Implantation Of Endoprostheses Research Articles

Modern Microbiological Methods to Detect Biofilm Formation in Orthopedy and Suggestions for Antibiotic Therapy, with Particular Emphasis on Prosthetic Joint Infection (PJI).

Biofilm formation is a serious problem that relatively often causes complications in orthopedic surgery. Biofilm-forming pathogens invade implanted foreign bodies and surrounding tissues. Such a condition, if not limited at the appropriate time, often requires reoperation. This can be partially prevented by selecting an appropriate prosthesis material that prevents the development of biofilm. There are many modern techniques available to detect the formed biofilm. By applying them we can identify and visualize biofilm-forming microorganisms. The most common etiological factors associated with biofilms in orthopedics are: Staphylococcus aureus, coagulase-negative Staphylococci (CoNS), and Enterococcus spp., whereas Gram-negative bacilli and Candida spp. also deserve attention. It seems crucial, for therapeutic success, to eradicate the microorganisms able to form biofilm after the implantation of endoprostheses. Planning the effective targeted antimicrobial treatment of postoperative infections requires accurate identification of the microorganism responsible for the complications of the procedure. The modern microbiological testing techniques described in this article show the diagnostic options that can be followed to enable the implementation of effective treatment.

RECONSTRUCTION OF THE TROCHANTERIC ZONE IN PRIMARY ARTHROPLASTY OF UNSTABLE PERTROCHANTERIC FRACTURES.

The aim: To justify the concept and features of acetabular reconstruction during primary endoprosthesis for transcatheter fractures from the standpoint of radiological data, biomechanical calculations and intraoperative observations. Materials and methods: A retrospective analysis of the use of primary cement arthroplasty for osteoporotic fractures of the trochanteric zone in 52 elderly and senile patients was conducted. Before implantation of the femoral component, fragments of the proximal metaphysis were fixed with cerclage tightening loops which depended on the type of fracture. For fractures 31-A2.1, 31-A2.2, 31-A2.3, reconstruction of the destroyed trochanteric zone and the walls of the bone marrow canal opening was performed using our own methodology. Finite-element modeling with the SolidWorks program was used to investigate the influence of the reconstruction of the trochanteric zone on the distribution of strain on the bone tissue around the implant under osteopenic conditions and load during single-support standing. Results: Clinical and X-ray results were studied in 39 (74.36%) operated patients within 3 to 33 months. There were no complications associated with recon-struction of the proximal part of the femur and implantation of endoprostheses. Restoration of movements in the hip joint and full loading of the operated limb was allowed the day after surgery, depending on the patients` physical condition. The results of finite-element modeling indicate a significant reduction of the strain on the proximal metaphysis in the zone of predominant destruction of the medial and posterior walls of the bone marrow canal of the trochanteric zone reconstruction and ensuring the stability of the femoral component. Conclusions: Clinical results and biomechanical calculations confirm the possibility and feasibility of using primary arthroplasty in unstable osteoporotic fractures of the trochanteric zone with the aim of early restoration of the support function of the damaged limb in individuals with limited physical capabili¬ties. Reconstruction of the intertrochanteric area with a ring-shaped autograft contributes to the achievement of primary stability of the femoral component, restoration of the total femoral offset and stabilizing function of muscles around the joints.

Biomechanical Characteristics of Light Synthetic Materials for Hernioplasty (Experimental Study)

Importance of the topic. One of the directions of improving hernioplasty efficiency with the use of light synthetic materials is including the strengthening zones in their structure.
 Purpose. To compare functional effectiveness of the light and the light strengthened polypropylene endoprostheses for hernioplasty on the base of studying biomechanical characteristics of anterior abdominal wall tissues after their implantation in experiment.
 Materials and methods. Experimental studies were conducted on 36 rabbits of “chinchilla” breed. All animals were divided into 2 series of experiments. In the first (control) series the light polypropylene endoprosthesis was implanted, while in the second (experimental) series there was used a new cancellated endoprosthesis from monofilamentous polypropylene, consisting of the basic and strengthened zones in the form of horizontally located, alternating with each other monothreads of the higher thickness. Pathomorphological changes and biomechanical properties of the abdominal wall tissues were studied macroscopically in the experiment by implantation of endoprostheses in onlay position on the 7th, 30th and 90th days.
 Results and their discussion. There was proved that in direction of the loop column as well as in the loop row after implantation of the studied materials breaking load increased from the 7th to the 90th day of experiment, that was related to the formation of the connective tissue capsule around materials. The light strengthened endoprosthesis was more durable and stronger in 1,6 times compare to the light analog at all stages of observation. Along the loop column there was no significant difference detected. In both series of experiment in the direction of the loop column as well as in loop row the reduction of sample lengthening took place. Along the loop column indicators of lengthening, characterizing elasticity of the prosthesis aponeurosis, in the series of the light strengthened endoprosthesis were 1,4-1,6 times lower than in its light analog. Along the loop row there was no significant difference of indicators.
 Conclusion. Introduction of the strengthened zones in a light endoprosthesis increases its durability with preservation of the material’s elasticity.

