The relationship between paraspinal muscle atrophy and degenerative lumbar spondylolisthesis at the L4/5 level.

BACKGROUND/CONTEXT: Degenerative lumbar spondylolisthesis (DLS) is a prevalent spinal condition that can result in significant disability. DLS is thought to result from a combination of disc and facet joint degeneration, as well as various biological, biomechanical, and behavioral factors. One hypothesis is the progressive degeneration of segmental stabilizers, notably the paraspinal muscles, contributes to a vicious cycle of increasing slippage. PURPOSE: To examine the correlation between paraspinal muscle status on MRI and severity of slippage in patients with symptomatic DLS. STUDY DESIGN/SETTING: Retrospective cross-sectional study at an academic tertiary care center. PATIENT SAMPLE: Patients who underwent surgery for DLS at the L4/5 level between 2016-2018 were included. Those with multilevel DLS or insufficient imaging were excluded. OUTCOME MEASURES: The percentage of relative slippage (RS) at the L4/5 level evaluated on standing lateral radiographs. Muscle morphology measurements including functional cross-sectional area (fCSA), body height normalized functional cross-sectional area (HI) of Psoas, erector spinae (ES) and multifidus muscle (MF) and fatty infiltration (FI) of ES and MF were measured on axial MR. Disc degeneration and facet joint arthritis were classified according to Pfirrmann and Weishaupt, respectively. METHODS: Descriptive and comparative statistics, univariable and multivariable linear regression models were utilized to examine the associations between RS and muscle parameters, adjusting for confounders sex, age, BMI, segmental degeneration, and back pain severity and symptom duration. RESULTS: The study analyzed 138 out of 183 patients screened for eligibility. The median age of all patients was 69.5 years (IQR 62 to 73), average BMI was 29.1 (SD±5.1) and average preoperative ODI was 46.4 (SD±16.3). Patients with Meyerding-Grade 2 (M2, N=25) exhibited higher Pfirrmann scores, lower MFfCSA and MFHI, and lower BMI, but significantly more fatty infiltration in the MF and ES muscles compared to those with Meyerding Grade 1 (M1). Univariable linear regression showed that each cm2 decrease in MFfCSA was associated with a 0.9%-point increase in RS (95% CI -1.4 to - 0.4, p<.001), and each cm2/m2 decrease in MFHI was associated with an increase in slippage by 2.2%-points (95% CI -3.7 to -0.7, p=.004). Each 1%-point rise in ESFI and MFFI corresponded to 0.17%- (95% CI 0.05-0.3, p=.01) and 0.20%-point (95% CI 0.1-0.3 p<.001) increases in relative slippage, respectively. Notably, after adjusting for confounders, each cm2 increase in PsoasfCSA and cm2/m2 in PsoasHI was associated with an increase in relative slippage by 0.3% (95% CI 0.1-0.6, p=.004) and 1.1%-points (95% CI 0.4-1.7, p=.001). While MFfCSA tended to be negatively associated with slippage, this did not reach statistical significance (p=.105). However, each 1%-point increase in MFFI and ESFI corresponded to increases of 0.15% points (95% CI 0.05-0.24, p=.002) and 0.14% points (95% CI 0.01-0.27, p=.03) in relative slippage, respectively. CONCLUSION: This study found a significant association between paraspinal muscle status and severity of slippage in DLS. Whereas higher degeneration of the ES and MF correlate with a higher degree of slippage, the opposite was found for the psoas. These findings suggest that progressive muscular imbalance between posterior and anterior paraspinal muscles could contribute to the progression of slippage in DLS.

Modified Percutaneous Endoscopic Interlaminar Discectomy through the Near-spinous Process Approach for L4/5 Disc Herniation: A Retrospective Clinical Study.

