Factors Affecting Segmental Lordotic Angle After Posterior Lumbar Interbody Fusion Using Metal Cage / 대한척추외과학회지

ABSTRACT

STUDY DESIGN: This is a retrospective study. OBJECTIVES: We tried to find out what kind of factors affect the segmental lordotic angle improvement after performing posterior lumbar interbody (PLIF) fusion using a metal cage. The study was done using radiographic measurements. SUMMARY OF LITERATURE REVIEW: For degenerative spinal disease, PLIF with using a metal cage is an effective way to fuse and restore segmental lordosis of the lumbar spine. MATERIALS AND METHODS: The study included 104 patients (65 males, 39 females). Radiographs of the antero-posterior, lateral, flexion and extension views that were taken during the preoperative period and the follow-up 6 months were evaluated for the L4-5 segmental lordosis angle, cage invagination, cage position and disc height. Then, statistical analysis was performed using the Pearson method to determine which factors affected the segmental lordotic angle correction. RESULTS: The increase of the anterior disc height on the postoperative lateral radiograph (gamma=0.303, p<0.01) and the increase of lordosis on the preoperative extension radiograph (gamma=0.384, p<0.01) showed statistically positive correlation with the increase of the postoperative segmental lordosis angle. When comparing between the 4 degrees and 8 degrees cages, the more angle the cage had, the more segmental angle was restored and this was statistically correlated (P<0.05). However, the amount of segmental lordosis angle correction was not as much as the angle of the cage that was used. Other factors such as cage invagination and cage position didn't show statistical correlation. CONCLUSIONS: Posterior lumbar interbody fusion using a metal cage is useful method for restoring the lumbar segmental lordosis angle only if the disc is flexible enough to be distracted (ED note: distracted is the word you want?) sufficiently intraoperatively or if it allows good segmental lordosis, as seen on the preoperative extension radiograph. Correction of the segmental lordosis angle using a wedged cage with a larger angle was not always satisfactory because it did not restore as much angle as the angle of cage that was used.