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Biomedical subjects

O Paar

Publications and source records attributed to O Paar.

At least 19 recordsLinked to original sources
PubMed2004

[Reconstruction of extensive soft tissue loss by transplantation of dermal and epidermal equivalents].

AIM: The opportunities of autologous dermal and epidermal grafting as starting point for non-invasive reconstruction of extensive soft tissue defects will be demonstrated and discussed. METHODS: Skin biopsies for cell cultivation were taken from patients with extensive acute soft tissue defects of different origin. Cultured autologous fibroblasts grown on three dimensional biocompatible scaffolds made up of benzyl ester of hyaluronan were transplanted as "neo-dermis" on debrided and conditioned wound sites. After incorporation of the dermal equivalents grafting of subconfluent proliferative keratinocytes on hyaluronan based laser perforated membranes was performed. Ten days later a 0.2 mm thin, 1 : 6 meshed autograft to create definite biomechanical stability was overlaid. RESULTS: Grafting of in vitro cultured autologous fibroblasts revealed a good vascularized dermal tissue substitute. After keratinocyte-transfer formation of thin epithelium was visible. Final closure of the defects with aesthetic and normo-elastic tissue properties was achieved after thin mesh-grafting. CONCLUSIONS: Preliminary results seem to be very promising. Clinical follow-up as well as histological and immunohistochemical outcome in the treatment of five extensive soft-tissue defects are discussed. As in all fields of tissue engineering, long-tem studies and cost-benefit analyses are required.

Adult↗
PubMed2002

[Modification of human osteoblasts by various analgesics].

Analgesia plays a major role in the therapy of fractures. This raises the question whether frequently used analgetics as Tramadol and Diclofenac have negative effects on the healing of fractures. Human osteoblasts were isolated from human spongiosa and incubated with Diclofenac, Tramadol and without analgetic substance in an in vitro experiment. After 9 days the absolute number of cells as a marker for proliferation and their mitochondrial activity were quantified. The mitochondrial activity was measured using the metabolisation of XTT (sodium-3'-(1-[phenylamino-carbonyl]-3,4-tetrazolium)-bis(4- methoxy-6-nitro) benzene-sulfonic acid hydrate). Both drugs led to a concentration-dependent decrease of cell proliferation. Tramadol showed a significant effect at a concentration of 20 micrograms/ml, which is much higher than the therapeutical concentration of 0.25 microgram/ml in serum. Diclofenac decreased cell proliferation at a concentration of 6 micrograms/ml, having a therapeutical concentration of 1.5 micrograms/ml in serum. Vitality of cells had constant correlation to absolute number of cells (R = 0.95). Our results don't suggest any negative effects of Tramadol on the osteoblast activities in vitro. Diclofenac significantly decreased the proliferation of human osteoblasts at concentrations probably reachable in vivo. A prolonged healing of fractures under treatment with Diclofenac may be possible in critical situations (pseudarthrosis revision, callus distraction).

Cell Count↗
PubMed2002

[Psychological trauma in trauma medicine--the current status of psychological management of trauma victims in Germany].

A clinically significant amount of accident victims display psychological disorders as a reaction to the trauma. Outcome studies on multiple trauma emphasize that life quality following severe accidental injury is influenced by early diagnosis and treatment of psychic co-morbidity. In a nationwide survey concerning the state of the art in in-patient treatment of injury patients conducted in Germany, every surgical ward was contacted and physicians were asked about their standard procedures of detecting and treating psychotraumatic complications. The results of the survey indicate that surgeons pay close attention to signs of psychological comorbidity and have good basic knowledge of psychotraumatic disorders. Nevertheless, there are structural deficiencies caused by the fact that only a few wards have staff specially trained in psychotraumatological care. Only a minority of patients is treated for psychotraumatic symptoms. In view of the high prevalence rates for psychotraumatic disorders in the aftermath of severe accidental injuries, the article discusses the need for psychic diagnosis and support as well as the necessary cooperative structures required in the model of Integrative Posttraumatic Acute Care.

Germany↗
PubMed2002

[Heparin facilities proliferation of human osteoblasts in vitro].

It is a well-known fact that long-term application of heparin can lead to osteoporosis. To learn more about the mechanisms of heparin-induced osteoporosis, we exposed human osteoblasts in vitro to heparin in various concentrations. We found an increased proliferation rate, especially in concentrations used therapeutically in humans (0.1-0.2 IU/ml). In our experiments fetal calf serum (FCS) was able to heighten the positive effect of heparin, showing a synergism between heparin and FCS.

Cell Count↗
PubMed2001

[Cognitive deficits after polytrauma. Studies of quality of life].

