Biomechanical Characteristics of Lumbar Fusion by Three Internal Fixation Methods / 医用生物力学

Objective To analyze the biomechanical characteristics of lumbar fusion by 3 internal fixation methods using three-dimensional (3D) finite element (FE) method. Methods The FE fixation models of physiological L4-5, unfixed fusion L4-5, translaminar facet screw (TLFS), lumbar pedical screw+translaminar facet screw (LPS+TLFS), bilateral pedical screw (BPS) with complete osteotomy or partial osteotomy of facet joint were established, respectively. The biomechanical characteristics of L4 centrum and implants under six motion states (spinal flexion, extension, lateral bending and axial rotation) in L4-5 fusion model and three fixation models were compared by FE analysis. Results The average maximal displacements of L4 centrum in L4-5 unfixed fusion model, TLFS model, TLFS+LPS model, BPS model were 1.410 8, 0.629 8, 0.336 9, 0.252 8 mm (complete osteotomy of facet joint) and 1.296 7, 0.844 9, 0.340 9, 0.273 8 mm (partial osteotomy of facet joint); the average maximal displacements of cage were 0.479 9, 0.319 5, 0.167 6, 0.126 4 mm (complete osteotomy of facet joint) and 0.378 7, 0.348 4, 0.183 5, 0.137 2 mm (partial osteotomy of facet joint)；the average maximum stresses of screws and rods during 6 motions in TLFS model, TLFS+LPS model, BPS model were 178.34, 79.55, 56.33 MPa (complete osteotomy of facet joint) and 142.29, 103.02, 59.69 MPa (partial osteotomy of facet joint). Conclusions In percutaneous transforaminal lumbar interbody fusion, the fixation effect of BPS model was similar to that of LPS+TLFS model. BPS model could achieve the best spinal stability, and LPS+TLFS model was also a good fixation method. The stability of TLFS model alone was relatively poor, but it was still better than that of cage bone graft without internal fixation. In the absence of internal fixation, preservation of the articular process significantly increased stability of the spine.

Biomechanical characteristics of transforaminal lumbar interbody fusion combined with different pedicle screw fixation methods in single-segment lumbar spine and adjacent segments / 中国组织工程研究

BACKGROUND: Decompression-fixation-fusion is the key to spinal surgery since early effective fixation to achieve intervertebral fusion can restore spinal stability in lumbar degenerative disease. OBJECTIVE: To compare biomechanical stability of fusion segment and adjacent segments of bilateral pedicle screw fixation, unilateral pedicle screw fixation and unilateral pedicle screw combined with contralateral translaminar facet screw fixation under transforaminal lumbar interbody fusion. METHODS: Eighteen fresh calf L3-5 specimens were selected. Different forms of fixation were conducted under transforaminal lumbar interbody fusion. The specimens were divided into group A (complete specimens) and group B (bilateral pedicle screws), group C (unilateral pedicle screws), and group D (unilateral pedicle screw combined with contralateral translaminar facet screw). The range of motion of adjacent segment L3-4 and fusion segment L4-5 in six directions of backward extension, forward bending, left bending, right bending, left rotation and right rotation and the stiffness of fusion segment L4-5 were tested. RESULTS AND CONCLUSION: (1) For the range of motion of fusion segment L4-5, the stability was highest in the group B in six directions, followed by group D, which showed similar results in rotation in the group B (P > 0.05). The stability of right curvature and left rotation in group C was insufficient, and there was no significant difference in range of motion between group A and group C (P > 0.05). The range of motion in group A was largest and the stability was worst in the six motion directions. (2) For the stiffness value of fusion segment L4-5, the stiffness value of group B was largest in six directions, which was significantly different from other groups (P 0.05). There was no significant difference between group C and group A in the range of motion of six directions (P > 0.05). (4) The results showed that the motion ramge of unilateral pedicle screw fixation in the right and left rotation directions was large in the early stage, which was close to that of the complete specimen group. There is a shortage of stability, so we need to use it carefully and grasp the indications strictly. Unilateral pedicle screw fixation combined with contralateral translaminar facet screw fixation improves the disadvantages of asymmetric fixation of unilateral pedicle screw, increases the stability of rotation and lateral bending, and avoids the influence of bilateral pedicle screw fixation on adjacent segments, thus becoming an effective clinical surgical treatment.

