The purpose of this study is to:

1. Analyze the short-term effects of external center of pressure manipulation of the foot in idiopathic hip osteoarthritis patients during gait on:

   1. Gait parameters (spatiotemporal, kinematic, and kinetic)
   2. Muscle activation patterns of the lower limbs and back

2. Analyze the long-term effects (during the period of one year) of external center of pressure manipulation of the foot in idiopathic hip osteoarthritis patients during gait on:

   1. Gait parameters (spatiotemporal, kinematic, and kinetic)
   2. Motor learning and muscle activation patterns
   3. Energy consumption
   4. Pain, physical function, and quality of life

The hypotheses of the study, in reference to the aforementioned study objectives are:

1. Changes in foot center of pressure will have an immediate effect on gait parameters and muscle activation patterns of the lower limbs and back.
2. Long-term manipulation of foot center of pressure, as a result of a year-long rehabilitation program using the AposTherapy Biomechanical System, will result in improvement in gait parameters, changes in muscle activation patterns as a result of new motor learning, improvement in energy consumption, decrease in pain, improvement in physical function, and improvement in quality of life.

This study is a randomized prospective controlled study assessing the short and long-term effects of external foot center-of-pressure manipulation on gait pattern, muscle activation pattern, energy consumption, physical function, pain, and quality of life. Sixty patients will be recruited for the study and divided randomly into two groups, an experimental group (thirty patients) and a control group (thirty patients). Both groups will be similar with respect to demographic and pathological profiles.

The experimental group will be fitted with a customized biomechanical device worn on the feet (AposTherapy Biomechanical System, AposTherapy - Sports and Medical Technologies Ltd., Hertzlia, Israel). The device is custom calibrated for each patient. The device allows center of pressure manipulation for all phases of the gait cycle and induces controlled perturbation during gait. The immediate effects of the device will be evaluated using center of pressure measurements, three-dimensional gait analysis, and surface electromyography. Following this, patients will be instructed to walk with the device at home on a daily basis according to a customized AposTherapy therapy protocol. They will return to the laboratory for measurements of gait pattern, muscle activation pattern, energy consumption, physical function, pain, and quality of life after three months, six months, and twelve months from the start of the therapy protocol. Data from the analyses will be used to reveal potential changes in the aforementioned measurements as a result of the study intervention.

The control group will carry out the same measurements in the laboratory over the period of one year, however without the biomechanical intervention device.

Inclusion Criteria:

• Women age 50 and over with unilateral or bilateral idiopathic hip osteoarthritis

Exclusion Criteria:

• Previous surgery on the lower limbs or back
• Previous musculoskeletal injuries and/or diseases of the lower limbs or back
• Cognitive disabilities and/or inability to cooperate or understand study instructions
• Vestibular problems and/or use of a walking aid
• Neurological and/or orthopaedic and/or cardiovascular and/or pulmonary disorders or risks that may impact the patient's functional performance or limit exercise