Risk Of Adjacent Segment Degeneration Research Articles

Comparative analysis of risk factors associated with degeneration of adjacent segments: zero-profile anchored spacer vs. anterior cervical plate and cage construct.

Anterior cervical discectomy and fusion (ACDF) is an established treatment for cervical degenerative disc disease, but cervical spine surgery may affect sagittal alignment parameters and induce adjacent segment degeneration (ASD). This study aimed to determine the risk factors for developing ASD following anterior cervical plate and cage (ACPC) compared with the use of zero-profile anchored spacer (ROI-C). A retrospective contrastive study included 105 patients who underwent ACPC or ROI-C between January 2014 and October 2019 at our treatment centre. There were 50 cases in the ROI-C group and 55 patients in the ACPC group. Clinical and radiological results and the incidence of ASD were assessed after surgery. All patients were further divided into the ASD and non-ASD groups for subgroup analysis. At each follow-up time, there was no statistically significant in radiographic parameters between the two groups. The overall ASD rate was higher in the ACPC group than in the ROI-C group (65.5% vs. 44.0%, p = 0.027). The low preoperative Cobb angle, low preoperative segment angle (SA), and loss of Cobb (ΔCobb) were significantly correlated with ASD. However, clinical outcomes were not associated with ASD at any postoperative follow-up visit. Equally good therapeutic effects were achieved with both the ROI-C and ACPC. The occurrence of ASD was considerably higher in the ACPC group than in the ROI-C group. The preoperative Cobb angle, preoperative SA, and ΔCobb were the most associated with an increase in the risk of ASD.

Laminoplasty Versus Laminectomy and Posterior Fusion for Cervical Myelopathy: A Meta-analysis of Radiographic and Clinical Outcomes.

Meta-analysis. This meta-analysis investigates the outcomes of laminoplasty (LP) and laminectomy with fusion (LF) to guide effective patient selection for these two procedures. While LF traditionally offers the ability for excellent posterior decompression, it may alter cervical spine biomechanics and increase the risk of adjacent segment degeneration. LP aims to preserve the natural kinematics of the spine but has not been universally accepted, and may be associated with inadequate decompression, neck pain, and recurrent stenosis. PubMed, Cochrane, and Google Scholar (Pages 1-20) were searched up until March 2024. The outcomes studied were surgery-related outcomes (operating room (OR) time, estimated blood loss (EBL), and length of stay (LOS)), adverse events (overall complications, C5 palsy, and reoperations), radiographic outcomes (cervical lordosis (CL), cervical sagittal vertical axis (cSVA), and T1 slope angle (T1SA)), and patient-reported outcome measures (PROMs) (Neck Disability Index (NDI), Visual Analog Scale (VAS) for neck pain, and Japanese Orthopaedic Association (JOA)). Twenty-two studies were included in this meta-analysis, of which 19 were retrospective studies, two were prospective non-randomized studies, and one was a randomized controlled trial. A total of 2,128 patients were included, with 1,025 undergoing LP and 1,103 undergoing LF. LP patients experienced significantly shorter OR time (P=0.009), less EBL (P=0.02), a lower rate of overall complications (P<0.00001) and C5 palsy (P=0.003), a lower T1SA (P=0.02), and a lower NDI (P=0.0004). No significant difference was observed in the remaining outcomes. This meta-analysis demonstrates that for cervical myelopathy, LP has the benefits of shorter OR time, less EBL, and reduced incidence of C5 palsy as well as overall complication rate. Given these findings, LP remains an important surgical option with a favorable complication profile in patients with cervical myelopathy, although careful patient selection is still paramount in choosing the right procedure for individual patients.

Intraoperative capsule protection can reduce the potential risk of adjacent segment degeneration acceleration biomechanically: an in silico study

BackgroundThe capsule of the zygapophyseal joint plays an important role in motion segmental stability maintenance. Iatrogenic capsule injury is a common phenomenon in posterior approach lumbar interbody fusion operations, but whether this procedure will cause a higher risk of adjacent segment degeneration acceleration biomechanically has yet to be identified.MethodsPosterior lumbar interbody fusion (PLIF) with different grades of iatrogenic capsule injury was simulated in our calibrated and validated numerical model. By adjusting the cross-sectional area of the capsule, different grades of capsule injury were simulated. The stress distribution on the cranial motion segment was computed under different loading conditions to judge the potential risk of adjacent segment degeneration acceleration.ResultsCompared to the PLIF model with an intact capsule, a stepwise increase in the stress value on the cranial motion segment can be observed with a step decrease in capsule cross-sectional areas. Moreover, compared to the difference between models with intact and slightly injured capsules, the difference in stress values was more evident between models with slight and severe iatrogenic capsule injury.ConclusionIntraoperative capsule protection can reduce the potential risk of adjacent segment degeneration acceleration biomechanically, and iatrogenic capsule damage on the cranial motion segment should be reduced to optimize patients’ long-term prognosis.

