Radiographic Analysis of the Tibial Axis on the Antero-posterior and Lateral view of Knee

PURPOSE: The purpose of this study is to evaluate the use of plain knee films in assessing the position of tibial component after total knee arthroplasty. MATERIALS AND METHODS: Plain radiological antero-posterior(AP) and lateral view of tibia of 51 adults (mean age: fifty-years old) were taken. On AP view, the medial angles between tibia plateau and mechanical, anatomical and proximal anatomical axis of tibia were measured, and then correlation of each angle and the angle between the tibia plateau and anatomical axis were assessed. On lateral view, the posterior angle formed between the medial tibial plateau and anatomical, proximal anatomical axis, anterior and posterior cortex of proximal tibia were measured, and then correlation of each angle and the angle between the medial tibial plateau and anatomical axis were assessed. RESULTS: On tibial AP view, both axes had significant correlation(p<0.05) with the anatomical axis. The anatomical axis of proximal tibia was closest to it. On lateral view, all three axes had significant correlation(p<0.05) with anatomical axis. Among these, the anterior cortex of proximal tibia was closest to it. CONCLUSION: The position of the tibia component and posterior slope after total knee arthroplasty can be measured on plain knee X-rays using anatomical axis and the anterior cortex line of proximal tibia.

Unilateral versus Bilateral Pedide Scrwe Fixation in Lumbar Spinal Fusion / 대한정형외과학회잡지

OBJECTIVES: To determine if unilateral pedicle screw fixation is comparable to bilateral fixation in one-or two-segment lumbar spinal fusion. METHODS: Eighty-eight patients with spinal stenosis or spondylolisthesis were assigned to either unilateral or bilateral pedicle screw instrumentation groups. Demographic variables, preoperative diagnosis, number of fusion segments, and kinds of instrumentation used were similar between the two treatment groups. RESULTS: There were no significant differences between the two groups in terms of blood loss, clinical results, time at which fusion was complete, fusion rate, and complication rate. There were significant differences between the two groups in terms of duration of operating time, duration of hospital stay, medical expenses. The number of fusion segments or kinds of instrumentation did not affect the fusion rate, time at which fusion was complete, or clinical outcomes. Metal failure rate of unilateral fixation was higher in patients with spondylolytic spondylolisthesis than in patients with spinal stenosis. CONCLUSIONS: Unilateral pedicle screw fixation was as effective as bilateral pedicle screw fixation in lumbar spinal fusion independent of the number of fusion segments (one or two segments) or pedicle screw systems. Unilateral pedicle screw fixation is not recommended for spondylolytic spondylolisthesis patients who were treated with Gill' s decompression.