Unicompartmental knee arthroplasty (UKA) - also known as unicondylar knee arthroplasty or partial knee replacement - is an excellent surgical option for the treatment of isolated medial, lateral and patellofemoral compartment arthritis of the knee, as long term results suggest high patient satisfaction and survivability that rivals total knee arthroplasty (TKA). These procedures are well-suited for rapid recovery protocols and outpatient surgery through well-structured surgical pathways. With demand increasing for knee arthroplasty, patients presenting sooner and at a younger age, and an ever-increasing interest from patients, surgeons and payors in outpatient surgery, the demand for unicompartmental arthroplasty is expected to increase significantly.  This text will assist orthopedic surgeons, sports medicine specialists, residents and attendings in developing successful pathways for unicompartmental knee arthroplasty, divided into three thematic sections. Part one discusses the history, indications and patient selection for UKA, including how to manage patient expectations, as well as implant choices. Surgical techniques for UKA are presented in part two, both the medial and lateral sides, with discussion of mobile bearings, pain management, blood preservation strategies, and therapy options both before and after surgery. Complications and their prevention are presented in part three, including periprosthetic fractures and infection.Timely and practical, Unicompartmental Knee Arthroplasty will provide orthopedic surgeons and related clinical staff with all they need to know to bring this increasingly common technique into practice.