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Biomedical subjects

S Arens

Publications and source records attributed to S Arens.

At least 19 recordsLinked to original sources
PubMed2006

[Oblique osteotomy for post-traumatic fibula incongruity].

BACKGROUND: Injuries of the ankle joint are common and, considering that this joint is highly mechanically stressed, it seems obvious that therapy requires restoring the joint to a physiological, anatomically functional unit. In case of post-traumatic shortening, rotation and talar tilt arthritis may result because of the changed biomechanics. Before this occurs, typical clinical symptoms are recurrent swelling, pain, and limited range of motion, together resulting in reduced mobility and quality of life. With prompt indication and revision lengthening the lateral ankle and thus restoring joint congruity, patient complaints are significantly reduced and the development of advanced arthritis can be avoided. PATIENTS AND METHODS: Within a period of 7 years, 16 patients with post-traumatic shortening of the fibula were treated with oblique osteotomy and lengthening of the fibula at our department. The mean time between trauma and reconstructive surgery was 10 months, and the median follow-up period to clinic and radiological examination was 3.7 years. RESULTS AND CONCLUSION: Comparison of results before and after correction showed significant subjective improvements, and the development or continuation of post-traumatic arthritis could be hindered, of critical importance to which is prompt indication for operative joint correction, because clinical symptoms of advanced osteoarthritis of the ankle joint cannot be expected to improve.

Activities of Daily Living↗
PubMed2006

The undiagnosed Essex-Lopresti injury.

The Essex-Lopresti injury is rare. It consists of fracture of the head of the radius, rupture of the interosseous membrane and disruption of the distal radioulnar joint. The injury is often missed because attention is directed towards the fracture of the head of the radius. We present a series of 12 patients with a mean age of 44.9 years (26 to 54), 11 of whom were treated surgically at a mean of 4.6 months (1 to 16) after injury and the other after 18 years. They were followed up for a mean of 29.2 months (2 to 69). Ten patients had additional injuries to the forearm or wrist, which made diagnosis more difficult. Replacement of the head of the radius was carried out in ten patients and the Sauve-Kapandji procedure in three. Patients were assessed using standard outcome scores. The mean post-operative Disabilities of the Arm, Shoulder and Hand score was 55 (37 to 83), the mean Morrey Elbow Performance score was 72.2 (39 to 92) and the mean Mayo wrist score was 61.3 (35 to 80). The mean grip strength was 68.5% (39.6% to 91.3%) of the unaffected wrist. Most of the patients (10 of 12) were satisfied with their operation and in 11 the pain was relieved. When treating the chronic Essex-Lopresti injury, we recommend accurate realignment of the radius and ulna and replacement of the head of the radius. If this fails a Sauve-Kapandji procedure to arthrodese the distal radioulnar joint should be undertaken to stabilise the forearm while maintaining mobility.

Adult↗
PubMed2004

[Influence of local application of basic fibroblast growth factor on resistance to local infection after standardized closed soft tissue trauma. An experimental study in rats].

The aim of the study was to obtain information on the importance/influence of local application of an angiogenic potent growth factor (bFGF) on local infection resistance after soft tissue trauma.A paired comparison of infection rates was carried out on Sprague-Dawley rats after standardized, closed soft tissue trauma and local, percutaneous bacterial inoculation of different concentrations (2 x 10(4)-2 x 10(7)), whereby the lower leg was treated with 1, 10, and 100 ng bFGF (n=16 each) and without bFGF (n=16). Statistical evaluation of the differences between the infection rates of both groups was performed using the two-sided Fisher's exact test ( p<0.05). For the group without bFGF application, the infection rate was 25%. In the groups with 1, 10, and 100 ng bFGF application, the infection rates were 50%, 69%, and 81%. The difference in the infection rates for the groups in which 10 and 100 ng bFGF were applied was highly significant ( p=0.032/ p=0.004) compared with the group without bFGF. If these initial results are confirmed for other angiogenic potent growth factors, then the local application of growth factors to stimulate wound and bone healing will need to be reconsidered and preceded by a very strict evaluation of the risks and benefits.

Animals↗
PubMed2004

[Animal models of osteomyelitis].

Despite new approaches in biochemical testing, radiologic and nuclear medicine and advances in surgical techniques, the problem of diagnosis and therapy of acute and chronic osteitis has not been finally solved. Clinical research on osteitis is problematic as there are many variables influencing the inflammatory process and a wide spectrum in therapeutic options exists, hampering research under defined conditions. Consequently, there was an early need for animal models. In vivo experimental settings were established to gain reproducible and reliable results under standardized conditions on the pathogenesis and therapy of osteitis. In this article, an overview of the hitherto established experimental animal models and the results of osteitis research on these models is given.

Animals↗
PubMed2004

[Pathophysiology of posttraumatic osteitis].

