The effect of two clinically relevant fusionless scoliosis implant strategies on the health of the intervertebral disc: analysis in an immature goat model.
METHODS
Immature 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.


OBJECTIVE
Analyze the regional biochemistry and histology of spinal motion segments in healthy goat spines treated with 2 clinically relevant, fusionless scoliosis implants.


BACKGROUND
Fusionless 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.


METHODS
Scoliosis 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.


RESULTS
Neither 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.


CONCLUSIONS
Fusionless 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.
Hunt
Kenneth J
KJ
Department of Orthopaedic Surgery, University of Utah School of Medicine, Los Angeles, CA, USA.
Braun
John T
JT
Christensen
Bryt A
BA
D000367:Age Factors; D000375:Aging; D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D002470:Cell Survival; D004867:Equipment Design; D005260:Female; D006025:Glycosaminoglycans / Q000378:metabolism; D006041:Goats; D007403:Intervertebral Disc / Q000098:blood supply / Q000473:pathology / Q000601:surgery*; D055959:Intervertebral Disc Degeneration / Q000209:etiology / Q000473:pathology; D008422:Materials Testing; D023421:Models, Animal; D019637:Orthopedic Procedures / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D011859:Radiography; D012600:Scoliosis / Q000601:surgery*; D013131:Spine / Q000254:growth & development / Q000601:surgery*; D053441:Suture Anchors; D013537:Sutures; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000254:growth & development / Q000601:surgery*; D014867:Water / Q000378:metabolism
D006025:Glycosaminoglycans; D014867:Water; D053148:Caspase 3