Mayo Hip Dislocation Risk Calculator Unveiled

New work, based on two decades of data from Mayo Clinic in Rochester, Minnesota (“Creation of a Total Hip Arthroplasty Patient-Specific Dislocation Risk Calculator”) has found that risk at the individual patient level can be successfully calculated using an unusually comprehensive screening tool. The study appears in the June 15, 2022, edition of The Journal of Bone and Joint Surgery.

Describing their calculator as a “high-dimensional, patient-specific risk prediction model for dislocation following THA [total hip arthroplasty] that allows for dynamic risk modification based on operative decisions,” the researchers looked at 29,349 THAs (21,978 primary and 7,371 revision cases) performed over two decades between 1998 and 2018.

Drilling down, the Mayo team was able to create a risk prediction model using a wide range of variables and that can be adapted to decisions within the surgeon’s control. Specifically, they examined “instability comorbidities” such as neurologic disease, spine disease, and spine surgery.

The paper’s first author, Cody Wyles, M.D., told OTW, “Despite many advances, dislocation remains the most common complication after THA and is one of the most common reasons for revision surgery.”

“Intuitively, surgeons know that patients have different baseline risks for dislocation and that surgical factors such as approach, head size, and liner type can modulate this risk. However, no tool previously existed to quantify a patient’s baseline risk and the degree to which the risk is changed by different surgical decisions.”

“Our tool is the first to provide this knowledge so that surgeons can make informed patient-specific choices to manage the most prevalent complication of THA.”

Power to the Surgeon

“We found that baseline risk was extremely wide-ranging, from 0.3%-3.0% at 1 year and from 0.4%-19.0% at 5 years after primary THA, and from 2.0%-32.0% at 1 year and from 3.0%-42.0% at 5 years after revision THA.”

“Despite these grim and humbling statistics, the second primary message of the paper is hopeful. That is, surgeons have enormous power to modify risk. Surgical approach, femoral head size, and acetabular liner type are the most influential factors in the model, meaning that surgeons can do a great deal to manage risk.”

“We further identified that in the revision setting, acetabular revision independently decreased risk by 40%. We would encourage readers to consult the Tables and Figures in the manuscript for details of the risk reduction for each variable.”

“There are very few databases that have the detail, longitudinal follow-up, and complete capture of postoperative outcomes to conduct a study of this sort. The most important variable here is the capture of postoperative outcomes.”

“Even some of the most complete registries only capture revision for dislocation, yet that constitutes the minority of this complication. We are fortunate that the Mayo total joint registry captures all dislocations even if they occur outside of our health system.”

“This tool is the first of its kind to quantify patient-specific baseline risk and the degree to which risk is modulated by decisions within a surgeon’s control. As a preoperative tool, this will enable surgeons to screen for high-risk patients and determine which patients would benefit from alternative intraoperative management.”