Physical Examination for Suspected Hamstring Tear
Perform a focused physical examination using at least two of the following four clinical tests: palpation for a gap/defect, assessment of ankle plantar flexion strength, the Thompson test (calf squeeze), and passive ankle dorsiflexion with gentle manipulation—combining multiple tests increases diagnostic accuracy over any single finding. 1, 2, 3
Essential History Components
- Mechanism of injury: Forceful eccentric contraction during sprinting, kicking, or sudden deceleration 4
- Location of pain: Proximal (ischial tuberosity), muscle belly, or distal insertion 4
- Onset: Acute versus chronic presentation 2
- Functional limitations: Difficulty with walking, running, or sitting 2, 3
Physical Examination Maneuvers
High-Yield Clinical Tests
Palpation for defect/gap: Direct palpation of the posterior thigh to identify loss of muscle contour or palpable discontinuity 1, 2
Manual muscle testing: Assess hamstring strength with resisted knee flexion—weakness indicates injury severity 2, 5
Active hamstring test at 30° knee flexion (A-30): Patient actively flexes knee to 30° against resistance while prone—sensitivity 73%, specificity 97% 3
Active hamstring test at 90° knee flexion (A-90): Patient actively flexes knee to 90° against resistance while prone—sensitivity 62%, specificity 97% 3
Combining A-30 and A-90 tests yields the highest diagnostic accuracy: sensitivity 84%, specificity 97%, with a positive likelihood ratio of 26.86 3
Long stride heel strike (LSHS) test: Patient performs exaggerated stride with heel strike—sensitivity 55%, specificity 73% 3
Additional Examination Elements
Inspection: Look for ecchymosis, swelling, and asymmetry in muscle contours 4, 2
Gait assessment: Observe for antalgic gait patterns and stride length asymmetry 2
Range of motion testing: Assess both active and passive knee flexion/extension and hip flexion with knee extended (straight leg raise) 2, 5
Referred pain assessment: Evaluate for sciatic nerve involvement, particularly with proximal hamstring injuries 3
Initial Imaging Work-Up
MRI without IV contrast is the gold standard imaging modality for suspected hamstring tears and should be obtained within 3 days post-injury. 6, 4, 2
MRI Advantages
- 100% sensitivity for detecting proximal hamstring avulsions 6
- Classifies location, extent, degree (partial versus complete), and chronicity 6
- Guides treatment decisions: Particularly useful for acute proximal hamstring tendon avulsions where surgical repair may be indicated 6
- Prognostic value: Injury grade, tear length on MRI, and MRI-negative injuries predict recovery time 2
Ultrasound Limitations
Ultrasound has insufficient evidence as the primary imaging modality for hamstring tears—it detected only 58.3% of proximal hamstring avulsions compared to MRI's 100% detection rate 6
When MRI is Not Required
Most muscle belly hamstring injuries do not require MRI in the acute setting if clinical examination clearly indicates a minor strain without significant functional impairment 6
Common Pitfalls to Avoid
Do not rely on a single clinical test: Combining multiple examination findings significantly improves diagnostic accuracy over isolated tests 7, 3
Do not delay MRI beyond 3 days post-injury: Early imaging optimizes diagnostic accuracy and treatment planning 2
Do not miss sciatic nerve involvement: Approximately 52% of proximal hamstring tears have associated sciatic nerve symptoms—assess for radicular pain and neurological deficits 3
Do not substitute ultrasound for MRI in proximal injuries: The marked difference in sensitivity (58.3% vs 100%) makes ultrasound inadequate for ruling out complete avulsions 6