Streaming Media

Name of Corresponding Author

Colleen Kordish

Credentials of Corresponding Author



In this study, a series of conditions thought to be necessary but not sufficient for a patient’s timely discharge after total knee replacement will be analyzed using necessary condition analysis to determine if these conditions are necessary but not sufficient for a particular length of stay (LOS) in hospital and at what level of the condition.

Background and significance

Timely extubation after surgery is considered a best practice but there is not currently an optimal time specified. In this study, necessary condition analysis will be used to statistically analyze the relationship between extubation times post knee surgery and LOS. Understanding this relationship can be used to optimize patient care and hospital processes.

Theoretical/Conceptual framework

Systems theory states that to understand the whole, the relationship between the many parts of the whole must be analyzed. In this study, the relationship between extubation and surgical LOS will be examined to understand how the timing of extubation may affect LOS.


The Loyola Clinical Research Database was used to identify hip and knee replacement surgeries between June 2018 – June 2020. Necessary condition analysis was then used to analyze the relationship between time of extubation and patient LOS. BMI and surgery type will also be analyzed as possible conditions affecting LOS.


The data from 486 knee replacement patients, 62% female, 28% minorities, mean age 66 years (range 29 – 88yrs), was analyzed. The mean LOS was 77.39 hours (SD 44.5 hours). Complete analysis forthcoming.


Most processes are a series of conditions that are intertwined and result in an outcome. Common statistical analyses uses regression, whereby the relationship between the average condition and the average outcome is calculated. A different thought process prevails when using necessary condition analysis (NCA). NCA is based on the logic of necessity. In necessity logic, if a condition is necessary, then the outcome cannot be obtained without the condition. Understanding the extubation time that is necessary to achieve a specified LOS outcome can assist hospital staff in early resource planning and optimizing patient care.



Necessary Condition Analysis: Conditions for Surgical Length of Stay in Knee Replacement