Adjacent segment degeneration and adjacent segment disease: the consequences of spinal fusion?

Predictive factors of surgical adjacent segment disease in the cervical spine: A nested case-control study

STUDY DESIGN

Nested case-control study.

OBJECTIVE

Radiological adjacent segment degeneration is reported in a significant proportion of patients operated on following ACDF. Only a part of them will experience clinical symptoms, ultimately requiring a second cervical spine surgery (SASD). Our retrospective observational study, with prospective data collection, aims at considering the potential influence of cervical sagittal balance on post-ACDF second surgery based on postoperative imaging follow-up. Four key potential predictive factors were evaluated between cases and controls.

METHODS

Between January 1st, 2014, to January 1st, 2020, 1078 patients were operated on for ACDF in the Spine Department of Lille University Hospital. We identified 19 cases and 76 matched controls. Cases were defined as follow: >18 y/o, operated on for a second ACDF related to a SASD. Controls patients did not undergo a second cervical surgery during the study period.

RESULTS

The prevalence of SASD was 1.76%. Neither the cervical sagittal axis (p = 0.12), nor the cervical lordosis (p = 0.40) were related to SASD. However, we reported a strong tendency for the numbers of levels operated on and the postoperative local kyphosis to be risk factors of SASD (respectively p = 0.056 and p = 0.06).

CONCLUSION

We did not report a clear impact of the cervical spine balance parameters such as cervical lordosis or cSVA on the risk of second cervical surgery at 2 years. Though, we highlighted the potential correlation between the initial number of cervical spine levels operated on and the occurrence of sASD and the presence of early local kyphosis.

Do all symptomatic adjacent segment diseases (ASD) require surgery? a prognostic classification and predictors of surgical treatment of lumbar ASD

INTRODUCTION

Symptomatic Adjacent segment disease presents in myriad ways with varying clinic-radiological presentation but the optimal management and the factors that predict need for revision surgery are unclear.

METHODOLOGY

Consecutive patients (n = 132) who experienced significant back or leg pain after an asymptomatic period (minimum 1 year) following a lumbar fusion were evaluated with dynamic radiographs and MRI. ASD was classified anatomically as proximal (86.3%), distal (12.1%, or combined (1.5%) and, sub-classified pathologically into six sub-types: Type 1: Disc prolapse (17.4%), Type 2: Disc degeneration with intra-discal instability (15.1%), Type 3: Anterolisthesis and facet instability (6.8%), Type 4: Retrolisthesis (25%), Type 5: Stenosis (21.9%) and Type 6: Combined types (13.6%).

RESULTS

The mean duration between the index surgery and ASD was 5.9 ± 4.1 years. Surgery was required in 40.9% (54/132). Six factors were highly predictive of surgical treatment for ASD, viz., Diabetes mellitus (OR-4.3, p = 0.007), ASD- disc prolapse (OR 6.3, p = 0.018), ASD intra-discal instability (OR-16.8206, p = 0.003), ASD - anterolisthesis (OR - 8.2998, p = 0.043), Facet angle > 75° (OR 37.6, p = 0.02) and radiculopathy (OR 48.0, p = 0.002). Retrolisthesis was the most benign type as 84.8% patients were managed conservatively (p = 0.016). Among proximal ASD, retrolisthesis was the most common subtype (28.9%) while disc prolapse was the most common subtype in distal ASD 37.5% (p = 0.032).

CONCLUSION

The study classifies the versatile clinic-radiological presentation of ASD, and identifies factors that predicted the development of the different sub-types of ASD. Knowledge about the six clinic-radiological factors that predict the need for surgical treatment in ASD is beneficial.

Impact of iatrogenic alterations on adjacent segment degeneration after lumbar fusion surgery: a systematic review

PURPOSE

Adjacent segment degeneration (ASDeg) and disease (ASDis) remain significant challenges following lumbar spinal fusion surgery, with reported incidences of 36% for ASDeg and 11% for ASDis within two to seven years post-operation. However, the mechanisms leading to the development of ASDeg are still poorly understood. This comprehensive review aims to elucidate the multifactorial etiology of ASDeg by examining important iatrogenic alterations associated with spinal fusion.

METHODS

A systematic review following PRISMA guidelines was conducted to identify clinical studies quantifying the occurrence of ASDeg and ASDis after lumbar fusion surgery. An EMBASE and citation search up to April 2023 yielded 378 articles. Data extracted encompassed study design, fusion type, sample size, patient age, and incidence of ASDeg and ASDis. A total of 87 publications were analyzed in the context of iatrogenic alterations caused by surgical access (muscle damage, ligament damage, facet joint damage) and instrumentation (fusion angle, immobilization).

RESULTS

Ligament damage emerged as the most impactful iatrogenic factor promoting ASDeg and ASDis development. Similarly, muscle damage had a significant impact on long-term musculoskeletal health, with muscle-sparing approaches potentially reducing ASDis rates. Immobilization led to compensatory increased motion at adjacent segments; however, the causal link to degeneration remains inconclusive. Fusion angle showed low evidence for a strong impact due to inconsistent findings across studies. Facet joint violations were likely contributing factors but not primary initiators of ASDeg.

CONCLUSION

Based on the analyzed literature, ligament and muscle damage are the most impactful iatrogenic factors contributing to ASDeg and ASDis development. Minimally invasive techniques, careful retractor placement, and ligament-preserving decompression may help mitigate these effects by reducing undue muscle and ligament trauma. Although it is not possible to definitively advocate for one or more techniques, the principle of selecting the most tissue-sparing approach needs to be scaled across surgical planning and execution. Further research is necessary to fully elucidate these mechanisms and inform surgical practices to mitigate ASDeg risk.

Biomechanical preservation of lumbar spine stability and motion with an intraosseous implant following vertebral body osteotomy

PURPOSE

When nonsurgical treatments for low back pain with radiculopathy fail to relieve symptoms from nerve root compression, lumbar spine fusion is the standard treatment. A potential new option is using a vertebral body osteotomy (VBO) with the Vertiwedge Intraosseous System™, a novel spinal implant designed to restore foraminal height, spinal alignment, and preserve motion. The purpose was to demonstrate that VBO with the Vertiwedge implant can stabilize and correct collapsed segments while maintaining the spine's native stability and motion under various loading conditions.

METHODS

The Vertiwedge was biomechanically assessed in a novel spine simulator via non-destructive articulations that included randomized compression loads (0-500 N) and planar motions in flexion/extension (20°/18°), lateral flexion (19°), and axial rotation (9°). Simulations were conducted on 8 cadaveric specimens (5 M:3 F, spinal segments L1-S1, ages 35-75 years). A cubic fit model compared equivalence and linear mixed model compared stiffness with covariates of condition, motion, and compression. Change in foraminal height was not addressed as cadaveric specimens were non-pathological.

RESULTS

After surgical implantation, the cubic fit model demonstrated an overall equivalence (60-80%) to the Native condition. The mixed model demonstrated no differences in maximum moments between any conditions (p ≥ 0.067) or condition*motion (p ≥ 0.196). The full interaction (condition*motion*compression) demonstrated no differences of biomechanical stiffness (p ≥ 0.991).

CONCLUSION

The Vertiwedge, after surgical implantation, demonstrated a return of biomechanical stiffness (stability) compared to the native state of the lumbar spine specimen with all three planes of motion across various physiologic compression loads. The Vertiwedge accomplished nearly native stiffness while preserving lumbar spine motion.

Effect of vertebral rotation on adjacent segment degeneration after the early stage of lumbar fusion surgery

OBJECTIVE

Related studies have shown that the torsional vertebral after fused significantly increase adjacent disc stress and accelerate degeneration. This suggests that vertebral rotation (VR) may accelerate adjacent segment degeneration (ASD). To investigate: (1) the correlation between VR and radiographic adjacent segment degeneration (rASD) after the early stage of lumbar fusion (2), the incidence of rASD with different VR degrees (3), whether the incidence of rASD can be reduced by surgically reducing instrumented vertebrae (IV) rotation.

METHODS

A retrospective analysis was conducted on the cases of 195 patients with lumbar degenerative disease (LDD) who were selected based on inclusion and exclusion criteria. The grade and angle of VR were measured for accurate analysis. The final follow-up evaluated the clinical improvement of the patients and the rASD. The impact of various factors on rASD was observed using univariate and multivariate logistic regression analyses. With different VR grades, Kaplan-Meier survival analysis was used to describe the incidence of rASD at various follow-up intervals.

RESULTS

The results indicate that preoperative adjacent vertebrae (AV) rotation (OR = 1.852, 95% CI = 1.064-3.224, P = 0.029) and IV rotation at final follow-up (OR = 2.748, 95% CI = 1.458-5.177, P = 0.002) are the independent risk factors for rASD. The results of the Kaplan-Meier analysis showed that with different VR grades, the follow-up period was different when the cumulative incidence of rASD reached 50%. The AV rotation decreased in the patients whose IV rotation decreased after the operation (P < 0.001), and the incidence of rASD was also lower (P = 0.004), especial in the fused to S1 group.

CONCLUSIONS

VR is a risk factor for rASD at the early stage of lumbar fusion surgery. Reducing VR during surgery can alleviate the speed of ASD and reduce the incidence of rASD in fused to S1.

Impact of spinal alignment on adjacent segment disease and degeneration after short-segment lumbosacral fusion

BACKGROUND CONTEXT

Adjacent segment disease (ASDis) and degeneration (ASDeg) are common complications following lumbar fusion, ranging from asymptomatic radiographic changes to debilitating symptoms requiring revision surgery. While the impact of spinopelvic alignment (SPA) on postoperative outcomes and ASDis prevention is well-studied in long-construct fusions, its role in short-segment lumbosacral fusions, particularly over the long term, remains unclear.

OBJECTIVE

This study aimed to investigate the association between global and distal lumbar SPA with the development of ASDis and ASDeg in the long-term follow-up of patients undergoing short-segment lumbosacral fusion. Secondary outcomes were patient reported outcome measures (PROMs) in relation to adjacent segment changes.

STUDY DESIGN/SETTING

Retrospective single-center cohort study with minimum follow-up of 5 years.

PATIENT SAMPLE

A total of 86 patients who underwent L4-S1 spinal fusion between 2003 and 2015, with a mean follow-up of 12±4 years.

OUTCOME MEASURES

The primary outcome was the development of adjacent segment changes, classified into 2 groups: (1) surgically-treated ASDis, and (2) ASDeg, defined as radiographic evidence of adjacent segment changes without surgical intervention. Secondary outcomes included PROMs: the Oswestry Disability Index (ODI) and the European Quality of Life 5 Dimensions 5 Level (EQ5D5L).

METHODS

Pre- and postoperative standing radiographs were annotated and the following global lumbar SPA parameters analyzed: Pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), lumbar lordosis (LL), PI-LL-mismatch, lumbar pelvic angle (LPA). Additionally, the following distal lumbar SPA parameters were analyzed: Distal lordosis (DL) between L4-S1, lordosis distribution index (LDI=DL/LL), PI-DL-difference, DL-PI-ratio, adjacent segment lordosis (ASL). Postoperative ODI and EQ5D5L were assessed via a telephone interview.