OBJECTIVE: Compared with traditional open surgery, percutaneous endoscopic lumbar discectomy (PELD) has the advantages of less trauma, faster recovery, and less postoperative pain, so it has been widely used in the field of spinal surgery. However, it still has the defect of intraoperative fluoroscopy occurrences, complications, and even the risk of damage to the spinal cord and nerve. This study aims to compare the clinical efficacy of modified percutaneous endoscopic interlaminar discectomy (MPEID) with percutaneous endoscopic transforaminal discectomy (PETD) in treating L4/5 lumbar disc herniation (LDH) and to evaluate the effectiveness and safety of MPEID. METHODS: Thirty-four L4/5 LDH patients treated at the Second Affiliated Hospital of Nanchang University from June 2020 to June 2021 were studied retrospectively. Seventeen underwent MPEID and seventeen PETD. Variables analyzed included demographics, operative duration, intraoperative fluoroscopy occurrences, and surgical outcomes. Effectiveness was evaluated using the visual analogue scale (VAS), Oswestry disability index (ODI), and modified MacNab criteria. Lumbar Magnetic Resonance Imaging (MRI) was used to assess radiological outcomes. A paired t-test was performed to compare intragroup pre- and postoperative clinical data, VAS, and ODI scores. RESULTS: The average operative time in PETD group was 91.65 ± 14.04 min, and the average operative time in MPEID group was 65.41 ± 12.61 min (p < 0.001). In PETD group, the fluoroscopy occurrences averaged 9.71 ± 1.05 times, with fluoroscopy occurrences averaging 6.47 ± 1.00 times (p < 0.001) in MPEID group. At 12 months follow-up, the clinical effect showed significant improvement in both two groups. The MPEID group showed a decrease in average VAS-back score from 5.41 ± 2.18 to 1.76 ± 1.09 (p < 0.001) and VAS-leg score from 6.53 ± 1.66 to 0.82 ± 0.64 (p < 0.001). The ODI scores decreased from 51.35 ± 10.65 to 11.71 ± 2.91 (p < 0.001). In the PETD group, the VAS-back score decreased from 4.94 ± 1.98 to 2.06 ± 1.25 (p < 0.001), VAS-leg score from 7.12 ± 1.73 to 1.12 ± 0.60 (p < 0.001), and ODI scores from 48.00 ± 11.62 to 12.24 ± 2.56 (p < 0.001). According to the modified MacNab criteria, MPEID had 15 excellent and two good results; PETD had 12 excellent and 5 good (p = 0.23). No nerve root injuries, dural tears, or significant complications were reported. CONCLUSION: MPEID and PETD effectively treat L4/5 LDH, with MPEID showing shorter operative times and fewer fluoroscopies. Furthermore, the MPEID group can provide excellent clinical efficacy as the PETD group in the short term.

L4/5 accessibility for extreme lateral interbody fusion (XLIF): a radiological study.

INTRODUCTION: Potential advantages of the Extreme Lateral Interbody Fusion (XLIF) approach are smaller incisions, preserving anterior and posterior longitudinal ligaments, lower blood loss, shorter operative time, avoiding vascular and visceral complications, and shorter length of stay. We hypothesize that not every patient can be safely treated at the L4/5 level using the XLIF approach. The objective of this study was to radiographically (CT-scan) evaluate the accessibility of the L4/5 level using a lateral approach, considering defined safe working zones and taking into account the anatomy of the superior iliac crest. METHODS: Hundred CT examinations of 34 female and 66 male patients were retrospectively evaluated. Disc height, lower vertebral endplate (sagittal and transversal), and psoas muscle diameter were quantified. Accessibility to intervertebral space L4/5 was investigated by simulating instrumentation in the transverse and sagittal planes using defined safe zones. RESULTS: The endplate L5 in the frontal plane considering defined safe zones in the sagittal and transverse plane (Zone IV) could be reached in 85 patients from the right and in 83 from the left side. Through psoas split, the safe zone could be reached through psoas zone II in 82 patients from the right and 91 patients from the left side. Access through psoas zone III could be performed in 28 patients from the right and 32 patients from the left side. Safe access and sufficient instrumentation of L4/5 through an extreme lateral approach could be performed in 76 patients of patients from the right and 70 patients from the left side. CONCLUSION: XLIF is not possible and safe in every patient at the L4/5 level. The angle of access for instrumentation, access of the intervertebral disc space, and accessibility of the safe zone should be taken into account. Preoperative imaging planning is important to identify patients who are not suitable for this procedure.

