A 10-year study of over 1,200 patients reveals that runner's knee, medically known as patellofemoral pain (PFP), may be far more than a minor annoyance. Researchers at Ochsner-Andrews Sports Medicine Institute found that people diagnosed with PFP face a 3.6 times higher risk of tearing their anterior cruciate ligament (ACL), the crucial ligament that stabilizes the knee, compared to the general population . The findings suggest that PFP should be treated as an early warning signal rather than an isolated injury, especially in young athletes.

What Does the Research Actually Show?

The study tracked 1,232 patients diagnosed with patellofemoral pain between 2014 and 2018, then followed their medical records through 2024 to identify subsequent knee injuries . The results were striking: patients with PFP experienced ACL injuries at a rate of 246 per 100,000 person-years, compared to just 68.6 per 100,000 in the general population. Even more telling, 83% of the subsequent knee injuries occurred on the same side where the original patellofemoral pain was diagnosed . This pattern strongly suggests a biomechanical relationship rather than a systemic weakness affecting both knees equally.

The timing of these injuries matters too. The median time between a PFP diagnosis and the first subsequent knee injury was 10 months, with most injuries clustering within the first year after the initial diagnosis . This concentrated window of vulnerability creates a critical opportunity for intervention before more serious damage occurs.

Why Does Runner's Knee Increase ACL Injury Risk?

The ipsilateral pattern, meaning injuries on the same side as the original pain, points to underlying biomechanical problems rather than overall knee weakness. When patellofemoral pain develops, it typically signals imbalances in how the knee tracks and moves. These same movement dysfunctions that cause anterior knee pain can compromise the stability and control needed to protect the ACL during cutting, pivoting, or sudden directional changes. The data suggests that PFP represents a window into faulty movement patterns that, if left unaddressed, can cascade into more serious ligament injuries.

Young athletes are particularly vulnerable during this window. The research emphasizes that the first year after a PFP diagnosis represents a critical intervention period where targeted rehabilitation could meaningfully alter the injury trajectory .

How to Reduce Your ACL Risk After a Patellofemoral Pain Diagnosis

• Laterality-Specific Neuromuscular Screening: Rather than generic knee exercises, work with a sports medicine professional to identify movement imbalances specific to the affected side, including hip strength, glute activation, and knee alignment patterns.
• Targeted Rehabilitation During Year One: The first 12 months after PFP diagnosis represent the highest-risk window; focus on strengthening the hip and thigh muscles that control knee position and movement quality during dynamic activities.
• Movement Pattern Correction: Address how you run, cut, and pivot by working with a physical therapist to retrain movement mechanics, rather than relying solely on rest, ice, and stretching.

The research team, led by Luke Bunch, a physical therapist and coordinator of the ACL Center of Excellence at Ochsner-Andrews Sports Medicine Institute, presented these findings at the Louisiana Orthopaedic Association 2026 Annual Meeting . The study was conducted by researchers including Jeremy M. Burnham, MD, an orthopedic surgeon and director of sports medicine at the same institution .

"Rather than managing PFP in isolation with ice and rest, the data argues for laterality-specific neuromuscular screening and targeted rehabilitation, particularly for young athletes who may be at elevated ACL risk," the research team noted.

Luke Bunch, PT, DPT, OCS, SCS, Ochsner-Andrews Sports Medicine Institute

What Should Athletes and Patients Do Now?

If you've been diagnosed with patellofemoral pain, the message is clear: don't dismiss it as a minor running injury. Seek evaluation from a sports medicine professional or physical therapist who can assess your movement patterns and identify the specific biomechanical issues contributing to your pain. The goal isn't just to reduce pain in the short term, but to correct the underlying movement dysfunctions that could lead to ACL injury down the road. Early recognition and proactive treatment during the critical first year after diagnosis could meaningfully prevent a cascade of more serious knee injuries .

The research reframes how clinicians and athletes should think about runner's knee. It's not simply a painful nuisance to manage with rest and anti-inflammatory measures. Instead, it's a potential early warning signal that your knee's movement mechanics need attention. By addressing PFP aggressively and specifically during that vulnerable first year, you may be able to avoid the far more serious injury of an ACL tear and the lengthy rehabilitation that follows.