Fusion with and without lever reduction in degenerative lumbar spondylolisthesis: a retrospective study.

The reduction of slipped vertebra is often performed during surgery for degenerative lumbar spondylolisthesis (DLS). This approach, while potentially improving clinical and radiological outcomes, also carries a risk of increased complications due to the reduction process. To address this, we introduced an innovative lever reduction technique for DLS treatment. This study aims to investigate the clinical efficacy, radiological outcomes, and complications of fusion with or without lever reduction. We conducted a retrospective review of prospectively collected data from a registry of patients who underwent lumbar fusion surgery for DLS, with a follow-up of at least 24months. Self-reported measures included visual analog scale (VAS) for back or leg pain, Oswestry Disability Index (ODI), and the achievement of minimal clinically important difference (MCID). Radiological assessments encompassed spondylolisthesis percentage (SP), focal lordosis (FL), and lumbar lordosis (LL). Complications were categorized using the modified Clavien-Dindo classification (MCDC) scheme. Patients were assigned to the reduction group (RG) and non-reduction group (NRG) based on the application of the lever reduction technique. Clinical and radiological outcomes at baseline, immediately after surgery, and at the last follow-up were compared. A total of 281 patients were analyzed (123 NRG, 158 RG). Baseline patient demographics, comorbidities, and surgical characteristics were similarly distributed between groups except for operating time (NRG 129.25min, RG 138.04min, P = .009). Both groups exhibited significant clinical improvement after surgery (all, P = .000), with no substantial difference between groups (VAS, ODI, or the ability to reach MCID). Patients in RG showed statistically lower SP and higher FL during follow-up (all, P = .000). LL was comparable at different time points within each group or at the same time point between the two groups (all, P > .050). The overall complication rate (NRG 38.2%, RG 27.2%, P = .050) or specific complication rates per MCDC were similar between groups (all, P > .050). Patients in RG were predisposed to a lower risk of adjacent segment degeneration (ASDeg) (NRG 9.8%, RG 6.3%, P = .035). There were no significant differences in postoperative measures such as VAS scores for back and leg pain, ODI, the ability to reach MCID, overall complication rate, or specific complication rates per MCDC between surgical approaches. However, fusion with lever reduction demonstrated a notable advantage in restoring segmental spinal sagittal alignment and reducing the occurrence of ASDeg compared to in situ fusion.

Mid-term and Long-term Outcomes After Total Cervical Disk Arthroplasty Compared With Anterior Cervical Discectomy and Fusion: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

A meta-analysis of randomized controlled trials (RCTs). The aim of this study was to compare mid-term to long-term outcomes of cervical disk arthroplasty (CDA) with those of anterior cervical discectomy and fusion (ACDF) for the treatment of symptomatic cervical degenerative disk disease. After ACDF to treat symptomatic cervical degenerative disk disease, the loss of motion at the index level due to fusion may accelerate adjacent-level disk degeneration. CDA was developed to preserve motion and reduce the risk of adjacent segment degeneration. Early-term to mid-term clinical outcomes from RCTs suggest noninferiority of CDA compared with ACDF, but it remains unclear whether CDA yields better mid-term to long-term outcomes than ACDF. Two independent reviewers searched PubMed, Embase, and the Cochrane Library for RCTs with at least 60 months of follow-up. The risk ratio or standardized mean difference (and 95% CIs) were calculated for dichotomous or continuous variables, respectively. Eighteen reports of 14 RCTs published in 2014-2023 were included. The pooled analysis demonstrated that the CDA group had a significantly greater improvement in neurological success and Neck Disability Index than the ACDF group. The ACDF group exhibited a significantly better improvement in the Short Form-36 Health Survey Physical Component Summary than the CDA group. Radiographic adjacent segment degeneration was significantly lower in the CDA group at 60- and 84-month follow-ups; at 120-month follow-up, there was no significant difference between the 2 groups. Although the overall rate of secondary surgical procedures was significantly lower in the CDA group, we did not observe any significant difference at 60-month follow-up between the CDA and ACDF group and appreciated statistically significant lower rates of radiographic adjacent segment degeneration, and symptomatic adjacent-level disease requiring surgery at 84-month and 108- to 120-month follow-up. The rate of adverse events and the neck and arm pain scores in the CDA group were not significantly different from those of the ACDF group. In this meta-analysis of 14 RCTs with 5- to 10-year follow-up data, CDA resulted in significantly better neurological success and Neck Disability Index scores and lower rates of radiographic adjacent segment degeneration, secondary surgical procedures, and symptomatic adjacent-level disease requiring surgery than ACDF. ACDF resulted in improved Short Form-36 Health Survey Physical Component Summary scores. However, the CDA and ACDF groups did not exhibit significant differences in overall changes in neck and arm pain scores or rates of adverse events.

