Brown G A, Peña F, Grøntvedt T, Labadie D, Engebretsen L
Department of Orthopaedic Surgery, University of Minnesota, Minneapolis 55455, USA.
Knee Surg Sports Traumatol Arthrosc. 1996;3(4):238-44. doi: 10.1007/BF01466626.
A failure analysis of interference screw fixation was performed to test the hypothesis that bovine and/or elderly human cadavers are appropriate models for bone-patellar tendon-bone anterior cruciate ligament (ACL) reconstruction fixation studies. Failure mode is an important criterion for validating experimental models. The bovine, young human, and elderly human failure loads were 799 +/- 261 N, 655 +/- 186 N, and 382 +/- 118 N, respectively, and the failure modes were 75%, 69%, and 30% tissue failures, respectively. The similarities between the bovine and young human models in failure loads and failure modes indicate that bovine models are appropriate for ACL reconstruction fixation studies. The statistically significant differences between the young human and elderly human models in failure loads and failure modes indicate that elderly human cadavers are not an appropriate model for ACL reconstruction fixation studies. The differences in failure modes are consistent with previous studies using elderly human cadavers in which the predominant failure mode was bone block pullout. The tissue failures observed in the bovine and young human models contradict previous studies suggesting fixation strength is the weakest link in bone-patellar tendon-bone ACL reconstruction. Results of linear regression modeling showed statistically significant correlations between insertion torque and failure load (R2 = 0.44, P < 0.0001) and interference (defined as the screw outer thread diameter minus the tunnel-bone block gap) and insertion torque (R2 = 0.18, P = 0.003) when data from all models was combined. Results for the bovine model multiple regression showed a statistically significant regression of insertion torque (linear) and interference (quadritic) versus failure load (R2 = 0.56, P = 0.02). Regression slopes for screw diameter (P = 0.52) and gap size (P = 1.00) were not statistically significant. These results indicate that insertion torque and interference are independent predictors of failure load and should be included in future interference screw studies in addition to bone block dimensions, tunnel size, gap size, and screw diameter. Clinicians may consider using insertion torque and interference as indicators of postoperative graft fixation regarding rehabilitation decisions.
对干涉螺钉固定进行了失效分析，以检验以下假设：牛和/或老年人体尸体是用于骨-髌腱-骨前交叉韧带（ACL）重建固定研究的合适模型。失效模式是验证实验模型的一个重要标准。牛、年轻人体和老年人体的失效载荷分别为799±261 N、655±186 N和382±118 N，失效模式分别为75%、69%和30%的组织失效。牛和年轻人体模型在失效载荷和失效模式上的相似性表明，牛模型适用于ACL重建固定研究。年轻人体和老年人体模型在失效载荷和失效模式上的统计学显著差异表明，老年人体尸体不是ACL重建固定研究的合适模型。失效模式的差异与先前使用老年人体尸体的研究一致，在这些研究中，主要的失效模式是骨块拔出。在牛和年轻人体模型中观察到的组织失效与先前的研究相矛盾，先前的研究表明固定强度是骨-髌腱-骨ACL重建中最薄弱的环节。线性回归模型的结果显示，当合并所有模型的数据时，插入扭矩与失效载荷之间存在统计学显著相关性（R2 = 0.44，P < 0.0001），干涉（定义为螺钉外螺纹直径减去隧道-骨块间隙）与插入扭矩之间存在统计学显著相关性（R2 = 0.18，P = 0.003）。牛模型多元回归的结果显示，插入扭矩（线性）和干涉（二次）与失效载荷之间存在统计学显著回归（R2 = 0.56，P = 0.02）。螺钉直径（P = 0.52）和间隙尺寸（P = 1.00）的回归斜率无统计学显著性。这些结果表明，插入扭矩和干涉是失效载荷的独立预测因子，除了骨块尺寸、隧道大小、间隙尺寸和螺钉直径外，还应纳入未来的干涉螺钉研究中。临床医生在做出康复决策时，可考虑将插入扭矩和干涉作为术后移植物固定的指标。
