Adjacent Segment Disease Research Articles

Lumbar Arthroplasty is Associated with a Lower Incidence of Adjacent Segment Disease Compared to ALIF: A Propensity Matched Analysis.

Retrospective Cohort Study. To compare the rate of ASD between lumbar disc arthroplasty (LDA) and anterior lumbar interbody fusion (ALIF). Lumbar disc arthroplasty (LDA) and anterior lumbar interbody fusion (ALIF) are alternative surgical approaches used to treat lumbar degenerative disc disease. However, there is a paucity of studies comparing the risk of adjacent segment disease (ASD) following these procedures. Patients who underwent 1-2 level LDA or ALIF between 2010 and 2022 were identified in the PearlDiver Mariner insurance all-claims database. Exclusion criteria included history of prior lumbar spine surgery, or surgery for tumors, trauma, or infection. 1:1 propensity matching was performed using demographic factors, medical comorbidities, and surgical factors which were significantly associated with ASD. 1:1 Propensity matching created two equal groups of 1,625 patients without baseline differences who underwent LDA or ALIF. LDA was significantly associated with a lower risk of ASD (RR 0.932, 95% CI 0.899-0.967, P<0.001), and need for revision within 30 days (RR 0.235, 95% CI 0.079-0.698, P=0.007). There were no differences in all-cause surgical and medical complications between both groups. After risk adjustment for demographic and clinical characteristics, the results suggest that LDA is associated with a lower risk of adjacent segment disease compared to ALIF. LDA was also associated with lower hospital cost and shorter length of stay.

The anatomic study and surgical technique for canal decompression with “pedicle-plasty” strategy in lumbar burst fractures with pedicle rupture

ABSTRACT In the treatment of lumbar burst fractures with nerve injury, fusion is often required to rebuild spinal stability, but it can lead to the loss of motor units and increase the occurrence of adjacent segment diseases. Thus, a novel approach of lumbar canal decompression with “pedicle-plasty” strategy (DDP) was needed in clincal treatment. Firstly, image measurement analysis, the images of 60 patients with lumbar spine CT examinations were selected to measure osteotomy angle (OA), distance from the intersection of osteotomy plane and skin to the posterior midline (DM),transverse length of the osteotomy plane (TLOP), and sagittal diameter of the outer edge of superior articular process (SD). Secondary, cadaver study, distance between the intermuscular space and midline (DMSM), anterior and posterior diameters of the decompression (APDD), and lateral traction distance of the lumbosacral plexus (TDLP) were measured on 10 cadaveric specimens. Finally, procedure of DDP was demonstrated on cadaver specimens. OA ranged from 27.68°+4.59° to 38.34°+5.97°, DM ranged from 43.44+6.29 to 68.33+12.06 mm, TLOP ranged from 16.84+2.19 to 19.64+2.36 mm, and SD ranged from 22.49+1.74 to 25.53+2.21 mm. DMSM ranged from 45.53+5.73 to 65.46+6.43 mm. APDD were between 10.51+3.59 and 12.12+4.54 mm, and TDLP were between 3.28+0.81 and 6.27+0.62 mm.DDP was successfully performed on cadaveric specimens. DDP, as a novel approach of decompression of burst fractures with pedicle rupture, can fully relieve the occupation and at the same time preserve the spinal motor unit because of no resection of intervertebral discs and no destruction of facet joints,and has certain developmental significance.

Spine

The April 2023 Spine Roundup360 looks at: Percutaneous transforaminal endoscopic discectomy versus microendoscopic discectomy; Spine surgical site infections: a single debridement is not enough; Lenke type 5, anterior, or posterior: systematic review and meta-analysis; Epidural steroid injections and postoperative infection in lumbar decompression or fusion; Noninferiority of posterior cervical foraminotomy versus anterior cervical discectomy; Identifying delays to surgical treatment for metastatic disease; Cervical disc replacement and adjacent segment disease: the NECK trial; Predicting complication in adult spine deformity surgery.

