The knee joint displays a wide spectrum of laxity, from inherently tight to excessively lax even within the normal, uninjured population. The assessment of AP knee laxity in the clinical setting is performed by manual passive tests such as the Lachman test. Non-invasive assessment based on image free navigation has been clinically validated and used to quantify mechanical alignment and coronal knee laxity in early flexion. When used on cadavers the system demonstrated good AP laxity results with flexion up to 40°. This study aimed to validate the repeatability of the assessment of anteroposterior (AP) knee joint laxity using a non-invasive image free navigation system in normal, healthy subjects.Twenty-five healthy volunteers were recruited and examined in a single centre. AP translation was measured using a non-invasive navigation system (PhysioPilot) consisting of an infrared camera, externally mounted optical trackers and computer software. Each of the volunteers had both legs examined by two Examiners twice. The Lachman test was performed through flexion in increments of 15º. Coefficients of Repeatability (CR) and Interclass Correlation Coefficients (ICC) were used to validate AP translation. The acceptable limits of agreement for this project were set at 3mm for anteroposterior tibia translation. The most reliable and repeatable AP translation assessments were at 30º and 45º, demonstrating good reliability (ICC 0.82, 0.82) and good repeatability (CR 2.5, 2.9). The AP translation assessment at 0º, 15º, 75º and 90º demonstrated poor reliability (ICC ≤ 0.75), and poor repeatability (CR ≥3.0mm).The non-invasive system was able to reliably and consistently measure AP knee translation between 30° and 45° flexion, the clinically relevant range for this assessment. This system still requires further validation in-vivo prior to its use in a clinic setting to quantify abnormal knee laxity and improve the assessment of knee instability and ligamentous injuries.
|Date of Award||1 Dec 2014|
- University Of Strathclyde
|Supervisor||Philip Rowe (Supervisor) & Phil Riches (Supervisor)|