Adjacent Segment DiseaseSTASSNCT07661199
Surgical Treatment of Adjacent Segment Stenosis
A study testing Microsurgical Decompression with Extension of Fusion and Microsurgical Decompression Alone in people with Adjacent Segment Disease and Lumbar Spinal Stenosis, run by Charite University, Berlin, Germany at 1 site in Germany.
Trial summary
The goal of this clinical trial is to learn whether microdecompression alone is as effective as decompression with extension of fusion surgery in patients with symptomatic adjacent segment stenosis after previous lumbar fusion surgery. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Adjacent Segment Disease, Lumbar Spinal Stenosis
- What is being tested?
- Microsurgical Decompression with Extension of Fusion and Microsurgical Decompression Alone
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 338 participants
- Where
- 1 siteGermany
- Study dates
- 27 Oct 2026to 1 Mar 2031
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Age ≥18 years.
- Oswestry Disability Index (ODI) between 30% and 80% at screening.
- Symptomatic adjacent segment stenosis following degenerative lumbar fusion surgery.
- Persistent symptoms despite at least 6 weeks of appropriate conservative treatment.
- Radiological evidence of adjacent segment spinal stenosis on magnetic resonance imaging (MRI).
- Ability to understand the study procedures and complete patient-reported outcome questionnaires.
- Ability to provide written informed consent.
Who cannot join
- Adjacent segment kyphosis or scoliosis greater than 10 degrees.
- Screw loosening or pseudarthrosis of the previous fusion construct.
- Known current pregnancy or breastfeeding.
- Acute traumatic spinal injury or fracture.
- Active inflammatory disease of the spine.
- Active neoplastic disease of the spine.
Show all 12Show fewer
- Contraindication to spinal surgery.
- Inability to provide informed consent or complete study questionnaires.
- Symptoms attributable to spinal stenosis are not the predominant clinical complaint
- Foraminal stenosis grade ≥2 according to the Lee classification.
- Dynamic spondylolisthesis ≥3 mm on flexion-extension radiographs.
- Persons involuntarily detained by judicial or administrative order.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Germany1 site, 1 recruiting
- Recruiting
Charité - Universitätsmedizin Berlin
Berlin, State of Berlin, 10117
Anton Früh, PD MD M.Sc., +49939459669376, anton.frueh@charite.de
About this study
The goal of this clinical trial is to learn whether microdecompression alone is as effective as decompression with extension of fusion surgery in patients with symptomatic adjacent segment stenosis after previous lumbar fusion surgery.
The main questions it aims to answer are:
Read more
Is microdecompression alone non-inferior to decompression with extension of fusion in improving disability 24 months after surgery, as measured by the Oswestry Disability Index (ODI)? Does microdecompression alone result in similar or lower rates of complications, reoperations, pain, and radiological progression compared with decompression and fusion?
Researchers will compare microdecompression alone to decompression with extension of lumbar fusion to determine whether the less invasive procedure can achieve similar clinical outcomes while reducing surgical burden and preserving spinal structures.
Participants will:
Be randomly assigned to one of two treatment groups: microdecompression alone or decompression with extension of lumbar fusion.
Undergo the assigned surgical treatment. Attend clinical and radiological follow-up visits at 6, 12, and 24 months after surgery.
Complete questionnaires assessing disability, pain, quality of life, sleep quality, and mental health.
Undergo routine imaging and clinical examinations to evaluate treatment outcomes and possible complications.
- Conditions
- Adjacent Segment Disease, Lumbar Spinal Stenosis
- Being tested
- Microsurgical Decompression with Extension of Fusion, Microsurgical Decompression Alone
- Keywords
- Adjacent Segment Disease, Adjacent Segment Stenosis, Lumbar Spinal Stenosis
- Medical subject headings
- Spinal Stenosis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Microsurgical Decompression with Extension of FusionProcedure or surgery
Participants undergo microsurgical decompression of symptomatic adjacent segment stenosis combined with extension of the existing lumbar fusion.
