Reprint of: The Deadman Theory of Suture Anchors: Observations Along a South Texas Fence Line

Suture anchors are being increasingly reported as a means of fixation of torn rotator cuff tendons to bone. The author has developed a mechanical model for the suture anchor–rotator cuff construct based on an analogy to the deadman system used to stabilize a corner fence post. Using this model, one can demonstrate a mechanically favorable angle of insertion of the suture anchor (θ₁) such that the anchor's pullout strength is increased at low angles of θ₁. In addition, the angle that the suture makes with the direction of pull of the rotator cuff (θ₂) has a direct effect on tension in the suture. A low angle of θ₂ minimizes the total tension in the suture, thereby minimizing the chance of suture breakage.     

Neue minimal-invasive Implantate zur Therapie von distalen Radiusfrakturen

Recently minimally invasive implants, such as DNP® (dorsal nail plate), XSCREW®, TargonDR® and Micronail® have been developed for internal fixation of the distal radius. These implants are thought to allow stable fixation of some fracture types by minimizing soft tissue compromise. Few clinical and biomechanical studies have been performed to determine whether the new devices are useful alternatives in fixation of distal radius fractures. Initial clinical results are promising for some devices. In own biomechanical studies we found that fixation of unstable extra-articular distal radius fractures with XSCREW® provides more stability than fixation with DNP® and that fixation with TargonDR® provides more stability than with a 2.4 mm LCP®.     

Distal humerus fractures in the elderly: osteosynthesis or endoprosthesis? Review of the literature

Fractures of the distal humerus in adults are rare but challenging for the orthopaedic trauma surgeon. The bimodal distribution reflects the trauma mechanism. While distal humerus fractures are caused by high-energy traumata in young male adults, a fall from a standing height is the most common reason for humerus fractures among elderly females. As a rule, fractures of the distal humerus are treated surgically. In young patients, open reduction and internal fixation (ORIF) with anatomic locking plates are the gold standard. In elderly patients, reconstruction is not always possible, and total elbow arthroplasty (TEA) becomes necessary. The present article provides an overview of the current diagnostic and treatment recommendations. The current literature is reviewed and the results discussed.     

Networks in signal transduction: the role of adaptor proteins in platelet activation

In multicellular organisms, the translation of externally applied signals into appropriate cellular responses is mediated by a multitude of complex intracellular signalling cascades. The accurate function of these signalling pathways is based on the sound interaction of proteins of different categories such as transmembrane receptors, protein kinases, protein phosphatases and g-proteins in three-dimensional signalling complexes. During the past 10 years it has became evident that a new class of proteins termed adaptor proteins is indispensable for the assembly of these intracellular signalling scaffolds. The primary function of adaptor proteins is to mediate protein–protein and protein–lipid interactions and thus to integrate receptor-mediated signals at the intracellular level and to couple signalling receptors to cytosolic signalling pathways. In order to perform this task, adapter proteins are equipped with particular protein–protein and/or protein–lipid interaction modules allowing them to communicate with other signalling proteins. While the essential function of adaptor proteins is clearly established in a variety of cell types (e.g. immune cells), the current knowledge about their role in platelet activation is still in the beginning. Numerous adaptor proteins have been shown to be expressed in platelets and many of them seem to be involved in the assembly of signalling complexes after engagement of platelet receptors such as the collagen receptor glycoprotein VI (GPVI), thrombin receptors, integrin receptors and the GP Ib receptor. This review will focus on the functional role of the most extensively studied adaptor proteins during platelet activation.