Healing of an anterior cruciate ligament (ACL) autologous graft in a bone tunnel occurs through the formation of fibrovascular scar tissue, which is structurally and compositionally inferior to normal fibrocartilaginous insertion and thus may increase the reconstruction failure and the rate of failure recurrence. In this study, an injectable hydroxyapatite/type I collagen (HAp/Col Ⅰ) paste was developed to construct a suitable local microenvironment to accelerate the healing of bone-tendon interface. Physicochemical characterization demonstrated that the HAp/Col Ⅰ paste was injectable, uniform and stable. The in vitro cell culture illustrated that the paste could promote MC3T3-E1 cells proliferation and osteogenic expression. The results of a canine ACL reconstruction study showed that the reconstructive ACL had similar texture and color as the native ACL. The average width of the tunnel, total bone volume, bone volume/tissue volume and trabecular number acquired from micro-CT analysis suggested that the healing of tendon-bone interface in experimental group was better than that in control group. The biomechanical test showed the maximal loads in experimental group achieved approximately half of native ACL's maximal load at 24 weeks. According to histological examination, Sharpey fibers could be observed as early as 12 weeks postoperatively while a typical four-layer transitional structure of insertion site was regenerated at 48 weeks in the experimental group. The injectable HAp/Col Ⅰ paste provided a biomimetic scaffold and microenvironment for early cell attachment and proliferation, further osteogenic expression and extracellular matrix deposition, and in vivo structural and functional regeneration of the tendon-bone interface.

前交叉韧带 (ACL) 自体移植物在骨隧道中的愈合是通过纤维血管瘢痕组织的形成而发生的，该组织在结构和成分上不如正常纤维软骨插入，因此可能会增加重建失败和失败复发率。本研究开发了一种可注射的羟基磷灰石/I型胶原（HAp/ColⅠ）糊剂，以构建合适的局部微环境，加速骨-腱界面的愈合。理化表征表明HAp/ColⅠ糊剂可注射、均匀、稳定。体外的细胞培养表明，该糊剂可促进MC3T3-E1细胞增殖和成骨表达。犬类 ACL 重建研究的结果表明，重建的 ACL 具有与原生 ACL 相似的纹理和颜色。显微CT分析获得的隧道平均宽度、总骨量、骨量/组织量和骨小梁数表明，实验组肌腱-骨界面愈合情况优于对照组。生物力学测试表明，实验组的最大负荷在 24 周时达到了自然 ACL 最大负荷的一半左右。根据组织学检查，术后12周即可观察到Sharpey纤维，而实验组在48周时再生出典型的插入部位四层过渡结构。可注射的 HAp/Col Ⅰ糊剂为早期细胞附着和增殖、进一步成骨表达和细胞外基质沉积提供了仿生支架和微环境，以及肌腱-骨界面的体内结构和功能再生。