Experimental Study of Spinal Reconstruction Using Bioabsorbable Material

本研究的目的是通过影像学、生物力学和组织学评价未煅烧羟基磷灰石聚乳酸椎间融合器（F-u-HA/PLLA）锻造复合材料与传统自体髂骨（AM）和碳纤维椎间融合器（CFC）相比的有效性和优势。25只成年绵羊在L2-3节段接受后路椎弓根螺钉系统椎间融合术。植入AIB（n=7）、CFC（n=9）、F-u-HA/PLLA（n=9）3种椎间融合器。两种类型的融合器填充有局部采集的自体碎片松质骨。所有动物在手术后120天处死。融合评分采用冠状位CT扫描，旨在三维评价融合器内和周围的融合质量。三组的平均CT评分AIB、CFC和F-u-HA/PLLA融合器组分别为33.3分、35.0分和33.6分（总分56分）。三组间无统计学差异。在所有纯力矩载荷下，融合组之间的平均活动度值无显著差异。关节活动度与CT融合评分有很强的相关性。组织学结果显示F-u-HA/PLLA融合器与周围骨直接接触，CFC被厚纤维组织层包围，融合器周围无任何炎症迹象。无论从影像学还是生物力学角度来看，使用F-u-HA/PLLA融合器融合的脊柱节段的融合质量均与AIB或CFC相当。在组织学观察中，F-u-HA/PLLA融合器的生物相容性明显上级CFC。已经证实，新型生物活性和生物可吸收融合器在脊柱重建手术中的使用比现有CFC具有宝贵的优势。

Objectives of the study were to evaluate the validity and advantage of forged composite of uncalcined hydroxyapatite Poly L-Lactite cage (F-u-HA/PLLA) radiographically, biomechanically, and histlogically when compared to conventional autologousiliac bone (AM) and carbon fiber cage (CFC). Twenty-five mature sheep underwent posterior lumbar interbody fusion at L2-3 level with pedide screw system. Three types of interbody fusion implants were grafted : AIB (n=7), CFC (n=9), F-u-HA/PLLA((n=9). Two types of cages were packed with autologous fragmented cancellous bone harvested locally. All animals were euthanized at 120 days after surgery. The fusion scoreing using the coronal view CT scans was designed to three dimentionally evaluate fusionquality within and around cages. The meen CT scores of threee groups were 33.3 points, 35.0 points, 33.6 points in AIB, CFC, and F-u-HA/PLLA cage groups, respectively (full-score : 56 points). Statistical differences were not detected among the three groups. The mean range of motion values among fused groups had no significant diffierence under all pure moment loadings. The range of motion showed strong and significant correlation with the CT fusion scores. Histologic results demonstrated that F-u-HA/PLLA cages contacted with the surrounding bone directly, and CFC was encircled with thick fibrous tissue layrs without any sign of inflammation around cages. The fusion quality of fused spinal segment using F-u-HA/PLLA cages was equal to that of AIB or CFC both radiographically and biomechanically. In the histological observation, biocompatibility of F-u-HA/PLLA cage was obviously superior to CFC. It has been confirmed that the novel bioactive and bioabsorbable cages had valuable advantages over existing CFC for use in spinal re constructive surgery.