[Stability of volar fixed-angle plating for distal radius fractures. Failure modes in osteoporotic bone]. / Die Stabilität von distalen Radiusfrakturen mit volaren winkelstabilen Plattenosteosynthesen. Versagensmechanismen im osteoporotischen Knochen.

BACKGROUND: Distal radius fractures continue to show significant complication rates after operative treatment with locked plating. Failure occurs by screw loosening or screw penetration in the distal fragment. Placement of additional screws may enhance the stiffness of fracture fixation. The aim of this study was to determine the fatigue properties of different screw configurations in distal radius plate osteosynthesis with biomechanical tests and finite element analysis (FEA). MATERIAL AND METHODS: Unstable distal radius fractures were created in 12 human cadaveric bone specimens and were fixed with volar locking plates. Group 4SC was fixed with four screws in the distal row and group 6SC with two additional screws the row below. Dynamic loading was applied physiologically. The radial shortening, the angulation of the distal fragment and the failure mechanism were determined by experimental tests and were further elucidated by FEA. RESULTS: Group 6SC showed a significantly lower radial shortening and inclination. Breakage of the screws within the plate was noted in group 4SC, while moderate screw penetration was observed in group 6SC. FEA confirmed the biomechanical tests. In group 4SC elevated von Mises strain in the locking mechanism explained the inclination of the screws and the distal fragment. The elastic strain in group 6SC was increased at the screw-bone interface which explained the resulting screw penetration. CONCLUSION: The failure mechanism in volar plating of distal radius fractures depended on the number of screws and their configuration. Using two more screws increases construct stiffness and angular stability under dynamic loading. However, increased stiffness also promoted screw penetration mainly in osteoporotic bone. Compared to screw penetration, loss of reposition and inclination of the distal fragment observed in the 4SC configuration is more likely to result in clinical complications.

Distal radius fracture fixation with volar locking plates and additional bone augmentation in osteoporotic bone: a biomechanical study in a cadaveric model.

BACKGROUND: Fractures of the distal radius represent the most common fractures in adults. Volar locked plating has become a popular method for treating these fractures, but has been subject to several shortcomings in osteoporotic bone, such as loss of reduction and screw purchase. In order to overcome these shortcomings, cement augmentation has been proposed. METHODS: AO-type 23-A3.3 fractures were made in 8 pairs of fresh frozen osteoporotic cadaveric radial bones. All specimens were treated with volar plating, and divided into cement augmentation or non-augmentation groups (n = 8/group). Constructs were tested dynamically and load to failure, construct-stiffness, fracture gap movement and screw cutting distance were measured. RESULTS: Cement augmentation resulted in a significant increase in cycles and load to failure, as well as construct stiffness at loads higher than 325 N. When compared to the non-augmented group, fracture gap movement decreased significantly at this load and higher, as did screw cutting distance at the holes of the ulnar column. The cycles to failure depend on the BMD in the distal region of the radius. CONCLUSION: Cement augmentation improves biomechanical properties in volar plating of the distal radius.

Biomechanical comparison of locked plate osteosynthesis, reamed and unreamed nailing in conventional interlocking technique, and unreamed angle stable nailing in distal tibia fractures.

