System design of a knee motion sensor to prevent ACL injuries

摘要

One of the most common traumatic sport-related injuries with potential short and long-term morbidities is the Anterior Cruciate Ligament (ACL) injury. More than 200,000 people sustain ACL injuries each year in the United States alone. Additionally, female NCAA athletes are 2 to 8 times more likely to sustain an ACL injury than male NCAA athletes. ACL injuries occur when the force on the ACL, known as the Tibial Shear Force (TSF), exceeds 2100 Newton (N). ACL injuries do not heal on their own; therefore, surgery is usually necessary. Surgical treatment can cost on average $16,000 and requires 6 to 9 months of rehabilitation. Athletes cannot feel pain when they are applying an excessive amount of strain on their ACL. As a result, they are unaware of when their TSF approaches 2100 Newton(N). A Knee Motion Sensor (KMS) has been developed to provide real-time situational awareness for athletes in a game by: (1) using inputs retrieved from sensors and converting it into usable data (2) using data along with TSF equations to calculate the strain being placed on the ACL (3) alerting the user if the TSF is approaching 2100 Newton (N) and (4) allowing the athlete to use situational awareness for a post-game analysis on which movements they are doing that may be harming their ACL. Verification testing has been completed to prove that the prototype meets the system requirements. The pressure pads exhibited an accuracy of 89.0% in the range of 2.27 kg to 80.63 kg. The flex sensor measured angles with an accuracy of 96.8% between 35° and 180°. The accelerometer was shown to measure the acceleration with an average error of 0.45 m/s. Preliminary testing demonstrated that the KMS estimated the TSF within tolerance to provide the athlete with real-time situational awareness in both game-time setting and post-game analysis.