Comparative study of unilateral and bilateral cages with respect to clinical outcomes and stability in instrumented posterior lumbar interbody fusion.

Abstract

We sought to compare the clinical and radiological results of instrumented posterior lumbar interbody fusion (PLIF) using unilateral or bilateral polyetheretherketone cages and pedicle screws. One hundred eighty-seven cases of degenerative spine that had been followed for at least 18 months were reviewed retrospectively. In 88 cases (147 levels), one cage was inserted, and in 99 cases (152 levels), two cages were inserted. Visual analog scale, Oswestry disability index, and functional rating indices were measured. Lumbar lordosis, lumbar scoliotic and fusion level scoliotic angles, and stable fixation were determined before surgery and 12 months postoperatively on standing x-rays. Amounts of intra- and postoperative blood loss, total quantities transfused, and operation times were also evaluated. No significant differences were found between the two groups in terms of visual analog scale, Oswestry disability index, functional rating indices, lumbar lordosis, lumbar scoliotic angles, fusion level scoliotic angles, or fixation stabilities. However, the amounts of postoperative blood loss, total blood loss, and total transfusion for two-level PLIF using a unilateral cage were statistically smaller than those for two-level PLIF using bilateral cages. Times required for PLIF using a unilateral cage were also significantly shorter than those for PLIF using bilateral cages. Unilateral cage and bilateral pedicle screw insertion may be a good alternative surgical option because it provides adequate alignment, balance, and mechanical stability in addition to reducing operative time, blood loss, and transfusion requirements.