Diagnostic Accuracy of Ultrasonography in Patients with Plantar Fasciitis: A Cross-sectional Study

Introduction: Plantar Fasciitis (PFS) is the most well-known cause for plantar heel pain seen predominantly in middle aged women. Imaging findings of Magnetic Resonance Imaging (MRI) is considered to be the gold standard in the diagnosis of PFS, but MRI is expensive. Hence; there is a need to study the accuracy of Ultrasonography (USG), as USG is inexpensive, free of radiation and readily available.

Aim: To evaluate the diagnostic accuracy, sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of ultrasound in comparison with MRI for the diagnosis of PFS, in patients with heel pain.

Materials and Methods: The present cross-sectional study was conducted in the Department of Radiodiagnosis, SRM Medical College and Research Centre, Kattankulathur, Tamil Nadu, India, from December 2019 to July 2021. USG and MRI of foot were performed in 40 patients with heel pain. MRI protocol included three plane Proton Density Fat Saturated (PDFS), T1 sagittal, T2 axial and Short inversion Time Inversion Recovery (STIR) sagittal sequences. USG scans were done in prone position with the patient’s feet dorsiflexed. The Plantar Fascia (PF) thickness was measured in both USG and MRI and association of the ultrasound and MRI measurements of PF thickness was done using Chi-square test.

Results: Mean age of the cohort was 36.83±10.08 years. Out of this subject population, majority were females 29 (72.5%). Nineteen (47.5%) females were overweight i.e., BMI from 25-29.9 kg/m2. The accuracy, sensitivity, specificity, PPV and NPV of plantar fascia thickness of USG as compared to MRI was found to be 80%, 60%, 82.9%, 33.3% and 93.5%, respectively.

Conclusion: Despite MRI being the imaging modality of choice in diagnosing PFS, accuracy of ultrasound was comparable to that of MRI and it can be used as the initial investigation and follow-up.