A Deep Vein Thrombosis (DVT - basically a clot) could be a very serious condition if unrecognized. In our clinic we recently had an instance of a patient (4 weeks post-op) presenting with a few signs of this possibility and we referred him back to his MD to check it out and it turned out he had 3 small DVT's.
In the November 2008 issue of NAJSPT in an article titled "Multiple Ligament Knee Injury: Complications" there is a very clinically relevant decision rule that we have posted in our clinic as a constant reminder to look out for this complication. The original Clinical Decision Rule was actually developed in this citation:
Just as I think everyone, medical personnel and lay people, should be certified in CPR, the detection of DVT should be a critical skill that anyone exposed to a post-operative patient should have. So here are the clinical findings to look for. Each is a point towards the decision rule score, except for the last one which subtracts 2points from the score.
-advanced cancer (w/in 6 mo's of Dx or palliative care) -paralysis, paresis, or recent plaster immobilization of lower extremity (LE) -recently bedridden >3 days or major Sx w/4 wks of application of clinical decision rule -localized tenderness along distribution of the deep venous system -entire LE swelling -calf swelling >3cm compared to asymptomatic LE - pitting edema (>in symptomatic LE) -collateral superficial veins (nonvaricose) -alternative Dx as likely, or > than DVT = -2
Total of Above Score High probability >3 Moderate probability 1 or 2 Low probability
Here is a very similar version of this toward the bottom with different references (that came out in 1998 one year after the release of the one I reference, odd to me).