Biomechanics of prophylactic tethering for proximal junctional kyphosis: effects of cyclic loading on tether strength and failure properties
| Autor: | Steven J. Clary, Damon E. Mar, Douglas C. Burton, Terence E. McIff, Brant Ansley, Joshua Bunch |
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| Rok vydání: | 2019 |
| Předmět: |
Adult
Male Ligamentous laxity Polyesters Kyphosis 03 medical and health sciences 0302 clinical medicine Postoperative Complications Materials Testing Cadaver Medicine Cyclic loading Humans Orthopedics and Sports Medicine Aged Aged 80 and over 030222 orthopedics business.industry Tethering Biomechanics Stiffness Middle Aged medicine.disease Biomechanical Phenomena medicine.anatomical_structure Spinal Fusion Cortical bone Stress Mechanical medicine.symptom business Cadaveric spasm 030217 neurology & neurosurgery Biomedical engineering |
| Zdroj: | Spine deformity. 8(5) |
| ISSN: | 2212-1358 |
| Popis: | Biomechanical evaluation of woven polyester tethers. To quantify changes in tether elongation, stiffness, and failure characteristics after cyclic loading. Ligamentous augmentation is gaining interest as a technique to prevent proximal junctional kyphosis (PJK) in adult spinal fusions. There are a lack of data regarding the effects of cyclic loading on polyester tether mechanical properties. Tether stretch may lead to loss of stabilization and increased risk of tether failure. Biomechanical data are needed to determine the effects of cyclic loading on tether integrity. Testing was done in two materials: (1) a synthetic cortical bone composite to determine baseline mechanical properties, and (2) nine cadaveric L1 spinous processes. 5 mm woven polyester tethers were looped through 2.5 mm holes drilled in each material. First, five tethers were tested directly to failure in the synthetic bone to establish baseline failure properties. Next, tethers were tested at one of the three cyclic load ranges [5%, 25%, and 50% (n = 5 each) of baseline failure] for 1000 cycles and then loaded to failure. Cadaveric tests were done at the 25% range and compared to synthetic bone tests at the same range. Cadaveric failure tests were classified as either tether failure or spinous process bone failure. Greater cyclic loading range had a significant effect on tether loop elongation, increased stiffness, and decreased ultimate tensile force. Among the cadaveric failure tests, 56% resulted in tether failure and the remaining 44% resulted in bone failure. Polyester tethers stretch significantly when loaded to physiological ranges. Anticipation of tether stretch may be an important consideration for a tethering strategy to prevent PJK. Improved understanding of tether material properties can provide guidance for the evaluation of clinical outcomes associated with techniques to reduce the risk of PJK caused by ligamentous laxity. Biomechanical study. |
| Databáze: | OpenAIRE |
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