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Objectives: Test the odds of factors previously associated with lower limb injury (decreased size of the multifidus (MF) and increased size of the quadratus lumborum (QL) muscle) in an independent sample of Australian Rules Football (ARF) players., Design: Prospective cohort study., Setting: Professional ARF., Participants: Forty-three male ARF players., Main Outcome Measures: Cross-sectional areas (CSAs) of MF and QL muscles measured from pre-season ultrasound images. Playing season injuries were recorded by club personnel. A multivariable logistic regression model was used to evaluate the usefulness of MF and QL muscle size for predicting playing season lower limb injuries., Results: Fifteen players (35%) sustained a playing season lower limb injury. The multivariable model indicated that the odds of sustaining a lower limb injury during the season was 2.38 (95% CI: 1.18, 5.00; P = 0.017) times less likely for a one cm 2 increase from the mean value in MF muscle CSA at the L5 vertebral level after adjusting for CSA of the QL, age and BMI. The main effect and interaction models positively predicted 75% of players that sustained a lower limb injury during the season (sensitivity 80%, specificity 85%)., Conclusion: Future studies could examine the efficacy, feasibility and adherence of 'at risk' players to a pre-season training program aimed at increasing MF muscle size and monitor playing season injuries., Competing Interests: Declaration of competing interest None declared., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Context: A smaller lumbar multifidus (LM) muscle was reported to be a strong predictor of lower limb injury in professional Australian Football League players. However, despite the high prevalence of low back pain (LBP) and lower limb injury in rugby players, their LM characteristics have yet to be explored., Objective: To (1) examine LM characteristics in male and female university rugby players and their possible associations with LBP and lower limb injury and (2) investigate the relationship between LM characteristics and body composition in this group of athletes., Design: Cross-sectional study., Setting: University research center., Patients or Other Participants: Thirty-four university rugby players (20 women, 14 men)., Main Outcome Measure(s): Ultrasound measurements of LM cross-sectional area (CSA), thickness, and percentage change in thickness during contraction were obtained bilaterally, at the L5-S1 level, in prone and standing positions. Body composition measures were obtained using dual-energy x-ray absorptiometry. Self-reported questionnaires were used to obtain LBP and lower limb injury history., Results: Players who reported LBP in the previous 3 months showed a smaller percentage change in thickness during contraction in the standing position (F = 5.21, P = .03). The LM CSA side-to-side asymmetry (right versus left) was greater in players who reported having a lower limb injury in the previous 12 months (F = 4.98, P = .03). The LM CSA was significantly associated with body composition measurements. A greater percentage change in thickness during contraction was significantly associated with a lower percentage of body fat. The LM echo intensity was strongly associated with the total percentage of body fat and was significantly greater in women., Conclusions: The influence of body composition on LM morphology in athletes cannot be ignored and warrants further investigation. Our findings also provide preliminary evidence of an association among LM morphology, LBP, and lower limb injury in university rugby players., (© by the National Athletic Trainers' Association, Inc.)

Background: To compare standalone oblique lateral interbody fusion (OLIF) vs. OLIF combined with posterior bilateral percutaneous pedicle screw fixation (OLIF combined) for the treatment of lumbar spondylolisthesis., Methods: This was a retrospective study of patients who underwent standalone OLIF or combined OLIF between 07/2014 and 08/2017 at two hospitals in China. Direct decompressions were not performed. Visual analog scale (VAS), Oswestry Disability Index (ODI), satisfaction rate, anterior/posterior disc heights (DH), foraminal height (FH), foraminal width (FW), cage subsidence, cage retropulsion, fusion rate, and complications were analyzed. All imaging examinations were read independently by two physicians and the mean measurements were used for analysis., Results: A total of 73 patients were included: 32 with standalone OLIF and 41 with combined OLIF. The total complication rate was 25.0% with standalone OLIF and 26.8% with combined OLIF. There were no differences in VAS and ODI scores by 2 years of follow-up, but the scores were better with standalone OLIF at 1 week and 3 months (P < 0.05). PDH and FW was smaller in the combined OLIF group compared with the standalone OLIF group before and after surgery (all P < 0.05). There were significant differences in FH before surgery and at 1 week and 3 months between the two groups (all P < 0.05), but the difference disappeared by 2 years (P = 0.111). Cage subsidence occurred in 7.3% (3/41) and 7.3% (3/41) of the patients at 3 and 24 months, respectively, in the combined OLIF group, compared with 6.3% (2/32) and 15.6% (5/32), respectively, in the standalone OLIF group at the same time points (P = 0.287). There was no cage retropulsion in both groups at 2 years. The fusion rate was 85.4%(35/41) in the combined OLIF group and 84.4% (27/32) in the standalone OLIF group at 3 months(P = 0.669). At 24 months, the fusion rate was 100.0% in the combined OLIF group and 93.8% (30/32) in the standalone OLIF group (P = 0.066)., Conclusion: Standalone OLIF may achieve equivalent clinical and radiological outcomes than OLIF combined with fixation for spondylolisthesis. The rate of complications was similar between the two groups. Patients who are osteoporotic might be better undergoing combined rather than standalone OLIF. The possibilty of proof lies within a future prospective study, preferably an RCT.

