Anterior dislocation of a posterior stabilised total knee arthroplasty secondary to a polyethylene tibial post fracture is rare. We report one such case in an 89-year-old Chinese woman who had undergone total knee arthroplasty using the Insall Burstein II prosthesis 7 years earlier. The failure was due to sagittal malalignment of the components. Owing to more pronounced anterior bowing of the distal femoral shaft in southern Chinese, neutral component placement is often biased toward hyperextension. When the knee reaches full extension, anterior impingement occurs. Surgeons must therefore take extra care in preoperative planning and bone cutting in this population.