Hi Debbie. Every client/patient is different, and much of how we approach their pre-op training depends on their condition when they come to us. That being said, without knowing much of the specifics of your client, I like using isometric leg lifts (seated on the floor) as a good quad strengthener that does NOT involve bending the knees.
I hope that this helps.
core muscles all the way down to the muscles of the foot should be trained. THE MUSCLES OF THE KNEE ITSELF SHOULD BE TRAINED. HOWEVER THE QUADRICEP SHOULD BE TRAINED IN A FASHION THAT DOES NOT REQUIRE KNEE FLEXION. SUCH AS STRAIGHT LEG LIFTS IN A SEATED POSITION. LEG CURLS FOR THE HAMSTRINGS USUALLY DO NOT DAMAGE THE KNEE AND CAN BE USED IF THE CLIENT FEELS NO PAIN. THE CALFS SHOULD BE CONDITIONED IN A SEATED POSITION SUCH AS SEATED CALF LIFTS, THE ANTERIOR TIB. SHOULD ALSO BE TRAINED. ADDUCTORS SHOULD BE TRAINED AS THE PLAY A BIG ROLE IN KNEE STABILITY. I USUALLY TRAIN CLIIENT IN SEATED POSITION WITH A BALL TO SQUEEZE BETWEEN LEGS. HIP EXERCISES SHOULD BE DONE SUCH AS LATERAL RAISES WITH THE LEG AND SO ON. AFTER WORK WITH REHAB FIRST. THEN SAME EXERCISES CAN BE STARTED FROM THERE. AFTER SURGERY A CLIENTS GAIT CAN BE ALTERED SO IT IS IMPORTANT TO CONDITION ALL MUSCLES INVOLVED. ALSO INCLUDE LOWER BACK EXERCISES SUCH AS PELVIC TILTS. PLEASE EXCUSE MY SPELLING AS I AM RUSHING RIGHT NOW. HOW THIS HELPS.
a client facing a knee replacement surgery has usually very limited abilities, and many exercises may be painful for this person. My go-to exercise for knee problems, including pre-op and post-rehab knee replacements, is the terminal knee extension. There are several examples on Youtube, and here is a link to one of them http://www.youtube.com/watch?v=_E3gCSdkEz0
Good luck with your client.