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Bone & Joint Open
Vol. 5, Issue 9 | Pages 809 - 817
27 Sep 2024
Altorfer FCS Kelly MJ Avrumova F Burkhard MD Sneag DB Chazen JL Tan ET Lebl DR

Aims

To report the development of the technique for minimally invasive lumbar decompression using robotic-assisted navigation.

Methods

Robotic planning software was used to map out bone removal for a laminar decompression after registration of CT scan images of one cadaveric specimen. A specialized acorn-shaped bone removal robotic drill was used to complete a robotic lumbar laminectomy. Post-procedure advanced imaging was obtained to compare actual bony decompression to the surgical plan. After confirming accuracy of the technique, a minimally invasive robotic-assisted laminectomy was performed on one 72-year-old female patient with lumbar spinal stenosis. Postoperative advanced imaging was obtained to confirm the decompression.


Bone & Joint Open
Vol. 5, Issue 8 | Pages 662 - 670
9 Aug 2024
Tanaka T Sasaki M Katayanagi J Hirakawa A Fushimi K Yoshii T Jinno T Inose H

Aims

The escalating demand for medical resources to address spinal diseases as society ages is an issue that requires careful evaluation. However, few studies have examined trends in spinal surgery, especially unscheduled hospitalizations or surgeries performed after hours, through large databases. Our study aimed to determine national trends in the number of spine surgeries in Japan. We also aimed to identify trends in after-hours surgeries and unscheduled hospitalizations and their impact on complications and costs.

Methods

We retrospectively investigated data extracted from the Diagnosis Procedure Combination database, a representative inpatient database in Japan. The data from April 2010 to March 2020 were used for this study. We included all patients who had undergone any combination of laminectomy, laminoplasty, discectomy, and/or spinal arthrodesis.


Bone & Joint Open
Vol. 5, Issue 7 | Pages 612 - 620
19 Jul 2024
Bada ES Gardner AC Ahuja S Beard DJ Window P Foster NE

Aims

People with severe, persistent low back pain (LBP) may be offered lumbar spine fusion surgery if they have had insufficient benefit from recommended non-surgical treatments. However, National Institute for Health and Care Excellence (NICE) 2016 guidelines recommended not offering spinal fusion surgery for adults with LBP, except as part of a randomized clinical trial. This survey aims to describe UK clinicians’ views about the suitability of patients for such a future trial, along with their views regarding equipoise for randomizing patients in a future clinical trial comparing lumbar spine fusion surgery to best conservative care (BCC; the FORENSIC-UK trial).

Methods

An online cross-sectional survey was piloted by the multidisciplinary research team, then shared with clinical professional groups in the UK who are involved in the management of adults with severe, persistent LBP. The survey had seven sections that covered the demographic details of the clinician, five hypothetical case vignettes of patients with varying presentations, a series of questions regarding the preferred management, and whether or not each clinician would be willing to recruit the example patients into future clinical trials.


The Bone & Joint Journal
Vol. 106-B, Issue 7 | Pages 705 - 712
1 Jul 2024
Karlsson T Försth P Öhagen P Michaëlsson K Sandén B

Aims

We compared decompression alone to decompression with fusion surgery for lumbar spinal stenosis, with or without degenerative spondylolisthesis (DS). The aim was to evaluate if five-year outcomes differed between the groups. The two-year results from the same trial revealed no differences.

Methods

The Swedish Spinal Stenosis Study was a multicentre randomized controlled trial with recruitment from September 2006 to February 2012. A total of 247 patients with one- or two-level central lumbar spinal stenosis, stratified by the presence of DS, were randomized to decompression alone or decompression with fusion. The five-year Oswestry Disability Index (ODI) was the primary outcome. Secondary outcomes were the EuroQol five-dimension questionnaire (EQ-5D), visual analogue scales for back and leg pain, and patient-reported satisfaction, decreased pain, and increased walking distance. The reoperation rate was recorded.