356 Intraoperative Robotic Planning Software is Accurate at Predicting Postoperative Lumbar Lordosis After Anterior Column Reconstruction

INTRODUCTION: Re-establishment of lumbar lordosis with spine deformity surgery is considered a pre-requisite for long term positive results with less biomechanical loading on the adjacent segments, reducing the likelihood of developing adjacent segment disease. The pre-operative planning softwares of robotic systems now allow the surgeon to plan a patient-specific surgical plan and are also able to predict the degree of lumbar lordosis following the instrumentation surgery based on pre-operative imaging by using vertebral segmentation. METHODS: We conducted a retrospective review of patients aged 18 or older who underwent pedicle screw spinal instrumentation using the Mazor X Robot (Medtronic Inc., Minneapolis, MN, USA), performed by one surgeon over a five-year period. The robotic guidance software (Mazor X-Align, Medtronic Inc., Minneapolis, MN, USA) was used to calculate the predicted lumbar lordosis based on pre-operative imaging. Wilcoxon Rank test was used to compare the predicted angles to the observed lumbar lordosis on post-operative radiographs. RESULTS: A total of 15 patients (46.6% female) with a mean age of 61.5 ± 10.9 years were identified, who underwent posterior lumbo-sacral spinal fusion with the robotic system using both percutaneous and open approach. Instrumentation was done across a mean of 3.27 levels per case and 11 patients (73.3%) underwent anterior column reconstruction prior to posterior fixation without the need for an intra-operative CT spin. There was no statistical difference between the predicted and the actual post-operative lumbar lordosis (p-value: 0.334) while there was a significant statistical difference between the pre-operative and post-operative angles (p-value: 0.02). CONCLUSIONS: Our study suggests that the intraoperative robotic planning software of the Mazor X system is accurate at predicting postoperative lumbar lordosis which can be useful and help guide surgical decision making and planning.

Up to 10-year surveillance comparison of survivability in single-level cervical disc replacement versus anterior cervical discectomy and fusion in New York.

Cervical disc replacement (CDR) is an alternative treatment to anterior cervical discectomy and fusion (ACDF), which is the current gold standard, for degenerative cervical diseases such as cervical spondylotic myelopathy and cervical radiculopathy. CDR has several theoretical benefits over ACDF, including preservation of motion, earlier return to unrestricted activity, and potentially a lower risk of adjacent-segment disease. Recent literature has reported positive clinical results for CDR, but few studies have investigated the long-term risk of revision surgery of CDR versus ACDF. The purpose of this study was to identify and analyze the epidemiological, clinical, and operative risk factors that affect revision rates following single-level CDR and ACDF procedures. A retrospective cohort was extracted from the Statewide Planning and Research Cooperative System using ICD-9 and CPT codes. Inclusion criteria were adult patients undergoing primary, subaxial (C3-7), single-level ACDF or CDR for cervical radiculopathy and/or cervical spondylotic myelopathy between 2005 and 2013. Survivability was defined as the time between the index procedure and the presence of a subsequent discharge record for cervical spinal fusion or disc replacement. Statistical analyses were performed using chi-square tests, t-tests, Cox proportional hazards models, and a Kaplan-Meier plot. A total of 7450 patients were included in this study (6615 ACDF and 835 CDR). When adjusted for patient demographics, the hazard ratios showed no significant differences in the incidence of revision risk between the two cohorts. The CDR cohort had a higher incidence of postoperative dysphagia (p < 0.05). Patients undergoing ACDF had a longer average hospital stay (2.8 vs 1.9 days, p < 0.001). There was no significant difference in time to revision surgery (p = 0.486). CDR and ACDF have both been shown to be effective treatments for cervical spine disease. CDR patients had a shorter average inpatient hospital stay compared with ACDF patients but tended to experience dysphagia more frequently. There was a tendency toward increased survivability of CDR; however, this was not found to be statistically significant at any time point. The large size and heterogeneity of each cohort and the availability of > 10 years of surveillance data differentiate this study from other published literature. This investigation has limitations inherent to large data analysis studies, including the implementation and inaccuracy of diagnosis and procedural coding; however, this reflects real-world use of coding by practitioners.