Comparison of the Outcomes of Microendoscopic Discectomy Versus Full-Endoscopic Discectomy for the Treatment of L4/5 Lumbar Disc Herniation.

STUDY DESIGN: Retrospective Comparative Study. OBJECTIVES: To compare the outcomes of microendoscopic discectomy (MED) versus full-endoscopic discectomy (FED) for treating L4/5 lumbar disc herniation (LDH). METHODS: A retrospective study was performed on patients with L4/5 LDH treated using MED (n = 249) or FED (n = 124). A 16-mm tubular retractor and endoscope was used for MED, while a 4.1-mm working channel endoscope was used for FED. Patient background and operative data were collected. The Oswestry Disability Index (ODI) and European Quality of Life-5 Dimensions (EQ-5D) scores were recorded preoperatively and at 1 and 2 years postsurgery. RESULTS: The background data of the two groups were similar. The mean operation times for MED and FED were 59.3 and 47.7 min (respectively), and the mean volumes of removed nucleus pulposus were .65 and 1.03 g, respectively. These differences were significant (P < .001). Six dural tears and one postoperative hematoma were observed in the MED group; none were observed in the FED group. During the follow-up period, 16 MED and 7 FED patients required re-operation due to recurrence (P = 1.00). Although the ODI and EQ-5D scores significantly improved at 1 and 2 years postsurgery in both groups, the differences were not statistically significant. CONCLUSIONS: Operative outcomes were almost identical in both groups. We did not observe any operative or postoperative complications in FED. We, therefore, recommend FED as the first option for the treatment of L4/5 LDH since it has a better safety profile and is minimally invasive.

Clinical comparison of unilateral biportal endoscopic discectomy with percutaneous endoscopic lumbar discectomy for single l4/5-level lumbar disk herniation.

OBJECTIVE: The purpose of this research was to investigate the outcomes between unilateral biportal endoscopic discectomy (UBE) and percutaneous endoscopic lumbar discectomy (PELD) for the single L4/5-level lumbar disk herniation (sLDH). METHODS: From January 2018 to January 2021, a total of 40 patients with sLDH were retrospectively analyzed in this study. All the patients had received spinal surgeries in Affiliated Hospital of Nantong University and Affiliated Nantong Hospital 3 of Nantong University. Among them, 20 patients were treated with PELD (PELD group), and 20 patients were treated with UBE discectomy (UBE group). Postoperative length of hospital stay, estimated blood loss, operation time, and clinical complications of the patients were compared between the two groups. The visual analog scale (VAS) and Oswestry Disability Index (ODI) were measured before surgeries and 3 days, 1, and 6 months after surgeries. RESULTS: Compared with the UBE group, the PELD group had obviously less intraoperative blood loss, shorter operative time, and shorter hospital stay. The differences in the rate of complications were not statistically significant between the two groups. The VAS score and the ODI score of the two groups had a great reduction after operation. In addition, both the groups had satisfactory clinical outcome; the VAS score and ODI of the PELD group decreased more obviously. CONCLUSION: The UBE for sLDH yielded similar clinical outcomes to PELD as minimally invasive surgeries; however, PELD is superior to UBE in terms of intraoperative blood loss, operative time, postoperative hospitalization, and short-term postoperative pain relief. The advantages and disadvantages of the two surgeries should be circumspectly balanced when evaluating a patient for a minimally invasive surgery for sLDH, selecting the most appropriate surgical method for patients.

Early Clinical Outcomes of Percutaneous Endoscopic Lumbar Discectomy for L4-5 Highly Down-Migrated Disc Herniation: Interlaminar Approach Versus Transforaminal Approach.