Biomechanical Evaluation of Rigid Interspinous Process Fixation Combined With Lumbar Interbody Fusion Using Hybrid Testing Protocol.

Rigid interspinous process fixation (RIPF) has been recently discussed as an alternative to pedicle screw fixation (PSF) for reducing trauma in lumbar interbody fusion (LIF) surgery. This study aimed to investigate biomechanics of the lumbar spine with RIPF, and also to compare biomechanical differences between two postoperative stages (before and after bony fusion). Based on an intact finite-element model of lumbosacral spine, the models of single-level LIF with RIPF or conventional PSF were developed and were computed for biomechanical responses to the moments of four physiological motions using hybrid testing protocol. It was found that compared with PSF, range of motion (ROM), intradiscal pressure (IDP), and facet joint forces (FJF) at adjacent segments of the surgical level for RIPF were decreased by up to 8.4%, 2.3%, and 16.8%, respectively, but ROM and endplate stress at the surgical segment were increased by up to 285.3% and 174.3%, respectively. The results of comparison between lumbar spine with RIPF before and after bony fusion showed that ROM and endplate stress at the surgical segment were decreased by up to 62.6% and 40.4%, respectively, when achieved to bony fusion. These findings suggest that lumbar spine with RIPF as compared to PSF has potential to decrease the risk of adjacent segment degeneration but might have lower stability of surgical segment and an increased risk of cage subsidence; When achieved bony fusion, it might be helpful for the lumbar spine with RIPF in increasing stability of surgical segment and reducing failure of bone contact with cage.

Dynamic Rod Constructs as the Preventive Strategy against Adjacent Segment Disease in Degenerative Lumbar Spinal Disorders: A Retrospective Comparative Cohort Study.

Adjacent segment degeneration (ASDe) and adjacent segment disease (ASDi) are potential long-term complications after lumbar fusion with rigid instrumentation. Dynamic fixation techniques (Topping-off) adjacent to the fused segments have been developed to curtail the risk of ASDe and ASDi. The current study sought to investigate whether the addition of dynamic rod constructs (DRC) in patients with preoperative degeneration in the adjacent disc was effective in reducing the risk of ASDi. A retrospective analysis was performed on clinical data of 207 patients with degenerative lumbar disorders (DLD) from January 2012 to January 2019, who underwent posterior transpedicular lumbar fusion (without Topping-off, NoT/O), and posterior dynamic instrumentation with DRC. Clinical and radiological outcomes were evaluated using Oswestry Disability Index (ODI), Visual Analogue Scale (VAS), and lumbar radiographs one, three, and 12 months postoperatively and annually. ASDe was defined as disc height collapse > 20% and disc wedging > 5. Patients with confirmed ASDe and aggravation of ODI > 20 or VAS score > 5 at final follow-up were diagnosed as ASDi. The Kaplan-Meier hazard method was used to estimate the cumulative probability of ASDi within 63 months of surgery. Over three years of follow-up, 65 patients in the NoT/O (59.6%) and 52 cases (53.1%) in the DRC groups met the diagnostic criteria for ASDe. Furthermore, 27 (24.8%) patients in the NoT/O group showed ASDi during the follow-up, compared to 14 (14.3%) cases in the DRC group (P=0.059). Revision surgery was performed on 19 individuals in the NoT/O and 8 cases in the DRC groups (P=0.048). The Cox regression model identified a significantly decreased risk of ASDi if DRC was used (Hazard ratio: 0.29; 95% CI: 0.13-0.6). Dynamic fixation adjacent to the fused segment is an effective strategy for preventing ASDi in carefully selected individuals with preoperative degenerative changes at the adjacent level.