Background: There is no available literature for comparison on muscle atrophy between the "stand-alone" oblique lateral interbody fusion (OLIF) and regular OLIF (i.e., combined with percutaneous pedicle screws fixation (PPSF) in patients with spondylolisthesis). This study aimed to identify changes in back muscle atrophy between the two surgeries., Methods: This was a retrospective cohort study of patients who underwent OLIF or OLIF+PPSF at Beijing Jishuitan Hospital and Shanghai ChangZheng Hospital between 07/2014 and 10/2017. Computed tomography (CT) was used to measure functional cross-sectional area (FCSA) and fat infiltration percentage (FIP) of the multifidus and erector spinae before and 24 months after surgery., Result: There were no differences in FCSA and FIP between OLIF (n = 32) and OLIF+PPSF (n = 41) groups before surgery. In the OLIF group, the multifidus and erector spinae FCSA and FIP did not change at 24 months (FCSA: multifidus: from 8.59 ± 1.76 to 9.39 ± 1.74 cm 2 , P = 0.072; erector spinae: from 13.32 ± 1.59 to 13.55 ± 1.31 cm 2 , P = 0.533) (FIP: multifidus: from 15.91 ± 5.30% to 14.38 ± 3.21%, P = 0.721; erector spinae: from 11.63 ± 3.05% to 11.22 ± 3.12%, P = 0.578). In the OLIF+PPSF group, the multifidus and erector spinae FCSA decreased (multifidus: from 7.72 ± 2.69 to 5.67 ± 1.71 cm 2 , P < 0.001; erector spinae: from 12.60 ± 2.04 to 10.15 ± 1.82 cm 2 , P < 0.001), while the FIP increased (multifidus: from 16.13 ± 7.01% to 49.38 ± 20.54%, P < 0.001; erector spinae: from 11.93 ± 3.22% to 22.60 ± 4.99%, P < 0.001). The differences of FCSA and FIP between the two groups at 24 months were significant (all P < 0.001). The patients in the standalone OLIF group had better VAS back pain, and JOA scores than the patients in the OLIF combined group (all P < 0.05) at 1 week and 3 months after surgery. There were two cases (4.9%) of adjacent segment degeneration in the OLIF combined group, while there was no case in the OLIF alone group., Conclusions: Standalone OLIF had better clinical outcomes at 1 week and 3 months than OLIF+PPSF in patients with spondylolisthesis. OLIF may not result in paraspinal muscle atrophy at 24 months after surgery.

Muscle injuries are very common in sports medicine, but involvement of the paraspinal muscles is relatively rare. The diagnosis is usually clinical, but diagnostic imaging modalities (ie, ultrasound and magnetic resonance) identify, in detail, the anatomical site and extension of the lesion helping the physician plan a specific rehabilitation program. Likewise, the authors present an unusual case of a amateur volleyball player who suffered injury of the paraspinal muscles after a session of manual therapy with deep massage. The authors also highlight the potential role of ultrasound imaging in detecting muscle injuries not only in the limbs but also at the level of paraspinal region for prompt management and return to play.

