I have spent weeks developing his leg strength using many unilateral movements, but I now want to incorporate more bi-lateral, compound movements to further develop his strength and mobility. Are there any exercises I should steer clear of?
As stated above definitely get clearance from your Doctor or PT. I have had a knee replacement myself and have found that Kneeling exercises are not comfortable and are ill advised by my Doctor as well as Running. Good Luck with your recovery it sounds like you are doing well!