RESULTS

Among 86 patients with a mean follow-up of 12±4 years the incidence of ASDis was 27.9% (n=24), while 7.0% (n=6) showed ASDeg. No significant differences in pre- and postoperative global lumbar SPA were found in patients who developed ASDis or ASDeg compared to patients who did not. PI (53.6° vs. 59.6°) and preoperative SS (34.9° vs. 40.3°) trended to be lower in the ASDis group compared to controls, although non-significant. Pre- and postoperative distal lumbar SPA parameters did not differ between groups. Patients with adjacent segment changes, regardless of whether they underwent revision surgery, reported worse PROMs. ODI scores were elevated in both the ASDis group (28, IQR 15-42) and the ASDeg group (34, IQR 14-47) compared to controls (10, IQR 2-24; p=.005). EQ5D5L scores were lower in both the ASDis (70, IQR 53-83) and the ASDeg groups (60, IQR 55-85) compared to controls (85, IQR 75-90; p=.025).

CONCLUSION

In this long-term follow-up study of patients undergoing short-segment lumbosacral fusion, neither preoperative nor postoperative SPA was significantly associated with the development of ASDis or ASDeg. These findings suggest that other factors may have a greater influence on ASDis risk. Patients who developed adjacent segment changes, whether or not they required revision surgery, experienced worse long-term postoperative PROMs, indicating the importance of ASDis prevention.

Correction of L5 Tilt in 2-Row Vertebral Body Tethering Versus Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis

STUDY DESIGN

Single-center retrospective cohort study.

OBJECTIVE

To compare the correction of fractional curve and L5 tilt in 2RVBT versus PSF with LIV in the lumbar spine.

SUMMARY OF BACKGROUND DATA

Vertebral body tethering, an AIS fusion-alternative, avoids rigid constructs, allowing for lower instrumented vertebra (LIV) selection. Single-tether constructs break, but mini-open thoracoscopic assistant double-row vertebral body tethering (2RVBT) reduces this. Limited comparative studies exist with posterior spinal fusion (PSF).

METHODS

Retrospective analysis of AIS correction surgeries with lumbar LIV using preoperative and minimum 2-year postoperative imaging. Patients were divided into 2RVBT or PSF groups. Data included age, Riser, UIV, LIV, instrumented levels, and revision rates. Radiographic analyses included preoperative and postoperative main curve Cobb (MCC), secondary curve Cobb (SCC), fractional curve Cobb (FCC), and L5 tilt.

RESULTS

Ninety-nine patients participated (49 in 2RVBT, 50 in PSF). Preoperatively, secondary CC differed significantly (2RVBT: 44.6±10.4 degrees vs. PSF: 39.5±11.8 degrees, P =0.026), but not L5 tilt, MCC, or FCC. Postoperatively, MCC (2RVBT: 25.7±12.3 degrees vs. PSF: 19.5±7.4 degrees, P =0.003) and SCC (2RVBT: 18.0±8.4 degrees vs. PSF: 14.5±6.6 degrees, P =0.012) varied. Preoperative to postoperative changes in MCC (2RVBT: -32.0±11.3 degrees vs. PSF: -37.2±13.3 degrees, P =0.044) and L5 tilt (-13.8±9.0 degrees vs. PSF: -8.1±6.8 degrees, P =0.001) differed. Revision rates were similar (2RVBT: 2.0%, PSF: 4.0%, P =0.57). In 2RVBT, 3 tethers broke, 1 revision occurred for a broken tether, and 1 pleural effusion needed thoracocentesis. In PSF, 1 superficial infection needed surgery, and 1 revision was for add-on phenomenon. After PSM for Lenke classification, 54 patients remained (27 in each group). At 2 years, 2RVBT showed less MCC correction (-30.8±11.8 degrees vs. -38.9±11.9 degrees, P =0.017), but greater L5 tilt correction (-14.6±10.0 degrees vs. -7.5±6.0 degrees, P =0.003).

CONCLUSIONS

This study with a minimum 2-year radiographic follow-up demonstrates that 2RVBT results in greater L5 tilt correction when compared with posterior spinal fusion after PSM for Lenke classification and similar rates of revision surgery.

LEVEL OF EVIDENCE

Level III.

Advantages of Combined Use of Claw Hooks and Sublaminar Wires as the Upper Foundation of Long Fixation from the Thoracic Spine to the Pelvis in Osteoporotic Cases: A Finite Element Analysis of Proximal Junction Stress

Introduction

This study aimed to compare the biomechanical stress at the proximal junctional aspect between the conventional pedicle screw (PS) fixation (PSF) and the low PS density fixation (LPF) method.

Methods

This study involved 10 patients, half of whom have non-osteoporosis and the other half have osteoporosis. We made two types of intact models (one is from the upper thoracic-to-pelvis model, and the other is from the lower thoracic-to-pelvis model). From the intact models, we constructed two kinds of fusion models: (1) PSF and (2) LPF. The LPF method was as follows: The claw hooks (the combination of the down-going transverse process hooks and facet hooks) were set at the upper instrumented vertebra (UIV) and sublaminar wires at the thoracic spine and PSs at the lumbo-pelvis.

Results

Upper thoracic to pelvis fixation model In non-osteoporosis, no significant difference between the PSF and LPF is found. In osteoporosis, the von Mises stresses of the vertebra body at UIV, UIV+1, and disc were significantly lower in LPF than in PSF. Lower thoracic-to-pelvis fixation model In non-osteoporosis, the average von Mises stress of the vertebral body at UIV+1 and the maximum stress at UIV were lower in LPF than in PSF; however, no significant difference was found in the others. In osteoporosis, the von Mises stress was significantly lower in LPF than in PSF.

Conclusions

The claw hooks stabilized the vertebra body at UIV firmly, and sublaminar wires reduced load translation from the fixed spine.

Biomechanical effects of screw loosening after lumbar PEEK rod and titanium rod fixation: a finite element analysis

Objective

Screw loosening is a common complication following lumbar spine fixation surgery, yet the biomechanical outcomes after screw loosening remain rarely reported. This study aims to utilize finite element (FE) models to compare the biomechanical performance of PEEK rod dynamic fixation and titanium rod rigid fixation in the postoperative lumbar spine, exploring potential biomechanical mechanisms for re-stabilization of loosened screws.

Methods

A FE model of the lumbar spine from L3 to the sacrum was developed using CT image segmentation. Four L4-S1 fixation models were constructed: PEEK rod dynamic fixation (PEEK model), titanium rod rigid fixation (titanium model), PEEK rod with pedicle screw loosening (PEEK-PSL model), and titanium rod with pedicle screw loosening (titanium -PSL model). A preload of 300 N was applied to the superior surface of L3. Stress distributions in the intervertebral discs, facet joints, pedicle screws, and rods were calculated to evaluate the biomechanical effects of different fixation methods.

Results

Across four physiological loading conditions, the stress differences in intervertebral discs, facet joints, and nucleus pulposus between the PEEK model and titanium model were minimal. However, vertebral body stress was significantly higher in the PEEK model, whereas screw and rod stresses were greater in the titanium model. Screw loosening further increased stress in all models. The S1 screw in the PEEK-PSL model exhibited lower and more uniform stress, while stress was concentrated at the screw-rod junction in the titanium-PSL model.

Conclusion

The PEEK rod fixation system demonstrated superior stress distribution, reducing stress concentration risks and improving stability while minimizing screw loosening rates. In contrast, the titanium rod system offers advantages in scenarios requiring high rigidity, potentially making it more suitable for patients with greater stability needs.

Complications and reoperations in young versus old patients undergoing cervical disc arthroplasty

Background

Despite the growing popularity of cervical disc arthroplasty (CDA), there remains a lack of literature investigating outcomes in older patients and no consensus exists on an age threshold beyond which CDA is not recommended. This study aimed to compare outcomes between patients younger than 65 and those aged 65 and older undergoing CDA.

Methods

Patients who underwent CDA at a major spine center (January 2009-December 2023), with at least 1 year of follow-up, were included. Two age-based cohorts were analyzed: younger (<65) and older (≥65). Both single and multilevel disc replacements were considered. Primary outcomes included comparing 90-day complications and all-cause reoperation rates in the 2 cohorts. Secondary outcomes included comparisons of patient characteristics, operative data, and length of stay (LOS). Frequencies, chi-squared analysis, and Student's t-test were used to compare cohorts.

Results

A total of 298 CDAs were evaluated among 188 patients. There were 132 patients in the younger cohort (mean age: 48.9±10.2) and 56 in the older cohort (mean age: 69.5±3.8). Cohorts were similar with regards to body mass index, sex, and length of follow up. The overall 90-day complication rate was 23.8%. There was no difference in complication rates (younger: 23.3%, older: 25.0%, p=.60). Older cohort averaged more levels operated (older 1.8±0.6, younger 1.5±0.7, p=.006). The overall reoperation rate was 12.2% (young: 13.5%, older: 8.9%, p=.38). Subsidence was the most common cause of reoperation in both the younger (n=4, 3.0%) and older (n=2, 3.6%) cohorts.

Conclusion

In this series, we found no statistically significant differences in 90-day complication or reoperation rates between younger (<65 years) and older (≥65 years) patients undergoing CDA. Subsidence emerged as the most common complication, occurring at similar rates in both cohorts. While further large-scale, long-term analysis is warranted to determine clinical outcomes of CDA in older patients, this study provides comparable complication and reoperation rates as in the younger population.

Association between paraspinal muscle quality and surgery for adjacent segment disease

Background

Adjacent segment disease (ASD) is one of the most common complications after spinal fusion. There are several risk factors for ASD, but recently the quality of the paraspinal musculature has been implicated as a potential risk factor. The purpose of this study is to examine the association between paraspinal muscle degeneration and risk of surgery for ASD.

Methods

We conducted a retrospective review of spinal fusion patients at our institution from 2009 to 2022 who underwent subsequent surgery for ASD. Inclusion criteria included patients aged 18 and older at time of index operation. Control cohort included patients who did not undergo subsequent surgery for adjacent segment disease with a minimum one year follow up. Patients were matched based on age, gender, and BMI. We measured paraspinal fat percentage and circumferential surface area (CSA) at L3 and at the proximal end of their future construct. Paraspinal fat percentage and CSA were measured using ImageJ (National Institutes of Health, Bethesda, Maryland, USA). Student T-test was used to evaluate for statistically significant differences with p-value ≤ .05.

Results

A total of 154 patients were reviewed with 77 patients in each cohort. The average age and BMI in the control group was 61.3 and 30.0 versus 61.2 and 29.6 in patients who underwent subsequent surgery. Overall, patients who underwent surgery for adjacent segment disease had 24% higher paraspinal fat percentage at L3 (13.8 ± 7.7% vs. 11.1 ± 6.5%, p-value = .02) and 22% higher paraspinal fat percentage at the top end of their construct (16.0 ± 9.0% vs. 13.1 ± 7.1%, p-value = .03).

Conclusions

Our study found that patients who undergo surgery for adjacent segment disease have 24% higher fat percentage in their paraspinal musculature at L3 and 22% higher fat percentage at the proximal end of their fusion construct.

