Interbody Fusion Cages Research Articles

Improved clinical and radiographic outcomes with expandable cages in transforaminal lumbar interbody fusion: a propensity-matched cohort analysis.

The restoration of sufficient overall lumbar lordosis (LL) and segmental LL (SL) is associated with achieving optimal sagittal balance, decreasing back pain, and enhancing functional outcomes for patients. Expandable cages were developed in hopes of improving radiographic parameters and clinical outcomes, although current clinical evidence is inconclusive. Here, the authors aimed to evaluate the clinical and radiographic outcomes in patients undergoing one- or two-level open transforaminal lumbar interbody fusion (TLIF) with expandable versus static cage placement, using propensity-matched cohorts. An institutional retrospective cohort of patients who underwent one- or two-level open TLIF with either expandable cage or static cage placement was identified. Using relevant preoperative covariates, including age, primary versus revision operation, number of cages implanted, and surgical level implanted, the authors built propensity-matched cohorts. They identified clinical outcomes in both cohorts, including operative characteristics and complication rates, along with pain, weakness, and sensory deficits over follow-up. Furthermore, they extracted and examined preoperative, postoperative, and last follow-up radiographic parameters. A total of 148 patients were included, and they were followed for a mean of 1.7 years (range 0.5-4.3 years). Propensity matching was used to create cohorts of patients who were similar with respect to age, surgical indication, revision status, number of cages implanted, surgical level implanted, and length of follow-up. Patients in both groups had similar preoperative radiographic parameters. Patients with expandable cages saw larger increases in SL, both postoperatively (5.3° ± 7.5° vs 1.6° ± 5.6°, p = 0.006) and at last follow-up (5.7° ± 7.4° vs 1.0° ± 6.1°, p = 0.003). They also saw significant improvements in pelvic incidence minus LL mismatch at last follow-up (-4.4° ± 13.2° vs 5.8° ± 13.8°, p = 0.009). No differences in intraoperative or perioperative complications were found, but patients with expandable cages were less likely to require readmission, develop adjacent-segment disease, or require revision surgery. They were also more likely to be symptom free at 1 month after surgery and at last follow-up. Expandable cages lead to better restoration of radiographic features, including SL and improvements in clinical outcomes, compared with static cages in propensity-matched cohorts in patients undergoing one- or two-level open TLIFs.

Biportal Endoscopic Transforaminal Lumbar Interbody Fusion: The Double-Cage Technique

Biportal endoscopic transforaminal lumbar interbody fusion (BETLIF) is a novel spinal fusion procedure using the unilateral biportal endoscopic technique. The hydrostatic pressure of saline irrigation suppresses bleeding, enabling us to perform delicate surgery in a crystal-clear and magnified surgical field with almost no bleeding. Adequate neural decompression, disc space preparation, and bony endplate preservation can be achieved safely. The sturdy endplate reduces the incidence of cage subsidence and provides good initial stability. We use 2 interbody fusion cages and a large amount of bone graft to promote fusion. Reduction of the spondylolisthesis can also be achieved using a modern pedicle screw system. This article presents a step-by-step demonstration of the BETLIF technique in a 68-year-old patient with degenerative scoliosis and spondylolisthesis at L4-5, including his clinical presentation and treatment results. BETLIF is a safe, effective, and revolutionary minimally invasive solution for spinal fusion. Its advantages include a magnificent surgical field, direct decompression, minimum blood loss, radical discectomy, meticulous endplate preparation, cage insertion under direct visual control, and excellent treatment results with a high fusion rate and few complications.

A study on the effect of platelet-rich plasma (PRP) to promote bone fusion in lateral interbody fusion of the lumbar spine using artificial bone