Introduction: Proximal junctional kyphosis - PJK has been defined by a 10 or greater increase in kyphosis at the proximal junction as measured by the Cobb angle from the caudal endplate of the uppermost instrumented vertebrae (UIV) to the cephalad endplate of the vertebrae 1 segments cranial to the UIV. In this biomechanical study, it is aimed to evaluate effects of interspinosus ligament complex distruption and facet joint degeneration on PJK development., Materials and Methods: Posterior instrumentation applied between T2 - T7 vertebrae using pedicle screws to randomly selected 21 sheeps, divided into 3 groups. First group selected as control group (CG), of which posterior soft tissue and facet joints are protected. In second group (spinosus group, SG) interspinosus ligament complex which 1 segment cranial to UIV has been transected, and third group (faset group-FG) was applied facet joint excision. 25 N, 50 N, 100 N, 150 N and 200 N forces applied at frequency of 5 Hertz as 100 cycles axial to the samples. Then, 250 N, 275 N and 300 N forces applied static axially. Interspinosus distance, kyphosis angle and discus heights was measured in radiological evaluation. Abnormal PJK was defined by a proximal junctional angle greater than 10 0 and at least 10 0 greater than the corresponding preoperative measurement., Results: In CG group, average interspinosus distance was 6,6 ± 1.54 mm and kyphosis angle was 2,2 ± 0.46° before biomechanical testing, and they were measured as 9,4 ± 1.21 mm and 3,3 ±0.44° respectively after forces applied to samples. In SG group, average interspinosus distance was 6,2 ± 1.72 mm and kyphosis angle was 2,7 ± 1.01° before experiment, and they were measured as 20,8 ± 5.66 mm and 15,1 ± 2.34° respectively after forces applied to samples. In FG group, average interspinosus distance was 4,8 ± 1.15 mm and kyphosis angle was -1 ± 4.14° before experiment, and they were measured as 11,1 ±1.96mm and 11 ± 2.87° respectively after forces applied to samples. In comparison to group CG, statistically significant junctional kyphosis was seen on both FG and SG group after statistical analysis. (p < 0.05). PJK was seen statistically significant more on SG group than FG group. (p < 0.05). Not any statistically significant difference was seen on measurement of disk distances among three groups. (p > 0.05) CONCLUSIONS: Protecting interspinosus ligament complex and facet joint unity during posterior surgical treatment for spine deformation is vital to prevent PJK development. Based on our literature review, this is the first biomechanical study that reveals interspinosus ligament complex are more effective on preventing PJK development than facet joints., (Copyright © 2019 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.)

Background: Compartment syndrome is a life-threatening complication of traumatic injury, most commonly, direct trauma. Back pain is a common cause of visits to the emergency department (ED) and often is treated without imaging or diagnostic testing. Lumbar paraspinal compartment syndrome is a rare cause of acute back pain., Case Report: A 43-year-old woman presented to the ED after direct trauma to the lower back. Laboratory studies revealed rhabdomyolysis and acute kidney injury, with examination findings and imaging consistent with lumbar paraspinal compartment syndrome. She was taken to the operating room for emergent fasciotomy. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: It is the job of the emergency physician to identify the red flags in history and physical examination that warrant further diagnostic testing. Early diagnosis and surgical consultation is the key in avoiding morbidity and achieving good outcomes in all forms of compartment syndrome., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Introduction: The relationship of hip range of motion (ROM) to shoulder, elbow, abdominal, and back injuries remains undefined., Methods: We assessed hip ROM on players reporting to Major League Spring Training for an organization over six seasons (2010 to 2015). Hip ROM was correlated with player abdominal, back, shoulder, and elbow injury status for those seasons using multivariate binomial logistic regression analysis., Results: A total of 258 player-seasons (129 pitchers and 129 position players) resulted in 20 back and 35 abdominal injuries across all players and 28 elbow and 25 shoulder injuries in pitchers. Hip ROM did not correlate with shoulder or elbow injuries. Hip internal rotation deficit of 5° correlated with core injury (odds ratio [OR], 1.40; P = 0.024 for pitchers; OR, 1.35; P = 0.026 for position players) and back injury (OR, 1.160; P = 0.022 for pitchers)., Discussion: Hip internal rotation deficits were predictive of back and abdominal injuries but not shoulder or elbow injury.