Microsurgical Decompression AloneProcedure or surgery
Participants undergo microsurgical decompression of symptomatic adjacent segment stenosis after previous lumbar fusion surgery without extension of the existing fusion.
| Study group | Role | What they receive |
|---|---|---|
| Control | Active comparator | Decompression and fusion Receives: Procedure: Microsurgical Decompression with Extension of Fusion |
| Intervention | Active comparator | Mircosurgical decompression only Receives: Procedure: Microsurgical Decompression Alone |
What is being measured
The primary outcome is the main question the study is designed to answer.
Proportion of Participants Achieving at Least 30% Reduction in Oswestry Disability Index (ODI)
The primary endpoint is the proportion of participants achieving a reduction of at least 30% in the Oswestry Disability Index (ODI) compared with baseline. The ODI is a validated patient-reported outcome measure assessing disability related to lumbar spine disorders on a scale from 0% to 100%. A reduction of at least 30% is considered clinically meaningful.
Measured: 24 months after surgery
Secondary outcomes (20)
Pain related disability
Disability related to low back pain assessed using the Oswestry Disability Index (ODI). The ODI score ranges from 0 to 100%, with higher scores indicating greater disability and worse functional impairment.
Measured: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Leg Pain Intensity at Rest
Pain intensity assessed using the Numeric Rating Scale (NRS; 0-10) for leg pain at rest.The NRS ranges from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate greater pain intensity.
Measured: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Leg Pain Intensity during Movement
Pain intensity assessed using the Numeric Rating Scale (NRS; 0-10) for leg pain during movement.The NRS ranges from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate greater pain intensity.
Measured: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Back Pain Intensity at Rest
Pain intensity assessed using the Numeric Rating Scale (NRS; 0-10) for back pain at rest.The NRS ranges from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate greater pain intensity.
Measured: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Back Pain Intensity during Movement
Pain intensity assessed using the Numeric Rating Scale (NRS; 0-10) for back pain during movement.The NRS ranges from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate greater pain intensity.
Measured: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Maximum Walking Distance
Maximum walking distance measured in meters.
Measured: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Health-Related Quality of Life Assessed by the 36-Item Short Form Health Survey (SF-36)
generates eight domain scores (physical functioning, role limitations due to physical health, bodily pain, general health perceptions, vitality, social functioning, role limitations due to emotional problems, and mental health), each transformed to a scale ranging from 0 to 100, with higher scores indicating better health-related quality of life and functional status. Unit of Measure: Points on a scale (0-100).
Measured: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Health-Related Quality of Life Assessed by the EuroQol 5-Dimension 5-Level Questionnaire (EQ-5D-5L) Index Score
Health-related quality of life assessed using the EuroQol 5-Dimension 5-Level questionnaire (EQ-5D-5L). The EQ-5D-5L evaluates five dimensions of health status (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression), each with five response levels. Responses are converted into a single EQ-5D-5L Index Score using an established country-specific value set. Higher index scores indicate better health-related quality of life. Unit of Measure: Utility index score (higher scores indicate better health-related quality of life).
Measured: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Mood Assessed by the German General Depression Scale - Short Form (ADS-K)
Depressive symptoms assessed using the German General Depression Scale - Short Form (ADS-K). The ADS-K is a self-report questionnaire comprising 15 items, each rated on a 4-point Likert scale (0-3 points). Total scores range from 0 to 45 points, with higher scores indicating more severe depressive symptomatology and worse mood status. Unit of Measure: Points on a scale (range: 0-45; higher scores indicate more severe depressive symptoms)
Measured: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Sleep Quality Assessed by the Pittsburgh Sleep Quality Index (PSQI)
Sleep quality assessed using the Pittsburgh Sleep Quality Index (PSQI). The PSQI is a self-administered questionnaire evaluating sleep quality and disturbances over the previous month across seven domains: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. Component scores are summed to generate a global PSQI score ranging from 0 to 21 points, with higher scores indicating poorer sleep quality and greater sleep disturbance. Unit of Measure: Points on a scale (range: 0-21; higher scores indicate worse sleep quality).
Measured: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Length of hospital stay
Length of hospital stay measured in days from surgery until hospital discharge.
Measured: From date of surgery until hospital discharge, up to 30 days postoperatively
Intensive Care Unit Stay
Duration of intensive care unit stay measured in days.
Measured: From admission to the intensive care unit after surgery until discharge from the intensive care unit, up to 30 days postoperatively.
Additional or Revision Spine Surgery
Proportion of participants requiring additional spinal surgery or revision surgery during follow-up.