Restoration and maintenance of segment lordosis in oblique lumbar interbody fusion

PurposeRestoration of the segment lordosis angle (SLA) can effectively reduce the risk of adjacent segment degeneration. This study aimed to perform a comprehensive multifactor analysis of the risk factors affecting restoration and maintenance of the SLA in oblique lumbar interbody fusion (OLIF).MethodsSeventy-three patients (93 segments) who underwent OLIF with posterior pedicle screw fixation due to lumbar degenerative disease between January 2015 and December 2019 were included. Radiographic parameters including the middle disc height (MDH), segment lordosis angle (SLA), cage center point ratio (CPR), cage subsidence, and L1 CT Hounsfield Unit (HU) were measured.ResultsThe postoperative SLA increased from 3.5° to 8.7°, and decreased to 6.7° at the last follow-up. Multivariate analysis showed that preoperative SLA, CPR and cage subsidence were significantly correlated with SLA restoration. The significant correlations were between restoration of SLA with pre-operative SLA (r=-0.575, adjusted R2 = 0.323, P < 0.01) and between SLA restoration and CPR (r = 0.526, adjusted R2 = 0.268, P < 0.01). Cage subsidence was found in 12.9% (12/93) of segments and was the main factor affecting SLA loss (4.2 ± 1.0° versus 1.7 ± 2.1°, P < 0.01). Logistic regression analysis showed that CPR < 50%, L1 CT HU < 110 and cage height > preoperative MDH were risk factors for cage subsidence. Cages placed anteriorly (CPR ≥ 50%) showed a large SLA increase and lower incidence of cage subsidence than those placed posteriorly (5.9 ± 3.9° versus 4.2 ± 3.2°, P < 0.05; 1.8% versus 28.9%, P < 0.05, respectively).ConclusionSLA restoration is dependent on preoperative SLA, cage subsidence and cage position in OLIF. Cage position is the key determinant of SLA restoration and placement of the cage at the anterior position (CPR ≥ 50%) can achieve better restoration of the SLA and reduce the incidence of cage subsidence.

Biomechanical Evaluation of Transforaminal Lumbar Interbody Fusion with Coflex-F and Pedicle Screw Fixation: Finite Element Analysis of Static and Vibration Conditions.

ObjectiveTo investigate the biomechanics of transforaminal lumbar interbody fusion (TLIF) with interspinous process device (IPD) or pedicle screw fixation under both static and vibration conditions by the finite element (FE) method.MethodA validated FE model of the L1‐5 lumbar spine was used in this study. This FE model derived from computed tomography images of a healthy female adult volunteer of appropriate age. Then the model was modified to simulate L3‐4 TLIF. Four conditions were compared: (i) intact; (ii) TLIF combined with bilateral pedicle screw fixation (BPSF); (iii) TLIF combined with U‐shaped IPD Coflex‐F (CF); and (iv) TLIF combined with unilateral pedicle screw fixation (UPSF). The intact and surgical FE models were analyzed under static and vibration loading conditions respectively. For static loading conditions, four motion modes (flexion, extension, lateral bending, and axial rotation) were simulated. For vibration loading conditions, the dynamic responses of lumbar spine under sinusoidal vertical load were simulated.ResultUnder static loading conditions, compared with intact case, BPSF decreased range of motion (ROM) by 92%, 95%, 89% and 92% in flexion, extension, lateral bending and axial rotation, respectively. While CF decreased ROM by 87%, 90%, 69% and 80%, and UPSF decreased ROM by 84%, 89%, 66% and 82%, respectively. Compared with CF, UPSF increased the endplate stress by 5%–8% in flexion, 7%–10% in extension, 2%–4% in lateral bending, and decreased the endplate stress by 16%–19% in axial rotation. Compared with CF, UPSF increased the cage stress by 9% in flexion, 10% in extension, and decreased the cage stress by 3% in lateral bending, and 13% in axial rotation. BPSF decreased the stress responses of endplates and cage compared with CF and UPSF. Compared BPSF, CF decreased the facet joint force (FJF) by 6%–13%, and UPSF decreased the FJF by 4%–12%. During vibration loading conditions, compared with BPSF, CF reduced maximum values of the FJF by 16%–32%, and vibration amplitudes by 22%–35%, while UPSF reduced maximum values by 20%–40%, and vibration amplitudes by 31%–45%.ConclusionCompared with other surgical models, BPSF increased the stability of lumbar spine, and also showed advantages in cage stress and endplate stress. CF showed advantages in IDP and FJF especially during vertical vibration, which may lead to lower risk of adjacent segment degeneration. CF may be an effective alternative to pedicle screw fixation in TLIF procedures.