Case control study on two different surgical approaches combined fixation with lumbar interbody fusion for the treatment of single segmental lumbar vertebra diseases / 中国骨伤

<p><b>OBJECTIVE</b>To discuss the advantages and disadvantages of two different surgical approaches combined fixation with lumbar interbody fusion in treating single segmental lumbar vertebra diseases.</p><p><b>METHODS</b>The clinical data of 86 patients with single segmental lumbar vertebra diseases treated from June 2011 to June 2013 was retrospectively analyzed. There were 33 males and 53 females, aged from 28 to 76 years old with an average of 53.0 years. Among them, there were 39 cases of lumbar disc degeneration, 22 cases of lumbar disc herniation complicated with spinal canal stenosis, 9 cases of huge lumbar disc herniation and 16 cases of lumbar degenerative spondylolisthesis (Meyerding degree I ). Lesion sites contained L3, 4 in 5 cases, L4, 5 in 70 cases and L5S1 in 11 cases. All the patients were treated with internal fixation and lumbar interbody fusion with 45 cases by midline incision approach (median incision group) and the other 41 cases by channel-assisted by muscle-splitting approach(channel group). Incision length, operation time, intraoperative bleeding and postoperative drainage were recorded in two groups. Visual analogue scale(VAS) was used to assess lumbar incision pain 72 h after operation. Depended on imaging results to compare the changes of the disc space height in lesion in preoperative, postoperative and final follow-up, the coronal and sagittal Cobb angle in preoperative and final follow-up, the area of multifidus and the degree of multifidus fat deposition before and after operation between two groups. Loosening or fragmentation of internal fixation, displacement of intervertebral cage and interbody fusion were observed in each group. Japanese Orthopedic Association (JOA) scoring system was used to evaluate the function before operation and at the final follow-up.</p><p><b>RESULTS</b>The channel group was superior to the median incision group in incision length and postoperative drainage while the median incision group was less than the channel group in the operation time and intraoperative bleeding. The average VAS score of lumbar incision 72 h after operation was 1.50 points in median incision group and 0.97 points in channel group, and there was significant difference between two groups(<0.05). No incision infection was found, but there were 4 cases of incisional epidermal necrosis, 1 case of incision healed badness, and 3 cases of nerve injury in channel group. The incidence of cacothesis of pedicle screw were 5.0% and 3.6% in median incision group and channel group respectively, and there was no significant difference between two groups(>0.05). The incidence of cacothesis of translaminar facet screw were 6.6% and 12.2% in median incision group and channel group respectively, and there was significant difference between two groups(<0.05). All the patients were followed up for 12 to 36 months with a mean of 22.8 months. The changes of disc space height had statistical difference between preoperative and postoperative(<0.05) in all patients, but there was no significant difference between postoperative and final follow-up(>0.05), however, there was no significant difference 3 days after operation and final follow-up between two groups(>0.05). At final follow-up, coronal and sagittal Cobb angle were obviously improved in all patients(<0.05), but there was no significant difference between two groups(>0.05). One year after operation, the area of multifidus in median incision group was (789.00±143.15) mm² less than preoperative(1 066.00±173.55) mm² (<0.05), and in channel group, was(992.00±156.75) mm² at 1 year after operation and(1 063.00±172.13) mm² preoperatively, there was no significant difference between them(>0.05), however, there was significant difference one year after operation between two groups (<0.05) . About the degree of multifidus fat deposition, there was significant difference between one year after operation and preoperation in median incision group (<0.05), but there was no significant difference between one year after operation and preoperation in channel group (>0.05), and there was significant difference at one year after operation between two groups(<0.05). During the follow-up period, neither pedicle screw and/or translaminar facet screw loosening, displacement or fragmentation nor displacement of intervertebral cage were found. The lumbar interbody fusion rate was 95.6% in median incision group and was 95.1% in channel group, and there was no significant difference between two groups(>0.05). No obvious adjacent segmental degeneration was observed in fixed position. JOA score in median incision group was significantly increased from 8-16 points (average: 12.77±2.56) preoperative to 21-29 points (average: 25.20±2.43) at final follow-up(<0.05); and in channel group was significantly increased from 8-16 points (average: 12.64±2.37) preoperative to 23-29 points(average: 26.7±1.82) at final follow-up(<0.05); there was also significant difference between two groups at final follow-up.</p><p><b>CONCLUSIONS</b>Compared to the median incision approach, unilateral pedicle screw combined with contralateral translaminar facet screw fixation using channel-assisted by muscle-splitting approach has advantages of small incision, less trauma, fast recovery and so on. However, it also has shortages such as high surgical complications incidence, especially in cases that.</p>

