The biceps femoris is the most commonly injured hamstring muscle and the semitendinosus is the second most commonly injured. Although hamstring injuries often involve one muscle injured proximally, multiple muscles were involved in 33% of athletes (5/15) and the injuries were distal in 40% of athletes (6/15). All intramuscular injuries occurred at the musculotendinous junction, either at the ends of the muscle or within the muscle belly.

FSE-Cube has similar diagnostic performance as a routine MR imaging protocol for detecting cartilage lesions, cruciate ligament tears, collateral ligament tears, meniscal tears, and bone marrow edema lesions within the knee joint at 3.0 T.

Previously described MR imaging criteria for OCD instability have high specificity for adult but not juvenile lesions of the knee.

Magnetic resonance (MR) imaging is currently the modality of choice for detecting meniscal injuries and planning subsequent treatment. A thorough understanding of the imaging protocols, normal meniscal anatomy, surrounding anatomic structures, and anatomic variants and pitfalls is critical to ensure diagnostic accuracy and prevent unnecessary surgery. High-spatial-resolution imaging of the meniscus can be performed using fast spin-echo and three-dimensional MR imaging sequences. Normal anatomic structures that can mimic a tear include the meniscal ligament, meniscofemoral ligaments, popliteomeniscal fascicles, and meniscomeniscal ligament. Anatomic variants and pitfalls that can mimic a tear include discoid meniscus, meniscal flounce, a meniscal ossicle, and chondrocalcinosis. When a meniscal tear is identified, accurate description and classification of the tear pattern can guide the referring clinician in patient education and surgical planning. For example, longitudinal tears are often amenable to repair, whereas horizontal and radial tears may require partial meniscectomy. Tear patterns include horizontal, longitudinal, radial, root, complex, displaced, and bucket-handle tears. Occasionally, meniscal tears can be difficult to detect at imaging; however, secondary indirect signs, such as a parameniscal cyst, meniscal extrusion, or linear subchondral bone marrow edema, should increase the radiologist's suspicion for an underlying tear. Awareness of common diagnostic errors can ensure accurate diagnosis of meniscal tears. Online supplemental material is available for this article.

Magnetic resonance imaging of the knees of 98 consecutive patients with clinically diagnosed anterior cruciate ligament injuries revealed 47 patients (48%) with focal signal abnormalities consistent with the diagnosis of a "bone bruise." Seventy-one percent of the magnetic resonance images taken within 6 weeks of injury demonstrated a bone bruise, whereas no scans done longer than 6 weeks after injury showed a bruise (P < 0.0001). Also significant was the tendency for lesions to be located in the lateral compartment (P < 0.0001). In the sagittal plane, lesions were most likely to be in the middle third of the lateral femoral condyle and the posterior third of the lateral tibial plateau (P < 0.0001). In 31 patients evaluated arthroscopically, there was no correlation between the presence or location of a bone bruise and articular alterations or meniscal tears observed at surgery.