Knee osteoarthritis (OA) is currently evaluated clinically using structural imaging. Meaningful change in biomechanical gait variables has been strongly associated with disease progression in knee OA, which can help to advance the understanding of this disease progression. Measurement of gait biomechanics is often performed in laboratories using optical motion capture systems and floor mounted force plates. However, these systems are expensive, not conveniently portable and require skilled staff to operate. Here we describe the development and testing of an alternative approach, a portable biomechanical sensor platform (BSP). The BSP consists of wireless body-worn inertial monitoring units (IMUs) and foot pressure insole units (ISUs), suitable for the measurement of lower extremity gait biomechanics. Appropriate verification and validation is a prerequisite when considering deployment of the BSP for the measurement of gait biomechanics for use as clinical trial endpoints.