Total Knee Arthroplasty has been shown to be a successful procedure for treating patients with osteoarthritis, and yet approximately 5%-10% of patients experience residual pain, especially in the anterior part of the knee. Many theories have been proposed to explain the etiology of this anterior knee pain (AKP) but, despite improvements having been made, AKP remains a problem. AKP can be described as retropatellar or peripatellar pain, which limits patients in their everyday lives. Patients suffering from AKP experience difficulty in standing up from a chair, walking up and down stairs and riding a bicycle. The question asked was: "How can a 'perfectly' placed total knee arthroplasty (TKA) still be painful: what can cause this pain?". To prevent AKP after TKA it is important to first identify the different anatomical structures that can cause this pain. Greater attention to and understanding of AKP should lead to significant pain relief and greater overall patient satisfaction after TKA. This article is a review of what pain is, how nerve signalling works and what is thought to cause Anterior Knee Pain after a Total Knee Arthroplasty.© 2014 Baishideng Publishing Group Inc. All rights reserved. Key words:Anterior knee pain; Patellofemoral pain; Total knee arthroplasty; Malrotation; Homeostasis Core tip: Total knee arthroplasty (TKA) has been shown to be a successful procedure for treating patients with osteoarthritis, and yet approximately 5%-10% of patients experience anterior knee pain (AKP). To prevent AKP after TKA it is important to first identify the different anatomical structures that can cause this pain. Greater attention to and understanding of AKP should lead to significant pain relief and greater overall patient satisfaction after TKA. This article is a review of what pain is, how nerve signalling works and what is thought to cause AKP after a TKA.Breugem SJM, Haverkamp D. Anterior knee pain after a total knee arthroplasty: What can cause this pain? World