uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Spinal fractures related to ankylosing spondylitis: Epidemiology, clinical outcome and biomechanics
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.ORCID iD: 0000-0002-2724-6372
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Spinal fractures related to ankylosing spondylitis (AS) are often associated with serious complications. Therefore, knowledge of the incidence, best treatment, outcome, and prevention would assist in improving current guidelines.

Objectives: This thesis aims at (1) analysing the complications and mortality of surgical treatment, (2) mapping the incidence and treatment modalities for these patients in Sweden, as well as (3) investigating the putative preventive effect of biological disease modifying anti-rheumatic drug (bDMARD) therapy on spinal fractures related to AS.

Methods: Merged multiple national registries were used to identify predictors of mortality and spinal fractures in patients with AS. Beyond that a finite element model (FEM) was designed to simulating a cervicothoracic fracture related to AS.

Results and Conclusions: During the last two decades an increase of the incidence of vertebral fractures in patients with AS was observed. With the introduction of bDMARD treatment of AS was revolutionised and quality of life and function improved.  It seems that the improved quality of life and function in these patients does not correlate with a reduced fracture risk. Still, for the first time a beneficial effect of bDMARD with regard to spinal fracture occurrence was provided. The risk of spinal fractures was not reduced, but the debut of a spinal fracture was delayed with bDMARD. Since for this study the observation interval was only a decade, a future follow-up should revisit the effect of bDMARD on spinal fractures related to AS.

Furthermore, it was shown that posterior stabilisation is an effective method for restoring stability without the necessity of additional external fixation. Most likely the early rehabilitation reduced pulmonary complications, which in turn reduced early mortality of these fractures. The FEM could be used to identify the most appropriate implant configuration, since no well-established cadaver models exist.

Clinical Trial Registration: ClinicalTrials.gov, Identifier NCT02840695.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2017. , p. 80
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1277
Keywords [en]
ankylosing spondylitis, spinal fractures
National Category
Orthopaedics
Research subject
Orthopaedics
Identifiers
URN: urn:nbn:se:uu:diva-307373ISBN: 978-91-554-9751-4 (print)OAI: oai:DiVA.org:uu-307373DiVA, id: diva2:1046400
Public defence
2017-01-20, Gullstrandsalen, Akademiska sjukhuset, Ing 70, Uppsala, 09:00 (English)
Opponent
Supervisors
Available from: 2016-12-09 Created: 2016-11-14 Last updated: 2018-01-13
List of papers
1. Increased occurrence of spinal fractures related to ankylosing spondylitis: a prospective 22-year cohort study in 17,764 patients from a national registry in Sweden.
Open this publication in new window or tab >>Increased occurrence of spinal fractures related to ankylosing spondylitis: a prospective 22-year cohort study in 17,764 patients from a national registry in Sweden.
2013 (English)In: Patient Safety in Surgery, ISSN 1754-9493, E-ISSN 1754-9493, Vol. 7, no 2Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Ankylosing spondylitis (AS) is a rheumatoid disease leading to progressive ossification of the spinal column. Patients suffering from AS are highly susceptible to unstable vertebral fractures and often require surgical stabilisation due to long lever arms. Medical treatment of these patients improved during the last decades, but until now it is unknown whether the annual number of spinal fractures changed during the last years. Since the annual count of fracture is an effective measure for efficacy of injury prevention and patient safety in AS patients, the current recommendations of activity have to be revised accordingly.

METHODS: Data for all patients with AS treated as inpatients between 01/01/1987 and 31/12/2008 were extracted from the Swedish National Hospital Discharge Registry (SNHDR). The data in the registry are collected prospectively, recording all inpatient admissions throughout Sweden. The SNHDR uses the codes for diagnoses at discharge according to the Swedish versions of the International Classification of Diseases (ICD-9 and ICD-10).

RESULTS: During the years from 1987 to 2008 17,764 patients with AS were treated as inpatients; of these 724 patients were treated due to spinal fractures. The annual number of cervical, thoracic and lumbar fractures in the registry increased until 2008 (r = 0.94).

