A total of 35,596 patients from Medicare and 47,064 from United Healthcare underwent TKA from 2009 to 2011. In the 2-year period before TKA, the per patient average charge was $3545.82 for Medicare and $3281.57 for United Healthcare. In the 2-year period before TKA, 21.4% (Medicare) and 23.3% (United Healthcare) of all patients received a magnetic resonance imaging, with between 31.9% (Medicare) and 45.6% (United Healthcare) of these occurring within 3 months of surgery (P < .05). During this same period, 49.4% (Medicare) and 63.2% (United Healthcare) of all patients received an intra-articular injection, with between 29.4% (Medicare) and 44.8% (United Healthcare) of these occurring within 3 months of surgery (P < .05).