Anterior knee pain after total knee arthroplasty. Causes, diagnosis and treatment

Anterior knee pain is one of the most common complications after total knee arthroplasty. An incidence of up to 30 % has been reported in peer-reviewed studies. The purpose of this study was to systematically review the literature and to identify determinants that have been analyzed with regard to anterior knee pain. Patient- and knee-specific characteristics, prosthetic designs and operative techniques are addressed as well as functional and neurologic determinants. Instability, increased contact pressure in the patellofemoral joint and patella maltracking due to malrotation of components, offset errors, ligament insufficiencies or patella baja are mechanical reasons for anterior knee pain. Functional causes include pathologic gait patterns, quadriceps imbalance and dynamic valgus. They have to be differentiated from infectious and inflammatory causes as well as soft tissue impingement, arthrofibrosis and neurologic diseases. A differentiated treatment algorithm is recommended. Often conservative treatment options exist, however, particularly with most mechanical causes revision surgery is necessary.