Biomechanical study of a hat type cervical intervertebral fusion cage.
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ABSTRACT:
SUBMITTER: Gu YT
PROVIDER: S-EPMC2267542 | biostudies-other | 2007 Feb
REPOSITORIES: biostudies-other
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Project description:ObjectiveTo evaluate the change in ex vivo biomechanical properties of the canine cervical spine, due to an intervertebral cage, both as a stand-alone device and in combination with plates.Study designExperimental ex vivo study.AnimalsCervical spinal segments (C5-C7) from eight canine cadavers.MethodsThe range of motion (ROM) and elastic zone stiffness (EZS) of the spines were determined with a four-point bending device in flexion/extension, lateral bending, and axial rotation for four conditions: native, discectomy, cage (at C6-C7), and cage with plates (at C6-C7). The disc height index (DHI) for each condition was determined using radiography.ResultsDiscectomy resulted in overall increased ROM (p < .01) and EZS (p < .05) and decreased DHI (p < .005) when compared to the native condition. Placement of the cage increased DHI (p < .001) and restored total ROM during flexion/extension, lateral bending and axial rotation, and EZS during flexion/extension to the level of the native spine. Application of the plates further reduced the total ROM during flexion/extension (p < .001) and lateral bending (p < .001), but restored ROM in extension and EZS during lateral bending. No implant failure, subsidence, or significant cage migration occurred during loading.ConclusionAn anchorless intervertebral cage used as a stand-alone device was able to restore the disc height and spinal stability to the level of the native cervical spine, whereas the addition of plates further reduced the spinal unit mobility.Clinical significanceThis study implies that the intervertebral cage may be used as a stand-alone device in the spinal unit fixation in the canine cervical spine.
| S-EPMC8360106 | biostudies-literature
Project description:BackgroundEndplate morphology is considered to be one of the influencing factors of cage subsidence after lumbar interbody fusion (LIF). Previous radiographic evaluations on the endplate mostly used sagittal X-ray or MRI. However, there are few studies on the CT evaluation of the endplate and intervertebral space (IVS), especially the evaluation of coronal morphology and its influence on subsidence and fusion after LIF. We aimed to measure and classify the shapes of the endplate and IVS using coronal CT imaging and evaluate the radiographic and clinical outcomes of different shapes of the endplate/IVS following oblique lateral lumbar interbody fusion (OLIF).MethodsA total of 137 patients (average age 59.1 years, including 75 males and 62 females) who underwent L4-5 OLIF combined with anterolateral fixation from June 2018 to June 2020 were included. The endplate concavity depth (ECD) was measured on the preoperative coronal CT image. According to ECD, the endplate was classified as flat (< 2 mm), shallow (2-4 mm), or deep (> 4 mm). The L4-5 IVS was further classified according to endplate type. The disc height (DH), DH changes, subsidence rate, fusion rate, and Oswestry Disability Index (ODI) in different endplate/IVS shapes were evaluated during 1-year follow up.ResultsThe ECD of L4 inferior endplate (IEP) was significantly deeper than that of L5 superior endplate (SEP) (4.2 ± 1.1 vs 1.6 ± 0.8, P < 0.01). Four types of L4-5 IVS were identified: shallow-shallow (16, 11.7%), shallow-flat (45, 32.9%), deep-shallow (32, 23.4%), and deep-flat (44, 32.1%). A total of 45 (32.9%) cases of cage subsidence were observed. Only one (6.3%) subsidence event occurred in the shallow-shallow group, which was significantly lower than in the other three groups (19 shallow-flat, 6 deep-shallow, and 19 deep-flat) (P < 0.05). Meanwhile, the shallow-shallow group had the highest fusion rate (15, 93.8%) and the highest rate of reach minimal clinically important difference (MCID) ODI among the four types. For a single endplate, the shape of L4 IEP is the main influencing factor of the final interbody fusion rate, and the shallow shape L4 IEP facilitates fusion ( OR = 2.85, p = 0.03). On the other hand, the flat shape L5 SEP was the main risk factor to cage subsidence (OR = 4.36, p < 0.01).ConclusionThe L4-5 IVS is asymmetrical on coronal CT view and tends to be fornix-above and flat-down. The shallow-shallow IVS has the lowest subsidence rate and best fusion result, which is possibly because it has a relatively good degree in matching either the upper or lower interface of the cage and endplates. These findings provide a basis for the further improvements in the design of OLIF cages.
