Ultrasound as a predictor of time-loss injury for the patellar tendon, Achilles tendon and plantar fascia

Key points

1. 01Athletes with a pre-season ultrasound abnormality were 9 times (patellar tendon), 19 times (Achilles tendon), and 21 times (plantar fascia) more likely to sustain a time-loss injury than those without abnormalities.
2. 02Ultrasound abnormalities were present in 36.6% of patellar tendons, 7.5% of Achilles tendons, and 2.8% of plantar fasciae; injury rates were 3.3%, 1.6%, and 0.7% respectively.
3. 03A normal pre-season ultrasound was highly reassuring, with negative predictive values above 99% for all three structures.
4. 04Ultrasound sensitivity was superior to both prior injury history and current pain as screening tools across all three structures.
5. 05Even asymptomatic athletes with ultrasound abnormalities showed significantly elevated injury risk, reinforcing the value of structural imaging over symptom-based screening.

How it was conducted

Design

Multi-institutional prospective observational cohort study over 3 years (2021-2023)

Participants

695 athlete scans (538 distinct athletes) from 18 sports across 3 NCAA Division I institutions; 61.1% female, mean age 20.0 years, mean BMI 23.1 kg/m2

Exposure

Pre-season ultrasound evaluation of bilateral patellar tendons, Achilles tendons, and plantar fasciae assessing thickening, hypoechogenicity, and neovascularization

Comparison

Ultrasound abnormality vs. self-reported prior injury vs. pain at time of scan as predictors of injury

Primary outcome

Time-loss injury (development of tendon/fascia pain with tenderness and load-related pain causing loss of at least one practice or competition)

Analysis

Generalized linear model with cluster-robust variance and Cox proportional hazards model, adjusting for prior injury and pain at time of scan

What they found

• Sonographic abnormalities identified in 498 (36.6%) patellar tendons, 104 (7.5%) Achilles tendons, and 39 (2.8%) plantar fasciae.
• Time-loss injury occurred in 3.3% (44 injuries) of patellar tendons, 1.6% (22 injuries) of Achilles tendons, and 0.7% (9 injuries) of plantar fasciae.
• Adjusted relative risk (aRR) of injury with ultrasound abnormality: patellar tendon aRR 8.9 (95% CI 3.7, 21.4), Achilles tendon aRR 18.8 (95% CI 7.2, 48.8), plantar fascia aRR 21.0 (95% CI 6.4, 68.1); all p < 0.001.
• Cox proportional hazards model: hazard ratio for patellar tendon HR 8.2 (95% CI 3.3, 20.5, p < 0.001), Achilles tendon HR 13.3 (95% CI 5.2, 34.1, p < 0.001), plantar fascia HR 17.2 (95% CI 5.1, 58.2, p < 0.001).
• In asymptomatic athletes (no pain at scan), ultrasound abnormalities remained significantly associated with injury: patellar tendon aRR 10.7 (95% CI 4.1, 27.8, p < 0.001), Achilles tendon aRR 19.2 (95% CI 6.6, 55.7, p < 0.001), plantar fascia aRR 13.3 (95% CI 1.4, 104.8, p = 0.025).
• Ultrasound sensitivity for injury prediction: patellar tendon 86.5% (95% CI 74.2, 94.4), Achilles tendon 68.0% (95% CI 46.5, 85.1), plantar fascia 55.6% (95% CI 21.2, 86.3) - all higher than sensitivity of prior injury or pain at time of scan.
• Specificity of ultrasound: patellar tendon 65.4% (95% CI 62.7, 67.9), Achilles tendon 93.6% (95% CI 92.2, 94.8), plantar fascia 97.5% (95% CI 96.6, 98.3).
• Negative predictive value of ultrasound: patellar tendon 99.2% (95% CI 98.3, 99.7), Achilles tendon 99.4% (95% CI 98.8, 99.7), plantar fascia 99.7% (95% CI 99.2, 99.9).
• Positive predictive values were low across all three structures and all three screening tools, indicating that most athletes with any positive screen did not go on to develop an injury.
• Inter-rater reliability for ultrasound video review was near-perfect (kappa values ranging from 0.947 to 1.000).

Limitations

• Sports were unequally represented (e.g., Men's Basketball 20.1%, Gymnastics 3.9%), limiting sport-specific conclusions.
• Ultrasound findings were recorded as present or absent rather than by specific morphologic type, preventing identification of which abnormality subtypes carry highest risk.
• Injury was classified as yes or no; duration of time-loss was not adequately captured, so minor and severe injuries were grouped together.
• Relatively few injury cases in the plantar fascia (0.7%) resulted in wide confidence intervals and potential sparse data bias; findings should be interpreted with caution in other populations such as adolescents or older athletes.

Why it matters

For patients

Athletes with a normal pre-season ultrasound can be reassured they are at very low risk of a tendon or fascia injury that season, while those with abnormalities should be monitored closely and may benefit from targeted preventive rehabilitation.

For clinicians

Pre-season ultrasound screening of the patellar tendon, Achilles tendon, and plantar fascia outperforms history of prior injury and current pain in identifying collegiate athletes at elevated risk for time-loss injury, supporting its use in pre-participation evaluations.

For readers

This is the largest prospective study of its kind, providing robust evidence that structural ultrasound abnormalities independently predict tendon and fascia injuries in collegiate athletes, but interventional trials are still needed to determine whether preventive programs can reduce this risk.