BackgroundLateral lumbar interbody fusion (LLIF) via a retroperitoneum approach has gained popularity due to minimal invasiveness, which avoids resection of the spinous process and laminae. However, as challenges in grafting autogenous bone persist, artificial bone has been tested in Japan to fill the spinal cage. Platelet-rich plasma (PRP) contains growth factors and anti-inflammatory cytokines to promote cellular proliferation and repair damaged tissues. While the effects of PRP on tendon and ligament repair are widely known, any effects on bone healing are scarcely reported. However, PRP-loaded artificial bone carries potential to improve intervertebral bone fusion.ObjectiveThis study assessed whether PRP enhances intervertebral bone fusion in LLIF surgery using β-tricalcium phosphate artificial bone.MethodsThe current study was a prospective, randomized, controlled trial. We evaluated 13 consecutive patients undergoing LLIF surgery in our hospital. Patients received artificial bone impregnated with PRP or without PRP within the same fusion cage. The primary outcome was the intervertebral bone fusion rate at 6 and 12 months postoperatively, evaluated using CT imaging. The intervertebral bone fusion rates with and without PRP loading and with and without contact part between the endplate and the artificial bone were compared. Secondary outcomes included clinical evaluations using visual analog scale scores for low back pain, buttock-leg pain, and leg numbness from the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOA-BPEQ) and the Oswestry Disability Index (ODI), plus adverse events information.ResultsOf the 13 patients (29 vertebral segments) included, bone fusion was observed in 43.4% of the PRP group and 26.1% of the non-PRP group at 6 months (p = 0.216). At 12 months, fusion rates were 60.9% with PRP and 34.8% without PRP (p = 0.074). The fusion rate was significantly higher in cases with good contact between the vertebral endplate and the artificial bone (p = 0.0004). Clinical scores improved postoperatively. Adverse events were in accordance with expectations from LLIF surgery and no PRP-specific events occurred.ConclusionPRP did not significantly improve intervertebral bone fusion rates in LLIF surgeries, particularly in cases with poor contact between the vertebral endplate and artificial bone. While PRP may have a limited role in enhancing bone fusion, maintaining good contact between the vertebral endplate and artificial bone is crucial for successful outcomes. Further research is needed to explore optimal uses of PRP in spinal fusion surgeries.

Novel Technique for Degenerative Lumbar Spine Fusion: Unilateral Pedicle Screw Fixation Combined with Contralateral Interbody Cage Fusion for Posterior Lumbar Interbody Fusion

Abstract Objective The common traditional surgical techniques for posterior lumbar interbody fusion (PLIF) and fixation are bilateral pedicle screw fixation with or without interbody cage fusion and unilateral pedicle screw fixation with ipsilateral cage fusion. However, the novel unilateral pedicle screw fixation combined with the contralateral interbody cage fusion technique may provide the benefits and avoid the hazards of those traditional techniques. This prospective randomized comparative clinical trial aims to compare pedicle screw fixation with contralateral interbody cage fusion and unilateral pedicle screw fixation with ipsilateral cage fusion in single-level PLIF and fixation. Methods This comparative prospective study was conducted on 60 patients subjected to a single-level PLIF and unilateral pedicle screw fixation during the period from January 2022 to July 2022 to compare two different surgical modalities: group A (unilateral pedicle screw fixation with contralateral interbody cage fusion) and group B (unilateral pedicle screw fixation with ipsilateral cage fusion). Results Operative time, blood loss, operative complications, and visual analog scale improvements showed insignificant differences between the two groups, while group A showed significant improvements in the Oswestry Disability Index and wider coronal disc heights contralateral to the screw, which is the side of the cages, during postoperative follow-up. Conclusion Unilateral pedicle screw fixation with contralateral cage fusion during the PLIF and pedicle screw fixation procedure is preferred to maintain bilateral coronal disc heights and thus better clinical and mechanical results without affection of the preceding disc.

Surgical management of thoracolumbar burst fractures by three different posterior techniques: A prospective comparative study

Study designProspective Comparative Study. ObjectivesThis study aims to study the outcome of thoracolumbar burst fractures by comparison of 3 different posterior constructs groups of patients treated by the posterior approach. SettingUniversity level Tertiary care Centre of Northern India. MethodsSingle centre study conducted from September 2020 to April 2022, the study included patients aged 18–50 years with burst fractures in the thoracolumbar region, TLICS score ≥4, and injury surgery duration <3 weeks. Sixty patients were divided into three groups: Group I (short segment with index screw(s) in the fractured vertebrae), Group II (short segment with interbody cage fusion), and Group III (long segment without index screw or interbody cage). Clinical and radiological assessments were performed over a 6-month follow-up period. Outcome measures included the Visual Analog Scale (VAS) for pain, Oswestry Disability Index (ODI), American Spinal Injury Association (ASIA) impairment scale, and radiological parameters. ResultsAmong 60 patients, 38 were male, and 22 were female, with a mean age of 33.37 ± 12.26 years. The most common injury mechanisms were falls from heights (85 %). Group I had the lowest estimated blood loss (395 ± 36.20 ml) and shortest surgery duration (140 ± 26.56 min), while Group III had the highest blood loss (744.25 ± 113.69 ml) and longest surgery duration (203.50 ± 23.40 min). No statistically significant differences were observed in kyphosis correction, canal clearance, or fusion status among the groups. Neurological and functional outcomes improved across all groups, with no significant intergroup differences. ConclusionAll three posterior instrumentation constructs provided effective management of thoracolumbar burst fractures, demonstrating high rates of fusion, significant kyphosis correction, and minimal loss of alignment. Despite variations in surgical parameters such as estimated blood loss and surgery duration, the clinical and radiological outcomes were comparable. Level of evidenceIII.

