Biomedical subjects
Publications and source records attributed to A Gänsslen.
An unusual case of an anterior column fracture of the acetabulum with extended marginal impaction at the posterior column is presented. Fracture fixation was primarily performed by an ilioinguinal approach followed by a posterior approach with surgical dislocation of the hip to reduce the impacted fragments.
Percutaneous sacroiliac screw fixation is technically demanding and can result in complications mainly related to imaging problems. Furthermore, the conventional technique performed using fluoroscopic control is associated with a long radiation exposure. The purpose of this study was to evaluate the accuracy of two navigation technologies used in traumatology; fluoroscopy and Iso-C3D navigation. A total of 40 screws were placed (20 with Iso-C3D, 20 with 2D fluoroscopy) at levels S1 and S2. With both technologies, all S1 screws could be placed correctly, but four (10%) incorrect placements were seen at S2 with fluoroscopy navigation. With all Iso-C3D navigated drillings, no perforation was seen. Iso-C3D navigation therefore proved superior to 2D fluoroscopy navigation for sacroiliac screw fixation in an experimental set-up designed to assess accuracy.
For pelvic fractures, pre- and postoperative imaging includes spiral computed tomography, providing high resolution and accuracy. In conventional pelvic operations, these image data cannot be used directly. Intraoperative imaging is limited with fluoroscopy and visualization by the approaches. One solution in terms of precision and reduction of radiation exposure could be computer-assisted surgery (CAS). This method can be divided into navigation, which requires active registration, CT based navigation and registration-free fluoroscopy-based or Iso-C-3D-based navigation. Applications for CAS in the pelvis include sacroiliac screw osteosynthesis in pelvic ring fractures, navigated periacetabular screw fixation, and correction operations for malhealed pelvic ring fractures. Nowadays, CAS is still costly and frequently requires additional staff. However, it helps to reduce complications caused by implant placement. With the introduction of new health care requirements in Germany, this may be an economic argument as well. Current developments focusing on accurate navigated reduction will provide new indications for CAS, further decrease complication rates, and help to reduce the invasiveness of pelvis operations.
Open reduction and internal fixation is the treatment of choice for displaced acetabular fractures. The surgical approach depends on the fracture type, concomitant injuries, and general condition of the patient. The ilioinguinal approach provides a good exposure to the medial wall and is associated with an acceptable degree of surgical trauma. Exposure of the joint surface, however, is difficult when using the ilioinguinal approach. We report a case of a polytraumatized 39-year-old patient who sustained a posterior hip displacement and a two-column acetabular fracture. An osteotomy of the iliac ala was performed via an ilioinguinal approach to fragments of the acetabular surface that were displaced distally. Thereby, reposition of a craniolateral fragment was achieved without the need to extend the surgical approach or to perform a second incision.
Anatomical reconstruction and stable internal fixation is the treatment of choice in displaced acetabular fractures. Marginal impaction zones are of negative prognostic value. They are normally treated with a cancellous bone graft from the greater trochanter. In the presented case, a secondarily failed acetabular reconstruction with redisplacement of the acetabular dome was treated with several corticocancellous blocks filled in the dome defect. In this case, a comminuted area and secondary displacement could be successfully treated with anatomical reconstruction. This resulted in joint congruency and an acceptable long-term result after 16 years.
The application of the pelvic clamp as a tool for emergency stabilization of unstable pelvic ring fractures has proved to be a life-saving procedure. Using correct technique, the pelvic clamp can be applied within a few minutes after the patient's admission. To avoid severe complications (eg, pin perforation into the pelvis) during the application, anatomic landmarks for the correct pin placement have to be defined. The surface landmarks that are presently recommended for the correct pin placement are not always reliably found due to deformation of the body surface caused by swelling and hematoma. Our experience with 43 emergency applications of the pelvic C-clamp showed that reliable anatomic landmarks on the bony surface of the innominate bone could be identified to ensure correct pin placement. The ideal insertion point of the pins is an anatomic region on the lateral cortex of the ileum, where an easily palpable "groove" is formed by angulations of the lateral cortex of the iliac wing. Being increasingly used as an entry point for percutaneous transiliosacral screw fixations of sacroiliac joint injuries and sacral fractures, this region, which is close to the sacroiliac joint, represents an ideal point for maximum compression of the posterior pelvic ring. With the described technique, this "groove" can be identified easily even in emergency situations by blunt palpation with an instrument, avoiding the time-consuming use of a fluoroscope in most cases.