Dental injection needle breakage is an uncommon problem in dental practice. Displacement of the broken fragment into anatomical spaces is, on the other hand, a serious complication that occurs most commonly during inferior alveolar nerve blocks as a result of material wear, incorrect application of the anesthesia technique, or sudden movement of the patient during injection. Further complications such as infection, trismus, and nerve paralysis may exacerbate the condition and, if not treated adequately, life-threatening conditions may develop over time as the fragment dislodges deeper in soft tissues. Clinical symptoms of the patient, as well as the findings gathered from detailed physical examination and radiographic evaluation, are important factors to consider before performing an exploratory surgery. Removal of a broken needle may be troublesome due to its proximity to vital anatomic structures. Multislice computed tomography is a reliable imaging modality that provides accurate information to pinpoint the exact location of the needle fragment.This report describes a case of needle breakage occurred during inferior alveolar nerve block which was performed to extract a third molar tooth and the migration of the broken fragment from the right mandibular ramus area into the perivertebral space, with special emphasis on the surgical retrieval technique with multiplanar computed tomography imaging guidance.

Objective: To compare the clinical effects and multifidus muscle injury of different approaches, including unilateral Wiltse intermuscular approach and intramuscular approach combined with contralateral decompression, in treating thoracolumbar burst fracture., Methods: Forty-three patients with thoracolumbar burst fracture were enrolled in the study from January 2010 to December 2014, including 29 males and 14 females with an average age of 42.3 years old(ranged from 21 to 64 years old). The patients were treated with posterior pedicle screw fixation and unilateral decompression and were divided into Wiltse intermuscular approach group (group A) and intramuscular approach group (group B) according to surgical approach. Operation time and intraoperative bleeding were recorded for all patients; visual analogue scale(VAS) was compared 1 d preoperatively, 1 week, 12 months postoperatively between two groups; preoperation and 12 months postoperatively, the fractured vertebral canal and two-sides multifidus muscle of the same section were observed and compared by CT measure between two groups., Results: All the patients were follow-up for 14 to 21 months with an average of 16.3 months. Partial wound non-healing occurred in 3 patients and the wound ultimately healing after debridgement suture and change dressings. No screw breakage was found. There was significant difference in operation and intraoperative bleeding operation between two groups ( P <0.05), while there was no significant difference in VAS score of 1 d preoperatively, 1 week, 12 months postoperatively between two groups( P >0.05). As for CT measurement results, postoperative vertebral canal narrow ratio was significant decreased in all patients( P <0.05), while perioperative changes of the two-sides multifidus muscle cross section area and density were significant in group A ( P <0.05), but there was no significant difference in group B ( P >0.05). Neurologic status of all patients got recovery at final follow-up., Conclusions: The method of unilateral Wiltse intermuscular approach combined with contralateral decompression for the treatment of thoracolumbar burst fracture has good clinical effects, also it is less invasive and less damage to multifidus muscle compared with intramuscular approach., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose.

Background: Posterior lumbar surgery can lead to damage on paraspinal muscles., Objective: Our study aimed to examine the recovery in the denervated paraspinal muscles by posterior lumbar surgery and to determine that of improvement in the lower back pain (LBP)., Methods: Depending on surgical treatments, the patients were divided into two groups: The group I (interspinous implantation with decompression) and II (posterior lumbar interbody fusion with decompression). The paraspinal mapping score was recorded for individual muscle., Results: In the group I, there was reinnervation in the denervated multifidus and erector spinae at the upper, surgical and lower levels at 12 months. In the group II, there was reinnervation in the denervated erector spinae at the upper, surgical and lower levels at 12 months. There was significant aggravation in the LBP in both groups at immediate postoperative. But there was significant improvement in it at 6 months in the group I and at 12 months in the group II., Conclusion: There was reinnervation in not only denervated multifidus and erector spinae at 12 months following interspinous ligament stabilization but also in denervated erector spinae at 12 months following pedicle screw fixation with fusion.

