(Scientific Session) Diagnosing Hamstring Strains Using Shear Wave Elastography

Background and/or Objectives: Hamstring injury diagnoses are often based on clinical assumptions rather than confirmation with the diagnostic imaging gold standard, MRI, which is expensive and time consuming. A more affordable and accessible diagnostic tool is needed to enhance diagnostic accuracy, treatment planning and patient outcomes. Thus, using ultrasound shear wave elastography, we compared tissue stiffness at a site of MRI-confirmed hamstring strain with that of healthy controls to test the hypothesis that stiffness differs when strain is present.

Design: Feasibility cross-sectional study of participants with and without hamstring injury.

Setting: Research hospital

Participants: Ten limbs in five healthy female controls (30.4±6.6 years, 69.5±6.6 kg, 163.6±3.3 cm) and both affected and unaffected limbs in a symptomatic female (57.4 years, 79.2 kg, 165.1 cm) were included in the analysis. We acquired data using Samsung’s WS80A Ultrasound with CA1-7A (curved array) transducer and Philip’s 3T Ingenia Elition MRI.

Interventions: Not applicable.

Main Outcome Measures: Elastography measures were acquired from six regions of a single image of semitendinosus in each limb, producing a single average value. For the patient, measures were acquired 1-week post-strain diagnosis and 6-months post-symptom resolution.

Results: MRI confirmed semitendinosus strain of the affected limb. No strains/tears were detected in unaffected limbs, nor in the affected limb at follow-up. Stiffness was 2.46±0.45 m/s in controls and 2.46 m/s in the patient’s unaffected semitendinosus. The semitendinosus strain location demonstrated greater stiffness (3.52 m/s, 2.4 standard deviations from normative average), which dropped to a normative value at follow-up (2.51 m/s). Power analysis (α=0.05, power=80%) revealed a difference of 11% could be found with cohort sizes of 20.

Conclusions: The site of hamstring strain demonstrated clinically relevant increased stiffness ( < 2% chance of being normative). While this sample size is too small to provide a statistically significant conclusion, it does demonstrate the feasibility of a larger study and the potential promise of shear wave elastography to detect hamstring strains.