Impact of Patient-specific Factors and Spinopelvic Alignment on the Development of Adjacent Segment Degeneration After Short-segment Lumbar Fusion.

Prospective cross-sectional cohort study. The main purpose of this study was to evaluate the association between demographical, surgery-related and morphologic parameters, and the development or progress of adjacent segment degeneration (ASD) after short-segment lumbar fusions. ASD is a major long-term complication after lumbar fusions. Possible risk factors are related to the patients' demographics, spinopelvic anatomy, or preoperative lumbar intervertebral disk conditions, but the role of these parameters is still not clear. A prospective cross-sectional study of 100 patients who underwent 1- or 2-level open lumbar transforaminal interbody fusions due to a lumbar degenerative pathology was conducted. Demographical, radiologic findings, and magnetic resonance imaging features were analyzed to identify factors associated with ASD in 5-year follow-up. ASD patients showed higher level of pain ( P =0.004) and disability ( P =0.020) at follow-up. In univariate analysis, older age ( P =0.007), upper-level lumbar fusion ( P =0.007), lower L4-S1 lordosis ( P =0.039), pelvic incidence-lumbar lordosis mismatch ( P =0.021), Pfirrmann grade III or higher disk degeneration ( P =0.002), and the presence of disk bulge/protrusion ( P =0.007) were associated with ASD. In multivariate analysis, the presence of major degenerative sign (disk degeneration and/or disk bulge) was the significant predictor for developing ASD (odds ratio: 3.85, P =0.006). By examining the role of different patient- and procedure-specific factors, we found that preoperative major degenerative signs at the adjacent segment increase the risk of ASD causing significantly worse outcome after short-segment lumbar fusion. On the basis of our results, adjacent disk conditions should be considered carefully during surgical planning.

The effectiveness of short hybrid stabilization with sublaminar bands and transpedicular screws in the treatment of thoracolumbar spine fractures.

Long constructs have always been widely recommended for the treatment of thoracolumbar fractures, due to their biomechanical stability and minimal postoperative loss of correction. However, short constructs have significant advantages, since they enable for better postoperative lumbar mobility and reduce the risk of adjacent segment degeneration. The purpose of this study is to evaluate the safety and efficacy of hybrid screw/sublaminar bands short constructs, used for the treatment of thoracolumbar fractures. From June 2015 until November 2017, 20 consecutive patients (14 male, 6 female) with an average age of 52.9 years, exhibiting at least one traumatic fracture in the thoracolumbar region, were treated with hybrid screw/sublaminar bands short constructs. The data for analysis included: duration of the intervention, intraoperative blood loss, complications, and clinical and radiographic postoperative results, compared with the standard for thoracolumbar fixation. The use of this type of construct allowed for simple reduction, stabilization of the fractures, and restoration of the physiological spine curvatures. During the postoperative period none of the patients had neurological worsening. 18 out of 20 patients were followed up for two years. One patient sustained implant failure six months after surgery and underwent a surgical implant revision with traditional long fixation. After two years, stability and fusion were obtained in all patients, along with correct spine alignment. Hybrid screw/sublaminar bands short constructs seem to be effective in the treatment of thoracolumbar fractures, providing the same clinical results of the state-of-the-art pedicular screw/rod long constructs, but in addition they allow for better postoperative lumbar mobility and subsequently reduce the risk of adjacent segments degeneration. The results of this clinical case series might support the initiation of prospective randomized trials with more patients, a longer follow-up period, and control groups.

What's New in Spine Surgery.

What's New in Spine Surgery.

Impact of heterotopic ossification following lumbar total disk replacement: a systematic review

Background contextLumbar total disc replacement (TDR) is an alternative to lumbar fusion in the treatment of lower back pain and reduces the risk of adjacent segment degeneration. Heterotopic ossification (HO) has been identified as a common complication following lumbar TDR.PurposeThis systematic review aims to determine the prevalence, risk factors and clinical and radiological impact of HO following lumbar TDR.Study DesignSystematic Review.MethodsMEDLINE, Scopus, PubMed and Cochrane Central were searched for articles that referred to lumbar TDR and HO. The hits were assessed against inclusion and exclusion criteria. Data from each included study was extracted and analysed with respect to the study aims.ResultsTwenty-six studies were included in this review and the pooled prevalence of HO was estimated to be between 13.2% (participants) and 15.3% (vertebral levels). TDR clinical outcomes were not found to be reduced by HO and there was insufficient data to identify a given impact upon radiological outcomes. Age and follow up time were identified as potential risk factors for HO.ConclusionsThis review was hampered by inconsistencies in the reporting of HO across the studies. We therefore recommend that a set of guidelines should be produced to aid future researchers and reduce the risk of bias.

