Watt B C, Edwards R B, Markel M D, McCabe R, Wilson D G
Comparative Orthopaedic Research Laboratory, Department of Surgical and Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, USA.
Vet Surg. 2001 May-Jun;30(3):287-94. doi: 10.1053/jvet.2001.23353.
To compare the biomechanical characteristics and mode of failure of 2 parallel-screw techniques for proximal interphalangeal joint arthrodesis in horses.
Randomized block design, blocking for horse (1-5), method of screw fixation (three 4.5-mm vs two 5.5-mm), side (left limb vs right limb), and end (front limb vs hind limb). Constructs were loaded to failure in 3-point bending in a dorsal-to-palmar (plantar) direction.
Twenty limbs (10 limb pairs) from 5 equine cadavers.
A combined aiming device was used to facilitate consistent screw placement. Three parallel 4.5-mm cortical screws were placed in lag fashion in 1 limb of a pair, and 2 parallel 5.5-mm cortical screws were placed in lag fashion in the contralateral limb. Arthrodesis constructs were tested in 3-point bending in a dorsal-to-palmar (plantar) direction using a materials-testing machine. Loading rate was 19 mm/s. Maximal bending moment at failure and composite stiffness were obtained from bending moment-angular deformation curves. Data were analyzed using ANOVA and chi(2) analysis.
There were no significant differences in bending moment (P >.05, power = 0.8 @ delta = 19%) or composite stiffness (P >.05, power = 0.8 @ delta = 19%) between the 2 fixation techniques. Higher maximal bending moment was found in front limbs than hind limbs, and front limbs with two 5.5-mm screws than hind limbs with two 5.5-mm screws. In all cases, constructs completely failed. A greater number of 4.5-mm cortical screws failed than 5.5-mm cortical screws. CONCLUSIONS-In pastern arthrodesis constructs loaded in 3-point bending, end (front limb vs hind limb) affected maximal bending moment at failure of constructs. There was no significant effect of horse, treatment, or side on maximal bending moment or stiffness. Two 5.5-mm cortical screws should provide a surgically simpler pastern arthrodesis than three 4.5-mm cortical screws while maintaining similar biomechanical characteristics.
Three 4.5-mm screws or two 5.5-mm screws will provide similar biomechanical characteristics in bending when performing equine pastern arthrodesis.
比较用于马近端指间关节融合术的两种平行螺钉技术的生物力学特性和失效模式。
随机区组设计，按马（1 - 5号）、螺钉固定方法（三根4.5毫米与两根5.5毫米）、侧别（左肢与右肢）和肢体末端（前肢与后肢）进行区组。构建物在背侧至掌侧（跖侧）方向进行三点弯曲加载直至失效。
来自5具马尸体的20个肢体（10对肢体）。
使用组合瞄准装置以促进螺钉一致放置。在一对肢体的一个肢体中以拉力方式置入三根平行的4.5毫米皮质骨螺钉，在对侧肢体中以拉力方式置入两根平行的5.5毫米皮质骨螺钉。使用材料试验机在背侧至掌侧（跖侧）方向对关节融合构建物进行三点弯曲测试。加载速率为19毫米/秒。从弯矩 - 角变形曲线获得失效时的最大弯矩和复合刚度。数据使用方差分析和卡方分析进行分析。
两种固定技术在弯矩（P >.05，功效 = 0.8 @ 差值 = 19%）或复合刚度（P >.05，功效 = 0.8 @ 差值 = 19%）方面无显著差异。前肢的最大弯矩高于后肢，且前肢使用两根5.5毫米螺钉时的最大弯矩高于后肢使用两根5.5毫米螺钉时的情况。在所有情况下，构建物均完全失效。4.5毫米皮质骨螺钉失效的数量多于5.5毫米皮质骨螺钉。结论——在进行三点弯曲加载的跗关节融合构建物中，肢体末端（前肢与后肢）影响构建物失效时的最大弯矩。马、治疗方法或侧别对最大弯矩或刚度无显著影响。两根5.5毫米皮质骨螺钉在保持相似生物力学特性的同时，应比三根4.5毫米皮质骨螺钉提供手术操作更简便的跗关节融合术。
在进行马跗关节融合术时，三根4.5毫米螺钉或两根5.5毫米螺钉在弯曲时将提供相似的生物力学特性。
