Limiting the angle of a joint at initiation in SimMechanics

I'm making a 2D model of a human right arm viewed from above (see attached). I'm using this model to calculate the position of limbs when given simulated hand trajectories. I use a rotational hard stop block at the shoulder to prevent the upperarm block from rotating too far counter-clockwise (stop at 90deg). However, when starting the simulation, the shoulder joint is initiated way past my hard stop (initial shoulder angle reads 145deg).

How do I set the model so that my angle constraint is respected when determining initial position of the arm.