Measured: Up to 24 months after surgery
Perioperative Complications
Number and type of perioperative complications associated with the surgical procedure.
Measured: Perioperative/Periprocedural
Operative Parameters
Operative duration, intraoperative blood loss
Measured: Perioperative/Periprocedural
Dynamic Spondylolisthesis
Presence of dynamic spondylolisthesis defined as a translation of ≥3 mm on flexion-extension radiographs.Unit of Measure: Participants with dynamic spondylolisthesis.
Measured: 24 month after surgery
Central Stenosis Severity Assessed by the Schizas Classification
Central canal stenosis at the adjacent segment assessed on MRI using the Schizas classification (Grades A-D).Unit of Measure: Grade (A-D; higher grades indicate more severe stenosis).
Measured: 24 months after surgery
Foraminal Stenosis Severity Assessed by the Lee Classification
Foraminal stenosis at the adjacent segment assessed on MRI using the Lee classification (Grades 1-4).Unit of Measure: Grade (1-4; higher grades indicate more severe foraminal stenosis).
Measured: 24 months after surgery.
Implant Integrity
Implant integrity assessed on radiographs, including evidence of implant loosening, breakage, or material dislocation.Unit of Measure: Participants with implant failure.
Measured: 24 months after surgery.
Segmental Lordosis
Segmental lordosis measured on standing lateral radiographs.Unit of Measure: Degrees (°).
Measured: 24 months after surgery.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Jun 2026
- Study start27 Oct 2026
- Primary completion30 Sep 2030 (estimated)
- Study completion1 Mar 2031 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Adjacent Segment DiseaseStudies of the same condition, open and under way.
- More trials run by Charite University, Berlin, GermanyThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 338 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Charite University, Berlin, Germany
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Anton Früh, Charite University, Berlin, Germany
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07661199
- Sponsor's protocol ID
- STASS-Trial
- Other IDs
- 574896382
- Acronym
- STASS
- Status last verified
- Oct 2026
- First submitted
- 29 May 2026
- Last updated
- 28 Oct 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Individual participant data underlying the results reported in publications arising from this study, after de-identification, will be made available upon reasonable request to the corresponding investigator. Supporting documents including the study protocol, statistical analysis plan, and data dictionary will also be made available.
Study at a glance
From the registry record, last updated by the sponsor on 28 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Surgical Treatment of Adjacent Segment Stenosis
- ClinicalTrials.gov ID
- NCT07661199
- Acronym / sponsor ID
- STASS / STASS-Trial
- Conditions
- Adjacent Segment Disease, Lumbar Spinal Stenosis
- Keywords
- Adjacent Segment Disease, Adjacent Segment Stenosis, Lumbar Spinal Stenosis
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 338 participants (estimated)
- Lead sponsor
- Charite University, Berlin, GermanyUniversity, hospital or other
- Study start
- 27 Oct 2026 (actual)
- Primary completion
- 30 Sep 2030 (estimated)
- Study completion
- 1 Mar 2031 (estimated)
- First posted
- 22 Jun 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this clinical trial is to learn whether microdecompression alone is as effective as decompression with extension of fusion surgery in patients with symptomatic adjacent segment stenosis after previous lumbar fusion surgery.
The main questions it aims to answer are:
Is microdecompression alone non-inferior to decompression with extension of fusion in improving disability 24 months after surgery, as measured by the Oswestry Disability Index (ODI)? Does microdecompression alone result in similar or lower rates of complications, reoperations, pain, and radiological progression compared with decompression and fusion?
Researchers will compare microdecompression alone to decompression with extension of lumbar fusion to determine whether the less invasive procedure can achieve similar clinical outcomes while reducing surgical burden and preserving spinal structures.
Participants will:
Be randomly assigned to one of two treatment groups: microdecompression alone or decompression with extension of lumbar fusion.
Undergo the assigned surgical treatment. Attend clinical and radiological follow-up visits at 6, 12, and 24 months after surgery.
Complete questionnaires assessing disability, pain, quality of life, sleep quality, and mental health.
