Biomedical subjects

J Raunest

Publications and source records attributed to J Raunest.

At least 19 recordsLinked to original sources

PubMed2002

[Treatment of spinal fracture in ankylosing spondylitis].

Clinical guidelines for the treatment of vertebral fractures associated with ankylosing spondylitis are derived from case reports and a review of literature. The coincidence of paravertebral calcifications and fracture formations leads to problems in the establishment of a proper initial diagnosis. Therefore computed tomography and magnetic resonance imaging have to be employed to define the extent of fracture and the presence of spinal lesions. As a rule vertebral fractures based upon spondylitic alterations are extremely unstable and tend to secondary dislocation with a high risk of spinal cord injuries. Operative osteosynthesis is the method of choice in the fracture treatment. A successful stabilization requires an extended spondylodesis comprising at least five vertebral segments by a dorsal or a combined ventral instrumentation.

Adult↗

PubMed2001

[Morbidity and mortality in para-articular femoral fractures in advanced age. Results of a prospective study].

UNLABELLED: This study was designed to determine risk factors and individual dispositions associated with morbidity and mortality in the operative treatment of hip fractures in elderly patients. PATIENTS AND METHODS: In a prospective clinical trial, a consecutive series of 278 patients (mean age: 78.7 +/- 6.2 years) with a hip fracture treated by internal fixation or arthroalloplasty was recorded prospectively concerning preexistent diseases and risk factors. Based upon a multivariate analysis the data were related to perioperative complications and mortality. A follow-up during the first postoperative year was performed to determine mortality rate and causes of deaths. Polymorbidity within the meaning of 3 preexistent diseases was present in 117 cases; a solitary disease was found in 25 patients. Only 19 patients were without significant risks representing a comorbidity of 93.2%. In 64.4% diseases of the cardiovascular system were detected followed by diabetes mellitus (21.9%) and diseases of the respiratory tract (20.1%). RESULTS: In the postoperative course systemic complications were observed in 118 patients indicating a general morbidity of 42.4%. According to the preexistent diseases recorded, cardiovascular complications (25.5%), obstructive ventilatory diseases (10.1%) and pneumonias (12.2%) were the most common complications. During hospital stay 21 patients died (mortality: 7.6%). A total of 76 patients died during the first postoperative year corresponding to a mortality rate of 27.3%. Postoperative complications were observed in patients with polymorbidity at 68.4% which differs significantly with the morbidity of low-risk patients at 23.6% (p < 0.001). Multivariate analysis revealed a combination of polymorbidity and age beyond 78 years as significant risk factors towards morbidity and mortality. In detail, a prevalence of cardiovascular insufficiency, pulmonary disease and disturbance of renal function was found to be a significant disposition. CONCLUSIONS: During the preoperative course high risk patients should be identified according to the data presented above in order to take all measures necessary in critical care during the perioperative period. Furthermore, the results underline the importance of an early operative treatment within a posttraumatic period of 12-24 hours. Concerning the method of fracture stabilization procedures allowing a primary full loading should be favoured with regard to early rehabilitation.

Aged↗

PubMed1998

Proprioception of the cruciate ligaments: receptor mapping in an animal model.

Ten anterior and posterior cruciate ligaments (ACL and PCL) harvested from adult sheep were investigated under light microscopy for data on the frequency and localisation of neural structures. Serial sections of 25 microns thickness were stained with a modified gold chloride technique. Receptors were classified according to their histological structure. Topographic distribution and frequency within the ligament texture were determined with the help of computerized image analysis. Three distinct neural structures could be identified: Ruffini endings, Ruffini corpuscles of the Golgi tendon organ-like type and Pacinian corpuscles. Golgi tendon organs were not found. In total, 274 and 238 neural structures were present in the 10 ACL and 10 PCL, respectively. Pacinian receptors were the most common structures, with a mean frequency of 13.6 +/- 5.3 (ACL) and 12.4 +/- 5.1 (PCL), followed by Ruffini endings with 8.9 +/- 3.2 (ACL) and 7.8 +/- 2.9 (PCL), whereas Ruffini corpuscles had the lowest frequency with a mean value of 4.9 +/- 2.1 (ACL) and 3.4 +/- 1.1 (PCL). The majority of the neural structures were located in the subsynovial sheath or closely associated with endotenon structures. The tibial and femoral insertion areas had a significantly increased receptor density compared with the midpart of the ACL and PCL (P < 0.001), where only 19.3% and 23.7% of the receptors were located. These results emphasise the complex sensory structure of the cruciate ligaments and provide a valid morphological basis for further neurophysiological investigations.

