Biomedical subjects

Lothar Kinzl

Publications and source records attributed to Lothar Kinzl.

35 records · Page 2Linked to original sources

PubMed2004

Computer-guidance in percutaneous screw stabilization of the iliosacral joint.

Nine patients with instability and one patient with degeneration of the iliosacral joint were treated surgically. The posterior pelvic ring was stabilized with the assistance of an optoelectronic navigation system. Registration was ensured by using fiducial screws in the iliac crest or by collecting landmarks on the external fixator. Computed tomography scans taken postoperatively provided additional information regarding implant localization in all patients. Accurate placement of 21 of 22 implanted iliosacral screws was observed. Two of the 21 screws touched the wall of the second sacral foramen without perforating the canal. One screw perforated the anterior wall of the sacrum because the navigated guide wire was bent during implantation. The initial results indicate that computer-aided frameless navigation in surgery of the iliosacral joint can facilitate surgical performance during screw stabilization in selected patients. Two important issues must be considered in the clinical application of this technique: first, any relative migration of the iliac and sacral bone structures between computed tomography scans taken preoperatively and intraoperative navigation may result in an intolerable inaccuracy of computer guidance. Second, bending of the guide wire of the tracked power drive, which cannot be accommodated by the navigation system, will lead to misguidance; therefore, only navigated drill sleeves should be used.

Bone Screws↗

PubMed2004

Blunt chest trauma induces delayed splenic immunosuppression.

Severe blunt chest trauma is frequently associated with multiple organ failure and sepsis. Posttraumatic immunosuppression seems to play a major role in their development. However, the immunologic alterations following pulmonary contusion are insufficiently elucidated. Specifically, it remains unknown whether immunocompetent cells located distant from the site of the impact are affected. We therefore aimed to characterize the influence of pulmonary contusion on lymphocytes and splenic macrophages. Male C3H/HeN mice (n = 8-10/group) were anesthetized and subjected to trauma or sham procedure. Blunt chest trauma was induced by a blast wave focused on the thorax. Two or 24 h later, splenocytes and splenic macrophages were isolated and stimulated for 48 h. The cytokine release (IFN-gamma, IL-2, IL-3, IL-10, IL-12, IL-18) from splenocytes as well as from splenic macrophages (TNF-alpha, IL-10, IL-12, IL-18) and plasma levels of TNF-alpha and IL-6 were quantified by ELISA. The results indicate that at 2 h after blunt chest trauma, plasma TNF-alpha and IL-6 were markedly increased. At the same time, no differences in splenocyte cytokine production were detectable. However, at 24 h a significantly depressed cytokine release was observed in trauma animals. Furthermore, splenic macrophages showed a significantly decreased production of TNF-alpha, IL-10, and IL-12 at 24 h and markedly increased release of IL-18 at 2 h after trauma. These results indicate that blunt chest trauma causes severe immunodysfunction of lymphocytes and splenic macrophages. Thus, lung contusion as a localized type of trauma causes dysfunction of immunocompetent cell populations, which are located distant from the site of injury.

Animals↗

PubMed2003

Buruli ulcer: a systemic disease.

We studied a 4-year-old boy from Angola who presented with 2 cutaneous ulcerations of the right hip and osteomyelitis of the left knee and right ankle. Mycobacterium ulcerans disease was confirmed by direct smear examination and by polymerase chain reaction. The patient was treated with antimycobacterial drugs, repeated surgical debridement, skin grafting, and daily hyperbaric oxygenation. Despite significant improvement of the local lesions in response to hyperbaric oxygenation, swelling of the right knee, without associated skin lesions, was noted. Radiological evaluation and open biopsy revealed extensive metaphyseal osteomyelitis of the right distal femur. A 99technetium bone scan revealed an additional focus in the diaphysis of the left humerus, without soft-tissue involvement. This case documents, for the first time (to our knowledge), the systemic spread of M. ulcerans, with subsequent multifocal osteomyelitis and secondary involvement of soft tissues and supports the hypothesis that low tissue oxygen levels promote hematogenous spread of M. ulcerans. Sickle cell anemia, with associated microthrombosis and microinfarction, may have contributed to tissue hypoxia.