Feasibility of Translaminar Screw Placement in Korean Population: Morphometric Analysis of Cervical Spine

PURPOSE: To analyze the feasibility of unilateral and bilateral translaminar screw placement in Koran population, and compare the acceptance rate using previously reported data in American population. MATERIALS AND METHODS: The translaminar lengths, thickness, heights, and sagittal-diagonal measurements were performed. The feasibility analysis was performed using unilateral and bilateral 3.5 mm cervical screw placement on the CT scans within 0.5 mm of safety margin. We also performed radiographic analysis of the morphometric dimensions and the feasibility of unilateral and bilateral translaminar screw placement at C3-C7. RESULTS: Korean population had similar or significantly shorter translaminar lengths and thickness (lengths and thickness in C7 among males; lengths in C6-C7 and thickness in C4 among females) than American population, but had similar or significantly longer translaminar heights and sagittal-diagonal measurements (heights in C3-C7 and sagittal-diagonal measurements in C3-C6 among males; heights in C7 and sagittal-diagonal measurements in C3-C7 among females). Unilaterally, translaminar screw acceptance rates in C3-C7 were similar between Korean and American male population, but the rates in C4-C6 were significantly smaller between Korean and American female population. Bilaterally, translaminar screw acceptance rates in C3 and C5-C6 were significantly larger between Korean and American male population, but the rates in C3-C7 were similar between Korean and American female population. CONCLUSION: The feasibility of unilateral and bilateral translaminar screw placement is different depending on different ethnics. Subaxial cervical unilateral translaminar screw placement among Korean male population and bilateral placement at C4-C7 among Korean female population are more acceptable than American population.

Bilateral Pedicle and Crossed Translaminar Screws in C2

Multiple techniques exist for the fixation of C2, including axial pedicle screws and bilateral translaminar screws. We describe a novel method of incorporating both the translaminar and pedicle screws within C2 to improve fixation to the subaxial spine in patients requiring posterior cervical instrumentation for deformity correction or instability. We report three cases of patients with cervical spinal instability, who underwent cervical spine instrumentation for stabilization and/or deformity correction. Bilateral C2 pedicle screws were inserted, followed by bilateral crossed laminar screws. The instrumentation method successfully achieved fixation in all three patients. There were no immediate postoperative complications, and hardware positioning was satisfactory. Instrumenting C2 with translaminar and pedicle screws is technically feasible, and it may improve fixation to the subaxial spine in patients with poor bone quality or severe subaxial deformity, which require a stronger instrumentation construct.

Translaminar Microendoscopic Herniotomy for Cranially Migrated Lumbar Disc Herniations Encroaching on the Exiting Nerve Root in the Preforaminal and Foraminal Zones

STUDY DESIGN: Case series. PURPOSE: The aim of this study was to describe translaminar microendoscopic herniotomy (TL-MEH) for cranially migrated lumbar disc herniations encroaching on the exiting nerve root in the preforaminal and foraminal zones and to report preliminary results of the procedure. OVERVIEW OF LITERATURE: Conventional interlaminar approaches for preforaminal and foraminal lumbar disc herniations result in extensive removal of the lamina and facet joint to remove disc fragments safely. More destructive approaches increase the risk of postoperative segmental instability. METHODS: TL-MEH is a minimally invasive procedure for herniotomy via the translaminar approach using a microendoscopic technique. TL-MEH was performed in seven patients with a cranially migrated lumbar disc herniation encroaching on the exiting nerve root. The disc fragments were located in the preforaminal zone in four patients, and in the preforaminal and foraminal zones in three. RESULTS: All patients experienced immediate relief from symptoms after surgery and satisfactory results at the final follow-up. Surgical complications, such as a dural tear, nerve injury, and surgical site infection, were not investigated. CONCLUSIONS: TL-MEH seemed to be an effective and safe alternative minimally invasive surgical option for patients with a cranially migrated lumbar disc herniation encroaching the exiting nerve root in the preforaminal and foraminal zones.

