**5. Clinical examination and prognosis**

Muscle repair is a multistep process which includes myofibers degeneration, regeneration and remodeling by acute inflammatory response (Clever JL, Sakai Y, Wang RA, Schneider DB

The phases of **inflammation** are, in order: organization of the hematoma, necrosis and finally, degeneration of muscle fibers with diapedesis1 of macrophages and phagocytosis of necrotic material Anti-inflammatory drugs which target cyclooxygenase-2 are found able of hindering the skeletal muscle repair process. Muscle regeneration phase can be aided by growth factors, including insulin-like growth factor-1 and nerve growth factor, but these factors are typically short-lived, and thus more effective methods of healing are needed. Skeletal muscle injuries are repaired by muscle cells, myoblasts in condition of oxygenation. The stem cells repair the tissue with paracrine effects, leading to neovascularization of injured site. The *Gharaibeh B'*Group of University of Pittsburgh has found that factor invoked in paracrine action is Angiotensin II, the hormone of blood pressure control.The "LOSARTAN", a drug receptor blocker, in fact reduces fibrotic tissue formation and improves repair of murine injured muscle( Gharaibeh et al. 2012)Other authors hypothesized that a combination of platelet-rich plasma (PRP) injection and oral administration of LOSARTAN, as antifibrotic agent, could enhance muscle healing by stimulating muscle regeneration and angiogenesis and by pre‐

The stage of **regeneration** includes all final phases of the healing process: the production of connective tissue scar and neoangiogenesis, phases very important for the restoration of the muscle visco-elastic properties. The low neovascularization would cause fibrosis, due to local ischemia and low O2 tension. So, in this phase, it's important the utilization of physical

The regeneration process requires the activation of a myogenic stem cells population,, which give rise to proliferating myoblasts. Today we know that repair of muscle takes place with the increase of protein synthesis and activation of satellite cells (stem cells) The satellite cells are quiescent myogenic precursor cells located between the basal membrane and the sarcolemma of myofiber. The adaptation of skeletal muscles to altered use is governed by three major processes: satellite (stem) cell activity, gene transcription, and protein translation. A defect in any of these processes could interfere with muscle maintenance and regeneration. (Shefer G

Myoblasts differentiate and unite together into regenerated myofibers. During the final stages of muscle repair, myofibers remodel to produce mature muscle fibers and recover the con‐

In response to stimuli such as injury or exercise, satellite cells become activated and express myogenic regulatory factors (MRFs, transcription factors of the myogenic lineage including Myf5, MyoD, myogenin, and Mrf4) that proliferate and differentiate into myofibers. The MRF

1 Passage of corpuscular elements of the blood through the capillary walls, typical of inflammatory states.

venting fibrosis in contusion-injured skeletal muscle Terada et al., 2013.

therapies which cause vasodilatation and neovascularization.

In the **remodeling** phase we can observe the "restitutio funtio lesa".

tractile capacity of the injured muscle (Mayssa et al 2012)

2010).

206 Muscle Injuries in Sport Medicine

2012).

We extend these new findings to clinical practice to propose an evidence-based approach for the diagnosis and optimal treatment of skeletal muscle hematomas. Optimal treatment of skeletal muscle injuries start with the right diagnosis (Jarvinen et al., 2005). The clinical diagnosis of a surface hematoma is rather easy thanks to the detection of a bruised area of variable extension depending on the extent of the trauma, contextual to swelling and loss of muscle function. On the other hand, the clinical diagnosis of a deep hematoma may be much more complicated. In this case, the clinical diagnosis must necessarily be supported by the imaging consisting of ultrasonography and / or MR. However, the formulation of a precise and definitive diagnosis in case of an intramuscular hematoma, becomes possible only after 12-72 hours from the detrimental event, since the formation of the hematoma may also appear over three days after the trauma, thereby preventing a possible early diagnosis. A more detailed characterization of the injury can be made using imaging (ultrasound or MRI) repeated at second, seventh and fifteenth day, and certainly at the time of going back to aerobic and anaerobic work (Nanni and Roi, 2013).

A decrease in swelling, a reduction in pain, in the appearance of an area in the first 24 hours post-traumatic and a recovery of muscle function, are indicators of a favorable prognosis. On the contrary, an increase or a persistent swelling after 48-72 hours, an increase in pain, a decrease of peripheral pulses, a prolonged or progressive limitation of joint caused by pain or muscle weakness, a numbness and a sense of / or paresthesia below the area of injury, are all negative prognostic factors.

In any case, there is a better prognosis in the case of intermuscular compared intramuscular hematoma In case of intermuscular hematoma is possible an early mobilization and the patient returns to the sport activity between 1 and 10 weeks. On the contrary, the intramuscular hematoma, especially if is extended, requires greater caution in order to avoid the worrying complications, the myositis ossificans or the fibrosis. For this reason, in the case of intramus‐ cular hematoma, return to sport activity is generally not possible before a period of 10-20 weeks (Ryan, 1999).