Clinical Outcomes and Patient Perspectives in Full Endoscopic Cervical Surgery: A Systematic Review

OBJECTIVE

Full endoscopic cervical surgery (FECS) is an evolving minimally invasive approach for treating cervical spine disorders. This systematic review synthesizes current evidence on the clinical outcomes and patient perspectives associated with FECS, specifically evaluating its safety, efficacy, and overall patient satisfaction.

METHODS

A systematic search of the PubMed/MEDLINE, Cochrane Library, Embase, and Web of Science databases was conducted following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Studies published between January 2000 and September 2024 that reported on clinical outcomes or patient perspectives related to FECS were included. Risk of bias was assessed using the ROBINS-I (Risk Of Bias In Non-randomized Studies - of Interventions) tool and the Cochrane Risk of Bias tool. Inclusion criteria encompassed randomized controlled trials, prospective cohort studies, retrospective studies, and observational studies focused on adult populations undergoing FECS for cervical spine surgery.

RESULTS

The final synthesis included 30 studies. FECS was associated with significant reductions in both cervical and radicular pain, as well as meaningful functional improvements, measured by standardized clinical scales such as the Neck Disability Index and visual analogue scale. Patient satisfaction rates were consistently high, with most studies reporting satisfaction exceeding 85%. Complication rates were low, primarily involving transient neurological deficits that were typically resolved without the need for further intervention. Nonrandomized studies generally presented a moderate risk of bias due to confounding and selection, whereas randomized controlled trials exhibited a low risk of bias.

CONCLUSION

FECS is a safe and effective minimally invasive surgical option for cervical spine disorders associated with substantial pain relief, functional improvement and high levels of patient satisfaction.

Safety and efficacy of cervical foraminotomy versus anterior cervical discectomy and fusion for 1-2 level radiculopathy

Background

Cervical foraminotomy (CF) and anterior cervical discectomy and fusion (ACDF) are both used to treat 1-2 level cervical radiculopathy. We evaluated demographic and Patient-Reported Outcomes Measurement Information System (PROMIS) to match cohorts and compare the safety/efficacy of performing CF versus ACDF for 1-2 level unilateral radiculopathy.

Methods

This was a retrospective review of 64 patients with similar clinical and radiological data that underwent 1-2 level unilateral CF versus ACDF for cervical radiculopathy. Variables studied included operative revision rates, adverse events, surgical costs, postoperative imaging, PROMIS scores, numeric pain scores, incidence of dysphagia, frequency of vocal cord paralysis, and postoperative neurological status.

Results

We found no clinical or radiological differences between patients undergoing ACDF versus CF for unilateral 1-2 level cervical radiculopathy. Surgical differences were observed; ACDF patients demonstrated a 6.25% revision rate versus 0% for CF patients, 40% of ACDF patients reported mild dysphagia versus 0% for CF, 3% undergoing ACDF exhibited vocal cord paralysis versus 0% for CF, and ACDF incurred high implant costs (i.e., $1,836.37 and $2,773.44 for one- and two-level ACDFs) versus 0% for CF warranting no implants.

Conclusion

Patients undergoing CF versus ACDF for 1-2 level unilateral cervical radiculopathy required 3.70 fewer postoperative X-rays, 40 min less operative time, and 10.95-h shorter lengths of hospital stay (P < 0.001). Alternatively, ACDF patients had a 31.3% greater probability of achieving a minimum clinically important difference in PROMIS pain interference scores but incurred a 6.25% reoperation rate, a 40% incidence of dysphagia, and high implant costs versus 0% for CF.

Effect of hybrid screw placement technique on adjacent segment degeneration: a finite element analysis

The biomechanical properties of the lumbar pedicle screw technique, cortical bone trajectory screw technique, and modified cortical bone trajectory screw technique when used individually in internal fixation systems and their effects on neighboring segments have been studied. However, there are fewer studies on the combined use of the modified cortical bone trajectory screw technique and the cortical bone trajectory screw technique. This paper focuses on analyzing the stresses in the internal fixation system when the modified and traditional cortical bone trajectory screw techniques are applied jointly, and the effects on the adjacent segments using the finite element analysis.

MRI after Cervical Spine Decompression and Fusion Surgery: Technical Considerations, Expected Findings, and Complications

Cervical spine MRI is essential for evaluating potential complications and symptomatic degenerative changes following cervical decompression and fusion surgery. High-yield diagnostic interpretation considers the underlying surgical approach (anterior vs posterior), the time elapsed since surgery, and the clinical status of the patient to reliably differentiate expected postoperative changes from surgical complications. As cervical anatomy, such as the foramina and nerve roots, is smaller than that of the lumbar spine, MRI acquisition challenges include the demand for higher spatial resolution. Another unique challenge for cervical spine MRI is susceptibility to motion artifacts from swallowing, breathing, and cerebrospinal fluid pulsation. Modified MRI protocols, including the use of metal artifact suppression techniques, can help mitigate susceptibility artifacts from metallic implants. This focused review of postoperative cervical spine MRI discusses common cervical surgery decompression and fusion approaches and recommended MRI acquisition and interpretation algorithms, briefly considers radiofrequency coil selection, and illustrates complications in both early and delayed phases.

Risk factors and treatment strategies for adjacent segment disease following spinal fusion (Review)

Adjacent segment disease (ASD) is a significant clinical complication following cervical and lumbar spinal fusion surgery, characterized by the degeneration of spinal segments adjacent to the fused area. The present literature review aimed to elucidate the risk factors contributing to ASD and to evaluate current and emerging treatment strategies. Epidemiological data indicate that patient‑related factors such as age, pre‑existing spinal degeneration and comorbidities, along with surgical factors including the type of fusion, instrumentation and alignment correction, play pivotal roles in ASD development. Biomechanical alterations post‑fusion further exacerbate the risk. The underlying mechanisms of ASD involve changes in spinal kinematics and disc degeneration, driven by inflammatory and degenerative processes. Diagnostic modalities, such as magnetic resonance imaging and computed tomography scans, are essential for early detection and accurate diagnosis. Preventive strategies emphasize meticulous preoperative planning, advanced surgical techniques and postoperative rehabilitation. Treatment approaches range from conservative methods such as physical therapy and pharmacological interventions to surgical solutions, including revision surgeries and the use of motion‑preserving technologies. Emerging therapies, particularly in regenerative medicine, show promise in mitigating ASD. The present review underscored the necessity of a multidisciplinary approach to optimize patient outcomes and highlighted the need for ongoing research to address gaps in the current understanding of ASD in both cervical and lumbar regions.

Efficacy and safety of long fusion versus short fusion in degenerative scoliosis: a systematic review and meta-analysis

BACKGROUND

This study aimed to evaluate the efficacy and safety of long fusion versus short fusion in patients with degenerative scoliosis.

METHODS

Databases were systematically searched up to June 2024. The authors applied Review Manager 5.4 to manage the data and perform the analysis.

RESULTS

After the selection of 611 studies from electronic databases, 13 studies were eligible for inclusion. These 13 studies included 1261 patients: 534 patients underwent long fusion, and 727 underwent short fusion. At baseline, the Cobb angle, coronal imbalance, and sagittal imbalance were greater in the long fusion group. There was no difference in the VAS back, Cobb angle, ODI, hospital stay, revision surgery, adjacent segment degeneration, sacral slope, pelvic tilt, Cobb angle, lumbar lordosis, coronal balance, or sagittal balance at the final follow-up. The surgery time, complication rates, and amount of blood loss were greater in the long fusion group.

CONCLUSIONS

Long fusion leads to superior radiographic improvement, particularly in reducing the Cobb angle and reconstructing coronal and sagittal balance. The long fusion group was inferior in terms of increased surgical time, more blood loss, and higher postoperative complication rates. At the final follow-up, there was no difference in the clinical or radiographic outcomes between the long and short groups. For patients with a large coronal Cobb angle and significant coronal or sagittal imbalance, long fusion surgery should be performed. On the other hand, for patients whose milder deformities and clinical symptoms are the main concern, short fusion surgery is recommended.

Does Restoration of Lumbar and Segmental Cobb Angle Affect Fusion Outcome in Short-Segment Posterior Lumbar Fusion?

OBJECTIVE

To study the effect of lumbar lordosis change and pelvic parameters on surgical outcomes such as fusion versus nonfusion (pseudarthrosis), adjacent segment pathology (ASP), and reoperation in patients undergoing 1-level, 2-level, and 3-level posterior lumbar fusion (PLF).

METHODS

Adult patients with degenerative spine disease who had undergone PLF between L2 and L5 levels at an academic center between 2010 and 2020 were included. Preoperative and early postoperative lateral standing radiographs of the lumbar spine were used to measure preoperative lumbar Cobb angle, postoperative lumbar Cobb angle, preoperative segmental Cobb angle (measured from the superior end plate of the upper instrumented vertebra to the inferior end plate of the lower instrumented vertebra), postoperative segmental Cobb angle, preoperative pelvic incidence, and pelvic tilt. Change in lumbar and segmental Cobb angle was calculated as postoperative Cobb angle (lumbar and segmental) minus preoperative Cobb angle.

RESULTS

A total of 243 patients met our inclusion and exclusion criteria. Patients who had pseudarthrosis had significantly less restoration of lumbar lordosis compared with those who did not, both for lumbar Cobb angle change (-5.2 ± 8.2 vs. -0.2 ± 8.2; P = 0.01) and segmental Cobb angle change (-5.4 ± 6.6 vs. -1.5 ± 6.0; P = 0.01). Moreover, pelvic incidence was lower in patients who developed ASP versus those who did not. There was no significant difference in these measures (lumbar Cobb angle changes and segmental Cobb angle change) in patients who experienced ASP and those who did not.

CONCLUSIONS

Better restoration of lumbar lordosis reduces rates of pseudarthrosis after short-segment PLF but has no association with rates of ASP.

Clinical Outcomes After 1 and 2-Level Lumbar Total Disc Arthroplasty: 1,187 Patients with 7 to 21-Year Follow-up

BACKGROUND

In this study, we expand the supportive evidence for total disc arthroplasty (TDA) with results up to 21 years in a large patient cohort who received a semiconstrained ball-and-socket lumbar prosthesis. The objectives of the study were to compare the results for 1 versus 2-level surgeries and to evaluate whether prior surgery at the index level(s) impacts clinical outcomes.

METHODS

From 1999 to 2013, 1,187 patients with chronic lumbar degenerative disc disease (DDD) underwent lumbar TDA, of whom 772 underwent a 1-level procedure and 415 underwent a 2-level procedure. A total of 373 (31.4%) of the 1,187 patients had prior index-level surgery. Patients were evaluated preoperatively; at 3, 6, 12, 18, and 24 months postoperatively; and yearly thereafter. The follow-up duration ranged from 7 to 21 years (mean, 11 years and 8 months). Collected data included radiographic, neurological, and physical assessments, as well as self-evaluations using the Oswestry Disability Index (ODI) and visual analog scale (VAS) for back and leg pain. Perioperative data points, complication rates, and reoperation or revision rates were also assessed. Patients were divided into 4 groups: 1-level TDA with no prior surgery at the index level, 1-level TDA with prior surgery, 2-level TDA with no prior surgery, and 2-level TDA with prior surgery.

