Evaluation of Posterolateral Fusion Mass at Lumbosacral Junction Using Standard AP and Ferguson Radiographs
Journal of Korean Society of Spine Surgery (대한척추외과학회지)
Journal of Korean Society of Spine Surgery (대한척추외과학회지), Vol.8(3) : 235~241, 2001
Purpose : To evaluate the reliance of standard AP radiograph and Ferguson radiograph in assessment of instrumented lumbosacral fusion mass with intraobserver an d intraobserver reproducibilities. Materials and Methods : Postoperative standard AP radiograph and Ferguson radiograph were used to evaluate the fusion mass at the lumbosacral region of 44 consecutive patients who underwent posterolateral L4-S1 or L5-S1 instrumented fusion with pedicle screws & autogenous iliac bone graft. Ferguson radiograph was performed with the x-ray beam oriented toward the cranial portion at 40° relative to the x-ray table. All observations were performed independently by three observers, blinded to the history, diagnosis, and patient identity. The fusion mass was graded as solid, pseudarthrosis or questionable. A second review was repeated at 2 weeks after index review. Interobserver and intraobserver reproducibilities were analyzed with Fleiss' method.
Results : Ferguson radiographs were more reliable than standard AP radiographs in detecting the fusion mass. Kappa values with the interobserver reproducibility were higher in Ferguson radi ographs than in the standard AP radiographs. Kappa values with the intraobserver reproducibility of all three ob servers were higher in Ferguson radiographs than in the standard AP radiographs. The questionable fusion masses in the standard AP radiographs were revealed solid or pseudarthrosis in Ferguson radiographs in 67%. Conclusion : Ferguson radiograph is a more reliable method than standard AP radi ograph in evaluation instrumented posterolateral fusion mass in lumbosacral region.