Over the last few decades, significant reduction of post-traumatic infections could be attained by establishing novel surgical techniques and tactics, by adapting surgical decisions to the risk of infection, by employing chemotherapeutic agents, and by developing new implants. Here a novel understanding of the pathophysiologic mechanisms of post-traumatic and postoperative osteomyelitis were directive. Nevertheless, post-traumatic infections later cause significant physical and economic sequelae. This article sums up the fundamental pathophysiological mechanisms of post-traumatic infection. New ideas about post-traumatic prevention and therapy of osteomyelitis are discussed.

Foreign-Body Reaction↗
PubMed2004

[Principles of surgical therapy concepts for postoperative and chronic osteomyelitis].

Infection of the bone is one of the most serious complications in the field of orthopedic and trauma orthopedic surgery. Sufficient treatment protocols not only contain complex surgical procedures but also sophisticated diagnostic tools, proper use of antibiotics, and intensive physical therapy right from the beginning. Even in light of these advanced treatment protocols, which have great impact on both patients and health care systems, persisting infection and residual functional deficits of the extremities are not rare. In cases of early (acute) infection, the main objective is to avoid chronification by diligent surgical interventions. The surgical principle is the meticulous debridement and lavage of the situs. Revision of only the epifascial layers is as inadequate as the simple reopening of the wound without excision of the whole wound including all tissue layers. In cases of chronic soft tissue and bone infection, radical debridement of all infected and scar tissue is also the basic requirement of treatment. Reconstruction of the soft tissue envelope is done by local or free flap surgery. Because of they are better resistant to infection, musculo(cutaneous)flaps are preferred. Bony reconstruction is done by autologous cancellous bone grafting (partial defects), segment transport (full thickness defects), or freely transplanted vascularized bone grafts (large partial defects). Both soft tissue and osseous reconstruction take a relatively long period of time requiring several operations and periods of hospitalization. These have to be discussed and explained to the patients extensively. If the required amount of resection and the capability of reconstruction do not coincide, the surgeon and the patient have to decide whether restoration of function without definitive infection care, symptomatic infection therapy, or amputation is the most proper treatment option according to the patient's everyday needs and lifestyle. Because each treatment protocol is a composition of orthopedic trauma surgeons, plastic surgeons, radiologists, microbiologists, and physical therapists, reliable cooperation and communication is essential.

Chronic Disease↗
PubMed2004

[Special aspects of implant-associated infection in orthopedic surgery. From the pathophysiology to custom-tailored prevention strategies].

One of the most important risk factors in orthopedic surgery is implant-associated infection. Adhesion and colonization mediated implant infections are extremely resistant to antibiotics and host defences and frequently persist until the biomaterial or foreign body is removed, which is standard therapy. Tissue damage caused by surgery and foreign body implantation increases the susceptibility to infections, activates host defences and stimulates the generation of inflammatory mediators including radicals that are further aggravated by bacterial activity and toxins. Nearly one third of implant-related infections can be prevented by strictly following established infection control guidelines. However, a significant number of implant-associated infections remains. The escape of bacteria from host defence and antibiotic therapy makes the development of infection-resistant materials as anti-microbial drug delivery systems feasible. This concept consists of the sustained delivery of antimicrobial drugs into the local microenvironment of implants avoiding systemic side effects exceeding usual systemic concentrations by magnitudes of order.

Anti-Bacterial Agents↗
PubMed2004

[Infantile spondylolysis with spina bifida occulta in athletes].

Children with evidenced spondylolysis of the lumbar spine should not practice sport with axial compression strain forces or carry out hyperextensional or rotational movements exercises up to the age of eight to ten years, as this could lead to considerable shearing strain to the still cartilaginous disposition of the vertebral arch and therefore initiate an ossification with resulting incomplete closure of the bony elements of the spine (spina bifida occulta). The associated instability of the dorsal vertebral column may yield spondylolisthesis requiring surgical intervention. Competitive sport should be avoided if possible, or carried out in close collaboration with a coach and a physiotherapist under continuous medical supervision with regular radiological monitoring.

Adult↗
PubMed2003

[Fracture dislocation of the elbow involving the coronoid process].

INTRODUCTION: Elbow dislocations are associated with osseus lesions in 30-50%. Integrity of the coronoid process is essential for stability of the elbow joint. METHODS: A retrospective study of 39 patients out of 51 was conducted to evaluate a result of surgical treatment in fracture dislocation of the elbow involving the coronoid process. The patients were followed for an average of 45 months. RESULTS: Operative results were assessed using the Morrey-Score. 3 patients presented an excellent, 19 a good, 14 a moderate and 3 a non satisfactory result. CONCLUSION: Results of operative treatment of fracture dislocation of the elbow are essentially determined by the extent of associated osseus lesions of the radial head and the olecranon. To achieve acceptable functional results early reconstruction and fixation of the coronoid process as well as early mobilisation of the joint is necessary.