INTRODUCTION: The treatment of distal tibia shaft fractures is still problematic because of the thin soft tissue envelope and less stable osteosynthesis. Therefore, nonunions are often seen in this region. When reamed nailing is performed, construct stiffness can be increased and fracture gap movement can be reduced, but in open fractures the question whether reamed nailing is before unreamed nailing is still uncertain. Therefore, unreamed nails with angle stable interlocking options were produced with the idea to improve the biomechanical properties of unreamed nails. This study compared reamed and unreamed nailing either with angle stable or conventional interlocking to plate osteosynthesis. The hypothesis was that angular stability in unreamed nailing will increase the construct stiffness and reduce the fracture gap movement. METHODS: In this study, four groups of five artificial tibiae were treated with different osteosynthesis techniques. Group 1 was treated with a reamed nailing technique, group 2 with a distally angle stable locked nail in an unreamed technique, group 3 with an unreamed nail in a conventional locking technique, and group 4 with a locked medial plate system. After osteotomy of the intersection of the distal 4/5 to 5/5 of the tibia, stiffness of the implant-bone construct and micromovement of the fragments were measured. In addition, the range of motion at the mechanical zero under torsional load was calculated. RESULTS: Biomechanical tests showed that the stiffness of the reamed nail constructs was significantly higher than the compared implants. The unreamed conventionally locked nail and unreamed distally angular stable locked nails were less stiff than the larger sized reamed nail, but the implant-bone construct showed higher stiffness values than the locked plate osteosynthesis. Regarding stiffness of the two unreamed groups, no significant differences were found. The interfragmentary movement in axial and torsional force exhibited the highest range of motion for locked plating, while the reamed nail significantly exhibited the least. The range of motion at the mechanical zero under torsional load was the lowest for the unreamed and angle stable locked nail. CONCLUSIONS: Under biomechanical considerations, the treatment of distal tibia fractures using the reamed nailing technique is before unreamed nailing, but distal angle stable interlocking of the nail may also be a satisfactory method.

Biomechanical comparison of two locking plate systems for the distal tibia.

BACKGROUND: Distal tibia fractures are known to be difficult to stabilize and nonunions often occur because of a relative instability of the fragments. Therefore, it was of interest to ascertain how different locking plates behave regarding stiffness and interfragmentary movement in comminuted distal tibia fractures. METHODS: A locked medial plate (AxSOS) for the medial distal tibia and a locked medial plate (LCP) for the distal medial tibia were compared biomechanically under compression and torsional load. The tibiae were osteotomized in distal intersection between 4/5 and 5/5, with a gap of 10 mm after instrumentation. For compression force, a load of 350 N was applied and for torsion, a torque of 0-10 Nm and back to 0 over -5-Nm intervals was performed. Stiffness was calculated from the machine data and interfragmentary movement was measured with an optoelectronic measurement device. RESULTS: Under compression load, the stiffness showed no significant differences between the AxSOS plate compared to the LCP. Significant differences were seen in the interfragmentary movement, where the LCP showed 1.03 mm compared to 0.6 mm for the AxSOS plate. In torsional testing, the AxSOS plate showed significantly higher stiffness than the LCP. The AxSOS plate and the LCP showed similar values for interfragmentary movement under torsional load. CONCLUSION: The treatment of distal tibia fractures with angle-stable medial AxSOS plate showed less interfragmentary movement and higher stiffness than fracture fixation with a locked medial LCP. Even if there are no significant differences in torsional testing, plating of the distal tibia should be performed with a steel plate from the biomechanical view.

[Gunshot injuries--incidence and treatment]. / Schussverletzungen--ihre Inzidenz und Versorgung.

BACKGROUND: Gunshot injuries are very rare in the European Union. To show the requirements for the trauma surgeon to deal with gunshot injuries this analysis was performed. METHODS: Gunshot injuries seen at Lorenz Boehler Trauma Center from 1997 to 2004 were reviewed. The case histories of 67 patients were analysed for the cause of the gunshot injury, type of weapon, surgical intervention, days of treatment and outcome. RESULTS: The most commonly cause of gunshot injuries were criminal offenses (n = 35). Handguns were used most often (n = 32). The locations of injuries were evenly distributed over head (n = 18 ), trunk (n = 16), upper (n = 15) and lower limb (n = 18). Surgical treatment was performed in 57 patients. The median stay on ICU was 10 days. 6 patients died. CONCLUSION: Gunshot injuries are frequently not confined to the extremities. The challenge for the trauma surgeon is to deal with injuries of the head, chest and abdomen.

Characteristics of polytrauma patients between 1992 and 2002: what is changing?