The aim of this study was to quantify and compare the quality of life after multiple trauma for patients with and without posttraumatic cognitive achievement deficits. We examined 173 multiple trauma patients 2-6 years after their injury. The patients were asked to rate their quality of life according to the established measure scales Nottingham Health Profile, Spitzer Index, Everyday Life Questionnaire, to a visual analogue scale and to the new "revised Aachen Longterm Outcome Score" established in our hospital. To evaluate the cognitive achievement of each patient the "Kognitive Minimal Screening" (KMS) was applied. Statistical calculations result cognitive achievement deficits as a highly significant predictor for quality of life after multiple trauma. In spite of this, the craniocerebral trauma is no global predictor of posttraumatic quality of life. These results show that the quality of life after multiple trauma is not only influenced by approved predictors such as injury severity but also significantly by the presence of cognitive achievement deficits. The KMS seems to be an easy test to evaluate those cognitive deficits.

Activities of Daily Living↗
PubMed2001

[Value of human recombinant osteogenetic proteins as bone replacement materials in lumbar spondylodesis. Results of an animal experiment study].

Up to now autologous spongiosa may be considered as the golden standard for the filling up of bone defects. Because of the limited quantity, complications at the extraction place and the increasing problems concerning infections when using homologous spongiosa the development of various bone replacement materials was intensified during the last years. The development of various osteogenetic proteins as well as experimental studies using these proteins represent a main point in science at present. It is expected that these substances will lead to a qualitative improvement and increase of bone healing. In the presented study influence of various osteogenetic substances to bone regeneration was examined at 30 breeding sheep after a ventral spine fusion of the segment L4/L5 by a dorsal approach. Bone defect filling was realized at each 10 animals with autologous spongiosa, Bio-Oss as well as the osteogenetic protein 1 (OP-1). To evaluate the progress and outcome of the segmental fusion during a post-operative period of 24 weeks x-ray controls were performed. In the 24th postoperative week after euthanasia of the experimental animals x-ray controls as well as computed and magnetic resonance tomographies were carried out. The results of 26 experimental animals could be analysed. The results were evaluated according to the criterias of an own score-system. Compared with autologous spongiosa OP-1 as a biomaterial for the fusion of spine-sections led to favorable radiologic results because of higher score values concerning the capability of fusion. Our experiences with Bio-Oss demonstrated lower osteogenetic potency after defect filling with this substance. Therefore we cannot recommend Bio-Oss as filling material for the fusion in spine surgery.

Animals↗
PubMed2001

Aesthetic and functional results of harvesting radial forearm flap, especially with regard to hand function.

There is controversy in the literature regarding donor site morbidity following radial forearm flap harvesting. The aim of this study was to verify possible functional and aesthetic impairments at the donor site. Thirty-five patients who underwent maxillofacial reconstruction using radial forearm flap were asked to give their subjective assessment of the aesthetic outcome at the donor site and of postoperative hand function. They were also examined for trophic status; cold intolerance and tactile sensitivity of split-thickness skin graft, palm and finger pads; grip strength and finger-to-thumb pinch strength; range of movement for the wrist and finger joints; as well as functional hand testing. Slight impairments regarding hand strength and mobility were observed. However, due to their small extent they were of no clinical relevance, as shown by 85.7% of our patients displaying optimal functional hand testing values (80-100%), and 88.6% giving a positive subjective assessment (80-100%) of postoperative vs preoperative hand function. The results show that donor site morbidity following radial forearm flap harvesting is low.

Cold Temperature↗
PubMed2001

[Muscle strength and functional results after surgical repair of Achilles tendon rupture with fibrin gluing].

Treatment of Achilles tendon rupture is discussed controversially. Some trauma centers prefer a conservative therapy. Because of the tendency to a higher rate of reruptures and worse functional results following conservative treatment, operation is the standard therapy of fresh ruptures of the Achilles tendon in Germany. Concerning the functional postoperative outcome, only few studies with uncomparable results were published. To evaluate the functional outcome after Achilles tendon ruptures treated by fibrin gluing, we realized reactive force measurements and motion analysis of 30 patients and 25 healthy test persons. We could observe significant limitations of active range of motion in the ankle joint and a significant deficiency of maximum- and rapid-force. Force deficiency was only detected by the sensitive technical examinations. In daily routine 26 of 30 patients had no limitations. The detected force- and motion-deficiencies were completely compensated. Therefore fibrin gluing of fresh ruptures of the Achilles tendon usually allows postoperatively the same leisure sports activity level as preoperatively. In competitive sporting athletes postoperative loss of performance must be expected.

