[Analysis of the causes of cage subsidence after oblique lateral lumbar interbody fusion].

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.

[Analysis of the causes and clinical results of vertebral fracture during oblique lateral lumbar interbody fusion].

OBJECTIVE: To analyze the causes of vertebral fracture during oblique lateral interbody fusion in the treatment of lumbar spondylopathy, summarize the clinical results, and propose preventive measures. METHODS: Retrospective analysis was made on the data of 8 cases of lumbar spondylopathy and vertebral fracture treated by oblique lateral interbody fusion in three medical centers from October 2014 to December 2018. All were female, aged from 50 to 81 years with an average of 66.4 years. Disease types included 1 case of lumbar degenerative disease, 3 cases of lumbar spinal stenosis, 2 cases of lumbar degenerative spondylolisthesis and 2 cases of lumbar degenerative scoliosis. Preoperative dual energy X-ray bone mineral density test showed that 2 cases had T-value >-1 SD, 2 cases had T-value -1 to -2.5 SD, and 4 cases had T-value <-2.5 SD. Single segment fusion was in 5 cases, two segment fusion in 1 case and three segment fusion in 2 cases. Four cases were treated with OLIF Stand-alone and 4 cases were treated with OLIF combined with posterior pedicle screw fixation. Postoperative imaging examination showed vertebral fracture, and all of them were single vertebral fracture. There were 2 cases of right lower edge fracture of upper vertebral body at fusion segment, 6 cases of lower vertebral body fracture at fusion segment, and 6 cases with endplate injury and fusion cage partially embedded in vertebral body. Three cases of OLIF Stand-alone were treated with pedicle screw fixation via posterior intermuscular approach, while one case of OLIF Stand-alone and four cases of OLIF combined with posterior pedicle screw fixation were not treated specially. RESULTS: The 5 cases of initial operation and 3 cases of reoperation did not show wound skin necrosis or wound infection. The follow-up time was from 12 to 48 months with an average of 22.8 months. Visual analogue scale (VAS) of low back pain was preoperative decreased from 4 to 8 points (averagely 6.3 points) and postoperative 1 to 3 points (averagely 1.7 points) at the final follow-up. Oswestry disability index (ODI) was preoperative 39.7% to 52.4% (averagely 40.2%), and postoperative 7.9% to 11.2% (averagely 9.5%) at the final follow-up. During the follow-up, there was no loosening or fracture of the pedicle screw system, and no lateral displacement of the fusion cage;however, the fusion cage at the vertebral fracture segment had obvious subsidence. The intervertebral space height of vertebral fracture segment was preoperaive 6.7 to 9.2 mm (averagely 8.1 mm), and postoperative 10.5 to 12.8 mm (averagely 11.2 mm). The improvement rate after operation was 37.98% compared to preoperative. The intervertebral space height at final follow-up was 8.4 to 10.9 mm (averagely 9.3 mm), and the loss rate was 16.71% compared with that after operation. At the final follow-up, interbody fusion was achieved in all cases except for one that could not be identified. CONCLUSION: The incidence of vertebral fracture during oblique lateral interbody fusion in the treatment of lumbar spondylopathy is lower, and there are many reasons for fracture, including preoperative bone loss or osteoporosis, endplate injury, irregular shape of endplate, excessive selection of fusion cage, and osteophyte hyperplasia at the affected segment. As long as vertebral fracture is found in time and handled properly, the prognosis is well. However, it still needs to strengthen prevention.

[Application of oblique lateral interbody fusion in the treatment of lumbar intervertebral disc degeneration in patients with Modic change and endplate sclerosis].