Up to now navigated reduction control based on computed tomography (CT) image data could not be used commercially. With newly developed software, a transverse fracture of the acetabulum was reduced with navigation control in a laboratory test. The results were compared to visual and tactile control in a foam pelvis and specimen. Measurements were done with another magnet-based navigation system. The residual dislocation was measured with translation (mm) and rotation (degrees). Compared with visually controlled reduction, navigated reduction led to a residual dislocation of 0.7 mm and 0.9 degrees. Navigated reduction based on CT image data is also accurate for reduction of joint fractures under laboratory conditions. Further improvements of the software are planned for later in vivo use.
After having been introduced in the seventies computed tomography (CT) has become an important instrument for the diagnosis of difficult joint fractures. With the evolution of the Spiral-CT with multiplanar reformations and three-dimensional (3D-) reconstructions the quality of visualization has been improved considerably. In comparison with conventional radiography the actual CT scanners give a clear image of the fracture configuration and the degree of fragment displacement in joint fractures. Additional information about sub-/luxations of the joint, impaction and comminution is also clearly visualized by the CT. This means a rise in quality of fracture classification and enables a detailed view of the fracture pattern. These findings provide the basis for gratifying treatment regimens and surgical management of the injured joint. By the use of innovative reconstruction methods the CT allows exact visualization of internal fixations/osteosynthesis and secondary angular/rotation or length deformities postoperatively. Furthermore, reconstructed 3D-views enable preoperative computer simulated plannings of internal fixations and of reduction control intraoperatively. In fact, the actual Spiral-CT scanners are nearly equivalent in costs and total radiation dose compared to the performance of special projections of conventional radiographs. Thus, we recommend to enlarge the performance of additional CT diagnostic in difficult joint fractures and special pre- or postoperative cases.
Sacral fractures are frequently misdiagnosed or overlooked, as the majority of the patients are suffering from polytrauma situations. Obvious clinical signs both of the fracture and the associated neurological complications are missing. A poor longterm outcome with pain and urogenital disorders is frequent. Based on clinical and biomechanical studies a new concept for internal fixation of transsacral pelvic instabilities combined with decompression of the central canal is applied. To approach the sacrum, a posterior longitudinal incision is carried out and can be modified according to the fracture pattern. Decompression and anatomic reduction is performed and the fracture stabilized with minimized small fragment implants which are solely fixed in the sacrum. 32 patients were treated according to this protocol between 1989 and 1996. Bony healing occurred in all but one case. A complete anatomical sacral reconstruction was achieved in 80 % of the cases, another 16 % had close to anatomic (< 5 mm) reconstruction. In eight cases a primary neurologic deficit was present, with five complete or partial recoveries directly postoperative. Complications occurred in seven patients with two secondary displacements.
A newly developed software module for computer-assisted surgery based on a commercially available navigation system allows simultaneous, independent registration of two fragments and real-time navigation of both fragments while reduction occurs. To evaluate the accuracy three fracture models were used: geometric foam blocks, a pelvic ring injury with disruption of the symphysis and the sacroiliac joint, and a pelvic ring fracture with symphysis disruption and a transforaminal sacral fracture. One examiner did visual and navigated reduction and in all experiments the end point was defined as anatomic reduction. Residual displacement was measured with a magnetic motion tracking device. The results revealed a significantly increased residual displacement with navigated reduction compared with visual control. The differences were low, averaging 1 mm for residual translation and 0.7 degrees for the residual rotation, respectively. Residual displacement was small in both set-ups and may not be clinically relevant. Additional development of the software prototype with integration of surface registration may lead to improved handling and facilitated multifragment tracking. Use in the clinical setting should be possible within a short time.
