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Groundbreaking Study on Apple Health and Patient Recovery

In a groundbreaking study presented at the 2025 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS), researchers unveiled the potential of the Apple Health app in assessing recovery metrics after lower extremity surgeries, including tibial plateau, distal femur, and femoral shaft fractures.

The Apple Health app has long been a tool for users wanting to monitor various health indicators like heart rate and blood oxygen levels. The study leverages its mobility data to aid in tracking patient recovery. Using advanced mixed-effect models, the researchers compared key mobility metrics with the aim of providing an objective measure of improvement over time. The mobility data collected from patients prior to their injuries served as a critical baseline.

Dr. Dane J. Brodke, an assistant professor at Oregon Health & Science University, emphasized the significance of this data in the rehabilitation process. "Traditionally, assessing recovery from traumatic leg injuries has been fraught with challenges due to the absence of objective data. With platforms like Apple Health passively gathering this information, we can objectively measure a patient’s mobility before and after injury, providing essential context for their recovery. This baseline is typically not available through other functional outcome measures."

The study, titled The Future is Mobile Validating Apple Health as a Novel Orthopaedic Trauma Outcome Metric, led by Dr. Brodke alongside Brian Shear, MD, and Nathan O'Hara, PhD, MHA, aimed to determine if the outcome measures derived from Apple Health could effectively capture mobility changes associated with injuries, correlate with patient-reported outcomes (PROs), and differentiate patients with or without complications such as nonunion, where a bone fails to heal adequately.

Methodology

The study focused on a cross-sectional analysis of adult patients with lower extremity fractures who owned iPhones and had a minimum of six months of follow-up. Participants shared Apple Health data while also completing Patient Reported Outcomes Measurement Information System (PROMIS) surveys, which analyze physical function and pain. The key metrics examined included daily step count, walking asymmetry, double support time, walking speed, and step length.

Mixed-effects models were utilized to analyze the mobility metrics at three pivotal time points: 28 days prior to injury, during the first 28 days post-injury, and six months following the injury. Additionally, researchers assessed correlations between mobility metrics and PROMIS physical function and pain interference scores.

Key Findings

The results were striking. The researchers noted that all five mobility metrics indicated significant decline from the pre-injury assessments. For instance:

• - Daily step count saw a decrease of 93%,
• - Walking speed diminished by 9%,
• - Step length reduced by 6%,
• - Walking asymmetry spiked by 88%,
• - Double support time increased by 1%.

Six months post-injury, the data revealed notable recovery, as:

• - The average daily step count rose to 2,430—a remarkable 655% increase from the early post-injury phase—though still 52% lower than pre-injury levels.
• - Walking speed and step length continued to decline in the initial recovery phase, while walking asymmetry and double support time increased.

Interestingly, step count correlated most strongly with patient-reported physical function. Patients with nonunions exhibited a 55% slowdown in their recovery compared to peers who healed without complications.

Dr. O'Hara noted, "These findings underscore that data derived from smartphone-measured step counts not only correlate with negative clinical outcomes but could also serve as predictors, enabling earlier intervention and enhancement in patient care. If a patient's recovery plateaus, it could indicate that they have reached their maximum potential for improvement. While PROMIS surveys provide subjective insights, Apple Health’s objective data offers a more consistent understanding of recovery."

The Road Ahead

The research team is in the process of developing an application that can be downloaded during a patient's first visit with their orthopaedic surgeon, with the goal of encouraging more participants to track their Apple Health data. By harnessing this innovative technology, they hope to offer patients tailored insights that will facilitate recovery and promote a safe return to their usual active lives.

The AAOS, with over 39,000 members, continues to lead advancements in musculoskeletal health and provides comprehensive education to orthopedic professionals, highlighting the importance of integrating technology in medical practices.