title: Analysis of equivalent parameters of two spinal cord injury devices: the New York University impactor versus the Infinite Horizon impactor.
abstract: The New York University (NYU) impactor and the Infinite Horizon (IH) impactor are used to create spinal cord injury (SCI) models. However, the parameters of these two devices that yield equivalent SCI severity remain unclear.
  
  
  
  To identify equivalent parameters, rats with SCIs induced by either device set at various parameters were subjected to behavioral and histologic analyses.
  
  
  
  This is an animal laboratory study.
  
  
  
  Groups of eight rats acquired SCIs by dropping a 10 g rod from a height of 25 mm or 50 mm by using the NYU device or by delivering a force of 150 kdyn, 175 kdyn, 200 kdyn, or 250 kdyn by using the IH impactor. All injured rats were tested weekly for 8 weeks by using the Basso, Beattie, and Bresnahan (BBB) test and the ladder rung test. On the 10th week, the lesion volume of each group was measured by using a 9.4 Tesla magnetic resonance imaging (MRI), and the spinal cords were subjected to histologic analysis using anterograde biotinylated dextran amine (BDA) tracing and immunofluorescence staining with an anti-protein kinase C-gamma (PKC-γ) antibody.
  
  
  
  Basso, Beattie, and Bresnahan test scores between the 25 mm and the 200 kdyn groups as well as between the 50 mm and and 250 kdyn groups were very similar. Although it was not statistically significant, the mean scores of the ladder rung test in the 200 kdyn group were higher than the 25 mm group at all assessment time points. There was a significantly different cavity volume only between the 50 mm and the 200 kdyn groups. Midline sagittal images of the spinal cord on the MRI revealed that the 25 mm group predominantly had dorsal injuries, whereas the 200 kdyn group had deeper injuries. Anterograde tracing with BDA showed that in the 200 kdyn group, the dorsal corticospinal tract of the caudal area of the lesion was labeled. Similar labeling was not observed in the 25 mm group. Immunofluorescence staining of PKC-γ also revealed strong staining of the dorsal corticospinal tract in the 200 kdyn group but not in the 25 mm group.
  
  
  
  The 25 mm injuries generated by the NYU impactor are generally equivalent to the 200 kdyn injuries generated by using the IH impactor. However, differences in the ladder rung test scores, MRI images, BDA traces, and PKC-γ staining demonstrate that the two devices exert qualitatively different impacts on the spinal cord.
authors.affiliation: Department of Neurological Surgery, Gangneung Asan Hospital, University of Ulsan College of Medicine, Bangdong-gil, 38, Sacheon-myun, Gangneung, Republic of Korea.
authors.forename: Jin Hoon
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Republic of Korea.
authors.forename: Jeong Hoon
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Republic of Korea.
authors.forename: Sun-Kyu
authors.initials: SK
authors.lastname: Oh
authors.affiliation: Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Republic of Korea.
authors.forename: Se Rim
authors.initials: SR
authors.lastname: Baek
authors.affiliation: Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Republic of Korea.
authors.forename: Joongkee
authors.initials: J
authors.lastname: Min
authors.affiliation: Department of Computer Science and Engineering, University of Notre Dame, Notre Dame, IN 46556, USA.
authors.forename: Yong Whan
authors.initials: YW
authors.lastname: Kim
authors.affiliation: Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Republic of Korea.
authors.forename: Sang Tae
authors.initials: ST
authors.lastname: Kim
authors.affiliation: Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Republic of Korea.
authors.forename: Chul-Woong
authors.initials: CW
authors.lastname: Woo
authors.affiliation: Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Republic of Korea. Electronic address: srjeon@amc.seoul.kr.
authors.forename: Sang Ryong
authors.initials: SR
authors.lastname: Jeon
mesh_terms: D000818:Animals; D003714:Denervation / Q000295:instrumentation* / Q000379:methods; D004195:Disease Models, Animal; D005260:Female; D008279:Magnetic Resonance Imaging; D051381:Rats; D017207:Rats, Sprague-Dawley; D013119:Spinal Cord Injuries / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology; D013525:Surgical Instruments
keywords: Anterograde tracing; BBB test; IH impactor; Ladder rung test; NYU impactor; Spinal cord injury