Range of motion after thoracolumbar corpectomy: evaluation of analogous constructs with a novel low-profile anterior dual-rod system and a traditional dual-rod system
An in vitro biomechanical study.
To compare the biomechanical stability of traditional and low-profile thorocolumbar anterior instrumentation after a corpectomy with cross-connectors.
Summary of background data
Dual-rod anterior thoracolumbar lateral plates (ATLP) have been used clinically to stabilize the thorocolumbar spine.
The stability of a low-profile dual-rod system (LP DRS) and a traditional dual-rod system (DRS) was compared using a calf spine model. Two groups of seven specimens were tested intact and then in the following order: (1) ATLP with two cross-connectors and spacer; (2) ATLP with one cross-connector and spacer; (3) ATLP with spacer. Data were normalized to intact (100 %) and statistical analysis was used to determine between-group significances.
Both constructs reduced motion compared to intact in flexion–extension and lateral bending. Axial rotation motion became unstable after the corpectomy and motion was greater than intact, even with two cross-connectors with both systems. Relative to their respective intact groups, LP DRS significantly reduced motion compared to analogous DRS in flexion–extension. The addition of cross-connectors reduced motion in all loading modes.
The LP DRS provides 7.5 mm of reduced height with similar biomechanical performance. The reduced height may be beneficiary by reduced irritation and impingement on adjacent structures.
KeywordsAnterior lateral fixation Corpectomy Biomechanics Cross-connectors Low profile
The authors acknowledge funding for this project paid for by Musculoskeletal Education and Research Center (MERC), A Division of Globus Medical Inc.
Conflict of interest
M.G. received Grants from Globus Medical Inc. and Medtronic Sofamor Danek, received payment for lectures from Globus Medical Inc., Medtronic Sofamor Danek, and K2M; S.H. is a consultant, receives grants/research support, and royalties, and is on the speaker’s bureau for Globus Medical Inc; M.M, S.C, M.G, B.B, K.S, and S.K are paid employees of Globus Medical Inc.
- 4.Zhang H, Johnston CE 2nd, Pierce WA, Ashman RB, Bronson DG, Haideri NF (2006) New rod-plate anterior instrumentation for thoracolumbar/lumbar scoliosis: biomechanical evaluation compared with dual-rod and single-rod with structural interbody support. Spine (Phila Pa 1976) 31:E934–E940. doi: 10.1097/01.brs.0000247956.00599.a3 CrossRefGoogle Scholar
- 5.Bartanusz V, Muzumdar A, Hussain M, Moldavsky M, Bucklen B, Khalil S (2011) Spinal instrumentation after complete resection of the last lumbar vertebra: an in vitro biomechanical study after L5 spondylectomy. Spine (Phila Pa 1976) 36:1017–1021. doi: 10.1097/BRS.0b013e3181e92458 CrossRefGoogle Scholar
- 10.Chou D, Larios AE, Chamberlain RH, Fifield MS, Hartl R, Dickman CA, Sonntag VK, Crawford NR (2006) A biomechanical comparison of three anterior thoracolumbar implants after corpectomy: are two screws better than one? J Neurosurg Spine 4:213–218. doi: 10.3171/spi.2006.4.3.213 CrossRefPubMedGoogle Scholar