Department of Information Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy.
Sensors (Basel). 2022 Aug 4;22(15):5815. doi: 10.3390/s22155815.
Every year in Europe more than 500 thousand injuries that involve the anterior cruciate ligament (ACL) are diagnosed. The ACL is one of the main restraints within the human knee, focused on stabilizing the joint and controlling the relative movement between the tibia and femur under mechanical stress (i.e., laxity). Ligament laxity measurement is clinically valuable for diagnosing ACL injury and comparing possible outcomes of surgical procedures. In general, knee laxity assessment is manually performed and provides information to clinicians which is mainly subjective. Only recently quantitative assessment of knee laxity through instrumental approaches has been introduced and become a fundamental asset in clinical practice. However, the current solutions provide only partial information about either static or dynamic laxity. To support a multiparametric approach using a single device, an innovative smart knee brace for knee laxity evaluation was developed. Equipped with stretchable strain sensors and inertial measurement units (IMUs), the wearable system was designed to provide quantitative information concerning the drawer, Lachman, and pivot shift tests. We specifically characterized IMUs by using a reference sensor. Applying the Bland-Altman method, the limit of agreement was found to be less than 0.06 m/s for the accelerometer, 0.06 rad/s for the gyroscope and 0.08 μT for the magnetometer. By using an appropriate characterizing setup, the average gauge factor of the three strain sensors was 2.169. Finally, we realized a pilot study to compare the outcomes with a marker-based optoelectronic stereophotogrammetric system to verify the validity of the designed system. The preliminary findings for the capability of the system to discriminate possible ACL lesions are encouraging; in fact, the smart brace could be an effective support for an objective and quantitative diagnosis of ACL tear by supporting the simultaneous assessment of both rotational and translational laxity. To obtain reliable information about the real effectiveness of the system, further clinical validation is necessary.
每年在欧洲有超过 50 万例涉及前交叉韧带（ACL）的损伤被诊断出来。ACL 是人体膝关节的主要约束之一，专注于稳定关节并控制胫骨和股骨在机械应力下（即松弛）的相对运动。韧带松弛度的测量对于诊断 ACL 损伤和比较手术结果具有重要的临床价值。通常，膝关节松弛度评估是手动进行的，为临床医生提供的主要是主观信息。直到最近，通过仪器方法对膝关节松弛度的定量评估才被引入，并成为临床实践中的重要资产。然而，目前的解决方案仅提供了静态或动态松弛度的部分信息。为了支持使用单个设备进行多参数评估，开发了一种用于评估膝关节松弛度的创新型智能膝关节支具。这款可穿戴系统配备了可拉伸应变传感器和惯性测量单元（IMU），旨在提供有关抽屉试验、lachman 试验和枢轴转移试验的定量信息。我们特别使用参考传感器对 IMU 进行了特征描述。通过应用 Bland-Altman 方法，发现加速度计的协议界限小于 0.06 m/s，陀螺仪为 0.06 rad/s，磁力计为 0.08 μT。通过使用适当的特征化设置，三个应变传感器的平均应变系数为 2.169。最后，我们进行了一项初步研究，以使用基于标记的光电立体摄影测量系统比较结果，以验证设计系统的有效性。系统区分可能的 ACL 损伤的能力的初步发现令人鼓舞；实际上，智能支具可以通过同时评估旋转和平移松弛度，为 ACL 撕裂的客观和定量诊断提供有效支持。为了获得有关系统实际有效性的可靠信息，需要进一步的临床验证。
