Tim Pohlemann

The Hannover experience in management of pelvic fractures

Between 1972 and 1993, 1899 patients with fractures of the pelvis were treated at the authors institution. The pelvic ring was fractured in 1479 patients, and 1029 sustained polytrauma. A retrospective study included four parts: (1) Demographic analysis of 1409 patients showed an increase in the severity of pelvic and general trauma during this period. The 17.7% mortality rate was predicted by the Hannover Polytrauma Score and associated extrapelvic blunt trauma. (2) Residual displacement after operative treatment of the pelvis was analyzed in 221 patients. In C type (Tile) fractures residual displacement correlated with external fixation and solely anterior stabilization. (3) Outcome after operative treatment was analyzed in a consecutive series of 58 patients an average of 2.2 years after trauma. Pelvic pain was frequent (Type B 11%, Type C 66%) and correlated with posterior displacement over 5 mm and primary neurological injuries. (4) Mortality after complex pelvic trauma (pelvic fracture with soft tissue injury) decreased from 48.1% to 29.6% during these years. Standardized protocols for primary care and operative procedures of pelvic injuries optimize therapy. Complex pelvic trauma requires early, aggressive surgical management with surgical hemostasis. Further developments in open reduction and internal fixation of the pelvis focus on minimizing additional soft tissue trauma and implants.

Blunt abdominal trauma in cases of multiple trauma evaluated by ultrasonography: a prospective analysis of 291 patients.

Early recognition of blunt abdominal trauma in patients with multiple injuries and in shock is of utmost importance and calls for a rapid screening method. The reliability of diagnostic ultrasonography in detecting hemoperitoneum in patients with multiple trauma was evaluated prospectively. From 1986 to 1990, 291 patients with severe multiple injuries (ISS greater than 20, mean ISS 31.2) were included in the study. Laparotomy was performed on 117 patients (40%). Initial ultrasound (US) findings showed a sensitivity, specificity, and accuracy of 89%, 97%, and 94%, respectively, in detecting intra-abdominal injuries requiring surgical repair. The positive and negative predictive values were 94% and 95%, respectively. A standardized management of frequent repeat US studies can even improve on these numbers. In our department ultrasonography has replaced diagnostic peritoneal lavage (DPL) as the diagnostic study of first choice. Diagnostic peritoneal lavage is reserved for selected cases only.

Survival trends and predictors of mortality in severe pelvic trauma: Estimates from the German Pelvic Trauma Registry Initiative

STUDY OBJECTIVE To determine longitudinal trends in mortality, and the contribution of specific injury characteristics and treatment modalities to the risk of a fatal outcome after severe and complex pelvic trauma. METHODS We studied 5048 patients with pelvic ring fractures enrolled in the German Pelvic Trauma Registry Initiative between 1991 and 1993, 1998 and 2000, and 2004 and 2006. Complete datasets were available for 5014 cases, including 508 complex injuries, defined as unstable fractures with severe peri-pelvic soft tissue and organ laceration. Multivariable mixed-effects logistic regression analysis was employed to evaluate the impact of demographic, injury- and treatment-associated variables on all-cause in-hospital mortality. RESULTS All-cause in-hospital mortality declined from 8% (39/466) in 1991 to 5% (33/638) in 2006. Controlling for age, Injury Severity Score, pelvic vessel injury, the need for emergency laparotomy, and application of a pelvic clamp, the odds ratio (OR) per annum was 0.94 (95% confidence interval [CI] 0.91-0.96). However, the risk of death did not decrease significantly in patients with complex injuries (OR 0.98, 95% CI 0.93-1.03). Raw mortality associated with this type of injury was 18% (95% CI 9-32%) in 2006. CONCLUSION In contrast to an overall decline in trauma mortality, complex pelvic ring injuries remain associated with a significant risk of death. Awareness of this potentially life-threatening condition should be increased amongst trauma care professionals, and early management protocols need to be implemented to improve the survival prognosis.

Internal fixation of multiple fractures in patients with polytrauma.

Within the last decade understanding of the pathogenetic consequences of trauma has been improved significantly. An additional reduction of lethality has been achieved that in part is related to increasing discrimination of complex injury patterns. Accordingly, additional staging in fracture management of these injuries has been developed. An overview of the current status of fracture management in polytrauma is given and certain regimens that are still controversially are discussed. The principles determined are based on the treatment experience of 4003 multiply injured patients within the past 23 years. The most important principles within the first hours after trauma represent adequate hemorrhage control. In fracture treatment the primary goal remains to perform primary stable osteosynthesis. In severe polytrauma with severe injuries to the extremities, the first decision is whether limb salvage can be achieved without risk of deterioration of the patients condition. If this is the case, open fractures Grades III b and c usually can be stabilized primarily by unreamed intramedullary nailing or percutaneous plating. The priority pattern in multiple closed fractures is as follows: (1) tibia; (2) femur; (3) pelvis; (4) spine; and (5) upper extremity. Exceptions may ensue if severe head or thoracic trauma is present. Delayed treatment is performed for complex joint reconstruction, definitive treatment of maxillofacial injuries, and soft tissue reconstruction.

New indications for computer-assisted surgery: tumor resection in the pelvis.

The resection of recurrent malignant pelvic tumors was supported by a commercially available navigation system in three patients. Preoperatively three-dimensional images from the pelvis were obtained by computed tomography or magnetic resonance imaging to identify the tumor extension. During surgery navigated tools oriented the surgeon to excise the tumor with adequate virtual margins. Navigation was helpful for tumor identification in one patient with a recurrent presacral mesenchymal chondrosarcoma. In the other two patients the tumor resection in the bone was done with three-dimensional observation of the osteotomies in the sacrum. In all three patients the histopathologic analysis confirmed that the neoplasms were excised accurately within their margins. We think that computer-assisted surgery is a potential method to increase the accuracy of tumor resections.

