Cheng Boyle C, Swink Isaac, Yusufbekov Rachelle, Birgelen Michele, Ferrara Lisa, Coric Domagoj
Department of Neurosurgery, Allegheny Health Network, Pittsburgh, Pennsylvania.
Integrity Implants, Inc, Palm Beach Gardens, Florida.
Int J Spine Surg. 2020 Dec;14(s3):S68-S74. doi: 10.14444/7129. Epub 2020 Oct 29.
Expandable cages that allow for bidirectional expansion, in both height and width, may offer benefits over traditional expandable cages or static cages. Effective stiffness must also be considered, as implants with exceedingly high stiffness may increase subsidence risk and reduce graft loading.
A retrospective case series of 7 patients were assessed with computed tomography (CT) scan at the final 1-year follow-up to evaluate the interbody fusion and configuration of the expandable cage related to the endplates within the intervertebral space. CT scans were reformatted using cage's tantalum markers as fiducials for single-plane orientation for each intervertebral cage. Device height and width at maximum in situ expansion was measured at its anterior and posterior aspects to evaluate implant deformation. The new bone volume within each cage was measured from the same CT scan data sets and by the Bridwell classification of interbody fusion.
The average difference between medial and lateral height measurements was 1.82 mm (±1.08) at the device's anterior aspect and 1.41 mm (±0.98) at the posterior aspect. The average difference between medial and lateral heights was 18.55% (±9.34) anteriorly and 15.49% (±9.24) posteriorly. There was a successful fusion in all 7 patients, as evidenced by measurable bone volume in the center of each interbody cage with an average of 586.42 mm (±237.06).
The authors demonstrated the feasibility of successfully using bidirectionally expandable multimaterial cages to achieve interbody fusion. These composite open-architecture cages were found to conform to each patient's endplate configuration. The authors' observations support the concept of material selection impacting the effective construct stiffness. The design investigated by the authors provided sufficient anterior column support and successful fusion in all patients.
可在高度和宽度上双向扩展的可扩张椎间融合器可能比传统的可扩张椎间融合器或静态椎间融合器更具优势。还必须考虑有效刚度，因为刚度极高的植入物可能会增加下沉风险并减少植骨负荷。
对7例患者进行回顾性病例系列研究，在最后1年随访时进行计算机断层扫描（CT），以评估椎间融合以及与椎间隙内终板相关的可扩张椎间融合器的形态。使用椎间融合器的钽标记物作为每个椎间融合器单平面定位的基准，对CT扫描进行重新格式化。在其前后方面测量原位最大扩张时的器械高度和宽度，以评估植入物变形。从相同的CT扫描数据集中测量每个椎间融合器内的新骨体积，并根据Bridwell椎间融合分类法进行评估。
在器械的前侧，内侧和外侧高度测量的平均差异为1.82毫米（±1.08），后侧为1.41毫米（±0.98）。内侧和外侧高度的平均差异在前侧为18.55%（±9.34），后侧为15.49%（±9.24）。所有7例患者均成功融合，每个椎间融合器中心均有可测量的骨体积，平均为586.42立方毫米（±237.06）。
作者证明了成功使用双向可扩张多材料椎间融合器实现椎间融合的可行性。发现这些复合开放式结构椎间融合器符合每个患者的终板形态。作者的观察结果支持材料选择影响有效结构刚度的概念。作者研究的设计为所有患者提供了足够的前柱支撑并实现了成功融合。
4级。