Purpose: It is well established that posterior spinal surgery results in damage to the paraspinal musculature. The effects of such iatrogenic changes on spinal loading have not been previously investigated, particularly at levels adjacent to a spinal fusion. Therefore, the objective of this study was to investigate the effect of simulated muscle damage on post-operative spinal loading at the adjacent levels to a spinal fusion during upright postures using a mathematical model., Methods: A musculoskeletal model of the spine using ArtiSynth with 210 muscle fascicles was used to predict spinal loading in an upright posture. The loading at L1-L2 and L5-S1 were estimated before and after simulated paraspinal muscle damage (i.e., removal of muscle attachments at L2-L5) along the lumbar spine, both with a spinal fusion at L2-L5 and without a spinal fusion., Results: The axial compressive forces at the adjacent levels increased after simulated muscle damage, with the largest changes being at the rostral level (78 % increase in presence of spinal fusion; 73 % increase without spinal fusion) compared to the caudal level (41 % in presence of fusion and 32 % without fusion). Shear forces increased in a similar manner at both the rostral and caudal levels. These changes in loading were due to a redistribution of muscle activity from the local lumbar to the global spinal musculature., Conclusions: The results suggest that the paraspinal muscles of the lumbar spine play an important role in adjacent segment loading of a spinal fusion, independent of the presence of rigid spinal instrumentation.

We aimed to describe the surgical technique and clinical outcomes of paraspinal-approach reduction and fixation (PARF) in a group of patients with Denis type B thoracolumbar burst fracture (TLBF) with neurological deficiencies. A total of 62 patients with Denis B TLBF with neurological deficiencies were included in this study between January 2009 and December 2011. Clinical evaluations including the Frankel scale, pain visual analog scale (VAS) and radiological assessment (CT scans for fragment reduction and X-ray for the Cobb angle, adjacent superior and inferior intervertebral disc height, and vertebral canal diameter) were performed preoperatively and at 3 days, 6 months, and 1 and 2 years postoperatively. All patients underwent successful PARF, and were followed-up for at least 2 years. Average surgical time, blood loss and incision length were recorded. The sagittal vertebral canal diameter was significantly enlarged. The canal stenosis index was also improved. Kyphosis was corrected and remained at 8.6±1.4o (P>0.05) 1 year postoperatively. Adjacent disc heights remained constant. Average Frankel grades were significantly improved at the end of follow-up. All 62 patients were neurologically assessed. Pain scores decreased at 6 months postoperatively, compared to before surgery (P<0.05). PARF provided excellent reduction for traumatic segmental kyphosis, and resulted in significant spinal canal clearance, which restored and maintained the vertebral body height of patients with Denis B TLBF with neurological deficits.

Study Design: Observational diagnostic study on consecutive patients., Objective: To assess the efficacy of magnetic resonance imaging (MRI) for detecting spinal soft tissue injury after acute trauma using intraoperative findings as a reference standard., Summary of Background Data: Recognizing injuries to spinal soft tissue structures is critical for proper decision making and management for blunt trauma victims. Although MRI is considered the gold standard for imaging of soft tissues, its ability to identify specific components of soft tissue damage in acute spine trauma patients is poorly documented and controversial., Methods: Intraoperative findings were recorded for 21 acute spinal trauma patients (study group) and 14 nontraumatic spinal surgery patients (control group). Preoperative MRI's were evaluated randomly and blindly by 2 neuroradiologists. MRI and intraoperative findings were compared. By using the intraoperative findings as the reference standard, sensitivity, specificity, positive and negative predictive values of MRI in detecting spinal soft tissue injury were determined., Results: MRI was 100% sensitive and specific in detecting injury to the anterior longitudinal ligament. MRI was moderately sensitive (80%) but highly specific (100%) for injury to the posterior longitudinal ligament. In contrast, MRI was highly sensitive but less specific in detecting injury to paraspinal muscles (100%, 77%), intervertebral disk (100%, 71%), and interspinous ligament (100%, 64%). MRI was moderately sensitive and specific in detecting ligamentum flavum injury (80% and 86.7%) but poorly sensitive for facet capsule injury (62.5%)., Conclusions: MRI demonstrated high sensitivity for spinal soft tissue injuries. However, MRI showed a definite trend to overestimate interspinous ligament, intervertebral disk, and paraspinal muscle injuries. On the basis of these results, we would consider MRI to be a useful tool for spine clearance after trauma. Conversely, caution should be applied when using MRI for operative decision making due to its less predictable specificity.