The liquid overlay technique is the key to formation of co-culture spheroids consisting of primary osteoblasts, fibroblasts and endothelial cells.

BACKGROUND AIMS The 3-dimensional (3-D) culture of various cell types reflects the in vivo situation more precisely than 2-dimensional (2-D) cell culture techniques. Spheroids as 3-D cell constructs have been used in tumor research for a long time. They have also been used to study angiogenic mechanisms, which are essential for the success of many tissue-engineering approaches. Several methods of forming spheroids are known, but there is a lack of systematic studies evaluating the performance of these techniques. METHODS We evaluated the performance of the hanging drop technique, carboxymethyl cellulose technique and liquid overlay technique to form both mono- and co-culture spheroids consisting of primary osteoblasts, fibroblasts and endothelial cells. The performance of the three techniques was evaluated in terms of rate of yield and reproducibility. The size of the generated spheroids was determined systematically. RESULTS The liquid overlay technique was the most suitable for generating spheroids reproducibly. The rate of yield for this technique was between 60% and 100% for monoculture spheroids and 100% for co-culture spheroids. The size of the spheroids could be adjusted easily and precisely by varying the number of seeded cells organized in one spheroid. The formation of co-culture spheroids consisting of three different cell types was possible. CONCLUSIONS Our results show that the most suitable technique for forming spheroids can vary from the chosen cell type, especially if primary cells are used. Co-culture spheroids consisting of three different cell types will be used to study angiogenic phenomena in further studies.

Advances in the establishment of defined mouse models for the study of fracture healing and bone regeneration.

The availability of a broad spectrum of antibodies and gene-targeted animals caused an increasing interest in mouse models for the study of molecular mechanisms of fracture healing and bone regeneration. In most murine fracture models, the tibia or the femur is fractured using a 3-point bending device (closed models) or is osteotomized using an open surgical approach (open models). For fracture studies in mice, the tibia has to be considered less appropriate compared with the femur because the stabilization of the fracture is more difficult due to its triangular, distally declining caliber and its bowed longitudinal axis. Biomechanical factors critically influence the bone healing process. Thus, the use of stable osteosynthesis techniques is also of interest in murine fracture models. To achieve stable fixation, several biomechanically standardized implants have recently been introduced, including a locking nail and an intramedullary compression screw. Other implants, such as a pin-clip, an external fixator, and a locking plate, additionally allow the stabilization of fractures with distinct gap sizes. This enables the study of healing of critical size defects and nonunions. The use of these implants further allows a rigid fixation of fractures in bridle bones, which is essential for fracture studies in animals suffering from metabolic bone diseases like osteoporosis. In general, the analysis of bone healing in these models includes different imaging techniques and histologic, immunohistochemical, biomechanical, and molecular methods. To evaluate the impact of different osteosynthesis techniques on physical activity and rehabilitation, gait analysis may additionally be performed. By this, the gait of the animals can be visualized and quantitatively analyzed using modified running wheels and dynamic high-resolution radiography systems. Taken together, a variety of different murine femur fracture models have become available, providing defined biomechanical conditions for fracture research. The use of these mouse models may now allow studying the influence of fracture stabilization techniques on molecular mechanisms of bone healing.

A new in vitro wound model based on the co-culture of human dermal microvascular endothelial cells and human dermal fibroblasts.

Background information. Different in vitro models, based on co‐culturing techniques, can be used to investigate the behaviour of cell types, which are relevant for human wound and soft‐tissue healing. Currently, no model exists to describe the behaviour of fibroblasts and microvascular endothelial cells under wound‐specific conditions. In order to develop a suitable in vitro model, we characterized co‐cultures comprising NHDFs (normal human dermal fibroblasts) and HDMECs (human dermal microvascular endothelial cells). The CCSWMA (co‐culture scratch wound migration assay) developed was supported by direct visualization techniques in order to investigate a broad spectrum of cellular parameters, such as migration and proliferation activity, the differentiation of NHDFs into MFs (myofibroblasts) and the expression of endothelin‐1 and ED‐A‐fibronectin (extra domain A fibronectin). The cellular response to hypoxia treatment, as one of the crucial conditions in wound healing, was monitored.

Computer-assisted fracture reduction of pelvic ring fractures: an in vitro study.

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° 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.

Pelvic fractures in Pregnant multiple trauma patients

OBJECTIVE To study the outcome of pelvic fractures and fetuses in pregnant patients involved in blunt multiple trauma. DESIGN Retrospective follow-up study. SETTING Level I trauma center. PATIENTS Pregnant multiple trauma patients with pelvic fractures between 1974 and 1998. INTERVENTIONS Conservative and operative treatment of pelvic fractures adapted to the clinical status of the mother. MAIN OUTCOME MEASURES Clinical, functional, and social outcomes were evaluated. RESULTS Out of 4,196 patients with blunt multiple trauma treated between 1974 and June 1998, seven demonstrated the combination of blunt multiple trauma, pregnancy, and pelvic fractures. These patients had a mean Injury Severity Score of 29.9 points. Five mothers and three fetuses survived their injuries. All dead fetuses died on the scene. One surviving fetus was found to have hydrocephalus unrelated to the injury; the remaining fetuses had an uneventful delivery and were healthy. In two of the three patients whose fetuses survived, the treatment of the pelvic fracture was modified for the sake of fetal well-being. In all of these patients, acceptable outcome was achieved. CONCLUSION Modification of the treatment of the pelvic fracture in pregnant women with multiple trauma may be necessary to minimize the risk of fetal injury. In our experience with these rare cases, this modified treatment did not severely alter the clinical outcome of the mothers pelvic fracture.