Dynamics of epileptiform activity in mouse hippocampal slices

Increase of the extracellular K +  concentration mediates seizure-like synchronized activities in vitro and was proposed to be one of the main factors underlying epileptogenesis in some types of seizures in vivo. While underlying biophysical mechanisms clearly involve cell depolarization and overall increase in excitability, it remains unknown what qualitative changes of the spatio-temporal network dynamics occur after extracellular K +  increase. In this study, we used multi-electrode recordings from mouse hippocampal slices to explore changes of the network activity during progressive increase of the extracellular K +  concentration. Our analysis revealed complex spatio-temporal evolution of epileptiform activity and demonstrated a sequence of state transitions from relatively simple network bursts into complex bursting, with multiple synchronized events within each burst. We describe these transitions as qualitative changes of the state attractors, constructed from experimental data, mediated by elevation of extracellular K +  concentration

Total elbow arthroplasty in traumatic and post-traumatic bone defects

Total elbow arthroplasty is currently most commonly carried out due to acute trauma or post-traumatic conditions. Bone defects are often present and must be considered in the (pre-)operative workup. The use of semi-constrained prostheses with a systematic cementing technique through a triceps-on approach leads to satisfying clinical results, however, the outcome is worse when compared with rheumatic patients. Primary total elbow arthroplasty for complex distal humerus fractures in the elderly patient or secondary implantation following failed conservative treatment or osteosynthesis represent possible indications for (postaEuro)traumatic joint replacement. The condyles do not have to be reconstructed and the humerus can be shortened by 2-3 cm without sacrificing the functionality of the extensor apparatus. In the case of post-traumatic joint destruction and pronounced chronic instability following complex fractures of the proximal forearm - especially following terrible triad or Monteggia-like injuries - total elbow arthroplasty can be considered as a treatment option. The extensor apparatus must be reconstructed, and the implantation of the prosthesis must thus be combined with plate osteosynthesis of the ulna - if necessary. Chronic deformity should only be corrected as much as needed in order to avoid early aseptic loosening due to increased shearing forces and polyethylene wear. Massive bone loss is problematic and can be compensated with allografts or tumor prostheses. The results of these salvage procedures are less predictable, and complication rates increase significantly

Chronic ligamentous instability of the elbow

Chronic ligamentous instability of the elbow is an important pathology as it is accompanied with pronounced dysfunction. Moreover, it represents an established risk factor for the development of osteoarthritis. Posterolateral rotatory instability (PLRI) caused by insufficiency of the lateral collateral ligament (LCL) is the most common type of chronic elbow instability and is usually a sequel of traumatic elbow dislocation. Chronic overload can lead to insufficiency of the ulnar collateral ligament (UCL) with subsequent valgus instability, especially in overhead athletes. Subjective instability and recurrent elbow dislocations are not always the main symptoms but elbow instability is instead often characterized by pain and secondary joint stiffness. Many clinical tests are available yet eliciting them can be difficult and inconclusive. A drop sign on lateral radiographs as well as the detection of collateral ligament injuries and joint incongruity on MRI scans can support the suspected diagnosis. In some cases, instability can only be verified by diagnostic arthroscopy. Reconstruction of the lateral ulnar collateral ligament (LUCL) for treatment of PLRI generally leads to good clinical results, yet recurrent instability remains an issue and has been reported in 8 % of cases. UCL reconstruction for chronic valgus instability leads to a return-to-sports rate of about 86 % in the overhead athlete. Ulnar neuropathy, which is seen in approximately 6 % of patients, represents the most common complication. On the rare occasion of multidirectional instability, the box-loop technique can be used for simultaneous reconstruction of the LUCL and UCL with a circumferential graft. 15 cases with promising results have been reported in literature thus far