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Relationship Between Ankle Plantar Flexion Angle and Tendon Gap in Achilles Tendon Rupture: A Prospective Study Using
Gregory Waryasz1,2, Atta Taseh1, Nour Nassour1
1Foot and Ankle Research and Innovation Lab - FARIL, Department of Orthopaedic Surgery, Mass General Brigham, Harvard Medical School, Boston, USA.
Cureus
|June 29, 2026
Summary
Ankle angle measurement can help screen for Achilles tendon ruptures (ATR), even without advanced imaging. A specific angle threshold shows promise for detecting ATR and estimating tendon gaps.
Area of Science:
- Orthopedics
- Diagnostic Imaging
- Musculoskeletal Research
Background:
- Achilles tendon rupture (ATR) diagnosis and timely intervention are crucial for minimizing complications, disabilities, and healthcare costs.
- The size of the ATR gap significantly influences treatment decisions, including surgical versus non-surgical approaches.
- Accurate and accessible diagnostic methods for ATR are needed, particularly in resource-limited settings.
Purpose of the Study:
- To evaluate the correlation between ankle angle in 90-degree knee flexion and the size of the Achilles tendon gap in patients with ATR.
- To determine if ankle angle measurement can reliably detect ATR and estimate the tendon gap.
- To explore the potential of ankle angle measurement as a screening tool for ATR.
Main Methods:
- Prospective study involving 47 patients with acute ATR.
- Pre-operative assessment using portable handheld ultrasound to measure tendon gap at various foot positions and ankle angles.
- Spearman's correlation and receiver operating characteristic (ROC) analysis were employed to analyze data and identify optimal thresholds.
Main Results:
- No significant correlation was found between Achilles tendon gap size and ankle angle measurements, or between PROMs and these measurements.
- A significant difference in plantar flexion angles was observed between injured (median 99.4°) and uninjured (median 110.6°) ankles (p < 0.001).
- An optimal ankle angle threshold of 104.75° demonstrated 83% sensitivity and 78% specificity for distinguishing ATR.
Conclusions:
- Ankle angle measurement, particularly the identified threshold, may serve as a valuable adjunct for screening Achilles tendon ruptures, especially where advanced imaging is unavailable.
- This method shows potential for assisting in clinical evaluation and diagnosis of ATR.
- Further research is warranted to validate the combined use of ankle angle measurement and portable handheld ultrasound as a cost-effective diagnostic approach for ATR.
