Minimally invasive unicompartmental knee replacement Literature review

Nowadays the demand for Unicompartmental Knee Replacement (UKR) for the treatment of degenerative arthritis or osteonecrosis of a single compartment of the knee is increasing. The procedure has significantly evolved through the past three decades and we present an extended review of the literature on this topic. A detailed historical overview is reported, in order to follow the subsequent hypothesis that have led to the modern state of the art in Minimally Invasive Surgery (MIS) for UKR and to the resurgence of the concept of interpositional hemiarthroplasties. We have also performed a review of the literature regarding the evolution of indications and contraindications for a UKR, as well as pre-operative evaluation and surgical technique. In separated sections, we have also reported findings and concepts regarding lateral UKR and its surgical technique and also recent diffusion of bi-unicompartmental procedures. A wide section is dedicated to the discussion about different implant designs, considering their biomechanical and kinematics basis and to generally accepted guidelines for the correct implant positioning. The recent advances in Computer Aided Surgery (CAS) related to UKR are also discussed. Finally, we have analysed the modes of failure of UKRs and their surgical implications and the topic of the revision procedures for a failed UKR.