Inpatient vs Outpatient Total Knee Replacement


This is a randomized clinical trial comparing standard inpatient (overnight hospital stay) total knee arthroplasty with same day discharge. Patients who are medically well and have a good support structure at home will be randomized to inpatient or same day discharge. This study will compare patient satisfaction and costs from the perspectives of the Ministry of Health, the institution, society and the patient. Caregivers will also be enrolled to investigate caregiver strain and assistance in the early postoperative period.

Full Title of Study: “Cost and Patient Satisfaction Associated With Total Knee Arthroplasty”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Health Services Research
    • Masking: Double (Participant, Care Provider)
  • Study Primary Completion Date: March 2023

Detailed Description

Osteoarthritis (OA) is a leading cause of disability and reduced quality of life, presenting a substantial, growing burden to patients and the healthcare system (1). Total knee arthroplasty (TKA) is an established, effective interventions for advanced OA. The prevalence of knee OA is rapidly increasing, resulting in a rising demand for care. The number of procedures is expected to grow by 48%, by 2020 in the US (2). Currently, TKA along with total hip arthroplasty (THA), have a significant impact on healthcare budgets, costing approximately $1.2 billion in annual spending in Canada (3). These staggering numbers highlight the critical need to improve care delivery.

A significant proportion of the overall cost of joint replacement results from the inpatient hospital stay following the procedure. Historically, the standard procedure following TKA required an inpatient hospital stay of two and a half to three weeks, however the introduction of less invasive surgical techniques, improved medical and analgesia management and comprehensive rehabilitation have enabled shorter inpatient stays. Today, the median inpatient stay following TKA is three days in Canada (3). A desire for greater autonomy by the patients as well as patients wanting early mobilization to accelerate recovery and return to activities has led some clinicians to consider an outpatient arthroplasty program. The proposed benefits of outpatient arthroplasty include similar patient outcomes with significantly lower hospital costs, and improved patient satisfaction, independence, and autonomy, however there is a lack of high-quality evidence comparing clinical outcomes of outpatient to inpatient arthroplasty models of care.

A retrospective analysis of over 50,000 THA and TKA procedures found no differences in 30-day major complications or readmissions among patients with a zero to two-day hospital stay compared to those discharged on day three or four postoperative (4). Small cohort studies (5-8) suggest lower costs for outpatients and improved patient satisfaction but have inherent biases; limited to carefully selected patients in privatized health systems.

It is estimated that up to 20% of the overall cost of joint replacement can be attributed to the inpatient stay in hospital at our institution (9). By discharging patients as outpatients, it could be possible to save 20% of the overall costs of joint replacement. Although these preliminary calculations are encouraging, it is not sufficient to effect change solely to achieve cost control, without consideration of safety, effectiveness and patient satisfaction. Further, it is unknown whether the financial savings will be outweighed by additional postoperative costs, increased readmissions or decreased quality of care. A full economic evaluation that simultaneously evaluates cost and effectiveness is crucial prior to implementation. The lack of high-quality evidence regarding its effectiveness warrants a rigorous comparative trial.

The purpose of this study is to evaluate outpatient care pathways for TKA. Specifically, our objectives are to compare the rate of serious adverse events and estimate the cost-effectiveness of outpatient compared to standard inpatient TKA.


  • Procedure: Outpatient
    • Patients in the outpatient group will be discharged from the hospital the same day of surgery following a total knee arthroplasty
  • Procedure: Inpatient
    • Patients in the inpatient group will be discharged from the hospital the following day after a total knee arthroplasty

Arms, Groups and Cohorts

  • Experimental: Outpatient
    • Patients in the outpatient group (same day discharge following TKA) are discharged the same day following surgery. All patients are required to meet the discharge criteria to be sent home (i.e., capable of using crutches, relatively free of pain, free of nausea and vomiting, free of excess bleeding, alert and oriented, given take-home medications, and in the company of a caregiver).
  • Active Comparator: Inpatient
    • Patients in the inpatient group (following day discharge following TKA) stay in the hospital overnight and then are discharged home the next day. All patients are required to meet the discharge criteria to be sent home (i.e., capable of using crutches, relatively free of pain, free of nausea and vomiting, free of excess bleeding, alert and oriented, given take-home medications, and in the company of a caregiver).

