Cage Subsidence Research Articles

Influence of Cervical Level Fused on Subsidence of Cage and Allograft in Anterior Cervical Discectomy and Fusion.

Retrospective cohort. This study aims to evaluate the relationship between the cervical levels fused and the degree of subsidence following anterior cervical discectomy and fusion (ACDF) procedures. Subsidence following ACDF may worsen clinical outcomes. Previous studies have linked lower cervical levels with higher rates of subsidence, but none have quantified the relative degree of subsidence between levels. Patients who underwent ACDF from 2016 to 2021 at a tertiary medical center were included in this study. Lateral cervical radiographs from the immediate postoperative period and the final follow-ups were used to calculate subsidence. Analysis of variance was used to examine the association between cervical levels fused and subsidence. Multivariable linear regression analysis controlled for age, sex, smoking status, osteopenia/osteoporosis, number of fused levels, cage-to-body ratio, and cage type while examining the relationship between the cervical level fused and subsidence. This study includes 122 patients who underwent 227 levels fused. There were 16 (7.0%) C3-C4 fusions, 55 (24.2%) C4-C5 fusions, 97 (42.7%) C5-C6 fusions, and 59 (26.0%) C6-C7 fusions. There was a significant difference in the degree of anterior subsidence between cervical levels fused (P = 0.013) with a mean subsidence of 1.0mm (SD: 1.6) for C3-C4, 1.1mm (SD: 1.4) for C4-C5, 1.8mm (SD: 1.5) for C5-C6, and 1.8mm (SD: 1.6) for C6-C7 fusions. Relative to C6-C7 fusions, C4-C5 (P = 0.016), and C3-C4 (P = 0.014) fusions were associated with decreased anterior subsidence, whereas C5-C6 (P = 0.756) fusions were found to have similar degrees of anterior subsidence in the multivariable analysis. We found upper cervical levels experienced a smaller degree of anterior subsidence than lower levels, after controlling for demographic and implant characteristics. Surgeons can consider using larger cages at lower cervical levels to minimize these risks.

Comparison of the long-term efficacy of ROI-C and conventional cage-plate in treatment of spinal cord injury without fracture or dislocation: a retrospective study

BackgroundThe self-locking cage (ROI-C, LDR, Troyes, France) has been clinically applied in the treatment of cervical degenerative disc disease (CDDD). However, only a few long-term clinical and radiographic studies have been conducted on the treatment of spinal cord injury without fracture or dislocation (SCIWFD) so far. A comparison between ACDF with either ROI-C or CCP was performed to determine the better treatment for SCIWFD.MethodsA total of 83 patients who underwent ACDF using either ROI-C or CCP were reviewed for radiological and clinical outcomes. The cohort comprised 60 males and 23 females, aged between 32 and 88 years old, with an average age of 58.23 years. All patients exhibited symptoms of nerve injury, including limb numbness, muscle weakness, hypoesthesia or urinary dysfunction. The preoperative ASIA classification of spinal nerve function: 7 cases of grade A, 23 cases of grade B, 34 cases of grade C and 19 cases of grade D were included in the study.ResultsA total of 48 patients underwent ACDF with ROI-C, while 35 patients received a conventional cage-plate. They were studied with a follow-up of 28.63 ± 17.41 months and 29.48 ± 15.43 months respectively. No significant difference was found in blood loss, JOA and ASIA between the two groups. No significant difference was found in cervical lordosis (CL) (P > 0.05). However, statistical difference was found in disc height of fused segment and T1 slope between the two groups (P < 0.05). No statistical difference was in the incidence of cage subsidence (P > 0.05). There was significant difference in the incidence of dysphagia. Both of two groups achieved bony fusion at final follow-up.ConclusionOur study demonstrated that ROI-C has the same efficacy as CCP in improving the cervical stability in treatment of SCIWFD. The migration of cage didn’t occur in ROI-C group at final follow-up, showing steadily fixed in cervical column. Moreover, the ROI-C does have the advantages of good therapeutic effect, mis-invasive, shorter operation time and fewer complications.

