Analysis of the causes of cage subsidence after oblique lateral lumbar interbody fusion / 中国骨伤

OBJECTIVE@#To observe the cage subsidence after oblique lateral interbody fusion (OLIF) for lumbar spondylosis, summarize the characteristics of the cage subsidence, analyze causes, and propose preventive measures.@*METHODS@#The data of 144 patients of lumbar spine lesions admitted to our hospital from October 2015 to December 2018 were retrospectively analyzed. There were 43 males and 101 females, and the age ranged from 20 to 81 years old, with an average of (60.90±10.06) years old. Disease types:17 patients of lumbar intervertebral disc degenerative disease, 12 patients of giant lumbar disc herniation, 5 patients of discogenic low back pain, 33 patients of lumbar spinal stenosis, 26 patients of lumbar degenerative spondylolisthesis, 28 patients of lumbar spondylolisthesis with spondylolisthesis, 11 patients of adjacent vertebral disease after lumbar internal fixation, 7 patients of primary spondylitis in the inflammatory outcome stage, and 5 patients of lumbar degenerative scoliosis. Preoperative dual-energy X-ray bone mineral density examination showed 57 patients of osteopenia or osteoporosis, and 87 patients of normal bone density. The number of fusion segments:124 patients of single-segment, 11 patients of two-segment, 8 patients of three-segment, four-segment 1 patient. There were 40 patients treated by stand-alone OLIF, and 104 patients by OLIF combined with posterior pedicle screw. Observed the occurrence of fusion cage settlement after operation, conducted monofactor analysis on possible risk factors, and observed the influence of fusion cage settlement on clinical results.@*RESULTS@#All operations were successfully completed, the median operation time was 99 min, and the median intraoperative blood loss was 106 ml. Intraoperative endplate injury occurred in 30 patients and vertebral fracture occurred in 5 patients. The mean follow-up was (14.57±7.14) months from 6 to 30 months. During the follow-up, except for the patients of primary lumbar interstitial inflammation and some patients of lumbar spondylolisthesis with spondylolisthesis, the others all had different degrees of cage subsidence. Cage subsidence classification:119 patients were normal subsidence, and 25 patients were abnormal subsidence (23 patients were gradeⅠ, and 2 patients were gradeⅡ). There was no loosening or rupture of the pedicle screw system. The height of the intervertebral space recovered from the preoperative average (9.48±1.84) mm to the postoperative average (12.65±2.03) mm, and the average (10.51±1.81) mm at the last follow-up. There were statistical differences between postoperative and preoperative, and between the last follow-up and postoperative. The interbody fusion rate was 94.4%. The low back pain VAS decreased from the preoperative average (6.55±2.2 9) to the last follow-up (1.40±0.82), and there was statistically significant different. The leg pain VAS decreased from the preoperative average (4.72±1.49) to the final follow-up (0.60±0.03), and the difference was statistically significant (t=9.13, P<0.000 1). The ODI index recovered from the preoperative average (38.50±6.98)% to the latest follow-up (11.30±3.27)%, and there was statistically significant different. The complication rate was 31.3%(45/144), and the reoperation rate was 9.72%(14/144). Among them, 8 patients were reoperated due to fusion cage subsidence or displacement, accounting for 57.14%(8/14) of reoperation. The fusion cage subsidence in this group had obvious characteristics. The monofactor analysis showed that the number of abnormal subsidence patients in the osteopenia or osteoporosis group, Stand-alone OLIF group, 2 or more segments fusion group, and endplate injury group was higher than that in the normal bone mass group, OLIF combined with pedicle screw fixation group, single segment fusion group, and no endplate injury group, and the comparison had statistical differences.@*CONCLUSION@#Cage subsidence is a common phenomenon after OLIF surgery. Preoperative osteopenia or osteoporosis, Stand-alone OLIF, 2 or more segments of fusion and intraoperative endplate injury may be important factors for postoperative fusion cage subsidence. Although there is no significant correlation between the degree of cage subsidence and clinical symptoms, there is a risk of cage migration, and prevention needs to be strengthened to reduce serious complications caused by fusion of cage subsidence, including reoperation.