OBJECTIVE: To explore the feasibility and clinical effect of Stand-alone oblique lateral interbody fusion (OLIF) in the treatment of lumbar intervertebral disc degeneration with Modic changes and endplate sclerosis. METHODS: A retrospective analysis was performed on 16 cases with lumbar intervertebral disc degeneration with Modic changes and endplate sclerosis admitted to three medical centers from January 2015 to December 2018. There were 6 males and 10 females, the age ranged from 45 to 67 years old with an average of (55.48±8.07) years old, the medical history ranged from 36 to 240 months with an average of (82.40±47.68) months. The lesion sites included L2,3 in 2 cases, L3,4 in 5 cases, and L4,5 in 9 cases. All patients presented with chronic low back pain with lower limb neurological symptoms in 3 cases. All patients were treated by Stand-alone oblique lateral lumbar interbody fusion. Clinical and radiological findings and complications were observed. RESULTS: There was no vascular injury, endplate injury and vertebral fracture during the operation. The mean incision length, operation time, and intraoperative blood loss were(4.06±0.42) cm, (45.12±5.43) min, (33.40±7.29) ml, respectively. The mean visual analogue scale (VAS) of the incision pain was (1.14±0.47) at 72 hours after operation. There was no incision skin necrosis, poor incision healing or infection in patients. Sympathetic chain injury occurred in 1 case, anterolateral pain and numbness of the left thigh in 2 cases, and weakness of the left iliopsoas muscle in 1 case, all of which were transient injuries with a complication rate of 25%(4/16). All 16 patients were followed up from 12 to 36 months with an average of (20.80±5.46) months. The intervertebral space height was significantly recovered after operation, with slight lost during the follow-up. Coronal and sagittal balance of the lumbar spine showed good improvement at the final follow-up. There was no obvious subsidence or displacement of the cage, and the interbody fusion was obtained. At the final follow-up, Japanese Orthopaedic Association(JOA) score and Oswestry disability index(ODI) were significantly improved. CONCLUSION: As long as the selection of case is strict enough and the preoperative examination is sufficients, the use of Stand-alone OLIF in the treatment of lumbar intervertebral disc degeneration with Modic changes and endplate sclerosis has a good results, with obvious clinical advantages and is a better surgical choice.

[Case-control study on endplate injury of lumbar spine with two different intervertebral fusion methods].

OBJECTIVE: To summarize and compare the endplate injury occurrence characteristics and clinical results of transforaminal intervertebral fusion combined with pedicle screw fixation through intermuscular approach and oblique lateral intervertebral fusion combined with pedicle screw fixation in the treatment of lumbar disease. METHODS: A retrospective analysis of 213 cases of lumbar disease admitted from January 2016 to June 2019, including 73 males and 140 females. The age ranged from 24 to 81 years old, with an average of(54.9±10.5) years old. The courses of disease ranged from 6 to 180 months, with an average of (40.30±28.71) months. There were 35 cases of degenerative lumbar intervertebral disc disease, 22 cases of giant lumbar disc herniation, 15 cases of discogenic low back pain, 9 cases of primary lumbar intervertebral inflammation at the turn of inflammation, 52 cases of lumbar spinal stenosis, 47 cases of lumbar degenerative spondylolisthesis, 33 cases of lumbar spondylolysis with or without spondylolisthesis. There were 191 cases of single-segment lesions, including 5 cases on L2, 3, 24 cases on L3, 4, 162 cases on L4, 5. And there were 22 cases of two-segment lesions, including 3 cases on L2, 3 and L3, 4, and 19 cases on L3, 4 and L4, 5. One hundred and ten cases were taken by bilateral pedicle screw fixation and interbody fusion under the posterior muscle space approach (abbreviated as posterior fusion group), and 103 cases were taken by oblique lateral interbody fusion combined with bilateral pedicle screw fixation under the posterior muscle space approach (oblique lateral fusion group). Observed the characteristics of endplate injury in the two groups, and compared the clinical and imaging results and complications of the two groups. RESULTS: There were 8 cases of endplate injury occurred in 9 segments in the posterior fusion group. According to the number of cases, the incidence rate was 7.27%(8/110), 1 case was male, 7 cases were female, with an average age of (63.22±3.51) years old. Among the 8 cases, there were 7 cases of bone loss or osteoporosis before the operation, 5 cases using banana fusion cages, 3 cases using anatomical fusion cages. Three cases occurred in the upper endplate of the vertebral body and 6 cases in the inferior endplate of the vertebral body. In the oblique lateral fusion group, there were 21 cases of endplate injury in 24 segments, and the incidence rate was 20.39%(21/103). There were 4 males and 17 females, with an average age of (62.50±5.02) years old. Among the 21 cases, 16 cases were bone loss or osteoporosis before operation. There were 5 cases used large fusion cages, 4 cases had abnormal endplate anatomy, and 3 cases had iliac crest hypertrophy. It occurred in 20 segments of the upper endplate of the vertebral body, and 4 segments of the lower endplate of the vertebral body. Two of the 21 cases of endplate injury combined with vertebral body fractures. The incidence of endplate injury of the posterior fusion group was significantly lower than that of the oblique lateral fusion group. No incision infection occurred in the two groups, the follow-up time was ranged from 12 to 48 months, and the median follow-up period was 12 months. In the follow-up, 22 cases occurred fusion cage subsidence in the posterior fusion group, 43 cases in the oblique lateral fusion group, and 1 case in each group occurred fusion cage displacement. There was no loosening, displacement or breakage of the internal fixation. The incidence of complications in the oblique lateral fusion group 33.98%(35/103) was significantly higher than that in the posterior fusion group 23.64%(26/110), P=0.039. The height of the intervertebral space in both groups recovered well after the operation, but it was lost to varying degrees during follow-up. The fusion rate of the posterior fusion group was 94.5%(104/110), and 96.1%(99/103) in the oblique lateral fusion group(P=0.083). At the latest follow-up, the clinical symptoms of the two groups of patients were significantly improved. CONCLUSION: Two methods in treating single or two-segment lumbar spine lesions obtained good clinical effects. The characteristics of endplate injury in the two fusion methods are not completely the same. Although the endplate injury did not affect the final clinical results of the two fixed fusion methods, it still needs to be paid attention to and emphasize the prevention and effective treatment of endplate injury, especially for oblique lateral intervertebral fusion.

