自体和异体肌腱移植重建前十字韧带后止点转归的组织学研究

Histological comparison of the fate of autograft versus allograft in anterior cruciate ligament reconstruction

目的比较自体和异体肌腱移植重建前十字韧带后韧带止点的组织学转归。方法取12只健康成年杂种犬,切除双膝前十字韧带,切取伸趾肌腱,对折成双股后移植重建前十字韧带,韧带的两端分别通过胫骨和股骨骨隧道后用缝线和螺钉固定,将每条犬的左右侧膝关节随机建成自体或异体的腱-骨愈合模型。采用HE染色,观察比较韧带重建后其止点在6周、12周、6个月时的组织学表现。结果正常犬的前十字韧带止点具有四层移行结构,即致密结缔组织、纤维软骨、钙化纤维软骨和骨组织,在纤维软骨和钙化纤维软骨之间可见清晰连续的“潮线”。术后6周,自体和异体肌腱重建韧带止点均可见韧带与骨隧道之间充满疏松结缔组织。12周时,自体韧带与骨隧道之间胶原纤维排列有序,并已形成明显的“潮线”,但不连续,四层结构不清;异体韧带与骨隧道之间胶原纤维排列无序,无明显的“潮线”形成。6个月时,自体韧带与骨隧道之间形成明显的“潮线”,且连续,四层结构清晰;异体韧带与骨隧道之间也已形成“潮线”,但“潮线”的起伏性、连续性及结构均较自体韧带差。结论无论是自体肌腱还是异体肌腱移植重建前十字韧带,6个月后均可初步形成韧带-软骨止点;但在相同时间点,自体肌腱止点的组织学形态优于异体肌腱。

Objective To compare the histological results and biological remodeling of the anterior cruciate ligament (ACL) reconstruction with autograft versus allograft tendon. Methods A double strand of tendon harvested from extensor digitorum tendon in mongrels were transplanted to reconstruct the ACL, while their original ACL was resected. Each free tendon end was fixed by sutures, and tied to post screws at both the femoral and tibial tunnel outlets after transplantation. Autograft was randomly performed in one knee and allograft in contralateral knee. The histological analysis was undertaken at the 6th week, 12th week, and 6th month after the transplantation using HE staining under light microscope. Results The insertion of normal ACL typically consisted of four zones: dense connective tissue, fibrocartilage, mineralized fibrocartilage and bony tissue. There was a distinct regular tidemark line between fibrocartilage and mineralized fibrocartilage. At the 6th week postoperatively, loose connective tissue presented into interspace of graft and bone tunnel wall in both grafts. At the 12th week postoperatively, the collagenous fibers between autograft and tunnel wall became well organized, four zones of insertion with discontinuous tidemark line was demonstrated indistinctly in autograft group but not in the allograft group. At the 6th month postoperatively, both of the clear and continuous tidemark line and distinct four zones could be seen in autograft group. In the allograft group, only a waved discontinuous tidemark line was shown and either the anatomic morphology or the maturity of insertion was inferior to the autograft group. Conclusion After 6 months of reconstruction, although the ligament-cartilage insertion is primarily formed in both of the autograft and allograft tendons, but the histological morphology and maturation of insertion of autograft tendon is better than allograft tendon, which suggest that postoperative rehabilitation should be paid more attention and could be safer if little delayed.