The Bone & Joint Journal
Vol. 106-B, Issue 1 | Pages 53 - 61
1 Jan 2024
Buckland AJ Huynh NV Menezes CM Cheng I Kwon B Protopsaltis T Braly BA Thomas JA

Aims. The aim of this study was to reassess the rate of neurological, psoas-related, and abdominal complications associated with L4-L5 lateral lumbar interbody fusion (LLIF) undertaken using a standardized preoperative assessment and surgical technique. Methods. This was a multicentre retrospective study involving consecutively enrolled patients who underwent L4-L5 LLIF by seven surgeons at seven institutions in three countries over a five-year period. The demographic details of the patients and the details of the surgery, reoperations and complications, including femoral and non-femoral neuropraxia, thigh pain, weakness of hip flexion, and abdominal complications, were analyzed. Neurological and psoas-related complications attributed to LLIF or posterior instrumentation and persistent symptoms were recorded at one year postoperatively. Results. A total of 517 patients were included in the study. Their mean age was 65.0 years (SD 10.3) and their mean BMI was 29.2 kg/m. 2. (SD 5.5). A mean of 1.2 levels (SD 0.6) were fused with LLIF, and a mean of 1.6 (SD 0.9) posterior levels were fused. Femoral neuropraxia occurred in six patients (1.2%), of which four (0.8%) were LLIF-related and two (0.4%) had persistent symptoms one year postoperatively. Non-femoral neuropraxia occurred in nine patients (1.8%), one (0.2%) was LLIF-related and five (1.0%) were persistent at one year. All LLIF-related neuropraxias resolved by one year. A total of 32 patients (6.2%) had thigh pain, 31 (6.0%) were LLIF-related and three (0.6%) were persistent at one year. Weakness of hip flexion occurred in 14 patients (2.7%), of which eight (1.6%) were LLIF-related and three (0.6%) were persistent at one year. No patients had bowel injury, three (0.6%) had an intraoperative vascular injury (not LLIF-related), and five (1.0%) had ileus. Reoperations occurred in five patients (1.0%) within 30 days, 37 (7.2%) within 90 days, and 41 (7.9%) within one year postoperatively. Conclusion. LLIF involving the L4-L5 disc level has a low rate of persistent neurological, psoas-related, and abdominal complications in patients with the appropriate indications and using a standardized surgical technique. Cite this article: Bone Joint J 2024;106-B(1):53–61


Bone & Joint Open
Vol. 4, Issue 8 | Pages 573 - 579
8 Aug 2023
Beresford-Cleary NJA Silman A Thakar C Gardner A Harding I Cooper C Cook J Rothenfluh DA

Aims

Symptomatic spinal stenosis is a very common problem, and decompression surgery has been shown to be superior to nonoperative treatment in selected patient groups. However, performing an instrumented fusion in addition to decompression may avoid revision and improve outcomes. The aim of the SpInOuT feasibility study was to establish whether a definitive randomized controlled trial (RCT) that accounted for the spectrum of pathology contributing to spinal stenosis, including pelvic incidence-lumbar lordosis (PI-LL) mismatch and mobile spondylolisthesis, could be conducted.

Methods

As part of the SpInOuT-F study, a pilot randomized trial was carried out across five NHS hospitals. Patients were randomized to either spinal decompression alone or spinal decompression plus instrumented fusion. Patient-reported outcome measures were collected at baseline and three months. The intended sample size was 60 patients.


The Bone & Joint Journal
Vol. 105-B, Issue 5 | Pages 543 - 550
1 May 2023
Abel F Avrumova F Goldman SN Abjornson C Lebl DR

Aims

The aim of this study was to assess the accuracy of pedicle screw placement, as well as intraoperative factors, radiation exposure, and complication rates in adult patients with degenerative disorders of the thoracic and lumbar spines who have undergone robotic-navigated spinal surgery using a contemporary system.

Methods

The authors reviewed the prospectively collected data on 196 adult patients who had pedicle screws implanted with robot-navigated assistance (RNA) using the Mazor X Stealth system between June 2019 and March 2022. Pedicle screws were implanted by one experienced spinal surgeon after completion of a learning period. The accuracy of pedicle screw placement was determined using intraoperative 3D fluoroscopy.


The Bone & Joint Journal
Vol. 105-B, Issue 4 | Pages 422 - 430
15 Mar 2023
Riksaasen AS Kaur S Solberg TK Austevoll I Brox J Dolatowski FC Hellum C Kolstad F Lonne G Nygaard ØP Ingebrigtsen T

Aims

Repeated lumbar spine surgery has been associated with inferior clinical outcomes. This study aimed to examine and quantify the impact of this association in a national clinical register cohort.

