Perceptions of outcomes after unicompartmental and total knee replacements

An independent measurement of the quality of outcome of 31 consecutive Oxfo rd medial unicompartmental knee replacements in 28 patients and 130 total k nee replacements in 104 patients performed between 1993 and 1997 is reporte d. The indications for surgery were anteromedial osteoarthritis for unicomp artmental replacement and more extensive osteoarthritis for total knee repl acement. All patients were treated by one surgeon. As a validated outcome m easure of knee function, the Oxford 12-item knee questionnaire showed ident ical outcome in both groups with a mean score of 36.5 (maximum possible, 48 ). Neither the pain nor the functional outcomes were significantly differen t, although patients receiving unicompartmental replacement were better abl e to descend stairs. Two patients needed revision surgery in the unicompart mental replacement group compared with only one patient in the total knee r e-placement group. The femoral component of two unicompartmental replacemen ts showed radiologic signs of loosening. The tibial component of one total knee replacement appeared loose, but the patient had no symptoms. In compar ison with total knee replacement, implantation of meniscal bearing unicompa rtmental replacement technically is demanding and unforgiving. However, rev ision of a failed Oxford unicompartmental replacement is easier than revisi on of a failed total knee replacement, and the authors recommend this devic e for younger patients in whom one could expect a total knee replacement to fail within their lifetime.