Anatomic reduction of displaced fractures is limited by the chosen surgical approach and intraoperative visualization. Preoperative Computed Tomography (CT) enhances the analysis of the fracture pattern and provides accurate spatial relationships. Computer Assisted Surgery (CAS) was introduced to increase the accuracy of specific surgical procedures. CAS systems can be used for implant placement or osteotomies in intact bone or reduced situations prior to obtaining the CT data, as differentiation into different datasets related to specific fragments is not yet possible. We present a model that allows "virtual" controlled reduction, providing computer assistance during the fracture reduction. Prior to clinical application, the accuracy of the process of virtual reduction must be proven in an experimental setting. An in vitro fracture model with two body fragments and a motion tracking system for three-dimensional (3D) control (accuracy 0.1 mm and 0.1 degrees ) was used. Two methods were employed: direct visualization and reduction by the examiner, and "virtual" reduction, performed solely with the use of a computer image, in which the examiner lacks any direct visualization of the fragments. The results of this very simplified "fracture" model indicate that the overall difference between direct and virtual controlled reduction was very small. A significant difference of 0.3 mm (0-1.8 mm) was seen for the residual displacement represented by the Euclidean distance (p < 0.01), whereas the difference in the residual angulation was not significant (p > 0.05). The methods tested revealed that virtual controlled reduction is nearly as accurate as direct visualization. Reduction control utilizing a motion tracker system reveals accurate 3D information in this simplified reduction setup, and is now used as a standard setup for analyzing realistic fracture models.
Between 1985 and 1995, 9380 traffic accidents occurring in the area of Hannover, Germany, were analysed; 12428 individuals had been injured and 387 (3.1%) had sustained a pelvic-ring injury (AIS(PELVIS)>2). In 131 cases (34%), the injuries were further classified (Pennal and Tile) and a technical reconstruction made of the accident: 52% were type A, 27% type B and 21% type C injuries; 46% were in cars, 12% on motorised two-wheelers, 10% on bicycles and 1% in utility vehicles; 31% were pedestrians. Pelvic-ring injuries occurred in restrained vehicle occupants in accidents with a (delta)V of more than 30 km/h, whereas they occurred in a considerable proportion of unrestrained vehicle occupants, pedestrians and bicyclists at lower (delta)V or collision speed. The percentage of B- and C-type injuries increased in crashes with higher (delta)v or collision speed. In addition to further improvements of the passive safety, lower collision speeds or (delta)V would reduce or prevent pelvic-ring injuries. Due to the small number of occupants protected by airbags in this study, their protective effect for the pelvis could not be assessed. The reconstruction of pelvic-ring injury mechanism in traffic accidents is possible when technical and medical factors are considered.
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Definitions of shock types. Hypovolaemic shock is a state of insufficient perfusion of vital organs with consecutive imbalance of oxygen supply and demand due to an intravascular volume deficiency with critically impaired cardiac preload. Subtypes are haemorrhagic shock, hypovolaemic shock in the narrow sense, traumatic-haemorrhagic shock and traumatic-hypovolaemic shock. Cardiac shock is caused by a primary critical cardiac pump failure with consecutive inadequate oxygen supply of the organism. Anaphylactic shock is an acute failure of blood volume distribution (distributive shock) and caused by IgE-dependent, type-I-allergic, classical hypersensibility, or a physically, chemically, or osmotically induced IgE-independent anaphylactoid hypersensibility. The septic shock is a sepsis-induced distribution failure of the circulating blood volume in the sense of a distributive shock. The neurogenic shock is a distributive shock induced by generalized and extensive vasodilatation with consecutive hypovolaemia due to an imbalance of sympathetic and parasympathetic regulation of vascular smooth muscles.
OBJECTIVE: To investigate the incidence and distribution of heterotopic ossifications in patients with blunt multiple trauma with and without associated head trauma. DESIGN: Retrospective. SETTING: Level I trauma center. PATIENTS: Patients were included if they were treated between August 1987 and September 1995. Inclusion criteria included age between 16 and 65 years, injury severity score (ISS) of more than twenty points, and clinical reexamination performed more than three years after the initial injury. METHODS: The records of each patient were abstracted to determine the ISS, the Glasgow coma score (GCS), and parameters describing the course of intensive care. For each patient, a reexamination was performed between January and September 1998. Patients with multiple trauma and associated head trauma (Group PTH, polytrauma, GCS less than nine points, and head computed tomography scan abnormalities) and patients with multiple trauma without associated head trauma (Group PT, polytrauma, GCS of at least nine points, and normal head computed tomography scans) were compared. A clinical reexamination was performed to evaluate functional outcome. RESULTS: Sixty-four patients belonged to Group PTH and 124 patients belonged to Group PT. There were no differences in the age (Group PTH, 28.9 +/- 1.6 years; Group PT, 29.2 +/- 2.1 years) or severity of injury (ISS Group PTH, 31.0 +/- 5.3 points; ISS Group PT, 33.0 +/- 6.1 points) among patients in the two groups. The overall incidence of periarticular heterotopic ossification was comparable in patients with multiple trauma with and without head injury (Group PTH, 30 of 64 patients [46.9 percent]; Group PT, 53 of 124 patients [42.7 percent]). The duration of ventilation was significantly higher in Group PT (Group PTH, 9.3 +/- 2.4 days; Group PT, 14.2 +/- 3.1 days; p = 0.02). In the subgroups in which heterotopic ossification developed (PT-HO and PTH-HO), patients in PT-HO had a significantly higher incidence of heterotopic ossification, as compared with patients in PTH-HO at initially uninjured joints (Group PTH-HO, 1 of 30 patients [3.3 percent]; Group PT-HO, 10 of 53 patients [18.9 percent]; p = 0.04). CONCLUSIONS: There was a high incidence of heterotopic ossification around those joints that were initially classified as uninjured in patients without head trauma. This finding suggests that pathogenic pathways independent of head trauma, such as long-term ventilation, play a main role. Causative factors for the development of heterotopic ossification at initially uninjured joints in long-term ventilated patients with multiple trauma with and without head trauma remain to be elucidated.