[Channel-assisted fixation and interbody fusion in treating recurrent lumbar disc herniation by muscle-splitting approach].

OBJECTIVE: To explore the clinical value and safety of unilateral pedicle screw fixation combined with contralateral translaminar facet screw fixation and interbody fusion by muscle-splitting approach treatment of recurrent lumbar disc herniation. METHODS: The clinical data of 51 patients with recurrent lumbar disc herniation treated from June 2012 to December 2017 were retrospectively analyzed. There were 32 males and 19 females, aged 34 to 64 years with an average of (51.11± 7.28) years. Lesions invoved L4,5 in 38 cases and L5S1 in 13 cases. All patients had a history of lower back pain and radiation pain of lower limbs(3 bilateral and 48 unilateral)and underwent unilateral pedicle screw combined with contralateral translaminar facet screw fixation and interbody fusion, among which 24 patients were treated through median incision approach (median incision group);other 27 patients were treated through muscle-splitting approach with channel-assisted exposure(muscle-splitting approach group). Operation time, intraoperative blood loss, postoperative drainage and incision length of the two groups were recorded. Visual analogue scale (VAS) was used to score the pain of lumbar incision at 72 h after operation, and JOA low back pain scoring system was used to evaluate the lumbar function preoperatively and at final follow-up. Imaging data were analyzed, including the changes in the height of intervertebral space of diseased segment before operation, 3 to 5 days after operation, and at final follow-up;Cobb angle changes in the coronal and sagittal planes of lumbar spine preoperatively and at final follow-up;multifidus area and multifidus fatty tissue deposition grade before and 12 months after operation; postoperative pedicle screw and laminar process screw position and intervertebral fusion condition. The complications of the two groups were compared. RESULTS: There was no statistical difference in operation time between two groups (P>0.05). Muscle-splitting approach group was better than median incision group in light of incision length, intraoperative blood loss and postoperative drainage volume (P<0.05). VAS score of lumbar incision pain at 72 h after operation was 1.61±0.54 in median incision group and 0.76±0.28 in muscle-splitting approach group(P<0.05). All patients were followed up for 12 to 84 (43.50±15.84) months. At final follow-up, the JOA scores of the two groups were significantly improved compared with those before operation(P<0.05). The rate of pedicle screw malposition was 6.25%(3/48) in medianincision group and 9.26%(5/54) in muscle-splitting approach group, there was no statistically significant difference between two groups (P>0.05). Rate of translaminar facet screw malposition in median incision group (12.50%) was significant less than the muscle-splitting approach group (18.52%)(P< 0.05). The height of the intervertebral space of the two groups was significantly restored 3 to 5 days after operation (P<0.05), and there was also a significant loss of height at final follow-up (P<0.05). At final follow-up, the balance of lumbar coronal plane and sagittal plane in two groups were improved very well (P<0.05). The comparison of the area and grade of the multifidus muscle in two groups 12 months after operation showed that obvious damage to the multifidus muscle were present in the median incision, while the multifidus muscle was less damaged by muscle-splitting approach (P<0.05). The fusion rate was 91.7%(22/24) in the median incision group and 92.6%(25/27) in muscle-splitting approach group(P>0.05). In median incision group, there were 1 case of intraoperative pedicle entry point fracture, 1 case of intraoperative dural tear and 1 case of postoperative nerve root injury;in muscle-splitting approach group, there were 1 case of intraoperative pedicle entry point fracture, 2 cases of intraoperative dural tear, 1 case of postoperative nerve root injury, 2 cases of incision epidermal necrosis and 1 case of poor incision healing. Nerve root injuries in the two groups were caused by incorrect positions of pedicle screws, the screws were immediately adjusted upon discovery. The nerve root symptoms were completely recovered 3 and 6 months after surgery. No incision infection was occurred in two groups. During the follow-up, no pedicle screw and laminar facet screw were loosened, displaced, broken, or intervertebral fusion cage moved forward and backward. The complication rate of 25.93% in muscle-splitting approach group was higher than 12.50% in the median incision group (P<0.05). CONCLUSION: Muscle-splitting approach is feasible for thetreatment of recurrent lumbar disc herniation with pedicle screw fixation combined with contralateral translaminar facet screw fixation and interbody fusion. Compared with the median incision approach, the muscle-splitting approach has the advantages of small incision, less trauma, less bleeding, rapid recovery. Also it can protect multifidus and do not increase the incidence of serious complications. Thus, it can be used as a choice for fixation and fusion of recurrent lumbar disc herniation.