Correlation Between Quantitative Cage Pressure Measurements and Surgeons' Qualitative Tactile Assessments During Extraction in Lumbar Lateral Interbody Fusion: A Cadaveric Study.

A cadaveric study. Measuring the pressure exerted on lumbar lateral interbody fusion (LLIF) cages and examining its correlation with qualitative assessment of tactile feedback related to pullout strength during cage extraction to determine the optimal cage height. No data exists on the relationship between the surgeon's tactile feedback related to pullout strength during the LLIF cage extraction and the cage pressures measured during surgery. We used four cadavers to insert the original stress-measuring cages at the L2/3 to L4/5 levels (12 intervertebral spaces) using the oblique lumbar lateral approach. The intervertebral disc height (IDH) was measured before cage insertion. These stainless-steel stress-measuring cages were designed with the same shape as standard cages and included a built-in load cell to measure the stress applied. The cage heights were set at 8, 10, and 12 mm and they were inserted sequentially from 8mm, with stress measurements taken at each step. Four spine surgeons qualitatively evaluated the extraction strength using three rating categories ("loose," "appropriate," and "hard to extract"). After cage removal, endplate damage (ED) and anterior longitudinal ligament injury (ALLI) were checked. The anterior part of the vertebral body was dissected to expose the ALL and it is checked for obvious injuries. Additionally, a surgical probe is used to check for ED and ALLI. The measured cage pressures were 45, 120, and 191 N for the "loose," "appropriate," and "hard to extract" ratings, respectively (P < 0.001). ED was observed in five intervertebral spaces, whereas no ALLI was noted. The average maximum pressure when ED occurred was 127 N. The primary risk factor for ED was identified as the difference between the height of the inserted cage and IDH, with a cut-off value of 4.5mm. The appropriate extraction strength corresponded to a cage pressure of 120 N. A cage pressure ≥127 N posed a risk for ED. ED incidence was high when the difference between the IDH and the height of the inserted cage exceeded 4.5mm. Level Three.

Free Vascularized Scapula tip Flap to L5—S1 Vertebral Defect After Chronic Infection Related to Interbody Fusion Cage: A Case Report

ABSTRACTSeptic nonunion after vertebral fusion can lead to significant patient disability. The management of septic nonunions usually involves surgical debridement, bone fixation, and antibiotic therapy. Particularly challenging is lumbosacral vertebral nonunions, which necessitate a difficult surgical approach. We present a novel approach using a scapula tip free flap through an intra‐abdominal approach to reconstruct a L5–S1 vertebral defect after a septic nonunion. Our patient, 31‐year‐old man, with no medical conditions, had a fusion of L5–S1 due to severe lower back pain secondary to isthmic spondylolysis and spondylolisthesis. Despite multiple attempts of surgical fusion, postoperatively the patient developed a septic nonunion. Following a modified DAIR, the nonunion was reconstructed with a scapula tip bone flap 4 × 3 × 2 cm. The subscapular vessels were anastomosed to the deep inferior epigastric vessels after an intra‐abdominal inset. The patient was discharged at 15 days postoperatively without any complications. At 1‐year follow‐up the patient is pain‐free, off opiate analgesia with radiological evidence of fusion between the scapula tip, L5 and the S1 vertebral body. This case report describes the use, for the first time, of a free scapula tip, to a lumbosacral spinal defect. The use of the free scapula tip flap may be considered for reconstruction of osseous spinal defects due to its long pedicle and the unique bone shape.

Comparative Biomechanical Analysis of Anterior Lumbar Interbody Fusion and Bilateral Expandable Transforaminal Lumbar Interbody Fusion Cages: A Finite Element Analysis Study.