OBJECTIVE: This study is a retrospective evaluation of patients with L4-5 highly down-migrated lumbar disc herniation (LDH) operated with interlaminar endoscopic lumbar discectomy (IELD) versus transforaminal endoscopic lumbar discectomy (TELD). METHODS: From January 2015 to December 2018, 77 patients with L4-5 highly down-migrated LDH were divided into 2 groups according to different surgical approaches. There were 40 patients who underwent IELD, and 37 patients who underwent TELD. The operation time, hospital stay, Oswestry Disability Index, clinical outcome according with modified MacNab criteria, Visual Analog Scale (VAS) scores, and complications were compared between the IELD and TELD groups. RESULTS: Seventy-seven patients were included, 40 and 37 patients underwent IELD and TELD, respectively. The IELD and TELD groups both achieved a significant improvement in Oswestry Disability Index, back and leg VAS scores, and clinical outcome postoperation. Mean operating and x-ray times during operation were significantly shorter in the IELD group than in the TELD group (41.8 vs. 50.3, 1.8 vs. 13.7). There were 3 patients who experienced recurrence in the IELD group and 2 in the TELD group. In the TELD group, there were 3 patients who required revision surgery due to incompletely removed disc fragment. All patients in the IELD group were treated successfully. There was no other complication in these cases. CONCLUSIONS: Both IELD and TELD could be a good alternative option for highly down-migrated LDH in L4-L5. IELD may have advantages in operation time and x-ray times during operation compared with TELD.

Decade-Wise Computed Tomography-Based Morphometric Measurements of a Single Lumbar Spinal Motion Segment L4-5.

BACKGROUND: A spinal motion segment comprises facet joints and intervertebral disc. A complex interplay of biomechanical factors occurs between them with degeneration giving rise to numerous pathological conditions. We conducted a study to find a correlation between facet joint orientation and intervertebral discs with age. METHODS: A cross-sectional study of 203 consecutive subjects undergoing a computed tomography scan of abdomen and pelvis were included. Subjects were divided into 5 groups based on age (group I: 18-30 years; group II: 31-40 years; group III: 41-50 years; group IV: 51-60 years; group V: 61-70 years). Using 3-dimensional reconstruction images, orientation of lumbar facet joints at the L4-5 level was measured. Similarly, adjacent disc heights at L3-4 and L4-5 were measured and their ratio was documented. RESULTS: The study included 106 males and 97 females. A positive correlation was noted between age and sagittal facet orientation until age 60 years. However, after age 60 years, a negative correlation with age was seen, which was statistically significant. Similarly, the disc height ratios show a progressive decline in their values with age. However, this decline was statistically significant only after age 60 years. CONCLUSION: The gradual change of facet joint orientation from sagittal to coronal as the age crosses from 30 to 60, to beyond 60, with a simultaneous and parallel diminishing in the disc height probably is one of the attributes of the phenomenon of autostabilization of a motion segment.

Transplantation of microencapsulated olfactory ensheathing cells inhibits the P2X2 receptor over-expressionmediated neuropathic pain in the L4-5 spinal cord segment.

OBJECTIVES: The purpose of this study was to determine the effect of microencapsulated olfactory ensheathing cells (MC-OECs) transplantation on neuropathic pain (NPP) caused by sciatic nerve injury in rats, and its relationship with the expression levels of P2X2 receptor (P2X2R) in the L4-5 spinal cord segment. METHODS: Olfactory bulb tissue was removed from a healthy Sprague-Dawley (SD) rat for culturing olfactory ensheathing cells (OECs). Forty-eight SD rats were randomly divided into four groups (12 per group): the sham, chronic constriction injury (CCI), olfactory ensheathing cells (OECs), and MC-OECs groups. On days 7 and 14 after surgery, the mechanical withdrawal thresholds (MWT) were measured by using behavioral method. The expression levels of P2X2R in the L4-5 spinal cord segment were detected by in situ hybridization and Western blotting. RESULTS: On days 7 and 14 post-surgical, the MWT of rats from high to low were the sham, MC-OECs, OECs, and CCI groups, the MWT of rats in the MC-OECs groups were higher than that in OECs groups. The expression levels of P2X2R in the L4-5 spinal cord segment from high to low were the CCI, OECs, MC-OECs, and sham groups, the expression levels of P2X2R were lower than that in OECs groups. All differences between groups were statistically significant (p value <.05). CONCLUSIONS: OECs and MC-OECs transplantation can reduce the expression levels of P2X2R genes in the L4-5 spinal cord segment, and relieve NPP. The therapeutic efficacy of MC-OECs transplantation was better than the transplantation of OECs.

