Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Chronische zenuwpijn na een operatie aan de knie

\u3cp\u3eBACKGROUND: Chronic knee symptoms after surgery around the knee may be neuropathic. These symptoms are often described after intramedullary osteosynthesis of the lower leg, placement of total knee prosthesis and arthroscopy. This neuropathic pain may be caused by partial damage to the infrapatellar nerve.\u3c/p\u3e\u3cp\u3eCASE DESCRIPTION: An 18-year-old patient had chronic neuropathic symptoms after intramedullary osteosynthesis of the lower leg. The diagnosis was made through physical examination and injection of lidocaine 1%. After surgical removal of the infrapatellar nerve, the patient became symptom-free for a long time.\u3c/p\u3e\u3cp\u3eCONCLUSION: In case of chronic pain around the knee, neuropathic pain resulting from infrapatellar nerve damage should be part of the differential diagnosis. Neurectomy of the patellar nerve is a good treatment if conservative therapy did not lead to improvement of the symptoms.\u3c/p\u3

Complex fractures of the distal radius treated with angular stability plates

Complex fractures of the distal radius are articular lesions and comminuted at the level of the epiphysis and metaphysis. Their treatment is difficult and in most cases surgical. Of all the different osteosynthesis methods available, internal fixation with plate and screws is the most commonly used. In particular, angular stability plates are superior in terms of rigidity and stability to conventional volar and dorsal plates. DVR plate has these mechanical characteristics, and its low profile has reduced frictions with surrounding soft tissues. For these reasons, this device implanted through a single volar approach, can stabilize the majority of volarly and dorsally displaced unstable distal radius fractures. In this study, 48 patients, affected by complex fractures of the distal radius treated with DVR volar plates, were assessed by the Mayo modified wrist score, the Italian version of the disability of the arm, shoulder and hand. The satisfactory results observed confirm the efficacy of this device