Adult↗
PubMed2002

[Pyogenic infection after joint replacement operations: incidence and economic effects].

Infection following arthroplasty is a rare but significant and threatening complication. The incidence is about 2%. Treatment of an infected joint replacement may be demanding, time consuming and expensive. For the treating institution there is a risk of substantial financial losses due to inadequate reimbursement. Calculated on the basis of approximately 150,000 implanted joint protheses/a, an infection rate of 2% and treatment costs of approximately 50,000 [symbol: see text]/infected case the economic burden is an estimated 150 million [symbol: see text]/a in Germany. This amount should justify a sound evaluation of costs related to infection in arthroplasty, which should be the effort of the health insurance organisations. Additionally specific research in the field of infection prevention must be sponsored. The system of reimbursement should be adequately adopted and corrected.

Arthritis, Infectious↗
PubMed2001

Polylactide implants and bacterial contamination: an animal study.

Although bioresorbable aliphatic polyesters derived from lactic acid are now used clinically as sutures, bone-fracture fixation devices and sustained-release drug-delivery systems, very little is known about their behavior in the infected environment. The aim of the present study was to compare the resistance to infection of two polylactide implants with different degradation characteristics, and to evaluate the influence of a bacterial challenge on their mechanical and physicochemical properties. Various quantities of a beta-haemolyzing strain of Staphylococus aureus (V 8189-94) were inoculated into the medullary cavity of rabbit tibiae, and an extruded polylactide rod composed of either P(L)LA (Poly(L-Lactide)) or P(L/DL)LA (Poly(L/DL-Lactide)) was then inserted. Animals were sacrificed four weeks after surgery. The tibiae and implants were removed under sterile conditions and evaluated microbiologically by culturing. The severity of infection was graded according to positive colony-forming units in the bone. The mechanical properties of the retrieved implants were assessed by 4-point bending and shear tests, performed in compliance with the ASTM D790 standard and their physicochemical characteristics also were characterized. P(L)LA and P(L/DL)LA implants were equally resistant to local infection, their mechanical and physicochemical properties being unaffected by bacterial challenge. Hence, once an infection has become established, the release of bactericidal/bacteriostatic by-products during implant degradation does not appear to affect its natural course. The release of bactericidal/bacteriostatic degradation products at the implantation site is unlikely to affect the natural course of an established infection.

Animals↗
PubMed2001

Radiological signs of osteitis around extramedullary metal implants. A radiographic-microbiological correlative analysis in rabbit tibiae after local inoculation of Staphylococcus aureus.

Radiographic changes in the early stages of osteomyelitis may be subtle and, especially after plate osteosynthesis, frequently missed. A previously described experimental model of local bacterial infection was used in an attempt to determine the reliability of specific changes on conventional radiographs for the diagnosis of osteitis after metal-plate implantation and subsequent inoculation of Staphylococcus aureus in rabbit tibiae. Roentgenograms of the treated limbs were evaluated, and seven radiographic parameters, to which numerical scores were assigned, were determined for each bone. Our results substantiate the conclusion that a radiographically verified periosteal reaction is a constant and early skeletal feature of acute osteomyelitis and has the strongest association to the microbiological results (P < 0.05), emphasising its high predictive value. Plate implantation does not notably impede the diagnosis of osteomyelitis. An association between the amount of inoculated bacteria and the extent of radiographic changes could be found. The results of this present study closely resemble those described in man and suggest that this model may be useful for future experimental investigations in determining a score judging the severity of osseous involvement in local bacterial infection after plate osteosynthesis.

Animals↗
PubMed2001

PC-Fix and local infection resistance--influence of implant design on postoperative infection development, clinical and experimental results.

Bacterial infection is still one of the main complications after internal fixation of fractures. The design of implants influences local infection resistance. To reduce the development of infections around implants after internal fixation, the vitality of the bone should be preserved to optimize cellular and humoral host defence mechanisms. For extramedullary fracture fixation, two implant designs are currently in routine use: the Dynamic Compression Plate (DCP) and the Limited Contact Dynamic Compression Plate (LC-DCP). The Point-Contact-Fixator (PC-Fix) is a new design concept based on the philosophy of the LC-DCP and the external fixator. Its function relies on splinting the fragments of a fracture internally with locking bolts rather than with screws that compress the plate to the bone. In this way, the blood supply is not compromised by compression of the periosteum. We investigated the effect of this new design on the incidence of postoperative infection rates in a clinical and an experimental setting. In a prospective multicentre study 1,229 PC-Fixators were used in 896 patients. Of these, 1,172 were available for assessment of infection development. The overall infection rate was 1.1% (13/1,172). The infection rate after open fractures was 1.6% (4/256) and after closed procedures (including closed fractures, osteotomies and non-unions) 1.0% (9/916). These rates are low in comparison to published rates using DCP and LC-DCP. In an experimental study, we compared the infection rates across two groups of rabbits four weeks after fixing either a bacterially contaminated DCP or a PC-Fix to the tibia. Infection rates in the DCP group were significantly higher than in the PC-Fix group: Of the 38 evaluated animals, 12 with a DCP and 5 with a PC-Fix developed local infection (p=0.022). The new PC-Fix design shows low postoperative infection rates in the clinical setting and lower infection rates than the DCP in the experimental setting. The design is an important step in the process of reducing postoperative infection rates.

