Help after back surgery

After many years of back pain,  my Husband had back surgery!  Was told surgery would be approx. 41/2 hrs. He would be relieved from his pain immediately,  except where the incision was!  He was in over 10+ hours!  He had L4-S1 posterior spinal decompression, posterior spinal fusion with instrumentation, Posterior lumbar interbody fusion L5-S1 for Isthmic spondylolisthesis with lumbar stenosis?  Many things happened like Rhabdomyolysis which caused many other complications, Had blood clot go to left lung, phenmonia. He was in ICU two weeks, reg. room for 5 days and rehab hospital for 3 weeks.  Worse part, he can't feel and has no control of left quad and can't walk without a brace that locks his knee from colapsing, Without this he's on the ground. Not good considering he is 6'7" about 280lbs. He has been in absolute terrible pain from this.  They were hoping it was femoral nerve palsey and would improve. It hasn't. He went today for EMG and it doesn't sound very good. Findings suggest diffuse involements of muscles innervated by left femoral nerve, peripheral nerves and radicular nerve with involement of the paraspinals!  Can someone please help us with this nightmare?  Any suggestions of what can be done, can this be fixed?  He was independent and way better off before having this surgery! HELP US UNDERSTAND WHY THIS HAPPENED?