[Analysis on the causes and prevention strategies of the vascular injury caused by the oblique lateral lumbar fusion].

OBJECTIVE: To analyze the causes of vascular injury occurred in oblique lateral interbody fusion for treating lumbar degenerative diseases, and put forward preventive measures. METHODS: There were 235 patients analyzed from October 2014 to May 2017 in five hospitals, who were treated with oblique lateral interbody fusion with or without posterior pedicle screw fixation. There were 79 males and 156 females with an average age of (61.9±13.5) years old (ranged from 32 to 83 years). There were 7 cases of vascular injury, including 4 cases of segmental vessel injury, 1 case of left common iliac artery injury, 1 case of left common iliac veininjury and 1 case of ovarian vein injury. RESULTS: The follow up time ranged from 6 to 36 months, averagely (15.6±7.5) months. There was no pedicle screw loosen or fracture. The low back pain VAS decreased from preoperative 6.7±2.3 to 1.4±0.8 at the latest follow-up, which was statistically difference(t=7.21, P=0.033). The ODI decreased from preoperative (36.5±7.7)% to (9.4±3.6)% at the latest follow-up, which was statistically difference (t=8.11, P=0.025). CONCLUSION: Oblique lateral interbody fusion technique provides a new method for minimally invasive fusion of lumbar internal fixation. However, it has a risk of vascular injury. In order to effectively prevent the occurrence of vascular injury, the operative indications and careful and meticulous operation should be strictly grasped.

Complications and Prevention Strategies of Oblique Lateral Interbody Fusion Technique.

OBJECTIVE: To analyze the early complications and causes of oblique lateral interbody fusion, and put forward preventive measures. METHODS: There were 235 patients (79 males and 156 females) analyzed in our study from October 2014 to May 2017. The average age was 61.9 ± 0.21 years (from 32 to 83 years). Ninety-one cases were treated with oblique lateral interbody fusion (OLIF) alone (OLIF alone group) and 144 with OLIF combined with posterior pedicle screw fixation through the intermuscular space approach (OLIF combined group). In addition, 137/144 cases in the combined group were primarily treated by posterior pedicle screw fixation, while the treatments were postponed in 7 cases. There were 190 cases of single fusion segments, 11 of 2 segments, 21 of 3 segments, and 13 of 4 segments. Intraoperative and postoperative complications were observed. RESULTS: Average follow-up time was 15.6 ± 7.5 months (ranged from 6 to 36 months). Five cases were lost to follow-up (2 cases from the OLIF alone group and 3 cases from the OLIF combined group). There were 7 cases of vascular injury, 22 cases of endplate damage, 2 cases of vertebral body fracture, 11 cases of nerve injury, 18 cases of cage sedimentation or cage transverse shifting, 3 cases of iliac crest pain, 1 case of right psoas major hematoma, 2 cases of incomplete ileus, 1 case of acute heart failure, 1 case of cerebral infarction, 3 case of left lower abdominal pain, 9 cases of transient psoas weakness, 3 cases of transient quadriceps weakness, and 8 cases of reoperation. The complication incidence was 32.34%. Thirty-three cases occurred in the OLIF alone group, with a rate of 36.26%, and 43 cases in the group of OLIF combined posterior pedicle screw fixation, with a rate of 29.86%. Fifty-seven cases occurred in single-segment fusion, with a rate of 30.0% (57/190), 4 cases occurred in two-segment fusion, with a rate of 36.36% (4/11), 9 cases occurred in three-segment fusion, with a rate of 42.86% (9/21), and 6 cases occurred in four-segment fusion, with a rate of 46.15% (6/13). CONCLUSION: In summary, OLIF is a relatively safe and very effective technique for minimally invasive lumbar fusion. Nonetheless, it should be noted that OLIF carries the risk of complications, especially in the early stage of development.