Reoperation Rates Due to ASD following Primary 1-2 level MIS vs. Open TLIF.

Retrospective analysis of prospectively collected data. To investigate the effect of the approach of the TLIF (open vs. MIS) on reoperation rates due to ASD at 2 - 4 year follow up. Adjacent segment degeneration (ASDeg) is a complication of lumbar fusion surgery which may progress to adjacent segment disease (ASD) and cause debilitating postoperative pain potentially requiring additional operative management for relief. Minimally invasive (MIS) transforaminal lumbar interbody fusion surgery (TLIF) has been introduced to minimize this complication but the impact on ASD incidence is unclear. For a cohort of patients undergoing 1- or 2-level primary TLIF between 2013 and 2019, patient demographics and follow-up outcomes were collected and compared between patients who underwent open versus MIS TLIF using Mann Whitney U test, Fischer's exact test, and binary logistic regression. 238 patients met inclusion criteria. There was a significant difference in revision rates due to ASD between MIS and open TLIFs at 2 (5.8% vs. 15.4%, P=0.021) and 3 (8% vs. 23.2%, P=0.03) year follow up, with open TLIFs demonstrating significantly higher revision rates. Surgical approach was the only independent predictor of reoperation rates at both 2 and 3 year follow ups (2-year P=0.009; 3-year P=0.011). Open TLIF was found to have a significantly higher rate of reoperation due to ASD compared to the MIS approach. Additionally, surgical approach (MIS vs. Open) appears to be an independent predictor of reoperation rates.

A real-world analysis of hybrid CDA and ACDF compared to multilevel ACDF

BackgroundMultilevel anterior cervical discectomy and fusion (mACDF) is the gold standard for multilevel spinal disease; although safe and effective, mACDF can limit regular spinal motion and contribute to adjacent segment disease (ASD). Hybrid surgery, composed of ACDF and cervical disc arthroplasty, has the potential to reduce ASD by retaining spinal mobility. This study examined the safety of hybrid surgery by utilizing administrative claims data to compare real-world rates of subsequent surgery and post-procedural hospitalization within populations of patients undergoing hybrid surgery versus mACDF for multilevel spinal disease.MethodsThis observational, retrospective analysis used the MarketScan Commercial and Medicare Database from July 2013 through June 2020. Propensity score matched cohorts of patients who received hybrid surgery or mACDF were established based on the presence of spinal surgery procedure codes in the claims data and followed over a variable post-period. Rates of subsequent surgery and post-procedural hospitalization (30- and 90-day) were compared between hybrid surgery and mACDF cohorts.ResultsA total of 430 hybrid surgery patients and 2,136 mACDF patients qualified for the study; average follow-up was approximately 2 years. Similar rates of subsequent surgery (Hybrid: 1.9 surgeries/100 patient-years; mACDF: 1.8 surgeries/100 patient-years) were observed for the two cohorts. Hospitalization rates were also similar across cohorts at 30 days post-procedure (Hybrid: 0.67% hospitalized/patient-year; mACDF: 0.87% hospitalized/patient-year). At 90 days post-procedure, hybrid surgery patients had slightly lower rates of hospitalization compared to mACDF patients (0.23% versus 0.42% hospitalized/patient-year; p < 0.05).ConclusionsFindings of this real-world, retrospective cohort study confirm prior reports indicating that hybrid surgery is a safe and effective intervention for multilevel spinal disease which demonstrates non-inferiority in relation to the current gold standard mACDF. The use of administrative claims data in this analysis provides a unique perspective allowing the inclusion of a larger, more generalizable population has historically been reported on in small cohort studies.

Research status and existing problems of lumbar pedicle double-trajectory screw technique

Lumbar pedicle double-trajectory screw technique refers to the placement of traditional pedicle screw combined with cortical bone trajectory screw in the same pedicle, which has been proved to provide higher fixation strength in osteoporotic vertebral body fixation, and is also a less invasive surgical choice for revision of adjacent segment disease. At present, related basic research and clinical application exploration of double-trajectory screw technique have been carried out, but there are still many problems that need to be further investigated and clarified. The clinical application and existing problems of double screw technique were discussed in this paper for clinical reference.