RESULTS

All groups showed dramatic reduction in the ODI at 3 months postoperatively and maintained these scores over time. Although VAS pain did not diminish to its final level as rapidly for patients with prior surgery, there was no significant difference between the groups in terms of pain reduction at 24 months postoperatively. Of 1,187 patients, 49 (4.13%) required either a new surgery at another level or revision or reoperation at the index level. Rates were too low in all groups to compare them statistically. Total TDA revision and adjacent-level surgery rates over 7 to 21 years were very low (0.67% and 1.85%, respectively).

CONCLUSIONS

This study demonstrates the robust long-term clinical success of 1 and 2-level lumbar TDA as assessed at 7 to 21 years postoperatively in one of the largest evaluated cohorts of patients with TDA. Patients had dramatic and maintained reductions in disability and pain scores over time and low rates of index-level revision or reoperation and adjacent-level surgery relative to published long-term fusion data. Additionally, patients who underwent 1-level lumbar TDA and those who underwent 2-level TDA demonstrated equivalent improvement, as did patients with prior surgery at the index level and those with no prior surgery.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Is posterior cervical imbalance after anterior cervical discectomy with fusion a determinant in the development of adjacent cervical degeneration? A retrospective study with an average of 8 years of follow-up

Aims

The primary objective of this study is to evaluate the hypotheses that postoperative sagittal imbalance influences the development of adjacent segment degeneration (ASDeg) in patients who have undergone an anterior cervical discectomy with fusion (ACDF).

Settings and Design

This was a retrospective cohort study.

Subjects and Methods

We analyzed 63 patients with ACDF with a minimum of 2 years of follow-up. In the imaging evaluation, sagittal balance parameters were included, as well as radiographic parameters that target the development of ASDeg. In addition, discrimination was made between arthrodesis techniques.

Statistical Analysis Used

Categorical variables were compared using the Chi-square test and Fisher's exact test. Continuous variables were compared using t-test when the data were normally distributed and Wilcoxon tests when the distribution was not normal.

Results

Patients with postoperative imbalance presented with radiographic ASDeg at a rate of 26% (n = 5) versus 22% (n = 9) in patients with postoperative balance, this difference was not significant (P = 0.7). In those who underwent surgery with plate, we found that 23% (n = 4) developed ASDeg versus 22% (n = 1) of patients with anterior cervical arthrodesis with cage-plate and 27% (n = 10) of patients who underwent interbody device surgery, with this difference being nonsignificant (P = 0.7).

Conclusion

We concluded that neither postoperative imbalance nor the type of arthrodesis in patients undergoing ACDF for degenerative pathology showed a positive correlation with the development of radiographic cervical ASDeg at an average follow-up of 8 years.

Is ABO blood type a risk factor for adjacent segment degeneration after lumbar spine fusion?

PURPOSE

This study aimed to explore associations between ABO blood type and postoperative adjacent segment degeneration/disease (ASD) following lumbar spine fusion, as well as evaluate differences in spinopelvic alignment, perioperative care, postoperative complications, and patient-reported outcome measures (PROMs).

METHODS

An ambispective study was performed. Patients who underwent posterolateral or posterior lumbar interbody fusion were included. Demographic, perioperative and postoperative, clinical, and blood type information was recorded. Pre- and post-operative radiographic imaging was analyzed for alignment parameters and development of ASD.

RESULTS

445 patients were included, representing O+ (36.0%), O- (5.2%), A+ (36.2%), A- (6.3%), B+ (12.1%), B- (1.6%), and AB+ (2.7%) blood types. Most patients were female (59.1%), and had a mean age of 60.3 years and BMI of 31.1 kg/m2. Postoperatively, groups did not differ in duration of the hospital (p = 0.732) or intensive care unit (p = 0.830) stay, discharge disposition (p = 0.504), reoperation rate (p = 0.192), or in-hospital complication rate (p = 0.377). Postoperative epidural hematoma was most common amongst A + patients (p = 0.024). Over a mean of 11.0 months of follow-up, all patients exhibited similar improvement in PROMs, with 132 (29.7%) patients developing radiographic evidence of ASD. B + patients were significantly more likely than A + and O + patients to develop spondylolisthesis and ASD (p < 0.05). No significant differences in sagittal alignment parameters and number of levels of fusion were found (p > 0.05).

CONCLUSIONS

This is the first large-scale study to address and demonstrate proof-of-principle that ABO blood type, a non-modifiable risk factor, is associated with ASD following lumbar spine fusion.

Crossing the Cervicothoracic Junction: A Biomechanical Investigation of C7 Versus T1 Caudal Selection's Effect on Adjacent Segment Motion in Posterior Cervical Fusion

STUDY DESIGN

A biomechanical study.

OBJECTIVE

This study aims to evaluate the biomechanical adjacent segment effects of multilevel posterior cervical fusion constructs that terminate at C7 compared with those that terminate at T1 in cadaveric specimens.

BACKGROUND

The cervicothoracic junction poses unique challenges for spine surgeons. Deciding to terminate multilevel posterior cervical fusion constructs at C7 or extend them across the cervicothoracic junction remains a controversial issue.

METHODS

Six cadaveric specimens underwent biomechanical testing in the intact state and after instrumentation with constructs from C3 and terminating at either C7 or T1. Range of motion (ROM) was assessed in flexion-extension, lateral bending, and axial rotation globally and at cranial and caudal adjacent segments.

RESULTS

There was a significant decrease in overall flexion/extension by both C7 (-35.5°, P =0.002) and T1 (-39.8°, P =0.002) instrumentation compared with the intact spine. T1 instrumentation had significantly lower (-4.3°, P =0.008) flexion/extension ROM compared with C7 instrumentation. There were significant decreases in axial rotation by both C7 (-31.4°, P =0.009) and T1 (-36.8°, P =0.009) instrumentation compared with the intact spine, but no significant differences were observed between the 2. There were also significant decreases in lateral bending by both C7 (-27.9°, P =0.022) and T1 (-33.7°, P =0.022) instrumentation compared with the intact spine, but no significant differences were observed between the 2. No significant differences were observed in ROM at cranial or caudal adjacent segments between constructs terminating at C7 and those extending to T1.

CONCLUSION

This biomechanical investigation demonstrates that constructs that cross the cervicothoracic junction experience less overall spinal motion in flexion-extension compared with those that terminate at C7. However, contrary to prior studies, there is no difference in cranial and caudal adjacent segment motion. Surgeons should make clinical decisions regarding the caudal extent of fusion in multilevel posterior cervical fusions without major concerns about adjacent segment motion.

Does Position of Pedicle Screws Correlate With Adjacent Segment Degeneration? An Average 6-Year Follow-Up Retrospective Study

STUDY DESIGN

Retrospective case serie.

OBJECTIVES

Assess the correlation between pedicle screw (PS) position of the first instrumented vertebra (FIV) with proximal adjacent segment degeneration (ASD) development or progression.

METHODS

Patients ≥55 years who have undergone lumbar fusion with a minimum 2-year follow-up were included. Radiographic PS position was assessed by the angle between the first PS and the upper vertebral endplate (VE) and by the PS tip-VE distance. Radiographic parameters of ASD included: disc height, disc angle, and vertebral listhesis. ASD magnetic resonance imaging (MRI) parameters included: disc degeneration and lumbar stenosis. ROC curve analysis was performed to identify the best cut-off points in correlation with lumbar stenosis.

RESULTS

Forty-eight patients were included with an average follow-up of 6 years. All 48 included patients developed some degree of ASD whether on radiographic or MRI parameters. PS tip-VE distance and PS-VE angle were both positively correlated with: (1) Delta (Δ) lumbar stenosis; (2) Δ Disc degeneration; and (3) Δ Disc height. ROC curve analysis correlating PS tip-VE distance and PS-VE angle with an increase in the canal stenosis severity ≥2° resulted in a cut-off point of 36% and 9.5°, respectively.

CONCLUSIONS

The cranial orientation (PS-VE angle) of the pedicle screw in the first instrumented vertebra, along with a shorter pedicle screw tip-vertebral endplate distance (PS tip-VE), positively correlated with ASD progression at an average 6-year follow-up. Protective values against lumbar stenosis were identified as a PS tip-VE distance ≥36% of the first instrumented vertebra height and a PS-VE angle ≤9.5° relative to the upper vertebral endplate.

The Importance of Preserving the Posterior Ligament Complex in Elective Lumbar Fusion Surgery: Early Results from a Single-Center Experience

BACKGROUND

 Adjacent segment disease (ASD) is a degenerative condition at the segment adjacent to a previously fused segment. Potential risk factors for ASD, such as posterior ligamentous complex (PLC) integrity between the upper instrumented vertebra (UIV) and the first unfused segment (UIV+1), have not been addressed. The objective of this study is to assess the PLC integrity between the UIV and UIV+1 following posterior lumbar decompression and fusion (PLDF).

METHODS

 A retrospective review of 122 patients who received a PLDF was performed. Patients were divided into groups based on the integrity of the PLC between the UIV and the UIV+1: PLC disrupted and PLC intact. The development of ASD was assessed using standard radiographic parameters, and reoperation rates were reviewed.

RESULTS

 Radiographic indicators for ASD were more common in patients of the PLC-deficient group-D and showed significantly higher mobility at the UIV+1 (p < 0.05). The overall surgical revision rate due to ASD was 7.4%, with group D (28 patients) exceeding the revision rate of group I (94 patients) by 4.3% (10.7% vs. 6.4%) over a mean follow-up of three years. The mean return to the operative report time at the UIV+1 was 2.4 years (± 1.7 years) after index surgery.

CONCLUSION

 We demonstrated a significant increase in mobility at the UIV+1 in lumbar fusion in patients with disrupted PLC. PLC deficiency at UIV+1 appears to contribute to the development of ASD through instability and is implicated in higher surgical revision rates.

Long-term outcomes of spinal fusion in adolescent idiopathic scoliosis: a literature review

Adolescent idiopathic scoliosis (AIS) is the most common form of spinal deformity in the younger population. The surgical management for these patients improved constantly over the last year and might not be comparable to modern treatment strategies. However, under this aspect the present investigation updates and discusses current evidence regarding the long-term outcome of the surgical management of AIS. All the clinical studies which evaluated the long-term outcomes of spinal fusion were considered. Level of evidence, clinical and radiological data, results of health-related questionnaires and surgery-associated complications during long-term follow-up, e.g., proximal and distal junctional kyphosis (PJK/DJK), and adjacent segment degeneration (ASD), are presented. Data concerning the following patient-reported outcomes measures were collected: Oswestry Disability Index (ODI), Scoliosis Research Society (SRS) Outcome Questionnaire, visual analogue scale (VAS), and short form-12 and 36 (SF-12/SF-36). Overall, data from 1115 patients were included. Of them, 324 underwent anterior and 791 posterior spinal fusion. One study focuses on a combined anterior/posterior fusions. The mean follow-up was 22.6 years (posterior fusion: 24.6 years, anterior fusion: 18.31 years). Seven studies focus on the thoracic segments, while 12 focus on the lumbar spine. Data on imaging was reported in 13 studies and those on PROMs in 15 investigations. In conclusion, there is low quality and paucity of long-term data on AIS. However, the long-term results of the implicated studies on AIS patients in this review appear to be satisfactory, although there are limitations in the outcome compared to healthy comparison cohorts. Adjacent degenerations appear to be the most common mechanical complication after long-segment fusions, despite their influence on the outcome remains unclear. With regard to pregnancies, there are slightly increased cesarean section rates, which could be explained by deviations in the sagittal profile.