Animals↗

PubMed1998

[Local surgical measures in chronic wounds].

The treatment of chronic wounds is initiated by resection of gangrenous tissue, drainage of abscess formations, and--if necessary--primary resection of necrotic bone and joint structures in the phalanxes. The restoration of arterial blood perfusion in the periphery is a central part of wound management. Several surgical procedures such as necrosectomy, topical application of antiseptic solutions, and hydrocolloid wound dressings serve to create well-vascularized granulative tissue. The application of vacuum occlusive dressings promotes the proliferation of fibroblasts that result in a dense granulative tissue. In the majority of cases, wound closure can be performed by suture traction or with the help of autologous skin grafts.

Abscess↗

PubMed1996

Geometric properties of the fractured tibia stabilized by unreamed interlocking nail: development of a three-dimensional finite element model.

Based upon magnetic resonance scans of five human tibiae a three-dimensional finite element model using eight nodal isoparametric elements was developed to analyze the biomechanical properties of fracture fixation by an unreamed interlocking nail. Tension phenomena and bone implant translations occurring in the borderlines of the fracture zone, bone-implant interface, and the fixation site of the interlocking screws were analyzed with the help of link elements. The proximal fracture segment was fixed with a link element so as to produce exclusively translatory shifts corresponding to the vector of the load applied. Under condition of static load F = 500 N or axial torsion MT = 15 Nm the biomechanical properties of a nailed horizontal fracture (42-A3), a three fragment lesion (42-B2), and a comminuted midshaft fracture (42-C3) were evaluated. On condition of axial load maximum dislocations of 0.1549 mm are induced in the direction of the x-axis due to the asymmetric geometry of the human tibia which promotes medially directed translations. Independent from the fracture type present a homogenous tension profile was calculated for the whole tibia diaphysis with a sigmaEQV ranging from 24.18 to 121.14 MPa due to the relative low elastic modulus of the cortical bone compared to material characteristics of the implant. However, application of a torsional moment MT = 15 Nm induces significantly increased tension maxima in the nail-interlocking screw interface with a sigmaEQV = 7, 626 MPa. Maximum translatory movements ux = 12.59 mm and uy = 23.53 mm in the x and y plane indicate that these load conditions bear a high risk of an implant failure.

Biomechanical Phenomena↗

PubMed1996

Proprioceptive mechanisms in the cruciate ligaments: an electromyographic study on reflex activity in the thigh muscles.

The hypothesis of a proprioceptive mechanism arising from mechanoreceptors in the cruciate ligaments and with efferences to the thigh muscles is investigated in an animal model. Electromyographic (EMG) studies of the quadriceps and hamstrings muscles were performed in six sheep anesthetized by intravenous injection of chloralose on applying static and dynamic shear forces to isolated fascicle bundles in the anterior (ACL) and posterior (PCL) cruciate ligaments at 200 to 500 N and 50 to 200 N/sec, respectively. With the help of an external fixator, the knee joint position was varied at 25 to 150 degrees. The relative preload of the anteromedial and posterolateral fascicles in the ACL and the anterior and posterior fascicles in the PCL induced by variation of the joint angle was measured with the help of strain gages. By static and dynamic loading of the anteromedial group of the ACL, EMG activity in the hamstrings increases significantly to 159 +/- 22 and 257 +/- 46 microV seconds, respectively (p < 0.001), with a simultaneous suppression of the quadriceps activity. Static and dynamic loading of the posterolateral ACL group results in a significant excitation of the quadriceps with mean potentials of 142 +/- 29 and 173 +/- 23 microV seconds, respectively (p < 0.001). Mechanical shear applied both to the anterior and posterior fascicles of the PCL induces a significant activation of the ipsilateral quadriceps muscles with a simultaneous inhibition of the hamstrings (p < 0.001). The quality of mechanical loading, i.e., static or dynamic shear, determines the degree of muscular recruitment significantly (p < 0.01). The joint angle contributes to a modulation in the quantitative EMG excitation. Linear regression analysis of the integrated EMG potential values and the amount of passive preload induced by the respective joint position results in a close correlation (r = + 0.78 to + 0.86). The results lead to the conclusion that a proprioceptive mechanism exists that arises from the cruciate ligaments and influences the tone in the thigh muscles. The degree of muscle excitation on mechanical ligament loading is modulated by the amount of preload in the ACL and PCL and the quality of load applied.

