अमूर्त

To Observe Changes in Callus Features Pre and Post Infection During Lengthening Over an Intramedullary Device.

MA Basit, Richa Sharma, and HR Song

Limb lengthening was described by Codivilla in the 19 century as a preferred procedure for limb-length discrepancies and has evolved greatly over the past 60 years(1,2).It is indicated when the discrepancy in length is greater than 5 to 6 cm(3,4). Lengthening over an intra-medullary device maintains alignment both during the distraction and consolidation phase. Thus reducing the number of percutaneous tracts and regenerate fractures. The device is removed when the desired length is achieved .We conducted a study on 62 patients over a period of four years. They were treated with limb lengthening over an intramedulary device. We compared changes in callus features in terms of shape, pattern and density both before and after infection. Limb lengthening over an intramedullary nail/rush pin was performed on 62 patients from 2004 to 2008 in our institution. The mean age was 20.34 years (3-48years) at the time of index procedure. We used UTN-AO nail and rush pins for lengthening .Circular external fixator was applied using both wires and half pins for tibial lengthening. All the radiographs were analyzed retrospectively by three different observers. The types and shapes were classified according to Ru Li et al.’s classification system. In infected cases changes in the callus pattern, shape and density were observed by serial radiographs every four weeks. And they were compared with the noninfected segments. We excluded patients who had a history of previous bone infection, open fracture, cases treated with bone transport, double level lengthening and severe bone deformity requiring gradual deformity correction and femoral segments were also excluded. All the patients were followed up for a minimum of two years post operatively62 patients (116 segments) were divided into three groups (Group A-noninfected, group B -superficial pin site infection, group C -deep intra-medullary infection). From 18 segments of (group B and C) staphylococcus aureus was recovered by culture. Group C differed significantly in its callus pattern (P<0.05) and density (P=0.0001) from both group (A and B). The callus shape and pattern follows a particular path during distraction osteogenesis. This pathway may get disturbed due to infection. Thus early radiographic changes like lucency, progressive heterogenousity and deficiency of the cortex can point towards underlying deep intra-medullary infection. Early recognition of these callus features along with other constitutional symptoms can help in early intervention. Thus, leading to timely diagnoses and appropriate treatment.