Author and Year | Objective | Cohort | Age and Sex | Follow-Up | Results | Supports IVD & Bony Stress Associative Relationship | Limitations & Bias |
Hollenberg et al. (2002)(16) | To examine the reliability of MRI grading system of bony stress in pars interarticularis | 55 athletes with LBP and suspected stress injury to pars interarticularis | Female age 14.7 ± 2.6 (8–22 years); male age 18.9 ± 4.5 (14–31 years). 28 females and 27 males | Retrospective study | 23 of 55 patients had bony stress or spondylolysis visible on MRI. Interobserver reliability for the three radiologists was sufficient (Kappa coefficients ranged from 0.71 to 1.00 (95% CI, 0.55–0.86)) | N/A | N/A |
Congeni et al. (1997)(17) | To investigate the treatment regimen and radiological healing of bony stress and fracture | 40 athletes with LBP and evidence of spondylolysis by nuclear medicine study | Average age of 14.5 years (range 12–20); 31 males and nine females | Prospective study, follow-up of 6 months | Hyperextension avoidance for 6–8 weeks, physical therapy and guided return to play sport was useful in 47% of acute fractures | N/A | N/A |
Maurer et al. (2011)(18) | To compare MRI findings between rowers and inactive controls | 22 asymptomatic rowers and 22 controls | Rowers' age 16.0 ± 1.63 years, controls' age 16.27 ± 1.31 years. 44 males | Cross sectional study | Seven rowers had IVD degeneration and six had bony stress; three controls had IVD degeneration and none had bony stress | Yes | Small cohort size, a specific patient group - findings may be less relevant to a broader population |
Ranson et al. (2010)(19) | To study changes in MRI of lumbar spine and incidence of stress fracture captured over two years | 28 fast bowlers | Average age of 19 years (range 16–24); 28 males | Prospective study; follow-up of two years | Twelve bowlers had stress fractures. Fifteen bowlers had bony stress; 11 of these had a partial or complete stress fracture within a mean of 10 weeks; the relationship was highly significant Fisher's exact text, p < 0.001). Three bowlers had IVD degeneration | Yes | Small cohort size, a specific patient group - findings may be less relevant to a broader population |
Sharma et al. (2014)(6) | To investigate the prevalence and pattern of IVD degeneration in lumbar segments with and without bony stress | 87 patients under 25 years diagnosed with bony stress or stress fracture | Average age of 15.3 ± 3.3 (range 5–25); 55 males and 32 females | Retrospective study | Burden (per disc basis, e.g. if AF tear in 1 of 2 stressed IVDs, burden is 0.5) of AF tears 0.6 in stressed IVDs compared to 0.28 in controls. NP degeneration burden was 0.13 in stressed IVDs and 0.02 in control IVDs | Yes | Specific patient group - findings may be less relevant to a broader population |
Sharma et al. (2017)(7) | To study the pattern of IVD degeneration in lumbar segments with and without bony stress | 42 patients under 25 years diagnosed with bony stress or stress fracture and presenting with LBP without acute injury | Average age of 16.0 ± 3.7 (range 7–25 years); 22 males and 20 females | Retrospective study; follow-up of > 6 months | Burden (per disc basis, e.g. if AF tear in 1 of 2 stressed IVDs, burden is 0.5) of AF fissures, radial fissures and herniation was more in bony stress segments compared to the control segments (0.76 ± 0.35, 0.59 ± 0.43, 0.07 ± 0.20, compared to 0.37 ± 0.48, 0.17 ± 0.38, 0.00 ± 0.00 respectively) | Yes | Specific patient group - findings may be less relevant to a broader population |
Celticki et al. (2018) (20) | To investigate the prevalence of spondylolysis and IVD degeneration in different types of military roles and payload weights | 642 military personnel with LBP; CT or MRI scans available | Average age of 22.9 years; 642 males | Retrospective study | 14.6% had spondylolysis; higher prevalence of spondylolysis (34.2%) in the group with increased payload (increased axial load on the spine); 27.2% of spondylolysis had disc degeneration, 72.7% did not | N/A | follow up scans not available, did not provide results of IVD degeneration in non-spondylolytic group |
Chepurin et al. (2019) (21) | To investigate the prevalence of bony stress and IVD degeneration | 55 patients with bony stress; 75 patients without bony stress on MRI | Average age 18.2 years; 73 males and 57 females | Retrospective study | Bony stress segments had over twofold (odds ratio 2.3 (95%CI 1.1–4.8)) higher likelihood of having IVD degeneration than the normal segments | Yes | Specific patient group - findings may be less relevant to a wider audience |
Finite Element Modelling Studies |
Author and Year | Objective | Model Characteristics | Segment Tested | Load | Results | Supports IVD and Bony Stress Associative Relationship | Limitations and Bias |
Kim et al. (2013)(22) | To study the biomechanical influence of facet orientation and facet tropism on stress in the corresponding segment | CT data from a 46-year-old male | L2-3 | Flexion, extension, lateral bending, torsion, anterior shear | Facet orientation did not alter IVD stress or facet joint stress at the corresponding level | N/A | Viscoelastic property of IVD tissues not considered |