Evaluating the effectiveness of the transcorporeal approach in minimally invasive spine surgery for cervical spinal disease: a comprehensive review and technical insights

BACKGROUND

The evolution of minimally invasive spine surgery, propelled by microscopy and endoscopy techniques, has reshaped the landscape of spinal interventions. The anterior approach to the cervical spine is widely recognized for its reproducibility and effectiveness in treating pathologies leading to radiculopathy or myelopathy. Apart from the traditional transdiscal approach, this study delves into the anterior transcorporeal approach, a minimally invasive technique, exploring its applicability in various cervical spinal pathologies.

PURPOSE

The objective is to comprehensively illustrate the anterior transcorporeal approach, exploring its historical development, biomechanical underpinnings, technical nuances, and clinical applications in managing cervical spine disorders.

METHODS

We conducted a comprehensive review using PubMed, Embase, Cochrane Library, and Web of Science, adhering to PRISMA guidelines. The search was focused on the minimally invasive anterior transcorporeal approach for cervical pathologies, with an emphasis on evaluating the methodological evolution, technical execution, and clinical outcomes across diverse studies.

RESULTS

The review identified a significant body of literature supporting the efficacy of the minimally invasive anterior transcorporeal approach. Over the past two decades, this approach has demonstrated encouraging clinical outcomes, suggesting its potential as an alternative strategy for specific cervical spine diseases. The evolution of this technique is tightly linked to the advancements in medical equipment and the innovative endeavors of surgical pioneers.

CONCLUSIONS

The anterior transcorporeal approach marks a milestone in minimally invasive cervical spine surgery. Its development reflects ongoing efforts to refine surgical techniques for better patient outcomes. While offering a promising alternative for treating certain cervical spine conditions, the approach demands precise case selection and is influenced by the rapid progression of medical technology. Future research and technological advancements are expected to further enhance the efficacy and safety of this approach, potentially expanding its indications in spinal surgery.

Effect of Cervicothoracic Junction LIV Selection on Posterior Cervical Fusion Mechanical Failure: A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review and Meta-analysis.

OBJECTIVE

Analyze and summarize literature evaluating the role of C7, T1, and T2 lowest instrumented vertebra (LIV) selection in posterior cervical fusion (PCF) and if this affects the progression of mechanical failure and revision surgery.

SUMMARY OF BACKGROUND DATA

Literature evaluating mechanical failure and adjacent segment disease in the setting of PCF at or nearby the cervicothoracic junction (CTJ) remains limited with studies reporting conflicting results.

MATERIALS AND METHODS

Two reviewers conducted a detailed systematic review using EMBASE, PubMed, Web of Science, and Google Scholar on June 28, 2021, for primary research articles comparing revision and complication rates for posterior fusions ending in the lower cervical spine (C7) and upper thoracic spine (T1-T2). The initial systematic database yielded 391 studies, of which 10 met all inclusion criteria. Random effects meta-analyses compared revision and mechanical failure rates between patients with an LIV above the CTJ and patients with an LIV below the CTJ.

RESULTS

Data from 10 studies (total sample=2001, LIV above CTJ=1046, and LIV below CTJ=955) were meta-analyzed. No differences were found between the 2 cohorts for all-cause revision [odds ratio (OR)=0.75, 95% CI=0.42-1.34, P <0.0001] and construct-specific revision (OR=0.62, 95% CI=0.25-1.53, P <0.0001). The odds of total mechanical failure in the LIV below CTJ cohort compared with the LIV above CTJ cohort were significantly lower (OR=0.38, 95% CI=0.18-0.81, P <0.0001).

CONCLUSION

The results show patients with PCFs ending below the CTJ have a lower risk of undergoing total mechanical failure compared with fusions ending above the CTJ. This is important information for both physicians and patients to consider when planning for operative treatment.

LEVEL OF EVIDENCE

Level I.

Application of adhesives in the treatment of cartilage repair

From degeneration causing intervertebral disc issues to trauma‐induced meniscus tears, diverse factors can injure the different types of cartilage. This review highlights adhesives as a promising and rapidly implemented repair strategy. Compared to traditional techniques such as sutures and wires, adhesives offer several advantages. Importantly, they seamlessly connect with the injured tissue, deliver bioactive substances directly to the repair site, and potentially alleviate secondary problems like inflammation or degeneration. This review delves into the cutting‐edge advancements in adhesive technology, specifically focusing on their effectiveness in cartilage injury treatment and their underlying mechanisms. We begin by exploring the material characteristics of adhesives used in cartilage tissue, focusing on essential aspects like adhesion, biocompatibility, and degradability. Subsequently, we investigate the various types of adhesives currently employed in this context. Our discussion then moves to the unique role adhesives play in addressing different cartilage injuries. Finally, we acknowledge the challenges currently faced by this promising technology.

Sarcopenia Predicts the Development of Early Adjacent Segment Disease After Transforaminal Lumbar Interbody Fusion

BACKGROUND AND OBJECTIVES

Predicting the development of adjacent segment disease (ASD) after lumbar spine fusion would help guide preoperative and postoperative therapies to prevent reoperation. We sought to evaluate whether sarcopenia predicts the development of early ASD after transforaminal lumbar interbody fusion (TLIF).

METHODS

Retrospective data were collected from 109 patients who underwent TLIF from 2013 to 2023. Patients older than 18 years who underwent elective posterior midline approach TLIF were included. Patients with prior lumbar instrumented fusions, cases of trauma, central nervous system infection, cancer, or long-construct thoracolumbar deformity corrections and those who lacked sufficient follow-up were excluded. The primary outcome was radiographic ASD development within 3 years of surgery. Psoas volumetric measurements were recorded from the most recent preoperative MRI. Odds ratios were calculated with logistic regression analyses.

RESULTS

In 109 patients undergoing elective TLIF, 22 (20.2%) developed ASD within 3 years. Gender, body mass index, and extent of surgery were not associated with ASD development. Multivariate analysis showed left/right psoas cross-sectional area, and psoas:vertebral body ratio (P:VBR) predicted early ASD (P < .0001). Sarcopenia was further categorized as having bilateral P:VBR ≥1 SD below gender mean (T-score -1). Of 18 sarcopenic patients, 15 developed early ASD (83.33%) vs 7 of 91 nonsarcopenic patients (7.69%; P < .0001). Postoperative mismatch between pelvic incidence and lumbar lordosis was predictive of ASD on univariate (P = .0480) but not multivariate analysis. Pelvic tilt and lumbar lordosis postoperatively were not associated with early ASD.

CONCLUSION

Sarcopenia, measured by decreased psoas area and P:VBR, predicts ASD formation within 3 years of surgery. Morphometric analysis of psoas size is a simple tool to identify patients at risk of developing ASD. This information can potentially guide preoperative and postoperative therapies, affect surgical decision making, and effectively counsel patients on risks of reoperation.

Positive Cutibacterium acnes Intervertebral Discs Are Not Associated with Subsidence Following Anterior Cervical Discectomy and Fusion at 3 or 6 Months

Background/Objectives:Cutibacterium acnes (C. acnes), formerly known as Propionibacterium acnes (P. acnes), is an anaerobic, low-virulent bacterium that has been associated with postoperative infections of the shoulder, knee, and cervical spine. Recent studies have highlighted an association between C. acnes and the development of degenerative disc disease (DDD). The aim of this study is to ascertain whether C. acnes increases the risk of subsidence following anterior cervical discectomy and fusion (ACDF). Methods: After IRB approval, consecutive patients undergoing elective ACDF for DDD from 2017 to 2018 were enrolled in this prospective cohort study. Intervertebral disc samples were taken at each affected level and cultured. A total of 66 patients with radiographic follow-ups were included in the final analysis. The extent of subsidence and cervical lordosis was determined immediately postoperatively and at the 3- and 6-month follow-ups. Results: No significant difference in subsidence was observed at 3 months (p = 0.07) or 6 months (p = 0.11) between culture-positive and -negative cohorts. Additionally, there was no significant difference detected in the change in cervical lordosis observed at 3 months (p = 0.16) or 6 months (p = 0.27) between culture-positive and -negative cohorts. For the most inferiorly fused segment, there was a significant difference in subsidence observed at 3 months (1.5 mm, 95% CI: 0.2-2.7 mm, p = 0.02) but not at 6 months (p = 0.17). Conclusions: Intervertebral discs with a positive C. acnes culture were not associated with greater levels of subsidence at 3 or 6 months following ACDF for DDD. Further research is necessary to endorse these results and to gauge the clinical significance of C. acnes infection.

Radiographic Risk Factors for Adjacent Segment Disease Following Anterior Cervical Discectomy and Fusion (ACDF): A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVES

To assess the radiographic risk factors for adjacent segment disease (ASD) following anterior cervical discectomy and fusion (ACDF) for degenerative cervical spine pathologies.

METHODS

PubMed, Embase and the Cochrane Library databases were searched up to December 2023. The primary inclusion criteria were degenerative spinal conditions treated with ACDF, comparing radiological parameters in patients with and without postoperative ASD. The radiographic parameters included intervertebral disc height, cervical sagittal alignment, sagittal segmental alignment, range of motion, segmental height, T1 slope, sagittal vertical axis (SVA), thoracic inlet angle (TIA), and plate to disc distance (PPD). Risk of bias was assessed for all studies. The Cochrane Review Manager was utilized to perform the meta-analysis.

RESULTS

From 7044 articles, 13 retrospective studies were included in the final analysis. Three studies had "not serious" bias and the other 10 studies had serious or very serious bias. The total number of patients in the included studies was 1799 patients. Five studies included single-level ACDF, 2 studies included multi-level ACDF, and 6 studies included single or multi-level ACDF. On meta-analysis, the significant risk factors associated with ASD development were reduced postoperative cervical lordosis (mean difference [MD] = 3.35°, P = .002), reduced last-follow-up cervical lordosis (MD = -3.02°, P = .0003), increased preoperative to postoperative cervical sagittal alignment change (MD = -3.68°, P = .03), and the presence of developmental cervical canal stenosis (Odds ratio [OR] = 4.17, P < .001).

CONCLUSIONS

Decreased postoperative cervical lordosis, greater change in cervical sagittal alignment and developmental cervical canal stenosis were associated with an increased risk of ASD following ACDF.

Anterior vertebral tethering for adolescent idiopathic scoliosis: our initial ten year clinical experience

BACKGROUND

Anterior vertebral tethering (AVT) is a minimally invasive alternative to fusion surgery for adolescent idiopathic scoliosis (AIS) that offers the potential for definitive scoliosis treatment with the possibility of preservation of the growth, motion, function and overall health of the spine. This study represents our first ten years using AVT to treat AIS.

