 Each patient participant will complete a Norwich Patellar Instability NPI Score questionnaire, a Kujala Patellofemoral Disorders Score, a PainDetect score and a Catastrophising score which are validated questionnaires. Baseline data recorded prior to testing will include: presence of joint hypermobility syndrome Beighton score, age, gender, duration of symptoms, frequency of kneecap dislocation, knee range of motion, MRC Medical Research Council muscle strength flexion and extension, previous patellofemoral joint surgery, family history of patellar instability and whether patellar instability is unilateral or bilateral. Basic demographic data for multi-variate regression analysis e.g. Body Mass Index data will also be collected, along with measurements such as leg length height required for Hof scaling. 