Expandable transforaminal lumbar interbody fusion (TLIF) cages could offer an alternative to anterior lumbar interbody fusion (ALIF). Bilateral cage insertion enhances endplate coverage, potentially improving stability and fusion rates and maximizing segmental lordosis. This study aims to compare the biomechanical properties of bilateral expandable TLIF cages to ALIF cages using finite element modeling. We used a validated 3-dimensional finite element model of the lumbar spine. ALIF and TLIF cages were created based on available product data. Our focus was on analyzing spinal motion in the sagittal plane, evaluating forces transmitted through the vertebrae, and comparing an ALIF model with various TLIF cage models. The largest TLIF cage model exhibited a 407.9% increase in flexion motion and a 42.1% decrease in extension motion compared with the ALIF cage. The second largest TLIF cages resulted in more flexion motion and less extension motion compared with ALIF, while smaller cages were inferior to ALIF. ALIF cages were associated with increased adjacent segment motion compared with TLIF cages, primarily in extension. Endplate stress analysis revealed higher stress in the ALIF cage model with a more uniform stress distribution. ALIF cages excel in stabilizing L5 to S1 during flexion, while largest TLIF cages offer superior stability in extension. Large bilateral TLIF cages may provide biomechanical stability comparable to ALIF, especially in extension and could potentially reduce the risk of adjacent segment disease with lower adjacent segment motion.

Feasibility of the Non-Window-Type 3D-Printed Porous Titanium Cage in Posterior Lumbar Interbody Fusion: A Randomized Controlled Multicenter Trial.

Three-dimensionally printed titanium (3D-Ti) cages can be divided into 2 types: window-type cages, which have a void for bone graft, and non-window-type cages without a void. Few studies have investigated the necessity of a void for bone graft in fusion surgery. Therefore, the present study assessed the clinical and radiographic outcomes of window and non-window-type 3D-Ti cages in single-level posterior lumbar interbody fusion. A total of 70 patients were randomly assigned to receive either a window or non-window cage; 61 patients (87%) completed final follow-up (32 from the window cage group, 29 from the non-window cage group). Radiographic outcomes, including fusion rates, subsidence, and intra-cage osseointegration patterns, were assessed. Intra-cage osseointegration was measured using the intra-cage bridging bone score for the window cage group and the surface osseointegration ratio score for the non-window cage group. Additionally, we looked for the presence of the trabecular bone remodeling (TBR) sign on computed tomography (CT) images. Of the 61 patients, 58 achieved interbody fusion, resulting in a 95.1% fusion rate. The fusion rate in the non-window cage group was comparable to, and not significantly different from, that in the window cage group (96.6% and 93.8%, p > 0.99). The subsidence rate showed no significant difference between the window and non-window cage groups (15.6% and 3.4%, respectively; p = 0.262). The intra-cage osseointegration scores showed a significant difference between the groups (p = 0.007), with the non-window cage group having a higher proportion of cases with a score of 4 compared with the window cage group. The TBR sign was observed in 87.9% of patients who achieved interbody fusion, with a higher rate in the non-window cage group across the entire cohort although the difference was not significant (89.7% versus 78.1%, p = 0.385). Non-window-type 3D-Ti cages showed equivalent clinical outcomes compared with window-type cages and comparable interbody fusion rates. These results suggest that the potential advantages of 3D-Ti cages could be optimized in the absence of a void for bone graft by providing a larger contact surface for osseointegration. Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Endochondral Ossification for Spinal Fusion: A Novel Perspective from Biological Mechanisms to Clinical Applications.

Degenerative scoliosis (DS), encompassing conditions like spondylolisthesis and spinal stenosis, is a common type of spinal deformity. Lumbar interbody fusion (LIF) stands as a conventional surgical intervention for this ailment, aiming at decompression, restoration of intervertebral height, and stabilization of motion segments. Despite its widespread use, the precise mechanism underlying spinal fusion remains elusive. In this review, our focus lies on endochondral ossification for spinal fusion, a process involving vertebral development and bone healing. Endochondral ossification is the key step for the successful vertebral fusion. Endochondral ossification can persist in hypoxic conditions and promote the parallel development of angiogenesis and osteogenesis, which corresponds to the fusion process of new bone formation in the hypoxic region between the vertebrae. The ideal material for interbody fusion cages should have the following characteristics: (1) Good biocompatibility; (2) Stable chemical properties; (3) Biomechanical properties similar to bone tissue; (4) Promotion of bone fusion; (5) Favorable for imaging observation; (6) Biodegradability. Utilizing cartilage-derived bone-like constructs holds promise in promoting bony fusion post-operation, thus warranting exploration in the context of spinal fusion procedures.

