The purpose of this study is to investigate the intra- and inter-rater reliability and concurrent validity of surgimap software for measuring the Q angle Surgimap (Nemaris Inc, New York, NY, USA) is a dedicated spine measurement and surgical planning software which is used in both the research works and the clinical rehabilitation. Q angle is considered to be an index of the vector for action of the patellar tendon and extensors mechanism which is highly affects the patellofemoral joint dysfunction and foot mechanics.

specialised software for assessing the sagittal plane has arisen. Digital measuring software of many types has been proved to be faster, more accurate, more precise, and less variable than manual procedures. Angle measurement software is available in different formats and applications. Surgimap is another programme used for measuring angles. The current software has proven to be a godsend and is currently being used in the medical industry to measure joint angles especially the spine alignment. The programme is also used for scientific reasons, such as digital photo analysis. A recent study discovered that Surgimap software is a viable approach for evaluating spinal postural angles in teenagers from varied standing position perspectives using digital pictures.

As there a lack of knowledge about the reliability and validity of the surgimap software to measure the Q- angle. Therefore, The study will investigate the inter-rater, intra-rater reliability and concurrent validity of the surgimap software for measuring the Q-angle.

Inclusion Criteria:

• Both male & female
• Aged 18:25
• BMI 18.5: 25
• Normal foot posture as assessed by foot posture index.

Exclusion Criteria:

• Subjects who have operations in the knee joint
• Subjects who have traumatic knee injury
• High arched or low arched foot.

This study will be conducted in the out-patient clinic Faculty of physical therapy, Cairo University. The expected duration to recruit patients and collect data is 3 months .