Prism S. Schneider

Early Mechanical Failures of the Synthes Variable Angle Locking Distal Femur Plate.

Objectives: To document the high failure rate of a specific implant: the Synthes Variable Angle (VA) Locking Distal Femur Plate. Design: Retrospective. Setting: Urban University Level I Trauma Center. Patient/Participants: All distal femur fractures (OTA/AO 33-A, B, C) treated from March 2011 through August 2013 were reviewed from our institutional orthopaedic trauma registry. Inclusion criteria were fractures treated with a precontoured distal femoral locking plate and age between 18 and 84. Exclusion criteria were fractures treated with intramedullary nails, arthroplasty, non-precontoured plates, dual plating, or screw fixation alone. The population was divided into 3 groups: less invasive stabilization system (LISS) group (n = 21), treated with LISS plates (Synthes, Paoli, PA); locking condylar plates (LCPs) group (n = 10), treated with LCPs (Synthes, Paoli, PA); and VA group (n = 36), treated with VA distal femoral LCPs (Synthes, Paoli, PA). Average age was 54.6 ± 17.5 years. Intervention: Open reduction internal fixation with one of the above implants was performed. Main Outcome Measures: The patients were followed radiographically for early mechanical implant failure defined as loosening of locking screws, loss of fixation, plate bending, or implant failure. Results: There were no statistically significant differences between groups for age, gender, open fracture, mechanism of injury, or medial comminution. There were 3 failures (14.3%) in group LISS, no failures (0%) in group LCP, and 8 failures (22.2%) in group VA. All 3 failures in group LISS were in A-type fractures (2 periprosthetic) and all failures in group VA were in C-type fractures. When all fractures for all 3 groups were compared for failure rate, there was no statistically significant difference (P = 0.23). However, when only 33-C fractures were compared, there was significantly greater failure rate in the VA group (P = 0.03). The mean time to failure in group VA was 147 days (range 24–401 days) and was significantly earlier (P = 0.034) when compared with group LISS (mean 356 days; range 251–433 days). Conclusions: Early mechanical failure with the VA distal femoral locking plate is higher than traditional locking plates (LCP and LISS) for OTA/AO 33-C fractures. We caution practicing surgeons against the use of this plate for metaphyseal fragmented distal femur fractures. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Can Thrombelastography Predict Venous Thromboembolic Events in Patients with Severe Extremity Trauma

Objectives: An elevated maximal amplitude (mA) value with rapid thrombelastography on admission can identify general trauma patients with an increased risk of venous thromboembolic events (VTEs). We hypothesized that (1) the risk of VTE traditionally assigned to injury lies specifically in those who sustain major orthopaedic trauma and (2) an elevated admission mA value could be used to identify patients with major orthopaedic injuries at risk for VTE during initial hospital admission. Design: Retrospective. Setting: University level 1 trauma center. Patients/Participants: Consecutive trauma patients admitted to an urban level 1 trauma center between September 2009 and February 2011 who met the criteria for level 1 trauma activation and who were between 18 and 85 years of age were included in our study group. Two groups were created, one whose extremity abbreviated injury severity score was 2 or greater (ORTHO) and the other whose extremity abbreviated injury severity score was <2 (non‐ORTHO). Main Outcome Measurements: Pulmonary emboli were confirmed by computed tomography angiography, and deep vein thromboses were confirmed by venous duplex. Univariate analyses were conducted and followed by purposeful regression analysis. Results: Of note, 1818 patients met the inclusion criteria (310 ORTHO and 1508 non‐ORTHO). Despite more hypocoagulable r‐TEG values on arrival (alpha angle 71 vs. 73 and mA 62 vs. 64, both P < 0.05), ORTHO patients had higher rates of VTE (6.5% vs. 2.7%, P < 0.001). Stepwise regression generated 4 values to predict development of VTE (age, male gender, white race, and ORTHO). After controlling for these variables, admission mA values >=65 (odds ratio 3.66) and >=72 (odds ratio 6.70) were independent predictors of VTEs during hospitalization. Conclusions: Admission rapid thrombelastography mA values can identify patients with major orthopaedic trauma injuries who present with an increased risk of in‐hospital deep vein thromboses and pulmonary embolism with a 3.6‐fold and 6.7‐fold increased risk for mA values >=65 and >=72, respectively. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Comparison of skin pressure measurements with the use of pelvic circumferential compression devices on pelvic ring injuries.