Animals↗

PubMed1996

[Laser-assisted induction of arthrosis].

In a controlled experimental trial the induction of gonarthrosis following laser-assisted meniscectomy was assessed. A XeCl excimer laser (lambda = 308 nm, pulsewidth 20 ns, repetition rate 10-70 Hz, radiant exposure 10-40 mJ/mm2) and a continuous wave Nd:YAG laser (lambda = 1064 nm, energy density 21-93 W/mm2) were employed in connection with 600-micrometer and 800-micrometer quartz fibers, respectively. In an animal model, effects on the remaining meniscus and the corresponding cartilage surfaces were studied in vivo within an observation period of 6 months. For evaluation of the pathogenesis in laser induced arthrosis, morphological and biomechanical studies were performed on native human menisci. Compared to conventional meniscectomy, laser energy effectively prevents further fibrillation of the meniscal structure. A remodelling of the meniscus did not occur in any experimental group. The degree of reactive synovitis, assessed by macroscopic and histologic scoring, was significantly greater following Nd:YAG laser surgery than after excimer laser resection and conventional surgery (P < 0.05). On X-ray, more progression of degenerative changes was observed following laser procedures than after conventional meniscectomy. The proteoglycan content in the femoral cartilage corresponding to the zone of meniscus resection was significantly lower in the laser group than after conventional meniscectomy (P < 0.01), which substantiates macroscopic and radiographic findings indicating degenerative derangement of the hyaline cartilage. On light microscopy and scanning electron microscopy of meniscus specimens, excimer laser irradiation led to well-delineated resection borders with a mean transitional zone of 20 micrometers, whereas menisci exposed to Nd:YAG laser irradiation presented extensive vaporization zones with the surface covered by an amorphous structure. Menisci irradiated by excimer or Nd:YAG laser energy showed significantly increased rigidity (P < 0.05 and P < 0.01); the maximum value of radial strain at flexion was lower following Nd:YAG laser irradiation (mean 1.5 +/- 0.3%) and following excimer laser irradiation (mean 2.4 +/- 0.3%) than in non-irradiated menisci (mean 3.0 +/- 0.5%). These observations lead to the conclusion that laser-assisted meniscectomy promotes the early manifestation of gonarthrosis by virtue of a reduced femorotibial contact area and alterations in the biomechanical properties of the meniscus.

Animals↗

PubMed1996

[Prognostic significance of surgical morbidity in management of coxal femoral fracture in the elderly patient].

The influence of operative morbidity on clinical long-term results is evaluated in a prospective study employing a consecutive series of 120 patients (mean age, 82.5 +/- 4.7 years) with operatively treated fractures of the coxal femur. Perioperative complications which were observed in 37.5%, with a predominance of urinary tract infection (n = 26), bronchopneumonia (n = 16) and cardiac decompensation (n = 4), were significantly associated with a pertrochanteric fracture localization (p < 0.05), prolonged latency from trauma to surgery (p < 0.01), and a prevalence of three and more internal diseases (p < 0.01). At 1-year follow-up patients with a perioperative complication had a significantly worse performance scoring (p < 0.01) than individuals with an unimpaired perioperative course. This leads to the conclusion that perioperative morbidity decisively influences functional outcome in the elderly patient.

Activities of Daily Living↗

PubMed1995

Optical properties of human articular tissue as implication for a selective laser application in arthroscopic surgery.