Comparison of Vicious Effect of Oral Pantoprazole and Famotidine on New Bone Formation in Patients With Lumbar Spine Fusion Surgery: A Randomized Control Trial

Background and Aim: Due to the increasing use of proton pump inhibitors (PPIs) and their side effects for bone repair and the high percentage of therapy failure in lumbar fusion surgery, especially in various animal studies, the goal of this study was to appraise the consequence of pantoprazole and famotidine on new bone formation in patients experiencing spinal fusion surgery. Methods and Materials/Patients: In this double-blind clinical trial, eighty patients participated based on the inclusion and exclusion criteria, of whom 40 cases received pantoprazole (group P) and 40 received famotidine (group F) for eight weeks. They were followed up for three, six, and twelve months after surgery for cage subsidence, screw loosening, and visual analogue scale (VAS), Oswestry disability index (ODI), Brantigan, Steffee, Fraser (BSF), and Lenke classification for grading their bone formation. A P&lt;0.05 was considered significant. Results: The rate of fusion based on the Lenke score was lower in the group receiving pantoprazole six and 12 months after the surgery compared to group F (the frequency of Lenke grades C and D were 35% and 25% compared to the famotidine group 12.5% and 12.5%, respectively; P=0.042). The VAS Mean±SD score in group F was lower than group P after 12 months (2.48±1.06 and 1.83±0.55, respectively; P=0.008). There was no pharmacologically significant association between subsidence (P=0.43), loosening (P=0.13), ODI (P=0.31), and BSF (P=0.77) 3, 6 and 12 months post-operation. Conclusion: Affording to the preliminary conclusions of this study, the use of pump inhibitors, such as pantoprazole is more destructive for the ossification process in candidates for spinal fusion requiring the chronic use of drugs for controlling their gastric acid secretion, and H2-blocking drugs, such as famotidine are preferable in this situation after further investigations.

Comparison of Hounsfield Unit, Vertebral Bone Quality, and Dual-Energy X-Ray Absorptiometry T-Score for Predicting Cage Subsidence After Posterior Lumbar Interbody Fusion.

Retrospective cohort study. To compare Hounsfield unit (HU), vertebral bone quality (VBQ), and dual-energy X-ray absorptiometry (DEXA) T-score in predicting cage subsidence (CS) after posterior lumbar interbody fusion. We retrospectively reviewed patients undergoing PLIF and measured L4 HU and VBQ. Baseline characteristics between CS and non-CS groups were compared. Multiple logistic regression analysis was used to identify risk factors for CS. Receiver operating characteristic (ROC) curves were used to explore the predictive value of variables for CS. Subgroup analysis was conducted for patients with available DEXA results. Eighty-four patients were analyzed. The subsidence group was older, with lower L4 HU (92.6 (35.4) vs 130.8 (47.8), P < 0.001) and higher VBQ (3.30 (0.64) vs 2.99 (0.63), P = 0.041) compared to the non-CS group. Low L4 HU (OR 0.979, P = 0.022) was an independent risk factor for subsidence, while VBQ was not. ROC analysis indicated that L4 HU (AUC = 0.733, P < 0.001) exhibited superior predictive performance compared to VBQ (AUC = 0.643, P = 0.032). Subgroup analysis in patients with DEXA showed that the femoral neck T-score (AUC = 0.67, P = 0.037) could differentiate CS, with L4 HU exhibiting the highest predictive ability (AUC = 0.778, P < 0.001), both outperforming VBQ (AUC = 0.645, P = 0.075). Among the three BMD parameters, only low L4 HU could be an independent risk factor for CS. Preoperative HU is mandatory in patients at risk for osteoporosis when undergoing spine surgery.

Finite element analysis of biomechanical investigation on diverse internal fixation techniques in oblique lumbar interbody fusion

BackgroundTo establish a three-dimensional finite element model of the lumbar spine and investigate the impact of different fixation techniques on the biomechanical characteristics of oblique lumbar interbody fusion (OLIF).MethodsThe study aimed to establish and validate a comprehensive three-dimensional model of the lower lumbar spine (L3-S1) using the finite element method. L4-L5 was selected as the surgical segment, and four distinct OLIF surgical models were constructed: Stand-alone (SA), unilateral cortical bone trajectory screw (UCBT), bilateral cortical bone trajectory screw (BCBT), and bilateral pedicle screw (BPS). The models were underwent a pure moment of 10N·m to simulate lumbar extension, flexion, left bending, right bending, left and right rotation movements. Subsequently, the range of motion (ROM), cage stress, and fixation stress were calculated.ResultsIn the L3-L5 segment, the BCBT group showed the most limited range of motion (ROM) under exercise load, indicating superior stability within this group. The ROM and cage stress values were found to be highest in the SA group. In contrast, the cage and internal fixation stress in the BPS group were observed to be lowest (9.91 ~ 53.83MPa, 44.93 ~ 84.85 MPa). With the exception of right bending and right rotation, the UCBT group demonstrated higher levels of internal fixation stress (102.20 ~ 164.62 MPa).ConclusionsThe study found that OLIF-assisted internal fixation improved segmental stability and reduced cage stress. The BPS group had advantages over the CBT group in preventing endplate damage and reducing the risk of cage subsidence. However, BCBT group has distinct merits in maintaining surgical segment stability, distributing stress load on the spinal motor unit, and reducing the likelihood of adjacent segment degeneration (ASD).

