An observational study in Spinal Fusion, sponsored by AO Foundation, AO Spine. Recruiting at 17 sites in 7 countries. Open to participants aged 45 Years and older. Per ClinicalTrials.gov, last updated 2026-10-01.
Sponsored by AO Foundation, AO Spine · Observational
This is a multicenter retrospective comparative cohort study. The index surgery for this study is primary or revision long-segment posterior thoracolumbar (TL) instrumented fusion using either a supplementary rod construct or a dual-rod construct. Eligible patients who already had index surgery, will be identified for enrollment through a review of medical records of the participating surgeons at the study sites.
This multicenter retrospective comparative cohort study will enroll 1244 patients, who underwent primary or revision long-segment posterior thoracolumbar (TL) instrumented fusion using either a supplementary rod construct or a dual-rod construct. By comparing two groups of patients, ie, patients treated with supplementary rod constructs vs dual-rod constructs, in the setting of long-segment posterior instrumented spinal fusion, this study aims to provide quality evidence regarding the benefits of supplementary rod constructs in reducing the risk of RFs and other mechanical complications. This study shall provide the first long-term clinical evidence on clinical outcome and benefit of supplementary rod constructs.
All participating surgeons will be asked to identify a time point, denoted as X, when they started using predominantly either supplementary rod constructs or dual-rod constructs for long-segment posterior TL instrumented spinal fusion. This time point X must be on or before December 31, 2020 (the last eligible date for the index surgery). Participating surgeons will be instructed to select the time point X to be as early within the collection window as feasible to maximize the available FU period.
Once the time point X is identified for a participating surgeon, medical records of patients treated by this surgeon will be reviewed to identify consecutive eligible patients with the index surgery done between the time point X and December 31, 2020, inclusive. In the case that an eligible patient had undergone several surgeries during this period, the first primary or revision of long-segment posterior TL instrumented fusion using either a supplementary rod construct or a dual-rod construct is defined as the index surgery.
Patients will then be grouped based on the rod constructs into either the supplementary rod construct group or dual-rod construct group.
The study has two FU periods:
The primary study endpoint is the occurrence of the first RF within 2 years after the index surgery.
AO Foundation, AO Spine is the lead sponsor of 11 studies on the registry; 4 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Patients who underwent long-segment posterior thoracolumbar (TL) instrumented fusion
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Patients receiving long-segment posterior TL instrumented fusion using either supplementary rod constructs or dual-rod constructs (the index surgery).
If the index surgery is a revision surgery, the primary rods must be replaced in the revision surgery, with the exception of Harrington or Luque rods which can remain in place.
o If the Harrington or Luque rods remain in situ, they must already have the UIV at the thoracic level and the LIV at the sacrum/ilium, or an extension of the existing Harrington or Luque is performed such that the UIV is at the thoracic level and the LIV at the sacrum/ilium.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The index surgery for this study is the primary or revision of long-segment posterior TL instrumented fusion using dual-rod construct.
Procedure: long-segment posterior TL instrumented fusion
The index surgery for this study is the primary or revision of long-segment posterior TL instrumented fusion using either a supplementary rod construct.
Procedure: long-segment posterior TL instrumented fusion
long-segment posterior TL instrumented fusion with either supplementary rod constructs or dual-rod constructs.
Rod fracture (RF)
Incidence of rod fracture(s)
Time frame: 2 years
Time to rod fracture
Time to the first rod fracture after index surgery
Time frame: 2 years
Time to rod fracture
Time to the first rod fracture after index surgery
Time frame: 10 years and 3 months
Configurations of supplementary rod constructs
Descriptions of configurations of supplementary rod constructs
Time frame: Baseline
Treatment for rod fracture
Descriptions of different treatment strategies for rod fractures
Time frame: 10 years and 3 months
Recurrent RFs
Incidence of recurrent rod fractures
Time frame: 10 years and 3 months
Other mechanical failures
Other mechanical failures other than rod fractures
Time frame: 10 years and 3 months
Surgical complications
Selective surgical complications
Time frame: 10 years and 3 months
Not enrolling at this site.
Not enrolling at this site.
Not enrolling at this site.
Not enrolling at this site.
Plan to share: Undecided
No publications or documents are linked to this record.
Started Mar 2025 (actual). Primary completion is estimated for Dec 2027, 32 months after the start.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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AO Foundation, AO Spine