Table 2.

Literature search of recent animal studies for spinal growth modulation

Title	Authors [reference]	Implant type	Design	Animal model (age)	Modulated growth duration (months)	Findings (coronal Cobb angle)	Other findings
Spinal growth modulation with an anterolateral flexible tether in an immature bovine model: disc health and motion preservation	Newton et al. [18]	Anterior tether	Evaluation of spinal growth modulation in a rapidly growing model	Cow (1 month)	6	37.6° Sagittal: 18.0°	Disc thickness decreased with tether. Disc wedging not observed. No evidence of disc degeneration by MRI
Spinal growth modulation with use of a tether in an immature porcine model	Newton et al. [8]	Anterior tether	Evaluation of spinal growth modulation in a model with growth similar to adolescents	Miniature pig (7 months)	6 and 12	14° after 6 months 30° after 12 months	No evidence of disc degeneration by MRI
Effects of intraoperative tensioning of an anterolateral spinal tether on spinal growth modulation in a porcine model	Newton et al. [9]	Anterior tether	Pretensioning a spinal tether at implantation tested against no tension applied	Miniature pig (7 months)	12	Pretensioning a spinal tether has no effect on ultimate deformity
Intervertebral disc health preservation after six months of spinal growth modulation	Newton et al. [10]	Anterior tether	Spinal growth modulation with tether compared to sham control	Miniature pig (7 months)	6
A porcine model for progressive thoracic scoliosis	Schwab et al. [19]	Posterior tether + ribcage ligament	Assess the 3D deformity created after tethering + concave ribcage ligament	Pig (2.7 months)	2.7	25° immediately postoperative, 55° after 2.7 months (30° progression)	Apical axial rotation increased 23°
Experimental scoliosis in an immature goat model: a method that creates idiopathic-type deformity with minimal violation of the spinal elements along the curve	Braun et al. [15]	Posterior tether	Experimental scoliosis created with posteriorly placed tether, thereafter monitored for progression	Goat (1–2 months)	1.5–3.75	Tethering immediately created a 42° curve, progressed to 60° (18° progression)
Fusionless scoliosis correction using a shape memory alloy staple in the anterior thoracic spine of the immature goat	Braun et al. [16]	Posterior tether and anterior staple	Scoliosis created over 1.5–3.75 months with tether. Tether removed, staples ± implanted to test correction	Goat (2.5–5.75 months)	1.5–3.75	Tether removal + staple corrected scoliosis 14° Tether removal corrected 7°	Partial staple backout occurred in 27 % of staples
The efficacy and integrity of shape memory alloy staples and bone anchors with ligament tethers in the fusionless treatment of experimental scoliosis	Braun et al. [12]	Anterior tether and anterior staple	Scoliosis created with a post tether (2 months), then treated with either staples or anterior tether	Goat (1.5–2 months)	3–4	Continued posterior tether: 17° progression Staples: 17° progression Anterior tether: 3.5° correction	18/42 staples loosened Clear zone noted around staples, none around bone anchors
Creation of an experimental idiopathic-type scoliosis in an immature goat model using a flexible posterior asymmetric tether	Braun et al. [20]	Posterior tether	Experimental scoliosis created with posteriorly placed tether, thereafter monitored for progression	Goat (1.5–2 months)	2	Tether immediately created a 55.4° curve; 19° progression	Deformity creation over a shorter period of time for more remaining growth available for correction
Mechanical modulation of vertebral growth in the fusionless treatment of progressive scoliosis in an experimental model	Braun et al. [21]	Posterior tether and anterior staple	Scoliosis created with a tether over 1.75–3.25 months, tether then removed and staple ± implanted	Goat (1.5–2 months)	1.75–3.25	Staples: 13.4° correction Tether removed: 7.2° correction	Increase in apical spinal segment wedging
Relative versus absolute modulation of growth in the fusionless treatment of experimental scoliosis	Braun et al. [22]	Posterior tether and anterior staple	Scoliosis created with tether over 1.75–3.25 months, tether then removed and staple ± implanted	Goat (1.5–2 months)	1.75–3.25	61° initial deformity Staples: 6.9° correction Tether removed: 1.4° correction	Concavity vertebral growth decreased 10 % in stapled goats, increased 37 % with no staple Convex vertebral growth decreased 18 % in stapled goats, increased 29 % with no staple
The effect of two clinically relevant fusionless scoliosis implant strategies on the health of the intervertebral disc: analysis in an immature goat model	Braun et al. [23]	Anterior tether and anterior staple	Scoliosis created using anterior tether or anterior staple	Goat (2 months)	6	Staple: 6.5 ± 0.9° Tether: 41.0 ± 8.3°	Both cause decreased cell density and increased cellular apoptosis No disc degenerative changes
An experimental study of correction of idiopathic-type scoliosis by staple	Zheng et al. [24]	Posterior tether plus rib resection and anterior staple	Scoliosis created with tether over 2 months, tether then removed and staple ± implanted	Goat (1.25–2 months)	2	40.8° created with tether; tether removed then 42.5° after 2 months (p > 0.05) 44.5° created with tether; tether removed + staple, then 42.5° after 2 months (p < 0.05)
Endoscopic mechanical spinal hemiepiphysiodesis modifies spine growth	Wall et al. [25]	Anterior staples	Scoliosis created using custom anterior staples	Pig (3–4 months)	2 months	Increased 21.6° Sagittal: no change	Endoscopic placement of staples was feasible