CONCLUSIONS: Despite the improved treatment of AS the annual number of vertebral fractures requiring inpatient care increased during the last two decades. Possible explanations are population growth, greater awareness of fractures, improved diagnostics, improved emergency care reducing fatalities, and a higher activity level of patients receiving modern medical therapy. Obviously the improvement of medical treatment did not reduce the susceptibility of these patients to unstable fractures. Thus the restrictive injury prevention recommendations for patients with AS cannot be defused, but must be critically revised to improve patient safety.

National Category
Orthopaedics
Research subject
Epidemiology
Identifiers
urn:nbn:se:uu:diva-196499 (URN)10.1186/1754-9493-7-2 (DOI)23294597 (PubMedID)
Available from: 2013-03-11 Created: 2013-03-10 Last updated: 2018-01-11Bibliographically approved
2. Complications and Survival after long Posterior Instrumentation of Cervical and Cervicothoracic Fractures related to Ankylosing Spondylitis or Diffuse Idiopathic Skeletal Hyperostosis
Open this publication in new window or tab >>Complications and Survival after long Posterior Instrumentation of Cervical and Cervicothoracic Fractures related to Ankylosing Spondylitis or Diffuse Idiopathic Skeletal Hyperostosis
2015 (English)In: Spine, ISSN 0362-2436, E-ISSN 1528-1159, Vol. 40, no 4, p. E227-E233Article in journal (Refereed) Published
Abstract [en]

STUDY DESIGN: 

Prospective cohort study.

OBJECTIVE: 

This study investigates the results of long posterior instrumentation with regard to complications and survival.

SUMMARY OF BACKGROUND DATA: 

Fractures of the cervical spine and the cervicothoracic junction related to ankylosing spinal disease (ASD) endanger both sagittal profile and spinal cord. Both anterior and posterior stabilization methods are well established, and clear treatment guidelines are missing.

METHODS: 

Forty-one consecutive patients with fractures of the cervicothoracic junction related to ASD were treated by posterior instrumentation. All patients were followed prospectively for 2 years using a standardized protocol.

RESULTS: 

Five patients experienced postoperative infections, 3 patients experienced postoperative pneumonia, 2 patients required postoperative tracheostomy, and 1 patient had postoperative cerebrospinal fluid leakage due to accidental durotomy. No patient required reoperation due to implant failure or nonunion. Mean survival was 52 months (95% confidence interval: 42-62 mo). Survival was affected by patient age, sex, smoking, and spinal cord injury.

CONCLUSION: 

Patients with ASD experiencing a fracture of the cervicothoracic region are at high risk of developing complications. The posterior instrumentation of cervical spinal fractures related to ASD is recommended due to biomechanical superiority. Level of Evidence: 4.

National Category
Orthopaedics
Research subject
Orthopaedics
Identifiers
urn:nbn:se:uu:diva-238966 (URN)10.1097/BRS.0000000000000726 (DOI)000349767500008 ()25494322 (PubMedID)
Available from: 2014-12-17 Created: 2014-12-17 Last updated: 2018-01-11Bibliographically approved
3. Surgical stabilisation improves survival of spinal fractures related to ankylosing spondylitis
Open this publication in new window or tab >>Surgical stabilisation improves survival of spinal fractures related to ankylosing spondylitis
2015 (English)In: Spine, ISSN 0362-2436, E-ISSN 1528-1159, Vol. 40, no 21, p. 1697-1702Article in journal (Refereed) Published
Abstract [en]

STUDY DESIGN: National registry cohort studyObjective. To investigate the effect of surgical stabilisation on survival of spinal fractures related to ankylosing spondylitis (AS).

SUMMARY OF BACKGROUND DATA: Spinal fractures related to AS are associated with considerable morbidity and mortality. Multiple studies suggest a beneficial effect of surgical stabilisation in these patients.

