• Kenneth J Hunt, John T Braun, and Bryt A Christensen.
• Department of Orthopaedic Surgery, University of Utah School of Medicine, Los Angeles, CA, USA.
• Spine. 2010 Feb 15; 35 (4): 371-7.

Study DesignImmature goat spines were instrumented at 5 levels with 2 different fusionless scoliosis implants. Instrumented and subadjacent spinal segments were analyzed to determine the effect on the disc and endplate.ObjectiveAnalyze the regional biochemistry and histology of spinal motion segments in healthy goat spines treated with 2 clinically relevant, fusionless scoliosis implants.Summary Of Background DataFusionless scoliosis surgery is thought to be more physiologic than fusion as it preserves the growth, motion, and function of the spine. There are presently little data supporting this belief.MethodsScoliosis was created in twelve 8-week-old female goats (n = 6 per group) using 1 of 2 fusionless scoliosis implant strategies: 2 SMA staples per level or a bone anchor/ligament tether. A third group served as controls (n = 6). Goats were analyzed after 6 months. Qualitative and quantitative analyses were performed on spinal motion segments using H&E, TUNEL, and caspase-3 staining.ResultsNeither implant strategy produced degenerative changes in the disc. However, discs at instrumented levels in both groups demonstrated decreased cell density (P < 0.01) and increased cellular apoptosis (P < 0.001) compared to controls. Subadjacent discs demonstrated preservation of viable cells and endplate vascularity compared to instrumented discs.ConclusionFusionless scoliosis implants result in alterations in viable cell density within the disc and reduced vascularity in the vertebral endplates of instrumented but not subadjacent discs. Though obvious disc degeneration was not observed, the implications of the cellular and histologic changes are not known. Additional study will be necessary to better understand various fusionless scoliosis surgery strategies and their effect on surrounding tissues.

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