Purpose: To confirm the validity of postoperative creatine kinase (CK) values as an indicator of muscle lesion, assess the relationship of CK with variables indicating surgical invasiveness and investigate an association between CK values and excessive postoperative pain., Material and Methods: The study included 96 patients (mean age 62.8 years) who underwent instrumented spine fusion for degenerative lumbosacral disease. Serum CK concentration was determined on the first postoperative day. All patients received intravenous paracetamol and metamizole, and in cases of intense pain, rescue analgesia with iv meperidine. Patients were categorized according to whether or not they required rescue analgesia. Data on the number of levels fused, the duration of surgery, and operative bleeding were recorded in each patient., Results: CK values were higher in men and in younger patients. Significant correlations were found between CK and the number of fused levels and duration of surgery. Only 17.7% of patients required rescue analgesia. CK levels did not significantly differ between patients who did not need rescue analgesia (1135 IU/L) and those who did (1421.5 IU/L)., Conclusions: Serum CK concentration is a valid marker of surgical muscle injury and is affected by the age and sex. Factors such as the magnitude and duration of surgery show a relationship with postoperative CK values. The incidence of severe postoperative pain is not significantly related to CK level.

Study Design: A matched-pairs animal study., Objective: To confirm the accuracy of magnetic resonance imaging (MRI) as a means of evaluating edema and fat degeneration of the multifidus muscle by comparing measurements made using MRI with those made using histological examination., Summary of Background Data: MRI is considered a reliable means of evaluating multifidus muscle edema and fat degeneration. However, it is not clear whether its results are always consistent with histological findings., Methods: Models of different degrees of multifidus injury were created at the L2-L3, L3-L4, and L4-L5 disc levels in 56 New Zealand white rabbits. These were divided into 4 groups and subjected to different processes: sham surgery, dissection and stripping of the multifidus, crushing of the muscle lasting 1 hour, and crushing of the muscle lasting 2 hours. Two rabbits per group were examined at each of the indicated points in time. Multifidus edema was assessed using fat-suppressed T2 signal intensity ratio of gross multifidus to psoas (T2R) on MRI bilaterally, wet weight and wet:dry weight ratio on the left side (edema-left), and visual edema score on the right side (edema-right). Muscle fat degeneration was detected bilaterally using the T1 signal intensity ratio of gross multifidus to psoas with MRI (T1R) and visual fat degeneration score (fat score) with histology., Results: Pearson correlation coefficient analyses showed significant correlations (P < 0.001) between left T2R and edema-left (r = 0.927), right T2R and edema-right (r = 0.868), and T1R and fat score (r = 0.804). A paired t test demonstrated no significant differences between MRI measurements and histological changes (P = 0.999, 1.000, and 0.998). Bland-Altman plots also depicted good agreement between MRI measurements and histological changes (limits of agreement: left multifidus edema, ± 0.75; right multifidus edema, ± 1.01; fat degeneration, ± 1.23)., Conclusion: The MRI technique is an accuracy means of evaluating multifidus muscle injury and atrophy.

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.

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 review the latest comparative research of minimally invasive transforaminal lumbar interbody fusion (TLIF) and traditional open approach., Methods: The domestic and foreign literature concerning the comparative research of minimally invasive TLIF and traditional open TLIF was reviewed, then intraoperative indicators, length of hospitalization, effectiveness, complication, fusion rate, and the effect on paraspinal muscles were analyzed respectively., Results: Minimally invasive TLIF has less blood loss and shorter length of hospitalization, but with longer operation and fluoroscopic time. Minimally invasive surgery has the same high fusion rate as open surgery, however, its effectiveness is not superior to open surgery, and complication rate is relatively higher. In the aspect of the effect on paraspinal muscles, in creatine kinase, multifidus cross-sectional area, and atrophy grading, minimally invasive surgery has no significant reduced damage on paraspinal muscles., Conclusion: Minimally invasive TLIF is not significantly superior to open TLIF, and it does not reduce the paraspinal muscles injury. But prospective double-blind randomized control trials are still needed for further study.