METHODS: In the Swedish patient registry all patients treated in an inpatient facility are registered with diagnosis and treatment codes. The Swedish mortality registry collects date and cause of death for all fatalities. Registry extracts of all patients with AS and spinal fractures including date of death and treatment were prepared and analysed for epidemiological purposes.

RESULTS: 17297 individual patients with AS were admitted to treatment facilities in Sweden between 1987 and 2011. 990 patients with AS (age 66±14 years) had 1131 spinal fractures, of which 534 affected cervical, 352 thoracic, and 245 lumbar vertebrae. 13% had multiple levels of injuries during the observed period. Surgically treated patients had a greater survival than those treated non-surgically (HR = 0.79, p = 0.029). Spinal cord injury was the major factor contributing to mortality in this cohort (HR = 1.55, p<0.001). The proportion of surgically treated spinal fractures increased linearly during the last decades (r = 0.92, p<0.001) and was 64% throughout the observed years.

CONCLUSIONS: Spinal cord injury threatened the survival of patients with spinal fractures related to AS. Even though surgical treatment is associated with a considerable complication rate, it improved the survival of spinal fractures related to AS.

Keywords
ankylosing spondylitis; epidemiology; incidence; mortality; national registry; spinal cord injury; spinal fracture; spinal fusion; surgical treatment; survival
National Category
Orthopaedics
Identifiers
urn:nbn:se:uu:diva-262361 (URN)10.1097/BRS.0000000000001115 (DOI)000369221200018 ()26267824 (PubMedID)
Available from: 2015-09-14 Created: 2015-09-14 Last updated: 2018-01-11Bibliographically approved
4. Biological disease-modifying anti-rheumatic treatment delayed spinal fractures related to ankylosing spondylitis: National multi-registry cohort study from the Swedish Patient Registry and the Swedish Prescribed Drugs Registry
Open this publication in new window or tab >>Biological disease-modifying anti-rheumatic treatment delayed spinal fractures related to ankylosing spondylitis: National multi-registry cohort study from the Swedish Patient Registry and the Swedish Prescribed Drugs Registry
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Objective

Ankylosing spondylitis (AS) is associated with increased spinal fracture risk due to loss of elasticity in spinal motion segments. With the introduction of biological disease modifying anti-rheumatic drugs (bDMARD) treatment for AS patients the individual course of the disease has been decelerated.  This study aims to clarify whether the improved medical therapy reduced the spinal fracture incidence.

Methods

Included were all patients with the diagnosis of AS 1987 to 2014 from the Swedish Patient Registry. From the Swedish Prescribed Drug Registry the Anatomical Therapeutic Chemical codes for bDMARD, non-steroidal anti-inflammatory drugs (NSAID), methotrexate (MTX) and sulfasalazine were extracted and numbers of prescriptions and years of treatment counted since 2005.

Results                

12297 patients with ankylosing spondylitis were included between 1987 and 2014 (age 67±19, 67% male). Of these 291 had spinal fractures between 2011 and 2014. The number of prescriptions of bDMARD increased during the last decade, but not of MTX, sulfasalazine and NSAID. 64% of all AS patients used NSAID, 13% used bDMARD, 13% used MTX, and 10% used sulfasalazine. A multivariate analysis of patients with spinal fractures 2011-2014 found bDMARD delaying spinal fracture debut by 1.24 years per year of bDMARD treatment (p=0.028). The use of bDMARD had no significant effect on spinal fracture risk (OR=0.93, 95%-C.I.=0.85-1.01, p=0.09).

Conclusion

This study failed to demonstrate a beneficial effect on spinal fracture risk for AS patients treated with bDMARD during the last decade. Still bDMARD treatment delayed spinal fracture occurrence, which is promising with regard to results from future studies.

Trial registration

ClinicalTrials.gov, Identifier NCT02840695.