BACKGROUND: The aim of this study is to assess the associations between the timing of secondary definitive fracture surgery on inflammatory changes and outcome in the patient with multiple injuries. The study population consists of a series of patients with multiple injuries who were managed using a strategy of primary temporary skeletal stabilization followed by delayed definitive fracture fixation. METHODS: In a prospective cohort study performed at a Level I trauma center, the patients' injuries and operative details as well as immune markers and clinical outcomes were studied. The patients were split into an early secondary surgery group (group ESS, surgery at days 2-4) and a late secondary surgery group (group LSS, surgery at days 5-8). During the posttraumatic course, inflammatory markers (interleukin [IL]-6, tumor necrosis factor-alpha) were determined on a daily basis. Perioperatively, these markers were additionally evaluated at 30 minutes, 7 hours, and 24 hours after initiation of surgery. RESULTS: Secondary surgery on days 2 to 4 was associated with a higher incidence of postoperative organ dysfunction (n = 33 [46.5%]) than secondary surgery on days 5 to 8 (n = 9 [15.7%], p = 0.01). A significant association between the combination of initial IL-6 values > 500 pg/dL plus surgery on days 2 to 4 and the development of multiple organ failure (r = 0.96, p < 0.001) occurred. A correlation between the initial IL-6 values > 500 pg/dL and surgery on days 5 to 8 (r = 0.57, p < 0.07) could not be found. IL-6 also demonstrated a predictive value for the development of multiple organ failure: IL-6 > 500 pg/dL in group ESS, r = 0.96, p < 0.001; IL-6 > 500 pg/dL in group LSS, r = 0.57, p < 0.07. CONCLUSION: According to our data, no distinct clinical advantage in carrying out secondary definitive fracture fixation early could be determined. In contrast, in patients who demonstrated initial IL-6 values above 500 pg/dL, it may be advantageous to delay the interval between primary temporary fracture stabilization and secondary definitive fracture fixation for more than 4 days. In patients with blunt multiple injuries undergoing primary temporary fixation of major fractures, the timing of secondary definitive surgery should be carefully selected, because it may act as a second hit phenomenon and cause a deterioration of the clinical status.
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During 1985 and 1993, 7,410 persons were injured in traffic accidents in the area of Hanover. Of these, 306 (4.1%) sustained a pelvic girdle injury. In 139 cases (45%), the pelvic girdle injuries were further classified (Pennal and Tile) and a technical reconstruction of the accident situation was performed. 52% were type A, 27% type B and 21% type C injuries. Some 47% of the casualties were vehicle occupants, 31% pedestrians, 12% motorcyclists and 10% cyclists. In restrained vehicle occupants pelvic girdle injuries occurred mostly in accidents with a delta-v of more than 30 km/h, whereas in unrestrained vehicle occupants, pedestrians and cyclists they also occurred with lower delta-v or collision speed. The percentage of type B and C injuries increased with higher velocities. In addition to further improvements in passive safety, lower collision speed or delta-v is necessary to reduce or prevent pelvic girdle injuries. The reconstruction of pelvic girdle injury mechanism in traffic accidents is possible, when both technical and medical parameters are considered.