MRI-based endplate bone quality score independently predicts cage subsidence after anterior cervical corpectomy fusion.

To reduce the amount of radiation that patients receive during surgery, surgeons can evaluate the quality of the bone prior to surgery using computed tomography (CT) or dual-energy X-ray absorptiometry. Recently, lumbar spine vertebral bone quality has been evaluated using an MRI-based scoring system. However, few studies have investigated the connection between cage subsidence in patients following cervical interbody fusion and site-specific MRI bone evaluation. It is unknown how cage subsidence following anterior cervical corpectomy decompression and fusion is related to MRI-based endplate bone quality assessment. To create a similar MRI-based cervical spine scoring system (C-EBQ) and to investigate the predictive value of the MRI cervical endplate bone quality (C-EBQ) score for cage subsidence after ACCF. The patients' demographic, surgical, and radiological data were collected. Cage subsidence was defined as fusion segment height loss ≥ 3mm. Multivariate logistic regression models were developed to determine correlations between potential risk factors and subsidence, and simple linear regression analyses of statistically significant indicators were performed. Among the patients who underwent single-level ACCF, 72 met the requirements for inclusion. The C-VBQ scores also improved from 2.28 ± 0.12, indicating no subsidence, to 3.27 ± 0.35, which indicated subsidence, and the C-EBQ scores improved in both the nonsubsidence group (1.95 ± 0.80) and the subsidence group (2.38 ± 0.54). There was a statistically significant difference (p < 0.05) among the groups. Higher C-EBQ scores were strongly correlated with subsidence in the multivariate analysis (odds ratio [OR] = 17.249, 95% CI = 2.269 to 7.537, P < 0.001), and the C-VBQ score was the major independent predictor of subsidence following ACCF ([OR] = 4.752, 95% CI = 3.824 to 8.781, P < 0.05). The C-EBQ score outperformed the C-VBQ score (75.6%) in terms of predictive accuracy, with a ROC curve indicating an 89.4% score. After ACCF, cage subsidence was strongly correlated with higher C-EBQ scores on preoperative MRI. Assessing C-EBQ before ACCF may be a useful way to estimate the likelihood of postoperative subsidence.

The Role of Cage Placement Angle in Optimizing Short-Term Clinical Outcomes in Lateral Lumbar Interbody Fusion

OBJECTIVEThe purpose is to investigate the impact of cage angle on clinical outcomes and indirect decompression efficacy in patients undergoing lateral lumbar interbody fusion (LLIF). METHODSA retrospective review was conducted on 87 patients with single-level lumbar degenerative disease (LDD) who underwent LLIF. Patients were grouped based on the angle of cage placement: minimal (0°-5°), mild (>5° ≤ 15°), and severe (>15°). Clinical outcomes assessed included pain intensity, functional improvement, and complication rates. Magnetic resonance imaging (MRI) evaluations included measurements of canal diameter (CD) and central canal area (CCA) pre- and postoperatively. Patient-reported outcomes were also analyzed using the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ). RESULTSClinical and radiographic outcomes were significantly improved across all cage angle groups. Reductions in low back pain, leg pain, and numbness were significant in all groups, with no significant differences. MRI evaluations revealed significant increases in CD and CCA postoperatively, confirming effective indirect decompression. JOABPEQ scores showed significant improvements in all domains, including low back pain, lumbar function, walking ability, social life function, and mental health. However, the severe angle group had higher rates of delayed cage subsidence (DCS). Complications such as transient motor weakness, thigh pain, numbness, and the need for revision surgery were consistent across groups, with no significant differences. CONCLUSIONSLLIF effectively treats LDD patients, providing significant short-term clinical and radiographic improvements regardless of cage angle. However, oblique cage placement increases the risk of cage subsidence, requiring careful surgical planning and postoperative following.

Magnetic Resonance Imaging-Based Vertebral Bone Quality Score for Prediction of Cage Subsidence and Screw Loosening in Patients Undergoing Degenerative Lumbar Surgery: A Meta-analysis.

