Abstracts Unfallchirurg 2006 · 109:348–350 DOI 10.1007/s00113-006-1072-y © Springer Medizin Verlag 2006

Journal of Orthopaedic Trauma (2005) 19(9):597-603 Gardner, Michael J; Brophy, Robert H; Campbell, Deirdre M; Mahajan, Amit; Wright, Timothy M; Helfet, David L; Lorich, Dean G The Mechanical Behavior of Locking Compression Plates Compared With Dynamic Compression Plates in a Cadaver Radius Model Objective: The purpose of this cadaveric study was to compare the mechanical behavior of a locked compression plate, which uses threaded screw heads to create a fixed angle construct, with a dynamic compression plate construct in a cadaver radius model. Design: Mechanical study with cyclic testing and high-speed optical motion analysis. Setting: Biomechanics laboratory at an academic institution. Patients/Participants: Eighteen pairs of fresh-frozen human cadaver radii were divided into 3 groups of 6 to be tested as a group in each of the following force Applications: anteroposterior (AP) bending, mediolateral bending, or torsion. Intervention: Each bone was osteotomized leaving a 5-mm fracture gap and then fixed with a plate. For each pair, 1 radius received a standard plate (limited-contact dynamic compression plates; LC-DCP), the contralateral radius was fixed with a locking compression plate (LCP), and specimens underwent cyclic loading. Normalized stiffness, average energy absorbed, and Newton-cycles to failure were calculated. In addition, a 3-dimensional, high-speed, infrared motion analysis system was used to evaluate motion at the fracture site. Main Outcome Measurements: Construct stiffness, fracture site motion, cycles to failure, and energy absorption. Repeated measures ANOVA were used to detect differences between groups with time. Results: In the torsion group, LCP specimens failed at 60% greater Newton-cycles than the LC-DCP (1473 vs. 918; P < 0.05). In the AP group, the LC-DCP absorbed significantly greater energy during 10,000 cycles compared with the LCP group (P < 0.05). The 2 constructs demonstrated different biomechanical behavior with time. As cycling progressed in the LC-DCP specimens under torsion testing, stiffness (measured at the actuator at the bone ends) did not change significantly; however, fracture motion (measured at the fracture surfaces) decreased significantly (P = 0.04). The LCP specimens did not display similar behavior. Conclusions: Our findings indicated that LCP constructs may demonstrate subtle mechanical superiority compared with the LC-DCP. The LCP specimens had less energy absorption in the AP group and survived longer in the torsion group. Discordance of motion between measurement regions was observed only in the LC-DCP torsion group, and may have been caused by plate-bone slippage or bone-screw subcatastrophic failure. However, many other compared parameters were found to be similar, and the clinical significance of the few differences found between constructs mandates further investigation. Journal of Orthopaedic Trauma (2005) 19(9):604-609 Jenkinson, Richard J; Sanders, David W; Macleod, Mark D; Domonkos, Andrea; Lydestadt, Jeanette RN Intraoperative Diagnosis of Syndesmosis Injuries in External Rotation Ankle Fractures Objective: This study was designed to compare intraoperative fluoroscopic stress testing, static radiographs, and biomechanical criteria for the diagnosis of distal tibiofibular syndesmotic instability associated with external rotation type ankle fractures.

348 |

Der Unfallchirurg 4 · 2006

Design: Prospective, consecutive series. Setting: Academic level 1 trauma center. Patients/Participants: Thirty-eight skeletally mature patients with unstable unilateral external rotation ankle fractures were prospectively recruited. Intervention: Before surgery, the treating surgeon detailed the operative treatment plan, including need for syndesmotic fixation. In pronation-external rotation injuries, biomechanical criteria were applied to predict syndesmotic instability. Ankles were examined using intraoperative fluoroscopic external rotation stress tests. The contralateral uninjured limb was used as a control. A 7.2-Nm force was applied for the external rotation stress examination. Stress testing was performed after lateral malleolar fixation and repeated after medial and syndesmotic fixation. Main Outcome Measures: The incidence of syndesmotic instability was determined based on radiographic clear space measurements and compared with previously published criteria. Results: Intraoperative fluoroscopy detected unpredicted syndesmotic instability in 37% of ankles. In supination-external rotation (OTA 44B) injuries, unpredicted syndesmosis instability was found in 10 of 30 patients (33%). In pronation-external rotation injuries (OTA 44C), 4 of 7 patients (57%) were associated with syndesmosis disruption not predicted by biomechanical criteria. In bimalleolar fractures, syndesmosis fixation improved stability compared with rigid bimalleolar fixation alone (P < 0.01). Conclusions: Preoperative radiographs and biomechanical criteria are unable to routinely predict the presence or absence of syndesmosis instability. Rigid bimalleolar fixation was frequently not sufficient to stabilize syndesmotic disruption. Intraoperative stress fluoroscopy is a valuable tool for detection of unstable syndesmotic injuries. Journal of Orthopaedic Trauma (2005) 19(9):623-628 Sanders, Michael B; Starr, Adam J; Frawley, William H; McNulty, Michael J; Niacaris, Timothy R Posttraumatic Stress Symptoms in Children Recovering From Minor Orthopaedic Injury and Treatment Background: This study was designed to determine the prevalence of high levels of posttraumatic stress disorder (PTSD) symptoms among pediatric orthopaedic trauma patients recovering from injury and to see whether injury or demographic variables are associated with the presence of the symptoms. Methods: Four hundred pediatric orthopaedic trauma patients completed the Child PTSD Symptom Scale questionnaire. Demographic and injury variables were tested to see if any were associated with the presence of high levels of posttraumatic stress symptoms. Results: The average age of respondents was 11 years. The average time since injury was 36 days. The mean Injury Severity Score and summed Extremity Abbreviated Injury Score were 4 and 2, respectively. A total of 130 (33%) met criteria for high levels of PTSD symptoms. None of the variables tested were associated with high levels of PTSD symptoms, except one. Patients admitted to the hospital after injury were significantly more likely to develop high levels of PTSD symptoms. Conclusions: High levels of posttraumatic stress disorder symptoms are common in the recovery period after pediatric orthopaedic trauma, even among patients with relatively minor injury. Children admitted to the hospital after injury are at higher risk for such symptoms.