The limb alignment in weight-bearing position is regarded as vital to total knee arthroplasty. Unicompartmental arthroplasty has had uneven success and its failure due to implant or to surgical technique was discussed in the current literature. Basic research and the clinical application of ceramics were introduced. The clinical results of knee replacement using ceramics were satisfactory, but improvement may be anticipated. This review covers recent research on alignment, unicompartmental replacements, ceramics in knee arthroplasty, and the problems of patellar tracking in total knee arthroplasty.