METHODS

In this retrospective review we analyzed our first 74 AIS patients treated with AVT 2010-2020. Multiple Lenke curve types 33-70° were treated with skeletal maturity spanning Risser -1 to 5.

RESULTS

Of 74 consecutive AIS patients treated with AVT, 52 patients (47 female, 5 male) had sufficient 2-year follow-up for inclusion. Forty-six of these 52 patients (88%) with 65 curves (35T, 30TL/L) were satisfactorily treated with AVT demonstrating curve correction from 48.6° pre-op (range 33°-70°) at age 15.1 years (range 9.2-18.8) and skeletal maturity of Risser 2.8 (range -1 to 5) to 23.2° post-op (range 0°-54°) and 24.0° final (range 0°-49°) at 3.3 years follow-up (range 2-10 years). Curve corrections from pre-op to post-op and pre-op to final were both significant (p < 0.001). The 0.8° change from post-op to final was not significant but did represent good control of scoliosis correction over time. Thoracic kyphosis and lumbar lordosis were maintained in a normal range throughout while axial rotation demonstrated a slight trend toward improvement. Skeletal maturity of Risser 4 or greater was achieved in all but one patient. Four of the 52 patients (8%) required additional procedures for tether rupture (3 replacements) or overcorrection (1 removal) to achieve satisfactory treatment status after AVT. An additional 6 of the 52 patients (12%), however, were not satisfactorily treated with AVT, requiring fusion for overcorrection (2) or inadequate correction (4).

CONCLUSIONS

In this study, AIS was satisfactorily treated with AVT in the majority of patients over a broad range of curve magnitudes, curve types, and skeletal maturity. Though late revision surgery for overcorrection, inadequate correction, or tether rupture was not uncommon, the complication of overcorrection was eliminated after our first ten patients by a refinement of indications.

LEVEL OF EVIDENCE

IV.

Biomechanical Comparison of Different Surgical Strategies for Skip-level Cervical Degenerative Disc Disease: A Finite Element Study

STUDY DESIGN

We constructed finite element (FE) models of the cervical spine consisting of C2-C7 and predicted the biomechanical effects of different surgical procedures and instruments on adjacent segments, internal fixation systems, and the overall cervical spine through FE analysis.

OBJECTIVE

To compare the biomechanical effects between the zero-profile device and cage-plate device in skip-level multistage anterior cervical discectomy and fusion (ACDF).

SUMMARY OF BACKGROUND DATA

ACDF is often considered the standard treatment for degenerative cervical spondylosis. However, the selection of surgical methods and instruments in cases of skip-level cervical degenerative disk disease is still controversial.

MATERIALS AND METHODS

Three FE models were constructed, which used noncontiguous 2-level Zero-P (NCZP) devices for C3/4 and C5/6, a noncontiguous 2-level cage-plate (NCCP) for C3/4 and C5/6, and a contiguous 3-level cage-plate (CCP) for C3/6. Simulate daily activities in ABAQUS. The range of motion (ROM), von Mises stress distribution of the endplate and internal fixation system, and intervertebral disk pressure (IDP) of each model were recorded and compared.

RESULTS

Similar to the stress of the cortical bone, the maximum stress of the Zero-P device was higher than that of the CP device for most activities. The ROM increments of the superior, inferior, and intermediate segments of the NCZP model were lower than those of the NCCP and CCP models in many actions. In terms of the IDP, the increment value of stress for the NCZP model was the smallest, whereas those of the NCCP and CCP models were larger. Similarly, the increment value of stress on the endplate also shows the minimum in the NCZP model.

CONCLUSIONS

Noncontiguous ACDF with zero profile can reduce the stress on adjacent intervertebral disks and endplates, resulting in a reduced risk of adjacent segment disease development. However, the high cortical bone stress caused by the Zero-P device may influence the risk of fractures.

The insert and revolve technique: a novel approach for inserting cages during unilateral biportal endoscopic assisted fusion surgery for effective spinal alignment restoration

STUDY DESIGN

Retrospective study.

PURPOSE

This study aimed to propose a method of performing unilateral biportal endoscopy (UBE)-assisted interbody cage insertion for fusion using the "insert and revolve" technique and analyze the clinico-radiological outcomes.

OVERVIEW OF LITERATURE

UBE-assisted lumbar interbody fusion (ULIF) is a rapidly evolving technique combining the advantages of minimally invasive technique with ease of learning. The limited size of cages was a result of the narrow insertion channel. We propose a technique in which large extreme lateral interbody fusion cages can be inserted through the same opening.

METHODS

This study included 104 patients who underwent ULIF using the "insert and revolve technique" between July 2019 and September 2022. The patients were followed up for at least 12 months postoperatively. The clinical outcomes were assessed using the Visual Analog Scale (VAS) for leg pain and back pain, Oswestry Disability Index (ODI), and modified McNab's criteria. Changes in segmental lordosis (SL), intervertebral disc height (IVDH), segmental coronal alignment (SCA), cage subsidence, and fusion grade were evaluated at 6- and 12-month follow-up.

RESULTS

The VAS scores for leg and back pain and ODI score showed significant improvement. Based on the Macnab's criteria, 97 patients showed excellent outcomes and seven demonstrated good outcomes at 12 months. The mean IVDH increased from 6.3±2 to 10±2.1 mm immediately after surgery and 10±1.1 mm at 6 months. SL improved from 9.3°±11.5° to 17.78°±8.1°, while SCA improved from 7.7°±2.1° to 3.4°±1.2° at 1 year. Moreover, 92 and 11 patients showed grade 1 and 2 fusion, respectively, according to the Bridwell grading at 1 year.

CONCLUSIONS

The "insert and revolve technique" facilitates the successful insertion of large cages, contributing to the restoration of disc height and coronal and sagittal spinal correction with favorable fusion rates.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Trends in Indications and Contraindications for Cervical Disk Arthroplasty from 2009 to 2019

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

Assess trends of indications and contraindications for the use of Cervical Disk Arthroplasty (CDA).

SUMMARY OF BACKGROUND DATA

As spine surgeons become more familiar with CDA, there have been expansions in indications.

METHODS

The Medicare Provider Analysis and Review Limited Data Sets for 2009, 2014, and 2019 were utilized. Patients undergoing elective CDA were included. Diagnosis for index surgery and "contraindications" as defined by original CDA Investigative Device Exemption (IDE) criteria were assessed. Variables were identified by the International Classification of Diseases (ICD)-9 or ICD-10 diagnosis and procedural codes.

RESULTS

A total of 1067 elective CDA patients were included. There were 230 patients in 2009, 300 patients in 2014, and 537 patients in 2019. The proportion of patients aged >65 increased from 35% to 51% ( P <0.001). Incidence of CDA for radiculopathy increased from 57% to 69% ( P <0.001), myelopathy increased from 23% to 78% ( P <0.001), and spondylosis without radiculopathy or myelopathy decreased from 19% to 3% ( P <0.001). There were increased incidences of ankylosing spondylitis (0.4% to 2.8%, P =0.007), long-term steroid use (1% to 2%, P =0.039), morbid obesity (2% to 6%, P =0.019), and osteoporosis (1% to 5%, P =0.014). The incidence of hybrid CDA and anterior cervical discectomy and fusion (ACDF) decreased from 28% to 23% ( P =0.007).

CONCLUSION

From 2009 to 2019, the number of CDA performed in older patients increased. An increase in the use of CDA for the treatment of myelopathy and radiculopathy and a decrease in the treatment of isolated cervical spondylosis was observed. The proportion of CDA performed in patients with original IDE trial "contraindications" increased. Further research into the efficacy of CDA for patients with contraindications is warranted.

Comparative effectiveness of cortical bone trajectory screws and pedicle screws in the treatment of adjacent segment degeneration after lumbar fusion surgery: a systematic review and meta-analysis

PURPOSE

To compare the efficacy and safety of cortical bone trajectory (CBT) screw and pedicle screw (PS) internal fixation in the treatment of adjacent segment degeneration (ASD) after lumbar fusion.

METHODS

This study was registered on International Prospective Register of Systematic Reviews (PROSPERO) (ID: CRD42023484937). We searched PubMed, Embase, Web of Science, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wan Fang Database, and Wei Pu Database by computer to collect controlled clinical studies on the efficacy and safety of cortical bone trajectory (CBT) screw and pedicle screw (PS) internal fixation in the treatment of adjacent segment degeneration (ASD) after lumbar fusion from database establishment to November 2023. Two researchers screened the literature, extracted data and evaluated the risk of bias of the included studies, recorded the authors, and sample size, and extracted the intraoperative blood loss, operation time, Oswestry disability index (ODI), Visual analogue scale (VAS), disc height (DH), hospital length stay and complications in each study. Meta-analysis was performed using Revman 5.4 software provided by Cochrane Library.

RESULTS

A total of 6 cohort studies (CS) and 1 randomized controlled study with a total of 420 patients were included in this study, including 188 patients in the CBT group and 232 patients in the PS group. The CBT group had lower intraoperative blood loss than the PS group [mean difference (MD) = -129.38, 95% CI (-177.22, -81.55), P < 0.00001] and operation time was shorter than that of the PS group [MD = -1.42, 95% CI (-2.63, -0.20), P = 0.02]. Early postoperative back and leg pain improved more significantly in the CBT group [MD = -0.77, 95% CI (-1.35, -0.19), P = 0.01; MD = -0.24, 95% CI (-0.37, -0.10), P = 0.0005].

CONCLUSION

Compared with PS, CBT for adjacent segment degeneration after lumbar fusion has the advantages of less intraoperative blood loss, shorter operation time, and less back and leg pain in the early postoperative period.

Cervical Sagittal Alignment and Related Factor Analysis and Prediction Model in Patients Undergoing Revision Surgery After Anterior Cervical Fusion

INTRODUCTION

Patients with myelopathy or radiculopathy commonly undergo anterior cervical fusion surgery (ACFS), which has a notable failure rate on occasion. The goal of this study was to compare revision and nonrevision surgery patients in cervical sagittal alignment (CSA) subsequent to ACFS; additionally, to identify the best CSA parameters for predicting clinical outcome after ACFS; and furthermore, to create an equation model to assist surgeons in making decisions on patients undergoing ACFS.

METHODS

The data of 99 patients with symptomatic cervical myelopathy/radiculopathy who underwent ACFS were analyzed. Patients were divided into group A (underwent revision surgery after the first surgery failed) and group B (underwent only the first surgery). We measured and analyzed both preoperative and postoperative CSA parameters, including C2 slope, T1 slope, cervical lordosis C2-C7 (CL), C2-C7 sagittal vertical axis (C2C7 SVA), occiput-C2 lordosis angle (C0-C2), and chin brow vertical angle, and we further computed the correlation between the CSA parameters and created a prediction model.