BACKGROUND AND OBJECTIVE: Optical density of normal and pathological hyaline cartilage, meniscus, and synovium is determined using native and laser-irradiated tissue samples in order to examine potentials for a selective laser ablation. STUDY DESIGN/MATERIALS AND METHODS: One hundred forty-four autopsy specimens were irradiated in a direct contact mode using a XeCl excimer laser (lambda = 308 nm; 20 ns; 40 Hz; 40 +/- 2.1 J/mm2; 800 microns fused silica fiber) and a continuous-wave Nd:YAG laser (lambda = 1,064 nm; 1 s; 124 +/- 5.4 W/mm2; 600 microns fused silica fiber). Transmission spectra were obtained by microspectrophotometry in a spectral range from 250 to 770 nm. RESULTS: In the ultraviolet spectrum analyzed, optical density (OD) is calculated to 0.81 +/- 0.05 for native hyaline cartilage, to 1.0 +/- 0.07 for meniscal tissue, and to 0.68 +/- 0.04 for synovium. With increasing wavelength the OD steadily decreases reaching mean values of 0.06 +/- 0.01, 0.13 +/- 0.03, and 0.15 +/- 0.04 at 750 nm. Compared to normal tissue degeneration of cartilage and meniscus lead to a significant increase in OD with a maximum relative OD of 4.39 and 1.26, respectively (P < .001 and P < .01). In synovitis the OD increases with a maximum ratio of 1.45:1 (P < .01). Following Nd:YAG laser exposition the OD of the coagulated zone exceeded the value of native tissue by a factor of 9.71 for cartilage, 4.71 for meniscus, and 3.04 for synovium (P < .001). Excimer irradiation leads to a 3.38-fold increase in OD for cartilage, 2.23-fold for meniscal tissue, and 1.6-fold for synovium (P < .01). CONCLUSION: The results presented indicate that a preferential ablation of pathological tissue structures in articular surgery is possible by selecting laser systems with an appropriate spectral emission range. However, thermal laser tissue interaction may lead to severe alterations in optical properties reducing potentials of a preferential or selective laser application.

Adult↗

PubMed1995

[Morphologic, biomechanical and experimental in vivo studies of laser-assisted meniscus resection].

Arthroscopic meniscectomy is associated with an irregularly shaped resection rim leading to further degeneration and a considerable rate of iatrogenic lesions to the adjacent cartilage. In a controlled experimental trial the clinical value of laser-assisted meniscectomy was assessed with special reference to whether laser application can overcome these common shortcomings of conventional surgery. An XeCl excimer laser (lambda = 308 nm, pulsewidth: 20 ns, repetition rate: 10-70 Hz, radiant exposure: 10-50 mJ/mm2) and a continuous wave Nd:YAG laser (lambda = 1064 nm, energy density: 21-93 W/mm2) were used with 600 microns and 800 microns quartz fibers, respectively. The study comprised an analysis of morphological and biomechanical characteristics of the meniscus exposed to laser treatment and an evaluation of reparative and degenerative changes following laser meniscectomy in an animal model. Light microscopy and scanning electron microscopy showed that excimer laser irradiation leads to well delineated resection borders with a transitional zone measuring 20 microns. Specimens exposed to Nd:YAG laser irradiation present extensive vaporization zones with the surface covered by an amorphous structure. Menisci irradiated by excimer or Nd:YAG laser energy show increased stiffness; the maximum value of radial strain at flexion is reduced, with a mean value of 1.5 +/- 0.3% following Nd:YAG laser irradiation and a mean value of 2.4 +/- 0.3% following excimer laser irradiation, compared with 3.0 +/- 0.5% in nonirradiated menisci. In vivo experiments show that laser energy prevents fibrillation of the menisceal structure, which was common in the control group; menisceal regeneration was not observed in any of the experimental groups. The extent of cellular infiltration in the synovial membrane is significantly increased following laser meniscectomy, indicating reactive synovitis (P < 0.05). Radiographs show enhanced progression of degenerative changes following laser surgery compared with conventional menisectomy; measurements of the subchondral bone density in the tibial plateau reveal significantly increased density following Nd:YAG (P < 0.01) and excimer laser irradiation (P < 0.05), confirming these observations. The proteoglycan content in the femoral cartilage corresponding to the zone of meniscus resection is significantly lower in the laser group than in the group subjected to conventional meniscectomy (P < 0.01). These results have various implications for clinical practice.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1995

Laser synovectomy of the knee joint. Experimental results on a new approach to joint surgery.

