Hi There,
i've seen many patients with this sensation. It takes at least 8 weeks to heal from a TKR. it's violent surgery! The tightness is generally due to swelling in the joint which does settle over time, but is exacerbated by lack of quads strength. Try a tubigrip bandage for daytimes ONLY (do NOT sleep with it on or allow it to roll up and torniquet) which can provide some comfort and light compression during mobilisation. Also quads - strengthen HEAPS.... step ups, step downs (hard if not enough eccentric control), SLR, IRQ, mini squats on one leg etc etc. Push ROM by getting the patient to sit on a chair, ask them to pull their foot in under neath actively as far as possible (ie. in your patient 70-80 degrees), then ask them to cross their good ankle in front of the operated ankle, and use the good leg to push back further and increase the knee flexion (make sure they keep their bottom firmly on the seat), then - and this will hurt and will break a sweat- keep the foot anchored and ask them to move their bottom an inch forwards on the seat to really push the flexion. they need to maintain this position for at least 2 minutes to elicit muscle elongation (not just short term elastic stretch) and then release gently. repeat 3-4 times and do this 6-7 times during the day. it is NOT fun.

the rule of 6's is true for TKR - the first 6 days are hell, the first 6 weeks are hard work, and after 6 months you don't know you've had it done (assuming you got the rehab right etc). Do the hard work now and by 12/52 your patient should feel better and more confident.

good luck
msk 101