gms | German Medical Science

Fragestellung: Surgical training and biomechanical testing of fracture treatment should ideally be conducted in models that realistically represent the in vivo situation. The aim of this work was to develop and test a method for the generation of distal humerus fractures and olecranon fractures in human cadaveric specimens while preserving the soft tissue envelope.

Methodik: 21 alcohol-glycerol-fixed cadaveric upper extremity specimens (7 female, 14 male) were used for this work. The humeri were cut to a standardized length and embedded in epoxy resin. Two different experimental setups for specimen fixation and load induction were developed, one to generate distal humerus fractures and one to generate olecranon fractures. For each of the two fracture types specimens were placed in a servohydraulic material testing machine and loading was induced via the embedding in a predefined load vector direction in displacement control (100mm/sec). The force required for fracturing, the corresponding displacement and the induced energy were determined of the force-displacement graphs. After successful verification of the fracture creation with fluoroscopy qCT imaging was performed. The fractures were classified according to AO-classification and trabecular bone mineral density (BMD) in the distal radius of the specimens was measured.

Ergebnisse und Schlussfolgerung: 11 distal humerus fractures and 10 olecranon fractures could be created. Nine distal humerus fractures were classified as AO Type C and two as type B. All olecranon fractures were classified as AO type B. Distal humerus fractures required significantly more load than olecranon fractures (6077 N ±1583 vs 4136 N ±2368, p=0.038) and absorbed more energy until fracture than olecranon fractures (17.8 J ±9.1 vs 11.7 J ±7.6, p=0.11), while the displacement at fracture was similar (5.8 mm ±1.6 vs 5.9 mm ±3.1, p=0.89). For both fracture types the maximum force showed a positive correlation with the measured BMD in the distal radius (humeri r=0.92, p<0.001; olecranon r=0.70, p<0.025).

The developed and tested experimental setups are suitable for generating standardized olecranon fractures and distal humerus fractures with intact soft tissue mantle for surgical training and biomechanical testing.