| S-EPMC9252057 | biostudies-literature
Project description:Favorable bone fusion and clinical results have been reported for anterior cervical fusion (ACF) using titanium interbody cage (TIC). This method might induce postoperative subsidence and local kyphosis, but the relationship between radiological changes and preoperative local alignment is not known. The purpose of the present study is to investigate the impact of preoperative local alignment on the clinical and radiological outcomes of ACF using TIC.The study enrolled 36 patients (mean age 49.8 years) who underwent single-level ACF using TIC for cervical degenerative diseases. Patients were divided into 2 groups by preoperative segmental lordotic angle at the operative level: group L, ≥0° (n = 16); group K, <0° (n = 20). Clinical outcomes included recovery rate according to the Japanese Orthopaedic Association score and complication rates. Radiological assessment was conducted for the cervical and segmental lordotic angles, subsidence, and bone fusion. Mann-Whitney test and chi-square test were applied to compare the outcomes.The Japanese Orthopaedic Association score recovery rate was 77.2% in group L and 87.6% in group K, with no significant difference. No obvious complications were observed in any of the subjects. Mean cervical lordotic angles preoperatively and at last follow-up were 9.2 ± 9.5° and 11.3 ± 11.7°, respectively, in group L, and -1.3 ± 12.8° and 4.6 ± 13.3°, respectively, in group K. The mean segmental lordotic angles preoperatively and at last follow-up were 2.5 ± 2.2° and 2.6 ± 5.7°, respectively, in group L, and -4.5 ± 2.8° and -1.4 ± 5.8°, respectively, in group K. In group K, the cervical and segmental lordotic angles at the last follow-up were significantly greater than the preoperative angles. The change observed in group L was not significant. Subsidence of ≥3 mm was observed in 3 patients in group L and 4 patients in group K. None of the patients showed nonunion.Anterior cervical fusion using TIC provided favorable clinical results regardless of preoperative segmental alignment. Although postoperative subsidence and kyphotic changes are concerns in patients presenting segmental kyphosis, ACF using TIC corrected both the entire cervical spine and segmental alignment. The TIC is useful for correction of the cervical alignment for patients with cervical degenerative disease with local kyphotic changes.
| S-EPMC5556228 | biostudies-other
Project description:BackgroundTreatment of atlantoaxial dislocation is aimed at reduction and stabilization of the atlantoaxial joint. 3D printing refers to a process where additive manufacturing is achieved under precise computer control. Literature on its utilization in anterior atlantoaxial fixation and fusion is rare. This study is the first report on a 3D-printed locking cage used in the anterior procedure for atlantoaxial dislocation.MethodsA middle-aged male in his 40s presented with weakness and numbness of his extremities for 3 years and could only walk slowly with assistance. Imaging studies revealed severe anterior migration of C1, irreducible atlantoaxial dislocation, and severe cervical-medullary compression. A preoperative plan consisting of trans-oral soft tissue release and fixation using tailor-designed 3D-printed cages was devised. Following fluoroscopic confirmation of reduction of the atlantoaxial joints, two customized 3D-printed cages made of titanium alloy were inserted into the bilateral facet joints, which were then locked by six screws into the lateral masses of C1 and C2. The microstructure of the inserted cages was optimized for improved biomechanical stability and enhanced osseo-integration, without the need for bone grafting. In addition, a biomechanical test was performed on seven human cadaveric specimens comparing the novel implant with the conventional C1 lateral mass-C2 pedicle screw construct in three modes of motion (flexion-extension, lateral bending, axial rotation).ResultsImprovement of neurologic function in the patient was evident immediately after surgery. He was able to walk independently 1 month post-operatively. At the 12-month follow-up, coronal reconstruction of CT demonstrated properly-positioned 3D-printed cages, evidence of osseo-integration at the bone-implant interface, and no subsidence or displacement of the implant. Eighteen months out of surgery, the mJOA score improved to 15, and lateral X-ray confirmed reduction of atlanto-axial dislocation. Additionally, the new construct provided strong fixation comparable to that conferred by conventional constructs as there was no significant difference observed between the two groups in all three directions of motion.ConclusionsThe novel implant represents a new option in the treatment of irreducible atlantoaxial dislocation. It can provide strong anterior support for solid fixation and fusion with a low profile and a microstructure that obviates the need for bone grafting.