Preservation of Motion in Spine Surgery.

The number of spinal procedures and spinal fusions continues to grow. Although fusion procedures have a high success rate, they have inherent risks such as pseudarthrosis and adjacent segment disease. New innovations in spine techniques have sought to eliminate these complications by preserving motion in the spinal column. Several techniques and devices have been developed in the cervical and lumbar spine including cervical laminoplasty, cervical disk ADA, posterior lumbar motion preservation devices, and lumbar disk ADA. In this review, advantages and disadvantages of each technique will be discussed.

Examining degenerative disease adjacent to lumbosacral transitional vertebrae: a retrospective cohort study.

Bertolotti syndrome is a clinical diagnosis given to patients with low-back pain arising from a lumbosacral transitional vertebra (LSTV). While biomechanical studies have demonstrated abnormal torques and range of motion occurring at and above this type of LSTV, the long-term effects of these biomechanical changes on the LSTV adjacent segments are not well understood. This study examined degenerative changes at segments superjacent to the LSTV in patients with Bertolotti syndrome. This study involved a retrospective comparison of patients between 2010 and 2020 with an LSTV and chronic back pain (Bertolotti syndrome) and control patients with chronic back pain with no LSTV. The presence of an LSTV was confirmed on imaging, and the caudal-most mobile segment above the LSTV was assessed for degenerative changes. Degenerative changes were assessed by grading the intervertebral disc, facets, degree of spinal stenosis, and spondylolisthesis using well documented grading systems. All computations were performed in R, version 4.1.0. All tests were two-sided, and p values < 0.05 was considered statistically significant. Separate logistic regression analyses were run with the associated dependent variables for each aim, with age at MRI and sex included as covariates. Odds ratios and 95% confidence intervals were computed. A total of 172 patients were included, 101 with Bertolotti syndrome and 71 controls. Control patients consisted of patients with low-back pain but no diagnosis of Bertolotti syndrome or an LSTV. Fifty-six Bertolotti (55.4%) and 27 control (38.0%) patients were female, (p = 0.03). After adjusting for age at MRI and sex, Bertolotti patients had pelvic incidence (PI) that was 9.83° greater than control patients (95% CI 5.15°-14.50°, p < 0.001). Sacral slope was not significantly different between the Bertolotti and control groups (beta estimate 3.10°, 95% CI -1.07° to 7.27°; p = 0.14). Bertolotti patients had 2.69 times higher odds of having a high disc grade at L4-5 (3-4 vs 0-2), compared with control patients (OR 2.69, 95% CI 1.28-5.90; p = 0.01). There were no significant differences between Bertolotti patients and controls for spondylolisthesis, facet grade, or spinal stenosis grade. Patients with Bertolotti syndrome had a significantly higher PI and were more likely to have adjacent-segment disease (ASD; L4-5) compared with control patients. However, after controlling for age and sex, PI and ASD did not appear to have a significant association within the cohort of Bertolotti patients. The altered biomechanics and kinematics in this condition may be a causative factor in this degeneration, although proof of causation is not possible in this study. This association may warrant closer follow-up protocols for patients being treated for Bertolotti syndrome, but further prospective studies are needed to establish if radiographic parameters can serve as an indicator for biomechanical alterations in vivo.

Medium and long-term radiographic and clinical outcomes of Dynesys dynamic stabilization versus instrumented fusion for degenerative lumbar spine diseases

