Volume 11 Supplement 2
Junctional kyphosis: how can we detect and monitor it during growth?
© The Author(s). 2016
Published: 17 October 2016
Despite its importance in affecting adult pain, and disability, there is a lack of universal criteria for the diagnosis and evaluation of thoraco-lumbar Junctional Kyphosis (JK) and a gold standard measurement and diagnostic system does not exist.
This study aims to verify the sensibility and specificity of clinical, and Formetric surface topography (FST) data in identifying Junctional Kyphosis in respect to the radiographical standard references.
Design: This is a cross sectional study from a prospective database started in March 2003.
Participants: 38 subjects.
FST criteria: level of thoraco-lumbar inflexion point in percentage compared to the total height of the spine.
X-ray criteria: lower limit of thoracic kyphosis below T12.
Statistics: sensitivity, specificity, positive (PPV) and negative predictive values (NPV), ROC curve.
FST showed a good reliability in detecting JK: with a threshold of 75 %, PPV was 100 %, NPV was 86 % and the Area Under the Curve was 83 %.
The need for a useful criteria able to characterize JK to allow diagnosis and monitoring of the deformity is still lacking, and further studies will deepen this issue.
Despite its importance in adult life, no study has ever evaluated its prevalence and evolution in growing patients. No universal criteria have been defined to diagnose and evaluate Junctional Kyphosis (JK) and the only available gold standard is the radiographic standard reference: JK occur when the thoracic kyphosis lower limit is at L1 or below. The actual gold standard is affected by the arms position, which modifies the sagittal spine posture and possibly also alters the inflexion level (8). Therefore, the radiographic standard reference may not be considered the best possible one. A clinical tool, like the sagittal index and the rastereographic evaluations showed to be reliable and feasible in detecting and monitoring hyperkyphosis [8, 9], but no tools exist to evaluate JK.
The aim of this study was to verify the sensitivity and specificity of Formetric evaluations in identifying Junctional Kyphosis patients in respect to the radiographical reference.
Design: It is a cross sectional study, subjects came from a prospective database started in March 2003.
Participants: 22 patients provided by a Formetric evaluation at their first visit and a matchable lateral x-ray.
Comparisons: Formetric data of the group of patients with JK were compared to the formetric data of a group of 97 healthy subjects, retrieved from a screening program.
Availability of x-rays, in the frontal and lateral projection.
Both idiopathic and Scheuermann JK were included.
Formetric evaluation availability, within 1 month from the first visit.
To create a homogeneous sample, both patients and control group subjects were selected by age according to Risser score 1 . Inclusion criteria for males was age between 13 to 16; for females 12 to 14.
Scoliosis diagnosis (Cobb over 10°)
Other spine pathologies
Diagnostic tests used to detect JK
Statistics: Sensitivity, specificity, and Positive Predictive Value of each tool used to detect JK, was calculated using a 2×2 table. Positive Predictive Value was used to check the probability that in the case of a positive JK test, the patient really had the corresponding sagittal alteration. In all analyses.
p < 0.05 was considered statistically significant. Two Receiver Operating Characteristic (ROC) Curves were created to find the best threshold for both the plumbline distance and the percentage of the inflexion point.
After checking the lateral x-rays of the selected subjects, 22 had the lower limit of kyphosis below L1 and were assigned to the Junctional Kyphosis group (JK Group). 97 healthy subjects with a Formetric evaluation, who resulted negative at screening belonged to the control group.
Formetric surface topography showed a good reliability in detecting JK at the threshold of 75 %, with a Positive Predictive Value of 100 %.
This study showed that it is possible to detect JK with a Formetric evaluation, however there are some important limitations that must be taken into account to interpret the present findings. The sample size is small and it is unbalanced in respect to the control group, therefore there is the risk that the null hypothesis is confirmed by chance. However, we aimed to suggest some preliminary considerations for future analyses in larger groups of patients affected by Junctional Kyphosis.
Currently, evidence in this field is so scarce that it is difficult to compare the present results to other studies. Most of the current literature has mainly focused on how to treat thoracic hyperkyphosis and the relationship between sagittal imbalance and back pain in adulthood and old age. There is no evidence regarding how to properly identify and follow-up Junctional Kyphosis in children and adolescents through non-radiological means [11, 12].
Even if Formetric seems to be able to detect JK among healthy subjects, it is not able to distinguish each subgroup of JK and it is not able to distinguish patients with Thoracic Hyperkyphosis from patients with JK. Before performing the current study, a preliminary analysis was done, to compare subjects with thoracic hyperkyphosis, with Junctional Kyphosis subjects.
