Is cement-augmented sacroiliac screw fixation with partially threaded screws superior to that with fully threaded screws concerning compression and pull-out force in fragility fractures of the sacrum? - a biomechanical analysis

• Published in: BMC musculoskeletal disorders Vol. 22; no. 1; p. 1034
• Main Authors: Hack, Juliana, Safi, Maiwand, Bäumlein, Martin, Lenz, Julia, Bliemel, Christopher, Ruchholtz, Steffen, Oberkircher, Ludwig
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 10.12.2021; BioMed Central; BMC
• Subjects: Biomechanical Phenomena; Biomechanics; Bone Cements; Bone implants; Bone Screws; Cadavers; Care and treatment; Cement; Cement augmentation; Compression; Diagnosis; Fracture; Fractures; Fragility fracture of the pelvis; Fully threaded screw; Health aspects; Humans; Internal fixation in fractures; Methods; Musculoskeletal diseases; Osteoporosis; Osteosynthesis; Osteotomy; Partially threaded screw; Pelvis; Risk factors; Sacrum; Sacrum - diagnostic imaging; Sacrum - surgery; Statistical analysis; Germany; France; United States > US; Fragility fracture of the pelvis; Osteoporosis; Cement augmentation; Fully threaded screw; Partially threaded screw
• ISSN: 1471-2474; 1471-2474
• DOI: 10.1186/s12891-021-04933-y

Providing a stable osteosynthesis in fragility fractures of the pelvis can be challenging. Cement augmentation increases screw fixation in osteoporotic bone. Generating interfragmentary compression by using a lag screw also improves the stability. However, it is not known if interfragmentary compression can be achieved in osteoporotic sacral bone by cement augmentation of lag screws. The purpose of this study was to compare cement-augmented sacroiliac screw osteosynthesis using partially versus fully threaded screws in osteoporotic hemipelvises concerning compression of fracture gap and pull-out force. Nine fresh-frozen human cadaveric pelvises with osteoporosis were used. In all specimens, one side was treated with an augmented fully threaded screw (group A), and the other side with an augmented partially threaded screw (group B) after generating a vertical osteotomy on both sides of each sacrum. Afterwards, first a compression test with fracture gap measurement after tightening of the screws was performed, followed by an axial pull-out test measuring the maximum pull-out force of the screws. The fracture gap was significantly wider in group A (mean: 1.90 mm; SD: 1.64) than in group B (mean: 0.91 mm; SD: 1.03; p = 0.028). Pull-out force was higher in group A (mean: 1696 N; SD: 1452) than in group B (mean: 1616 N; SD: 824), but this difference was not statistically significant (p = 0.767). Cement augmentation of partially threaded screws in sacroiliac screw fixation allows narrowing of the fracture gap even in osteoporotic bone, while resistance against pull-out force is not significantly lower in partially threaded screws compared to fully threaded screws.