The clinical impact of laser-assisted synovectomy was investigated in a two-part study consisting of a morphological part with morphometric measurements and an in vivo part using an animal model. A continuous wave Nd:YAG laser (lambda = 1064 nm; power density 18-106 W/mm2; exposure 0.5-5 s) and a XeCl excimer laser (lambda = 308 nm; pulsewidth 20 ns; repetition rate 10-70 Hz; energy density 20-45 mJ/mm2; exposure 10-60 s) were employed in combination with a fused silica fiber with diameters of 600 microns and 800 microns, respectively. In vitro study. Under light microscopy, synovium exposed to Nd:YAG laser energy presents a transitional band (with a mean diameter of 2 mm) with three zones: a carbonized area, a vesicular zone, and a coagulated part. In contrast, pulsed UV-laser irradiation leads only to a narrow transitional zone extending 10-70 microns. Scanning electron microscopy reveals a clear-cut surface following excimer synovectomy, whereas Nd:YAG laser irradiation forms an irregular surface with numerous bursts due to vaporizing activity. In vivo study. Partial synovectomy of the knee joint was performed in two groups of 14 New Zealand white rabbits with a 1064-nm Nd:YAG laser and a 308-nm XeCl excimer laser. Another 14 animals synovectomized in a conventional technique served as a control. Morphological examination and histopathological scoring of the synovial membrane were performed 4 days to 6 months after the operation. The progress of synovial regeneration following excimer laser synovectomy did not differ from observations in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Magnetic resonance imaging (MRI) and arthroscopy in the detection of meniscal degenerations: correlation of arthroscopy and MRI with histology findings.

In a prospective double-blind study, the capability of magnetic resonance imaging (MRI) and arthroscopy in the detection and grading of meniscal degenerations is evaluated by correlating MRI findings and arthroscopic diagnoses with a histologic grading model. In 82.8% of our results, grading based on MRI studies corresponded with the histologic grading classification. In 12 instances a meniscal degeneration verified at light microscopy was not detected at MRI, whereas in 15 cases tomography yielded a false-positive result. The overall accuracy was calculated to be 0.93 with a specificity of 0.79 and a sensitivity of 0.96. Concerning the evaluation of meniscal degenerations, MRI provides a positive predictive value of 0.95 and a negative predictive value of 0.82. Compared with the diagnostic specificity of the anterior and posterior zones, that of the intermediate segment of the meniscus is significantly reduced (p < 0.001). At arthroscopy, meniscal degenerations were diagnosed with an overall accuracy of 38.8%, a sensitivity of 27.5%, and a specificity of 75.5%. In 80 cases of grade 3 abnormalities, five false-negative diagnoses were made initially. These results suggest that MRI offers a valuable diagnostic potential providing reliable information about the internal consistency of the meniscus complementary to diagnostic arthroscopy.

Adult↗

PubMed1992

Acute cholecystitis: a complication in severely injured intensive care patients.

Acute cholecystitis is an often unrecognized and potentially life-threatening complication seen among ICU patients with multiple injury. To investigate the epidemiology of this entity and to evaluate significant etiologic precursors, a prospective clinical and sonographic study was performed in 45 consecutive patients (mean age, 29 years) treated for multiple trauma (mean ISS, 27) in the ICU. Eight of 45 patients developed a cholecystitis during intensive care treatment (18%). Six patients recovered with conservative therapy; in two instances a cholecystectomy was necessary. There was no mortality as a result of cholecystitis. A significant relationship between the severity of the initial trauma (p less than 0.05), the number of blood transfusions (p less than 0.01), and the incidence of acute cholecystitis was found. Other factors such as prolonged shock, respiratory failure, or parenteral alimentation were less prevalent and were not temporally related to the onset of the disease. All patients had large amounts of narcotics administered over a prolonged period, so that narcotic-induced biliary stasis appeared to be another eminent factor involved in the genesis of posttraumatic cholecystitis. Our results lead to the conclusion that acute cholecystitis occurs with an unexpectedly high incidence and that a high remission rate can be expected following conservative treatment provided that appropriate serial ultrasound examinations are performed.

Acute Disease↗

PubMed1992

[Biomechanical aspects of the over-the-top reconstruction of the anterior cruciate ligament].