Antitubercular Agents↗

PubMed2003

Minimally invasive ventral spondylodesis for thoracolumbar fracture treatment: surgical technique and first clinical outcome.

A new instrumentation system for ventral stabilization of the spine that can be used for an endoscopic and minimally invasive approach was developed. We describe the implantation technique and report on the first clinical results. This prospective study covers the first 45 patients to undergo this new technique since it was introduced in 1999. In all patients the operation was successfully performed in a completely minimally invasive procedure. Mono- and bisegmental stabilization was performed mainly at the thoracolumbar junction after initial posterior instrumentation in most cases. Lesions varied from fresh/old fractures to metastases (T5-L3). Pre- and postoperative follow-up included clinical examination and radiological visualization via X-ray and computed tomographic scan. Our experience with this minimally invasive procedure demonstrated the feasibility of the method.

Adolescent↗

PubMed2003

Biochemical characterization of individual injury pattern and injury severity.

BACKGROUND: Estimation of trauma severity currently relies on clinical diagnoses and scoring systems. However, the early estimation of the severity of chest trauma and overall soft tissue trauma (STT) remains insufficient. Traditional trauma scoring systems fail to reflect the individual trauma pattern and severity, neglecting the different outcomes after injuries in different body regions. Therefore, the aim of this prospective study was to detect laboratory markers that may reflect the pattern and extent of individual trauma in the very early phase after injury. PATIENTS AND METHODS: In 107 non-selected trauma patients, blood samples were collected almost immediately and then at short intervals after the trauma. In addition to the biochemical analysis of 20 different mediators viewed as potential trauma markers, the following data were correlated with the laboratory results: injury severity score (ISS), polytrauma score (PTS), Ulmer score HTAPE (trauma pattern specific: head (H), thorax (T), abdomen (A), pelvis (P), extremities (E); 0-3 degrees each), multiple organ failure score (MOF), overall, primary and secondary lethality. RESULTS: ISS and the severity of head injury were clearly higher in non-survivors (n=17) than in survivors (n=90) (median ISS: 35 versus 18; median severity of head injury (H): 3 versus 1). Whereas head injury was correlated with early death ( 3 days post-trauma) was influenced by thoracic trauma (r=0.15) as well as by soft tissue trauma (STT, r=0.12). Of all investigated mediators, interleukin-6 (IL-6) displayed the highest correlations (r=0.66, P<0.00001) with the extent of chest trauma, followed by correlations with PTS, STT, fracture trauma (FT) and ISS during the first hour after trauma. There was no correlation between IL-6 and head injury. The extent of STT was correlated best to IL-8 (r=0.75), IL-6 (r=0.54), and creatine kinase (CK, r=0.49) plasma concentrations. CONCLUSION: In the very early stage after an accident the severity of chest trauma is strongly correlated with the plasma concentration of IL-6, and the extent of overall soft tissue trauma (STT) to plasma concentrations of IL-8, IL-6, and CK.

Adolescent↗

PubMed2003

Axial compression force measurement acting across the strut graft in thoracolumbar instrumentation testing.

OBJECTIVE: Current recommendations for spinal implant testing do not consider the determination of axial compression forces of the overbridging implant on the strut graft. No direct data exist on the influence of load transfer through the strut graft and of the kind of instrumentation, especially in thoracolumbar corpectomy models. DESIGN: Therefore in this biomechanical in vitro study a method for measurement of the axial compression force acting across the strut graft in different thoracolumbar instrumentations was developed. METHODS: In this in vitro study, a corpectomy model was simulated and anterior, posterior and combined short fixation devices currently available were tested under pure moments to evaluate their biomechanical stabilizing characteristics. Range of motion, neutral zone and the axial compressive force acting on the strut graft were measured continuously in the three primary directions. RESULTS: Without loads, the combined stabilization and followed by anterior instrumentation created a higher axial compression force than the dorsal instrumentation on the strut graft. Especially during maximal extension there was no axial compression of the dorsal instrumentation on the strut graft, which resulted in an increase of the range of motion. CONCLUSION: The feasibility of the new method was demonstrated in this study. For the purpose of standardization and comparison it should be considered in spinal implant testing.