Building a Stronger Backbone: 3D Printing's Role in Treating Spinal Cord Conditions

AbstractSpinal cord injuries (SCIs) pose significant challenges as complete nerve regeneration remains limited. The demand for improved technologies in SCI treatment is evident. One such emerging technology is three-dimensional printing (3DP), which, coupled with advancements in medical imaging and bioengineering, has significantly enhanced precision in surgical procedures. This systematic review aims to explore 3DP as a treatment option for SCIs, examining its cost, efficacy, safety, and the associated technological constraints. A systematic search of Medline was conducted through PubMed for literature published since 2019. The search results were exported to Rayyan for abstract and full-text screening following predefined criteria. The risk of bias in the selected studies was assessed using the RoB2 tool and the Newcastle-Ottawa Scale. From a total of 89 articles screened, 11 studies met the eligibility criteria, collectively assessing 237 individuals with various types of SCIs, including lumbar degeneration, en bloc resection of thoracolumbar metastasis, adult spinal deformity, and cervical degeneration. These studies examined the utilization of 3DP devices such as hand orthosis, interbody fusion cages, lamellar titanium cages, artificial vertebral bodies, and others. Most of the reviewed studies reported positive treatment outcomes, with the actual procedure costs varying from $65 to $5,000. Recent literature shows positive outcomes in the use of 3DP technologies for SCIs, highlighting its potential for enhancing both surgical and nonsurgical interventions. These advancements usher in a new era in SCI treatment, providing enhanced precision and a wider range of treatment options, ultimately leading to more comprehensive and effective patient care.

An analysis of clinical application effects of 3d-printed act titanium trabecular intervertebral fusion cage in posterior lumbar interbody fusion (PLIF).

To compare the clinical effects of applying a 3D-printed ACT titanium trabecular intervertebral fusion cage and a Polyetheretherketone (PEEK) cage in posterior lumbar interbody fusion (PLIF). This was a clinical comparative study. Forty patients with degenerative lumbar diseases admitted at The Second People's Hospital of Dalian from January 2020 to December 2021 were selected and divided into an observation group (3D cage) and a control group (PEEK cage) using the random number table method, with each group of 20 cases. The visual analogue scale (VAS) scores, Japanese Orthopaedic Association (JOA) scores, Cobb angles at fusion segments, intervertebral height and intervertebral fusion situations of the patients between the groups were compared. No significant differences were found in their operation time, intraoperative blood losses and operation related complications(p>0.05). In terms of postoperative VAS and JOA scores in both groups, they are all significantly improved compared with those before the operation, and their differences are also statistically significant(p<0.05). However, no statistical significance exists in inter-group differences(p>0.05). Postoperative Cobb angles and intervertebral height of patients in both groups are considerably bettered compared with those before the operation. Their differences show statistical significance(p<0.05), while inter-group differences are proved to be not statistically significant(p>0.05). Applying a 3D-printed ACT titanium trabecular intervertebral fusion cage or PEEK cage in PLIF has the potential to improve clinical symptoms of patients with degenerative lumbar diseases, and restore the Cobb angle and intervertebral height. 3D-printed ACT titanium trabecular intervertebral fusion cage can accelerate intervertebral fusion without increasing operation related complications.

Expandable versus static transforaminal lumbar interbody fusion (TLIF) cages: comparing radiographic outcomes and complication profiles

