Pastor Marc-Frederic, Kraemer Manuel, Schwarze Michael, Hurschler Christof, Smith Tomas, Wellmann Mathias
Department of Orthopaedic Surgery, Medical School Hannover, Anna-von-Borries Straße 1-7, 30625, Hannover, Germany.
Laboratory of Biomechanics and Biomaterials, Medical School Hannover, Hannover, Germany.
Arch Orthop Trauma Surg. 2018 Feb;138(2):219-225. doi: 10.1007/s00402-017-2823-7. Epub 2017 Oct 27.
Rotator cuff tears are common and good-to-excellent clinical outcome is reported after subsequent repair. However, the retear rate of rotator cuff repairs has been shown to be as high as 20%. The reasons for retear seem to be multifactorial, mainly comprised by mechanical and biological aspects. Regarding mechanical causes, the role of the tendon tension and malreduction is so far unknown. First, we hypothesized that the tendon tension depends on the technique of tendon reposition and that malreduction of the tendon results in an increased tendon tension. Second, we aimed to demonstrate the inter- and intraobserver reliability of a novel custom-made digital tensiometer clamp.
A tendon defect of posterosuperior rotator cuff (reverse L-shaped) was simulated in seven cadaveric human shoulder specimens. By use of a custom-made tensiometer clamp, the supraspinatus tendon was reduced by pulling it in (1) an anterolateral direction (anatomical reduction) and (2) in a straight lateral direction (malreduction) until the footprint was completely covered. The reduction procedure was consecutively repeated to evaluate the inter- and intraobserver reliability.
The mean traction forces for anatomical reduction and malreduction were 16.02 N (SD 8.06) and 19.52 N (SD 9.95), respectively. The difference between the two groups was statistically significant (p = 0.028). The interobserver reliability showed a correlation of r = 0.757 [95% confidence interval (CI) 0.092-0.955]. The intraobserver reliability of the three surgeons was observed to be between r = 0.905 and 0.986.
The malreduction of the rotator cuff has a significant influence on the tendon tension and may therefore affect the healing rate of the tendon after the repair, so that a tension-balanced repair could improve the clinical results. Furthermore, the application of a novel custom-made tensiometer clamp showed good interobserver and excellent intraobserver reliabilities.
肩袖撕裂很常见，后续修复后报告的临床结果良好至优异。然而，肩袖修复的再撕裂率已显示高达20%。再撕裂的原因似乎是多因素的，主要包括机械和生物学方面。关于机械原因，肌腱张力和复位不良的作用目前尚不清楚。首先，我们假设肌腱张力取决于肌腱重新定位的技术，并且肌腱复位不良会导致肌腱张力增加。其次，我们旨在证明一种新型定制数字张力计夹钳在观察者间和观察者内的可靠性。
在七个尸体人肩标本中模拟后上肩袖（反向L形）的肌腱缺损。使用定制的张力计夹钳，通过将冈上肌腱向（1）前外侧方向（解剖复位）和（2）直接外侧方向（复位不良）牵拉，直到足迹完全覆盖，来进行复位。连续重复复位过程以评估观察者间和观察者内的可靠性。
解剖复位和复位不良的平均牵引力分别为16.02 N（标准差8.06）和19.52 N（标准差9.95）。两组之间的差异具有统计学意义（p = 0.028）。观察者间可靠性显示相关性r = 0.757 [95%置信区间（CI）0.092 - 0.955]。观察到三位外科医生的观察者内可靠性在r = 0.905至0.986之间。
肩袖复位不良对肌腱张力有显著影响，因此可能影响修复后肌腱的愈合率，从而张力平衡修复可能改善临床结果。此外，新型定制张力计夹钳的应用显示出良好的观察者间可靠性和优异的观察者内可靠性。
