[Minimally invasive medial unicompartmental knee replacement]

Medial unicompartmental knee replacements have been used for more than 40 years. Due to increased experience in determining the indication for use and improvements in design of the prosthesis and tribology, the long-term results have now reached a high level. The advantages of these systems are less bone loss and better proprioception. The disadvantage is the risk of panarthrosis, which might be reduced by accurate indications for operations. Good indications are patients older than 60 years with normal weight and normal sports activity. Well-functioning collateral and cruciate ligaments are mandatory. Due to the fact that during implantation eversion of the patella is not necessary, a minimally invasive approach might be used. Overcorrection of the mechanical axis of the leg should be avoided. By observing these principles, very good long-term results can be achieved with medial unicompartmental arthroplasty. Better proprioception and better mobility of the knee are advantages of these implants compared to total knee arthroplasty. In the case of revision with a bicondylar implant, the situation is less complex compared to revisions after osteotomies or bicondylar replacements. Remobilization in this situation is shorter with better results compared to a revision with a bicondylar prosthesis.