The archetype of myotendinous injuries is the tear of the myotendinous junction of the indirect head of the rectus femoris muscle (Fig. The archetype of myofascial injuries is the myofascial tear of the medial head of gastrocnemius muscle and soleus muscle (Fig. Myofascial and myotendinous injuries are secondary to acute trauma, but after recovery recurrences are common with minor trauma. MRI findings are similar in both cases with the loss of the normal architecture of the muscle and fasciae, abnormal heterogenous intermediate signal intensity on T1w and T2w sequences, and inconstant collections of fluid and/or blood. These injuries mostly involve shear stress with the contraction of different muscles or contraction of the muscle fibers of the same muscle in divergent directions causing excessive stress on the fasciae in between. In adults, muscle injuries tend to occur at muscle weak areas including the interface between the muscle and the epimysium (myofascial injuries) and the interface between the muscle and the tendon (myotendinous injuries). 3).įull size image Myofascial and myotendinous injuries MLL is more frequently located at the interface between the hypodermic fat and the deep peripheral fascia, but it can also occur in the hypodermic fat along the fascia superficialis ( stratum membranosum) (Fig. Typical aspect of MLL is a fusiform or ovoid fluid collection located superficially to the deep peripheral fascia with low signal intensity on T1-weighted (T1w) images and high signal intensity on T2-weighted (T2w) images (Fig. MLL occurs most frequently at the lateral aspect of the thigh or around the knee in areas prone to shearing stress during accident. This cleavage causes disruption of small vessels that cross the fascia and accumulation of lymph or blood into the perifascial plane with possible debris from fat necrosis and blood clots. MLL is secondary to the delamination along fascial planes after high-energy trauma with excessive shearing and subsequent separation of the subcutaneous soft tissues from the underlying deep fascia. Morel-Lavallée lesion (MLL) is a post-traumatic complication of the subcutaneous soft tissues after acute trauma. Traumatic lesions of the fasciae usually occur at the interfaces between the different components of the fascial system or at physiological defects of the fasciae which constitute weakness points from a mechanical point of view.

This mismatch may originate from repeated microtraumas (overuse), acute injuries, or a combination of both. “Deep intermuscular fascia” to describe the deep intermuscular septa located deep to the deep peripheral fascia and separating muscles and muscle groups from each other.Īs bones or tendons, fasciae are injured when a mismatch exists between the forces placed on them and their ability to resist such forces. “Deep peripheral fascia” to designate the layer of connective tissue located at the interface between the hypodermis and the connective tissue surrounding the muscles (epimysium) “Fascia superficialis” to designate the complex formed by the layer of connective tissue located immediately deep to the dermis ( stratum membranosum) and its attachments to the dermis ( retinacula cutis superficialis) and to the deeper components of the fascial system ( retinacula cutis profondis) The following terms will be used to describe the different components of the fascial system (Fig. Therefore, the current pictorial review aims to focus on traumatic disorders, infectious diseases, and neoplastic diseases involving the fasciae of the musculoskeletal system and their appearance at MRI. Anyway, the fascial system may also be involved in localized disorders. In a previous article, we detailed how MRI patterns of involvement of the fasciae in systemic autoimmune diseases reflect the fascial anatomy. Despite its presence everywhere throughout the body, the fascial system has received little attention in the imaging literature as it is regarded as a network of inert membranes barely involved by abnormal conditions.

Compartments of leg radiology