BackgroundDynesys stabilization (DS) is utilized to preserve mobility at the instrumental segments and prevent adjacent segment pathology in clinical practice. However, the advantages of DS method in medium and long-term follow-up remain controversial.ObjectiveTo compare the radiographic and clinical outcomes between DS and instrumented fusion in the treatment of degenerative lumbar spine disease with or without grade I spondylolisthesis with a minimum follow-up period of 2 years.MethodsWe conducted a comprehensive search of PubMed, EMBASE, Cochrane, and Web of Science databases, Chinese National Knowledge Databases, and Wanfang Database for potentially eligible articles. Clinical outcomes were assessed in terms of VAS and ODI scores, screw loosening and breakage, and surgical revision. Radiographic outcomes were assessed in terms of postoperative range of movement (ROM) and disc heigh. Moreover, adjacent segment degeneration (ASDeg) and adjacent segment disease (ASDis) were evaluated.ResultsSeventeen studies with 1296 patients were included in the meta-analysis. The DS group was associated with significantly lower postoperative VAS scores for low-back and leg pain, and lower rate of surgical revision than the fusion group. Moreover, the Dynesys group showed significantly less ASDeg than the fusion group but showed no significant advantage over the fusion group in terms of preventing ASDis. Additionally, the ROM at the stabilized segments of the fusion group decreased significantly and that at the adjacent segments increased significantly compared with those of the DS group.ConclusionDS showed comparable clinical outcomes and provided benefits in preserving the motion at the stabilized segments, thus limiting the hypermobility at the adjacent segments and preventing ASDeg compared with the fusion method in degenerative disease with or without grade I spondylolisthesis.

Biomechanical evaluation of a novel biomimetic artificial intervertebral disc in canine cervical cadaveric spines.

Cervical disc replacement (CDR) aims to restore motion of the treated level to reduce the risk of adjacent segment disease (ASD) compared with spinal fusion. However, first-generation articulating devices are unable to mimic the complex deformation kinematics of a natural disc. Thus, a biomimetic artificial intervertebral CDR (bioAID), containing a hydroxyethylmethacrylate (HEMA)-sodium methacrylate (NaMA) hydrogel core representing the nucleus pulposus, an ultra-high-molecular-weight-polyethylene fiber jacket as annulus fibrosus, and titanium endplates with pins for primary mechanical fixation, was developed. To assess the initial biomechanical effect of the bioAID on the kinematic behavior of the canine spine, an ex vivo biomechanical study in 6-degrees-of-freedom was performed. A canine cadaveric biomechanical study. Six cadaveric canine specimens (C3-C6) were tested in flexion-extension (FE), lateral bending (LB) axial rotation (AR) using a spine tester in three conditions: intact, after C4-C5 disc replacement with bioAID, and after C4-C5 interbody fusion. A hybrid protocol was used where first the intact spines were subjected to a pure moment of ±1Nm, whereafter the treated spines were subjected to the full range of motion (ROM) of the intact condition. 3D segmental motions at all levels were measured while recording the reaction torsion. Biomechanical parameters studied included ROM, neutral zone (NZ), and intradiscal pressure (IDP) at the adjacent cranial level (C3-C4). The bioAID retained the sigmoid shape of the moment-rotation curves with a NZ similar to the intact condition in LB and FE. Additionally, the normalized ROMs at the bioAID-treated level were statistically equivalent to intact during FE and AR while slightly decreased in LB. At the two adjacent levels, ROMs showed similar values for the intact compared to the bioAID for FE and AR and an increase in LB. In contrast, levels adjacent to the fused segment showed an increased motion in FE and LB as compensation for the loss of motion at the treated level. The IDP at the adjacent C3-C4 level after implantation of bioAID was close to intact values. After fusion, increased IDP was found compared with intact but did not reach statistical significance. This study indicates that the bioAID can mimic the kinematic behavior of the replaced intervertebral disc and preserves that for the adjacent levels better than fusion. As a result, CDR using the novel bioAID is a promising alternative treatment for replacing severely degenerated intervertebral discs.

Comparison of Oblique Lumbar Interbody Fusion Combined with Posterior Decompression (OLIF-PD) and Posterior Lumbar Interbody Fusion (PLIF) in the Treatment of Adjacent Segmental Disease(ASD)

