Wetzler M J, Bartolozzi A R, Gillespie M J, Roth C A, Ciccotti M G, Snyder-Mackler L, Santare M H
Department of Orthopaedic Surgery, Thomas Jefferson University Medical Center, Rothman Institute of the Pennsylvania Hospitals, Philadelphia, USA.
Arthroscopy. 1996 Dec;12(6):687-93. doi: 10.1016/s0749-8063(96)90171-1.
Suture anchors have simplified anterior capsule labral reconstruction. During rehabilitation the shoulder goes through many repetitions of range of motion exercises. These exercises will repetitively submaximally load the anchor and in theory should reduce the pullout strength of the suture anchor. No published reports exist on the fatigue strengths and properties of one of the most commonly used anchors: Mitek GII suture anchors. Fifty trials of cyclic submaximal load were done on 22 cadaveric glenoids with an average age of 66.8 years (range, 40 to 90 years). At two to three different sites on the same specimen, the anchors were inserted according to manufacturer's specifications. The anchors were tested to failure on a Instron 1331 servohydraulic mechanical testing system at 2 Hertz sinusoidal loading pattern using steel sutures and a predetermined load. There were 22 (44%) tests performed in the superior quadrant and 28 (56%) tests in the inferior quadrant. All anchors pulled out, and no wires broke. There were statistically significant differences between the superior and inferior portion of the glenoid with regard to number of cycles to failure at a given maximum load. The anchors underwent an average of 6,220 cycles before pullout at an average load of 162 N (SD = 73 N). In the superior quadrant, the average ultimate pullout strength was 237 N (SD = 42 N), whereas in the inferior quadrant the average ultimate pullout strength was 126 N (SD = 36 N). Hence, the ultimate pullout strength of the Mitek GII anchor was significantly higher (P < .002) in the superior quadrant than in the inferior quadrant. Using a least squares regression analysis, it was possible to predict the fatigue life of the superiorly and inferiorly placed suture anchors over a wide range of cycles. The R-squared values for trendlines showed good reliability (superior R2 = 0.55; inferior R2 = 0.28). The fatigue life curves for the two different quadrants were normalized using the ultimate pullout strength. This new, universal curve predicts the fatigue life of the Mitek GII anchor as a percentage of the ultimate pullout strength for any selected location. For a clinically relevant number of cycles, no more than approximately 40% to 50% of the ultimate pullout strength of the suture anchor can be cyclically applied to the anchor to guarantee a life for the duration of rehabilitation. For the entire system, the inferiorly placed anchors dictate the amount of cyclically applied load the system can experience without failing, and rehabilitation should be adjusted accordingly.
缝合锚钉简化了前囊盂唇重建手术。在康复过程中，肩部要进行多次重复的活动度练习。这些练习会反复对锚钉施加次最大负荷，理论上会降低缝合锚钉的拔出强度。目前尚无关于最常用的锚钉之一——Mitek GII缝合锚钉的疲劳强度和特性的公开报告。对22个平均年龄为66.8岁（范围40至90岁）的尸体肩胛盂进行了50次周期性次最大负荷试验。在同一样本的两到三个不同部位，按照制造商的规格插入锚钉。使用钢缝线和预定负荷，在Instron 1331伺服液压机械测试系统上以2赫兹的正弦加载模式对锚钉进行直至失效的测试。在上象限进行了22次（44%）测试，在下象限进行了28次（56%）测试。所有锚钉均拔出，且没有钢丝断裂。在给定最大负荷下，肩胛盂上半部分和下半部分在失效循环次数方面存在统计学显著差异。锚钉在平均负荷162 N（标准差 = 73 N）下平均经过6220次循环后拔出。在上象限，平均极限拔出强度为237 N（标准差 = 42 N），而在下象限，平均极限拔出强度为126 N（标准差 = 36 N）。因此，Mitek GII锚钉在上象限的极限拔出强度显著高于下象限（P < .002）。使用最小二乘回归分析，可以在很宽的循环范围内预测上、下放置的缝合锚钉的疲劳寿命。趋势线的R平方值显示出良好的可靠性（上象限R2 = 0.55；下象限R2 = 0.28）。使用极限拔出强度对两个不同象限的疲劳寿命曲线进行归一化。这条新的通用曲线可以预测Mitek GII锚钉在任何选定位置作为极限拔出强度百分比的疲劳寿命。对于临床上相关的循环次数，为保证在康复期间的使用寿命，对缝合锚钉施加的循环负荷不应超过其极限拔出强度的约40%至50%。对于整个系统，下置的锚钉决定了系统在不失效的情况下能够承受的循环负荷量，康复方案应据此进行调整。
