail and Ilizarov external fixation are an effective management approach for infected tibial nonunion. In the present study, LRS fixation was associated with a higher observed union rate, shorter mean time to union, better overall ASAMI bone and functional outcomes and fewer reported complications. Therefore, LRS may represent a useful alternative to circular fixation in appropriately selected patients with infected tibial nonunion.