Achilles Tendon↗
PubMed2000

[Determinants of the global quality of life after polytrauma].

This study investigated multiple trauma patients, who were injured between 1991 and 1995 and treated in our department. The aim of this study was to identify the determinants of quality of life after multiple trauma. From a total of 186 patients 173 (93%) were examined. The patients were asked to rate their quality of life according to the Nottingham Health Profile (NHP) and to a visual analogue scale (VAS). The VAS and the NHP isolated the age of the patients, the duration of artificial respiration, and the duration of rehabilitation as the predictors for a reduced overall quality of life. These results show that quality of life after multiple trauma not only depends on the severity of injury but also on demographic and psychosocial factors.

Adolescent↗
PubMed2000

[Microangiographic evaluation of vascular supply of the medial collateral ligament of the knee joint].

Because the vascularization of ligaments is an important factor in ligament healing we wanted to examine the vascularization status of the medial collateral ligament of the knee. The type of vascularization was examined by microangiographie of 21 postmortem preparations. We could observe a vascularization from the proximal end of the ligament by one or two major vessels in all cases. These vessels were mostly localized in the ventral third of the ligament. From the proximal to the distal part of the ligament we found a decreasing density of blood vessels. We could not observe vessel free ligament areas. Due to this vascularization status we would advise the differentiation of two ligament areas respecting the following therapy. Because of the good vascularization in the proximal part of the ligament we can accept good conditions concerning complete healing after a non-operative treatment and an operative therapy by suture or refixation. In the case of interligamentous and distal ruptures operative reconstruction by sutures often in difficult and a conservative therapy leads to a high rate of poor results. Therefore we advise fibrin bonding in these ligament areas if a surgical procedure is indicated because of the high risk of vessel strangulation after suture.

Angiography↗
PubMed2000

[Treatment outcome after primary hemi-alloarthroplasty in dislocated humeral head fractures].

Humeral head fractures often lead to a high complication rate because of vulnerable vascularization of the humeral head, pretraumatical soft tissue lesions and osteoporotic bone. Compared with open reduction and internal fixation primary hemiarthroplasty seems to be an encouraging alternative treatment in case of dislocated and comminuted fractures. To evaluate our results following primary hemiarthroplasty we examined the outcome of 27 patients treated between November 1993 and May 1997 by primary hemiarthroplasty (15 Neer II, 12 Aequalis) in our institution within two weeks after trauma. The average patient follow-up was 3.5 years. Postoperatively more than 80% of the patients reported no pain. Excellent or good results with abduction over 90 degrees, low or moderate loss of power and low restraint in activities of all day living were achieved in about 50% of patients. The results according to the criteria of the Constant-Score depended on the intensity of the rehabilitation programme with an average outcome of 65 points. Maybe in the future functional results can be improved by a more aggressive rehabilitation and stronger rotator cuff refixation.

Aged↗
PubMed2000

[Diagnosis and therapeutic management following traumatic anterior shoulder dislocation according to extrinsic prognostic factors].

We examined the importance of preoperative CT- and NMR-imaging concerning the detection of a bankart-lesion by a retrospective evaluation of 36 patients with primary traumatic or posttraumatic recurrent shoulder dislocations. Because of unfavourable extrinsic prognostic factors, we advised shoulder arthroscopy and surgical stabilization in all cases. Intraoperatively 35 of 36 patients (97%) presented a bankart-lesion. Preoperatively a bankart-lesion was detected in 32 cases (91%) by CT (n = 29) or NMR (n = 7). We could predict the probability of a bankart-lesion with a high reliability by clinical evaluation alone due to several risk-factors. All patients had at least 2 unfavourable prognostic factors. Under these circumstances we could assume a bankart-lesion with a probability of 97%. Therefore in our opinion preoperative CT or NMR is not advised as standard diagnostic procedure in patients with high-risk of recurrence according to extrinsic prognostic factors. We recommend preoperative CT or NMR when the estimation of prognostic factors concerning the risk of redislocation is doubtful and in case of difficult clinical and ultrasound examination regarding shoulder laxity or rotator cuff lesions.

Adolescent↗
PubMed1999

[Traumatic shoulder dislocation in young athletes--open or arthroscopic stabilization?].

