Background
Knee disorders account for a large portion of the orthopedic visits to primary care practitioners, musculoskeletal physicians, and physical therapists. While some of these disorders are preceded by a single traumatic event, more than often they are attributed to biomechanical dysfunctions. In fact, the develop-ment of high prevalence knee conditions such as anterior knee pain, knee osteoarthritis, and patellar tendonitis are directly related to abnormal loading and joint mechanics (e.g. valgus collapse, varus thrust, flexion contracture). Even traumatic injuries, such as anterior cruciate ligament tears, are known to more likely occur in athletes with biomechanical dysfunc-tions. Given the association between biomechanics and joint disorders (i.e. ‘biomechanical dysfunction’), clinical practice guidelines and literature consensus recommend an accurate assessment of the gait, knee alignment and mechanical symp-toms to (i) identify the mechanism behind the pain of orthopedic knee pathologies or the mechanical changes after knee injury, and (ii) to provide the right care plan.
Tech Overview
A medical device that quickly assesses and quantifies knee joint motion in the sagittal (flexion and extension), frontal (varus and valgus), and transverse (internal and external rotation) planes while the patient is walking on a conventional/commercial treadmill. The exam starts with the in-stallation of an exoskeleton that is fixed on the boney landmarks of the patient’s knee. A brief calibration process is conducted, allowing the software to convert the position of the markers in global space, into anatomically meaningful movements. Joint centers of the knee and hip are calculated from anatomical landmarks, which are identified with a rigid wand with markers. In addition, functional movements are used to refine the centroid of the lower extremity joints, which increases the accuracy of joint rotations relative to anatomical structures.
Advantages
COMPARATIVE OUTCOMES TO X-RAY
Conventionally, a clinician would evaluate a patient’s lower limb alignment using only Hip-Knee-Ankle (‘HKA’) angles obtained during standing X-rays. However, a recent study found notable discrepancies between static X-ray alignment and dynamic alignment when walking. Nearly one-quarter of individuals who were identified as either varus or valgus alignment based on static X-rays actually displayed the opposite frontal plane limb alignment dynamically, suggesting that static radiographic images do not capture dynamic alignment.
A dynamic knee scan used to examine the loaded knee during gait as recommended by guidelines