Skeletal muscle repair in a rat muscle injury model: the role of growth hormone (GH) injection.

OBJECTIVE: Muscle injury tends to heal with incomplete functional recovery. Among the growth factors released in the physio-pathological response of muscle lesion, the Insulin-like Growth-Factor-1 (IGF-1) results in an engine factor of the reparation program. The therapeutic use of growth factors has been exploited to improve healing. As IGF-1 is a primary mediator of the effects of growth hormone (GH), we exploited its systemic administration to muscle recovery in a rat model of muscle injury. MATERIALS AND METHODS: Monolateral lesion of the longissimus dorsi muscle of rats was performed. Animals were divided into 5 groups: four groups for histological studies and serum hormone dosage, whilst the fifth group represented the uninjured control. Rat GH was intraperitoneally administered after 24h from the surgical lesion at three different concentrations (0.1, 0.2, 0.4 mg/kg). At 3 days from surgery, immunohistochemical and histological analyses evaluated the expression of MyoD and Myogenin, and the presence of neovascularization and inflammation, respectively. After 2 months, we analyzed the presence of muscle regeneration and fibrosis. RESULTS: The treatment with GH resulted in a significant increase in neovascularization and Myogenin expression at 24h from injury in comparison with the control. This suggested speed up biological recovery times. After two-months, a dose-dependent increase of the connective component was observed. CONCLUSIONS: The potential effect of GH on muscle repair and regeneration, through the activation of satellite cells already demonstrated in vitro, was confirmed in this in vivo experimental approach. This study sheds light on the role of growth factors in damage repair mechanisms to find an appropriate biological treatment for muscle injury.

Distal-third diaphyseal fractures of the humerus: choice of approach and surgical treatment.

PURPOSE: Distal-third diaphyseal fractures of the humerus are often hard to treat due to location and pattern of the fractures, radial nerve injury, and quality of bone and age of patients. The aim of this retrospective study is to propose the best approach and the best surgical technique according to the pattern of extra-articular fracture of the distal humerus. METHODS: We have treated 37 fractures of the distal humerus between January 2010 and July 2015 classified according to the AO classification. There were 2 open fractures. We treated all fractures with open reduction and internal fixation with plates and screws. In 20 cases, we performed a posterior midline triceps-splitting approach, with patients in prone decubitus position; in 2 cases, the triceps-splitting approach with the patients in supine decubitus position; in 3 cases, the olecranon osteotomy approach in prone decubitus position; and in 12 cases, the lateral approach in supine decubitus position. RESULTS: Thirty cases had a medium follow-up of 6 months. We observe 2 post-operative radial nerve palsies healed in 5 months and 2 cases of non-union. The average time to union of remaining cases was 16 weeks (range 12-24). Elbow motility was complete in 25 cases, in 4 cases there was an extension loss of 5°, and in one case there was an extension loss of 10°. CONCLUSIONS: The use of plates allows an anatomical fracture reduction, a better control of alignment of humerus and, with a rigid fixation, an early elbow mobilization. The best approach and the best surgical technique depend on the pattern of the fracture of distal humerus.

EFFECT OF PLATELET RICH PLASMA CONCENTRATION ON SKELETAL MUSCLE REGENERATION: AN EXPERIMENTAL STUDY.

Skeletal muscle injuries are common causes of severe long-term pain and physical disability, accounting for up to 55% of all sports injuries. The phases of the healing processes after direct or indirect muscle injury are complex but clearly defined and include well-coordinated steps: degeneration, inflammation, regeneration, and fibrosis. Despite this frequent occurrence and the presence of a body of data on the pathophysiology of muscle injuries, none of the current treatment strategies have shown to be really effective in strictly controlled trials. Platelet-rich plasma (PRP) is a promising alternative approach based on the ability of autologous growth factors (GFs) to accelerate tissue healing, improve muscular regeneration, increase neovascularization and reduce fibrosis. The present study is focused on the use of different concentrations of PRP as a source of GFs. Unilateral muscle lesions were created on the longissimus dorsi muscle of Wistar rats. Twenty-four h after surgical trauma, the lesion was filled with an intramuscular injection of PRP at 2 different concentrations. A group of rats were left untreated (controls). Animals were sacrificed at 3, 15 and 60 days from surgery. Histological, immunohistochemical and histomorphometric analyses were performed to evaluate muscle regeneration, neovascularization, fibrosis and inflammation. The PRP-treated muscles showed better muscle regeneration, more neovascularization and a slight reduction of fibrosis compared with the control muscles in a dose dependent manner. However, further studies also assessing pain and functional recovery are scheduled.

Platelet rich fibrin matrix effects on skeletal muscle lesions: an experimental study.

Even though muscle injuries are very common, few scientific data on their effective treatment exist. Growth Factors (GFs) may have a role in accelerating muscle repair processes and a currently available strategy for their delivery into the lesion site is the use of autologous platelet-rich plasma (PRP). The present study is focused on the use of Platelet Rich Fibrin Matrix (PRFM), as a source of GFs. Bilateral muscular lesions were created on the longissimus dorsi muscle of Wistar rats. One side of the lesion was filled with a PRFM while the contralateral was left untreated (controls). Animals were sacrificed at 5, 10, 40 and 60 days from surgery. Histological, immunohistochemical and histomorphometric analyses were performed to evaluate muscle regeneration, neovascularization, fibrosis and inflammation. The presence of metaplasia zones, calcifications and heterotopic ossification were also assessed. PRFM treated muscles exhibited an improved muscular regeneration, an increase in neovascularization, and a slight reduction of fibrosis compared with controls. No differences were detected for inflammation. Metaplasia, ossification and heterotopic calcification were not detected. This preliminary morphological experimental study shows that PRFM use can improve muscle regeneration and long-term vascularization. Since autologous blood products are safe, PRFM may be a useful and handy product in clinical treatment of muscle injuries.