[Posterior Dislocation of the Shoulder with Compression Fracture of the Humeral Head. Our Experience with McLaughlin Procedure and Its Modification]. / Zadní glenohumerální luxace s impresní zlomeninou hlavice. Nase zkusenosti s operací dle McLaughlina a její modifikací.

PURPOSE OF THE STUDY The purpose of this study is to remind of the specific features of diagnosis and therapy of dorsal dislocations of the glenohumeral joint to prevent frequent neglect or misdiagnosis during primary treatment. Also, we strived to present our experience and outcomes of posterior dislocation treatment by McLaughlin procedure and its modified version. MATERIAL AND METHODS We retrospectively evaluated 7 patients who had been treated at our department in the period 2015-2019 by McLaughlin procedure or its modification. The group consisted of 5 men and 2 women aged 33-79 years. In five patients, the dislocation occurred during an epileptic seizure, in two patients during an accident. The patients were treated by McLaughlin procedure or the Neer modification of McLaughlin procedure. The deltoideopectoral surgical approach was always used. Based on the preoperative planning, we decided, or intraoperatively changed our decision, as to whether mere transposition of the subscapularis is satisfactory or whether transposition of the lesser tuberosity to the defect, a bone graft and arthroplasty are necessary. Postoperatively, the operated limb was fixed for 6 weeks in neutral position, which was followed by rehabilitation. RESULTS We evaluated subjective and objective outcomes of the surgery, the radiological finding and in 2 patients also a control CT scan. The function of the shoulder was assessed using the Constant shoulder score and the OSIS scoring system. The resulting score: the mean OSIS was 55.7 points (92.8%) and the mean Constant score was 86.2 points (86.2%), which we regard as a very good result. All patients consider the surgery successful and are satisfied with the outcome. No patient reported recurrent dislocation. DISCUSSION When treating the posterior dislocation of the shoulder, vital is the shoulder reducibility and also the presence or the size of reverse Hill-Sachs defect. The transfer of the subscapularis tendon can be performed as an open procedure or arthroscopically. Inveterate irreducible posterior dislocation of the shoulder is quite a rare diagnosis, which is why even at our department the McLauglin procedure is performed in the order of units per year only. CONCLUSIONS The surgical solution of inveterate posterior dislocation of the shoulder is hardly ever uncomplicated. The reduction alone is often insufficient and some other way of shoulder stabilisation is necessary, often times addressing the humeral head defect. In our to date experience, the McLaughlin procedure or the Neer s modification is an elegant and safe method to treat posterior dislocation with a humeral head defect. The functional outcomes are very good and enable the patients to reengage in everyday activities. Thanks to this procedure shoulder joint arthroplasty can be avoided in younger patients. Nonetheless, in defects that are greater than 50% of the head the replacement is necessary. Due to frequently associated rotator cuff injuries, the most often procedure indicated by us is the reverse total shoulder replacement. Key words: posterior dislocation of the shoulder, reverse Hill-Sachs defect, McLaughlin procedure, Neer s modification.

Implications of the Occurrence of Glitches in Pulsar Free Precession Candidates.

The timing properties of radio pulsars provide a unique probe of neutron star interiors. Recent observations have uncovered quasiperiodicities in the timing and pulse properties of some pulsars, a phenomenon that has often been attributed to free precession of the neutron star, with profound implications for the distribution of superfluidity and superconductivity in the star. We advance this program by developing consistency relations between free precession and pulsars glitches, and we show that there are difficulties in reconciling the two phenomena in some precession candidates. This indicates that the precession model used here needs to be modified or some other phenomenon is at work in producing the quasiperiodicities, or even that there is something missing in terms of our understanding of glitches.

Pulsar discovery by global volunteer computing.

Einstein@Home aggregates the computer power of hundreds of thousands of volunteers from 192 countries to mine large data sets. It has now found a 40.8-hertz isolated pulsar in radio survey data from the Arecibo Observatory taken in February 2007. Additional timing observations indicate that this pulsar is likely a disrupted recycled pulsar. PSR J2007+2722's pulse profile is remarkably wide with emission over almost the entire spin period; the pulsar likely has closely aligned magnetic and spin axes. The massive computing power provided by volunteers should enable many more such discoveries.

[Opening-wedge osteotomy of the proximal tibia]. / Opening wedge osteotomie proximální tibie.

PURPOSE OF THE STUDY: The aim of this study was to evaluate the accuracy of correction and short-term outcomes of treatment by opening-wedge tibial osteotomy with the use of allograft and a modified Puddu plate fixation. MATERIAL: Between February 2001 and March 2003, 33 operations on 30 patients, at an average age of 54 years, with gonarthrosis and varus deformity were evaluated. Grade III arthritis was diagnosed in 24 knees (73 %) and grade II in nine knees (27 %). METHODS: The preoperative planning as well as intraoperative correction were based on the limb mechanical axis, as shown on an X-ray image of the whole lower extemity. Tibial osteotomy was performed from the medial approach and the position was fixed, in contrast to the original method, with an allograft and a T-plate. The corrrection was planned so that the mechanical limb axis should intersect the articular space at 62 % of its length laterally. The limb was postoperatively immobilized for 4 weeks in a knee brace allowing walking. Limited weight bearing was recommended from the third week. The outcome of treatment was evaluated at 11 months of follow-up by the Lysholm scoring system. RESULTS: Correction of the limb mechanical axis involved the axis intersecting the plane of the joint space on average at 60.2 % of its length, as against the planned 62 %; the average deviation from the planned correction was 2.1 degrees. Lysholm scores improved on average by 23 points. Improvement by 20 points was regarded as a good outcome and was achieved in 31 joints (94 %). Two joints (6 %) showed poor outcomes due to associated complications. The complications included a fissure of the lateral tibial plateau in one knee, failed stabilization with subsequent loss of correction and pseudoarthrosis development in one joint, prolonged healing with a partial loss of correction (5 degrees) in one patient, and superficial infection in one patient. DISCUSSION: In patients with knee arthritis and varus deformity, the achievement of optimal correction of the mechanical limb axis is the prerequisite for a long-term good outcome. Optimal correction, as characterized by Puddu, is attained when the mechanical axis intersects the joint space at 62 % of its length laterally. Hernigou et al. define the hip-knee-ankle angle in the range of 183 degrees -186 degrees as an optimal postoperation correction. In our experience, osteotomy combined with our modification of fixation is an exact method for correcting the axis; in addition, it is simple and is associated with a low occurrence of postoperative complications. In view of a possible total knee arthroplasty, there is less disturbance in the tibial plateau-diaphysis alignment and the tibial tuberosity level is preserved. CONCLUSIONS: Opening-wedge tibial osteotomy with the use of a Puddu plate and allograft in our modification is an effective, exact and simple method of correcting the lower extremity axis, and is associated with few complications. We do not recommend this method for interventions planned to achive corrections of more than 16 degrees, because these have a higher occurrence of complications. The use of allograft seems to have good prospects; another option for achieving large correction includes application of an LCP plate.

Are pulsar glitches triggered by a superfluid two-stream instability?

Mature neutron stars are expected to have several superfluid components. Strong evidence for this is provided by the glitches that have been observed in dozens of pulsars. We describe a superfluid analog of the two-stream instability that is well known in plasma physics and provide arguments that this instability is likely to be relevant for neutron stars. This is a new physical mechanism which may play a key role in explaining the glitch mechanism and which could also prove to be relevant in laboratory experiments on various superfluid systems.