The biomechanical effects of S-type dynamic cage using Ti and PEEK for ACDF surgery on cervical spine varying loads

Anterior cervical discectomy with fusion (ACDF) is the common method to treat the cervical disc degeneration. The most serious problems in the fusion cages are adjacent disc degeneration, loss of lordosis, pain, subsidence, and migration of the cage. The objective of our work is to develop the three-dimensional finite element (FE) model from C3-C6 and virtually implant a designed S-type dynamic cage at C4-C5 segment of the model. The dynamic cage design will provide mobility in the early stage after ACDF surgery. Titanium (Ti) and PEEK (polyether ether ketone) were used as the material property for the cages. We applied the physiological motions at different loads from 0.5, 1, 1.5, 2.0 Nm to evaluate the dynamic cage design and the biomechanical performances of the designed S-type dynamic cage. It was observed that in all the loading condition the range of motion in the adjacent level was maintained and the maximum stress at the adjacent disc was reduced. The clinical significance of the S-type dynamic cage is better stress profile at the fusion level and adjacent segments which translates into higher rate of fusion, lower risk of cage subsidence, lower risk of adjacent segment degeneration, and good mechanical stability.

Dynamic Fixation Techniques for the Prevention of Adjacent Segment Disease: A Retrospective Controlled Study.

Study DesignRetrospective, controlled study.PurposeDynamic fixation (topping-off technique) adjacent to a transforaminal lumbar interbody fusion (TLIF) level was developed to reduce the risk of adjacent segment disease (ASDi). This study was designed to compare the clinical and radiological outcomes between patients who underwent circumferential lumbar fusion (CLF) without the topping-off technique, CLF with dynamic rod constructs (DRC), and CLF with interspinous device (ISD).Overview of LiteratureLumbar fusion can result in the re-distribution of stress, increased mobility, and increased intradiscal pressure at adjacent levels, ultimately leading to adjacent segment degeneration (ASDe) and ASDi. Dynamic fixation techniques (topping-off techniques) adjacent to vertebral fusion have been developed to reduce the risk of ASDe and ASDi because they provide a transitional zone between a caudal rigid fused segment and cephalad-mobile unfused levels.MethodsA single-center, retrospective, controlled study was designed, including all patients who underwent CLF due to degenerative lumbar spinal disease in Hospital Clinic of Barcelona between 2012 and 2018. Three groups of patients were evaluated as per the type of topping-off technique used: CLF alone group, DRC group, and ISD group. Clinical and radiological outcomes were evaluated.ResultsA total of 117 patients were enrolled in the study. Sixty patients (51.3%) underwent CLF without dynamic stabilization, 24 (20.5%) were treated with DRC as topping-off technique, and 33 (28.5%) were treated with an ISD. A total of 12 patients (20.0%) in the CLF alone group showed ASDi at the final follow-up, compared to 1 (4.2%) in the DRC group (p=0.097) and 2 (6.1%) in the ISD group (p=0.127). The Cox regression model identified a significantly decreased risk of ASDi when a topping-off technique (DRC or ISD) was used (hazard ratio, 0.154; 95% confidence interval, 0.31–0.77).ConclusionsDynamic fixation adjacent to CLF was a safe and efficient procedure associated with improved clinical outcomes in patients with lumbar spine degenerative disease.

Proximal Fusion Level Above First Coronal Reverse Vertebrae: An Essential Factor Decreasing the Risk of Adjacent Segment Degeneration in Degenerative Lumbar Scoliosis.

Retrospective radiological analysis. To explore whether proximal fusion level above first coronal reverse vertebrae (FCRV) could decrease risk of adjacent segment degeneration (ASD) in degenerative lumbar scoliosis (DLS). One hundred and 16 DLS patients were divided into 2 groups according to occurrence of ASD: study group (ASD positive group) and control group (ASD negative group). FCRV was defined as the first vertebrae that presents opposite orientation of asymmetric Hounsfield unit (HU) ratio from the other vertebrae within major curve. Incidence of ASD was evaluated in subgroups according to location between FCRV and upper instrumented vertebrae (UIV). The fusion level was shorter in study group than that in control group. There were 12 patients presented FCRV 2-level proximal than SV, 32 patients presented FCRV 1-level proximal than SV, 35 patients presented the same vertebra of FCRV with SV, 23 patients presented FCRV 1-level distal than SV, 14 patients presented FCRV 2-level distal than SV. When UIV located above FCRV, no patient presented ASD, while 15.4% patients presented ASD when UIV located on FCRV. In study group, proximal scoliosis progression was detected in 1 patient (3.9%) when UIV located on FCRV, and 17 patients (29.8%) when UIV located below FCRV. Proximal fusion level above FCRV could decrease the risk of ASD in DLS, especially for the proximal scoliosis progression. FCRV represent the transitional point of the mechanical load on coronal plane, and may be within a more stable condition than stable vertebrae measured from radiographs.

