Validity and Clinical Consequences of a Rotational Mechanism for Slipped Capital Femoral Epiphysis.

BACKGROUND: Recent anatomic data supports a mechanism for slipped capital femoral epiphysis (SCFE) where the metaphysis rotates on the epiphysis through the eccentrically located epiphyseal tubercle as a pivot. The validity of such a mechanism and its clinical consequences have not been well investigated. METHODS: This cadaveric study defined the normal location of the calcar ridge line in 100 paired femora and compared them with 11 SCFE specimens, and with 25 immature femora where the metaphysis was rotated 30, 60, and 90 degrees on the epiphysis to model progressive SCFE. Coronal, sagittal, and axial plane deformity were measured on the rotational model to define the characteristic deformity caused by rotation, and lateral epiphyseal foramina stretch was measured to quantify the protective effect of an eccentric pivot. RESULTS: The posterior displacement of the fovea with respect to the calcar ridge line was 1±5 mm for the controls, versus 23±10 mm for the SCFE specimens (P<0.0005), and posterior displacement increased with incremental rotation in the rotational model (P<0.0005). The rotational model found minimal varus deformity, but substantial extension and retroversion, with deformities of 0±5, -16±12, and -38±9 degrees, respectively, at 90 degrees of rotation. The eccentric pivot mitigated lateral epiphyseal vessel stretch by 55% to 70%. CONCLUSIONS: This study provides strong anatomic support for a rotational mechanism for stable SCFE. When the metaphysis is rotated on the epiphysis acutely, minimal varus deformity is created, while substantial retroversion occurs. As this rotation occurs the eccentric pivot protects the lateral epiphyseal vessels, and likely accounts for the low rate of avascular necrosis observed in stable SCFE. CLINICAL RELEVANCE: If SCFE is treated in an open manner then the presence of a chronic rotational deformity should be considered. When planning osteotomies for deformity after a stable SCFE, any suspected varus component should be carefully investigated as it may represent retroversion deformity brought into view by external rotation posturing of the leg.

Implementation of a military-derived damage-control resuscitation strategy in a civilian trauma center decreases acute hypoxia in massively transfused patients.

BACKGROUND: Recent military experience supports a paradigm shift in shock resuscitation to damage-control resuscitation (DCR), which emphasizes a plasma-rich and crystalloid-poor approach to resuscitation. The effect of DCR on hypoxia after massive transfusion is unknown. We hypothesized that implementation of a military-derived DCR strategy in a civilian setting would lead to decreased acute hypoxia. METHODS: A DCR strategy was implemented in 2007. We retrospectively reviewed patients receiving trauma surgeon operative intervention and 10 or more units of packed red blood cells (pRBCs) within 24 hours of injury at an adult Level I trauma center from 2001 to 2010. Demographic data, blood requirements, and PaO2/FIO2 ratios were analyzed. To evaluate evolving resuscitation strategies, we fit linear trend models to continuous variables and tested their slopes for statistical significance. RESULTS: Two hundred sixteen patients met the study criteria, with a mean age of 35 ± 1.1 years and Injury Severity Score (ISS) of 31 ± 9.0. Of the patients, 80% were male, and 52% sustained penetrating injuries. Overall mortality was 32%. Overall mean pRBC and fresh frozen plasma (FFP) units infused in 24 hours were 23.2 ± 1.1 and 18.6 ± 1.1, respectively. Trends for patient age, sex, mechanism of injury, ISS, highest positive end-expiratory pressure, and mean total pRBC transfused over 24 hours were not statistically different from zero. An increasing trend in FFP and platelets transfused during the first 24 hours (p < 0.0001, p = 0.04, respectively) and a decrease in the pRBC/FFP ratio (p < 0.0001) were found. The amount of crystalloid infused during the initial 24 hours decreased with time (p < 0.0001). The lowest PaO2/FIO2 ratio recorded during the initial 24 hours increased during the study period (p = 0.01), indicating a statistically significant reduction in hypoxia. CONCLUSION: A military-derived DCR strategy can be implemented in the civilian setting. DCR led to significant increases in FFP transfusion, decreases in crystalloid use, and acute hypoxia.