Anterior knee pain after a total knee arthroplasty: What can cause this pain?

Abstract

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.

Keywords: Anterior knee pain; Homeostasis; Malrotation; Patellofemoral pain; Total knee arthroplasty.

Figure 1

Applying Dye’s theory to patients with Anterior Knee Pain after total knee arthroplasty provides useful insights. A: The potential range of activity or envelope of function for a specific joint: all activities fall within the zone of homeostasis except the jump from 3 m height¹; B: The different zones of loading across the knee joint. The first zone is the zone of subphysiological underloading, the second is the preferred zone of tissue homeostasis, the third is the zone of supraphysiological overloading and the fourth is the zone of structural failure; C: Arthritis causes the potential range of activity (envelope of function) to become limited, causing pain and restrictions in daily activities such as walking and cycling. The dotted line is the original zone of homeostasis for this specific knee; D: The postoperative situation where total knee arthroplasty placement increases the potential range of activity but does not return it to the original range of activity. (Reprinted with permission from Dye et al[6]).