Endoscopic management is the treatment of choice for bile leaks after liver resection

Despite improvements in surgical techniques and postoperative patient care, bile leaks still occur postoperatively in as many as 15% of liver resections (LRs) and are associated with high mortality. There is a paucity of outcome data on endoscopic treatment of complex bile leaks. The aim of this retrospective study was to evaluate the efficacy of interventional endoscopy in the treatment of bile leaks after LR. Retrospective interventional study. Sixty patients with bile leaks after LR were treated endoscopically with or without implantation of endoprostheses by using ERCP. The characteristics of LR, effects of surgical and other nonendoscopic treatment measures, clinical and endoscopic presentation of bile leaks, and outcomes after stent placement were recorded. Main outcome measure was resolution of leakage or termination of unsuccessful endoscopic leakage therapy. The median age of the observed cohort was 58 years. Sixty-five percent of patients had central and 35% peripheral bile leaks; 55% had resection of an entire hepatic lobe, and 45% underwent segmental resection. The overall success rate of endoscopic therapy was 77%. Although endoscopic therapy was performed in all patients with a mean of 2.6 interventions, 28% underwent additional percutaneous drainage. Success of endoscopic treatment was related to stent implantation. Thirteen patients with unsuccessful endoscopic treatment underwent surgical reintervention, and 1 patient died before surgical intervention. No standardized protocol for stent placement due to retrospective nature of the study. Small sample number with uneven distribution of outcome. Endoscopic therapy with sphincterotomy and insertion of endoprostheses is effective, even in large postoperative bile leaks and particularly for leaks proximal to the common hepatic duct. Complete resolution of the leakage often necessitates multiple treatment sessions.

Elbow Reconstruction Following an Extensive Resection of the Proximal Part of the Ulna in a Patient with Ewing Sarcoma: A Case Report.

Malignant bone tumors are usually located in the lower extremities. Malignant bone tumors in the upper extremities, especially in the forearm, are rare1. Current treatment of this type of tumor consists of chemotherapy and limb-sparing, radical resection of the tumor. The most frequently applied reconstructive procedures involve the implantation of endoprostheses, autogenous bone grafts, allografts, and other forms of reconstruction2-6. This case report describes a patient with a tumor of the ulna; the operative treatment and its results are also presented. The patient and his parents were informed that data concerning the case would be submitted for publication, and they provided consent. A seven-year-old boy presented to the hospital emergency department with pain in the left elbow that had been ongoing for several days. Clinical examination revealed left elbow distension, reddening of the skin over the olecranon, and tenderness of this region to palpation. Laboratory tests showed mild elevation of the inflammation indicators, including erythrocyte sedimentation rate, C-reactive protein level, and white blood-cell count. A radiograph of the forearm failed to reveal any pathology. The patient was discharged with recommended antibiotic therapy, and a follow-up visit was scheduled for two weeks later. Two months after the first visit, the patient reported to the Orthopaedic Outpatient Department at the University Children’s Hospital with persistent pain in the left elbow. Clinical examination revealed edema of the entire elbow with mild erythema and tenderness to palpation, especially prominent in the olecranon region. A radiograph of the forearm demonstrated advanced osteolytic lesions within the proximal part of the ulna, with concomitant reactive osteogenesis and a periosteal reaction (Fig. 1). Radiographs also showed a pathological fracture within the involved region of the bone. The radiographs raised unequivocal suspicion of a malignant neoplastic lesion; therefore, the patient was hospitalized for …

