Back pain — which 31 million people in the U.S. experience at any given time — is the leading cause of disability worldwide. It’s also the most common reason for missed work, and the second-most common reason for visits to the doctor’s office.

Prescription painkillers and chiropractic consultations can help reduce some pain, but Konstantin Mehl and Innocent Clement believe there’s a better, cheaper, and more sustainable way. They cofounded Kaia Health, a startup that leverages artificial intelligence (AI) and motion-tracking technology to build a treatment program with no more than a smartphone or tablet.

That might sound too good to be true, but Kaia has empirical evidence on its side. In a clinical study conducted at the Technical University of Munich’s Center for Pain Therapy and other leading institutions in Germany, its app-based approach reduced lower back pain by 40 percent. And a slew of independent research — including a 2011 study of chronic pain — has shown its brand of psychotherapy to be an effective form of treatment for long-term ailments.

Kaia Health

“The Kaia app and advances in technology demonstrate why we need to rethink how we treat disease conditions such as LBP, and why [we need to] make digital self-management a more realistic part of treatment,” Mehl said.

The app, which previously launched in Germany and the U.K. and hits U.S. shores today, was developed with advisement from “physiotherapists,” “pain management physicians,” “orthopedic surgeons,” and “clinical psychologists,” Kaia Health claims. (It’s registered as a Class 1 medical device with the Food and Drug Administration.) It tracks connective points on the body using an iOS or Android device’s front-facing camera, which it uses in tandem with an on-screen wireframe model to walk users through any of 120 15-minute exercises.

The Kaia app’s video portal contains clips covering basic back pain information, step-by-step physiotherapy exercises for the lower back and lateral muscles, and psychological strategies such as mindfulness and muscle relaxation. And a built-in chat tool lets users consult with a physiotherapist or sports scientist on questions related to exercises.

Not so incidentally, the Kaia app’s underlying algorithms power the two other apps in Kaia Health’s portfolio: the Perfect Squat Challenge and Kaia COPD. The former gives real-time audio feedback on users’ poses, and Kaia COPD walks patients with chronic obstructive pulmonary disease through breathing exercises designed to reduce lung inflammation that can obstruct airflow.

“Opioid addiction and overdose is a huge issue in the U.S., and, according to the ACP, is a last resort for those suffering from [lower back pain]. A holistic, multidisciplinary treatment of LBP has always been a resource-intense [and] costly undertaking, which makes it hard for patients to get access to the therapy,” Mehl said.

The Kaia app was downloaded more than 100,000 times in Germany in its first year of availability, according to the company, and 40 percent of people continued to use it roughly 3 times a week for at least six months.

It’s not free — subscription plans start at $24 for three months after a seven-day trial — but thanks to reimbursement deals with German health insurance companies, it’s available at no charge to about 20 million patients.

“[W]ith the Kaia app,” Mehl said, “we’re digitizing therapy that offers as many patients as possible access to effective treatment of LBP. This empowers and motivates individuals to take control and self-manage their condition with evidenced-based, non-pharmacological, cost-effective alternatives.”

According to Crunchbase, Kaia Health has raised $4 million since 2015.