For the smart phone analysis we will be using the tilt meter application which is a digital inclinometer application available on the I phone. The phone will be placed in the vertical position utilizing the bubble level feature of the application. The application will be set to display measurements to the closest tenth of the degree, set to log measurements every 0.2 seconds. The subject will stand with knee extended to 0 degrees and quadriceps muscle activated and upper extremity support on opposite side of stance limb. The phone will be placed in the vertical position on the anterior portion of the middle third of the subject's thigh attached using double sided adhesive tape. Being placed as close as possible to level when attached to the anterior thigh with subject in single limb stance with a reading of less than 1 deg as minimum for correct set-up prior to testing. Immediately prior to testing recording will be initiated logging measurements for later assessment.

two dimensional video analysis by first placing markers on the subject at the midpoint of the femoral condyles, midpoint of the ankle malleoli, and the proximal thigh along a line from the anterior superior iliac spine (ASIS) to the knee marker. Testing will take place in front of a digital video camera with tape on the floor to give a reference point for the subject being tested. Participants will be tested twice on day 1 and then again 5-9 days later. Subjects will be allowed 2-3 practice trials prior to each test in order to allow the subject to feel comfortable with each test. Following the practice trials the subject will perform 3 trials of each test on bilateral lower extremities. This set up was consistent with the set up by Munro et al.

Patient's dynamic lower extremity valgus during single leg squat will be measured using both 2-D video analysis and smart phone inclinometer analysis. Measurements of 2-D and smart phone will be taken at the same time. Analysis will be repeated at 2nd visit to assess the reliability of the measurements

Patient's dynamic lower extremity valgus during a drop jump from a 12 inch step will be measured using both 2-D video analysis and smart phone inclinometer analysis. Measurements of 2-D and smart phone will be taken at the same time. Analysis will be repeated at 2nd visit to assess the reliability of the measurements

Patient's dynamic lower extremity valgus during a single leg drop jump from a 12 inch step will be measured using both 2-D video analysis and smart phone inclinometer analysis. Measurements of 2-D and smart phone will be taken at the same time. Analysis will be repeated at 2nd visit to assess the reliability of the measurements