Poor bone quality is a risk factor for postoperative complications after degenerative lumbar fusion surgery. The magnetic resonance imaging-based vertebral bone quality (VBQ) score is a good tool for assessing bone quality, and this is the first meta-analysis performed to summarize the predictive value of the VBQ score for cage subsidence and screw loosening in patients undergoing degenerative lumbar surgery. Studies were comprehensively searched in electronic databases. The quality of the studies was assessed. The pooled sensitivity, specificity and summary receiver operating characteristic curve were calculated. Publication bias was assessed and meta-regression was conducted. We ultimately included 9 studies with a total of 1,404 patients with a mean age of 60.4 years and a percentage of females of 57.0%. According to the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies 2) tool to assess methodological quality, the quality of the included studies was relatively low and risks of bias might exist. Results showed that a high VBQ was significantly associated with cage subsidence and screw loosening, and risk factor analysis revealed that the merged odds ratio was 5.37 for cage subsidence and 3.87 for screw loosening. With a VBQ cutoff value of 3.34±0.45, the pooled sensitivity and specificity for the diagnosis of postoperative complications were 0.75 and 0.75, respectively, and the area under the curve was 0.82 (95% confidence interval, 0.78-0.85). A high VBQ was associated with a high risk of cage subsidence and screw loosening in patients who underwent degenerative lumbar surgery. The VBQ score could be considered for identifying high-risk patients for further evaluation.

Effect of Cage Material and Size on Fusion Rate and Subsidence Following Biportal Endoscopic Transforaminal Lumbar Interbody Fusion.

Biportal endoscopic transforaminal lumbar interbody fusion (BE-TLIF) is an emerging, minimally invasive technique performed under biportal endoscopic guidance. However, concerns regarding cage subsidence and sufficient fusion during BE-TLIF necessitate careful selection of an appropriate interbody cage to improve surgical outcomes. This study compared the fusion rate, subsidence, and other radiographic parameters according to the material and size of the cages used in BE-TLIF. In this retrospective cohort study, patients who underwent single-segment BE-TLIF between April 2019 and February 2023 were divided into 3 groups: group A, regular-sized three-dimensionally (3D)-printed titanium cages; group B, regular-sized polyetheretherketone cages; and group C, large-sized 3D-printed titanium cages. Radiographic parameters, including lumbar lordosis, segmental lordosis, anterior and posterior disc heights, disc angle, and foraminal height, were measured before and after surgery. The fusion rate and severity of cage subsidence were compared between the groups. No significant differences were noted in the demographic data or radiographic parameters between the groups. The fusion rate on 1-year postoperative computed tomography was comparable between the groups. The cage subsidence rate was significantly lower in group C than in group A (41.9% vs. 16.7%, p=0.044). The severity of cage subsidence was significantly lower in group C (0.93±0.83) than in groups A (2.20±1.84, p=0.004) and B (1.79±1.47, p=0.048). Cage materials did not affect the 1-year postoperative outcomes of BE-TLIF; however, subsidence was markedly reduced in large cages. Larger cages may provide more stable postoperative segments.

Minimally-invasive trans-facet lumbar interbody fusion using a dual-dimension expandable cage: preliminary results of a multi-institutional retrospective study.