Die plastische Versorgung von Weichteildefekten nach Endoprothetik an der unteren Extremität

The implantation of endoprostheses is an established procedure in orthopaedic and trauma surgery. However, the techniques are often associated with a high risk of post-interventional infections and wound healing disorders that can result in loss of the prosthesis or the limb--most likely based on an insufficient debridement and poor soft-tissue coverage. The purpose of this study was to evaluate the efficacy of the coverage methods in our patient population. In the past 10 years 38 patients with exposed knee prostheses and 14 patients following an ankle endoprosthesis were included in this retrospective study over the period from 2001 to 2011. Soft-tissue reconstructions around the knee were mostly performed by unilateral or bilateral gastrocnemius flaps combined with split-skin grafts. One defect was covered with a free flap. 57% of the soft-tissue defects around the ankle are often problematic and were closed by a pedicled peroneus brevis muscle flap and 35% by a free flap (3 with a latissimus dorsi muscle flap, 2 with a free lateral upper arm flap and one with an anterolateral tight flap). In our patient population we achieved stable soft-tissue coverage in most of the cases using the above-mentioned flaps. Due to multiple preexisting comorbidities, it was observed that the course was frequently prolonged and wound healing difficulties occurred. These, however, could be controlled by conservative means or small secondary procedures. A radical debridement and an early appropriate defect coverage of the exposed prosthesis is crucial in the reconstruction process. Through a close interdisciplinary collaboration a stable soft-tissue covering can be achieved. Consequently it is possible to avoid a loss of the endoprosthesis, marked functional deficits or even amputations.

Numerical simulation of strain-adaptive bone remodelling in the ankle joint.

BackgroundThe use of artificial endoprostheses has become a routine procedure for knee and hip joints while ankle arthritis has traditionally been treated by means of arthrodesis. Due to its advantages, the implantation of endoprostheses is constantly increasing. While finite element analyses (FEA) of strain-adaptive bone remodelling have been carried out for the hip joint in previous studies, to our knowledge there are no investigations that have considered remodelling processes of the ankle joint. In order to evaluate and optimise new generation implants of the ankle joint, as well as to gain additional knowledge regarding the biomechanics, strain-adaptive bone remodelling has been calculated separately for the tibia and the talus after providing them with an implant.MethodsFE models of the bone-implant assembly for both the tibia and the talus have been developed. Bone characteristics such as the density distribution have been applied corresponding to CT scans. A force of 5,200 N, which corresponds to the compression force during normal walking of a person with a weight of 100 kg according to Stauffer et al., has been used in the simulation. The bone adaptation law, previously developed by our research team, has been used for the calculation of the remodelling processes.ResultsA total bone mass loss of 2% in the tibia and 13% in the talus was calculated. The greater decline of density in the talus is due to its smaller size compared to the relatively large implant dimensions causing remodelling processes in the whole bone tissue. In the tibia, bone remodelling processes are only calculated in areas adjacent to the implant. Thus, a smaller bone mass loss than in the talus can be expected. There is a high agreement between the simulation results in the distal tibia and the literature regarding.ConclusionsIn this study, strain-adaptive bone remodelling processes are simulated using the FE method. The results contribute to a better understanding of the biomechanical behaviour of the ankle joint and hence are useful for the optimisation of the implant geometry in the future.

Systematic and exclusive use of intravascular ultrasound for endovascular aneurysm repair - the Lausanne experience

Five years of experience with endovascular infrarenal aneurysm repair at our institution is reviewed. Implantation of endoprostheses in 88 patients has been performed by surgeons using exclusively intravascular ultrasound (IVUS) and fluoroscopy. IVUS identified the target site of deployment in all cases. In-hospital morbidity was 22% (19/88). Two percent mortality (2/88) and 5% early conversion (4/88) as a consequence of type I endoleaks were noted only in the first 53 patients with early devices (NS). Early endoleaks were present in 36% (32/88) including twenty-two type I, five type II and five type III endoleaks. Proximal endoleaks were associated with early devices (P<0.001), and technical difficulties with deployment. Tube grafts used in the beginning, performed poorly with 54% (7/13) type I endoleaks. Endoleaks diminished to 10% (9/88) by spontaneous closure and secondary endovascular procedures that were necessary in 24% (21/88) and consisted of coil embolization/cuff extension (9), late conversion (6), and limb recanalization or femoral cross-over bypass (6). Endovascular aneurysm repair using IVUS is a valid alternative technique. Improved devices and systematic use of bifurcated endoprostheses for infrarenal aneurysms reduce the occurrence of type I endoleaks.

