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Study Design: Prospective cohort study., Objective: To assess the differences in the clinical and radiological outcomes between oblique lateral interbody fusion (OLIF) and minimally invasive transforaminal lumbar interbody fusion (MI-TLIF)., Summary of Background Data: Nowadays, there is still a controversy regarding whether OLIF is superior to MI-TLIF in the management of degenerative lumbar disease., Methods: Between August 3, 2019 and February 3, 2020, 137 patients were assigned to OLIF or MI-TLIF at their request and the surgeon's discretion: 71 in the OLIF group and 66 in the MI-TLIF group. The perioperative data, patient-reported outcomes, radiographic outcomes, and complications were compared between the two groups., Results: The OLIF group showed shorter operation time (110.5 vs.183.8 minutes, P < 0.001), lesser estimated blood loss (123.1 vs. 232.0 mL, P < 0.001), shorter length of hospital stay (5.5 vs. 6.7 days, P < 0.001), and lower serum creatine kinase (CK) (1 day postoperatively) (376.0 vs. 541.8 IU/L, P < 0.01) than that of MI-TLIF group. Both groups showed no significant differences in the visual analog scale (VAS) scores of lower back and leg pain and the Oswestry Disability Index (ODI) scores preoperatively and at 1, 3, and 12 months postoperatively, respectively (P > 0.05). Compared with the MI-TLIF group, the OLIF group showed better restoration of disc height (DH) (4.7/4.6/4.7 vs. 3.7/3.7/3.7 mm, P < 0.01) and lumbar lordosis angle (LLA) (10.5°/10.8°/11.1° vs. 5.8°/5.7°/5.3°, P < 0.001), but not the value of segmental lordosis angle (SLA) (P > 0.05) at 1 day, 1 month, and 1 year postoperatively, respectively. The complication rate of OLIF was higher than that of MI-TLIF (29.4% vs. 9.7%, P < 0.01)., Conclusion: Compared with MI-TLIF, OLIF showed similar results in terms of patient-reported outcomes, restoration of SLA and fusion rate, and superior results with respect to restoration of DH and LLA, operation time, estimated blood loss, length of hospital stay, and serum CK levels (1 day postoperatively). Even though the complication rate of OLIF is higher than that of MI-TLIF, it does not bring persistent and substantial damage to the patients.Level of Evidence: 3., (Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc.)

Oblique lateral lumbar interbody fusion (OLIF) has been extensively used, with satisfactory outcomes for the treatment of degenerative lumbar disease. This article aims to demonstrate a modified lateral approach, also known as the anteroinferior psoas (AIP) technique for OLIF, which is expected to enhance security by operating under direct vision. The core procedures of our technique are as follows. First, a minimal skin incision is recommended 2 cm backward compared with the normal incision of OLIF, facilitating the oblique placement of the working channel and the orthogonal maneuver for the cage placement. Second, two special custom-made retractors, as an alternative to the index finger, are used to pull the psoas muscle to the dorsal side and pull the abdominal organs together with extraperitoneal fate to the ventral side under direct visualization, making the exposure of the working channel convenient and safe and avoiding radiation exposure. Third, the anterior border of the psoas is bluntly dissected and retracted backwards, obviously enlarging the retroperitoneal anatomic corridor and then expanding clinical indications of OLIF. The benefits of this technique include that it has a short learning curve, satisfactory clinical outcomes, and low risk of perioperative complications., (© 2021 The Authors. Orthopaedic Surgery published by Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.)

