Preface: ATM special section: lower extremity arthroplasty

This special section of Annals of Translational Medicine focuses on important topics and techniques in total knee arthroplasty (TKA) and total hip arthroplasty (THA). It is not only meant for the orthopaedic audience, but also for the general readership who are interested in learning about the application of various surgical concepts. Therefore, we purposefully included studies evaluating a wide range of procedures and patient populations.