The optimal treatment of complex tibial plateau fractures in elderly is still controversial. The aim of the study was to retrospectively analyze the clinical and radiological outcomes of primary total knee arthroplasty (TKA) versus open reduction and internal fixation (ORIF) in elderly patients presenting with acute complex tibial plateau fractures. Between June 2011 and December 2015, we have analyzed the clinical outcomes of 22 primary total knee replacements and 21 ORIFs. The mean follow-up was 27 months. The intra- and postoperative complications, as well as the knee society score (KSS), were our outcome measures. The knee range of motion and the KSS knee and function scores were significantly better in the TKA patients compared with ORIF patients. Early postoperative full weight-bearing was allowed in the TKA patients with lower complications rate. In conclusion, primary TKA utilizing a stemmed tibial component is an effective treatment option for elderly patients with a complex acute fracture of the tibial plateau. This is a Type III therapeutic study.