Aged↗

PubMed2003

Influence of preoperative mechanical bone quality and bone mineral density on aseptic loosening of total hip arthroplasty after seven years.

OBJECTIVE: To test mechanical bone quality and bone mineral density of the femoral head at the day of implantation as indicators for femoral prosthesis loosening. METHODS: Mechanical bone quality of a femoral head slice was assessed by destructive compression testing combined with bone mineral density measurements using peripheral quantitative computed tomography. Fourteen patients with walking pains were attainable for a radiographical follow-up mean 7.1 years after implantation. RESULTS: Radiolucent lines along the stem were evident in 11 of 14 femurs, most of them seen in Gruen zones 7, 6, 1, 3, 14, and showed strong correlations to preoperative bone strength (r=-0.80; P<0.001) and axial stiffness (r=-0.75; P=0.002), yet not to bone mineral density (r=-0.67; P=0.009). Slight varus deviations <3 degrees were noted in six femurs. Preoperative strength was reduced in this femurs to 54% (P=0.006), and stiffness to 61% (P=0.038), while bone mineral density did not differ significantly. CONCLUSIONS: Femoral prosthesis loosening after seven years can be predicted by mechanical bone quality of the femoral head at the time of implantation. Bone mineral density measurements may also indicate future stem loosening but have to interpreted carefully, keeping in mind a poorer predictive value. RELEVANCE: Indications and choice of type of hip arthroplasty should be balanced in osteoporotic bones in particular. While preoperative bone mineral density measurement allows the prediction of mechanical bone quality, its relevance in predicting failure in arthroplasty treatment remains unclear.

Aged↗

PubMed2003

The pattern of preformed cytokines in tissues frequently affected by blunt trauma.

The aim of this prospective study was to determine the local concentrations of inflammatory mediators in various tissue types frequently affected by trauma to estimate the role of prestored cytokine release by mechanical tissue trauma in the induction of a systemic inflammatory response syndrome. The degree of tissue damage, evaluated by its systemic release of inflammatory mediators, represents an important factor concerning the outcome of trauma patients. Clinical trials indicate that the kind of traumatized tissue influences the cytokine pattern measured in patients blood afterwards. However, the tissue-specific mediator composition underlying this systemic mediator release is rarely elucidated. Upon approval of the local IRB/EC, skin, subcutaneous fat, muscle, cancellous bone, and lung tissue were obtained during standard surgical procedures. The protein-based concentrations of Interleukin (IL)-6, IL-8, IL-10, and IL-12 were determined in tissue homogenates by enzyme-linked immunoabsorbant assay (ELISA; n = 60 samples). Albumin was measured to evaluate the degree of blood contamination of tissue samples. IL-6 and IL-8 were consistently detectable in more than 95% of the tissue specimens. Lung and cancellous bone presented by far the highest concentrations of these cytokines, whereas skin, subcutaneous fat, and muscle showed significantly lower levels. IL-10 was not detectable in 88%; IL-12 could not be measured in 63% of the samples. Cytokine concentrations did not correlate with the amount of albumin measured in tissue specimens. Due to their consistent presence at the tissue level, high systemic concentrations of IL-6 and IL-8 in patients blood, seen after pulmonary trauma, long bone fractures, or soft tissue injury, may be interpreted as an overspill of local trauma mediators. This indicates their relevance in post-traumatic monitoring. Furthermore, albumin is a suitable and necessary indicator to evaluate influences of possible blood contamination in tissue samples.

Adipose Tissue↗

PubMed2003

Cardiopulmonary, histological, and inflammatory alterations after lung contusion in a novel mouse model of blunt chest trauma.

