前交叉韧带生物力学止点重建的解剖学与有限元分析

目的 解剖研究大体观察膝关节前交叉韧带(anterior cruciate ligament, ACL)胫骨止点的形态,并利用有限元分析软件分析ACL的力学止点分布,为临床ACL重建提供新理念。方法 选取10例新鲜成人膝关节标本,男6例,女4例,采取标准髌旁内侧入路打开关节腔,暴露并解剖剔除ACL,观察并记录ACL胫骨止点形态,测量胫骨止点前后径和左右径。利用三维重建软件MIMICS及有限元分析软件ANSYS建立膝关节模型,模拟临床体格检查Lachman试验和pivot-shift试验,观察ACL在胫骨和股骨端止点的受力分布情况。结果 ACL胫骨致密止点大体观呈扁长的弧形,其前后径为(13.8±2.0) mm,体部左右径为(5.3±0.6) mm,前缘左右径为(11.5±1.2) mm。有限元分析显示,股骨端应力较高区域为住院医师嵴(residents’ ridge)附近一类椭圆形区域,胫骨端应力较高部分延内侧髁间嵴(medial intercondylar ridge)狭长分布,与解剖观察相符,从理论上验证了ACL止点的生物力学分布特点。结论 解剖研究及有限元分析均证实ACL胫骨止点为一扁长的弧形,理想的ACL重建技术应依据其生物力学特点进行重建, 基于解剖学研究和生物力学分析本课题组提出前交叉韧带生物力学止点重建理念,并建立手术模型。

Anatomical and finite element analysis of anterior cruciate ligament reconstruction within biomechanical insertion

Objective: To provide new concepts of anterior cruciate ligament (ACL) reconstruction by anatomical gross observation of ACL tibial insertion and finite element analysis of distribution of ACL mechanical insertion.Methods: In the anatomical study, ten fresh adult cadaveric knees were dissected, including 6 males and 4 females, all knees were generally observed through standard medial parapatellar approaches, paying attention to the close anatomical relationship of tibial insertion and anterior horn of lateral meniscus, and ACL was exposed and gradually removed from the inside. The shape of tibial insertion of ACL was observed and recorded, and anterior-posterior diameters and left-right diameters of tibial insertion were measured with vernier caliper. For the study of finite element analysis, three-dimensional thin-layer magnetic resonance imaging of normal knee joint was used to establish knee joint model. Three-dimensional reconstruction software MIMICS and finite element analysis software ANSYS were used to establish knee joint model, subsequently, clinical physical examination Lachman test and pivot-shift test were simulated to observe the force distribution of ACL tibial insertion and femoral insertion. Results: The ACL tibial mechanical insertion was rather flat and long similar as an arc shape without a clear separation between anterior medial bundle (AMB) and posterolateral bundle (PLB) in gross observation. The dense fibers lies belonged to the medial intercondylar ridge and ended up anterior with the osseous landmark of anterior ridge. Its average anterior-posterior diameter was (13.8±2.0) mm, the average left-right diameter of midsubstance was (5.3±0.6) mm, and the average left-right diameter of anterior margin was (11.5±1.2) mm. The finite element analysis showed that distribution on the femoral side was oval shape mainly below the residents’ ridge, while the tibial side was rather flat mainly along the medial intercondylar ridge, which was consistent with the anatomical observation. The biomechanical characteristics of ACL attachments were verified theoretically.Conclusion: Anatomical study and finite element analysis have confirmed the flat arc shape of ACL tibial insertion. The ideal reconstruction technique of ACL should be based on its biomechanical insertion. Based on anatomical study and biomechanical analysis, we have proposed the idea of ACL biomechanical insertion reconstruction (BIR) and established a surgical model with oval femoral tunnel and rounded-rectangle tibial tunnel.