A more flattened bone tunnel has a positive effect on tendon–bone healing in the early period after ACL reconstruction
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The purpose of this study was to evaluate whether a flattened bone tunnel has a positive effect on the tendon–bone healing (TBH) process in the early period after anterior cruciate ligament (ACL) reconstruction.
Seventy-two New Zealand White rabbits were randomly allocated into two groups, the flattened tunnel (FT) group and the conventional round tunnel (RT) group. We compared the cross-sectional areas and diameters of the bone tunnels between the two groups through computed tomography (CT) scanning. TBH results between the two groups were assessed by histological analysis, micro-CT scanning and biomechanical tests at 4 weeks, 8 weeks and 12 weeks after operation.
The cross-sectional areas of the bone tunnels between the two groups were almost the same. However, the shape of bone tunnels in the FT group was more flattened. A faster cellular and collagen remoulding process were found in the FT group. Semiquantitative histological analysis of Safranin O staining showed that there was more fibrocartilage formation in the interface region in the FT group (P < 0.05). Sirius Red staining showed that the tissues in the interface areas were more intense in the FT group. Micro-CT scanning showed that more new bone formation could be found in the interface region in the FT group. The biomechanical tests also showed that FT ACL reconstruction will result in a stronger regenerated tendon–bone interface.
Our study found that a flattened bone tunnel accelerated TBH in the early period after ACL reconstruction surgery in a rabbit model, which lays the groundwork for further clinical practice of this ACL reconstruction method.
KeywordsAnterior cruciate ligament Flattened Tendon-bone healing Ribbon-like
Anterior cruciate ligament
Region of interest
Bone volume/total volume
Intraclass correlation coefficient
The authors gratefully acknowledge Jiying Zhang, BS, Xiaoning Duan, BS and Xin Fu, BS for active participation in histological experiments.
Fengyuan Zhao carried out the ACL reconstruction surgery in rabbits, participated in the histological analysis and drafted the manuscript. Xiaoqing Hu designed of the study, performed the statistical analysis and carried out the micro-CT scanning. Jiahao Zhang participated in the histological analysis and measured the cross-sectional areas and diameters of bone tunnels. Weili Shi also measured the cross-sectional areas and diameters of bone tunnels and participated in the micro-CT analysis. Bo Ren did the biomechanical tests of specimens. Hongjie Huang participated in the calculation of the areas and diameters of bone tunnels. Yingfang Ao conceived of the study, and participated in its design and coordination and helped to draft the manuscript. All authors read and approved the final manuscript.
No external funding was used.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants performed by any of the authors.
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