Paul Michelin

Ultrasound and anatomical assessment of the infraspinatus tendon through anterosuperolateral approach.

ObjectivesIn the literature, shoulder ultrasound (US) protocols rely on the widely accepted anatomical concept of the infraspinatus tendon (IST) running parallel and posterior to the supraspinatus tendon (SST). To assess the IST, authors currently recommend placing the transducer posteroinferior to the acromion; however the examination of the anterosuperior part of the IST remains problematic. The aim of our study was to apply recent anatomical knowledge to propose a simple protocol to assess the IST over its entire width including its anterosuperior margin.Materials and methodsSix non-diseased shoulders from four cadavers were assessed in hyperextended internal rotation (HIR) position with US anterosuperolateral approach followed by dissection. Twelve healthy volunteers underwent similar US examination of the shoulder.ResultsThe IST is a thin, wide, strap-like tendon. The HIR position exposed the largest area of IST beyond the acromion; combined anterosuperolateral US approach enabled imaging of the IST over its entire width with transverse and longitudinal views. The anterosuperior margin of the IST was distinguishable from the SST.ConclusionThe anterosuperolateral US approach in HIR position enables an accurate assessment of the IST including the transverse plane. The limit between the SST and IST appears more clearly.Key Points• The hyperextended internal rotation of the shoulder brings the infraspinatus tendon forward.• The infraspinatus tendon is visible with anterosuperolateral ultrasound approach.• The anterosuperior margin of the infraspinatus tendon is visible with this technique.

Posterior C1C2 harms fusion with 3D surgical navigation

Several types of atlantoaxial instability can justify surgical fixation. The instrumented fusion procedure described by Harms with screw fixation of the C1 lateral masses and C2 pedicles is a demanding technique that provides lasting stabilization. However, it has been associated with nerve and vascular complications due to the local anatomical configuration. Surgical navigation systems can help improve the procedures accuracy. We describe a series of 11 cases of C1C2 Harms fusion performed with surgical navigation and intraoperative 3D imaging checks. All procedures were carried out completely with satisfactory implant placement. There were no adverse events related to the procedure during the peri-operative period. No cortical breach was detected using cone-beam CT at the end of the procedure. The technical challenges and risks associated with C1C2 Harms fusion have led to the use of 3D intraoperative imaging systems, when available.

Axillary Sonography of the Shoulder: An Adjunctive Approach: Axillary Sonography of the Shoulder

Sonography of the shoulder is widely used to assess various disorders, including tendinous diseases of the rotator cuff and the long head of the biceps brachii muscle. The shoulder is commonly explored through anterior, superior, and posterior approaches, but the inferior axillary approach is rarely considered in the literature. However, this technique allows the direct visualization of relevant anatomic structures. The aim of this pictorial essay is, first, to technically describe this approach and the normal musculoskeletal sonographic anatomy of the region and, second, to present the sonographic findings of shoulder disorders that may be helpfully explored this technique.

Ultrasound biomechanical anatomy of the soft structures in relation to the ulnar nerve in the cubital tunnel of the elbow

BackgroundChronic ulnar nerve entrapment worsened by elbow flexion is the most common injury, but rare painful conditions may also be related to ulnar nerve instability. The posterior bundle of the medial collateral ligament (pMCL) and the retinaculum, respectively form a soft floor and a ceiling for the cubital tunnel. The aim of our study was to dynamically assess these soft structures of the cubital tunnel focusing on those involved in the biomechanics of the ulnar nerve.MethodsForty healthy volunteers had a bilateral ultrasonography of the cubital tunnel. Elbows were scanned in full extension, 45° and 90°, and maximal passive flexion. Morphological changes of the nerve and related structures were dynamically assessed on transverse views.ResultsBoth the pMCL and the retinaculum tightened with flexion. During elbow flexion, the tightening of the pMCL superficially moved the ulnar nerve remote from the osseous floor of the retroepicondylar groove. A retinaculum was visible in all 69 tunnels with stable nerves (86.3%), tightened in flexion, but absent in 11 tunnels with unstable nerves (13.7%). The retinaculum was fibrous in 60 elbows and muscular in nine, the nine muscular variants did not significantly influence the biomechanics of stable nerves. Stable nerves flattened in late flexion between the tightened pMCL and retinaculum, whereas unstable nerves transiently flattened when translating against the anterior osseous edge of the groove.ConclusionThe retinaculum and the pMCL are key structures in the biomechanics of the ulnar nerve in the cubital tunnel of the elbow.

Familial solitary chondrosarcoma resulting from germline EXT2 mutation

Germline mutations of EXT2, encoding Exostosin Glycosyltransferase 2, are associated with multiple osteochondromas (MO), an autosomal dominant disease characterized by the development of multiple peripheral cartilaginous benign tumors with a weak risk of malignant transformation. We report here a family with a remarkable clinical presentation characterized by the development of isolated chondrosarcomas, mostly located in ribs. Comparative analysis of exomes from two third‐degree affected relatives led us to identify a single common disruptive variation, corresponding to a stop mutation (c.237G > A, p.Trp79*; (NM_000401.3); c.138G > A, p.Trp46*; (NM_207122.1)) within exon 2 of the EXT2 gene. Interestingly, no obvious sign of MO was detected in affected members by radiological examination. This report shows that germline mutations of EXT2 can result, not only in the development of multiple benign osteochondromas, but also in the development of isolated malignant cartilaginous tumors including central tumors, and that the presence of germline EXT2 mutation should be considered in patients suspected to have an inherited predisposition to chondrosarcoma, even in the absence of MO.