PURPOSE OF THE STUDY There is limited evidence on survival and complication rates in patients after total knee arthroplasty for posttraumatic osteoarthritis. The failure mechanisms leading to revision remain an issue of constant debate. The purpose of this study was to analyze the mid-term survival of primary total knee arthroplasties as well as to evaluate complications and failure mechanisms in patients with posttraumatic knee osteoarthritis. MATERIAL AND METHODS This retrospective study included 79 patients with an average age of 59 years at the time of primary total knee arthroplasty. A functional and radiographic assessment was obtained during outpatient clinical follow-up at 3 and 12 months postoperatively and yearly intervals after that. Survival rates were calculated using Kaplan-Meier analyses. The mean postoperative follow-up was 69 months. RESULTS At 69 month the revision-free survival rate was 88.6%. In nine cases (11.4%) a revision procedure was performed. The leading cause of revision was a periprosthetic infection (n = 6, 66.6%). An age of fewer than 55 years at the time of total knee arthroplasty had a significant influence on implant survival (p = 0.018) with superior survival in favor of the older patient population. At most recent follow-up, a mean Knee Society Score of 82 points and an average Function Score of 77 points were observed. CONCLUSIONS Periprosthetic joint infection is the primary failure mechanism leading to a revision in patients with total knee arthroplasty for posttraumatic osteoarthritis. Apart from the increased infection rate, total knee arthroplasties in patients with posttraumatic osteoarthritis revealed results that were comparable to patients with primary osteoarthritis. Key words:posttraumatic knee osteoarthritis, total knee replacement, survival, complications, revision, outcome.