Risk Classification for Primary Knee Arthroplasty

We devised a 4-group classification for primary TKA patients: C0, fit patient, simple arthritis; CI, fit patient, complex arthritis; CII, medically unfit patient with simple pattern; and CIII, unfit patient with complex arthritis. Patient fitness and arthritis complexity were based on the literature. One hundred twenty-two patients, operated on by the senior author, were retrospectively placed into one of these 4 groups. We found the following: significantly increasedcumulative complication risk in CII and CIII incomparison with C0 (P < .001), increased length of stay in CII and CIII (P < .001), and similar trends between C0 and CI and between CI and CII. This system is useful in preoperative planning, risk counseling, and surgeon selection. It identifies patients with a higher risk of complications and inpatient stay.