Adolescent↗
PubMed2000

Striated muscle microvascular response to silver implants: A comparative in vivo study with titanium and stainless steel.

Local microvascular perfusion is the primary line of defense of tissue against microorganisms and plays a considerable role in reparative processes. The impairment of the microcirculation by a biomaterial may therefore have profound consequences. Silver is known to have excellent antimicrobial activity and, although regional and systemic toxic effects have been described, silver is regularly discussed as an implant material in bone surgery. Because little is known about the influence of silver implants on the adjacent host tissue microvasculature, we studied in vivo nutritive perfusion and leukocytic response, and compared these results with those of the conventionally used materials titanium and stainless steel. Using the hamster dorsal skinfold chamber preparation and intravital microscopy, the implantation of a commercially pure silver sample led to a distinct and persistent activation of leukocytes combined with a marked disruption of the microvascular endothelial integrity, massive leukocyte extravasation, and considerable venular dilation. Whereas animals with stainless-steel implants showed a moderate increase in these parameters with a tendency to recuperate, titanium implants caused only a transient increase of leukocyte-endothelial cell interaction within the first 120 min and no significant change in macromolecular leakage, leukocyte extravasation and venular diameter. After 3 days, five of six preparations with silver samples showed severe inflammation and massive edema. Thus, the use of silver as an implant material should be critically judged despite its bactericidal properties. The implant material titanium seems to be well tolerated by the local vascular system and currently represents the golden standard.

Animals↗
PubMed2000

Fluorine-18 fluorodeoxyglucose PET in infectious bone diseases: results of histologically confirmed cases.

The aim of this study was to evaluate the clinical use of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) in acute and chronic osteomyelitis and inflammatory spondylitis. The study population comprised 21 patients suspected of having acute or chronic osteomyelitis or inflammatory spondylitis. Fifteen of these patients subsequently underwent surgery. FDG-PET results were correlated with histopathological findings. The remaining six patients, who underwent conservative therapy, were excluded from any further evaluation due to the lack of histopathological data. The histopathological findings revealed osteomyelitis or inflammatory spondylitis in all 15 patients: seven patients had acute osteomyelitis and eight patients had chronic osteomyelitis or inflammatory spondylitis. FDG-PET yielded 15 true-positive results. The tracer uptake correlated with the histopathological findings in each case. Bone scintigraphy performed in 11 patients yielded ten true-positive results and one false-negative result. Follow-up carried out on two patients revealed normal or clearly reduced tracer uptake, which correlated with a normalisation of clinical data. In early postoperative follow-up it was impossible to differentiate between postsurgical reactive changes and further infection using FDG-PET. It is concluded that acute and chronic osteomyelitis of the peripheral as well as the central skeleton can be detected using FDG-PET. Osteomyelitis can be differentiated from soft tissue infection surrounding the bone. Unlike computed tomography and magnetic resonance imaging, FDG-PET is not affected by metal implants used for fixing fractures. FDG-PET demonstrated promising initial results with respect to treatment monitoring. Nevertheless, in the early postoperative phase FDG-PET seems to be of limited value owing to unspecific tracer uptake.

Adult↗
PubMed1999

Susceptibility to local infection in biological internal fixation. Experimental study of open vs minimally invasive plate osteosynthesis in rabbits.

Resistance to local infection after fracture fixation with plate osteosynthesis may be influenced by the implantation technique. It is known that the extent of the surgical approach to the bone can compromise the local defence capacity. We have investigated susceptibility to infection after a local bacterial challenge in rabbit tibiae using either the open surgical approach for 'biological' internal fixation of standard 2.0 dynamic compression plates or the method of minimally invasive plate osteosynthesis (MIPO), a percutaneous, tunnelling insertion technique preserving the integrity of the overlying soft tissue. After the wounds had been closed, various concentrations of Staphylococcus aureus were injected in the direct vicinity of the implants. The infection rate for the open surgical technique was 38.5% and that for the MIPO technique, 25%. This difference is not statistically significant (P > 0.05) suggesting that resistance to local infection associated with the MIPO method is at least equivalent to the open approach for plate osteosynthesis.

Animals↗