An unintended consequence following lumbar fusion is the development of adjacent segment disease (ASD). Oblique lumbar interbody fusion combined with posterior decompression (OLIF-PD) is another feasible option for ASD, and there is no literature report on this combined surgical strategy. A retrospective analysis was performed on 18 ASD patients requiring direct decompression in our hospital between September 2017 and January 2022. Among them, eight patients underwent OLIF-PD revision and ten underwent PLIF revision. There were no significant differences in the baseline data between the two groups. The clinical outcomes and complications were compared between the two groups. The operation time, operative blood loss and postoperative hospital stay in the OLIF-PD group were significantly lower than those in the PLIF group. The VAS of low back pain in the OLIF-PD group was significantly better than that in the PLIF group during the postoperative follow-up. The ODI at the last follow-up in the OLIF-PD group and the PLIF group were significantly relieved compared with those before operation. The excellent and good rate of the modified MacNab standard at the last follow-up was 87.5% in the OLIF-PD group and 70% in the PLIF group. There was a statistically significant difference in the incidence of complications between the two groups. For ASD requiring direct decompression after posterior lumbar fusion, compared with traditional PLIF revision surgery, OLIF-PD has a similar clinical effect, but has a reduced operation time, blood loss, hospital stay and complications. OLIF-PD may be an alternative revision strategy for ASD.

Anatomical parameters alter the biomechanical responses of adjacent segments following lumbar fusion surgery: Personalized poroelastic finite element modelling investigations.

Introduction: While the short-term post-operative outcome of lumbar fusion is satisfying for most patients, adjacent segment disease (ASD) can be prevalent in long-term clinical observations. It might be valuable to investigate if inherent geometrical differences among patients can significantly alter the biomechanics of adjacent levels post-surgery. This study aimed to utilize a validated geometrically personalized poroelastic finite element (FE) modeling technique to evaluate the alteration of biomechanical response in adjacent segments post-fusion. Methods: Thirty patients were categorized for evaluation in this study into two distinct groups [i.e., 1) non-ASD and 2) ASD patients] based on other long-term clinical follow-up investigations. To evaluate the time-dependent responses of the models subjected to cyclic loading, a daily cyclic loading scenario was applied to the FE models. Different rotational movements in different planes were superimposed using a 10Nm moment after daily loading to compare the rotational motions with those at the beginning of cyclic loading. The biomechanical responses of the lumbosacral FE spine models in both groups were analyzed and compared before and after daily loading. Results: The achieved comparative errors between the FE results and clinical images were on average below 20% and 25% for pre-op and post-op models, respectively, which confirms the applicability of this predictive algorithm for rough pre-planning estimations. The results showed that the disc height loss and fluid loss were increased for the adjacent discs in post-op models after 16h of cyclic loading. In addition, significant differences in disc height loss and fluid loss were observed between the patients who were in the non-ASD and ASD groups. Similarly, the increased stress and fiber strain in the annulus fibrosus (AF) was higher in the adjacent level of post-op models. However, the calculated stress and fiber strain values were significantly higher for patients with ASD. Discussion: Evaluating the biomechanical response of pre-op and post-op modeling in the non-ASD and ASD groups showed that the inherent geometric differences among patients cause significant variations in the estimated mechanical response. In conclusion, the results of the current study highlighted the effect of geometrical parameters (which may refer to the anatomical conditions or the induced modifications regarding surgical techniques) on time-dependent responses of lumbar spine biomechanics.

Lateral Mass Screws Versus Pedicle Screws at C7: Reoperation Rates for Operative Adjacent Segment Disease and Nonunion in Posterior Cervical Fusion.