48. Fusion and decompression vs decompression only for lumbar facet cysts

BACKGROUND CONTEXT Lumbar facet cysts are associated with radiculopathy, neurogenic claudication and higher risk of dural tears. Consensus on the best method to address these lesions is lacking (fusion vs decompression only). Outcomes after surgery are of increasing interest to spine surgeons, particularly when seeking to offer the most conservative, yet effective, option. Our objective is to describe complications, outcomes and recurrence rates following surgical intervention of facet cysts. PURPOSE To evaluate surgical outcomes of facet cyst treatment. STUDY DESIGN/SETTING Retrospective cohort PATIENT SAMPLE Patients with lumbar facet cyst treated at a single site by multiple surgeons between 2009 and 2017. OUTCOME MEASURES Revision surgeries, estimated blood loss, adjacent segment disease, length of hospital stay. METHODS A retrospective analysis of patients diagnosed with lumbar facet cysts who underwent treatment for their condition at a single academic tertiary care facility between 2008 and 2018. Patients underwent surgical treatment (fusion + decompression [DF] or decompression only [DO]). All patients were evaluated for surgical approach, facet cyst level, postop complication, cyst recurrence, EBL and length of hospital stay. Adjacent segment disease rates were also assessed. RESULTS A total of 140 patients were assessed. Mean age was 63.4 (43-93) including 80F and 60M. A total of 114 underwent DO and 26 patients underwent DF. The majority of the cysts 56% (n=78) were at L4-L5, followed by 24% (n=34) at L5-S1, 16% (n=22) at L3-L4 and 4% (n=6) at L2-L3. The recurrence rate in the DO group was 8% (9/114) as compared to 0 in the DF (p CONCLUSIONS Patients who undergo DF have an increased risk of adjacent segment degeneration but decreased rate of recurrence. The rate of cyst recurrence is higher among those treated by decompression alone; however, adjacent segment disease, blood loss, and length of hospital stay are lower. Four patients treated initially with DO underwent revision procedures with fusions after cyst recurrence. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

77. The incidence of subsequent lumbar spine surgery after lumbar disc arthroplasty: a minimum two-year follow-up

BACKGROUND CONTEXT Low back pain is one of the most common causes of disability in the United States. When conservative management fails, lumbar fusion in properly indicated patients has been considered the gold standard. However, lumbar disc arthroplasty is an alternative surgical option to spinal arthrodesis that may avoid the undesirable consequences of fusion including immobility and increased risk of adjacent segment degeneration. PURPOSE Surgical intervention rates following lumbar disc arthroplasty have been reported via the FDA investigational device exemption studies. However, these single institution studies and their findings may not be generalizable to the orthopedic community. We used the New York Statewide Planning and Research Cooperative System (SPARCS) database to identify the risk factors and incidence of subsequent lumbar spine surgery in patients undergoing primary lumbar disc arthroplasty. STUDY DESIGN/SETTING We analyzed the New York Statewide Planning and Research Cooperative System (SPARCS) inpatient database from 2005 to 2013 to retrospectively identify patients who underwent isolated lumbar disc arthroplasty. We used SAS version 9.4 to analyze de-identified data. Each patient had a unique patient identifier allowing for longitudinal follow-up. We followed patients for a minimum of two years. PATIENT SAMPLE We used the New York Statewide Planning and Research Cooperative System database to extract all index cases of lumbar disc arthroplasty (ICD9: 84.65) in New York State. A total of 1,372 patients underwent an inpatient lumbar disc arthroplasty procedure between January 2005 and September 2013. OUTCOME MEASURES The outcome of interest was subsequent lumbar re-operation. We further characterized re-operation by revision lumbar disc arthroplasty, anterior lumbar fusion, posterior lumbar fusion, lateral lumbar fusion, and laminectomy without fusion. METHODS International Classification of Diseases, Ninth Revision (ICD-9) codes were used to extract the index lumbar disc arthroplasty procedure (84.65) and to identify patient demographics and re-operation procedures. Patients were longitudinally followed until September 2015, corresponding to a minimum two-year follow-up, to determine the incidence of subsequent lumbar spine re-operation, which included revision lumbar disc arthroplasty, anterior lumbar fusion, posterior lumbar fusion, lateral lumbar fusion and laminectomy without fusion. Univariate and multivariate analyses were used to identify demographic risk factors for subsequent re-operation. RESULTS A total of 1,372 patients underwent an inpatient lumbar disc arthroplasty procedure between January 2005 and September 2013. Over the study duration, a decreasing number of inpatient lumbar disc arthroplasty procedures were performed in New York State (m=30 cases/year, p 40), sex, race, insurance, comorbidity score, tobacco use or lumbar diagnosis for the index lumbar disc arthroplasty procedure. CONCLUSIONS We identified a 17.6% incidence of subsequent lumbar spine surgery after inpatient lumbar disc arthroplasty, and an 8.8% re-operation rate at two years. Over the study duration, 14.2% underwent a subsequent lumbar fusion procedure. Diabetes mellitus was the only patient demographic factor to significantly influence the odds of lumbar spine re-operation. Inpatient lumbar disc arthroplasty procedures declined over the study duration in New York State. Further investigation is needed to evaluate if these findings correlate with the newest generation of lumbar disc arthroplasty designs. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Biomechanical evaluation of anterior and posterior lumbar surgical approaches on the adjacent segment: a finite element analysis

