Optimizing Hybrid Plate Fixation with a Locked, Oblique End Screw in Osteoporotic Fractures.

BACKGROUND: The end screw in a fracture plate creates the greatest resistance to bending. For osteoporotic fractures treated with plates, there is some question as to the optimal screw insertion technique for the screw farthest from the fracture. A locked, oblique end screw was previously shown to increase resistance to periprosthetic fracture. It is unknown, however, how this end screw configuration would resist pullout when subjected to bending. METHODS: Narrow, low contact 3.5 mm locking compression plates with 6 and 12 holes were anchored to simulated bone material with material properties representing osteoporotic bone. Four configurations were evaluated for the end screw: perpendicular and angulated 30 degrees away from the fracture for both non-locked and locked screws (n=6 per group). The constructs were subjected to 3 point bending until the peak load and finally total construct failure was achieved. RESULTS: Peak force, stiffness, energy to peak load, and the failure mode of each construct were determined. All four 12-hole construct groups failed by gross plastic bending deformation of the plate at the fulcrum past a previously established clinically relevant limit for failure (15°). All 12-hole plate constructs failed at statistically higher loads and energy than any of the 6-hole plate constructs, with the exception of the 6-hole locked, oblique construct. CONCLUSION: The locked, oblique end screw provides equivalent pull out strength for 3.5 mm low contact plates regardless of plate length. Combined with its resistance to periprosthetic fracture, this end screw configuration appears to be the best option for the construct integrity of hybrid plating for osteoporotic fractures. CLINICAL RELEVANCE: Osteoporotic fractures are challenging to treat. The current study and the existing literature show that resistance to both bending loads and refracture at the end of a plate are minimized with a locked screw angled away from the fracture.

Temporal Variation in Ankle Fractures and Orthopedic Resident Program Planning in an Urban Level 1 Trauma Center.

Previous studies have described the mechanism of ankle fractures, their seasonal variation, and fracture patterns but never in conjunction. In addition, the cohorts previously studied were either not from trauma centers or were often dominated by low-energy mechanisms. The present study aimed to describe the epidemiology of ankle fractures presenting to an urban level 1 trauma center. The records from an urban level 1 trauma center located in the Midwestern United States were retrospectively reviewed, and the injury mechanism and energy, time of injury, day of week, month, and patient characteristics (age, gender, comorbidities, smoking status) were collected. The fractures were classified using the AO (Arbeitsgemeinschaft für Osteosynthesefragen), Lauge-Hansen, and Danis-Weber systems. Of these systems, the Lauge-Hansen classification system resulted in the greatest number of "unclassifiable" cases. Most ankle fractures were due to high-energy mechanisms, with motor vehicle collisions the most common high-energy mechanism. The review found that most ankle fractures were malleolar fractures, regardless of the mechanism of injury. The ankle fracture patients had greater rates of obesity, diabetes, and smoking than present in the region where the hospital is located. The fractures were most likely to occur in the afternoon, with more fractures presenting on the weekend than earlier in the week and more fractures in the fall and winter than in the spring and summer. The temporal variation of these fractures should be considered for health services planning, in particular, in regard to resident physician staffing at urban level 1 trauma centers.

Ankle fracture patterns in drivers are associated with femoral fracture, higher BMI, and advanced age.

OBJECTIVE: Despite advances in vehicle safety systems, motor vehicle crashes continue to cause ankle fractures. This study attempts to provide insight into the mechanisms of injury and to identify the at-risk population groups. METHODS: A study was made of ankle fractures patients treated at an urban level 1 trauma center following motor vehicle crashes, with a concurrent analysis of a nationally representative crash data set. The national data set focused on ankle fractures in drivers involved in frontal crashes. Statistical analysis was applied to the national data set to identify factors associated with fracture risk. RESULTS: Malleolar fractures occurred most frequently in the driver's right foot due to pedal interaction. The majority of complex/open fractures occurred in the left foot due to interaction with the vehicle floor. These fractures occurred in association with a femoral fracture, but their broad injury pattern suggests a range of fracture causation mechanisms. The statistical analysis indicated that the risk of fracture increased with increasing driver body mass index (BMI) and age. CONCLUSIONS: Efforts to reduce the risk of driver ankle injury should focus on right foot and pedal interaction. The range of injury patterns identified here suggest that efforts to minimize driver ankle fracture risk will likely need to consider injury tolerances for flexion, pronation/supination, and axial loading in order to capture the full range of injury mechanisms. In the clinical environment, physicians examining drivers after a frontal crash should consider those who are older or obese or who have severe femoral injury without concurrent head injury as highly suspicious for an ankle injury.