Minimally-invasive trans-facet lumbar interbody fusion (LIF) is an emerging technique that offers the advantages of being safe, enabling decompression, and facilitating patient recovery. An innovative cage that expands in two dimensions has been introduced to restore segmental lordosis and disc height while minimizing the risk of cage subsidence. This study aimed to report our surgical technique of trans-facet LIF utilizing the innovative cag and to report the early clinical outcomes. We retrospectively reviewed the medical records and radiographs of patients who underwent trans-facet LIF with dual-dimension expandable cages from two institutions: Duke University Hospital and Vail-Summit Orthopaedics and Neurosurgery. The analysis covered patient demographics, Oswestry Disability Index (ODI), visual analogue scale (VAS) for back pain, surgical data, complications, and radiographic parameters. Clinical outcomes were compared between pre- and one year post-operation, while radiographic outcomes were compared between pre- and three months post-operation. Twenty patients with a mean age of 61.2 years were included. Seventeen patients (85.0%) had spondylolisthesis, and L4/5 (68.2%) was the most common pathology level. Twelve patients (60.0%) underwent awake surgery, and the mean operative time was 164.5±36.1 minutes, with an estimated blood loss of 64.0±39.5 mL and a hospital stay of 1.75±1.2 days. Four patients (20.0%) experienced cage subsidence; however, none required additional surgery. The VAS score significantly improved from a preoperative average of 7.3±2.7 to 2.6±1.6 one year post-operation (P=0.02). The ODI score also showed a significant decrease, from 48.7±22.9 preoperatively to 16.4±11.1 one year postoperatively (P=0.03). Notably, 80% and 83.3% of patients achieved the minimum clinically important difference in VAS and ODI scores, respectively. The degree of spondylolisthesis was significantly reduced from a median of 5.9 mm preoperatively to 0 mm postoperatively (P<0.001). Additionally, both anterior and posterior disc heights significantly increased after surgery, from 9.8±4.7 to 15.1±2.6 mm (anterior) and from 4.9±3.3 to 10.5±2.2 mm (posterior) (P<0.001 for both). The mean segmental lordosis increased by 2.9 degrees and was associated with cage height (P=0.03), while spinopelvic parameters remained unchanged. Minimally-invasive trans-facet LIF with dual-dimension expandable cages demonstrates a substantial capacity for spondylolisthesis reduction and disc height restoration, and provides good short-term clinical outcomes. It may be the most appropriate method for deploying this large cage as it allows for a large, unobstructed pathway to the disc. However, future studies are needed to determine the long-term outcomes, including the arthrodesis rate.

The Utility of Magnetic Resonance Imaging-based Vertebral Bone Quality Scores as a Predictor of Cage Subsidence Following Transforaminal and Posterior Lumbar Interbody Fusion.

Retrospective study. The objectives were to determine whether vertebral bone quality (VBQ) scores are associated with interbody cage subsidence following transforaminal (TLIF) and posterior (PLIF) lumbar interbody fusions and whether there is a clinically sensitive threshold for subsidence. Interbody cage subsidence following lumbar fusion is a complication that can generate poor surgical outcomes. Prior research has correlated cage subsidence with bone mineral density. VBQ scores derived from magnetic resonance imaging (MRI) have been proposed as a tool for measuring bone mineral density, offering a potential new and convenient preoperative risk assessment tool for subsidence. The study involved patients undergoing single-level PLIF or TLIF between 2007 and 2022. Exclusions were for nondegenerative diagnoses, multilevel/revision surgeries, inadequate radiographs, missing immediate postoperative radiographs, and preoperative MRI studies older than 1 year. VBQ was calculated at L1-L4 from preoperative T1-weighted MRI images. Subsidence was assessed by changes in disc height (DH; >2mm difference) and segmental lordosis (SL; >5 degrees difference) between immediate weight-bearing postoperative and latest postoperative lateral radiographs. Statistical analysis included descriptive and inferential statistics. Subsidence was observed in 27% (SL parameter) and 47% (DH parameter) of 51 total patients. VBQ scores were significantly associated with cage subsidence based on both SL (odds ratio = 7.750, P = 0.012; correlation coefficient = 0.382, P = 0.006) and DH (odds ratio = 4.074, P = 0.026; correlation coefficient = 0.258, P = 0.057) in the combined TLIF/PLIF cohorts. In the cohort of 36 patients undergoing TLIF, a VBQ of 2.70 yielded 100.0% sensitivity and 46.2% specificity in detecting subsidence with SL measurement (area under the curve = 0.812, P < 0.001) and 86.7% sensitivity and 47.6% specificity with the DH measurement (area under the curve = 0.692, P = 0.033). We found that MRI-based VBQ scores are effective predictors of cage subsidence following TLIF surgery. A VBQ score of 2.70 demonstrated a reliable model and high sensitivity for doing so, identifying a potential clinical threshold for preoperative subsidence risk assessment. Level III.

Role of unilateral partial facet joint preservation in postero-lateral approach lumbar interbody fusion for patients with degenerative lumbar spinal stenosis presenting bilateral lower limb symptoms: a retrospective study

