title: Biomechanical analysis of the upper thoracic spine after decompressive procedures.
abstract: BACKGROUND
  Decompressive procedures such as laminectomy, facetectomy, and costotransversectomy are routinely performed for various pathologies in the thoracic spine. The thoracic spine is unique, in part, because of the sternocostovertebral articulations that provide additional strength to the region relative to the cervical and lumbar spines. During decompressive surgeries, stability is compromised at a presently unknown point.
  
  
  OBJECTIVE
  To evaluate thoracic spinal stability after common surgical decompressive procedures in thoracic spines with intact sternocostovertebral articulations.
  
  
  METHODS
  Biomechanical cadaveric study.
  
  
  METHODS
  Fresh-frozen human cadaveric spine specimens with intact rib cages, C7-L1 (n=9), were used. An industrial robot tested all spines in axial rotation (AR), lateral bending (LB), and flexion-extension (FE) by applying pure moments (±5 Nm). The specimens were first tested in their intact state and then tested after each of the following sequential surgical decompressive procedures at T4-T5 consisting of laminectomy; unilateral facetectomy; unilateral costotransversectomy, and subsequently instrumented fusion from T3-T7.
  
  
  RESULTS
  We found that in all three planes of motion, the sequential decompressive procedures caused no statistically significant change in motion between T3-T7 or T1-T12 when compared with intact. In comparing between intact and instrumented specimens, our study found that instrumentation reduced global range of motion (ROM) between T1-T12 by 16.3% (p=.001), 12% (p=.002), and 18.4% (p=.0004) for AR, FE, and LB, respectively. Age showed a negative correlation with motion in FE (r = -0.78, p=.01) and AR (r=-0.7, p=.04).
  
  
  CONCLUSIONS
  Thoracic spine stability was not significantly affected by sequential decompressive procedures in thoracic segments at the level of the true ribs in all three planes of motion in intact thoracic specimens. Age appeared to negatively correlate with ROM of the specimen. Our study suggests that thoracic spinal stability is maintained immediately after unilateral decompression at the level of the true ribs. These preliminary observations, however, do not depict the long-term sequelae of such procedures and warrant further investigation.
authors.affiliation: Department of Neurosurgery, Neurological Institute, Cleveland Clinic, 9500 Euclid Ave, S4, Cleveland, OH 44195, USA. Electronic address: torreha@ccf.org.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Healy
authors.affiliation: Cleveland Clinic Lerner College of Medicine, 9500 Euclid Ave, NA21, Cleveland, OH 44195, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Lubelski
authors.affiliation: Head, Neck & Spine Research Laboratory, 1730 W. 25(th) St, Lutheran Hospital, 2C, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Prasath
authors.initials: P
authors.lastname: Mageswaran
authors.affiliation: Department of Neurosurgery, University of North Carolina, 170 Manning Dr, Campus Box 7060, Chapel Hill, NC 27599, USA.
authors.forename: Deb A
authors.initials: DA
authors.lastname: Bhowmick
authors.affiliation: Head, Neck & Spine Research Laboratory, 1730 W. 25(th) St, Lutheran Hospital, 2C, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Bartsch
authors.affiliation: Department of Neurosurgery, Neurological Institute, Cleveland Clinic, 9500 Euclid Ave, S4, Cleveland, OH 44195, USA.
authors.forename: Edward C
authors.initials: EC
authors.lastname: Benzel
authors.affiliation: Department of Neurosurgery, Neurological Institute, Cleveland Clinic, 9500 Euclid Ave, S4, Cleveland, OH 44195, USA.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Mroz
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena / Q000502:physiology; D019299:Decompression, Surgical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology*; D012399:Rotation; D013123:Spinal Fusion; D013904:Thoracic Vertebrae / Q000502:physiology* / Q000601:surgery
keywords: Biomechanics; Cadaver; Costotransversectomy; Decompression; Spine; Thoracic