The purpose of this study was to use models of spine to compare range of motion and intradiscal pressure of adjacent segments performing anterior and/or posterior lumbar surgical approaches and predict potential risk of adjacent segment degeneration. A previously validated finite element model of the intact L1-S1 segments was used. Three different anterior and one posterior surgical fixation approaches for tuberculosis were performed in L3-L5. Three different anterior surgical models were constructed according to the anterior approaches involving debridement, bone graft with or without titanium mesh, and internal fixation with different number of screws and rods. The posterior surgical approach involved transforaminal lumbar interbody debridement, bone graft, and internal fixation. Range of motion and intradiscal pressure of segments adjacent to the fusion were assessed, and biomechanical influences were compared. Intradiscal pressure and range of motion of the adjacent L2/3 and L5/S1 increased during different physiological movements after anterior and/or posterior surgical approaches as compared to baseline values. Comparison between the biomechanical values assessed after different anterior surgical approaches yielded no significant difference. After anterior and posterior surgical approaches were performed on the same model, there were no significant differences in intradiscal pressure and range of motion of the adjacent L2/3 and L5/S1. Anterior and/or posterior lumbar surgical approaches increased range of motion and intradiscal pressure in L2/3 and L5/S1, suggesting each lumbar surgical approach assessed has the potential risk of adjacent segment degeneration. However, there were no significant differences between the biomechanical measurements across the different surgical approaches evaluated.

Influence of cement-augmented pedicle screw instrumentation in an osteoporotic lumbosacral spine over the adjacent segments: a 3D finite element study

PurposeTo compare the effect of conventional pedicle screw (CPS) and cement-augmented pedicle screw instrumentation (CAPSI) on adjacent segment degeneration (ASD).MethodsA normal male volunteer without a history of spinal disease was selected, lumbar CT data was collected, an intact L3-S1 three-dimensional finite element model was created by software including Mimics, Geomagic, and SolidWorks, and the fixation methods were performed accordingly. A common pedicle screw model and a cement-augmented pedicle screw model of L4–L5 with fusion and internal fixation were constructed. With ANSYS Workbench 17.0, a 500 N load was applied to the upper surface of L3 to simulate the weight of a human body, and a 7.5 N m moment was applied at the neutral point to simulate flexion, extension, left/right bending, left/right rotation of the spine. The peak von Mises stress of intervertebral disc and the range of motion (ROM) on the adjacent segments (L3–4 and L5–S1) were compared.ResultsThe validity of the intact model shows that the ROM of the model is similar to that of a cadaveric study. Compared with the intact model, CPS model and CAPSI model in all motion patterns increased the ROM of adjacent segments. The intervertebral disc stress and the ROM of adjacent segments were found to be higher in the CAPSI model than in the CPS model, especially in L3–4.ConclusionIn general, the biomechanical analysis of an osteoporotic lumbar spine showed that both CPS and CAPSI can increase the ROM and disc stresses of osteoporotic lumbar models, and compared with CPS, CAPSI is more likely to increase the potential risk of adjacent segment degeneration.