Qasim et al. (2014)(23) | To investigate the initiation and progression of structural damage in the annulus based on continuum damage mechanics methodology | Modelling IVD degeneration to mimic Thompson Grade III and IV degenerative changes, fatigue analyses based on damage accumulation | L4-5 | Flexion, extension, axial rotation, lateral bending | Increased stress in posterior AF and central EP in disc degenerated model when compared to the healthy model | Yes | Viscoelastic property of IVD tissues not considered. Changes in viscoelastic properties due to fluid flow not considered in fatigue analysis |
Guo et al. (2017)(24) | To investigate the effect of single-level disc degeneration on the dynamic response of whole lumbar spine to vibration | CT data from female spine, motion segment with IVD degeneration at L4-5 | L1-S1 | Follower compressive (400N) with vibrations (± 40N) | Decreased IVD bulge and AF stress and increased NP stress in IVD degeneration model compared with the intact model | N/A | A simplistic model of IVD degeneration based on 16.5% and 33% disc height loss and change in material properties |
Du et al. (2014)(25) | To investigate how sitting posture affects the response of thoracolumbar spine in ejection systems | Dynamic multi-body model, and an FE model of spine based on a 35 years old healthy male | T9-S1 | Axial compressive | Ejection impact contributed to axial compression and anterior flexion of the spine, more so in the relaxed posture than the normal sitting posture | Yes | Viscoelastic property of tissues not considered |
Huang et al. (2014)(26) | To investigate the influence of NP removal on biomechanical response of lumbar motion segment | CT data from an adult male | L4-5 | Axial compressive, flexion, extension, lateral bending, axial rotation | Increased stress in AF and facet joints | Yes | Complete NP removal not a clinically relevant scenario, single segment model – did not study adjacent segment changes |
Galbusera et al. (2011)(27) | To study the effects of degenerative morphological changes in IVD on lumbar spine biomechanics | CT based poroelastic model | L4-5 | Axial compressive, flexion and extension | Axial displacement, facet force decreased when IVD height is decreased. Axial displacement, facet force and fluid loss reduced when water content is decreased. EP sclerosis had no significant findings. | No | Artificial IVD height, EP sclerosis, water content and IVD permeability model not comprehensively validated, sclerosis modelling approach arbitrary |
Chosa et al. (2004)(28) | To evaluate stress in the lumbar pars interarticularis region | CT data from a 29-year-old male | L4-5 | Axial compressive, flexion, extension, lateral bending, rotation | Stress located principally in pars interarticularis. Axial compression caused stress in whole vertebra, compression and flexion caused stress in anterior vertebra and posterior pars, compression and extension caused stress in posterior vertebra and pars, compression and right lateral bending caused stress in right vertebra and pars, compression and left rotation caused stress in whole vertebra and pars | Yes | Viscoelastic property of IVD tissues not considered; single motion segment modelled, |
Yu et al. (2015)(29) | To compare stress distribution between normal and degenerated IVD models | CT model, one segment with IVD degeneration | L4-5 | Axial compressive, flexion, extension, lateral bending, axial rotation | Similar stress distribution between normal and IVD degenerated segment. Stress increased most under flexion loads | No | IVD degeneration artificial, viscoelastic property of IVD tissues not considered, lack of model validation |
Zahari et al. (2017)(30) | To study the effects of body weight on intradiscal pressure and AF stress | CT data from a 21-year-old male, no deformities | L1-5 | Axial compressive, flexion, extension | Maximum Iintradiscal pressure at L12 in flexion, but the greatest increase in pressure with weight observed at L45 (~ 30%). Intradiscal pressure decreased with increasing weight in extension loading | Yes | Viscoelastic property of IVD tissues not considered; lack of model validation |
In-vivo Biomechanical Testing Studies |
Author and Year | Objective | Cohort | Intervention | Follow-Up | Results | Supports IVD and Bony Stress Associative Relationship | Limitations and Bias |
Sairyo et al. (2004)(31) | To understand the pathomechanism of slippage in immature spines | 20 Wistar rats | L5 laminectomy, and L56 bilateral facetectomy | One, three, five, seven days | None had IVD degeneration; slippage observed on Day seven, growth plate injury of the vertebral body | N/A | Spinal loading and anatomy different in rats compared with humans; IVD degeneration may have a more extended gestation period |
Baranto et al. (2005)(32) | To study injury patterns in the adolescent porcine spines with induced IVD degeneration | 24 pigs | Hole drilled through cranial EP; animals sacrificed two months later functional spinal units harvested and exposed to compression load until failure | Two months | IVD degenerated segments were able to tolerate more compressive load compared with the non-degenerated ones | No | Method to induce IVD degeneration is not directly relevant to naturally occurring degeneration in humans. |