| S-EPMC7844893 | biostudies-literature
Project description:BACKGROUND:To clarify the risk factors for subsidence of titanium mesh cage (TMC) following single-level anterior cervical corpectomy and fusion (ACCF) to reduce subsidence. METHODS:The present retrospective cohort study included 73 consecutive patients who underwent single-level ACCF. Patients were divided into subsidence (n?=?31) and non-subsidence groups (n?=?42). Medical records and radiological parameters such as age, sex, operation level, segmental angle (SA), cervical sagittal angle (CSA), height of anterior (HAE) and posterior endplate (HPE), ratio of anterior (RAE) and posterior endplate (RPE), the alignment of TMC, the global cervical Hounsfield Units (HU) were analyzed. Clinical results were evaluated using the Japanese Orthopedic Association (JOA) scoring system and the Visual Analog Scale (VAS). RESULTS:Subsidence occurred in 31 of 73 (42.5%) patients. Comparison between the groups showed significant differences in the value of RAE, the alignment of TMC and the global cervical HU value (p?<?0.001, p?=?0.002, p?<?0.001). In multivariate logistic regression analysis, RAE?>?1.18 (OR?=?6.116, 95%CI?=?1.613-23.192, p?=?0.008), alignment of TMC?>?3° (OR?=?5.355, 95%CI?=?1.474-19.454, p?=?0.011) and the global cervical HU value<?333 (OR?=?11.238, 95%CI?=?2.844-44.413, p?=?0.001) were independently associated with subsidence. Linear regression analysis revealed that RAE is significantly positive related to the extent of subsidence (r?=?-?0.502, p?=?0.006). CONCLUSION:Our findings suggest that the value of RAE more than 1.18, alignment of TMC and poor bone mineral density are the risk factors for subsidence. TMC subsidence does not negatively affect the clinical outcomes after operation. Avoiding over expansion of intervertebral height, optimizing placing of TMC and initiation of anti-osteoporosis treatments 6?months prior to surgery might help surgeons to reduce subsidence after ACCF.
| S-EPMC6961320 | biostudies-literature
Project description:PURPOSE: Partial wrist arthrodesis is a commonly performed procedure for the treatment of posttraumatic wrist arthritis because of its ability to provide pain relief without sacrificing complete wrist motion. The purpose of this study was to evaluate the redistribution of force after four-corner fusion and scaphoid excision, and to correlate the findings with the reported clinical outcomes. METHODS: Fifteen cadaveric wrists were used to study the biomechanics of the four-corner fusion. Pressure-sensitive film (super-low-pressure-indicating film-Pressurex, Sensor Products Inc, Madison, NJ) was inserted into the radiocarpal joint. Using the MTS 858 Mini Bionix (MTS System, Eden Prairie, MN), 50-kg loads (220 N) were applied to the wrists before and after simulated four-corner fusion and scaphoid excision. Statistically, we compared the pressure in the normal (intact) wrists versus four-corner fusion and scaphoid excision. The pressure measurements across the scaphoid fossa, lunate fossa, and triangular fibrocartilage complex (TFCC) were compared. RESULTS: There is a statistical significant difference between scaphoid, lunate, and TFCC mean total force when pre and post-fusion were compared (p = 0.0001). Our study revealed a statistical significant decrease in the mean scaphoid total force after scaphoid excision and four-corner fusion (p = 0.0001). We also found a subsequent increase in mean total force after scaphoid excision and four-corner fusion for the lunate fossa that did not reach statistical significance (p = 0.08), and no difference in load across the TFCC area (p = 0.995). CONCLUSIONS: Our findings suggest that load is preferentially transferred to the radiolunate joint after scaphoid excision with four-corner fusion.
| S-EPMC2527225 | biostudies-other
Project description:Several choices are available for cervical interbody fusion after anterior cervical discectomy. A recent option is dense cancellous allograft (CS) which is characterized by an open-matrix structure that may promote vascularization and cellular penetration during early osseous integration. However, the biomechanical stability of CS should be comparable to that of the tricortical iliac autograft (AG) and fibular allograft (FA) to be an acceptable alternative to these materials. The purpose of this study was to compare the initial biomechanical stability of CS to that of AG and FA in a one-level anterior cervical discectomy and interbody fusion (ACDF) model. Twelve human cervical spines (C3-T1) were loaded in six modes of motion and evaluated under three conditions: (1) intact, (2) after ACDF using CS, AG, and FA in alternating sequences, and (3) after ACDF with anterior plating. Three reflective markers were placed on the adjacent vertebral bodies. Intervertebral motion was measured with a video-based motion-capture system (MacReflex, Qualisys, Sweden). Torques were applied to a maximum of 2.0 N m. The range-of-motion and neutral-zone values measured in each loading mode were compared. No graft material displayed significant differences in biomechanical stability in any of the tested loading modes, suggesting that the initial stability of CS is comparable to that of AG and FA. Anterior cervical plating significantly increased biomechanical stability in all modes.