Methods

This is a population-based study from the Norwegian Registry for Spine surgery (NORspine). We included 26,723 consecutive cases operated for lumbar spinal stenosis or lumbar disc herniation from January 2007 to December 2018. The primary outcome was the Oswestry Disability Index (ODI), presented as the proportions reaching a patient-acceptable symptom state (PASS; defined as an ODI raw score ≤ 22) and ODI raw and change scores at 12-month follow-up. Secondary outcomes were the Global Perceived Effect scale, the numerical rating scale for pain, the EuroQoL five-dimensions health questionnaire, occurrence of perioperative complications and wound infections, and working capability. Binary logistic regression analysis was conducted to examine how the number of previous operations influenced the odds of not reaching a PASS.


The Bone & Joint Journal
Vol. 104-B, Issue 12 | Pages 1343 - 1351
1 Dec 2022
Karlsson T Försth P Skorpil M Pazarlis K Öhagen P Michaëlsson K Sandén B

Aims

The aims of this study were first, to determine if adding fusion to a decompression of the lumbar spine for spinal stenosis decreases the rate of radiological restenosis and/or proximal adjacent level stenosis two years after surgery, and second, to evaluate the change in vertebral slip two years after surgery with and without fusion.

Methods

The Swedish Spinal Stenosis Study (SSSS) was conducted between 2006 and 2012 at five public and two private hospitals. Six centres participated in this two-year MRI follow-up. We randomized 222 patients with central lumbar spinal stenosis at one or two adjacent levels into two groups, decompression alone and decompression with fusion. The presence or absence of a preoperative spondylolisthesis was noted. A new stenosis on two-year MRI was used as the primary outcome, defined as a dural sac cross-sectional area ≤ 75 mm2 at the operated level (restenosis) and/or at the level above (proximal adjacent level stenosis).


The Bone & Joint Journal
Vol. 102-B, Issue 12 | Pages 1717 - 1722
1 Dec 2020
Kang T Park SY Lee JS Lee SH Park JH Suh SW

Aims. As the population ages and the surgical complexity of lumbar spinal surgery increases, the preoperative stratification of risk becomes increasingly important. Understanding the risks is an important factor in decision-making and optimizing the preoperative condition of the patient. Our aim was to determine whether the modified five-item frailty index (mFI-5) and nutritional parameters could be used to predict postoperative complications in patients undergoing simple or complex lumbar spinal fusion. Methods. We retrospectively reviewed 584 patients who had undergone lumbar spinal fusion for degenerative lumbar spinal disease. The 'simple' group (SG) consisted of patients who had undergone one- or two-level posterior lumbar fusion. The 'complex' group (CG) consisted of patients who had undergone fusion over three or more levels, or combined anterior and posterior surgery. On admission, the mFI-5 was calculated and nutritional parameters collected. Results. Complications occurred in 9.3% (37/396) of patients in the SG, and 10.1% (19/167) of patients in the CG. In the SG, the important predictors of complications were age (odds ratio (OR) 1.036; p = 0.002); mFI-5 (OR 1.026 to 2.411, as score increased to 1 ≥ 2 respectively. ;. p = 0.023); albumin (OR 11.348; p < 0.001); vitamin D (OR 2.185; p = 0.032); and total lymphocyte count (OR 1.433; p = 0.011) . In the CG, the predictors of complications were albumin (OR 9.532; p = 0.002) and vitamin D (OR 3.815; p = 0.022). Conclusion. The mFI-5 and nutritional status were effective predictors of postoperative complications in the SG, but only nutritional status was successful in predicting postoperative complications in the CG. The complexity of the surgery, as well as the preoperative frailty and nutritional status of patients, should be considered when determining if it is safe to proceed with lumbar spinal fusion. Cite this article: Bone Joint J 2020;102-B(12):1717–1722


The Bone & Joint Journal
Vol. 102-B, Issue 8 | Pages 1062 - 1071
1 Aug 2020
Cheung JPY Fong HK Cheung PWH