BackgroundPosterolateral decompression and fusion with internal fixation is a commonly used surgical approach for treating degenerative lumbar spinal stenosis (DLSS). This study aims to evaluate the impact of preserving a portion of the unilateral facet joint during decompression on surgical outcomes and long-term recovery in patients.MethodsThis study analyzed 73 patients with DLSS accompanied by bilateral lower limb neurological symptoms who underwent single-level L4/5 posterolateral decompression and fusion surgery from January 2022 to March 2023. Patients were categorized into two groups based on the type of surgery received: Group A comprised 31 patients who underwent neural decompression without facet joint preservation, while Group B consisted of 42 patients who underwent neural decompression with preservation of partial facet joints on one side. Regular follow-up evaluations were conducted, including clinical and radiological assessments immediately postoperatively, and at 3 and 12 months thereafter. Key patient information was documented through retrospective chart reviews.ResultsMost patients in both groups experienced favorable surgical outcomes. However, four cases encountered complications. Notably, during follow-up, Group B demonstrated superior 1-year postoperative interbody fusion outcomes (P < 0.05), along with a trend towards less interbody cage subsidence and slower postoperative intervertebral disc height loss. Additionally, Group B showed significantly reduced postoperative hospital stay (P < 0.05).ConclusionUnder strict adherence to surgical indications, the posterior lateral lumbar fusion surgery, which preserves partial facet joint unilaterally during neural decompression, can offer greater benefits to patients.

Cervical Vertebra Bone Quality Score Predicts Zero-Profile Anchored Spacer Interbody Fusion Cage Subsidence after Anterior Cervical Diskectomy and Fusion: A Retrospective Study.

Retrospective study. This retrospective study primary focus is to investigate the relationship between the C-VBQ score and the occurrence of postoperative zero-profile anchored spacer (ROI-C) interbody fusion cage subsidence. Additionally, we aim to evaluate the predictive efficacy of the C-VBQ scoring system for subsidence in the context of ACDF with the ROI-C. Patients who underwent ACDF with the ROI-C cage at our hospital between January 2016 and December 2022 were included in this study. Univariate analysis and multivariate logistic regression were employed to identify independent risk factors associated with ROI-C cage subsidence after ACDF. Pearson correlation analysis was utilized to assess the correlation between the C-VBQ score and the height of ROI-C cage subsidence. A total of 102 patients underwent ACDF with ROI-C in our hospital were included in this study. Univariate analysis showed that age (P = 0.021) and C-VBQ score (P < 0.001) were the influencing factors of cage subsidence. Pearson correlation analysis showed that there was a significant positive correlation between the subsidence height of ROI-C cage and C-VBQ (r = 0.55, P < 0.01). Multivariate binary logistic regression analysis showed that C-VBQ score was the only variable that could significantly predict the subsidence of ROI-C cage after ACDF. Higher C-VBQ score was significantly associated with cage subsidence (P < 0.001).The AUC was 0.89, and the cutoff value for C-VBQ was 2.70. The findings indicate a significant correlation between a higher C-VBQ score before surgery and ROI-C cage subsidence after ACDF. The preoperative assessment of C-VBQ proves valuable for clinicians, enabling them to identify patients with low bone mineral density and predict the risk of zero-profile anchored spacer interbody fusion cage subsidence following ACDF.

Tomographic Assessment of Fusion Rate, Implant-Endplate Contact Area, Subsidence, and Alignment With Lumbar Personalized Interbody Implants at 1-Year Follow-Up.

Incongruity between irregularly shaped vertebral endplates and the uniform surfaces of stock interbody fusion cages has been identified as contributing to cage subsidence, pseudarthrosis, and unpredictable alignment. Advances in manufacturing techniques have driven the development of personalized interbody cages (PICs) that can match individual endplate morphology and provide the exact shape and size needed to fill the disc space and achieve the planned correction. This study used computed tomography (CT) imaging to evaluate the implant-endplate contact area, fusion, subsidence, and achievement of planned alignment correction in patients receiving PIC devices. This retrospective study included patients treated for adult spinal deformity at a single site and implanted with PIC devices at L4 to L5 or L5 to S1 for segmental stabilization and alignment correction, who received 1-year postoperative CT images as part of their standard of care. An evaluation using 3-dimensional thin-section scans was conducted. Implant-endplate contact and signs of fusion were assessed in each CT slice across both endplates. The degree of subsidence as well as measures of segmental and global lumbar alignment were also assessed. Fifteen patients were included in the study, with a mean age of 68.2 years. Follow-up ranged between 9 and 14 months. Twenty-six total lumbar levels were implanted; 20 with PIC devices via the anterior lumbar interbody fusion approach, 2 with stock cages via the anterior lumbar interbody fusion approach, and 4 with PIC devices via the transforaminal lumbar interbody fusion approach. CT analysis of PIC-implanted levels found an overall implant-endplate contact area ratio of 93.9%, a subsidence rate of 4.5%, a fusion rate of 100%, and satisfactory segmental and global lumbar correction compared with the preoperative plan. PIC implants can provide nearly complete contact with endplate surfaces regardless of the individual endplate morphology. Subsidence, fusion, and alignment assessments in this tomographic study illustrated results consistent with the benefits of a personalized interbody implant.