Traumatic bilateral L4-5 facet fracture dislocation: a case presentation with mechanism of injury.

BACKGROUND: Traumatic bilateral locked facet joints at L4-5 level are a rare entity. A careful review only revealed four case reports. This case presented with an unusual mechanism of injury. CASE PRESENTATION: We present a case of a 40-year-old male who suffered bilateral L4-5 traumatic facet fracture dislocation following a fall injury. The dislocation was associated with fractures of bilateral L4 inferior articular processes, left L4 pedicle, L4 spinous process and postero-inferior body of L4. He presented with cauda-equina syndrome and underwent emergency decompression, reduction and instrumented fusion. CONCLUSION: The biomechanics of the lumbar spine may differ with each individual. L4-5 dislocation may be a variant to lumbosacral (L5-S1) dislocation, owing to hyperextension injury.

Microencapsulated olfactory ensheathing cell transplantation reduces P2X4 receptor overexpression and inhibits neuropathic pain in rats.

OBJECTIVES: The aim of this study was to determine the role of microencapsulated olfactory ensheathing cells (MC-OECs) transplantation in rats with sciatic nerve injury-induced neuropathic pain, and its relationship with P2X4 receptor expression in the L4-5 spinal cord segment. METHODS: Olfactory bulb tissues of healthy Sprague Dawley (SD) rats were collected to culture olfactory ensheathing cells (OECs) using differential attachment methods. Seventy-two healthy SD rats were randomly assigned to four groups: the sham, chronic constriction injury (CCI), OECs, and MC-OECs groups. Mechanical paw withdrawal thresholds were measured on days 7, 14 and 21 after surgery. The expression of P2X4 receptor genes in the L4-5 spinal cord segment was detected by in situ hybridization, western blotting and RT-PCR. RESULTS: On post-surgical days 7, 14 and 21. The mechanical paw withdrawal thresholds of rats from low to high were the CCI, OECs, MC-OECs and sham groups. The expression level of P2X4 receptor mRNA and protein from low to high were the sham, MC-OECs, OECs and CCI groups. Compared with the OECs group, the mechanical paw withdrawal thresholds of rats were increased, and the expression level of P2X4 receptor mRNA and protein were decreased in the MC-OECs group. In addition, the mechanical paw withdrawal thresholds of rats were higher and the expression level of P2X4 receptor were lower in the MC-OECs group on post-surgical days 21 than that on days 7 and 14. All differences between groups were statistically significant (P value < 0.05). CONCLUSIONS: OECs and MC-OECs transplantation can reduce the expression level of P2X4 receptor and relieve pain. The therapeutic efficacy was better in the MC-OECs group than in the OECs group. MC-OECs transplantation have the better effects of treatment with the increase of MC-OECs transplantation time.

Effects of microencapsulated olfactory ensheathing cell transplantation on neuropathic pain and P2X7 receptor expression in the L4-5 spinal cord segment.

OBJECTIVES: The aim of this study was to determine the role of microencapsulated olfactory ensheathing cell (MC-OEC) transplantation in rats with sciatic nerve injury-induced pain, and its relationship with P2 × 7 receptor expression in the L4-5 spinal cord segment. METHODS: Olfactory bulb tissues of healthy Sprague Dawley (SD) rats were collected to culture olfactory ensheathing cells using differential attachment methods. Forty-eight healthy SD rats were randomly assigned to four groups: the sham, chronic constriction injury (CCI), olfactory ensheathing cell (OEC), and MC-OEC groups. Mechanical paw withdrawal thresholds were measured on days 7 and 14 after surgery. The expression of P2 × 7 receptor genes in the L4-5 spinal segment was detected by in situ hybridization and western blotting. RESULTS: On post-surgical days 7 and 14, the mechanical paw withdrawal thresholds of rats in the MC-OEC, OEC and CCI were lower than that in the sham group. The mechanical paw withdrawal thresholds of rats in the MC-OEC and OEC were higher than that in the CCI group, compared with the OEC group. The mechanical paw withdrawal thresholds of rats in the MC-OEC were increased. The expression levels of P2 × 7 receptors in the L4-5 spinal cord segment in the CCI, OEC and MC-OEC were higher than that in the sham group, the expression levels of P2 × 7 receptors in the MC-OEC and OEC group were lower than that in the CCI group, compared with the OEC group, the expression levels of P2 × 7 receptors in the MC-OEC were decreased. All differences between groups were statistically significant (P value <0.05). CONCLUSIONS: OEC and MC-OEC transplantation can relieve pain and reduce the expression level of P2 × 7 receptors in the L4-5 spinal cord segment. The therapeutic efficacy was better in the MC-OEC group than in the OEC group.