Aims. To determine the effectiveness of prone traction radiographs in predicting postoperative slip distance, slip angle, changes in disc height, and lordosis after surgery for degenerative spondylolisthesis of the lumbar spine. Methods. A total of 63 consecutive patients with a degenerative spondylolisthesis and preoperative prone traction radiographs obtained since 2010 were studied. Slip distance, slip angle, disc height, segmental lordosis, and global lordosis (L1 to S1) were measured on preoperative lateral standing radiographs, flexion-extension lateral radiographs, prone traction lateral radiographs, and postoperative lateral standing radiographs. Patients were divided into two groups: posterolateral fusion or posterolateral fusion with interbody fusion. Results. The mean changes in segmental lordosis and global lordosis were 7.1° (SD 6.7°) and 2.9° (SD 9.9°) respectively for the interbody fusion group, and 0.8° (SD 5.1°) and -0.4° (SD 10.1°) respectively for the posterolateral fusion-only group. Segmental lordosis (ρ = 0.794, p < 0.001) corrected by interbody fusion correlated best with prone traction radiographs. Global lumbar lordosis (ρ = 0.788, p < 0.001) correlated best with the interbody fusion group and preoperative lateral standing radiographs. The least difference in slip distance (-0.3 mm (SD 1.7 mm), p < 0.001), slip angle (0.9° (SD 5.2°), p < 0.001), and disc height (0.02 mm (SD 2.4 mm), p < 0.001) was seen between prone traction and postoperative radiographs. Regression analyses suggested that prone traction parameters best predicted correction of slip distance (Corrected Akaike’s Information Criterion (AICc) = 37.336) and disc height (AICc = 58.096), while correction of slip angle (AICc = 26.453) was best predicted by extension radiographs. Receiver operating characteristic (ROC) cut-off showed, with 68.3% sensitivity and 64.5% specificity, that to achieve a 3.0° increase in segmental lordotic angle, patients with a prone traction disc height of 8.5 mm needed an interbody fusion. Conclusion. Prone traction radiographs best predict the slip distance and disc height correction achieved by interbody fusion for lumbar degenerative spondylolisthesis. To achieve this maximum correction, interbody fusion should be undertaken if a disc height of more than 8.5 mm is attained on preoperative prone traction radiographs. Level of Evidence: Level II Prognostic Study. Cite this article: Bone Joint J 2020;102-B(8):1062–1071


The Bone & Joint Journal
Vol. 101-B, Issue 12 | Pages 1526 - 1533
1 Dec 2019
Endler P Ekman P Berglund I Möller H Gerdhem P

Aims

Chronic low back pain due to degenerative disc disease is sometimes treated with fusion. We compared the outcome of three different fusion techniques in the Swedish Spine Register: noninstrumented posterolateral fusion (PLF), instrumented posterolateral fusion (IPLF), and interbody fusion (IBF).

Patients and Methods

A total of 2874 patients who were operated on at one or two lumbar levels were followed for a mean of 9.2 years (3.6 to 19.1) for any additional lumbar spine surgery. Patient-reported outcome data were available preoperatively (n = 2874) and at one year (n = 2274), two years (n = 1958), and a mean of 6.9 years (n = 1518) postoperatively and consisted of global assessment and visual analogue scales of leg and back pain, Oswestry Disability Index, EuroQol five-dimensional index, 36-Item Short-Form Health Survey, and satisfaction with treatment. Statistical analyses were performed with competing-risks proportional hazards regression or analysis of covariance, adjusted for baseline variables.


The Bone & Joint Journal
Vol. 101-B, Issue 9 | Pages 1115 - 1121
1 Sep 2019
Takenaka S Makino T Sakai Y Kashii M Iwasaki M Yoshikawa H Kaito T

Aims

The aim of this study was to explore risk factors for complications associated with dural tear (DT), including the types of DT, and the intra- and postoperative management of DT.

Patients and Methods

Between 2012 and 2017, 12 171 patients with degenerative lumbar diseases underwent primary lumbar spine surgery. We investigated five categories of potential predictors: patient factors (sex, age, body mass index, and primary disease), surgical factors (surgical procedures, operative time, and estimated blood loss), types of DT (inaccessible for suturing/clipping and the presence of cauda equina/nerve root herniation), repair techniques (suturing, clipping, fibrin glue, polyethylene glycol (PEG) hydrogel, and polyglycolic acid sheet), and postoperative management (drainage duration). Postoperative complications were evaluated in terms of dural leak, prolonged bed rest, headache, nausea/vomiting, delayed wound healing, postoperative neurological deficit, surgical site infection (SSI), and reoperation for DT. We performed multivariable regression analyses to evaluate the predictors of postoperative complications associated with DT.


The Bone & Joint Journal
Vol. 100-B, Issue 4 | Pages 499 - 506
1 Apr 2018
Minamide A Yoshida M Simpson AK Nakagawa Y Iwasaki H Tsutsui S Takami M Hashizume H Yukawa Y Yamada H

Aims

The aim of this study was to investigate the clinical and radiographic outcomes of microendoscopic laminotomy in patients with lumbar stenosis and concurrent degenerative spondylolisthesis (DS), and to determine the effect of this procedure on spinal stability.

