This study will investigate the concurrent validity and intra-rater reliability of using smartphone in assessing joint position sense in patient with knee osteoarthritis.

Knee osteoarthritis is the most common arthritis. Such disease is complicated by many musculoskeletal dysfunction such as disturbed joint position sense, which impairs their ability to perform their regular daily activities. As rehabilitation should target impairment in function, it is essential that therapists assess joint sense during baseline and follow-up evaluation of patients to decide on needed therapeutic interventions. Joint position sense can be assessed by various methods such as motion tracking systems and the isokinetic dynamometer, yet these equipment are expensive and are not readily available at regular clinical settings.

Smartphone has been introduced as an assessment tool in rehabilitation of musculoskeletal disorders. For the knee joint, smartphone has been validated for measuring range of motion and joint position sense in healthy population, yet it has never been validated in patients with knee osteoarthritis. Therefore, this study will investigate smartphone validity and reliability as an assessment tool of knee position sense in patients with knee osteoarthritis.

Inclusion Criteria:

• Patient must be referred to the outpatient clinic of the faculty of Physical Therapy and Medicine, Cairo University with a confirmed diagnosis of unilateral or bilateral osteoarthritis of the knee and having one or more of the following criteria (ASo, 2000).
• Morning stiffness for less than 30 minutes.
• Crepitus on active knee movement.
• Bony enlargement either palpable or visible in radiographs.
• Bony tenderness at joint margins.
• Age 40-60 years old.

Exclusion Criteria:

• Steroid injection within 2 months prior to inclusion.
• Presence of neurologic disorders (e.g., stroke, Parkinson's disease, or poliomyelitis). •Presence of other rheumatoid or orthopedic disorders in the lower extremity or spine. •A recent history of a lower extremity fracture with in the past year.
• History of ligament deficiency, such as anterior cruciate ligament or meniscal injury.
• Severe pain with active movement.
• Poor memory or cognitive function.

Subjects between 40 to 60 years old with symptomatic knee osteoarthritis and age-matched healthy control.

Individual participant data for all primary and secondary outcome measures will be made available.

Data will be available within 6 months of study completion.

Data access requests will be reviewed by an external independent review panel. Requestors will be required to sign a data access agreement.