Defining Outpatient Hip and Knee Arthroplasties

A Systematic Review

Samuel G. McClatchy, MD; Carson M. Rider, MD; William M. Mihalko, MD, PhD; Zachary K. Pharr, MD; Patrick C. Toy, MD


J Am Acad Orthop Surg. 2021;29(8):e410-e415. 

In This Article

Abstract and Introduction


Introduction: The term "outpatient" has a variety of meanings regarding the location of arthroplasty and the duration of stay postoperatively. The purpose of this systematic review was to evaluate the literature and more accurately define the term "outpatient."

Methods: A PubMed search (2014 to 2019) using the terms "outpatient AND arthroplasty" identified 76 studies; 35 studies that met the inclusion criteria were assessed to determine the definition of "outpatient." The level of evidence, type of arthroplasty, location of surgery (hospital or ambulatory surgery center [ASC]), approach used for hip arthroplasty, number of patients, number of surgeons, and length of time the patients were kept at the location after surgery were evaluated.

Results: Arthroplasties analyzed were total hip (11), total knee (seven), unicompartmental knee (five), and hip and knee (12). Only 16.8% of surgeries defined as outpatient hip or knee arthroplasty were done in a freestanding ASC, and 44.2% of patients defined as outpatients were kept overnight for the 23-hour observation.

Discussion: We propose "DASH" (Discharge from ASC to Home) as a new term to define arthroplasties done in an outpatient setting with the patient discharged home the same day.


Outpatient hip and knee arthroplasties have become a popular treatment option for both patients and surgeons over the past several years. Rapid recovery protocols, more efficient ambulatory surgery centers that allow more surgeon control, and patients' desire to recover in their own homes have all contributed to this increase in popularity.[1] Outpatient hip and knee arthroplasties have also been proven to be safe for the appropriate patients[2–4] and a cost-effective alternative to inpatient arthroplasty.[5] Arthroplasty in the outpatient setting is rapidly growing with expectations that more than half of primary total hip and knee arthroplasties will be done in an outpatient setting by the year 2026.[6,7]

As the outpatient hip and knee arthroplasty literature and discussions grow, so does the diversity of outpatient protocols. Joint arthroplasties done in the hospital, kept overnight but discharged within 23 hours,[7,8] and arthroplasties done in a freestanding orthopaedic ambulatory surgery center (ASC) and discharged home the same day[2] have been described in the literature when discussing outpatient arthroplasty and highlight the diversity currently seen in this field. The term "outpatient" has a wide variety of meanings regarding the location of surgery, the duration of stay postoperatively, and the discharge destination.

By surveying the outpatient arthroplasty literature, our purpose was to more accurately define the term "outpatient arthroplasty" because it applies to hip and knee surgeries and to propose a novel term to define hip and knee joint arthroplasties done as a same-day procedure and discharge-to-home process. Our hypothesis is that the literature definition of outpatient hip and knee arthroplasties is inconsistent and that outpatient arthroplasty does not represent the same-day procedure and discharge to home.