Levon Doursounian

Transcription factor EGR1 directs tendon differentiation and promotes tendon repair

Tendon formation and repair rely on specific combinations of transcription factors, growth factors, and mechanical parameters that regulate the production and spatial organization of type I collagen. Here, we investigated the function of the zinc finger transcription factor EGR1 in tendon formation, healing, and repair using rodent animal models and mesenchymal stem cells (MSCs). Adult tendons of Egr1-/- mice displayed a deficiency in the expression of tendon genes, including Scx, Col1a1, and Col1a2, and were mechanically weaker compared with their WT littermates. EGR1 was recruited to the Col1a1 and Col2a1 promoters in postnatal mouse tendons in vivo. Egr1 was required for the normal gene response following tendon injury in a mouse model of Achilles tendon healing. Forced Egr1 expression programmed MSCs toward the tendon lineage and promoted the formation of in vitro-engineered tendons from MSCs. The application of EGR1-producing MSCs increased the formation of tendon-like tissues in a rat model of Achilles tendon injury. We provide evidence that the ability of EGR1 to promote tendon differentiation is partially mediated by TGF-β2. This study demonstrates EGR1 involvement in adult tendon formation, healing, and repair and identifies Egr1 as a putative target in tendon repair strategies.

Rupture de l'artère axillaire et paralysie du plexus brachial compliquant une luxation glénohumérale antérieure récidivante : à propos d'un cas

The authors report a case of transection of the axillary artery and brachial plexus paralysis following recurrent anterior glenohumeral dislocation. Subsequent vascular reconstruction was performed using a venous interposition graft. The brachial plexus was explored at the same time and found to be in continuity. Neurological recovery was complete within a few months.

Cardiometabolic risk factors in primary centred and rotator cuff-related shoulder osteoarthritis: a comparative study

Background Risk factors for shoulder osteoarthritis (SOA) have been poorly studied. SOA has two anatomical subtypes: primary centred SOA (centred SOA) and rotator cuff-related OA (non-centred SOA). We examined whether cardiometabolic risk factors are preferentially associated with centred than mechanical-induced non-centred SOA. Methods This 2004–2012 retrospective multicentric study included patients with SOA. Data on clinical characteristics, especially cardiometabolic risk factors, were collected. We compared patients with radiographic-centred and non-centred SOA and tested the association between cardiometabolic risk factors and subtypes of SOA. Results We included 147 patients (101 women (68.7%); mean age 75.8±10 years); 99 had centred SOA. As compared with patients with non-centred SOA, those with centred SOA were older (77.5±9 vs 72.4±11 years; p=0.004) with no difference in cardiometabolic disturbances or their accumulation. Multivariable analyses indicated that older age was independently associated with centred SOA (OR 1.06;95% CI 1.02 to 1.1; p=0.004), and cardiovascular diseases were less associated with this subtype (OR 0.27; 95% CI 0.089 to 0.824; p=0.02) than with the non-centred one. Conclusion Cardiometabolic risk factors were not more prevalent with primary centred than rotator cuff-related SOA. They may participate in the pathophysiology of both SOA subtypes through cartilage and tendon disruption.

Avulsion fracture of the extensor carpi radialis longus carpal insertion due to a basketball injury: case report and literature review.

Articular fractures of the base of the 2nd metacarpal involving the extensor carpi radialis longus insertion are unusual and poorly understood. There is no consensus as to how these fractures should be treated. We report the case of a 2nd metacarpal base fracture in a professional basketball player that was treated surgically with open reduction and internal fixation using cannulated screws. The management of this case is compared to similar cases in the literature.

Diagnosis of Ehlers-Danlos syndrome after a first shoulder dislocation

BACKGROUND Shoulder dislocation is often the first symptom of Ehlers-Danlos syndrome (EDS). Whether it occurs in early-onset EDS is unknown. In most cases, surgical failure leads to the diagnosis. We aimed to determine whether clinical symptoms can signal the presence of EDS at a first dislocation. MATERIALS AND METHODS In this retrospective study, we analyzed clinical and radiologic data for 27 patients with EDS and shoulder instability and a control population of 40 consecutive non-EDS patients undergoing surgery for an unstable shoulder. Data were collected on gender, age, single or bilateral disease, general hyperlaxity, shoulder hyperlaxity, number of dislocations or subluxations, nontraumatic onset, and pain specificity. Nerve and vascular injuries, joint disorders, and family history were recorded, and radiologic data were reported. RESULTS Age <14 years, female sex, bilateral disorder, and general hyperlaxity were significantly more frequent in patients with EDS and a first dislocation than in those without EDS. Painless dislocation with pain after dislocation and concomitant nerve injury were more frequent in affected patients, as were hemostasis disorders and a family history of joint hyperlaxity. Bone lesions were not seen on radiographs. Only the hyperlaxity sign (external rotation >85°) did not differ between the groups. CONCLUSION After a first dislocation in a young girl with global hyperlaxity but not necessarily shoulder hyperlaxity, painless atraumatic dislocation with pain after reduction can suggest EDS.

Balloon humeroplasty reconstruction for acute Hill-Sachs injury: A technical note

Posterior Hill-Sachs humeral defects are present in 80% to 100% of cases of anterior shoulder dislocation and are a factor in recurrent instability. Several techniques have been described to fill the defect and avoid recurrence. We developed a percutaneous technique to fill the newly created defect in which a percutaneous balloon, analogous to the one used in vertebral kyphoplasty, is used to reduce the defect, which is then filled with calcium phosphate cement. One patient with an acute anterior dislocation of the shoulder with no previous history was treated using this method. Early imaging results showed adequate reduction of the defect and no cement resorption. The patient was followed for 12 months; he had normal function of the shoulder and no recurrent dislocation. Shoulder computed tomography (CT) arthrography with contrast after 3 months showed an intact capsule and no recurrence of the defect. While this technique is certainly in its infancy, we have demonstrated that emergency reduction of the defect in acute first occurrence anterior shoulder dislocation is feasible, helps to restore normal anatomy of the humeral head and leads to good clinical results. Whether it can improve clinical results and prevent recurrent shoulder dislocation remains to be evaluated.