Background ContextExpandable transforaminal lumbar interbody fusion (TLIF) cages have become popular in recent years due to anticipated advantages of increased disc height, improved segmental lordosis, and ease of implantation. Such benefits have not been conclusively demonstrated in the literature. PurposeTo determine whether expandable cages increase disc height and segmental lordosis in a durable way following surgery and compare complication profiles between cage types. Study Design/SettingRetrospective cohort study conducted within a large academic health system involving 31 different spine surgeons. Patient SampleAdults undergoing single-level TLIF for an indication other than infection, tumor, trauma, or revision instrumentation from 2021 to 2023. Outcome MeasuresOur primary outcomes were changes in segmental disc height, segmental lordosis, and L4-S1 lordosis at 2 weeks, 6 months, and 1 year following surgery relative to baseline. Our secondary outcomes were frequencies of incidental durotomies, surgical site infections, readmissions, death, subsidence, and unplanned return to the operating room. MethodsRadiographic variables were collected from our institutional imaging registry. Demographics and surgical characteristics were abstracted from chart review. Generalized linear modeling was used for each primary outcome, with cage type (expandable vs. static) as our primary predictor and age, biologic sex, race, CCI, year of surgery, duration of surgery, invasiveness of surgery, surgeon specialty (Orthopedics vs. Neurosurgery), and level of surgery as covariates. ResultsOur cohort consisted of 417 patients with a mean age of 62. Static cages were used in 306 patients and expandable cages in 111. Expandable cages were associated with increased changes in disc height relative to static cages at 2 weeks (1.1 mm [0.2–1.9]; p=.01) and 6 months (1.2 mm [0.2–2.3]; p=.02) following surgery, but differences were no longer significant at 1 year (0.4 mm [−0.9–1.8]; p=.4). Expandable cages were found to subside more commonly than static cages (14.1% vs. 6.6%; p=.04). No significant differences between cage types were identified in lordotic parameters at any timepoint (p=0.25 to p=0.97). ConclusionsExpandable cages were associated with an initial increase in disc height relative to static cages, but this difference diminished with the first year of surgery, likely due to a higher rate of subsidence within the expandable cohort.

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.

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.

Advancements in Custom 3D-Printed Titanium Interbody Spinal Fusion Cages and Their Relevance in Personalized Spine Care.

3D-printing technology has revolutionized spinal implant manufacturing, particularly in developing personalized and custom-fit titanium interbody fusion cages. These cages are pivotal in supporting inter-vertebral stability, promoting bone growth, and restoring spinal alignment. This article reviews the latest advancements in 3D-printed titanium interbody fusion cages, emphasizing their relevance in modern personalized surgical spine care protocols applied to common clinical scenarios. Furthermore, the authors review the various printing and post-printing processing technologies and discuss how engineering and design are deployed to tailor each type of implant to its patient-specific clinical application, highlighting how anatomical and biomechanical considerations impact their development and manufacturing processes to achieve optimum osteoinductive and osteoconductive properties. The article further examines the benefits of 3D printing, such as customizable geometry and porosity, that enhance osteointegration and mechanical compatibility, offering a leap forward in patient-specific solutions. The comparative analysis provided by the authors underscores the unique challenges and solutions in designing cervical, and lumbar spine implants, including load-bearing requirements and bioactivity with surrounding bony tissue to promote cell attachment. Additionally, the authors discuss the clinical outcomes associated with these implants, including the implications of improvements in surgical precision on patient outcomes. Lastly, they address strategies to overcome implementation challenges in healthcare facilities, which often resist new technology acquisitions due to perceived cost overruns and preconceived notions that hinder potential savings by providing customized surgical implants with the potential for lower complication and revision rates. This comprehensive review aims to provide insights into how modern 3D-printed titanium interbody fusion cages are made, explain quality standards, and how they may impact personalized surgical spine care.

Biomimetic Porous Ti6Al4V Implants: A Novel Interbody Fusion Cage via Gel-Casting Technique to Promote Spine Fusion.

An interbody fusion cage (Cage) is crucial in spinal decompression and fusion procedures for restoring normal vertebral curvature and rebuilding spinal stability. Currently, these Cages suffer from issues related to mismatched elastic modulus and insufficient bone integration capability. Therefore, a gel-casting technique is utilized to fabricate a biomimetic porous titanium alloy material from Ti6Al4V powder. The biomimetic porous Ti6Al4V is compared with polyetheretherketone (PEEK) and 3D-printed Ti6Al4V materials and their respective Cages. Systematic validation is performed through mechanical testing, in vitro cell, in vivo rabbit bone defect implantation, and ovine anterior cervical discectomy and fusion experiments to evaluate the mechanical and biological performance of the materials. Although all three materials demonstrate good biocompatibility and osseointegration properties, the biomimetic porous Ti6Al4V, with its excellent mechanical properties and a structure closely resembling bone trabecular tissue, exhibited superior bone ingrowth and osseointegration performance. Compared to the PEEK and 3D-printed Ti6Al4V Cages, the biomimetic porous Ti6Al4V Cage outperforms in terms of intervertebral fusion performance, achieving excellent intervertebral fusion without the need for bone grafting, thereby enhancing cervical vertebra stability. This biomimetic porous Ti6Al4V Cage offers cost-effectiveness, presenting significant potential for clinical applications in spinal surgery.