A retrospective cohort study. To determine if there is a difference in reoperation rates for symptomatic adjacent segment disease (operative ASD) and symptomatic nonunions (operative nonunions) in posterior cervical fusions (PCFs) stopping at C7 using either lateral mass screws (LMS) or cervical pedicle screws (CPS) at C7. Stopping PCFs at C7 has been controversial because of the risks of adjacent segment disease or nonunions. The two commonly used fixation techniques at the C7 level are LMS and CPS. A retrospective analysis from the Kaiser Permanente Spine Registry identified a cohort of patients with cervical degenerative disk disease who underwent primary PCFs stopping at C7 with either LMS or CPS at C7. Demographic and operative data were extracted from the registry, and operative ASD and operative nonunions were adjudicated through chart review. Patients were followed until validated operative ASD or nonunion, membership termination, death, or end of study (March 31, 2022). Descriptive statistics and multivariable Cox proportional hazards models were calculated for operative ASDs and operative nonunions. We found 481 patients with PCFs stopping at C7 with either LMS (n=347) or CPS (n=134) at C7 with an average follow-up time of 5.6 (±3.8) years, time to operative ASD of 3.0 (±2.8) years, and to operative nonunion of 1.2 (±0.7) years. There were 11 operative ASDs (LMS=8, CPS=3) and eight operative nonunions (LMS=4, CPS=4). There was no statistical difference between patients stopping at C7 with LMS versus CPS for operative ASDs (HR: 0.68, 95% CI=0.17-2.77, P =0.60) or operative nonunions (HR: 2.09, 95% CI=0.45-8.58, P =0.37). A large cohort of patients with PCFs stopping at C7 with an average follow-up of > 5 years found no statistical difference in reoperation rates for symptomatic ASD (operative ASD) or operative nonunion using either LMS or CPS at C7.

Safety and clinical efficacy of endoscopic procedures for the treatment of adjacent segmental disease after lumbar fusion: A systematic review and meta-analysis.

Adjacent segment disease (ASD) is a common complication after lumbar fusion and is still traditionally treated by open surgery. In recent years, with the development of minimally invasive techniques, percutaneous endoscopic surgery(PES) has been used for the treatment of ASD after lumbar fusion due to its unique benefits. Nevertheless, it remains unclear about its significant clinical efficacy and advantages over conventional open surgery. To evaluate the clinical efficacy and safety of PES in the treatment of ASD after lumbar fusion. A systematic review and meta-analysis studies about the role of PES in managing ASD after lumbar fusion. A systematic search review was conducted in PubMed, EMBASE, Cochrane Library, Web of Science, CNKI, VIP, WanFang, and SinoMed databases from the start of their construction to 15 November 2021. Eligible studies included references to clinical trials of PES for ASD after open lumbar fusion. Observations included pain relief, recovery of postoperative function, overall excellent rates, and indicators of the advantages of minimally invasive surgery compared to conventional surgery. Postoperative complications and recurrence rates were also recorded. A total of 24 studies, including 20 single-arm studies and 4 clinical control studies, all involving 928 patients were included. A total of 694 patients were included in the single-arm analysis. The results of the single-arm meta-analysis showed that PES could significantly reduce low back and leg pain and improve the functional status of the lumbar spine in patients with ASD after open lumbar fusion compared to preoperatively, and had good clinical efficacy after surgery. A total of 234 patients were included in the four clinically controlled studies, and the results of the meta-analysis showed that PES could clearly reduce pain and improve lumbar function, with no significant difference in efficacy between PES and open surgery. However, PES has a lower surgical incision, less intraoperative bleeding, and shorter operative time and length of hospital stay compared to open surgery. Moreover, it has a lower rate of postoperative recurrence as well as complications and a longer duration of efficacy. On the basis of the available clinical literature and the results of this study, PES could achieve satisfactory clinical effects in ASD treatment after lumbar fusion. Compared with conventional open surgery, PES can not only obtain similar clinical results, but also had the advantages of less trauma and faster recovery. Nevertheless, a randomized controlled study is still needed to validate the findings of this study. Systematic review registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42022298387.

Complications in cervical total disc arthroplasty

Cervical total disc arthroplasty (CTDA) is an alternative to cervical fusion when addressing single level cervical disc disease and attempts to restore normal disc height and preserve motion, theoretically decreasing rates of adjacent segment disease (ASD) and symptomatic pseudoarthrosis. Although safe and effective, CTDA has a unique complication profile particularly in regard to long-term complications. Approach related complications are similar to anterior cervical discectomy and fusion (ACDF) and include injury to surrounding vascular, digestive, and neurologic structures. To achieve anatomic positioning, CTDA requires vertebral endplate cartilage removal and osseous preparation which can lead to endplate fracture, salvage fusion, or component malpositioning. Long term complications include heterotopic ossification (HO), implant subsidence, ASD requiring surgical intervention, and implant migration or translation. Although HO reduces motion at the prosthesis site, it does not appear to worsen clinical outcomes in most cases. Evidence is still conflicting regarding ASD when comparing ACDF to CTDA, however, the most recent evidence suggests a lower rate of development with CTDA.