Patients and Methods

A total of 304 consecutive patients with single-level lumbar DS with concomitant stenosis underwent microendoscopic laminotomy without fusion between January 2004 and December 2010. Patients were divided into two groups, those with and without advanced DS based on the degree of spondylolisthesis and dynamic instability. A total of 242 patients met the inclusion criteria. There were 101 men and 141 women. Their mean age was 68.1 years (46 to 85). Outcome was assessed using the Japanese Orthopaedic Association and Roland Morris Disability Questionnaire scores, a visual analogue score for pain and the Short Form Health-36 score. The radiographic outcome was assessed by measuring the slip and the disc height. The clinical and radiographic parameters were evaluated at a mean follow-up of 4.6 years (3 to 7.5).


Bone & Joint Research
Vol. 7, Issue 1 | Pages 28 - 35
1 Jan 2018
Huang H Nightingale RW Dang ABC

Objectives. Loss of motion following spine segment fusion results in increased strain in the adjacent motion segments. However, to date, studies on the biomechanics of the cervical spine have not assessed the role of coupled motions in the lumbar spine. Accordingly, we investigated the biomechanics of the cervical spine following cervical fusion and lumbar fusion during simulated whiplash using a whole-human finite element (FE) model to simulate coupled motions of the spine. Methods. A previously validated FE model of the human body in the driver-occupant position was used to investigate cervical hyperextension injury. The cervical spine was subjected to simulated whiplash exposure in accordance with Euro NCAP (the European New Car Assessment Programme) testing using the whole human FE model. The coupled motions between the cervical spine and lumbar spine were assessed by evaluating the biomechanical effects of simulated cervical fusion and lumbar fusion. Results. Peak anterior longitudinal ligament (ALL) strain ranged from 0.106 to 0.382 in a normal spine, and from 0.116 to 0.399 in a fused cervical spine. Strain increased from cranial to caudal levels. The mean strain increase in the motion segment immediately adjacent to the site of fusion from C2-C3 through C5-C6 was 26.1% and 50.8% following single- and two-level cervical fusion, respectively (p = 0.03, unpaired two-way t-test). Peak cervical strains following various lumbar-fusion procedures were 1.0% less than those seen in a healthy spine (p = 0.61, two-way ANOVA). Conclusion. Cervical arthrodesis increases peak ALL strain in the adjacent motion segments. C3-4 experiences greater changes in strain than C6-7. Lumbar fusion did not have a significant effect on cervical spine strain. Cite this article: H. Huang, R. W. Nightingale, A. B. C. Dang. Biomechanics of coupled motion in the cervical spine during simulated whiplash in patients with pre-existing cervical or lumbar spinal fusion: A Finite Element Study. Bone Joint Res 2018;7:28–35. DOI: 10.1302/2046-3758.71.BJR-2017-0100.R1


The Bone & Joint Journal
Vol. 99-B, Issue 10 | Pages 1366 - 1372
1 Oct 2017
Rickert M Fleege C Tarhan T Schreiner S Makowski MR Rauschmann M Arabmotlagh M

Aims. We compared the clinical and radiological outcomes of using a polyetheretherketone cage with (TiPEEK) and without a titanium coating (PEEK) for instrumented transforaminal lumbar interbody fusion (TLIF). Materials and Methods. We conducted a randomised clinical pilot trial of 40 patients who were scheduled to undergo a TLIF procedure at one or two levels between L2 and L5. The Oswestry disability index (ODI), EuroQoL-5D, and back and leg pain were determined pre-operatively, and at three, six, and 12 months post-operatively. Fusion rates were assessed by thin slice CT at three months and by functional radiography at 12 months. Results. At final follow-up, one patient in each group had been lost to follow-up. Two patients in each of the PEEK and TiPEEK groups were revised for pseudarthrosis (p = 1.00). The rate of complete or partial fusion at three months was 91.7% in both groups. Overall, there were no significant differences in ODI or in radiological outcomes between the groups. Conclusion. Favourable results with identical clinical outcomes and a high rate of fusion was seen in both groups. The titanium coating appears to have no negative effects on outcome or safety in the short term. A future study to determine the effect of titanium coating is warranted. Cite this article: Bone Joint J 2017;99-B:1366–72


The Bone & Joint Journal
Vol. 99-B, Issue 9 | Pages 1204 - 1209
1 Sep 2017
Fawi HMT Saba K Cunningham A Masud S Lewis M Hossain M Chopra I Ahuja S

Aims

To evaluate the incidence of primary venous thromboembolism (VTE), epidural haematoma, surgical site infection (SSI), and 90-day mortality after elective spinal surgery, and the effect of two protocols for prophylaxis.

