An experiment was performed to study the load bearing function of a patellar tendon bearing (PTB) cast and the optimal effect of walking heel position and contra-lateral heel height. Miniature load cells were placed on the patellar tendon area, front and back area of the lower leg, anterior sole (MP joint of big toe), and posterior sole of the foot. The examinee walked on a force plate with the PTB cast. Vertical load bearing at each area in the PTB cast was evaluated by multiple regression analysis of data from the force plate and the load cells. The extent of decrease of skeletal loading was thirty per cent of body weight when the walking heel was placed slightly distal to the navicular bone. The effect of the contralateral heel height was not clear.