| S-EPMC2438562 | biostudies-other
Project description:BackgroundTransforaminal lumbar interbody fusion (TLIF) is an effective surgery for lumbar degenerative disease. However, this fusion technique requires resection of inferior facet joint to provide access for superior facet joint resection, which results in reduced lumbar spinal stability and unnecessary trauma. We have previously developed extraforaminal lumbar interbody fusion (ELIF) that can avoid back muscle injury with direct nerve root decompression. This study aims to show that ELIF enhances lumbar spinal stability in comparison to TLIF by comparing lumbar spinal stability of L4-L5 range of motion (ROM) on 12 cadaveric spine specimens after performing TLIF or ELIF.Methods12 cadaveric spine specimens were randomly divided and treated in accordance with the different internal fixations, including ELIF with a unilateral pedicle screw (ELIF+UPS), TLIF with a unilateral pedicle screw (TLIF+UPS), TLIF with a bilateral pedicle screw (TLIF+BPS), ELIF with a unilateral pedicle screw and translaminar facet screw (ELIF+UPS+TLFS) and ELIF with a bilateral pedicle screw (ELIF+BPS). The treatment groups were exposed to a 400-N load and 6 N·m movement force to calculate the angular displacement of L4-L5 during anterior flexion, posterior extension, lateral flexion and rotation operation conditions.ResultsThe ROM in ELIF+UPS group was smaller than that of TLIF+UPS group under all operating conditions, with the significant differences in left lateral flexion and right rotation by 36.15% and 25.97% respectively. The ROM in ELIF+UPS group was higher than that in TLIF+BPS group. The ROM in the ELIF+UPS+TLFS group was much smaller than that in the ELIF+UPS group, but was not significantly different than that in the TLIF+BPS group.ConclusionsDespite that TLIF+BPS has great stability, which can be comparable by that of ELIF+UPS. Additionally, ELIF stability can be further improved by using translaminar facet screws without causing more tissue damage to patient.
| S-EPMC5178989 | biostudies-literature
Project description:Biological approaches to intervertebral disc (IVD) restoration and/or regeneration have become of increasing interest. However, the IVD comprises a viscoelastic system whose biological replacement remains challenging. The present study sought to design load-sharing two-component model systems of circular, nested, concentric elements reflecting the nucleus pulposus and annulus fibrosus. Specifically, we wanted to investigate the effect of architectural design variations on (1) model system failure loads when testing the individual materials either separately or homogeneously mixed, and (2) also evaluate the potential of modulating other mechanical properties of the model systems. Two sets of softer and harder biomaterials, 0.5% and 5% agarose vs. 0.5% agarose and gelatin, were used for fabrication. Architectural design variations were realized by varying ring geometries and amounts while keeping the material composition across designs comparable. Variations in the architectural design, such as lamellar width, number, and order, combined with choosing specific biomaterial properties, strongly influenced the biomechanical performance of IVD constructs. Biomechanical characterization revealed that the single most important parameter, in which the model systems vastly exceeded those of the individual materials, was failure load. The model system failure loads were 32.21- and 84.11-fold higher than those of the agarose materials and 55.03- and 2.14-fold higher than those of the agarose and gelatin materials used for system fabrication. The compressive strength, dynamic stiffness, and viscoelasticity of the model systems were always in the range of the individual materials. Relevant architecture-promoted biomechanical performance-tuning of tissue-engineered constructs for biological IVD replacement can be realized by slight modifications in the design of constructs while preserving the materials' compositions. Minimal variations in the architectural design can be used to precisely control structure-function relations for IVD constructs rather than choosing different materials. These fundamental findings have important implications for efficient tissue-engineering of IVDs and other load-bearing tissues, as potential implants need to withstand high in situ loads.
| S-EPMC8160686 | biostudies-literature