Objective: The aim of the present paper was to evaluate cases of lumbar degenerative diseases treated with oblique lateral interbody fusion (OLIF) using a modified lateral approach (i.e. anteroinferior psoas exposure under direct vision) and to analyze the effect and safety of this approach., Methods: From June 2016 to April 2019, a total of 226 patients with an average age of 65.5 ± 16.2 years (98 men and 128 women) with degenerative lumbar diseases who underwent the AIP approach of OLIF were followed up and analyzed retrospectively. Data concerning operative and clinical parameters were collected, including operative time, intraoperative estimated blood loss, duration of postoperative hospital stay, and time to ambulation after surgery. For the assessment of clinical outcomes, the visual analogue scale (VAS) score (for back pain) and the Oswestry disability index (ODI) were calculated. Complications were also recorded as surgical exposure approach-related complications. More than 6 months after surgery, 132 patients consented to having MRI examinations to evaluate the psoas muscle atrophy when they were followed up., Results: The mean operative time was 82.5 ± 31.6 min. The mean operative time for each segment of OLIF was 43.3 ± 15.5 min. The mean blood loss was 48.0 ± 11.6 mL. The mean blood loss for each segment of OLIF was 25.3 ± 10.1 mL. No patients needed blood transfusion intraoperatively or postoperatively. The mean hospital stay was 4.1 ± 2.1 days. All patients were followed up for 12-31 months (mean 18.2 months). Clinical assessment showed that the VAS and ODI scores at 6 months after surgery were markedly lower than the preoperative scores (P < 0.001) but did not differ from the scores at the final follow-up (P > 0.05). There was no significant difference in percentage changes of the cross-sectional area of the lean psoas muscle and the T2 signal intensity ratio of gross psoas to quadratus lumborum muscles between the left side (operative side) and the right side (nonoperative side) (P > 0.05). A total of 11 surgical exposure approach-related complications were reported, with an incidence of 4.9%: transient thigh pain/numbness, psoas weakness (2.2%), sympathetic chain injury (1.3%), cage subsidence (0.9%), and segmental artery injury (0.4%). There was no permanent motor neurological deficit, and no injury of vascular, ureter or peritoneal membranes., Conclusion: The anteroinferior psoas approach for OLIF is safe and can preserve the psoas and lumbar plexus., (© 2021 The Authors. Orthopaedic Surgery published by Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.)

Abstract: Although transforaminal lumbar interbody fusion (TLIF) is a widely accepted procedure, major complications such as cage retropulsion (CR) can cause poor clinical outcomes. Endplate injury (EI) was recently identified as a risk factor for CR, present in most levels developing CR. However, most EIs occurred in non-CR levels, and the features of EIs in CR levels remain unknown.The aim of this study was to identify risk factors for CR following TLIF; in particular, to investigate the relationship between EIs and CR, and to explore the features of EIs in CR.Between October 2010 and December 2016, 1052 patients with various degenerative lumbar spinal diseases underwent bilateral instrumented TLIF. Their medical records, radiological factors, and surgical factors were reviewed and factors affecting the incidence of CR were analyzed.Twenty-one patients developed CR. Nine had back pain or leg pain, of which six required revision surgery. A pear-shaped disc, posterior cage positioning and EI were significantly correlated with CR (P < .001, P = .001, and P < .001, respectively). Computed tomography (CT) scans revealed the characteristics of EIs in levels with and without CR. The majority of CR levels with EIs exhibited apparent compression damage in the posterior part of cranial endplate on the decompressed side (17/18), accompanied by caudal EIs isolated in the central portion. However, in the control group, the cranial EIs involving the posterior part was only found in four of the total 148 levels (P < .001). Most of the injuries were confined to the central portion of the cranial or caudal endplate or both endplates (35 in 148 levels, 23.6%). Additionally, beyond cage breaching into the cortical endplate on lateral radiographs, a characteristic appearance of coronal cage misalignment was found on AP radiographs in CR levels with EIs.A pear-shaped disc, posterior cage positioning and EI were identified as risk factors for CR. EI involving the posterior epiphyseal rim had influence on the development of CR. Targeted protection of the posterior margin of adjacent endplates, careful evaluation of intraoperative radiographs, and timely remedial measures may help to reduce the risks of CR., Competing Interests: The authors have no conflict of interest to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

Objective: Surgery is indicated when antibiotic treatment fails in pyogenic spondylodiscitis, which is caused by pathogens such as the Staphylococcus species. The aim of the present study was to investigate the efficacy and safety of the oblique lateral interbody fusion (OLIF) corridor approach combined with posterior pedicle screw fixation for treating pyogenic spondylodiscitis., Methods: This was a retrospective case series study. A total of 11 patients with an average age of 60.7 years (range, 40-70 years; 10 males and 1 females) with lumbar pyogenic spondylodiscitis who underwent single-stage debridement and reconstruction using the OLIF corridor combined with posterior pedicle screw fixation were recruited in our study from June 2016 to July 2017. All patients had single-level pyogenic spondylodiscitis between T 12 and L 5 . The baseline data, perioperative outcomes (operative time, intra-operative blood loss, and intra-operative complication), postoperative laboratory tests (erythrocyte sedimentation rate [ESR], C-reactive protein [CRP], white blood count [WBC], and tissue culture results), long-term complications (recurrence, fixation failure, and bony non-fusion rates), and duration of antibiotic administration were reviewed. Outcomes evaluated using a variety of scales including visual analog scale (VAS) score and Oswestry disability index (ODI), were compared pre-operatively and post-operatively., Results: The mean follow-up period of time was 18.3 months. The average operative time and intra-operative blood loss were 217.0 ± 91.91 min and 220.9 ± 166.10 mL, respectively. There were no intra-operative complications, except in 1 patient who encountered somatosensory evoked potentials changes and 1 patient who had motor evoked potentials changes, both without post-surgery neurological deficits. Causative organisms were identified in 4 patients: Staphylococcus aureus in 1 patient and Streptococcus in 3 patients. At approximately 8.8 weeks after surgery, WBC, CRP, and ESR had returned to normal levels. All patients were pain free with no recurring infection. There was no fixation failure during follow up. Solid bony fusions were observed in all cases within 6 months. At the final follow up, the mean VAS (0.6 ± 0.69) and ODI (14.4 ± 4.27) were significantly lower than those before surgery (P < 0.05)., Conclusion: One-stage debridement with autogenous iliac bone graft through the OLIF corridor combined with posterior pedicle screw fixation is effective and safe for single-level spontaneous lumbar pyogenic spondylodiscitis after antibiotic treatment fails., (© 2019 The Authors. Orthopaedic Surgery published by Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.)

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., (© 2018 Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.)

Purpose: To evaluate the effect of pure muscle retraction on multifidus injury and atrophy., Materials and Methods: Sixty-three adult New Zealand white rabbits were divided evenly into three groups: 1-h retraction (group R1), 2-h retraction (R2), and sham surgery (C). The multifidus muscle was evaluated using magnetic resonance imaging (MRI) and histology after 3 and 48 h, and 1, 3, 6, 12, and 24 weeks after surgery., Results: Multifidus muscle injury and atrophy were not observed in group C, but were obvious in groups R1 and R2. Edema, necrosis, and inflammation mainly occurred in the first week postoperatively, and were more severe in R2 than in R1 (P < 0.01). Muscle fiber regeneration began at week 1, fibrotic changes mainly occurred at weeks 3 and 6, and fat degeneration became obvious at weeks 12 and 24 postoperatively. The fibrosis and fat degeneration scores of R2 were higher than those of R1 (P < 0.01). Decreased acetylcholine activity and granular degeneration of the neuromuscular junction were observed in both retraction groups, but was more severe in R2 than in R1 (P < 0.01)., Conclusion: Muscle retraction was an important factor not only for multifidus injury, but also for long-term multifidus atrophy after posterior lumbar surgery; a longer retraction time caused more severe multifidus injury and atrophy. Muscle fibers can be regenerated postoperatively, and denervation might be the reason for muscle atrophy.

This cross-sectional study was designed to obtain the current prevalence of deep vein thrombosis (DVT) and analyze related risk factors in patients undergoing lumbar interbody fusion. Medical record data were collected from Department of Spinal Surgery, The Third Hospital of Hebei Medical University, between July 2014 and March 2015. Both univariate analysis and binary logistic regression analysis were performed to determine risk factors for DVT. A total of 995 patients were admitted into this study, including 484 men and 511 women, aged from 14 to 89 years old (median 50, IQR 19). The detection rate of lower limb DVT by ultrasonography was 22.4% (223/995) in patients undergoing lumbar interbody fusion. Notably, average VAS (visual analog scale) score in the first 3 days after surgery in the DVT group was more than that in the non-DVT group (Z = -21.69, P < 0.001). The logistic regression model was established as logit P = -13.257 + 0.056*X1 - 0.243*X8 + 2.085*X10 + 0.001*X12, (X1 = age; X8 = HDL; X10 = VAS; X12 = blood transfusion; x = 677.763, P < 0.001). In conclusion, advanced age, high postoperative VAS scores, and blood transfusion were risk factors for postoperative lower limb DVT. As well, the logistic regression model may contribute to an early evaluation postoperatively to ascertain the risk of lower limb DVT in patients undergoing lumbar interbody fusion surgery.

Study Design: A transcriptional expression assessment of human samples., Objective: To evaluate 12 new candidate nucleus pulposus (NP) markers in degenerative disc disease in a Chinese population., Summary of Background Data: Disc degeneration is a major contributor of low back pain. However, no specific and reliable markers of degeneration of NP are available., Methods: Specimens of NP were collected from 81 patients and grouped into the degenerated disc group (undergoing discectomy and fusion with significant signs of disc degeneration) and the trauma control group (undergoing anterior vertebral body and disc excision and fusion without signs of disc degeneration). Lumbar spine magnetic resonance imaging, hematoxylin-eosin staining, and safranin O staining of sections of NP tissues were conducted to evaluate the severity of the disc degeneration in all samples. Quantitative reverse transcription polymerase chain reaction was performed to investigate the levels of mRNA expression of these genes, as well as those of aggrecan, type II collagen, and SRY-box 9 (SOX-9). Degenerated samples were also divided into groups according to Pfirrmann grading system to elucidate the association of severity of degeneration and gene transcriptional levels. We also tested the relationship between mRNA levels of these genes and clinical characteristics such as hypertension and diabetes mellitus., Results: We demonstrated that 11 of the 12 candidates showed significant differential expression in degenerated discs. Changes in the expression of these 11 genes were determined to be risk factors in degenerative disc diseases. The expression of neurochondrin (NCDN), keratin 8 (KRT8), and matrix Gla protein (MGP) even showed significant changes among subgroups of patients with degenerative disc disease stratified according to the Pfirrmann grading system. The expression of keratin 18 (KRT18), cadherin 2 (CDH2), synaptosomal-associated protein 25 (SNAP25), KRT8, and NCDN was significantly decreased in patients with hypertension. In contrast, the expression of MGP and cartilage oligomeric matrix protein was significantly upregulated in patients with diabetes mellitus., Conclusion: Overall, we demonstrated the clinical utility of 11 novel NP markers for degenerative disc disease. Among them, the expression of NCDN, KRT8, and MGP may indicate the severity of disc degeneration., Level of Evidence: N/A.

Background: Multifidus muscle injury and atrophy are common after posterior lumbar spine surgery and are associated with low back pain and functional disability. In theory, muscle-splitting and retraction with a self-retaining retractor are considered to be the major surgical factors. The effects and mechanisms of retraction have been well studied, but the exact effect and possible mechanism of injury and atrophy after muscle-splitting still lack experimental evidence., Methods: New Zealand White rabbits were divided into two groups. In group S, through a skin and lumbodorsal fascial incision, the bilateral multifidus muscles were dissected from the osseous structures in the standard fashion, while in group C, only a skin and lumbodorsal fascial incision was made. In each group, the multifidus muscle was evaluated by magnetic resonance imaging (MRI) and by histological analysis at three and forty-eight hours and at one, three, six, twelve, and twenty-four weeks after surgery., Results: In group C, there was no injury or atrophy of the multifidus muscle after surgery. In group S, the mean T2-weighted signal intensity ratios of gross multifidus to psoas on fat-suppressed T2-weighted cross-sectional MRI scans peaked on week 3 and returned to baseline on week 24. Necrosis and inflammation of the multifidus muscle were evident and became more severe at one week. Fibrotic change was mainly seen at three and six weeks after surgery, and fatty degeneration mainly occurred at twelve and twenty-four weeks. Decreased acetylcholine activity and granular degeneration of the neuromuscular junction were observed at all follow-up times, and the numbers of degenerating neuromuscular junctions increased significantly with time after surgery., Conclusions: The splitting approach is an important cause of multifidus muscle injury and atrophy in posterior lumbar spine surgery. Denervation and disuse may be important factors in multifidus muscle atrophy in the splitting approach., Clinical Relevance: This study provides a basis for the prevention of multifidus muscle injury and atrophy after posterior lumbar surgery.

Objective: To evaluate effects of vertebroplasty on restoration of vertebral body height and wedge angle and relief from pain in patients with osteoporotic compression fractures., Methods: A retrospective study of 156 patients (232 levels) who had undergone vertebroplasty was conducted. Treated vertebrae with cleft included 49 patients (49 levels) and that without cleft 107 patients (183 levels). Effects on restoration of vertebral body height and wedge angle, and pain scores between pre- and post-procedure were statistically analyzed by using a paired-sample t test, and Kruskal Wallis test., Results: The height and wedge angle of the fractured vertebral body, and pain score, improved significantly after vertebroplasty. On a vertebra-by-vertebra analysis, the vertebral body height and wedge angle in the cleft group, were statistically significantly better post-procedure (P < 0.01); in the non-cleft group, there was nosignificant improved (P > 0.05). Pain relief was not statistically significant different between the two groups (P > 0.05)., Conclusion: Most patients experienced pain relief after vertebroplasty. After vertebroplasty, the height and wedge angle were significantly improved in the cleft group (p < 0.01), with no significant improvement in the non-cleft group (p > 0.05). Key Points • Vertebra with cleft is attributed to improvement of the spinal deformity • Vertebra without cleft was not associated with improvement of the spinal deformity • Vertebroplasty is an effective treatment strategy for osteoporotic compression fractures.

Object: The authors compared the effectiveness of instrumented posterior lumbar interbody fusion (iPLIF) and instrumented posterolateral fusion (iPLF) for the treatment of low-back pain (LBP) due to degenerative lumbar disease., Methods: Relevant randomized controlled trials (RCTs) and comparative observational studies through December 2009 were identified using a retrieval strategy of sensitive and specific searches. The study design, participant characteristics, interventions, follow-up rate and period, and outcomes were abstracted after the assessment of methodological quality of the trials. Analyses were performed following the method guidelines of the Cochrane Back Review Group., Results: Nine studies were identified-3 RCTs and 6 comparative observational studies. No significant difference was found between the 2 fusion procedures in the global assessment of clinical outcome (OR 1.51, 95% CI 0.71-3.22, p = 0.29) and complication rate (OR 0.55, 95% CI 0.16-1.86, p = 0.34). Both techniques were effective in reducing pain and improving functional disability, as well as restoring intervertebral disc height. Instrumented PLIF was more effective in achieving solid fusion (OR 2.60, 95% CI 1.35-5.00, p = 0.004), a lower reoperation rate (OR 0.20, 95% CI 0.03-1.29, p = 0.09), and better restoration of segmental angle and lumbar lordotic angle than iPLF. There were no significant differences between the fusion methods regarding blood loss (weighted mean difference -179.63, 95% CI -516.42 to 157.15, p = 0.30), and operating time (weighted mean difference 8.03, 95% CI -45.46 to 61.53, p = 0.77)., Conclusions: The authors' analysis provided moderate-quality evidence that iPLIF has the advantages of higher fusion rate and better restoration of spinal alignment over iPLF. No significant differences were identified between iPLIF and iPLF concerning clinical outcome, complication rate, operating time, and blood loss.

Thoracolumbar burst fracture (TLBF) is a common type of spinal injuries and frequently causes spinal cord injury. The frequency of neurological deficits in all TLBF can reach up to 50-60%. The typical TLBF images seen on axial computerized tomography are the bone fragment projected into the spinal canal, which always persuade surgeons that the narrowed canal must compress the neural content and therefore is responsible for neurological deficits, with the corollary that surgical decompression of spinal canal is an essential therapeutic strategy for functional recovery. We hypothesize that in TLBF, traumatic canal stenosis is a predictive factor for neurological dysfunction and the surgical decompression is vital to the recovery of neurological function. After a review of the available evidences, we conclude that spinal canal stenosis is poorly correlated with neurological dysfunction in TLBF, and surgical decompression is not vital to the neurological recovery. Therefore, traumatic canal stenosis should not be an isolated indication for surgical decompression in TLBF., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Objective: To determine differences in paraspinal muscle injury between a modified minimally invasive approach (MMIA) and a traditional operative approach (TOPA) for one-level instrumented posterior lumbar inter-body fusion (PLIF)., Methods: From March 2006 to May 2008, a consecutive series of 91 patients who underwent a one-level instrumented PLIF procedure using one of two different approaches (MMIA in 41 patients and TOPA in 50), and who were operated on by one group of surgeons at a single institution, was studied. The following data were compared between the two groups: surgical time, blood loss, and changes in postoperative serum concentration of creatinine kinase (CK). More than 1 year post operation, low back pain was evaluated by a visual analog scale (VAS) and the Oswestry disability index (ODI). Some patients were also evaluated by MRI to allow comparison of the preoperative and postoperative cross sectional area (CSA) and fat degeneration grades at the operative level., Results: There was no statistically significant difference in surgical time, but blood loss, serum concentration of CK, and scores of the VAS and ODI were markedly less in the MMIA group compared with the TOPA group. In the TOPA group, the postoperative CSA of the multifidus muscles was significantly smaller than it was pre-operatively. In contrast, there was no significant difference between the pre- and post-operative CSA of the multifidus muscles in the MMIA group. There was more fatty infiltration postoperatively than preoperatively in both the TOPA and MMIA groups, the increase in fatty infiltration being greater in the TOPA than in the MMIA group., Conclusion: Compared with TOPA, MMIA can significantly lessen paraspinal muscle injury, and reduce the incidence of low back pain., (© 2010 Tianjin Hospital and Blackwell Publishing Asia Pty Ltd.)

Unlabelled: Modic changes are bone marrow and endplate lesions visible in magnetic resonance imaging (MRI). They are regarded as a part of degenerative disc disease and associated with low back pain. And severe disc degeneration was occurred more in the patients with Modic changes. But there is still no study to analyze the relationship between Modic changes and intervertebral disc degeneration. We hypothesize that Modic changes are the possible causes and promotion of lumbar intervertebral disc degeneration. And there are three possible mechanisms for this hypothesis: a structural cause: Modic changes make cartilaginous material easier in extruded disc herniations, to destroy the structure of intervertebral disc and inhibit the absorption of the disc. A biomechanical cause: Modic changes alter the mechanical loading distribution on disc, to initiate a series of disc disruption and inhibit the self-recovery of the disc. A nutritional cause: Modic changes destroy the vascular architecture in vertebral endplate and block the most important metabolism pathway between vertebrae and disc., Perspectives: (1) Find out procedures to cure Modic changes may be an important breakthrough for disc degenerative disease. (2) Treatment of Modic changes may be a critical step of biotherapy for disc degeneration disease.

Objective: To observe degenerative intervertebral disc and to examine innervation of degenerative discs in the rabbit anular-injury model., Methods: Two different magnitudes of anular injury at 5 mm depth were performed by 11 blade or 16 gauge needle at the L3-L4 or L5-L6 discs in New Zealand white rabbits (n=48, 2.5-3.0 kg). Disc degeneration was evaluated by radiographic, MRI and histological examination at different time points after surgery. To identify nerve ingrowth into disc, two general markers PGP 9.5 and GAP 43, for nerve fibers were examined by immunohistochemistry., Result: Significant decreases in disc height and signal intensity in magnetic resonance imaging were observed in 11 blade group and 16 G puncture group (P<0.01). 16 G puncture group induced slower and more progressive disc degeneration companed with the stab group and control group. At the 12-week time point, nucleus pulposus tissues were extruded and scar tissues formed outside the disc. In stab discs, nerve ingrowth was scattered on the surface of injury site and in the deeper part of the scar tissues, more than 1 mm from the surface. However, in punctured discs, PGP 9.5 and GAP 43-immunoreative fibers were only observed in the outmost part of the scar tissues and superficial area. More nerve fibers were observed in stab group., Conclusion: Innervation may act as a source of discogenic pain which is associated with intervertebral disc degeneration caused by disc anular injury.

Objective: To evaluate the clinical outcomes of minimally invasive posterior lumbar interbody fusion (PLIF) assisted by X-Tube system for the management of degenerative lumbar diseases., Methods: A total of 31 patients, 17 male and 14 female with ages from 38 to 75 (average 54.2 years), underwent minimally invasive PLIF assisted by the X-Tube system from May 2005 to March 2006. The index diagnosis was lumbar spondylolisthesis in 14 cases, spinal stenosis in 8 cases, separation of the posterior ring apophysis in 5 cases, intervertebral space stenosis with disk herniation in 4 cases. Before operation, conservative management for at least 6 months was proved to be failure in all these patients. The operative duration and blood loss were estimated . The changes of postoperative serum level of creatinine kinase was measured as well, and compared with the control group of 31 cases who were managed with traditional open PLIF operation during the same period at our department. The clinical functional outcomes were evaluated according to Oswestry disability questionnaire., Results: The operation lasted for 140-225 min, with a mean duration of (176 +/- 22) min. Blood loss during the operation was 270-750 ml, with a mean of (406 +/- 96) ml. Postoperative serum level of creatinine kinase was obviously lower in minimally invasive PLIF cases than in the open control cases. Although 2 pedicle screws in 2 cases were not in ideal position, there was no nerve root irritation or fixation failure and hence no revision was required. One case with spinal stenosis complained of numbness in the area dominated by left L5 nerve root after operation, but the symptom was relieved within 2 weeks through conservative management. All the 31 patients were followed up for 7-17 months, with a mean duration of 12.2 months. Lumbar radiography, and three-dimensional CT reconstruction in some cases, was performed and revealed solid fusion of the surgical segments half a year after the operation. The average Oswestry scores decreased from preoperative 40.6 +/- 5.1 to 17.4 +/- 6.5 at the first postoperative day and to 9.5 +/- 4.0 at the final follow-up. The outcome of this operation were rated as excellent., Conclusions: Minimally invasive PLIF assisted by X-Tube system has the characteristics of less blood loss, tissue trauma and operative time, quick recovery and bony fusion. The short-term outcomes are excellent.

Objective: To evaluate the feature of experimental endplate fracture in lumbar spine and its related factors., Methods: Nineteen cadaveric lumbar motion segments aged 48 - 77 years were compressed by overload to fracture the endplate and dissected into isolated vertebrae to evaluate feature of their endplate failure. Before and after failure of endplate, radiographic tests were taken on every motion segment. The bone mineral density (BMD), bone mineral content (BMC) of the vertebral body and endplate were tested respectively before endplate fracture., Results: Among 19 motion segments, 16 were fractured and accounted for 84.2% of all and fracture featured as stellate, step, depression and intrusion. Fracture concentrated on the center or anterior of superior endplate of the inferior vertebrae in one motion segment. Failure load of endplate was positively correlated with BMD, BMC of vertebral endplate. Within one vertebral body, the BMD and BMC of its superior endplate was markedly less than that of inferior endplate, on the other hand, the difference of BMD and BMC of endplate around one disc was opposite., Conclusions: Fractures usually concentrate on the center or anterior part of superior endplate of one vertebrae and are hard to be identified by conventional radiographic examination. Failure load of endplate is positively correlated with BMD, BMC of vertebral body and endplate. There might be certain relationship between feature of fracture and severity of disc degeneration.