Severe blunt chest trauma remains an important injury with high morbidity and mortality. However, the associated immunological alterations are poorly understood. Existing big animal models require large-scale settings, are often too expensive, and research products for immunological studies are limited. In this study we aimed to establish a new model of blunt, isolated and bilateral chest trauma in mice and to characterize its effects on physiological and inflammatory variables. Male C3H/HeN mice (n = 9-10/group) were anesthetized and a femoral artery was catheterized. The animals were subjected to trauma or sham procedure and monitored for 180 min. Blunt chest trauma was induced by a blast wave focused on the thorax. Trauma intensity was optimized by varying the exposure distance. Blood pressure, heart rate, respiratory rate, arterial blood gases and plasma cytokine levels were measured. Macroscopic and microscopic examinations were performed. In addition, outcome was evaluated in a 10-day survival study. Chest trauma caused a drop (P < 0.05) in blood pressure and heart rate, which partly recovered. Blood gases revealed hypoxemia and hypercarbia (P < 0.05) 180 min after trauma. There was marked damage to the lungs but none to abdominal organs. Histologically, the characteristic signs of a bilateral lung contusion with alveolar and intrabronchial hemorrhage were found. Plasma interleukin-6 and tumor necrosis factor alpha were considerably increased after 180 min. Blunt chest trauma resulted in an early mortality of 10% without subsequent death. On the basis of these findings, this novel mouse model of blunt chest trauma appears suitable for detailed studies on immunological effects of lung contusion.

Animals↗

PubMed2003

Induction of apoptosis following blunt chest trauma.

The cause for the high morbidity of blunt chest trauma is not fully understood. It is still unclear if and to what extent a second insult, e.g., apoptotic tissue damage initiated by the primary insult itself, may contribute to the development of serious complications. This study was done to elucidate whether a pulmonary contusion may induce programmed cell death. Sixty-four Wistar rats were evenly randomized to eight experimental groups: four sets were subjected to a standardized blast wave injury and sacrificed 6, 24, 48, and 72 h after the trauma; four groups served as controls for the same time points. Lung and liver samples were stained (H & E; TUNEL), and PMN infiltration was determined by myeloperoxidase (MPO) activity. Caspase 8 was analyzed by Western blot, and TNF-alpha plasma levels by ELISA. Postmortem examination revealed bilateral pulmonary contusion in trauma animals with higher (P < 0.05) numbers of apoptotic cells in lung but not in liver tissue as early as 6 h after the injury. This amount gradually increased and reached a maximum after 48 h: 6.8 +/- 1.1 apoptotic cells/hpf vs. 0.6 +/- 0.06 in controls. Chest trauma caused an increased expression of active caspase 8 in lung but not in liver tissue at 48 and 72 h. TNF-alpha plasma levels were not different. MPO activity in lung tissue of trauma animals increased (P < 0.05) after 6 h and peaked at 72 h. This study has provided the first evidence that apoptotic cell death in lung tissue is initiated following (experimental) pulmonary contusion. The exact mechanism remains, however, unclear and has to be elucidated further.

Animals↗

PubMed2003

Enhanced primary stability through additional cementable cannulated rescue screw for anterior thoracolumbar plate application.

OBJECT: The authors conducted a study to investigate the biomechanical in vitro influence of a new anchorage system for fixation of anterior stabilization devices and the possibility of using additional cement after screw insertion to compensate for poor bone quality. The incidence of osteoporosis-related fractures has increased nearly twofold in the last decade. Because of problems associated with anterior screw fixation such as loosening, mechanical failure, and the weakness of osteoporotic bone, current surgical treatments of vertebral body (VB) fractures are problematic. This is due to poor fixation strength of anterior screws in the adjacent segments. The aim of this study was to determine whether a new cemented and uncemented VB screw provides improved primary stability following placement of anterior instrumentation in cases of fracture. METHODS: The primary stability-related parameters of a new uncemented/cemented screw were compared with those of conventional monocortical screw fixation in a burst fracture model in which strut graft and anterior overbridging instrumentation were used. The use of the new uncemented screw improved the range of motion (ROM) of the stabilized spine in flexion-extension by approximately 22%, in rotation by 20%, and in lateral bending by 15%. Additional cementation improved the ROM by approximately 41% in flexion-extension, 32% in rotation, and 30% in lateral bending compared with conventional monocortical screw fixation. CONCLUSIONS: The new cannulated screw improves fixation strength and primary stability parameters. It is useful in the initial treatment of fractures in cases of poor bone quality and as a rescue device if previously inserted screws do not remain securely in place.

