Need Knee Surgery? A Before & After Control Chart Can Help You Decide

Joshua Zable | 4/17/2024

Topics: Control Charts, Healthcare, Minitab Statistical Software

My father recently had knee surgery, so I’ve had the “pleasure” of spending a lot of time at a hospital. While my father was sleeping, being attended to, or being visited by others, I had plenty of time to wander the hallways. As a data person, I gravitate towards the graphs on the wall, so when I see an opportunity for improvement…I blog about it. And while this can truly help surgeons better communicate with their patients, my family would kill me if I spent time talking to the surgeon about graphs on the wall versus asking about my dad’s condition!

To Have Knee Surgery or Not to Have Knee Surgery, That is The Question

“Whether 'tis nobler in the mind to suffer the slings and arrows” of a painful knee or opt to have surgery,… is something Hamlet himself would have wrestled with (had he A) had a bad knee, and B) had the option of knee replacement surgery). Whether you’re a prince of Denmark or an average David (that’s my Pops!) making a decision about knee surgery is a big one. It typically comes down to two questions: 1) can I live with the pain? and 2) what will the improvement look like?

Hospital Have Graphs to Show Improvement Post Surgery…They’re Just Confusing

As patients consider surgery, they are often given a questionnaire designed to assess both short-term and long-term patient-relevant outcomes called a Knee Injury and Osteoarthritis Outcome Score (KOOS). The purpose of the score is to evaluate five outcomes:

  1. Pain: Measures the severity of knee pain
  2. Symptoms: Assesses other symptoms related to the knee
  3. Activities of Daily Living (ADL): Evaluates how well an individual can perform daily tasks
  4. Sport and Recreation Function: Focuses on knee function during physical activities
  5. Knee-Related Quality of Life: Assesses the impact of knee health on overall quality of life

The KOOS consists of 42 items, each scored from 0 (no problems) to 4 (extreme problems). These scores are then normalized to a 0-100 scale, where higher scores indicate better knee health.

To measure the improvement of the KOOS scores – based on what I’ve witnessed – they measure the pre-operation KOOS scores and post-operation KOOS scores using spreadsheet graphs.

Here’s what I see on hospital walls:



To see the improvement for the pre-operation KOOS score to the post-operation KOOS score, one has to look really closely at the graphs, specifically the percentages. One simple glance and it might even give one an impression that the surgical outcomes did not alleviate much pain.

Learn From Continuous Improvement Pros: How Hospitals Can Show Improvement Clearly

Using Before/After Control Charts (which can be easily created using stages for any type of Control Chart), you can quickly and easily highlight changes, in this case improvements. Control charts, used almost universally in manufacturing, are a great tool to help address undesirable outcomes and determine if a process is “in control” (i.e. predictable). After all, if “something is rotten in the state of Denmark,” and it’s your process, not a ghost, then you’d want to know, right?

In this case, the staged Individuals Chart below clearly demonstrates how the KOOS scores improved post-surgery, making it very easy for physicians to articulate the benefits of surgery in an easy, digestible way. Plus, using only one graph opens up free wall space for maybe a famous quote from Shakespeare.


Before and after control chart in Minitab


Improve and Enhance Patient Care with minitab

Minitab allows hospitals to use before and after control charts to measure and showcase improvement post knee surgery - or any surgery or treatment -  in a better and easier way for their patients. As hospitals strive to offer the best care for their patients, harnessing the power of data-driven insights is vital for success.


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