RESULTS

The (T1S-CL)-C2S mismatch differed significantly between groups A and B ([9.95 ± 9.95] 0 , [3.79 ± 6.58] 0 , P < 0.05, respectively). A significant correlation was observed between C2 slope and T1CL in group B relative to group A postoperatively (R 2 = 0.42 versus R 2 = 0.09, respectively). Compared with group B, patients in group A had significantly higher C2C7SVA values, more levels of fusion, and more smokers. The sensitivity, specificity, accuracy, and discrimination of the model were, respectively, 73.5%, 84%, 78.8%, and 85.65%.

CONCLUSION

The causes of revision surgery in cervical myelopathic patients after anterior cervical corpectomy and fusion/anterior cervical diskectomy and fusion are multifactorial. (T1S-CL)-C2S mismatch and high C2C7SVA are the best cervical sagittal parameters that increase the odds of revision surgery, and the effect is more enhanced when comorbidities such as smoking, low bone-mineral density, and increased levels of fusion are taken into account.

Could the different surgical goals of fusion and non-fusion also be achieved in combination within the same patient? Clinical and radiological outcome of hybrid cervical spine surgery

PURPOSE

Hybrid cervical spine surgery (HS) is a novel surgical strategy wherein an artificial disc replacement is done with a cervical fusion nearby with a stand-alone titanium cage to combine the advantages in both procedures. The aim of this study was to evaluate interactions of these devices within the same patient, and to analyze, if the different goal of each implant is accomplished.

METHODS

Thirty-six patients were treated surgically within a non-randomized retrospective study framework with HS. Patients were examined preoperatively followed by clinical and radiological examination at least one year postoperative. Clinical outcome was detected with NDI, VAS arm/neck, pain self-assessment questionnaires and subjective patient satisfaction. Radiological assessments included RoM, segmental lordosis, cervical lordosis of C2-C7, subsidence, ap-migration and heterotopic ossifications (HO) at the cTDR levels.

RESULTS

Statistically significant improvement of all clinical scores was observed (NDI 37.5 to 5.76; VASarm 6.41 to 0.69; VASneck 6.78 to 1.48). Adequate RoM was achieved at cTDR levels. RoM in the ACDF levels was reduced statistically significant (p < 0.001), and solid fusion (> 2°) was achieved in all evaluated fusion level. Global lordosis (C2-C7) increased statistically significant (2.4° to 8.1°). Subsidence and HO at the cTDR levels did not occur.

CONCLUSIONS

HS results in preservation of the segmental motion in the cTDR and fast and solid fusion in the cage cohort simultaneously. Patient safety was proven. In carefully selected cases, HS is a safe and viable treatment option by choosing the right "philosophy" level per level.

Structural modification and biomechanical analysis of lumbar disc prosthesis: A finite element study

BACKGROUND

Most ball-in-socket artificial lumbar disc implanted in the spine result in increased hypermobility of the operative level and overloading of the facet joint.

METHODS

A finite element model was established and validated for the lumbar spine (L1-L5). The structure of the Mobidisc prosthesis was modified, resulting in the development of two new intervertebral disc prostheses, Movcore and Mcopro. The prostheses were implanted into the L3/L4 level to simulate total disc replacement, and the biomechanical properties of the lumbar spine model were analyzed after the operation.

FINDINGS

Following the implantation of the prostheses, the mobility of operative level, peak stress of lumbar spine models, and peak stress of facet joint increased. The performance of mobility was found to be more similar between Movcore and Mobidisc. The mobility and facet joint peak stress of the Mcopro model decreased progressively with an increase in the Young's modulus of the artificial annulus during flexion, extension, and lateral bending. Among all the models, the Mcopro50 model had the mobility closest to the intact model. It showed a 3% decrease in flexion, equal range of motion in extension, a 9% increase in left lateral bending, a 7% increase in right lateral bending, and a 3% decrease in axial rotation.

INTERPRETATION

The feasibility of the new intervertebral disc prostheses, Movcore and Mcopro, has been established. The Mcopro prosthesis, which features an artificial annular structure, offers significant advantages in terms of reduced mobility of the operative level and peak stress of facet joint.

Biomechanical Analysis of Trapezoidal Thread Screw-Rod Fixation in Pedicle Section of Cervical Spine: A Finite-Element Analysis

Background

Cervical pedicle screw-rod fixation presents a complex approach in spinal surgery, offering enhanced spine stabilization in variable conditions considering traumatic injuries, degenerative changes, as well as orthopaedic and oncological ailments. This technique employs small diameter screw implants strategically placed to bolster the mechanical integrity of the spine. Notably, it involves minimally invasive procedures, resulting in smaller incisions and reduced patient discomfort. This study aims to assess the effects of trapezoidal thread screws in pedicle sections of the cervical spine during flexion-extension loadings, focusing on factors such as range of motion (ROM), implant stress, and stress on adjacent bone.

Methods

Utilizing CT scan data, a finite element model of the cervical spine (C2-C7 vertebrae) was prepared. Trapezoidal thread screws were integrated into a single-level pedicle screw-rod fixation at the C5-C6 vertebrae. The C2 vertebra were given a compressive load of 50 N along with a moment of 1 Nm, resulting in the immobilization of the C7.

Results and Discussion

The results indicate a reduction in ROM at the C5-C6 level by 69% to 77% compared to the intact spine during flexion-extension loading, with a slight increase in ROM observed at adjacent cervical spine levels. Stress analysis revealed that the trapezoidal thread screws induced stresses ranging from 24 MPa to 29 MPa in PEEK trapezoidal screw-rod implants, which fall below the material's yield stress.

Conclusions

This suggests that the trapezoidal thread profile may be advantageous in minimizing stress concentration, attributed to its larger contact area with the vertebrae bone between the threads.

In vivo study of a novel 3D-printed motion-preservation artificial cervical corpectomy construct: short-term imaging and biocompatibility evaluations in a goat model

BACKGROUND

Nonfusion technologies, such as motion-preservation devices, have begun a new era of treatment options in spine surgery. Motion-preservation approaches mainly include total disc replacement for anterior cervical discectomy and fusion. However, for multisegment fusion, such as anterior cervical corpectomy and fusion, the options are more limited. Therefore, we designed a novel 3D-printed motion-preservation artificial cervical corpectomy construct (ACCC) for multisegment fusion. The aim of this study was to explore the feasibility of ACCC in a goat model.

METHODS

Goats were treated with anterior C3 corpectomy and ACCC implantation and randomly divided into two groups evaluated at 3 or 6 months. Radiography, 3D CT reconstruction and MRI evaluations were performed. Biocompatibility was evaluated using micro-CT and histology.

RESULTS

Postoperatively, all goats were in good condition, with free neck movement. Implant positioning was optimal. The relationship between facet joints was stable. The range of motion of the C2-C4 segments during flexion-extension at 3 and 6 months postoperatively was 7.8° and 7.3°, respectively. The implants were wrapped by new bone tissue, which had grown into the porous structure. Cartilage tissue, ossification centres, new blood vessels, and bone mineralization were observed at the porous metal vertebrae-bone interface and in the metal pores.

CONCLUSIONS

The ACCC provided stabilization while preserving the motion of the functional spinal unit and promoting bone regeneration and vascularization. In this study, the ACCC was used for anterior cervical corpectomy and fusion (ACCF) in a goat model. We hope that this study will propel further research of motion-preservation devices.

Does the extent of soft tissue dissection and location of screws in anterior cervical discectomy and fusion impact the development of the adjacent segment degeneration? A prospective short-term radiological analysis

BACKGROUND

Cervical degenerative disc disease is a common condition in neurosurgical practice. Elimination of a motion segment through fusion causes the load shift to the adjacent levels leading to disc degeneration. Our hypothesis is that by avoiding excessive dissection of the prevertebral soft tissue and placing anchoring screws away the adjacent endplate, we can reduce the load bearing and degeneration rate.

METHODS

This is a prospective randomized control study. The study included 30 consecutive cases requiring single level ACDF, 15 each in conservative and minimal dissection group. MRI evidence of disc degeneration was assessed according to Matsumoto MRI grading system.

RESULTS

No significant role of age on ASD was noted (P=0.26). ASD was worse in females than males especially at the inferior level (P=0.035). ASD was noted to be higher when the patients were operated at C5-6 level (P=0.026). The reduction in VAS was 5.933 in the minimal dissection group which was significantly better than the conventional surgery group (5.14) (P=0.023). The increase in degeneration score was 0.97 and 0.6 at superior and inferior levels, respectively, in the conventional group and 0.13 and 0.34 in minimal dissection group.

CONCLUSIONS

The minimal soft tissue dissection for single level ACDF with PEEK cage placement appears to have reducing rate of ASD compared to conventional ACDF. Minimal soft tissue dissection has better postoperative VAS scores.

Dynamic Cervical Spinal Canal Stenosis: Identifying Imaging Risk Factors in Extended Positions

STUDY DESIGN

A retrospective study at a single academic institution.

PURPOSE

This study aimed to identify imaging risk factors for stenosis in extended neck positions undetectable in preoperative neutral magnetic resonance imaging (MRI) and improving decompression strategies for cervical spine disorders.

OVERVIEW OF LITERATURE

Cervical disorders are influenced by various dynamic factors, with spinal stenosis appearing during neck extension. Despite the diagnostic value of dynamic cervical MRI, standard practice often uses neutral-position MRI, potentially influencing surgical outcomes.

METHODS

This study analyzed 143 patients who underwent decompression surgery between 2012 and 2014, who had symptomatic cervical disorders and MRI evidence of spinal cord or nerve compression but had no history of cervical spine surgery. Patient demographics, disease type, Japanese Orthopedic Association score, and follow-up periods were recorded. Spinal surgeons conducted radiological evaluations to determine stenosis levels using computed tomography myelography or MRI in neutral and extended positions. Measurements such as dural tube and spinal cord diameters, cervical alignment, range of motion, and various angles and distances were also analyzed. The residual space available for the spinal cord (SAC) was also calculated.

RESULTS

During extension, new stenosis frequently appeared caudal to the stenosis site in a neutral position, particularly at C5/C6 and C6/C7. A low SAC was identified as a significant risk factor for the development of new stenosis in both the upper and lower adjacent disc levels. Each 1-mm decrease in SAC resulted in an 8.9- and 2.7-fold increased risk of new stenosis development in the upper and lower adjacent disc levels, respectively. A practical SAC cutoff of 1.0 mm was established as the threshold for new stenosis development.

CONCLUSIONS

The study identified SAC narrowing as the primary risk factor for new stenosis, with a clinically relevant cutoff of 1 mm. This study highlights the importance of local factors in stenosis development, advocating for further research to improve outcomes in patient with cervical spine disorders.

Stand-Alone Anchored Spacer vs Anterior Plate Construct in the Management of Adjacent Segment Disease after Anterior Cervical Discectomy and Fusion: A Systematic Review and Meta-Analysis of Comparative Studies

STUDY DESIGN

Systematic Review and Meta-Analysis.

OBJECTIVES

This study aimed to evaluate the clinical and radiological outcomes of surgically treated adjacent segment disease (ASDis) following ACDF with either anterior plate construct (APC) or stand-alone anchored spacers (SAAS).

METHOD

Multiple databases were searched until December 2022 for pertinent studies. The primary outcome was health-related quality of life outcomes [JOA, NDI, and VAS], whereas, the secondary outcomes included operative characteristics [estimated blood loss (EBL) and operative time (OT)], radiological outcomes [C2-C7 Cobb angle, disc height index (DHI) changes, fusion rate], and complications.

