For many years' physiotherapists have been using ultrasound in treatment of knee osteoarthritis especially in geriatrics (people aged above 65 years) for its known therapeutic effect in relieving pain and improving knee function. Hyaluronan is used to treat osteoarthritis of the knee. Such treatments, called viscosupplementation, are administered as a course of injections into the knee joint, and are believed to supplement the viscosity of the joint fluid, thereby lubricating the joint, cushioning the joint, and producing an analgesic effect. Studies reveals the risk for falls increases with additional symptomatic OA lower limb joints and confirms in addition to gender factor; including female sex.

It is hypothesized that physical therapy by ultrasound might add some extra benefit on risk of fall when applied after intra-articular hyaluronate of Knee OA in female geriatrics. So, forty female geriatrics with ages ranged from 65 to 75 years, randomly will be selected from Ahmed Maher Teaching Hospital, Kasr el einy hospital, Charity clinic and Outpatient clinic of Badr university, referred to physical therapy by an orthopedic surgeon. All will be diagnosed as chronic OA of one or both knees where conventional therapeutic measures failed. They will be assigned to begin HA intra-articular knee injection by the orthopedic surgeon once weekly for 3 weeks. These patients will be randomly divided into 2 groups equal in number, group (1) the study group, they will receive HA intra-articular injection in addition to 12 sessions of therapeutic ultrasound, while group (2) served as the control group receiving only HA intra-articular knee injection.

Inclusion Criteria:

• Patients' ages above 65 years.
• Patients diagnosed as chronic osteoarthritis of more than 5 years.
• The OA diagnosed as grade (III to V)
• Patients failed with conventional treatment.
• All patients followed up with the same orthopedic surgeon, and they took the same type of HA intra-articular injection (HA of High MW 3000 kDa).
• All patients were medically stable and do not suffer from any other diseases which may affect the trial results.
• All patients were not treated with analgesics or any medication which may cause misleading results.
• None of the patients received intra-articular hyaluronic acid injection for 1 year or intra-articular corticosteroid injection within the last 3 months.
• All patients didn't take or oral glucosamine or chondroitin supplements or stopped these drugs 2-3 months before participating in this study.
• Every patient signed a consent form.

Exclusion Criteria:

• Young individuals (their age is below 65 years old).
• Mild degree of OA (grade I & II).
• Patients who had undergone knee arthroscopy, or any knee surgery.
• Patients with OA secondary to trauma.
• Patients with metal implants.
• Patients with CNS dysfunction.

Females are affected more than males due to menopausal changes and declined estrogen hormone that accelerates bone loss and leads to high risk of fall and decreased balance due to orthopedic issues.