Kim et al. (2012)(33) | To investigate if the sustained application of shear force causes IVD degeneration | 15 male Sprague–Dawley rats | Implantable loading device creating a shear force | One, two weeks | All 12 shear loaded rats had IVD degeneration, 0 in the control group | N/A | Artificially induced shear stress may be different in magnitude, application, duration from naturally occurring shear stress in human IVDs |
In-vitro Biomechanical Testing Studies |
Author and Year | Objective | Sample Size | Sex | Load | Results | Supports IVD and Bony Stress Associative Relationship | Limitations and Bias |
Ryan et al. (2008)(34) | To understand the interdependence of IVD and subdiscal trabecular bone properties. | Lumbar spine segments from 10 sacrificed pigs | Complex axial loading of segments | N/A | Compressive load resulted in uniform stress distribution in the IVD. Asymmetric load resulted in increased peripheral IVD and adjacent bone stress | Yes | Anatomical differences between pigs and human spines, and therefore results not directly translatable |
Veres et al. (2010)(35) | To investigate whether torsion in combination with flexion affects the failure mechanics of IVD | 30 motion segments from ten sacrificed sheep | Axial rotation and flexion | N/A | In 25 motion segments, 17 vertebral failure and eight IVD failure; IVD failure mostly occurring in mature motion segments | Yes | Morphological and Stiffness characteristics different between ovine and human discs |
Wade et al. (2014)(36) | To study IVD herniation under compression and flexion | 72 motion segments from sheep | Axial compressive load and flexion | N/A | IVD failure required 18% less force than vertebral fracture | N/A | Morphological and Stiffness characteristics different between ovine and human discs |
Berger-Roscher et al. (2017)(37) | To investigate how loading combinations influence IVD failure | 30 lumbar spinal segments from nine sacrificed sheep | Combination of axial compressive, bending and torsion loads, 1000 cycles at 2 Hz loading of segments | N/A | 13 segments experienced large endplate failures, four experienced sole annulus failures | Yes | Morphological and Stiffness characteristics different between ovine and human discs |
Sapiee et al. (2019) (38) | To investigate the risk of IVD failure due to increased sacral slope and shear stresses | 35 ovine lumbar spinal segments | Axial compressive load (nine in the horizontal position, 26 in slopping posture) | N/A | All nine horizontal segments had endplate failure, none had pars fracture. Of 26 slopping, nine had pars fracture observed with or directly after IVD failure | Yes | Morphological and Stiffness characteristics different between ovine and human discs |
Hansson et al. (1987)(39) | To study the effect of cyclic loading on IVD degeneration and failure types | 17 thoracolumbar segments | N/A | Cyclic axial compressive | Eight normal, two slightly degenerated, seven moderately degenerated, zero severely degenerated | Yes | Small sample size, bending and torsional loads not employed |
Hansson et al. (1987)(40) | To compare the degree of IVD degeneration with compressive strengths of underlying trabecular bone | 12 lumbar spinal segments | N/A | Cyclic axial compressive | Trabecular bone specimens from slightly degenerated IVDs were 24% stronger and 16% stiffer than those from severely degenerated IVDs | Yes | All samples were obtained from only three human spines. |
Miller et al. (1988)(41) | To correlate IVD degeneration with age, sex, and spinal level | 600 lumbar IVDs from 273 cadavers | 363 males and 237 females | N/A | Male discs more degenerated than female discs at all ages. By age 50, 97% of IVDs exhibited degeneration. L3-4 and L4-5 are usually most degenerated | N/A | N/A |
Duncan et al. (1991)(14) | To understand the relevance of axial rotation in IVD degeneration and facet asymmetry in injury mechanisms | 35 L23 and 35 L45 specimens | 25 males and 10 females | Cyclic axial torsion | No significant effect from different facet joints on the motion of segment or IVD degeneration | No | N/A |
Kasra et al. (1992)(42) | Experimental and finite element modelling study to measure the impact of vibration on spinal discs and vertebrae | One T12-L1 and six lumbar motion segments | Spinal segments were extracted from four males and two females | Cyclic axial compression | Fracture of bone adjacent to NP was most common and associated with IVD degeneration, AF not vulnerable to rupture under pure axial vibrations | Yes | Small sample size |
Adams et al. (1993)(43) | To investigate abnormal IVD stress concentration after vertebral body damage | 23 lumbar motion segments | 17 males and six females | Constant axial compression | Testing in the damage induced samples, stress levels in NP and anterior AF fell 30%, while stress increased in posterior AF. | Yes | Only four samples < 25 years of age, response to torsional and bending loads not examined |
Adams et al. (2000)(44) | To investigate if minor damage to vertebral bodies can lead to progressive IVD disruption | 38 lumbar motion segments | N/A | Compression and Bending | EP damage caused 25% (± 27% )reduction in NP pressure and 16%(± 49%) increased pressure in posterior AF. | Yes | Torsional loads not examined, cyclic loading of the ligamentous lumbar spine gives unreliable results beyond 2000 cycles (45) |