Biomechanical Phenomena↗

PubMed2002

The traumatic spondylolisthesis of the axis. A biomechanical in vitro evaluation of an instability model and clinical relevant constructs for stabilization.

OBJECTIVE: Stepwise destabilization of the traumatic spondylolisthesis C2 with an increasing anterior defect of C2-C3 was investigated. The three-dimensional stabilizing capabilities of posterior transpedicle screw osteosynthesis and two anterior plate systems C2-C3, the H-plate and the titanium locking plate were tested. DESIGN: A biomechanical in vitro study was performed using a standardized experimental protocol in a spine tester. BACKGROUND: The extent of the instability of the traumatic spondylolisthesis of C2 within its different types remains unclear. Posterior and anterior approaches for stabilization exist for patients with isthmusfractures at C2, the stabilizing effect has not been demonstrated yet. METHODS: The motion levels from C2-C3 in six human specimen were tested in flexion, extension, right and left lateral bending and left and right axial rotation. The specimens were tested intact, after destabilization and after stabilization. RESULTS: In extension and axial rotation, each step of destabilization decreased the moment significantly, to achieve the range of motion of the intact specimen. In flexion a statistical significant destabilization after separation of the posterior longitudinal ligament was present. The flexibility tests showed an increasing range of motion of the posterior transpedicle screws, with increasing anterior instability markedly in flexion and extension. After H-plate and locking plate fixation, a significant decrease of the range of motion resulted in flexion. The stiffness in flexion and extension increased consecutively, while in lateral bending and axial rotation the transpedicle screw fixation showed the highest stiffness. CONCLUSIONS/RELEVANCE: The traumatic spondylolisthesis of C2 is a significantly unstable injury in case of additional segmental damage of C2-C3. Anterior stabilization in these injuries is mandatory.

Aged↗

PubMed2002

Effects of one-plane and two-plane external fixation on sheep osteotomy healing and complications.

OBJECTIVES: Comparison of one-plane and two-plane external fixation in terms of successful healing, incidence of complications, and biomechanical stability in a sheep model. BACKGROUND: Rigid fixation is preferred in open and comminuted fractures with a reduced blood supply, preventing infection and healing delay, but more often a flexible device is recommended even in unfavourable healing conditions. METHODS: The left tibiae of fifteen sheep were osteotomized and laterally fixed with a four-screw unilateral fixator frame (axial stiffness 183 N/mm) to a 3 mm gap size. In 9 of 15 sheep, an additional four-screw unilateral external fixator was anterolaterally attached (total axial stiffness of both frames 388 N/mm). After sacrificing, quality of osteotomy healing was assessed by mechanical and radiological evaluations. Osteogenesis was measured using fluorescence microscopy. RESULTS: Two distal fractures through the pin-tracks, three non-unions and four deep infections occurred after two-plane fixation. These failures excluded, osteotomy healing showed inferior results after two-plane fixation with reduced callus formation, bone mineral content, and bending stiffness amounts, respectively. Osteogenesis was halved following two-plane fixation in the remaining sheep. CONCLUSIONS: Two-plane fixation was not sufficient to reach successful osteotomy healing in our study. While higher rigidity was expected to prevent complications, healing in this group might have been disturbed by a reduced blood supply. The optimal stabilisation for a given fracture depends on many factors, including the biomechanical and biological environment. RELEVANCE: Considering our results and the literature discussed in this manuscript, good bone healing with minor risks of infections can be achieved using an unilateral one-plane fixator with only four screws, and its application on a muscle free position like the medial and anterior site of the sheep tibia.

Animals↗

PubMed2002

Spinal navigation in tumor surgery of the thoracic spine: first clinical results.