Palliative therapy of pancreatic adenocarcinoma

The palliative therapy of pancreatic carcinoma consists of best supportive care (BSC) including nutritional and pain therapy, and antineoplastic remedies. This is complemented by interventional endoscopy aiming to treat obstructive jaundice and/or gastric or duodenal obstruction by implantation of endoprostheses. Pain therapy is standardized for the most part according to the WHO guidelines; nutrition of the cancer patient, however, is sometimes disregarded. For palliative chemotherapy, 5-fluorouracil and gemcitabine can be recommended. Combinations thereof with other cytostatic drugs or radiation are subject to ongoing studies. A variety of novel therapeutic concepts, e.g. immunomodulation or suicide gene therapy, have demonstrated good effects in animal studies. Unfortunately, very few of these have entered clinical studies (phase I and phase II). This will be the focus of future research in this field.

Results of percutaneous implantation of coated vascular prostheses in long-distance femoropopliteal occlusions

Evaluation of primary patency rate, complications and midterm follow-up after implantation of endoprostheses in femoropopliteal occlusions. 25 patients suffering from femoropopliteal occlusion (average length 7 cm) underwent percutaneous femoropopliteal endoprosthesis treatment. A total of 34 endoprostheses were implanted. Clinical and Doppler follow-up was performed after 1, 3, 6 and 9 months. Mean follow-up is 6 months. Percutaneous placement of endoprostheses was successful primarily in 24/25 patients. In one patient an early occlusion of the endoprosthesis occurred, caused by an embolic complication. Primary patency was 64% after 6 months and secondary patency rate was 71%. Severe local pain at the application site and fever was observed in 40% of the patients. The occlusion rate of 36% after 6 months is high. Long-term follow-up must be awaited before a general recommendation can be made. The cause of the local pain and fever in the early postinterventional period remains unclear.

Isokinetic force-velocity curves in patients following implantation of an individual total hip prosthesis.

There are only a few studies which could support conclusions concerning the strength of the muscles surrounding the hip joint and especially concerning the strength relationships following implantation of endoprostheses. The aim of this study was to examine the post-operative course of strength deficits in this musculature compared to clinical parameters. Fifty-eight patients between 30 and 67 years of age, in whom individual total hip prostheses were implanted, were clinically examined prior, 9 weeks and 6 months after surgery. Moreover, the maximum isometric strengths of abductors, flexors, and rotator muscles as well as maximum isokinetic strengths of the extensors and flexor musculature at 60 degrees/s and 120 degrees/s were measured. The flexor and extensor musculature already showed a clear increase in maximum strength after 9 weeks and 6 months. By contrast, the isometric strengths of the rotators increased only slightly, the abductor strength decreased after 9 weeks to below the preoperative baseline level and attained this level again only after 6 months. The clinical parameters Trendelenburg sign, limping, and walking capacity were clearly improved after 6 months, but no correlation to the abductor strength could be demonstrated. It is concluded that limp-free gait can be attained even without maximum strength increase in the abductors, which are important for fluid gait, at least for short distances. The importance of regular training of the rotator and abductor musculature in coxarthrosis is emphasized to delay limitation of movement and decreased strength in the sense of a capsule pattern.

New clinico-pathophysiological studies on the bone cement implantation syndrome.

Implantation of endoprostheses with bone cement is followed by alterations of the circulation. Intoxication, caused by the monomer of bone cement or pulmonary embolism by intramedullary contents constitute the two mostly accepted pathophysiological hypotheses. Because of the lack of pulmonary and circulatory physiological data a clinical decision concerning the value of the hypotheses was not possible until now. Hip prosthesis implantation was analyzed in 15 patients by measuring equipment controlled by an on-line-computer. The device allowed a high rate of data retrieval. The bone cement implantation syndrome reveals itself as cardiorespiratory sequelae of a disseminated pulmonary embolism which is originating in intramedullary contents, squeezed intravasal. Usual prophylactic methods are revisited.