Clinical Trial Outcome Measures

Primary Measures

  • Indirect and direct costs of treatment
    • Time Frame: 1 Year
    • ER visits, clinician visits, caregiver lost productivity, tests, etc.
  • Rate of early complications and adverse events
    • Time Frame: 1 Year
    • fall, wound problems, pulmonary embolism, deep vein thrombosis, infection, etc.
  • Standardized measure of health outcome (EQ-5D)
    • Time Frame: 1 Year
    • utility score measured on a scale of 0 (death) to 1 (perfect health)

Secondary Measures

  • Patient satisfaction questionnaire
    • Time Frame: 2 Weeks
    • patient satisfaction with care pre-, peri- and postoperative
  • Western Ontario McMaster Osteoarthritis Index (WOMAC)
    • Time Frame: 1 Year
    • functional outcome measured on a total scale of 0 (better function) to 100 (worse function) and made up of subscales for pain, stiffness and function
  • Knee Society Score
    • Time Frame: 1 Year
    • functional outcome measured on a scale of 0 (worse function) to 100 (best function)
  • Short Form 12
    • Time Frame: 1 Year
    • quality of life measured on a scale of 0 (worse) to 100 (better) using norm-based scoring
  • Pain Numeric Rating Scale
    • Time Frame: 1 Year
    • pain measured on a scale from 0 (no pain) to 10 (worst pain imaginable)
  • Caregiver Assistance Scale
    • Time Frame: 6 Weeks
    • amount of assistance provided measured with 17 questions each on a 7 point likert scale from 0 (none) to 6 (a lot), higher total scores indicate more assistance
  • Caregiver Strain Index
    • Time Frame: 6 Weeks
    • caregiver strain scored from 0 to 13 with scores greater than 7 indicating a high level of stress

Participating in This Clinical Trial

Inclusion Criteria

  • American Society of Anaesthesiologists (ASA) score equal to or less than 3
  • Have the ability to read and understand English (printed instructions are provided in English only)
  • Live within a 60 minute driving distance of University Hospital (UH)
  • Home / cell phone access
  • An adult to accompany patient home post-operatively
  • Sufficient caregiver support
  • Caregivers: identified as the main caregiver for the participant in the immediate postoperative period (can be family or friend)

Exclusion Criteria

  • Patient has significant pain management issues
  • Patient / family history of anesthesia related complication(s) (e.g., malignant hyperthermia, pseudocholinesterase deficiency, airway difficulties, obstructive sleep apnea)
  • Obesity that significantly impacts the patient's ability to mobilize
  • Anaphylaxis to penicillin
  • Significant psycho / social issues that would prevent the patient from managing at home safely
  • Cognitive issues that preclude the ability to understand instructions
  • Lack of an appropriate social network that can observe the patient post-operatively
  • Caregivers: inability to speak/read English as questionnaires are only available in English

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • Lawson Health Research Institute
  • Provider of Information About this Clinical Study
    • Principal Investigator: Brent Lanting, Associate Professor – Lawson Health Research Institute
  • Overall Official(s)
    • Brent Lanting, MD, FRCSC, Principal Investigator, London Health Sciences Centre
  • Overall Contact(s)
    • Jacquelyn Marsh, PhD, 519-661-2111,


Kurtz SM, Ong KL, Lau E, Bozic KJ. Impact of the economic downturn on total joint replacement demand in the United States: updated projections to 2021. J Bone Joint Surg Am. 2014 Apr 16;96(8):624-30. doi: 10.2106/JBJS.M.00285.

Sutton JC 3rd, Antoniou J, Epure LM, Huk OL, Zukor DJ, Bergeron SG. Hospital Discharge within 2 Days Following Total Hip or Knee Arthroplasty Does Not Increase Major-Complication and Readmission Rates. J Bone Joint Surg Am. 2016 Sep 7;98(17):1419-28. doi: 10.2106/JBJS.15.01109.

Aynardi M, Post Z, Ong A, Orozco F, Sukin DC. Outpatient surgery as a means of cost reduction in total hip arthroplasty: a case-control study. HSS J. 2014 Oct;10(3):252-5. doi: 10.1007/s11420-014-9401-0. Epub 2014 Jul 12.

Bertin KC. Minimally invasive outpatient total hip arthroplasty: a financial analysis. Clin Orthop Relat Res. 2005 Jun;(435):154-63.

Lovald ST, Ong KL, Malkani AL, Lau EC, Schmier JK, Kurtz SM, Manley MT. Complications, mortality, and costs for outpatient and short-stay total knee arthroplasty patients in comparison to standard-stay patients. J Arthroplasty. 2014 Mar;29(3):510-5. doi: 10.1016/j.arth.2013.07.020. Epub 2013 Aug 21.

Kolisek FR, McGrath MS, Jessup NM, Monesmith EA, Mont MA. Comparison of outpatient versus inpatient total knee arthroplasty. Clin Orthop Relat Res. 2009 Jun;467(6):1438-42. doi: 10.1007/s11999-009-0730-0. Epub 2009 Feb 18.

Petis SM, Howard JL, Lanting BA, Marsh JD, Vasarhelyi EM. In-Hospital Cost Analysis of Total Hip Arthroplasty: Does Surgical Approach Matter? J Arthroplasty. 2016 Jan;31(1):53-8. doi: 10.1016/j.arth.2015.08.034. Epub 2015 Aug 29.

The Arthritis Alliance of Canada, The Impact of Arthritis in Canada: Today and over the next 30 Years, 2011

Canadian Institute for Health Information. Hip and Knee Replacements in Canada, 2017-2018: Canadian Joint Replacement Registry Annual Report. Ottawa, ON: CIHI; 2019.

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