INTRODUCTION: Vertebral deformities often occur in patients who recall no trauma, and display no evident fracture on radiographs. We hypothesise that vertebral deformity can occur by a gradual creep mechanism which is accelerated following minor damage. "Creep" is continuous deformation under constant load. MATERIALS AND METHODS: Forty-five thoracolumbar spine motion segments were tested from cadavers aged 42-92 years. Vertebral body areal BMD was measured using DXA. Specimens were compressed at 1 kN for 30 min, while creep in each vertebral body was measured using an optical MacReflex system. After 30 min recovery, each specimen was subjected to a controlled overload event which caused minor damage to one of its vertebrae. The creep test was then repeated. RESULTS: Vertebral body creep was measurable in specimens with BMD <0.5 g/cm(2). Creep was greater anteriorly than posteriorly (p < 0.001), so that vertebrae gradually developed a wedge deformity. Compressive overload reduced specimen height by 2.24 mm (STD 0.77 mm), and increased vertebral body creep by 800 % (anteriorly), 1,000 % (centrally) and 600 % (posteriorly). In 34 vertebrae with complete before-and-after data, anterior wedging occurring during the 1st creep test averaged 0.07° (STD 0.17°), and in the 2nd test (after minor damage) it averaged 0.79° (STD 1.03°). The increase was highly significant (P < 0.001). Vertebral body wedging during the 2nd creep test was proportional to the severity of damage, as quantified by specimen height loss during the overload event (r (2) = 0.51, p < 0.001, n = 34). CONCLUSIONS: Minor damage to an old vertebral body, even if it is barely discernible on radiographs, can accelerate creep to such an extent that it makes a substantial contribution to vertebral deformity.
INTRODUCTION:Vertebral deformities often occur in patients who recall no trauma, and display no evident fracture on radiographs. We hypothesise that vertebral deformity can occur by a gradual creep mechanism which is accelerated following minor damage. "Creep" is continuous deformation under constant load. MATERIALS AND METHODS: Forty-five thoracolumbar spine motion segments were tested from cadavers aged 42-92 years. Vertebral body areal BMD was measured using DXA. Specimens were compressed at 1 kN for 30 min, while creep in each vertebral body was measured using an optical MacReflex system. After 30 min recovery, each specimen was subjected to a controlled overload event which caused minor damage to one of its vertebrae. The creep test was then repeated. RESULTS: Vertebral body creep was measurable in specimens with BMD <0.5 g/cm(2). Creep was greater anteriorly than posteriorly (p < 0.001), so that vertebrae gradually developed a wedge deformity. Compressive overload reduced specimen height by 2.24 mm (STD 0.77 mm), and increased vertebral body creep by 800 % (anteriorly), 1,000 % (centrally) and 600 % (posteriorly). In 34 vertebrae with complete before-and-after data, anterior wedging occurring during the 1st creep test averaged 0.07° (STD 0.17°), and in the 2nd test (after minor damage) it averaged 0.79° (STD 1.03°). The increase was highly significant (P < 0.001). Vertebral body wedging during the 2nd creep test was proportional to the severity of damage, as quantified by specimen height loss during the overload event (r (2) = 0.51, p < 0.001, n = 34). CONCLUSIONS: Minor damage to an old vertebral body, even if it is barely discernible on radiographs, can accelerate creep to such an extent that it makes a substantial contribution to vertebral deformity.
Authors: Phillip Pollintine; Manon S L M van Tunen; Jin Luo; Matthew D Brown; Patricia Dolan; Michael A Adams Journal: Spine (Phila Pa 1976) Date: 2010-02-15 Impact factor: 3.468
Authors: Andrew M Briggs; Tim V Wrigley; Jaap H van Dieën; Bev Phillips; Sing Kai Lo; Alison M Greig; Kim L Bennell Journal: Eur Spine J Date: 2006-07-04 Impact factor: 3.134
Authors: Ekaterina Novitskaya; Carolyn Zin; Neil Chang; Esther Cory; Peter Chen; Darryl D'Lima; Robert L Sah; Joanna McKittrick Journal: Mater Sci Eng C Mater Biol Appl Date: 2014-03-30 Impact factor: 7.328
Authors: Annemarijn Weber; Stephanie M D Huysmans; Sander M J van Kuijk; Silvia M A A Evers; Elisabeth M C Jutten; Rachel Senden; Aggie T G Paulus; Joop P W van den Bergh; Rob A de Bie; Johannes M R Merk; Sandrine P G Bours; Mark Hulsbosch; Esther R C Janssen; Inez Curfs; Wouter L W van Hemert; Martijn G M Schotanus; Paul de Baat; Niek C Schepel; Willem A den Boer; Johannes G E Hendriks; Wai-Yan Liu; Marinus de Kleuver; Martin H Pouw; Miranda L van Hooff; Eva Jacobs; Paul C P H Willems Journal: BMJ Open Date: 2022-05-24 Impact factor: 3.006
Authors: Eva Jacobs; Alex K Roth; Jacobus J Arts; Lodewijk W van Rhijn; Paul C Willems Journal: J Mater Sci Mater Med Date: 2017-08-21 Impact factor: 3.896