Moss David P, Means Kenneth R, Parks Brent G, Forthman Christopher L
Curtis National Hand Center, Union Memorial Hospital, Baltimore, MD 21218, USA.
J Hand Surg Am. 2011 Dec;36(12):1907-11. doi: 10.1016/j.jhsa.2011.08.039. Epub 2011 Oct 22.
To determine whether the number of distal locking screws significantly affects stability of a cadaveric simulated distal radius fracture fixed with a volar locking plate.
We created AO/ASIF type C2 fractures in 10 matched pairs of human fresh-frozen cadaveric wrists and then fixed them using volar locking plates. The number of distal locking screws used was 4 screws or 7 screws in each wrist of the matched pair. We loaded the stabilized fractures cyclically to simulate 6 weeks of postoperative stressing during a therapy protocol and then loaded them to failure. Failure was defined as 2 mm or more of displacement of any fracture fragment as recorded by differential variable reluctance transducers.
No wrists failed during the cyclic loading portion for either the 4- or 7-screw construct. The average initial stiffness of the 7-screw construct was 69 N/mm (± 38) versus 48 N/mm (± 14) for the 4-screw construct. The average failure load for the 7-screw construct was 139 N (± 78) versus 108 N (± 18) for the 4-screw construct. Neither of these differences was statistically significant.
Although there was a trend toward increased initial stiffness and higher failure load in fractures fixed distally with 7 locking screws, the results were not statistically significant compared with fractures fixed with only 4 screws. Both constructs can withstand forces likely encountered in early therapy protocols.
The use of extra distal locking screws when fixing distal radius fractures increases expense and may increase the risk of complications, such as extensor tendon irritation or rupture.
确定远端锁定螺钉的数量是否会显著影响用掌侧锁定钢板固定的尸体模拟桡骨远端骨折的稳定性。
我们在10对匹配的人类新鲜冷冻尸体手腕上制造了AO/ASIF C2型骨折，然后用掌侧锁定钢板进行固定。在匹配对的每只手腕中，使用的远端锁定螺钉数量为4枚或7枚。我们对稳定的骨折进行循环加载，以模拟治疗方案中术后6周的应力，然后加载至骨折失效。失效定义为差分可变磁阻传感器记录的任何骨折碎片移位2毫米或更多。
对于4枚螺钉或7枚螺钉的固定结构，在循环加载部分均没有手腕发生失效。7枚螺钉固定结构的平均初始刚度为69 N/mm（±38），而4枚螺钉固定结构为48 N/mm（±14）。7枚螺钉固定结构的平均失效载荷为139 N（±78），而4枚螺钉固定结构为108 N（±18）。这些差异均无统计学意义。
尽管用7枚锁定螺钉进行远端固定的骨折在初始刚度和失效载荷方面有增加的趋势，但与仅用4枚螺钉固定的骨折相比，结果无统计学意义。两种固定结构都能承受早期治疗方案中可能遇到的力。
在固定桡骨远端骨折时使用额外的远端锁定螺钉会增加费用，并可能增加并发症的风险，如伸肌腱刺激或断裂。
