----Lead Forensics----

Katie Kruzan


J. Tod Fetherling

CEO / Data Geek

5.5 million patients trending toward knee joint replacements.

Predictions and targeted outreach can lead to early detection, preventive care programs, optimized care pathways, and improved patient experiences.

The CARE™ Disease Prediction algorithms from Perception Health predict that 5.5 million U.S. patients are trending toward knee joint replacement surgery. Not all of these patients will undergo knee joint replacement. Our CARE predictions help providers identify, with 93% confidence, which ones are candidates for early intervention and therapy.

Access to and the use of outpatient surgical facilities – which have both costs and complication rates lower than inpatient settings – varies widely from state to state. Many providers are building or acquiring outpatient surgical centers as a defensive strategy within the orthopedic service line.  The facilities tend to be located nearer to the patient and not co-located with the acute care hospital. This may create an opportunity for providers to keep up with demand and provide better patient outcomes.

Knee joint replacement surgery replaces damaged or worn surfaces of the knee, often caused by injury or osteoarthritis, and in some cases exacerbated by obesity. It has become a more common procedure in recent decades, even for people under 55, suffering from joint pain and limited mobility.

When the procedure is predicted before diagnosis, earlier detection is possible, preventive care management can be prescribed, and a care network can be optimized, resulting in an improved patient experience.

This advanced notice can result in substantial benefits for the patient. But providers – particularly hospitals  – must take these predictions for surgery into account as health insurers increasingly push members toward outpatient facilities. With information from CARE and TEAM, hospital administrators will be able to predict and identify pockets of populations that trend towards these early indicators and take action. This could include creating and opening new surgery centers and other facilities where pre/post services are more convenient for patients.

The push from insurers may be driven primarily by financial considerations. The cost difference for outpatient vs. inpatient knee procedures ranges from 30 to 40 percent. The average inpatient knee replacement is $30,249, compared to $19,002 for an outpatient procedure. Despite these potential savings, only 11% of knee procedures were performed on an outpatient basis in 2017. Given that a record number of consumers are paying higher out of pocket costs, we expect the consumer voice to get much stronger when it comes to the selection of their surgical sites.

Additionally, outpatient complication rates have improved by 23 percent for knee procedures from 2013 to 2017 and are lower than inpatient complication rates.

However, the shortage of outpatient facilities can be a potential problem, even as the global knee replacement market is projected to be worth over $10 billion by 2024. Furthermore, orthopedic surgery is the 10th highest-demanded surgical specialty, according to the 2018 Incentive Review for Physicians and Advanced Practitioners by Merritt Hawkins.

Perception Health's prediction is based on comparative models that examined 130,000 recent patient claims. CARE™ compared two data sets:

  • Claims histories of patients who include a code related to knee joint replacement after Jan. 1, 2016.
  • Claims histories patients who didn't have these codes in their records.

We looked at ICD-10 Diagnoses and CPT Codes that are commonly found in people who had knee replacements. The codes dealt with orthopedics, hospital visits, radiology, and cardiovascular.

The data set we used to train the model was comprised of 50% patients (those who had a knee-joint replacement) and 50% non-patients (people without the knee joint replacement in their claims history). Then we trained our model on 70% of that data set and then tested on 30% of that same data set.

From the ROC curve, the area under curve (AUC) is calculated as 0.968, and the Random Forest model was accepted with a model confidence value of 0.928.

Knee Joint Replacement Slope of Care

Out of a random 10,000 patients, 14 had knee replacements in their claims history. But with CARE, we predict that another 169 patients are trending toward knee joint replacement. The claims histories of these 169 patients showed similar diagnoses and/or procedures when compared to the patients who had the surgery.

Using the CARE Disease Prediction algorithm, we wanted to see how many days back we could correctly predict a knee joint replacement diagnosis and got the following results (see right):

We then projected our results nationally, which translated to approximately 391,000 patients who have had a knee joint replacement surgery and 5.5 million people who have not yet had a knee joint replacement surgery, but have indicators that they are trending towards that surgery.


The growth in knee joint replacements is expected to last for decades. The American Academy of Orthopaedic Surgeons predicts 1.28 million procedures (189% increase) by 2030 and 2.6 million procedures (382% increase) by 2060. Healthcare providers who strategize how to address the increase can now profit from the growth in demand while improving the quality of life for those suffering from joint pain.

Total Knee Replacement Surgery By the Numbers