Adams Mackenzie K, Lescun Timothy B, Mechem Alexis S, Johnson Whitney R, Griffin T Hall, Main Russell P
Am J Vet Res. 2017 Oct;78(10):1200-1209. doi: 10.2460/ajvr.78.10.1200.
OBJECTIVE To compare heat generation and mechanical bone damage for tapered and cylindrical transfixation pins during drilling, tapping, and pin insertion in equine third metacarpal bones. SAMPLE 16 pairs of cadaveric equine third metacarpal bones. PROCEDURES For cylindrical pin insertion, a 6.2-mm hole was drilled and tapped with a cylindrical tap, and then a standard 6.3-mm pin was inserted. For tapered pin insertion, a 6.0-mm hole was drilled, reamed with a tapered reamer, and tapped with a tapered tap, and then a 6.3-mm tapered pin was inserted. Paired t tests and 1-way ANOVAs were used to compare heat generation (measured by use of thermocouples and thermography), macrodamage (assessed by use of stereomicroscopy), and microdamage (assessed by examination of basic fuchsin-stained histologic specimens) between cylindrical and tapered pins and between tapered pins inserted to various insertion torques. RESULTS Tapered pin insertion generated less heat but resulted in more bone damage than did cylindrical pin insertion when pins were inserted to the same insertion torque. Insertion of tapered pins to increasing insertion torques up to 16 N•m resulted in increased heat generation and bone damage. CONCLUSIONS AND CLINICAL RELEVANCE Tapered pin insertion resulted in lower heat production than did cylindrical pin insertion. However, tapered pin insertion resulted in greater bone damage, which likely was attributable to differences in the tapered and cylindrical taps. A tapered pin may be preferable to a cylindrical pin for insertion in equine cortical bone provided that improvements in tap design can reduce bone damage during insertion.
目的 比较锥形和圆柱形固定针在马第三掌骨钻孔、攻丝和插针过程中的产热及对骨的机械损伤。样本 16 对马尸体的第三掌骨。方法 对于插入圆柱形针，先用圆柱形丝锥钻出并攻丝一个 6.2 毫米的孔，然后插入一根标准的 6.3 毫米针。对于插入锥形针，先钻一个 6.0 毫米的孔，用锥形铰刀扩孔，再用锥形丝锥攻丝，然后插入一根 6.3 毫米的锥形针。采用配对 t 检验和单因素方差分析来比较圆柱形和锥形针之间以及插入不同扭矩的锥形针之间的产热（通过热电偶和热成像测量）、宏观损伤（通过体视显微镜评估）和微观损伤（通过检查碱性品红染色的组织学标本评估）。结果 当以相同的插入扭矩插入针时，插入锥形针产生的热量较少，但导致的骨损伤比插入圆柱形针更多。将锥形针插入扭矩增加至 16 N•m 时，产热和骨损伤均增加。结论及临床意义 插入锥形针比插入圆柱形针产生的热量更低。然而，插入锥形针导致的骨损伤更大，这可能归因于锥形丝锥和圆柱形丝锥的差异。如果改进丝锥设计可以减少插入过程中的骨损伤，那么在马皮质骨中插入时，锥形针可能比圆柱形针更可取。