Strain characteristics of anterior cruciate ligament grafts inserted in the over-the-top technique were studied in an in-vitro model. A cruciate ligament attached at the center of the anatomical insertion sites provides a constant preload and accomplishes the principle of isometry during the whole range of motion. In contrast, the over-the-top reconstructed ligament shows an increasing laxity proportional to the degree of joint flexion due to an approach of the attachment areas. These observations indicate that a sufficient ligament function is not provided so that the over-the-top reconstruction cannot be recommended as method of choice.

Anterior Cruciate Ligament↗

PubMed1991

[Clinical results of Palmer's primary cruciate ligament insertion without augmentation].

The clinical importance of primary cruciate ligament reconstruction without augmentation-plasty is discussed on the background of long term results following 51 operations. Based on standardized methods of evaluation 38 patients had a very good and good result, in eleven cases the operation lead to a fair and in two cases to a poor result. A significant instability with a pivot shift grade III was recorded in two cases: twelve patients showed a low degree of instability whereas 37 patients had regained full stability. The coincidence of a cruciate ligament lesion and a rupture of a collateral ligament had a negative influence on the postoperative long term result (p less than 0.01). Our results suggest that a primary repair without augmentation-plasty is a qualified procedure for stabilizing the knee joint in cases with an acute femoral rupture without accompanying collateral lesions. In patients with old ruptures or a complex joint lesion primary repair with augmentation is recommended.

Evaluation Studies as Topic↗

PubMed1991

[Ender nailing for stabilization of pertrochanteric fractures in advanced age. A safe procedure?].

The postoperative course of 138 patients with a pertrochanteric fracture treated by nailing according to Ender is analysed with regard to the operative morbidity and lethality. As secondary factors associated with morbidity the specific and unspecific rate of complications, the lethality, the perioperative loss of blood and the duration of postoperative hospitalisation are evaluated. Specific complications occurred in 27%, unspecific complications in 50%, and the rate of hospital mortality was 15.2%, 60.9% of patients required a postoperative transfusion to compensate the perioperative blood loss. In contrast to other authors we cannot regard Ender nail osteosynthesis as a lowrisk procedure with a low operative morbidity. When choosing the treatment procedure alternative methods of stabilisation should be taken into account. An intensive postoperative care is of utmost importance in elderly patients.

Aged↗

PubMed1991

[Management of femoral neck fracture with an intermediate (dual head) prosthesis in geriatric surgery].

Between 1980 and 1989 in 195 elderly patients with fractures of the femoral neck a duo-cup endoprosthesis was inserted. The average age was 78 years, most of them were high risk patients with sometimes more than 2 preexisting diseases. The hospital mortality after hip replacement was 9.7%, specific complications like protrusio acetabuli and shaft fractures were not observed. In 2 cases immediate postoperative luxation required reintervention. The incidence of infection was significantly reduced to 2.4% after antibiotic therapy. When discharged from hospital, 86% had a good functional result. We regard hemiarthroplasty with duo-cup endoprosthesis as an acceptable alternative to total hip replacement in elderly patients with fractures of the femoral neck.

Aged↗

PubMed1991

The clinical value of magnetic resonance imaging in the evaluation of meniscal disorders.

This prospective double-blind study was designed to evaluate the capability of magnetic resonance imaging to serve as a diagnostic tool in patients who have a clinically suspected disorder of the meniscus. The imaging studies provided a diagnostic accuracy of 72 per cent, a sensitivity of 88 per cent, and a specificity of 57 per cent. The positive and negative predictive values were 66 and 83 per cent. The diagnostic sensitivity was 94 per cent for lesions of the medial meniscus; this value differed significantly from that of 78 per cent for lesions of the lateral meniscus (p less than 0.05). The 37 per cent specificity for lesions of the medial meniscus was extremely low compared with the rate of 69 per cent for lesions of the lateral meniscus (p less than 0.01). In the intermediate part of the meniscus, the diagnostic sensitivity was 37 per cent on the medial side and 23 per cent on the lateral side; these values were significantly less than the average of 74 per cent for the other meniscal segments (p less than 0.001). The imaging studies provided an over-all accuracy of 67 per cent in the detection of degeneration of the meniscus, 78 per cent in the identification of meniscal tears, and 82 per cent in the delineation of postoperative lesions.

Adolescent↗