Update on design and biomechanics of cervical disc arthroplasty

Anterior cervical discectomy and fusion (ACDF) has been considered the mainstay of care for cervical spondylosis despite its association with decreased spinal mobility, altered kinematics, and risk of adjacent segment disease. Cervical disc arthroplasty (CDA) has recently emerged as a potential alternative that allows for preservation of motion and restoration of physiologic load distribution at both the index and adjacent levels. The growing interest and strong clinical evidence supporting the use of CDA has led to several changes in implant design. This review aims to discuss the implementation of CDA as an alternative to ACDF as well as provide an update on advancements in implant design and their influence of spinal biomechanics.

Biomechanical comparative analysis of conventional pedicle screws and cortical bone trajectory fixation in the lumbar spine: An in vitro and finite element study.

Numerous screw fixation systems have evolved in clinical practice as a result of advances in screw insertion technology. Currently, pedicle screw (PS) fixation technology is recognized as the gold standard of posterior lumbar fusion, but it can also have some negative complications, such as screw loosening, pullout, and breakage. To address these concerns, cortical bone trajectory (CBT) has been proposed and gradually developed. However, it is still unclear whether cortical bone trajectory can achieve similar mechanical stability to pedicle screw and whether the combination of pedicle screw + cortical bone trajectory fixation can provide a suitable mechanical environment in the intervertebral space. The present study aimed to investigate the biomechanical responses of the lumbar spine with pedicle screw and cortical bone trajectory fixation. Accordingly, finite element analysis (FEA) and in vitro specimen biomechanical experiment (IVE) were performed to analyze the stiffness, range of motion (ROM), and stress distribution of the lumbar spine with various combinations of pedicle screw and cortical bone trajectory screws under single-segment and dual-segment fixation. The results show that dual-segment fixation and hybrid screw placement can provide greater stiffness, which is beneficial for maintaining the biomechanical stability of the spine. Meanwhile, each segment's range of motion is reduced after fusion, and the loss of adjacent segments' range of motion is more obvious with longer fusion segments, thereby leading to adjacent-segment disease (ASD). Long-segment internal fixation can equalize total spinal stresses. Additionally, cortical bone trajectory screws perform better in terms of the rotation resistance of fusion segments, while pedicle screw screws perform better in terms of flexion-extension resistance, as well as lateral bending. Moreover, the maximum screw stress of L4 cortical bone trajectory/L5 pedicle screw is the highest, followed by L45 cortical bone trajectory. This biomechanical analysis can accordingly provide inspiration for the choice of intervertebral fusion strategy.

Will the adjustment of insertional pedicle screw positions affect the risk of adjacent segment diseases biomechanically? An in-silico study.

The fixation-induced biomechanical deterioration will increase the risk of adjacent segment diseases (ASD) after lumbar interbody fusion with Bilateral pedicle screw (BPS) fixation. The accurate adjustment of insertional pedicle screw positions is possible, and published studies have reported its mechanical effects. However, no studies clarified that adjusting insertional screw positions would affect the postoperative biomechanical environment and the risk of ASD. The objective of this study was to identify this issue and provide theoretical references for the optimization of insertional pedicle screw position selections. The oblique lumbar interbody fusion fixed by BPS with different insertional positions has been simulated in the L4-L5 segment of our previously constructed and validated lumbosacral model. Biomechanical indicators related to ASD have been computed and recorded under flexion, extension, bending, and axial rotation loading conditions. The change of screw insertional positions has more apparent biomechanical effects on the cranial than the caudal segment. Positive collections can be observed between the reduction of the fixation length and the alleviation of motility compensation and stress concentration on facet cartilages. By contrast, no pronounced tendency of stress distribution on the intervertebral discs can be observed with the change of screw positions. Reducing the fixation stiffness by adjusting the insertional screw positions could alleviate the biomechanical deterioration and be an effective method to reduce the risk of ASD caused by BPS.