Patients and Methods

A total of 2181 adults underwent 2366 elective spinal procedures between January 2007 and January 2012. All patients wore anti-embolic stockings, mobilised early and were kept adequately hydrated. In addition, 29% (689) of these were given low molecular weight heparin (LMWH) while in hospital. SSI surveillance was undertaken using the Centers for Disease Control and Prevention criteria.


The Bone & Joint Journal
Vol. 99-B, Issue 8 | Pages 1003 - 1005
1 Aug 2017
Todd NV

The National Institute for Health and Care Excellence has issued guidelines that state fusion for non-specific low back pain should only be performed as part of a randomised controlled trial, and that lumbar disc replacement should not be performed. Thus, spinal fusion and disc replacement will no longer be routine forms of treatment for patients with low back pain. This annotation considers the evidence upon which these guidelines are based.

Cite this article: Bone Joint J 2017;99-B:1003–1005.


The Bone & Joint Journal
Vol. 99-B, Issue 7 | Pages 944 - 950
1 Jul 2017
Fan G Fu Q Zhang J Zhang H Gu X Wang C Gu G Guan X Fan Y He S

Aims. Minimally invasive transforaminal lumbar interbody fusion (MITLIF) has been well validated in overweight and obese patients who are consequently subject to a higher radiation exposure. This prospective multicentre study aimed to investigate the efficacy of a novel lumbar localisation system for MITLIF in overweight patients. Patients and Methods. The initial study group consisted of 175 patients. After excluding 49 patients for various reasons, 126 patients were divided into two groups. Those in Group A were treated using the localisation system while those in Group B were treated by conventional means. The primary outcomes were the effective radiation dosage to the surgeon and the exposure time. Results. There were 62 patients in Group A and 64 in Group B. The mean effective dosage was 0.0217 mSv (standard deviation (. sd. ) 0.0079) in Group A and 0.0383 mSv (. sd. 0.0104) in Group B (p <  0.001). The mean fluoroscopy exposure time was 26.42 seconds (. sd. 5.91) in Group A and 40.67 seconds (. sd. 8.18) in Group B (p < 0.001). The operating time was 175.56 minutes (. sd. 32.23) and 206.08 minutes (. sd. 30.15) (p < 0.001), respectively. The mean pre-operative localisation time was 4.73 minutes (. sd. 0.84) in Group A and 7.03 minutes (. sd. 1.51) in Group B (p < 0.001). The mean screw placement time was 47.37 minutes (. sd. 10.43) in Group A and 67.86 minutes (. sd. 14.15) in Group B (p < 0.001). The pedicle screw violation rate was 0.35% (one out of 283) in Group A and 2.79% (eight out of 287) in Group B (p = 0.020). Conclusion. The study shows that the localisation system can effectively reduce radiation exposure, exposure time, operating time, pre-operative localisation time, and screw placement time in overweight patients undergoing MITLIF. Cite this article: Bone Joint J 2017;99-B:944–50


Bone & Joint Research
Vol. 6, Issue 4 | Pages 245 - 252
1 Apr 2017
Fu M Ye Q Jiang C Qian L Xu D Wang Y Sun P Ouyang J

Objectives

Many studies have investigated the kinematics of the lumbar spine and the morphological features of the lumbar discs. However, the segment-dependent immediate changes of the lumbar intervertebral space height during flexion-extension motion are still unclear. This study examined the changes of intervertebral space height during flexion-extension motion of lumbar specimens.

Methods

First, we validated the accuracy and repeatability of a custom-made mechanical loading equipment set-up. Eight lumbar specimens underwent CT scanning in flexion, neural, and extension positions by using the equipment set-up. The changes in the disc height and distance between adjacent two pedicle screw entry points (DASEP) of the posterior approach at different lumbar levels (L3/4, L4/5 and L5/S1) were examined on three-dimensional lumbar models, which were reconstructed from the CT images.