Knee osteoarthritis (gonarthrosis) is the most prevalent knee pathology encountered nowadays in the third age population, leading to severe disability and reduced life quality. Secondary gonarthrosis may be caused by a traumatic event, which subjects the knee joint to a transitory highly increased mechanical stress, initiating a rapidly progressive degrading process of the articular cartilage and subjacent bone tissue. TKA is intended to replace all the intra-articular components with artificial parts, in order to relieve pain, compensate for ligament instability, correct deformities, and restore proper joint functionality. Semi-constrained, non-hinged implants are usually used for revision TKA, in knees that already had a primary TKA but sustained complications. Nevertheless, here we reported the case of a 66-year-old female patient diagnosed with posttraumatic gonarthrosis who underwent TKA with a revision total stabilizer implant as primary treatment due to severe joint instability and high grade valgus deviation. The outcome of the surgical procedure was positive, with significant pain relief and increased knee stability. The valgus angle was reduced from 37° to 4° and the KSS score increased from 3 to 87 points. Therefore, revision semi-constrained prosthesis may be used as a primary implant with promising result in severe cases.