A novel cervical vertebral bone quality score can independently predict cage subsidence after anterior cervical corpectomy and fusion

ObjectivesTo optimize cervical vertebral bone quality (C-VBQ) score and explore its effectiveness in predicting cage subsidence in Anterior Cervical Corpectomy and Fusion (ACCF) and identify a new method for evaluating subsidence without different equipment and image scale interference.MethodsCollecting demographic, imaging, and surgical related information. Measuring Cage Subsidence with a new method. Multifactorial logistic regression was used to identify risk factors associated with subsidence. Pearson’s correlation was used to determine the relationship between C-VBQ and computed tomography (CT) Hounsfield units (HU). The receiver operating characteristic (ROC) curve was used to assess C-VBQ predictive ability. Correlations between demographics and C-VBQ scores were analyzed using linear regression models.Results92 patients were included in this study, 36 (39.1%) showed subsidence with a C-VBQ value of 2.05 ± 0.45, in the no-subsidence group C-VBQ Value was 3.25 ± 0.76. The multifactorial logistic regression showed that C-VBQ is an independent predictor of cage subsidence with a predictive accuracy of 93.4%. Pearson’s correlation analysis showed a negative correlation between C-VBQ and HU values. Linear regression analysis showed a positive correlation between C-VBQ and cage subsidence. Univariate analyses showed that only age was associated with C-VBQ.ConclusionsThe C-VBQ values obtained using the new measurements independently predicted postoperative cage subsidence after ACCF and showed a negative correlation with HU values. By adding the measurement of non-operated vertebral heights as a control standard, the results of cage subsidence measured by the ratio method are likely to be more robust, perhaps can exclude unavoidable errors caused by different equipment and proportional.

Reasons and strategies of reoperation after oblique lateral interbody fusion

To summarize the reasons and management strategies of reoperation after oblique lateral interbody fusion (OLIF), and put forward preventive measures. From October 2015 to December 2019, 23 patients who underwent reoperation after OLIF in four spine surgery centers were retrospectively analyzed. There were 9 males and 14 females with an average age of (61.89±8.80) years old ranging from 44 to 81 years old. The index diagnosis was degenerative lumbar intervertebral dics diseases in 3 cases, discogenic low back pain in 1 case, degenerative lumbar spondylolisthesis in 6 cases, lumbar spinal stenosis in 9 cases and degenerative lumbar spinal kyphoscoliosis in 4 cases. Sixteen patients were primarily treated with Stand-alone OLIF procedures and 7 cases were primarily treated with OLIF combined with posterior pedicle screw fixation. There were 17 cases of single fusion segment, 2 of 2 fusion segments, 4 of 3 fusion segments. All the cases underwent reoperation within 3 months after the initial surgery. The strategies of reoperation included supplementary posterior pedicle screw instrumentation in 16 cases;posterior laminectomy, cage adjustment and neurolysis in 2 cases, arthroplasty and neurolysis under endoscope in 1 case, posterior laminectomy and neurolysis in 1 case, pedicle screw adjustment in 1 case, exploration and decompression under percutaneous endoscopic in 1 case, interbody fusion cage and pedicle screw revision in 1 case. Visual analogue scale (VAS) and Oswestry disability index (ODI) index were used to evaluate and compare the recovery of low back pain and lumbar function before reoperation and at the last follow-up. During the follow-up process, the phenomenon of fusion cage settlement or re-displacement, as well as the condition of intervertebral fusion, were observed. The changes in intervertebral space height before the first operation, after the first operation, before the second operation, 3 to 5 days after the second operation, 6 months after the second operation, and at the latest follow-up were measured and compared. There was no skin necrosis and infection. All patients were followed up from 12 to 48 months with an average of (28.1±7.3) months. Nerve root injury symptoms were relieved within 3 to 6 months. No cage transverse shifting and no dislodgement, loosening or breakage of the instrumentation was observed in any patient during the follow-up period. Though the intervertebral disc height was obviously increased at the first postoperative, there was a rapid loss in the early stage, and still partially lost after reoperation. The VAS for back pain recovered from (6.20±1.69) points preoperatively to (1.60±0.71) points postoperatively(P<0.05). The ODI recovered from (40.60±7.01)% preoperatively to (9.14±2.66)% postoperatively(P<0.05). There is a risk of reoperation due to failure after OLIF surgery. The reasons for reoperation include preoperative bone loss or osteoporosis the initial surgery was performed by Stand-alone, intraoperative endplate injury, significant subsidence of the fusion cage after surgery, postoperative fusion cage displacement, nerve damage, etc. As long as it is discovered in a timely manner and handled properly, further surgery after OLIF surgery can achieve better clinical results, but prevention still needs to be strengthened.

