Review: Review ArticlesThe Use of Metaphyseal Cones and Sleeves in Revision Total Knee ArthroplastySiddiqi, Ahmed DO, MBA; Chen, Antonia F. MD, MBA; Piuzzi, Nicolas S. MD; Kelly, Michael A. MDAuthor Information From the Division of Ortho Alliance, Orthopaedic Institute of Central Jersey, Manasquan, NJ (Siddiqi), the Department of Orthopedic Surgery, Hackensack Meridian School of Medicine, Hackensack, NJ (Siddiqi, Kelly), the Department of Orthopedic Surgery, Jersey Shore University Medical Center, Neptune, NJ (Siddiqi), the Department of Orthopedic Surgery, Brigham and Women's Hospital, Boston, MA (Chen), and the Department of Orthopedic Surgery, Cleveland Clinic Foundation Cleveland, OH (Piuzzi). Siddiqi or an immediate family member serves as a paid consultant to Zimmer Biomet; serves as an unpaid consultant to AZ Solutions, LLC; and has stock or stock options held in ROMTech. Chen or an immediate family member has received royalties from AMA, Convatec, Ethicon, GLG, Graftworx, Guidepoint, Heraeus, Hyalex, Irrimax, Joint Purification System, Pfizer, PhagoMed, Recro, SLACK incorporated, Sonoran, Stryker, and UpToDate; serves as a paid consultant to AMA, Convatec, Ethicon, GLG, Graftworx, Guidepoint, Heraeus, Hyalex, Irrimax, Joint Purification System, Pfizer, PhagoMed, Recro, SLACK Incorportated, Sonoran, Stryker, and UpToDate; and serves as a board member, owner, officer, or committee member of the AAOS, AJRR, AAHKS, Annals of Joint, CORR, European Knee Association, Healthcare Transformation ICJR, JOA, JBJI, JBJS, JOR, KSSTA, and MSIS. Piuzzi or an immediate family member has received research or institutional support from RegenLab and Zimmer Biomet; serves as a board member, owner, officer, or committee member of ISCT; serves as a governing board member of the Journal of Journal of Knee Surgery, Journal of Hip Surgery, and Orthopaedic Research Society. Kelly or an immediate family member serves as a paid consultant to Acuitive Technologies, Blue Horizon, Episurf, Sanofi-Aventis, Think Surgical, and Zimmer Biomet; serves as an unpaid consultant to HealthTrust; and has stock or stock options held in Pfizer. Supplemental digital content is available for this article. Direct URL citation appears in the printed text and is provided in the HTML and PDF versions of this article on the journal's Web site (www.jaaos.org). Journal of the American Academy of Orthopaedic Surgeons: September 15, 2021 - Volume 29 - Issue 18 - p e904-e920 doi: 10.5435/JAAOS-D-20-01431 SDC Metrics Abstract The burden of revision total knee arthroplasty (rTKA) is expected to increase with the rise in the number of TKA procedures being performed yearly. Management of bone loss during rTKA is challenging and necessitates appropriate surgical planning. Metaphyseal cones and sleeves have emerged as an increasing popular option for addressing metaphyseal femoral and tibial bone loss when performing rTKA. Understanding what cones and sleeves are commercially available and when to use them are critical parts of preoperative evaluation and planning. The purpose of this comprehensive review was to present different design philosophies, types of manufacturing, clinical outcomes, and the versatility and interchangeability of varying cones and sleeves with different TKA revision systems. Copyright 2021 by the American Academy of Orthopaedic Surgeons.