RESULTS

A total of 5 studies were included, comprising 210 patients who had been surgically treated for cervical ASDis. Among them, 113 received APC, and 97 received SAAS. Postoperative dysphagia was significantly higher in the APC group [47% vs 11%, OR = 7.7, 95% CI = 3.1-18.9, P < .05]. Similarly, operative time and blood loss were higher in the APC group compared to the SAAS group; [MD = 16.96, 95% CI = 7.87-26.06, P < .05] and [MD = 5.22, 95% CI = .35 - 10.09, P < .05], respectively. However, there was no difference in the rate of prolonged dysphagia and clinical outcomes in terms of JOA, NDI, and VAS. Furthermore, there was no difference in the radiological parameters including the C2-7 Cobb angle and DHI as well as the fusion rate.

CONCLUSION

Our meta-analysis demonstrated that both surgical techniques (APC and SAAS) are effective in treating ASDis. However, with low certainty of the evidence, considering patients are at high risk of dysphagia following revision cervical spine surgery SAAS may be the preferred choice.

Incidence of Sacroiliac Joint Pain Following Lumbar Fractures: A Retrospective-Cohort Study

BACKGROUND

Sacroiliac joint (SIJ) pain commonly affects patients with low back pain and can arise from traumatic and degenerative causes. However, the incidence of SIJ pain following lumbar fractures is not well understood.

METHODS

TriNetX, a national network of deidentified patient records, was retrospectively queried. The lumbar fracture cohort included 239,199 adults, while the no lumbar fracture group included 6,975,046 adults. Following a propensity-score match based on demographics and risk factors for SIJ, there were 239,197 patients in each cohort. The incidence of SIJ pain and clinical outcomes were analyzed from 1 day to 1 year following the index event. Moreover, the location and type of single-level lumbar fractures were reported. The incidence of SIJ pain for single-level fractures was compared using a χ2 goodness-of-fit.

RESULTS

The lumbar fracture cohort was more likely to develop SIJ pain at 3 months (odds ratio [OR]: 5.3, 95% confidence interval [CI]: 4.8-5.9), 6 months (OR: 4.4, 95% CI: 4.1-4.8), and 1 year (OR: 3.9, 95% CI: 3.6-4.2) postfracture. Among single-level lumbar fractures, the incidence of SIJ pain at 1 month (P = 0.005), 6 months (P = 0.010), and 1 year (P = 0.003) varied significantly, with the highest incidence in the L5 cohort.

CONCLUSIONS

Our findings suggest that lumbar fractures are a risk factor for developing SIJ pain. Moreover, the incidence of SIJ pain is greater following an L5 fracture than an L1 fracture. Further investigation is warranted to determine how the type and treatment of lumbar fractures affects the incidence of SIJ pain.

A Propensity Score-Matched Cohort Study Comparing 3 Different Spine Pedicle Screw Fixation Methods: Freehand, Fluoroscopy-Guided, and Robot-Assisted Techniques

OBJECTIVE

This study aimed to compare the accuracy of robotic spine surgery and conventional pedicle screw fixation in lumbar degenerative disease. We evaluated clinical and radiological outcomes to demonstrate the noninferiority of robotic surgery.

METHODS

This study employed propensity score matching and included 3 groups: robot-assisted mini-open posterior lumbar interbody fusion (PLIF) (robotic surgery, RS), c-arm guided minimally invasive surgery transforaminal lumbar interbody fusion (C-arm guidance, CG), and freehand open PLIF (free of guidance, FG) (54 patients each). The mean follow-up period was 2.2 years. The preoperative spine condition was considered. Accuracy was evaluated using the Gertzbein-Robbins scale (GRS score) and Babu classification (Babu score). Radiological outcomes included adjacent segmental disease (ASD) and mechanical failure. Clinical outcomes were assessed based on the visual analogue scale, Oswestry Disability Index, 36-item Short Form health survey, and clinical ASD rate.

RESULTS

Accuracy was higher in the RS group (p < 0.01) than in other groups. The GRS score was lower in the CG group, whereas the Babu score was lower in the FG group compared with the RS group. No significant differences were observed in radiological and clinical outcomes among the 3 groups. Regression analysis identified preoperative facet degeneration, GRS and Babu scores as significant variables for radiological and clinical ASD. Mechanical failure was influenced by the GRS score and patients' age.

CONCLUSION

This study showed the superior accuracy of robotic spine surgery compared with conventional techniques. When combined with minimally invasive surgery, robotic surgery is advantageous with reduced ligament and muscle damage associated with traditional open procedures.

Impact of prior spinal fusion surgery on complications and functional outcomes following total hip arthroplasty: an updated systematic review and meta-analysis

PURPOSE

This study aimed to compare the complication rates and functional outcomes between patients with and without a history of spinal fusion undergoing THA.

METHODS

A systematic search was conducted across PubMed, EMBASE, Scopus, and Cochrane databases. Studies that compared adults with and without a history of spinal fusion after primary THA were included. The methodological quality of the studies was evaluated using MINORS criteria. Meta-analyses were performed utilizing mean differences (MD), standardized mean differences (SMD), and odds ratios (OR), along with 95% confidence intervals (CI).

RESULTS

Seventeen studies involving 1,789,356 patients (31,786 in the SF group and 1,757,570 in the Non-SF group) were analyzed. The spinal fusion group exhibited significantly higher rates of dislocation (OR 2.50, 95% CI 1.78-3.52), periprosthetic fracture (OR 1.96, 95% CI 1.39-2.77), overall complications (OR 1.73, 95% CI 1.10-2.71), and revision rates (OR 1.86, 95% CI 1.74-1.99). Furthermore, within the first three months, there was an increased risk of dislocation (OR 4.38, 95% CI 1.36-14.14) and revisions (OR 3.87, 95% CI 1.63-9.18). Longer spinal fusions were significantly associated with a higher risk of dislocations (OR 0.62, 95% CI 0.53-0.71). Additionally, prior spinal fusion was linked to higher levels of pain (SMD 0.11, 95% CI 0.02-0.19) and poorer functional outcomes (MD - 0.09, 95% CI - 0.18 to - 0.00).

CONCLUSIONS

Patients with a history of spinal fusion undergoing THA exhibit increased complication rates, higher levels of pain, and greater functional limitations than those without prior fusion. These findings have significant clinical implications for optimizing perioperative care in high-risk patient populations.

Preoperative Adjacent Facet Joint Osteoarthritis Is Associated with the Incidence of Adjacent Segment Degeneration and Low Back Pain after Lumbar Interbody Fusion

STUDY DESIGN

A retrospective cohort study.

PURPOSE

To analyze the association between preoperative adjacent facet joint osteoarthritis (FJOA) and outcomes of lumbar interbody fusion (LIF).

OVERVIEW OF LITERATURE

Whether preoperative adjacent FJOA is associated with the incidence of radiological adjacent segment degeneration (RASD) and low back pain (LBP) relief after lumbar fusion remains unknown.

METHODS

The study included patients who underwent LIF. The demographic characteristics and radiographic and surgical data were collected and evaluated. The included patients were divided into control group and FJOA group based on the preoperative adjacent facet joint Pathria grade. Preoperative and last follow-up LBP Visual Analog Scale (VAS) score, leg pain (LP) VAS, Oswestry Disability Index (ODI) and RASD were evaluated and compared. The improvement rates in VAS and ODI were calculated and compared between the two groups. Logistic regression was used to analyze the risk factors of LBP relief and incidence of RASD.

RESULTS

In total, 197 patients (control group, 86; FJOA group, 111) were included, and the median follow-up was 46 months. The VAS and ODI in both groups significantly improved after surgery. At the last follow-up, the FJOA group had higher VAS and lower VAS improvement rates of LBP than the control group (p<0.05). However, no significant difference in the LP VAS and ODI was found between the two groups. The incidence of RASD in the FJOA group was significantly higher than that in the control group (48.6% vs. 30.2%, p=0.034). Multivariate logistic regression analysis showed that preoperative adjacent FJOA was significantly associated with LBP relief (odds ratio [OR], 0.691; 95% confidence interval [CI], 0.498-0.958) and the postoperative incidence of RASD (OR, 1.406; 95% CI, 1.020-1.939).

CONCLUSIONS

The preoperative FJOA in the adjacent segments was significantly associated with LBP following LIF. Patients with preoperative FJOA were more likely to have RASD following lumbar fusion surgery.

Prospective, multicenter clinical trial comparing the M6-C compressible cervical disc with anterior cervical discectomy and fusion for the treatment of single-level degenerative cervical radiculopathy: 5-year results of an FDA investigational device exemption study

BACKGROUND CONTEXT

Various total disc replacement (TDR) designs have been compared to anterior cervical discectomy and fusion (ACDF) with favorable short and long-term outcomes in FDA-approved investigational device exemption (IDE) trials. The unique design of M6-C, with a compressible viscoelastic nuclear core and an annular structure, has previously demonstrated favorable clinical outcomes through 24 months.

PURPOSE

To evaluate the long-term safety and effectiveness of the M6-C compressible artificial cervical disc and compare to ACDF at 5 years.

STUDY DESIGN

Prospective, multicenter, concurrently and historically controlled, FDA-approved IDE clinical trial.

PATIENT SAMPLE

Subjects with one-level symptomatic degenerative cervical radiculopathy were enrolled and received M6-C (n=160) or ACDF (n=189) treatment as part of the IDE study. Safety outcomes were evaluated at 5 years for all subjects. The primary effectiveness endpoint was available at 5 years for 113 M6-C subjects and 106 ACDF controls.

OUTCOME MEASURES

The primary endpoint of this analysis was composite clinical success (CCS) at 60 months. Secondary endpoints were function and pain (neck disability index, VAS), physical quality of life (SF-36, SF-12), safety, neurologic, and radiographic assessments.

METHODS

Propensity score subclassification was used to control for selection bias and match baseline covariates of the control group to the M6-C subjects. Sixty-month CCS rates were estimated for each treatment group using a generalized linear model controlling for propensity score.

RESULTS

At 5 years postoperatively, the M6-C treatment resulted in 82.3% CCS while the ACDF group showed 67.0% CCS (superiority p=.013). Secondary endpoints indicated that significantly more M6-C subjects achieved VAS neck and arm pain improvements and showed maintained or improved physical functioning on quality-of-life measures compared to baseline assessments. The M6-C group-maintained flexion-extension motion, with significantly greater increases from baseline disc height and disc angle than observed in the control group. The rates of M6-C subsequent surgical interventions (SSI; 3.1%) and definitely device- or procedure-related serious adverse events (SAE failure; 3.1%) were similar to ACDF rates (SSI=5.3%, SAE failure=4.8%; p>.05 for both).

CONCLUSIONS

Subjects treated with the M6-C artificial disc demonstrated superior 5-year achievement of clinical success when compared to ACDF controls. In addition, significantly more subjects in the M6-C group showed improved pain and physical functioning scores than observed in ACDF subjects, with no difference in reoperation rates or safety outcomes.