Efficacy of Translaminar Epidural Steroid Injection versus Combined Translaminar Epidural Steroid Injection with Selective Nerve Root Injection in Spinal Stenosis

OBJECTIVE: To compare treatment effects of translaminar epidural steroid injections (TLESIs) only and selective nerve root injections (SNRIs) with TLESIs in lumbosacral spinal stenosis. METHOD: Thirty-four patients diagnosed with magnetic resonance imaging (MRI), somatosensory evoked potential (SEP) and electromyography (EMG) were included. 16 patients who had somatosensory pathway dysfunction or abnormal spontaneous activity received combined SNRIs with TLESIs and 20 patients received only TLESIs. The visual analogue scale (VAS) and functional rating index (FRI) were measured before injection, 1 week and 3 months after 3 times injection. RESULTS: The mean values of VAS before injection, 1 week and 3 months after 3 times injection were 7.55, 3.22, 3.61 in only TLESIs and 7.37, 2.06, 2.31 in SNRIs with TLESIs. The mean values of FRI before injection, 1 week and 3 months after 3 times injection were 25.16, 16.00, 15.83 in only TLESIs and 22.50, 8.37, 8.31 in SNRIs with TLESIs. In the mean values of VAS and FRI were significantly lower SNRIs with TLESIs than only TLESIs (p<0.05). CONCLUSION: Combined SNRIs with TLESIs were more effective treatment for reduction of pain and improvement of function than only TLESIs in lumbosacral spinal stenosis.

Posterior Lumbar Intebody Fusion with Unilateral Transpedicular Screw and Contralateral Translaminar Facet Screw Fixation in Lumbar Spinal Stenosis / 대한척추외과학회지

STUDY DESIGN: A retrospective study. OBJECTIVES: To describe the surgical procedure and assess the results of an unilateral transpedicular screw and contralateral translaminar facet screw fixation in degenerative lumbar stenosis. SUMMARY OF LITERATURE REVIEW: A drawback of conventional lumbar fusion is the extensive soft-tissue destruction that is essential when inserting a screw and preparing the fusion bed. The development of a procedure that minimizes the tissue trauma without compromising the effectiveness of the conventional posterior lumbar interbody fusion (PLIF) should be pursued in lumbar spinal stenosis. MATERIALS AND METHODS: From August 2004 to November 2005, PLIF was performed on 25 consecutive patients who had lumbar spinal stenosis. Among them, 10 patients underwent with unilateral transpedicular screw and contralateral translaminar facet screw fixation (Group 1), and 15 patients underwent traditional bilateral transpedicular screw fixation (Group 2). The clinical and radiological results in the two groups were compared. RESULTS: The mean follow-up was 17.6 and 20.5 months in Groups 1 and 2, respectively. Group 1 had less blood loss, fewer transfusion requirements (P.0.05) in the surgical procedure, and less postoperative back pain (P.0.05). There was no significant difference between the two groups in the clinical results such as the VAS score for back pain and the Kirkadly-Willis criteria at the last follow-up, and the radiological results such as the changes in the disc height and interbody fusion. CONCLUSION: The PLIF with unilateral transpedicular screw and contralateral translaminar facet screw fixation in lumbar spinal stenosis has advantages over conventional PLIF of less soft tissue injury, and produces good clinical results.

Experimental research on biomechanical stability about L_5S_1 ALIF / 中国矫形外科杂志

[Objective] To evaluate the biomechanical stability of lumbar intact specimen,anterior lumbar interbody fixation(ALIF)specimen,ALIF specimen fixed with pedicle screw and ALIF specimen fixed with translaminar facets screw.[Method]Each of eight adult fresh cadaver specimen of lumbarsacral segmcnts was analyzed in four states(groups):intact,L5S1 ALIF,L5S1 ALIF fixed with pedicle screw or fixed with translaminar facets screw,test and compare its range of motion(ROM)in flexion,extension,lateral bending and axial rotation.[Result]The ROM of ALIF specimen in extension was larger than that of intact specimen(P

Placement of percutaneous translaminar facet screw: an anatomic study / 中国矫形外科杂志

[Objective]To provide anatomic basement for the clinic appliance of percutaneous thranslaminar facet screw.[Method]From L_1 to L_5,anatomic measurements for screw path length,superior and inferior lamina border thickness in 30 dried lumbar spines,caudal and lateral angles of laminar were measured with CT and X ray.[Result]The superior border of the lamina was relatively thinner from L_1 to L_5,The thickness of the inferior border of the lamina,the mean values of the length of the screw path and lateral angle gradually increased,and the caudal angle of screw placement relative to transverse plane gradually decreased.[Conclusion]A translaminar facet screw with 4.5 mm in diameter is safe.from L_(1~5).Screw should be inserted in inferior lamina border,not in the superior border of the lamina,caudal and lateral angles of laminar should be ajustable to fit the lumbar facet joint.