OBJECTIVES Pelvic circumferential compression devices are commonly used in the acute treatment of pelvic fractures for reduction of pelvic volume and initial stabilisation of the pelvic ring. There have been reports of catastrophic soft-tissue breakdown with their use. The aim of the current investigation was to determine whether various pelvic circumferential compression devices exert different amounts of pressure on the skin when applied with the force necessary to reduce the injury. The study hypothesis was that the device with the greatest surface area would have the lowest pressures on the soft-tissue. METHODS Rotationally unstable pelvic injuries (OTA type 61-B) were surgically created in five fresh, whole human cadavers. The amount of displacement at the pubic symphysis was measured using a Fastrak, three-dimensional, electromagnetic motion analysis device (Polhemus Inc., Colchester, VT). The T-POD, Pelvic Binder, Sam Sling, and circumferential sheet were applied in random order for testing. The devices were applied with enough force to obtain a reduction of less than 10mm of diastasis at the pubic symphysis. Pressure measurements, force required, and contact surface area were recorded with a Tekscan pressure mapping system. RESULTS The mean skin pressures observed ranged from 23 to 31kPa (173 to 233mm of Hg). The highest pressures were observed with the Sam Sling, but no statistically significant skin pressure differences were observed with any of the four devices (p>0.05). The Sam Sling also had the least mean contact area (590cm(2)). In greater than 70% of the trials, including all four devices tested, skin pressures exceeded what has been shown to be pressure high enough to cause skin breakdown (9.3kPa or 70mm of Hg). CONCLUSIONS Application of commercially available pelvic binders as well as circumferential sheeting commonly results in mean skin pressures that are considered to be above the threshold for skin breakdown. We therefore recommend that these devices only be used acutely, and definitive fixation or external fixation should be performed early as patient physiology allows. There may be some advantage of use of a simple sheet given its low cost, versatility, and ability to alter contact surface area.

Serum Mast Cell Tryptase as a Marker of Posttraumatic Joint Contracture in a Rabbit Model

OBJECTIVES Mast cells have been identified as key mediators of posttraumatic joint contracture, and stabilizing medications (ketotifen) have been shown to decrease contracture severity. Serum mast cell tryptase (SMCT) levels are used clinically to monitor mast cell-mediated conditions. The goals of this study were to determine if SMCT levels are elevated in the setting of joint contracture, if they can be decreased in association with ketotifen therapy, and if they correlate with contracture severity. METHODS This study used a previously developed rabbit model in which 39 animals were divided into 4 groups: operatively created joint contracture (ORC, n = 13), operatively created contracture treated with ketotifen at 2 doses (KF0.5, n = 9; KF1.0, n = 9), and healthy rabbits (NC, n = 8). Range of motion measures were performed at 8 weeks after the surgery. Serum samples were collected on postoperative days 1, 3, 5, 7, 21, 35, and 49. SMCT levels were measured using a rabbit-specific enzyme-linked immunosorbent assay. RESULTS Levels of SMCT were highest in the operatively created joint contracture group and were significantly greater compared with both ketotifen groups (P < 0.001). Levels were highest at postoperative day 1 with a trend to decrease over time. A positive correlation between SMCT levels and contracture severity was observed in all operative groups (P < 0.05). CONCLUSIONS Levels of SMCT are elevated in the setting of joint contracture, decreased in association with ketotifen therapy, and positively correlated with contracture severity. This is the first study to establish a relationship between SMCT and joint injury. Measurement of SMCT may be valuable in identifying those at risk of posttraumatic joint contracture.

The Effect of Cricoid Pressure on the Unstable Cervical Spine

BACKGROUND It has been proposed that cricoid pressure can exacerbate an unstable cervical injury and lead to neurologic deterioration. OBJECTIVE We sought to examine the amount of motion cricoid pressure could cause at an unstable subaxial cervical spine injury, and whether posterior manual support is of any benefit. METHODS Five fresh, whole cadavers had complete segmental instability at C5-C6 surgically created by a fellowship-trained spine surgeon. Cricoid pressure was applied to the anterior cricoid by an attending anesthesiologist. In addition, the effect of posterior cervical support was tested during the trials. The amount of angular and linear motion between C5 and C6 was measured using a Fastrak, three-dimensional, electromagnetic motion analysis device (Polhemus Inc., Colchester, VT). RESULTS When cricoid pressure is applied, the largest angular motion was 3 degrees and occurred in flexion-extension at C5-C6. The largest linear displacement was 1.36 mm and was in anterior-posterior displacement of C5-C6. When manual posterior cervical support was applied, the flexion-extension was improved to less than half this value (1.43 degrees), and this reached statistical significance (p = 0.001). No other differences were observed to be significant in the other planes of motion with the applications of support. CONCLUSIONS Based on the evidence presented, we believe that the application of cricoid pressure to a patient with a globally unstable subaxial cervical spine injury causes small displacements. There may be some benefit to the use of manual posterior cervical spine support for reducing motion at such an injured segment.