Evidence — Seen. Strong.

Section 1 · The crisis

What the data says.

250K

ACL tears per year in the U.S., across youth and adult athletes (Datalys Center 2007–2022; AJSM).

2–8×

Female athletes' ACL injury risk multiplier compared to males in the same sport (NCAA Injury Surveillance).

+26%

Increase in youth ACL injury rates since 2007 (National ACL Injury Coalition).

The injury burden is concentrated in cutting and pivoting sports — soccer, basketball, lacrosse, volleyball. The financial cost runs into the billions annually. The career and developmental cost on youth athletes is harder to measure and impossible to overstate.

Sources

Datalys Center for Sports Injury Research and Prevention. NCAA Injury Surveillance Program annual reports, 2007–2022.
American Journal of Sports Medicine. Multiple epidemiology reviews of ACL injury rates in youth sport.
National ACL Injury Coalition. Project Play 2026 Summit briefing.

Section 2 · Why screening works

The patterns are visible before the injury.

Biomechanical research has identified specific movement patterns — knee valgus on landing, asymmetric force production, deceleration mechanics — that correlate with elevated ACL injury risk. These patterns are observable. They are modifiable. They precede the injury by months.

Foundational research

Hewett et al. (2005). "Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes." American Journal of Sports Medicine — the foundational prospective study connecting drop-landing knee valgus to ACL injury.
Padua et al. (2015). "Landing Error Scoring System (LESS) predicts ACL injury risk." Validated population-level screening framework still in use across collegiate and youth programs.
Sugimoto et al. (2015). "Compliance with neuromuscular training reduces ACL injury risk." Systematic review showing that injury reduction effects scale with adherence — making accessibility a determinant of outcomes.
BJSM (2025). Systematic review of neuromuscular training programs: up to 61% reduction in ACL injuries with consistent program adherence.

If a 10-minute screen identifies girls who would benefit from a prevention program — and the program reduces their injury rate by 30 to 61 percent — the public-health math is straightforward.

Section 3 · Phone-based movement analysis

The technology that makes population-scale screening possible.

Until recently, biomechanical screening required laboratory equipment — force plates, motion capture, specialist operators. Population-level use was impossible. Three-dimensional movement analysis from smartphone video has changed the access question.

How it works at the technology layer

Standard smartphone camera captures the athlete's movement at high frame rate.
AI-driven pose estimation reconstructs a 3D biomechanical model from the 2D video — markerless tracking, depth inference, skeletal mapping.
The model returns structured biomechanical metrics: joint angles, asymmetry indices, movement-quality scores.
The triage algorithm consumes the metrics. The athlete and parent never see the underlying technical data.

Validation

Smartphone motion analysis has been validated against laboratory motion capture in multiple peer-reviewed studies. The technology has been used in research across major universities and elite professional sport. The limitation has historically been not accuracy but distribution. The 100,000 Girls campaign is built to solve the distribution problem.

Specific technology partnerships and validation studies are referenced internally per IP disclosure boundaries. The methodology stack is reviewable by clinical advisory partners and institutional collaborators on request.

Section 4 · The national coalition

The 100,000 Girls campaign is not a single organization.

The National ACL Injury Coalition convened the framework. The campaign aligns the parties that were already working on the same problem from different angles.

Convening partners

National ACL Injury Coalition

Aspen Institute · Project Play

U.S. Soccer · Recognize to Recover

Hospital for Special Surgery

NWSL Provider Network

Clinton Foundation · Too Small to Fail

Public-policy momentum

California SCR-151 — state senate concurrent resolution acknowledging the ACL injury rate in youth female athletes and calling for screening access.
The ACL Pledge — a multi-organization commitment to support population-level prevention.
U.S. Soccer's Recognize to Recover — federation-level guidance integrating prevention practices into youth coaching.

Section 5 · Our approach

Designed for population coverage, not individual precision.

A clinical screening protocol that is 95% accurate but unavailable to 99% of youth athletes is not the same as a triage protocol that is 80% accurate and accessible to anyone with a phone. The 100,000 Girls campaign optimizes for the second.

Calibration principles

Sensitivity over specificity. False negatives are worse than false positives. When the screen is ambiguous, it errs toward recommending evaluation.
Population framing. The score is built for triage at the population level — to identify which girls would benefit from clinical attention or a tailored prevention program. It is not a substitute for individual clinical judgment.
Clinical advisory input. Threshold calibration involves sports medicine physicians and sports physical therapists. Tiers are reviewed quarterly as data accumulates.
Validation through outcomes. The campaign tracks de-identified outcome data so the screen calibration improves with use.

What the screen is: a triage tool that identifies movement patterns associated with elevated injury risk and recommends the appropriate next step. What it is not: a diagnostic medical device, a substitute for clinical evaluation, or a predictor of individual injury events.

Twenty years
of research.
One screening.

What the data says.

Sources

The patterns are visible before the injury.

Foundational research

The technology that makes population-scale screening possible.

How it works at the technology layer

Validation

The 100,000 Girls campaign is not a single organization.

Convening partners

Public-policy momentum

Designed for population coverage, not individual precision.

Calibration principles

Ready to be part of the cohort?

Twenty yearsof research.One screening.

What the data says.

Sources

The patterns are visible before the injury.

Foundational research

The technology that makes population-scale screening possible.

How it works at the technology layer

Validation

The 100,000 Girls campaign is not a single organization.

Convening partners

Public-policy momentum

Designed for population coverage, not individual precision.

Calibration principles

Ready to be part of the cohort?

Twenty years
of research.
One screening.