Effects of microencapsulated olfactory sheathing cells transplantation on neuropathic pain and the expression of P2X7 receptor in L4.5 spinal cord / 解剖学报

Objective To investigate the cflecl of microencapsulated olfactory sheathing cells transplantation on pathological pain induced by peripheral nerve injury and the expression levels of P2X7 receptor in L4., spinal cord. Methods Nash differential adherence method was used to cultivate and expand cells from olfactory bulb tissue of a SD rat. Forty healthy SD rats were randomly divided into control group, model group, OFCs group and microencapsulated OECs group (MC-OECs groups). At the 7th and 14th days after surgery, the mechanical stimulation constraining thresholds of the rats in each group were measured by behavioral method. The experssion levels of P2X7 receptor positive cells percentage and average absorbance by in situ hybridization were observed in L4-J spinal cord. Results At the 7th and 14th days after surgery, compared with the control group, the reflex threshold of mechanical withdrawl of rats in the CCI group significantly decreased(P<0. 05). The percentage and average absorbance of P2X7 receptor positive cells in L4., spinal cord significantly increased(PcO. 05) compared with the CCI group, the reflex threshold of mcchaniral withdrawl of rats in the OF.Cs group was significantly increased (/'cO. 05). The percentage and average absorbance of P2X7 receptor positive cells in L«., spinal cord significantly decreased compared with the OECs group(P<0. 05). The reflex threshold of mechanical withdrawl of rats in the MC-OECs group was higher(/,<0. 05). The percentage and average absorbance of P2X7 receptor positive cells in L4., spinal cord were lower(H<0. 05). Conclusion Microencapsulated olfactory ensheathing cells transplantation can relieve the neuropathic pain belter and reduce the expression levels of P2X7 receptor and repair peripheral nerve injury than OECs transplantate.

Resolution of the more anteriorly positioned psoas muscle following correction of spinal sagittal alignment from spondylolisthesis: case report.

Several studies have described the radiographic, histological, and morphological changes to the paraspinal muscle in patients with chronic low-back pain due to degenerative diseases of the spine. Gross anatomical illustrations have shown that the psoas muscle lies lateral to the L4-5 vertebrae and subsequently thins and dissociates from the vertebral body at L5-S1 in a ventrolateral course. A "rising psoas" may influence the location of the lumbar plexus and result in transient neurological injury on lateral approach to the spine. It is postulated that axial back pain may be exacerbated by anatomical changes of paraspinal musculature as a direct result of degenerative spine conditions. To their knowledge, the authors present the first reported case of a more anteriorly positioned psoas muscle and its resolution following correction of spondylolisthesis in a 62-year-old woman. This case highlights the dynamic nature of degenerative spinal disorders and illustrates that psoas muscle position can be affected by sagittal balance. Normal anatomical positioning can be restored following correction of spinal alignment.

Pelvic nodal CTV from L4-L5 or aortic bifurcation? An audit of the patterns of regional failures in cervical cancer patients treated with pelvic radiotherapy.