Further studies are needed to better understand this large group of spine deformities. Future development will include research studies aiming to investigate a feasible and reliable tool, to diagnose and monitor Junctional Kyphosis during growth and in the elderly, to improve the understanding of the correlations of these deformities with pain and disability. Larger sample size and a better balance between the control and the affected groups, will guarantee a higher internal and external validity.
In addition, it is now clear that there is a need for a classification system to help clinical decision making and also to estimate the correlated risks for non-treated subjects.
This study showed that it is possible to detect JK with a Formetric evaluation, but a useful criteria able to characterize JK to allow diagnosis and monitoring of the deformity is still lacking and further studies will help develop solutions for this issue.
Formetric surface topography
Positive predictive value
Negative predictive value
This article has been published as part of Scoliosis and Spinal Disorders Volume 11 Supplement 2, 2016. Research into Conservative Management of Spinal Deformities: Short Articles from the SOSORT 2015 Meeting. The full contents of the supplement are available online http://scoliosisjournal.biomedcentral.com/articles/supplements/volume-11-supplement-2.
Availability of data and materials
Data and materials are available.
AN wrote the manuscript and helped collecting and analysing data. LM collected data. JHV analysed data. SD, LM, FZ and SN helped in analysing data and revising the manuscript. All authors read and approved the final manuscript.
The authors declare that they have no competing interests, except M.D. Stefano Negrini who is one of the shareholders of ISICO Milano/Italy.
Consent for publication
Ethics approval and consent to participate
Ethical Committee of Fondazione Don Carlo Gnocchi – Lombardia approved this trial.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
- Barrey C, Roussouly P, Perrin G, Huec J-C. Sagittal balance disorders in severe degenerative spine. Can we identify the compensatory mechanisms? Eur Spine J. 2011;20(S5):626–33.View ArticlePubMedPubMed CentralGoogle Scholar
- Roussouly P, Pinheiro-Franco JL. Sagittal parameters of the spine: biomechanical approach. Eur Spine J. 2011;20(S5):578–85.View ArticlePubMedPubMed CentralGoogle Scholar
- Roussouly P, Pinheiro-Franco JL. Biomechanical analysis of the spino-pelvic organization and adaptation in pathology. Eur Spine J. 2011;20(S5):609–18.View ArticlePubMedPubMed CentralGoogle Scholar
- Schwab F, Lafage V, Patel A, Farcy J-P. Sagittal plane considerations and the pelvis in the adult patient. Spine. 2009;34(17):1828–33.View ArticlePubMedGoogle Scholar
- Schwab F, Ungar B, Blondel B, Buchowski J, Coe J, Deinlein D, et al. Scoliosis Research Society-Schwab adult spinal deformity classification: a validation study. Spine. 2012;37(12):1077–82.View ArticlePubMedGoogle Scholar
- Schwab F, Dubey A, Gamez L, El Fegoun AB, Hwang K, Pagala M, et al. Adult scoliosis: prevalence, SF-36, and nutritional parameters in an elderly volunteer population. Spine. 2005;30(9):1082–5.View ArticlePubMedGoogle Scholar
- Stagnara P. Les deformations du rachis. Paris: Masson; 1985.Google Scholar
- Zaina F, Pizzetti P, Donzelli S, Negrini F, Negrini S. Why X-rays are not reliable to assess sagittal profile: a cross sectional study. Stud Health Technol Inform. 2012;176:268–72.PubMedGoogle Scholar
- Melvin M, Mohokum M, Sylvia M, Mendoza S, Udo W, Sitter H, et al. Reproducibility of rasterstereography for kyphotic and lordotic angles, trunk length, and trunk inclination: a reliability study. Spine. 2010;35(14):1353–8.View ArticlePubMedGoogle Scholar
- Dhar S, Dangerfield PH, Dorgan JC, Klenerman L. Correlation between bone age and Risser’s sign in adolescent idiopathic scoliosis. Spine. 1993;18(1):14–9.View ArticlePubMedGoogle Scholar
- Wenger DR, Frick SL. Scheuermann kyphosis. Spine. 1999;24(24):2630–9.View ArticlePubMedGoogle Scholar
- Weiss H-R, Turnbull D, Bohr S. Brace treatment for patients with Scheuermann’s disease - a review of the literature and first experiences with a new brace design. Scoliosis. 2009;4:22.View ArticlePubMedPubMed CentralGoogle Scholar