Tendon Transfer Surgery: Focus on…

Median and Ulnar nerve palsy is a devastating condition that compromise hand function.

A procedure of tendon transfer may be helpful to restore the movements by linking palsy muscles to other muscles able to contract. Scientific discoveries and technological innovations have profoundly changed this kind of surgery; studies on sarcomeres, for example, changed the concept of tensioning. To date we know that muscle strength and its contraction capacity depends on many factors (not only tensioning) such as sarcomeres length, cellular cytoskeleton and extracellular matrix composition: all of these factors interact together and in a ways not still fully understood, determining the complex concept of “movement.” Technology made possible the production of smaller and more complex prostheses so to open new frontiers for modulation of the tendon length during grasping. These devices, currently studied on computer models, on cadaver or on animals, behaved great impetus to research but are still not suitable for implantation in humans.

Challenges are still numerous: for example obtain more biocompatible implantable device, find new surgical approach, new ways to obtain better results for this kind of patients.     

Bleeding diverticulosis in patients on oral anticoagulants

Seven of eighty-three patients (8 per cent) hospitalized between 1966 and 1972 because of bleeding diverticulosis were taking oral anticoagulants for six months to ten years prior to admission. The age range of the patients was fifty to ninety-two years with a mean of seventy-two. Anticoagulation was indicated in these patients for prophylaxis of thromboembolic disorders. Five patients with an admission prothrombin time of less than 25 per cent of control each required 2 units or more of blood. All patients were treated successfully by discontinuation of warfarin sodium therapy, blood transfusions, and parenteral administration of vitamin K. Severe bleeding from diverticulosis may occur in patients on oral anticoagulant therapy; however, these patients respond well to conservative methods.     

Hemodialysis without anticoagulants: efficiency and hemostatic aspects

In 29 patients with high risk of bleeding, 111 hemodialyses have been performed without heparin (WHD) or other anticoagulants. The same patients were switched to low dose heparin dialysis (LDHD) as soon as the bleeding risk had ceased. The dialyzer had to be changed in 11 and the drip chamber in 20 WHDs because of partial clotting. This phenomenon did not occur during LDHD. The comparative efficiencies of the two techniques were evaluated by measuring the urea and creatinine clearances of the dialyzers. No significant difference between LDHD and WHD clearances was observed. In 7 of 29 patients, hemostasis variables were studied before, during and after both modes of treatment. Fibrinogen, platelet count, antithrombin III and prothrombin time did not differ with the different dialysis procedures. During dialysis, platelet factor 4 (PF4) levels were significantly higher than baseline values (P less than 0.01), with no difference between WHD and LDHD. Plasma fibrinopeptide A (FPA) levels remained normal during LDHD, but significantly increased during WHD (P less than 0.001). Our data indicate that WHD is feasible, with a low risk of extravascular coagulation. The bleeding risk is not increased during or after dialysis, and the danger of intravascular coagulation is low as confirmed by the isolated elevation of FPA plasma levels, unaccompanied by changes in other variables.     

Whole blood thrombin: development of a process for intra-operative production of human thrombin

Thrombin-based clotting agents currently used for topical hemostasis with absorbable sponges, fibrin sealants, and platelet gels are primarily derived from bovine or pooled human plasma sources. Autologous thrombin has important safety advantages in that it does not carry the same safety concerns as pooled plasma-derived products and it avoids exposure to risks associated with bovine-derived proteins. The goal of our research was to develop a rapid, reliable, and simple to perform process to generate autologous human thrombin in the intraoperative setting, from patient whole blood as the starting source material. Using whole blood instead of plasma as the starting material, it is possible to avoid the inherent delay in thrombin availability associated with a primary step of plasma isolation. In this study, we varied several key processing parameters to maximize thrombin production, reproducibility and stability. Autologous thrombin production was generated using a dedicated, single use disposable with a sterile reagent. The disposable consists of a tubular reaction chamber containing glass microsphere beads to activate the alternative pathway of the coagulation cascade. At the end of the process, thrombin-activated serum was harvested from the reaction chamber. The average activity of the thrombin produced at room temperature by this system was 82.8 +/- 15.9 IU/mL. The total processing time was < 30 minutes. The system was compatible with Anticoagulant Citrate Dextrose-Solution A (ACD-A) (8%-12%). The average volume of thrombin harvested from each aliquot of blood was 7.0 +/- 0.3 mL, and the stability of thrombin was observed to be temperature dependent, with cold storage better preserving thrombin activity. Clot times with platelet concentrates at 1:4.3 and 1:11 ratios (thrombin to platelet concentrate) were < 10 and 20 seconds, respectively. A process for the preparation of thrombin from whole blood, under conditions compatible with the resources of an operating room, has been developed. The device is simple to use, requires 30 minutes, and can consistently produce thrombin solutions that achieve rapid clotting of platelet concentrates, plasma, and fibrinogen concentrates even when mixed at thrombin to blood product ratios of 1:11.     

Posterior Cruciate Ligament: Focus on Conflicting Issues

There is little consensus on how to optimally reconstruct the posterior cruciate ligament (PCL) and the natural history of injured PCL is also unclear. The graft material (autograft vs. allograft), the type of tibial fixation (tibial inlay vs. transtibial tunnel), the femoral tunnel position within the femoral footprint (isometric, central, or eccentric), and the number of bundles in the reconstruction (1 bundle vs. 2 bundles) are among the many decisions that a surgeon must make in a PCL reconstruction. In addition, there is a paucity of information on rehabilitation after reconstruction of the PCL and posterolateral structures. This article focused on the conflicting issues regarding the PCL, and the scientific rationales behind some critical points are discussed.     

Long-term management of an implantable left ventricular assist device using low molecular weight heparin and antiplatelet therapy: a possible alternative to oral anticoagulants

Between January 2004 and December 2005, out of 14 patients with decompensated heart failure who were treated with an INCOR left ventricular assist device (Berlin Heart AG, Berlin, Germany), 10 patients were kept on a long-term regime of low molecular weight heparin (LMWH) and antiplatelet therapy. The treatment objective was bridge-to-transplantation. All patients received LMWH in therapeutic doses according to body weight, in combination with daily aspirin 160 mg, clopidogrel 75 mg, and three times dipyridamole 75 mg. Effectiveness of the low molecular weight regime was monitored through measurement of antifactor Xa activity (base and peak levels). Antiplatelet therapy was monitored through weekly platelet function tests. Within this group of 10 patients, six patients successfully received transplants and four patients died, the latest death after 405 days of INCOR support. Causes of death were sepsis, intestinal hemorrhage, acute right ventricular failure, and one major stroke. Long-term management of INCOR assist devices using a combination of LMWH and antiplatelet therapy is feasible. This treatment strategy can serve as an alternative to oral anticoagulants.