Orthopaedic Research Unit, Hospital Unit West, Laegaardvej 12, 7500, Holstebro, Denmark.
Knee Surg Sports Traumatol Arthrosc. 2011 Mar;19(3):355-62. doi: 10.1007/s00167-010-1205-2. Epub 2010 Aug 3.
Several devices for measuring knee laxity following anterior cruciate ligament ACL reconstruction exist, but the precision of the methods has never been optimal. Therefore, a new standardized protocol (NSP) was made, aiming at ensuring a reliable positioning of the Telos Stress Device (TSD) which theoretically could result in precise knee laxity measurements when using radiostereometric analysis (RSA) in combination with TSD.
The TSD was applied to the knee of 30 healthy persons, using both the NSP and the official company instructions. The position of the stress arms of the TSD was marked following each measurement. The reliability of each protocol was calculated as the difference in length between the first and second markings. The NSP for the TSD was then used in a clinical study. Thirty-five patients underwent ACL reconstruction. Double measurements of knee laxity by RSA were performed at a 3-month follow-up.
Using the NSP for TSD positioning, the prediction interval at the marking sites ranged from ±0.4 to ±1.1 mm. Following the company instructions, the prediction interval ranged from ±0.8 to ±3.9 mm depending on marking site. Thus, the precision of positioning the stress arms of the TSD was improved at all marking sites using the NSP compared with the original company protocol. The double measurements of the knee laxity in the clinical study resulted in a mean difference of 0.0 mm and a prediction interval of ±5.2 mm.
Even though the NSP improved the positioning of the TSD on patients' extremities, the combination of NSP-TSD and RSA was not able to provide acceptable knee laxity measurements in a clinical setting compared with published precision data for other devices on the market. Therefore, the Telos Stress Device is not recommendable for use in knee laxity measurements following ACL reconstruction.
有几种用于测量前交叉韧带（ACL）重建后膝关节松弛度的设备，但这些方法的精度从未达到最佳。因此，制定了一种新的标准化方案（NSP），旨在确保 Telos 压力设备（TSD）的可靠定位，理论上在使用放射立体分析（RSA）结合 TSD 时可以进行精确的膝关节松弛度测量。
30 名健康人使用 NSP 和官方公司说明对 TSD 施加于膝关节。每次测量后标记 TSD 应力臂的位置。每个方案的可靠性计算为第一次和第二次标记之间的长度差异。然后，在临床研究中使用 TSD 的 NSP。35 例 ACL 重建患者接受治疗。在 3 个月的随访中，通过 RSA 进行两次膝关节松弛度测量。
使用 TSD 定位的 NSP，标记部位的预测间隔范围为±0.4 至±1.1mm。根据公司的说明，预测间隔范围从±0.8 到±3.9mm，具体取决于标记部位。因此，与原始公司方案相比，使用 NSP 可提高 TSD 应力臂在所有标记部位的定位精度。临床研究中的膝关节松弛度双测量结果为 0.0mm 的平均差异和±5.2mm 的预测间隔。
尽管 NSP 改善了 TSD 在患者肢体上的定位，但与市场上其他设备的已发表精度数据相比，NSP-TSD 和 RSA 的组合无法在临床环境中提供可接受的膝关节松弛度测量。因此，Telos 压力设备不推荐用于 ACL 重建后膝关节松弛度的测量。
