Hemiarthroplasty of the knee was first described in the 1950s. It refers to the concept of placing a “spacer” in one half of the femoral tibial joint to prevent bone-on-bone apposition. McKeever (1) first introduced his Vitallium “tibial plateau” (Fig 43.5-1) in 1957. MacIntosh (2) followed with an “acrylic tibial plateau” (Fig 43.5-2) in 1958, which was followed in turn by Vitallium in 1964. MacIntosh (2) then presented his initial series in Switzerland in 1967 and published a series of patients in 1972 with “good results” in the “majority” of patients having a follow-up period of 6 years (3). The modern version of the hemiarthroplasty is the “unispacer” (Figs 43.5-3 and 43.5-4), with a reported success rate of 67% to 80% after 2 years of follow-up (4,4a).

During the early 1970s, the Gunston and polycentric unicompartmental arthroplasty (UKA) procedure was introduced (Figs 43.5-5 and 43.5-6). The revision rate at 2 years for these early devices was approximately 10% (5,6). Multiple authors from 1973 to 1983 noted success rates varying between 37% and 92% from 2 to 8 years of follow-up (5,6,7,8,9,10,11,12,13). From 1987 to 1991, long-term results were published, with 87% to 90% survivorship at 13 to 16 years of follow-up (14,15,16).

From 1990 to 1993, several authors reported 90% to 96% fair to good results using a combination of metal-backed and all-polyethylene tibial components with 2 to 7 years of follow-up (17,18,19,20,21). This was the first time that obese patients were noted to have a 1.4-fold greater failure rate (18).

Multiple survivorship studies were reported from 1993 to 2003, with success rates from 87% to 98% noted at 6 to 14 years of follow-up (22,23,24,25,26,27,28,29,30). In one series, 83% of the failures resulted from progressive wear in the unresurfaced compartment (27).