In this clinical study, the accuracy of computed tomography-based and computer-guided decompression and insertion of pedicle screws in patients who have had tumor-related posterior surgery of the thoracic spine was evaluated. Eight patients with advanced metastatic disease were treated surgically using a posterior approach with the assistance of an optoelectronic navigation system. Postoperative computed tomography scans were obtained for all patients and provided information regarding decompression and transpedicle implant localization. In all eight patients accurate decompression of the spinal canal was seen. Using the navigation system, 22 of 26 scheduled transpedicle screws were inserted using computer guidance. Eighty-six percent (19 of 22) of the navigated pedicle screws were positioned centrally in the bone. Initial results indicate that computer-aided frameless navigation in tumor surgery of the thoracic spine is a safe system to improve surgical performance during posterior decompression and transpedicle stabilization. Although computed tomography-based computer-assisted spinal navigation is important, the system is not 100% accurate. Therefore, application of the navigation system should be restricted to experienced surgeons who can continue the operation using a conventional approach. Finally, detailed knowledge of the principles of the tracking systems is necessary to prevent possible misinterpretation of information provided by the computer.

Bone Screws↗

PubMed2002

Chemokine activation within 24 hours after blunt accident trauma.

Chemokines mediate the migration of leukocytes to sites of inflammation. Changes in the plasma concentration of interleukin (IL)-8 and macrophage inflammatory protein (MIP)-1beta have not been investigated in the very early phase starting immediately after unintentional trauma. Enrolled in the study were 94 patients with multiple blunt injuries. Blood samples were collected at the scene of accident, then at regular intervals for 24 h. IL-8 and MIP-1beta plasma levels were determined by commercial test kits. Patients were grouped according to trauma severity, pattern of injury, as well as survivors vs. nonsurvivors. Serious casualties [Injury Severity Score (ISS) > or = 32] revealed a significant increase in IL-8 compared to only a slight elevation in individuals with an ISS < 32. Nonsurvivors showed a highly significant (P < 0.005) increase in IL-8 levels beginning immediately after admission. Trauma resulted in a modest activation of MIP-1beta production without differences regarding trauma severity, pattern of injury, or survival. A very strong trauma stimulus is necessary to activate IL-8 production. In contrast to MIP-1beta, IL-8 levels were significantly elevated in nonsurvivors compared to survivors. Therefore, IL-8 might be an early predictor of survival.

Accidents↗

PubMed2002

Ultrasound, a new tool for surface matching in computer-navigated surgery.

OBJECTIVE: The object of this study was to investigate the feasibility of generating a bone surface from data provided by an ultrasound examination and to match this surface with the previous computed tomography (CT) scan. METHODS: From a CT data set of a training model of the pelvis, a three-dimensional surface was extracted by global thresholding-based segmentation. The same model was placed in a water basin, and ultrasound images were taken with a guided ultrasound transducer. The three-dimensional surface was generated from the ultrasound data set, and the two surfaces were matched in a semiautomatic mode. RESULTS: With special segmentation methods, a surface could be extracted automatically from the CT and the ultrasound data set. From these segmented ultrasound slices, a volume data set of the model was generated. After approximate initial matching, the local matching process was completed automatically. CONCLUSION: One of the limitations in computer-assisted surgery is the complicated matching process. Using special algorithms, a surface was extracted from the data set of an ultrasound examination and matched in a semiautomatic mode with the surface of a CT data set, facilitating the matching process.

Algorithms↗

PubMedDate not supplied

The effectiveness of physiotherapy after operative treatment of supracondylar humeral fractures in children.

The indications for physiotherapy after supracondylar humeral fractures in children are not clear in the literature, even in the presence of an active or passive limitation of elbow joint motion. The authors therefore performed a prospective randomized study to assess the effectiveness of physiotherapy in improving the elbow range of motion after such fractures. The authors studied two groups of 21 and 22 children with supracondylar humeral fractures Felsenreich types II and III, all without associated neurovascular deficits. All children were treated by open reduction and internal fixation with Kirschner wires inserted from the radial side of the humerus. Postoperative follow-up at 12 and 18 weeks showed a significantly better elbow range of motion in the group with weekly physiotherapy, but there was no difference in elbow motion after 1 year. In each group, one child had an extension deficit of 15 or 20 degrees. The authors conclude that postoperative physiotherapy is unnecessary in children with supracondylar humeral fractures without associated neurovascular injuries.

Child↗