Quantitative Threshold of Intraoperative Radiological Parameters for Suspecting Oblique Lumbar Interbody Fusion Cage Malposition Triggering Contralateral Radiculopathy.

This study aimed to clarify the quantitative threshold of intraoperative radiological parameters for suspecting posterior malposition of the oblique lumbar interbody fusion (OLIF) cage triggering contralateral radiculopathy. We measured the sagittal center and axial rotation angle (ARA) of the cage using postoperative computed tomography (CT) in 130 patients (215 cages) who underwent OLIF. The location of the cage tip was determined from axial magnetic resonance imaging in selected cases based on CT simulations to assess whether the cage was in contact with the contralateral exiting nerve or whether the surgical instruments could contact the nerve during intradiscal maneuvers. The sagittal center of the cages was on average 41.5% from the anterior edge of the endplate (shown as AC/AP value: anterior end plate edge-cage center/anterior-posterior endplate edge ×100%), and posterior cage positioning ≥50% occurred in 14% of the cages. The ARA was -2.9°, and posterior oblique rotation of the cages ≥10° (ARA ≤ -10°) was observed in 13%. CT simulation showed that the cage tip could directly contact the contralateral nerve when the cage was placed deep in the posterior portion ≥50% of the AC/AP values with concomitant posterior axial rotation ≥10° (ARA ≤ -10°), or deep in an extremely rare portion ≥60% of the AC/AP values with posterior axial rotation ≥0° (ARA ≤ 0°). Six percent of the cages (13/215) were placed in these posterior oblique areas (potential contact area: PCA). Three cages in the PCA were in direct contact with the contralateral nerves, and 9 were placed deep just anterior to the nerves. Symptomatic contralateral radiculopathy occurred in 2 cages (2/13/215, 15.3%/0.9%). Two intraoperative radiological parameters (AC/AP and ARA) measurable during OLIF procedures may become practical indicators for suspecting cage malposition in PCA and may be available when determining whether to consider cage revision intraoperatively to a more ventral disc space or anteriorly from the opposite endplate edge.

The postoperative clinical effects of utilizing 3D printed (Ti6Al4V) interbody fusion cages in posterior lumbar fusion: A retrospective cohort study.

The research focused on the postoperative effect of using interbody fusion cage in lumbar posterior lamina decompression and interbody fusion with pedicle screw by comparing the postoperative effect of using 3D printing (Ti6Al4V) and PEEK material interbody fusion cage. Ninety-one patients with lumbar degenerative diseases from the Department of Spine Surgery of Tianjin Hospital were included in the study cohort. They were divided into 3D group (n = 39) and PEEK group (n = 52) according to the use of interbody fusion cage. The imaging data of the patients were collected and the postoperative data of the 2 groups were compared to evaluate patients' health status and the recovery of lumbar structure and function after operation. Combined with the degree of fusion, the clinical effect of 3D printing titanium alloy interbody fusion cage was comprehensively judged. At the last follow-up, the JOA score, ODI index, VAS, prolo function score, and SF-36 scale of the 2 groups showed that the clinical symptoms were better than those before operation (P < .05). The height of intervertebral disc, the area of intervertebral foramen and the physiological curvature of lumbar vertebrae increased in varying degrees after operation (P < .05). At the last follow-up, the vertebral cage fusion rates were as high as 89.13% and 90.91% in the 3D and PEEK groups, with collapse rates of 6.5% and 4.5%, respectively. There were 10 cases of cage displacement in 3D group and 7 cases of cage displacement in PEEK group. There was no significant difference between the 2 groups (P > .05). In conclusion, 3D printed (Ti6Al4V) interbody fusion cage can obtain good clinical effect in the surgical treatment of lumbar degenerative diseases. Posterior lumbar lamina decompression, bilateral pedicle screw fixation combined with 3D printed cage interbody fusion is excellent in rebuilding the stability of lumbar vertebrae. 3D printed interbody fusion cage can be an ideal substitute material for intervertebral bone grafting. The stable fusion time of interbody fusion cage after lumbar fusion is mostly from 3 months to half a year after operation.