National Category
Orthopaedics Rheumatology and Autoimmunity
Research subject
Orthopaedics
Identifiers
urn:nbn:se:uu:diva-307365 (URN)
Available from: 2016-11-14 Created: 2016-11-14 Last updated: 2018-01-13
5. Finite element analysis of long posterior transpedicular instrumentation for cervicothoracic fractures related to ankylosing spondylitis
Open this publication in new window or tab >>Finite element analysis of long posterior transpedicular instrumentation for cervicothoracic fractures related to ankylosing spondylitis
Show others...
2018 (English)In: Global Spine Journal, ISSN 2192-5682, E-ISSN 2192-5690, Vol. 8, no 6, p. 570-578Article in journal (Refereed) Published
Abstract [en]

Background: Spinal fractures related to AS are often treated by long posterior stabilisation. The biomechanical rationale behind is the neutralisation of long lever arms in the ankylosed spine to avoid non-union or neurological deterioration. Despite the widespread application of long posterior instrumentation it has never been investigated in a biomechanical model. The objective of this study is to develop a finite element model for spinal fractures related to AS and to establish a biomechanical foundation for long posterior stabilisation of cervicothoracic fractures related to ankylosing spondylitis (AS).

Methods: An existing finite element-model (consisting of two separately developed models) including the cervical and thoracic spine were adapted to the conditions of AS (all discs fused, C0-C1 and C1-C2 mobile) and a fracture at the level C6-C7 was simulated. Besides a normal spine (no AS, no fracture) and the uninstrumented fractured spine four different posterior transpedicular instrumentations were tested: 1. Fracture uninstrumented, 2. Short instrumentation C6-C7, 3. Medium instrumentation C5-T1, 4. Long instrumentation C3-T3, 5. Skipped level long instrumentation C3-C6-C7-T3.

Three loads (1.5g, 3.0g, 4.5g) were applied according to a specific load curve. Kinematic data such as the gap distance in the fracture site were obtained. Furthermore the stresses in the ossified parts of the discs were evaluated.

Findings: All posterior stabilisation methods could normalise the axial stability at the fracture site as measured with gap distance. With larger accelerations than 1.5g ,  it was seen that the longer instrumentations resulted in lesser maximal gap distance than the Short instrumentation. The maximum stress at the cranial instrumentation end (C3-C4) was slightly greater if every level was instrumented, than in the skipped level model. The skipped level instrumentation achieved similar rotatory stability as the long multilevel instrumentation.

Interpretation: The FE model developed simulated a spinal fracture at C6-C7 level. Skipping instrumentation levels without giving up instrumentation length also reduces the stresses in the ossified tissue within the range of the instrumentation and does not decrease the stability in a finite element model of a cervicothoracic fracture related to AS. Considering the risks associated with every additional screw placed, the skipped level instrumentation has advantages with regard to patient safety. The effects of the degree of osteoporosis, screw placement and pre-existing kyphosis on the construct stability were not investigated in this study and should be a matter of further research. 

National Category
Orthopaedics Bio Materials
Research subject
Orthopaedics
Identifiers
urn:nbn:se:uu:diva-307366 (URN)10.1177/2192568217745068 (DOI)000457230900005 ()30202710 (PubMedID)
Available from: 2016-11-14 Created: 2016-11-14 Last updated: 2019-02-18Bibliographically approved

Open Access in DiVA

fulltext(2578 kB)626 downloads
File information
File name FULLTEXT01.pdfFile size 2578 kBChecksum SHA-512
6b72188e9f0aae35246193969410f158f7674581372d4eec2d83e58013ad244a871cb8e71f03f43554b437cd5a39ff978b6a26d401e3c48d5f0f4a9b9395c1fc
Type fulltextMimetype application/pdf
Buy this publication >>

Authority records BETA

Robinson, Yohan

Search in DiVA

By author/editor
Robinson, Yohan
By organisation
Orthopaedics
Orthopaedics

Search outside of DiVA

GoogleGoogle Scholar
Total: 626 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1016 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf