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Prospective cohort study.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).Nowadays, there is still a controversy regarding whether OLIF is superior to MI-TLIF in the management of degenerative lumbar disease.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.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).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.

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., Preoperative static and dynamic anteroposterior radiograph of the lumbar spine. Mild forward slippage of L4, which manifested as instability in lumbar dynamic position, scoliosis, and degenerative change with osteoporosis.

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 0.05). 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., We presented a modified lateral approach (i.e. anteroinferior psoas exposure under direct vision) for OLIF and found that it is safe and can preserve the psoas and the lumbar plexus.

Background A postoperative discal pseudocyst (PDP) is a cystic lesion that is formed in the operation area of the intervertebral disc, leading to recurrence or even worse symptoms. To our knowledge, to date, there is no research focusing specifically on PDP following percutaneous endoscopic interlaminar discectomy (PEID). Case presentation We present the case of a 27‐year‐old man with L5S1 intervertebral disc herniation who was treated with PEID after failed conservative treatment. His leg pain was relieved immediately but reoccurred on the 40th day. MRI showed a PDP. Because loxoprofen and bedrest were ineffective and the patient was anxious, we performed a cystectomy. The patient's symptoms were significantly relieved, and a 6‐month follow up showed no recurrence both clinically and on MRI. Conclusion A PDP is more likely to form using the interlaminar approach than the transforaminal approach. For patients with mental stress, severe pain, and neurological symptoms, surgery is suggested to remove the cyst. Discectomy cannot be performed when disc degeneration is mild., We present the case of a 27‐year‐old man with L5S1 intervertebral disc herniation who was treated with PEID after failed conservative treatment. His leg pain was relieved immediately but reoccurred on the 40th day. MRI showed a PDP. Because loxoprofen and bed rest were ineffective and the patient was anxious, we performed a cystectomy. The patient's symptoms were significantly relieved, and a 6‐month follow‐up showed no recurrence both clinically and on MRI.

Study design A rat model of multifidus muscles injury and atrophy after posterior lumbar spine surgery. Objective We determined the effect of ascorbic acid (AA) on the postoperative multifidus muscles in rat model. Summary of background data Previous studies show oxidative stress and inflammation are two main molecular mechanisms in multifidus muscle injury and atrophy after posterior lumbar surgery. AA may have a protective effect in postoperative multifidus muscles. Methods Rats were divided into sham surgery, control surgery, and surgery plus AA groups. Multifidus muscles of the control and AA groups were excised from the osseous structures. The muscles were retracted continuously for 2 hours. In the sham and AA groups, AA was administered via oral gavage daily in the first week. In each group, the oxidative stress was evaluated by measuring malondialdehyde (MDA) and Total superoxide dismutase (T-SOD). The inflammation, fat degeneration, or fibrosis of multifidus muscle were evaluated by quantitative real-time polymerase chain reaction (q-PCR), histology, or immunohistochemical analysis. Results T-SOD activity was significantly lower in the control group than that in the AA group in the first week. MDA levels were significantly higher in the AA group. Interleukin-6 and tumor necrosis factor-α in multifidus muscles also showed significant differences when treated with AA. The inflammation score on histology was significantly lower in the AA group postoperatively in the first week. In the long run, marker genes for fibrosis and fat degeneration, and fibrosis and fat degeneration scores, were significantly lower in the AA than the control group on days 14 and 28 postoperatively. Conclusion In conclusion, AA attenuated the oxidative stress and inflammation response in the postoperative multifidus muscles, and remarkable differences were observed from the histological assessment and related marker genes expression. Our results provided important insight into the anti-inflammatory and anti-oxidative effects of AA in the postoperative multifidus muscles. Level of evidence N/A.

Experimental study evaluated magnetic resonance imaging (MRI) and histologic changes in the multifidus muscle after anterior spinal fusion. To determine the effect of spinal fusion on the multifidus muscle in an anterior rabbit model through the use of MRI and histologic evaluation. Retraction and splitting approach are known to be important factors in postoperative injury and atrophy of the multifidus muscle. The effect and possible mechanism of spinal fusion as an independent factor remains unknown. Thirty-six New Zealand white rabbits were divided into two groups. Animals in the fusion group underwent two-level anterior spinal fusion whereas those in the control group underwent similar surgery without spinal fusion. The status of the multifidus muscle was evaluated with MRI and histological analysis at preoperative, 3 weeks, 6 weeks, 3 months, 6 months, and 12 months postoperatively. All rabbits in the fusion group achieved solid fusion. The mean T1-weighted and T2-weighted signal intensity ratios of gross multifidus to psoas muscles were all approximately 1.0 postoperatively, with no remarkable difference between the groups. The mean lesser diameter of myofibrils in either group did not significantly differ between the preoperative and postoperative specimens. There was no significant fibrotic change or fatty degeneration for either group. Decrease in acetylcholine activity or granular degeneration of the neuromuscular junction were not observed, and normal shape and size were found in nearly all samples at all time points in both groups (P > 0.05). After two-segment anterior spinal fusion, multifidus atrophy was not observed throughout a 12-month follow up. The rabbit model of anterior fusion is better suited to study the effect of fusion alone on the status of the multifidus muscle. Level of Evidence: 3

BACKGROUND: Many studies have explored the relationship between facet tropism and facet joint osteoarthritis, disc degeneration and degenerative spondylolisthesis. However, the associations between facet orientation and tropism, and paraspinal muscles have not been studied. OBJECTIVE: To analyze the associations between facet orientation and tropism, and parameters of paraspinal muscles in patients with chronic low back pain. METHODS:Ninety-five patients withchronic low back pain were consecutively enrolled. Their facet joint angles weremeasured on computed tomography (CT) while gross cross-sectional area (GCSA), functional cross-sectional area (FCSA) and T2 signal intensity of lumbar paraspinal and psoas muscle were evaluated on magnetic resonance imaging (MRI). RESULTS: The GCSA and FCSA were significantly smaller for multifidus muscle ( P< 0.001), but significantly larger for erector spinae and psoas muscles ( P< 0.001), in coronally-orientated group than those in sagittally-orientated group. The differences of bilateral GCSA and FCSA of multifidus muscle were significantly larger in facet tropism group than those in no facet tropism group (P = 0.009 and P = 0.019). CONCLUSIONS: Muscular asymmetries may develop in the lumbar region of the spine, which are associated with facet asymmetry in patients with chronic low back pain. Longitudinal studies are needed to understand the causal relationship between facet orientation and tropism and muscular asymmetry in future.

Modic changes are the MRI signal changes of degenerative lumbar vertebral endplate and which lead to or accelerate intervertebral disc degeneration. NLRP3, caspase-1, and interleukin-1β (IL-1β) play a pivotal role in the pathogenesis of many inflammatory diseases, such as osteoarthritis. However, the roles of IL-1β and its activators caspase-1 and NLRP3 are unclear in the degenerative endplate. We asked: (1) What are the degenerative changes of the histologic features and chondrogenic markers’ gene expressions between the cartilaginous endplates of patients with Modic changes and trauma (control)? (2) How does the NLRP3/caspase-1/IL-1β axis in the cartilaginous endplates of patients with Modic changes compare with control (trauma) specimens? Surgical specimens of cartilaginous endplates were divided into Modic changes (n = 56) and the trauma control (n = 16) groups. Hematoxylin and eosin and safranin O staining of cartilaginous endplate tissues were done to evaluate the extracellular matrix. Reverse transcription-polymerase chain reaction was performed on these tissues to investigate mRNA expression of type II collagen (Col II), SOX-9, matrix metalloproteinase-3, and a disintegrin like and metalloproteinase thrombospondin type I motifs-5. NLRP3, caspase-1, and IL-1β were evaluated by reverse transcription-polymerase chain reaction and immunohistochemistry. Hematoxylin and eosin and safranin O staining showed the extracellular matrix degraded in the cartilaginous endplates of patients with Modic changes but not in the control cartilaginous endplates. Chondrogenic Col II (p = 0.024) and SOX9 (p = 0.053) were downregulated in the Modic changes group compared with the control group. In contrast to the control group, the transcriptional levels of NLRP3 (p < 0.001), caspase-1 (p = 0.054), and IL-1β (p = 0.001) were all upregulated in the Modic changes group. The expression of NLRP3, caspase-1, and IL-1β was upregulated in the patients with low back pain and Modic changes on MRI compared with patients with vertebral burst fracture without degenerative changes on MRI. The data suggest the NLRP3/caspase-1/IL-1β axis may be implicated in lumbar cartilaginous endplate degeneration. The NLRP3/caspase-1/IL-1β axis is active in cartilaginous endplates of patients with Modic changes and inflammatory cascades can exacerbate the cartilaginous endplate degeneration which may act as a trigger for intervertebral disc degeneration and low back pain. If these findings can be confirmed by others, we hope that new and effective therapy could be developed directed against this target.

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.

The approach-related morbidity resulting from iatrogenic erector spinae injury in posterior lumbar surgery has become an increasing concern for spine surgeons. Many studies have explained the injury mechanisms and reported new surgical approaches to prevent this iatrogenic injury from their own point of views, but there is still no systemic information for a thorough understanding of this iatrogenic erector spinae injury that may give spine surgeons practical advices in their individual operations. We consequently reviewed the literature on the anatomy of erector spinae, causes of injury, and relative minimally invasive approaches. We found that the local anatomic structures make the erector spinae vulnerable to injury during posterior lumbar surgery, especially the medial multifidus which is innervated only by the medial branch of the dorsal ramus, with no intersegmental nerve supply as in the other paraspinal muscles, and the injury factors mainly include dissection, retraction, denervation, and immobility. Studies suggest that the goal of prevention is to preserve the physiological structure of erector spinae and to avoid or limit the injury causes: approaches through spatium intermusculare and approaches with endoscope and tubular retractor system can prevent the erector spinae from injury by less dissection and retraction; non-fusion techniques may prevent the erector spinae from disuse atrophy by preserving the segmental motion and the adjacent erector spinae activity.

The aim of this study was to evaluate early ASD at short-term follow-up in fused and unoperated patients with degenerative disc disease, using quantitative magnetic resonance imaging (MRI) analysis of the area, signal intensity and their product, i.e., MRI index of the central bright area of the disc as well as measures of intervertebral disc height and Pfirrmann grading scale. The further purpose was to determine whether fusion accelerates ASD compared with non-surgical treatment in short-term follow-up.One hundred and eight chronic low back patients diagnosed as L4/L5 degeneration undertook either one-level instrumented posterior lumbar interbody fusion or conservative treatment. They were followed up for about 1 year. Finally 46 fused and 45 conservatively treated patients with MRI follow-up were included. Pre- and post-treatment MRIs were compared to determine the progression of disc degeneration at the two cranial adjacent segments.The area, signal intensity and MRI index of the central bright area of the adjacent discs decreased in the operated and unoperated groups from pre-treatment to follow-up, except for an insignificant decrease of signal intensity at the second adjacent segment in the unoperated group. The changes in these parameters were statistically greater at the first than the second adjacent segment in the fused group, but not in the unoperated group. And the changes in the fused group were more pronounced than those at both neighbouring levels in the unoperated group. However, the Pfirrmann grading scale and intervertebral disc height did not detect any changes at adjacent discs in either group.Decrease in the parameters of quantitative MRI analysis indicated early degeneration at discs adjacent to lumbar spinal fusion. Fusion had an independent effect on the natural history of ASD during short-term follow-up. Continued longitudinal follow-up is required to determine whether these MRI changes lead to pathologic changes.

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.

We set out to determine whether a minimally invasive approach for one-level instrumented posterior lumbar interbody fusion reduced undesirable changes in the multifidus muscle, compared to a conventional open approach. We also investigated associations between muscle injury during surgery (creatinine kinase levels), clinical outcome and changes in the multifidus at follow-up. We studied 59 patients treated by one team of surgeons at a single institution (minimally invasive approach in 28 and conventional open approach in 31, voluntarily chosen by patients). More than 1 year postoperatively, all the patients were followed up with the visual analogue scale (VAS) and Oswestry disability index (ODI), and 16 patients from each group were evaluated using MRI. This enabled the cross-sectional area (CSA) of lean multifidus muscle, and the T2 signal intensity ratio of multifidus to psoas muscle, to be compared at the operative and adjacent levels. The minimally invasive group had less postoperative back pain (P

Study design This study investigated the expression of 2 types of ADAMTS in human intervertebral cartilage endplate (CEP) and related mechanisms concerning tumor necrosis factor α (TNF-α)-induced nuclear factor κB signaling pathway. Objective To determine which type of ADAMTS is more strongly expressed and the role of TNF-α in CEP. Summary of background data ADAMTS-4 and ADAMTS-5 were proven to be essential in the degeneration of articular cartilage and intervertebral disc. CEP is an important structure adjacent to the disc. However, the activities of ADAMTS in CEP are unclear. Methods CEPs were obtained from subjects after spinal surgery and categorized as members of either the Modic change group or the control group. Sections of these tissues were stained with hematoxylin-eosin, safranin O, and immunohistochemistry procedures for ADAMTS-4, ADAMTS-5, and TNF-α. Transcriptional levels of aggrecan, type I collagen, type II collagen, type X collagen, ADAMTS-4, ADAMTS-5, and TNF-α were investigated by quantitative real-time polymerase chain reaction. In addition, the effect of TNF-α on ADAMTS-5 and its potential mechanisms are investigated in cultured bovine endplate chondrocytes in vitro. Results Our data demonstrated that the degenerative changes associated with the expression of extracellular matrix proteins were correlated with increased levels of ADAMTS-5, but not ADAMTS-4, in the CEP of patients with Modic changes. The expression levels of TNF-α in the Modic change group were significantly increased, which was correlated with the enhanced expression of ADAMTS-5. Additional in vitro investigation confirmed that TNF-α could upregulate the expression of ADAMTS-5 by activating nuclear factor κB pathway in cultured bovine endplate chondrocytes. Conclusion We conclude that the upregulation of TNF-α and ADAMTS-5, but not ADAMTS-4, may play an important role in degenerative CEP-induced low back pain. Level of evidence N/A.

To study differences of multifidus muscle injury between Wiltse intermuscular approach and intramuscular stripping approach in one-level small incision transforaminal lumbar interbody fusion (TLIF) surgery.A total of 46 patients with unilateral lumbar degenerative disease underwent small incision TLIF from August 2009 to February 2011 by one group of surgeons at a single institution. The decompression side of all patients adopted intra-muscular stripping approach; for the non-decompression side, 22 patients adopted Wiltse intermuscular approach (group A),and 24 patients adopted intra-muscular striping approach (group B). In group A, there were 13 males and 9 females, ranging in age from 36 to 74 years old,averaged 52.7 +/- 9.2; 1 patient had disease in L3, 4 12 in L4,5 and 9 in L5S1. In group B,there were 11 males and 13 females,ranging in age from 32 tio 72 years old, averaged 51.8 +/- 8.7; two patients had disease in L3,4, 14 in L4,5, and 8 in L5S1. The following data were compared between the 2 groups: surgical time from skin incision to completion of pedicle screw placement, suturation time, blood loss. Clinical effects were evaluated by VAS score pre-operatively, as well as 1, 6 and 12 months post-operatively. At the latest follow-up, all the patients were evaluated by MRI. This enabled the cross-sectional area (CSA) of lean multifidus muscle, and the T2 signal intensity ratio of multifidus to psoas muscle, to be compared at the operative level.There was no obvious difference in suturation time, but less surgical time from skin incision to completion of pedicle screw placement, less blood loss, less postoperative back pain in Wiltse intermuscular approach group. For the comparison between the two groups or paired comparison between sides in the Wiltse group, the reduction of lean CSA and increase in the multifidus:psoas T2 signal intensity ratio were all significant lower in Wiltse intermuscular approach group or side.The Wiltse intermuscular approach is an easy way for pedicle screw placement, and caused less paraspinal muscle damage than intra-muscular stripping approach, and had positive effects on less back pain.

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.

Summary 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.