title: Cement leakage causes potential thermal injury in vertebroplasty.
abstract: BACKGROUND
  Percutaneous vertebroplasty by injecting PMMA bone cement into the fractured vertebrae has been widely accepted in treatment of spinal compression fracture. However, the exothermic polymerization of bone cement may cause osseous or neural tissue injury. This study is thus designed to evaluate the potential risk of thermal damage in percutaneous vertebroplasty.
  
  
  METHODS
  Twelve porcine vertebrae were immersed in 37°C saline for the experiment. In the first stage of the study, vertebroplasty without cement leakage (control group, n = 6) was simulated. The anterior cortex, foramen, posterior cortex and the center of the vertebral body were selected for temperature measurement. Parameters including peak temperature and duration above 45°C were recorded. In the second stage, a model (n = 6) simulating bone cement leaking into the spinal canal was designed. The methods for temperature measurement were identical to those used in the first stage.
  
  
  RESULTS
  In Stage 1 of the study (vertebroplasty of the porcine vertebral body in the absence of cement leakage), the average maximal temperature at the anterior cortex was 42.4 ± 2.2°C; at the neural foramen 39.5 ± 2.1°C; at the posterior cortex 40.0 ± 2.5°C and at the vertebral center, 68.1 ± 3.4°C. The average time interval above 45°C was 0 seconds at the anterior cortex; at the neural foramen, 0 seconds; at the posterior cortex, 0 seconds and at the vertebral center, 223 seconds. Thus, except at the core of the bone cement, temperatures around the vertebral body did not exceed 45°C. In Stage 2 of the study (cement leakage model), the average maximal temperature at the anterior cortex was 42.7 ± 2.4°C; at the neural foramen, 41.1 ± 0.4°C; at the posterior cortex, 59.1 ± 7.6°C and at the vertebral center, 77.3 ± 5.7°C. The average time interval above 45°C at the anterior cortex was 0 seconds; at the neural foramen, 0 seconds; at the posterior cortex, 329.3 seconds and at the vertebral center, 393.2 seconds. Based on these results, temperatures exceeded 45°C at the posterior cortex and at the vertebral center.
  
  
  CONCLUSIONS
  The results indicated that, for bone cement confined within the vertebra, curing temperatures do not directly cause thermal injury to the nearby soft tissue. If bone cement leaks into the spinal canal, the exothermic reaction at the posterior cortex might result in thermal injury to the neural tissue.
authors: Department of Orthopaedic Surgery, Chang Gung Memorial Hospital, Chang Gung University School of Medicine, Taoyuan, Taiwan.
authors: Po-Liang
authors: PL
authors: Lai
authors: Ching-Lung
authors: CL
authors: Tai
authors: Lih-Huei
authors: LH
authors: Chen
authors: Nai-Yuan
authors: NY
authors: Nien
references: J Neurosci Methods. 1992 Dec;45(3):165-74
references: 1294851
references: Clin Orthop Relat Res. 1984 Jun;(186):284-92
references: 6723155
references: Scand J Plast Reconstr Surg. 1984;18(3):261-8
references: 6549359
references: J Biomed Mater Res B Appl Biomater. 2004 Apr 15;69(1):79-86
references: 15015214
references: Int J Pharm. 2000 Mar 20;197(1-2):161-8
references: 10704803
references: Acta Neurochir (Wien). 2008 Aug;150(8):811-5
references: 18509588
references: J Bone Joint Surg Br. 1994 Jan;76(1):155
references: 8300663
references: Spine J. 2008 May-Jun;8(3):482-7
references: 18455113
references: Bone. 1999 Aug;25(2 Suppl):17S-21S
references: 10458268
references: Clin Orthop Relat Res. 1993 Oct;(295):239-45
references: 8403655
references: Eur Spine J. 2008 Jul;17(7):982-8
references: 18446385
references: Spine (Phila Pa 1976). 2003 Jul 15;28(14):1555-9
references: 12865844
references: Spine (Phila Pa 1976). 2000 May 1;25(9):1051-2
references: 10788846
references: Orthop Clin North Am. 2009 Oct;40(4):465-71, viii
references: 19773051
references: Radiol Clin North Am. 2008 May;46(3):611-35, vii
references: 18707964
references: Spine (Phila Pa 1976). 1989 Nov;14(11):1215-9
references: 2603055
references: Radiology. 2001 Jul;220(1):213-8
references: 11426000
references: Spine (Phila Pa 1976). 2006 Jul 1;31(15):1674-8; discussion 1679
references: 16816761
references: Orthopedics. 2009 Feb;32(2):90
references: 19301801
references: Eur Spine J. 1995;4(1):15-7
references: 7749900
references: Eur Radiol. 2009 Jan;19(1):165-71
references: 18704433
references: Cardiovasc Intervent Radiol. 2008 Sep-Oct;31(5):937-47
references: 18389186