Posterior C1-2 Stabilization Using Translaminar Screw Fixation of the Axis

We report a case of C1-2 instability with a bilateral high-riding transverse foramen that was treated with rod-screw fixation using a technique of translaminar rigid screw fixation of the axis. It is believed that a C1-2 fixation with bilateral C-2 translaminar screws has an important advantage over previously reported techniques of C1-2 fixation by eliminating the risk of injury to the vertebral artery during C2 screw placement.

The Prevention and Management of the Complications of translaminar Microendoscopic Discectomy / 中国微创外科杂志

Objective To study the complications of translaminar microendoscopic discectomy and their prevention and management. Methods The complications of translaminar microendoscopic discectomy performed on 487 cases of lumbar disc herniations were retrospectively analyzed. Results Most of the complications were seen in the first 50 cases, which included intraoperative CSF leak (8 cases, 1.64% ), cauda equina damage (1 case,0.21%) nerve root damage (1 case,0.21%) and inflammation of intervertebral disc (1 case,0.21%). Three patients (0.62%) converted into standard open lumbar disc surgery because epidural bleeding was difficult to control under endoscope. Conclusions There is a direct correlation between the compliations and the clinical experience in this technique. The complications of translaminar microendoscopic discectomy at the early stage are significantly higher than those of open techniques, but they are rarely seen at the later stage.

Effects of Translaminar Approach and Transforaminal Approach in Lumbar Epidural Steroid Injection

OBJECTIVE: The goal of this study was to compare the therapeutic and the functional value between translaminar approach and transforaminal approach of epidural steroid injection in patient with refractory radicular pain. METHOD: Among 31 patients with unilateral herniated nucleus pulposus (HNP) which was confirmed by physical examination and magnetic resonance imaging (MRI), 17 patients received a transforaminal approach and 14 patients received a translaminar approach. All patients were evaluated by independent observer and were checked by visual analogue scale (VAS), functional score before and 1 day, 2 weeks and 4 weeks after injection. RESULTS: The VAS of transforaminal approach was significantly lower than that of translaminar approach after 2 weeks and after 4 weeks (p<0.05), although there were no statistical difference before and 1 day after injection. The functional score of transforaminal approach was significantly higher than that of translaminar approach after 4 weeks (p<0.05), although there were no statistical difference before and 1 day, 2 weeks after injection. The translaminar approach needs more frequent injection (p<0.05). CONCLUSION: This study suggests that both translaminar approach and transforaminal approach could be valuable to the initial management of refractory radicular pain, but the duration of therapeutic effects was relatively short in translaminar approach. Transforaminal approach will be the promising treatment of refractory radicular pain, because it has better therapeutic efficacy, safety and longer duration of therapeutic effects than translaminar approach.

Translaminar Facet Screw Fixation in Lumbar Spine Fusion / 대한정형외과학회잡지

Between January 1994 and February 1996 lumbar fusion was carried out in eight patients who had degenerative lumbar disease by a technique of translaminar facet screw fixation. The goal of instrumentation is to confer immediate stability to unstable segments and lower the pseudarthrosis rate. However, transpedicular systems can carry a risk of neural damage and require a high standard surgical skills. Therefore, the purpose of this study was to determine the efficacy and safety, and to introduce the simple fusion technique. We usually used this technique for the patients who had been planned single level fusion without definite preoperative instability. Preoperative diagnosis were isthmic spondylolisthesis in one, spinal stenosis in three and laterally herniated lumbar discs in four in which postoperative instability was expected without performing fusion. A single-level fusion was perfomed in all patients. Fusion levels were L2-3 in two, L3-4 in one, L4-5 in four and L5-Sl in one. The average follow-up period was 20 months, ranging from 12 to 36 months. Overall clinical satisfaction including excellent and good result was obtained in all cases. The fusion rate was evaluated radiographically and all were solidly fused. The time to fusion ranged from 3 to 10 months at an average of 5.4 months. There were no significant complications including nerve root injury, and screw loosening or breakage. Although this study was retrospective and the number of cases were small, translaminar facet screw fixation for degenerative lumbar disease is simple and readily available, and provides sufficient rigid stabilization.