Factors Affecting Postoperative Sagittal Alignment after Lateral Lumbar Interbody Fusion in Adult Spinal Deformity: Posterior Osteotomy, Anterior Longitudinal Ligament Rupture, and Endplate Injury

STUDY DESIGN: Prospective cohort study. PURPOSE: To identify factors that affect sagittal alignment correction in lateral lumbar interbody fusion (LIF) surgery for adult spinal deformity (ASD) and to investigate the degree of correction in each condition. OVERVIEW OF LITERATURE: LIF is a useful procedure for ASD, but the degree of correction can be affected by posterior osteotomy, intraoperative endplate injury, or anterior longitudinal ligament (ALL) rupture. METHODS: Radiographical data for 30 patients who underwent LIF for ASD were examined prospectively. All underwent two-stage surgery (LIF followed by posterior fixation). Radiographical parameters were measured preoperatively, after LIF, and after posterior fixation; these included the segmental lordotic angle, lumbar lordosis (LL), and other sagittal alignment factors. RESULTS: LL was corrected from 16.5°±16.7° preoperatively to 33.4°±13.8° after LIF (p<0.001) and then to 52.1°±7.9° following posterior fixation (p<0.001). At levels where Schwab grade 2 osteotomy was performed, the acquired segmental lordotic angles from the preoperative value to after posterior fixation and from after LIF to after posterior fixation were 19.5°±9.2° and 9.9°±3.9°, respectively. On average, 12.4° more was added than in cases without osteotomy. Endplate injury was identified at 21 levels (19.4%) after LIF, with a mean loss of 3.4° in the acquired segmental lordotic angle (5.3°±8.4° and 1.9°±5.9° without and with endplate injury, respectively). ALL rupture was identified at seven levels (6.5%), and on average 19.3° more was added in these cases between the preoperative and postoperative values than in cases without ALL rupture. CONCLUSIONS: LIF provides adequate sagittal alignment restoration for ASD, but the degree of correction is affected by grade 2 osteotomy, intraoperative endplate injury, and ALL rupture.

Precautions for Combined Anterior and Posterior Long-Level Fusion for Adult Spinal Deformity: Perioperative Surgical Complications Related to the Anterior Procedure (Oblique Lumbar Interbody Fusion)

STUDY DESIGN: Retrospective, single-center study. PURPOSE: We aimed to determine the perioperative complications of oblique lumbar interbody fusion (OLIF) as a first-stage procedure in combined anterior and posterior operation for adult spinal deformity (ASD) along with sagittal imbalance. Specifically, we aimed to identify the radiological and clinical types of perioperative surgical complications and the factors affecting these complications. OVERVIEW OF LITERATURE: OLIF has recently gained popularity, and there are several reports of good outcomes and only a few of complications with OLIF; however, a few studies have focused on the perioperative surgical complications of ASD along with sagittal imbalance. METHODS: The perioperative period was a 1-week interval between the anterior and posterior procedures. All patients underwent simple radiography and magnetic resonance imaging preoperatively and postoperatively. Cage placement was evaluated for displacement (i.e., subsidence and migration) and vertebral body fracture. Clinical patient complaints were evaluated perioperatively. Student t-test was used for data analysis. RESULTS: A total of 46 patients were included, totaling 138 fusion segments. A week after OLIF, 14 patients/33 segments (30.4%/23.9%) demonstrated endplate injury-associated cage placement change. Subsidence was the most common cage placement-related complication. As compared with patients without endplate injury, those with endplate injuries showed significantly larger correction angles and a higher proportion of them had larger height cages than the disk height in the full-extension lateral view. Although 32.6% of the patients experienced perioperative clinical complications, they were relatively minor and transient. The most common complication was severe postoperative pain (Visual Analog Scale score of >7), and hip flexor weakness spontaneously resolved within 1 week. CONCLUSIONS: OLIF yielded more than expected endplate injuries from treatment modalities for ASD along with sagittal imbalance. Therefore, surgeons should be cautious about endplate injury during OLIF procedures. It is difficult to accomplish lordosis correction via OLIF alone; therefore, surgeons should not attempt this impractical correction goal and insert an immoderate cage.