Like with most musculoskeletal injuries, a patient history and physical exam performed by a qualified clinician can often lead to an accurate diagnosis for acute hamstring injuries.
A clinician may determine the severity of the hamstring tear (grade 1 to 3) according to pain and physical limitations, including weakness and loss of motion.18,44 These findings may help estimate when a patient can return to activity. 18,44
Hamstring tears can be graded by severity:
- Grade 1 is a strain of the muscle fibers
- Grade 2 is a partial tear of the muscle
- Grade 3 is a complete tear of the muscle
Grade 3 tears are the most severe and can take months to heal.
The diagnostic process will include a patient interview and physical exam and possibly medical imaging:
- A clinician conducting a physical exam may be able to use his or her hands to find where the injury is located; a hamstring tear will often cause a thickening and swelling of soft tissue. While palpation can often pinpoint the injury to either the muscle belly (myotendinous) or the high (proximal) hamstring, the precise location of injury may be difficult to determine without advanced imaging.16-18,27
- The patient may be asked to perform various movements so the practitioner can evaluate strength and range of motion. For example, side-to-side asymmetry of motion, especially with hip flexion with the knee straight, is a common finding on physical examination.35 Resisted knee flexion is also often limited by pain and functional weakness.35 Typically testing will be performed on both sides so that a comparison to the uninjured leg can be made to help gauge the severity of the injury.
- Occasionally, the sciatic nerve, which runs down the back of the thigh, may become irritated or entrapped in healing scar tissue, causing sciatica-like symptoms down the leg.20 In this case, the physician will conduct a thorough musculoskeletal and neurologic examination. This is why it is important to have a physician or qualified clinician perform a complete musculoskeletal and neurologic examination in the setting of hamstring strain.
- X-rays of the hip and knee are often normal (negative) in patients with hamstring injuries unless there is an avulsion of the ischial tuberosity or in pediatric patients, the growth plate. 5,31,35
- Advanced imaging with MRI or dynamic ultrasound imaging (sonography) may be required to determine the level and severity of injury.16,17,45-47
Patient interview. A clinician will ask the patient about how the injury happened, the pattern of pain, and how symptoms affect lifestyle and training.
Physical exam. The clinician will use the physical exam to determine the location and severity of the injury.
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Medical imaging. Medical imaging tests are not needed in all cases. However, if the injury is severe, the diagnosis is uncertain, or a precise location for the injury is needed, imaging tests can be adventageous.16-18,27 Furthermore, in cases where there is significant loss of function, it is important to determine the extent of injury to help guide treatment and possibly predict return to activity.46,50
There are several available imaging techniques for both acute and chronic hamstring injuries.
While MRI has been the gold standard for diagnostic imaging of hamstring injuries, musculoskeletal ultrasound can provide several advantages over X-ray, CT, and MRI tests, including decreased cost, portability, lack of ionizing radiation, and exquisite soft tissue imaging.48,49 Ultrasound imaging also allows medical professionals to dynamically test the tissues—view how the hamstring changes during movement in real time—to rule out other diagnoses or determine severity. In addition, ultrasound imaging been found to be extremely accurate and precise at determining the location and extent of a hamstring injury. 31,45