Undergo routine imaging and clinical examinations to evaluate treatment outcomes and possible complications.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Control | Active comparator | Procedure: Microsurgical Decompression with Extension of FusionDecompression and fusion |
| Intervention | Active comparator | Procedure: Microsurgical Decompression AloneMircosurgical decompression only |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (7 listed)
- Age ≥18 years.
- Oswestry Disability Index (ODI) between 30% and 80% at screening.
- Symptomatic adjacent segment stenosis following degenerative lumbar fusion surgery.
- Persistent symptoms despite at least 6 weeks of appropriate conservative treatment.
- Radiological evidence of adjacent segment spinal stenosis on magnetic resonance imaging (MRI).
Key exclusion criteria (12 listed)
- Adjacent segment kyphosis or scoliosis greater than 10 degrees.
- Screw loosening or pseudarthrosis of the previous fusion construct.
- Known current pregnancy or breastfeeding.
- Acute traumatic spinal injury or fracture.
- Active inflammatory disease of the spine.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Microsurgical Decompression with Extension of FusionParticipants undergo microsurgical decompression of symptomatic adjacent segment stenosis combined with extension of the existing lumbar fusion. | Procedure or surgery | Control |
| Microsurgical Decompression AloneParticipants undergo microsurgical decompression of symptomatic adjacent segment stenosis after previous lumbar fusion surgery without extension of the existing fusion. | Procedure or surgery | Intervention |
Primary outcome
Proportion of Participants Achieving at Least 30% Reduction in Oswestry Disability Index (ODI)
Time frame: 24 months after surgery
The primary endpoint is the proportion of participants achieving a reduction of at least 30% in the Oswestry Disability Index (ODI) compared with baseline. The ODI is a validated patient-reported outcome measure assessing disability related to lumbar spine disorders on a scale from 0% to 100%. A reduction of at least 30% is considered clinically meaningful.
20 secondary outcomes
Pain related disability
Time frame: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Leg Pain Intensity at Rest
Time frame: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Leg Pain Intensity during Movement
Time frame: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Back Pain Intensity at Rest
Time frame: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Back Pain Intensity during Movement
Time frame: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Maximum Walking Distance
Time frame: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Health-Related Quality of Life Assessed by the 36-Item Short Form Health Survey (SF-36)
Time frame: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Health-Related Quality of Life Assessed by the EuroQol 5-Dimension 5-Level Questionnaire (EQ-5D-5L) Index Score
Time frame: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Mood Assessed by the German General Depression Scale - Short Form (ADS-K)
Time frame: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Sleep Quality Assessed by the Pittsburgh Sleep Quality Index (PSQI)
Time frame: Baseline (before surgery), 6 months after surgery, 12 months after surgery, and 24 months after surgery.
Length of hospital stay
Time frame: From date of surgery until hospital discharge, up to 30 days postoperatively
Intensive Care Unit Stay
Time frame: From admission to the intensive care unit after surgery until discharge from the intensive care unit, up to 30 days postoperatively.
Additional or Revision Spine Surgery
Time frame: Up to 24 months after surgery
Perioperative Complications
Time frame: Perioperative/Periprocedural
Operative Parameters
Time frame: Perioperative/Periprocedural
Dynamic Spondylolisthesis
Time frame: 24 month after surgery
Central Stenosis Severity Assessed by the Schizas Classification
Time frame: 24 months after surgery
Foraminal Stenosis Severity Assessed by the Lee Classification
Time frame: 24 months after surgery.
Implant Integrity
Time frame: 24 months after surgery.
Segmental Lordosis
Time frame: 24 months after surgery.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 28 Oct 2026.
- Individual participant dataSharing planned: Yes. Individual participant data underlying the results reported in publications arising from this study, after de-identification, will be made available upon reasonable request to the corresponding investigator. Supporting documents including the study protocol, statistical analysis plan, and data dictionary will also be made available.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Microsurgical Decompression with Extension of Fusion and Microsurgical Decompression Alone in people with Adjacent Segment Disease and Lumbar Spinal Stenosis, run by Charite University, Berlin, Germany at 1 site in Germany.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 12 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 28 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Germany. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Anton Früh, PD MD M.Sc. (+49 030 450 660 376, anton.frueh@charite.de), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Proportion of Participants Achieving at Least 30% Reduction in Oswestry Disability Index (ODI) (time frame: 24 months after surgery). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 28 Oct 2026.