In case of younger patients up to the 30th year with high sports and professional shoulder stress unacceptable recurrence rates up to 49% following arthroscopic stabilization were published. For these patients we recommend open stabilization also in case of primary dislocation. To evaluate our own results following open stabilization with suture-anchors and capsular shift we examined 15 patients with traumatic anterior shoulder dislocation treated between 1.1.1994-31.12.1997 in our clinic retrospectively. Because of the known prognosis factors all patients were classified as high-risk for recurrence. We could examine all patients after an average follow-up of 2.5 years. At the time of reexamination 10 patients had the same level of sports activities as preoperatively. Most patients demonstrated loss of external rotation up to 10 degrees. Compared with the contralateral shoulder 10 patients demonstrated no loss of muscle power. At one patient recurrence without adequate trauma was observed. All other patients demonstrated no clinical symptoms of instability. According to the criteria of the Constant-Score 13 patients achieved excellent or good results. Therefore we recommend open stabilization for young and sporting patients because of the guarantee of a low recurrence rate due to high levels of sports activities. In our opinion in these circumstances arthroscopy is mainly seen as a diagnostic method to evaluate the shoulder pathology before arthrotomy at the same time.

Adolescent↗
PubMed1999

Multiple trauma in children patterns of injury--treatment strategy--outcome.

TOPIC OF THE STUDY: In 1994 more than 50,000 children under 15 years were involved in a road accident in Germany. About one third of them received major injuries and 431 children died. These data obviously show the importance of multiple trauma in children in a developed country. METHODS: Between 1985 and 1990, 64 multi-traumatized children were evaluated after receiving treatment at the Aachen University Hospital. It was possible to evaluate 66% of the patients at the follow-up examination after 1 and 5 years. The results have been measured with the ALOS (Aachen long-term outcome score) and the GOS (Glasgow outcome score) in relation to the degree of trauma. OWN RESULTS: 12.5% died mainly from the effects of a cerebral injury. 25% developed different complications. Again the effects of craniocerebral trauma determined the long-term outcome. All other injuries can be managed by aggressive treatment without major consequences. CONCLUSIONS: In multi-traumatized children, craniocerebral trauma is the key injury regarding both lethality and long-term outcome. Therefore, prevention is of primary importance. Aggressive treatment of thoracic and abdominal trauma can usually help to cure completely these injuries. Especially osteosynthetic procedures, exerting little strain and performed as appropriate for children, have made injuries of the limbs less critical.

Accidents, Traffic↗
PubMed1997

[Ligamentization as an explanation for the stability of periosteal flap repair in the replacement of the fibular ligament system].

The gold standard in the operative treatment of chronic insufficiency of the lateral ligaments of the ankle joint is replacement with a tendon (tenodesis). The disadvantage of this method is limitation of movement. The results of the replacement of ligaments with a periosteal flap are similar to the results after tenodesis, but the rate of complications is significant lower. We investigated the histological changes in periosteal flaps in patients. We saw an alignment of the collagenous fibers in the periosteal flap 8-12 weeks after the operation. The results are statistically significant. The conclusion is that the periosteal flap in the replacement of ligaments changes into a ligament-like structure.

Biopsy↗
PubMed1995

[Injuries in horseback riding--incidence and causes].

This article presents the examination of 78 accidents in horseback riding, referring to their origin and kind of injury. It was found that 76% of all injuries did not occur during the active phase of riding, but in the time just before and right after it. Children without any experience in horseback riding were most susceptible to injuries. Referring to lesions occurring before and after the active phase, the longer extremity was predominantly involved (40%); furthermore, the skull was injured in 18% and the hand in 14% of all lesions. During the active phase of horseback riding, skull injuries increased to 34%. Thoracic and spinal lesions occurred in 15% each. The frequency of all lesions shows a reversed proportional dependence on the amount of experience in this sport. Severity of the accidents increases significantly with increasing demand on performance. In consideration of these studies the thesis can be advanced that coordinated prevention directly before and after the active riding phase can decrease the frequency of all accidents and especially the involvement of the lower extremity and the skull.

Adolescent↗
PubMed1995

[Biomechanics of the knee joint after meniscus resection. Stress analysis of the cadaver knee].

Load bearing analysis has been performed in cadaver knees after different types of inner meniscus resection in extension and in 30 degrees and 60 degrees flexion. Contact areas, mean and maximum pressure differences and load flow changes were measured in the medial and lateral compartment of the knee. The investigation led to following findings: After posterior meniscal tear the resection of the tear with marginal smoothing is followed by a minimum of parameter deviation. All the other types of resection like simple tear resection, partial meniscus resection, amputation of the posterior horn or subtotal resection are accompanied by highly increased deviations of the measured biomechanical parameters. Those are not only observed in the medial part of the knee but also in the lateral compartment. At the medial site a decrease of the load bearing area and the pressure can be registered. In contrast to that there is an increase of these parameters at the lateral site. Consecutive osteoarthritis after medial meniscectomy is therefore interpreted not as a result of increased pressure but of a floating load bearing.

Biomechanical Phenomena↗