Anatomically and mechanically conforming patient-specific spinal fusion cages designed by full-scale topology optimization

Cage subsidence after instrumented lumbar spinal fusion surgery remains a significant cause of treatment failure, specifically for posterior or transforaminal lumbar interbody fusion. Recent advancements in computational techniques and additive manufacturing, have enabled the development of patient-specific implants and implant optimization to specific functional targets. This study aimed to introduce a novel full-scale topology optimization formulation that takes the structural response of the adjacent bone structures into account in the optimization process. The formulation includes maximum and minimum principal strain constraints that lower strain concentrations in the adjacent vertebrae. This optimization approach resulted in anatomically and mechanically conforming spinal fusion cages. Subsidence risk was quantified in a commercial finite element solver for off-the-shelf, anatomically conforming and the optimized cages, in two representative patients. We demonstrated that the anatomically and mechanically conforming cages reduced subsidence risk by 91% compared to an off-the-shelf implant with the same footprint for a patient with normal bone quality and 54% for a patient with osteopenia. Prototypes of the optimized cage were additively manufactured and mechanically tested to evaluate the manufacturability and integrity of the design and to validate the finite element model.

A novel technique for posterior lumbar interbody fusion to obtain a good local lordosis angle: anterior-release posterior lumbar interbody fusion.

Herein, we describe a novel posterior lumbar interbody fusion (PLIF) technique with annulus fibrosus (AF) release and the use of expandable cages (called "anterior-release PLIF" [ARPLIF]). In this technique, posterior column osteotomy (PCO) and AF release provide excellent intervertebral mobility. AF release involves circumferentially peeling off the AF above or below the endplate between the fixed vertebrae under radiographic guidance without cutting the AF and anterior longitudinal ligament. Subsequently, high-angle variable-angle expandable cages are used to simultaneously expand both sides before inserting the percutaneous pedicle screws and correcting to achieve good local lumbar lordosis. PCO and AF release achieve excellent intervertebral mobility. Intervertebral mobility and simultaneous expansion of both cages disperse the force on the endplates, reducing cage subsidence, and the high-angle cages facilitate high intervertebral angle creation. The novel ARPLIF intervertebral manipulation technique can promote good local lumbar lordosis formation.

Placement of 2 cages using navigation-guided biportal endoscopic transforaminal lumbar interbody fusion: illustrative case.

In recent developments, full endoscopic and unilateral biportal endoscopic (UBE) spine surgery have emerged to aid the transforaminal lumbar interbody fusion (TLIF) procedure. Yet, both approaches present a challenge due to limited space for cage insertion, potentially leading to complications such as cage subsidence or nonfusion in long-term assessments. Utilizing double cages may mitigate these concerns. This paper presents a unique case in which a patient successfully underwent computed tomography (CT) navigation-guided UBE-TLIF with 2 converging cages, highlighting the potential benefits and feasibility of this innovative approach. A 59-year-old female diagnosed with degenerative spondylolisthesis at the L4-5 level underwent a UBE-TLIF. The operation is detailed step by step and supported by illustrative figures and surgical videos. Postsurgery results revealed a significant improvement in the patient's condition, with the visual analog scale score decreasing from 7 to 3 on the first day, leading to a satisfaction rate of 90% at the last follow-up. Utilizing endoscopic visualization complemented by contrast medium has substantially elevated the quality of disc preparation. From their observations, the authors affirm that the integration of intraoperative CT navigation systems significantly augments safety and pinpoint accuracy in UBE-TLIF procedures. The strategy of employing 2 converging cages through a unilateral technique stands as a practical solution, potentially optimizing the fusion outcomes of UBE-TLIF surgery. https://thejns.org/doi/10.3171/CASE23512.

38. MRI-based endplate bone quality score as a predictor of cage subsidence following oblique lumbar interbody fusion

38. MRI-based endplate bone quality score as a predictor of cage subsidence following oblique lumbar interbody fusion