Objective: To investigate the histological characteristics of autogenous hamstring grafts after anterior cruciate ligament (ACL) reconstruction.
Methods: The patients who underwent arthroscopic single-bundle ACL reconstruction with autogenous hamstring tendons and were followed up at least 4 years and also underwent second-look arthroscopy between March 2017 and December 2017 and met the selection criteria were considered for enrollment. Graft quality under arthroscopy was evaluated as good remodeling group (GRG, the total scores were 4-6) and poor remodeling group (PRG, the total scores were 1-3) according to synovial and vascular coverage, the apparent tension of the grafts, the thickness and retear of the grafts. During the second-look arthroscopic procedures, ACL graft biopsies were performed. Normal ACL tissues harvested from the patients under 60 years old who underwent total knee arthroplasty were designated as normal controls. Graft vascularity, cellular morphology, cellular metabolism, and collagen fibril distribution were analyzed.
Results: The 18 specimens (11 cases of GRG group and 7 cases of PRG group) and 9 native ACL biopsied tissue sample were enrolled into the study. Arthroscopy scores were 2-6 (mean, 4.7). The biology under light microscopy of GRG group was similar to that of native ACL in control group. There was no significant difference in the scores of graft vascularity and cellular morphology between GRG group and control group ( P>0.05), while PRG group was significantly lower than the other two groups ( P<0.05). Transmission electron microscope evaluation showed that GRG group and control group had better collagen fibril distribution and lower levels of cellular metabolism than PRG group ( P<0.05). There was no significant difference in cellular metabolism between GRG and control groups ( P>0.05), while collagen fibril distribution score of GRG group was significantly lower than that of control group ( P<0.05).
Conclusion: While good remodeling grafts under arthroscopy in histological maturation period was proved to be more similar to normal ACL on ultrastructure properties under light and electron microscope, ultra structural differences regarding collagen fibril distribution still persist.
目的: 观察自体腘绳肌腱移植重建前交叉韧带（anterior cruciate ligament，ACL）术后移植物组织学表现特点，总结 ACL 移植物组织学转归规律。.
方法: 以 2017 年 3 月—12 月应用自体腘绳肌腱移植单束重建 ACL 术后 4 年以上、因移除胫骨端内固定物行二次关节镜探查，并符合选择标准的患者为研究对象。根据关节镜下对移植物滑膜及血管覆盖、移植物张力、移植物容量及纤维再撕裂情况评分，将患者分为塑形良好组（good remodeling group，GRG），总分为 4～6 分；塑形不良组（poor remodeling group，PRG），总分为 1～3 分。镜下取移植物体部中央标本，分别行光镜观察（细胞形态、血管分布）及透射电镜观察（细胞合成代谢、胶原纤维分布）并评分。以同期行人工全膝关节置换术且年龄<60 岁患者的正常 ACL 标本作为对照组。.
结果: 共 18 例二次关节镜探查患者纳入研究，关节镜下移植物评分为 2～6 分，平均 4.7 分；其中 GRG 组 11 例、PRG 组 7 例。对照组 9 例。光镜下观察示，PRG 组血管分布及细胞形态评分均明显低于对照组及 GRG 组（ P<0.05）；GRG 组与对照组相关评分比较，差异无统计学意义（ P>0.05）。透射电镜观察示，PRG 组胶原纤维分布评分较对照组及 GRG 组明显降低，但细胞合成代谢评分明显增高，比较差异均有统计学意义（ P<0.05）；GRG 组细胞合成代谢评分与对照组比较差异无统计学意义（ P>0.05），但胶原纤维分布评分明显低于对照组（ P<0.05）。.
结论: ACL 重建术后自体腘绳肌腱移植物塑形稳定期，关节镜下评估为塑形良好的移植物在光镜下其组织学结构更接近于正常 ACL，但其超微结构特点与正常 ACL 仍存在明显差异。.
Keywords: Anterior cruciate ligament; graft; histology; ligamentization; ultrastructure.