OBJECTIVE: To analyse the characteristics of polytrauma patients and the quality and progress of treatment regimens by an evaluation of a trauma population. METHODS: The study included all polytrauma patients treated between 1992 and 2002 at a level 1 trauma centre. Data of 501 cases were collected prospectively and analysed retrospectively. The analysis included the demographic data, injury severity, preclinical haemodynamics, intubation rates, incidences of multiorgan failure and adult respiratory distress syndrome, and mortality. RESULTS: Per year of the study, the average age of patients increased by 0.748 years. Preclinical intubation rates also increased and the number of cases of primary shock decreased. The Injury Severity Score fell on average by 0.59 points per year. There was a significant decrease in multiorgan failure and adult respiratory distress syndrome. The mortality rate remained constant. CONCLUSIONS: Protracted time of initial rescue, early intubation and good preclinical treatment lead to a reduction of complications during intensive care. The increasing number of elderly patients results in persistently high mortality even with decreasing injury severity.

[Long-term results in the treatment of foot injuries in polytraumatized patients]. / Langzeitergebnisse in der Behandlung von Fussverletzungen bei polytraumatisierten Patienten.

INTRODUCTION: The aim of this study was to evaluate the long-term outcome of multiple injured patients with foot injuries. While severity and frequency of multiple injuries could be decreased in the last years, it was not possible to decrease the severity of injuries of the foot and ankle region. These injuries are often not detected and their severity is underestimated in primarily diagnostics what might lead to complaints in the longterm course. METHODS: The multiple trauma database of the Department of Traumatology of the University of Vienna includes 386 patients from September 1992 to April 2001. 40 (10.4 %) of these patients suffered a fracture or dislocation of foot or ankle. 33 (82.5 %) multiple injured patients with injuries of foot or ankle could be reexamined between April and September 2002 and the longterm outcome of the foot and ankle region could be evaluated objectively and subjectively. RESULTS: 22 (66.7 %) patients were male, 11 (33.3 %) female. The mean age was 34.5 years. 27 (81.8 %) patients still suffered from complaints related to their injured foot and ankle region. After calculation of the AOFAS these complaints were predominantly located in the ankle-hindfoot region. 22 (66.7 %) patients had to limit their sports activity. DISCUSSION: In our study period an increasing number and severity of injuries of foot or ankle can be shown. Furthermore multiple injured patients with concomitant injuries of foot or ankle show a lower ISS what suggests that these patients might have a higher survival rate and consecutively enter rehabilitation process.

[Polytrauma and air rescue. A retrospective analysis of trauma care in eastern Austria exemplified by an urban trauma center]. / Polytrauma und Luftrettung. Eine retrospektive Analyse der Versorgung im Osten Osterreichs am Beispiel eines urbanen Traumazentrums.

OBJECTIVE: The aim of this study was a retrospective analysis of polytraumatized patients who were treated by a helicopter emergency medical service (HEMS) crew. This study was performed to evaluate the level of prehospital care provided for severely injured patients. Special consideration was given to treatment strategies of specific injuries which led to multiple injuries, defined as "polytrauma." METHODS: From September 1992 to April 2001 data of 386 patients treated in the Department of Traumatology of the University of Vienna were collected. A total of 104 patients (26.9%) were transported by helicopter directly from the accident scene. This collective was analyzed demographically; relevant prehospital data such as therapeutic interventions and the early clinical course were examined. RESULTS: The mean Injury Severity Score (ISS) was 36.9: 70 (67.3%) patients were male and 34 (32.7%) female; the median age was 36.1 years. Traffic accidents were the most frequent trauma mechanism (78.9%) followed by falls from height (17.3%). The mean period between trauma and trauma emergency room was 0.73 h; 77 (74.0%) patients were intubated and mechanically ventilated at the scene and all patients received analgosedation. The mean preclinical fluid load was 1673 ml. The mean duration of treatment in the emergency room was 53 min. The mean length of intensive care was 8.6 days and the mortality rate was 19.2% within the first 24 h. CONCLUSION: Major trauma is an important cause for requesting a primary HEMS mission. As the results of this study show, immediate and invasive interventions at the scene lead to an improvement of vital functions at admission. For the patients' further course of treatment, the choice of a trauma center seems to be important, too.