OBJECTIVE: To assess the patterns of recurrence in cervical cancer patients treated with pelvic nodal clinical target volume at L4-L5 junction instead of aortic bifurcation. METHODS: Records of patients with locally advanced cervical cancer treated with chemo-radiation were reviewed. Patients treated with standard pelvic fields (superior border of the field at L4/L5 junction), without any radiological evidence of regional lymphadenopathy (<10 mm) were included in the study. The level of aortic bifurcation was retrospectively documented on computed tomography. Patterns of recurrences were correlated to the aortic bifurcation and the superior border of the radiation fields (L4/L5). RESULTS: Aortic bifurcation was above the radiation fields (above L4/5) in 82 of 116 (70.7%) patients. Of the nine patients that recurred above the radiation field, 5 (55%) were above L4/5 failures, i.e. between aortic bifurcation and L4/5, and 4 (45%) had para-aortic failures. On retrospective analysis, 16 patients were found to have subcentimeter lymph nodes and higher nodal failures (7/16) were observed in patients with subcentimeter regional lymph nodes at diagnosis. CONCLUSIONS: Superior border of nodal clinical target volume should ideally include the aortic bifurcation instead of L4-L5 inter space in patients with locally advanced cervical cancer. Radiotherapy fields need to be defined cautiously in patients with subcentimeter pelvic lymph nodes.

Trunk muscle contributions of to L4-5 joint rotational stiffness following sudden trunk lateral bend perturbations.

The purpose of this research was to investigate the contributions of individual muscles to joint rotational stiffness and total joint rotational stiffness about the lumbar spine's L(4-5) joint prior to, and following, sudden dynamic lateral perturbations to the trunk. Kinematic and surface EMG data were collected while subjects maintained a kneeling posture on a robotic platform, while restrained so that motions caused by the perturbation were transferred to the pelvis, causing motion of the trunk and head. The robotic platform caused sudden inertial trunk lateral perturbations to the right or left, with or without timing and direction knowledge. An EMG-driven model of the lumbar spine was used to calculate the muscle forces and contributions to joint rotational stiffness during the perturbations. Data showed 95% and 106% increases in total joint rotational stiffness, about the lateral bend and axial twist axes, when subjects had knowledge of the timing of the perturbation. Also, the contralateral muscles exhibited a significantly larger total joint rotational stiffness about the lateral bend axis, and earlier surface EMG responses, than the ipsilateral muscles. The results indicate that, when the timing of the perturbation was unknown, subjects relied more on delayed muscle forces following the perturbation to stiffen the L(4-5) joint.

A Prospective Comparison of Surgical Approach for Lateral Retroperitoneal L4-5 Fusion: Laparoscopic Versus Mini-ALIF / 대한척추외과학회지

STUDY DESIGN: We have analyzed the laparoscopic lateral retroperitoneal approach of the L4-5 interspace to the miniopen retroperitoneal approach for lateral lumbar interbody fusion. OBJECTIVES: To prospectively compare the laparoscopic lateral retroperitoneal approach of the L4-5 interspace to the miniopen retroperitoneal approach for lateral lumbar interbody fusion Summary of Background Data : The introduction of laparoscopic techniques in 1993 has stimulated a great deal of discussion regarding the risks and benefits of such minimally invasive approaches. In many centers the anterior endoscopic approach to L5-S1 has become routine. However exposure at L4-5 can be much more difficult. MATERIALS AND METHODS: From 1997 to 1999 thirty eight patients were entered into a prospective study. These patients were all undergoing anterior interbody fusion at the L4-5 level. The patients were divided into two groups for analysis. Group I patients underwent anterior interbody fusion utilizing threaded interbody devices placed via laparoscopic lateral retroperitoneal approach. Group II patients underwent anterior lumbar interbody fusion using threaded interbody devices placed via a miniopen retroperitoneal approach. RESULTS: In Group I, Operation time was 48 minutes longer than Group II (p=0.035) but there were no significant statistical differences in bleeding amount and hospitalization period. Parethesia and tingling sensation of thigh were developed in two cases of Group I patients, one case of Group II patients but they were gradually diminished. In Group I, only one cage was inserted in five cases of patients (28%) who had an inadequate exposure of L4-5 area. However, all of the patients in Group II (100%) had an adequate exposure of L4-5 area. CONCLUSION: The surgical results of laparoscopic technique was not superior to miniopen technique.