I had left shoulder chondroplasty and subacromial decompression in July. In September I Backpacked for 3 days in RMNP with a Kelty Trekker pack.

45lb pack weight didn't bother me to carry but was painful and clumsy to put on. Also sleeping was uncomfortable even on a 1.5" Thermarest Prolite Plus.

I would suggest before surgery that you practice putting on your loaded pack without using your left shoulder much. I wish I had.