An interventional study of Microdiscectomy and Placebo-surgery in Lumbar Disc Herniation With Radiculopathy and Sciatica, sponsored by Helsinki University Central Hospital. Recruiting at 1 site in Finland. Open to participants aged 18 Years to 60 Years. Per ClinicalTrials.gov, last updated 2026-05-22.
Sponsored by Helsinki University Central Hospital · Not applicable, Interventional, and Treatment
The FINDISC trial studies whether common back operation, microdiscectomy, is effective and safe for treating sciatica caused by a lumbar disc herniation. The study includes people whose leg pain has not improved after at least six weeks of non-surgical treatment.
The FINDISC trial aims to recruit and randomly allocate 122 participants to receive either the actual operation (discectomy) or a placebo (sham) surgery. The placebo (sham) procedure involves anesthesia and an approach similar to the real operation, but no removal of disc material or bone. Participants and healthcare staff, excluding the surgical team, will not know which treatment was given. The study compares pain relief, recovery, daily functioning, quality of life, and harms between the two groups.
The goal of the study is to provide reliable evidence to help patients and clinicians decide whether microdiscectomy offers meaningful benefits compared with placebo surgery.
FINDISC is a randomized, placebo-surgery-controlled clinical trial evaluating the efficacy and safety of microdiscectomy for lumbar disc herniation causing sciatica. The trial includes adults with persistent sciatica symptoms that have not resolved despite at least six weeks of nonoperative care.
Sciatica caused by lumbar disc herniation is a common and disabling condition that can result in prolonged pain, functional limitations, and absence from work. Although most patients improve without surgery, microdiscectomy is frequently offered to patients with ongoing symptoms, and the use of this procedure varies substantially across countries and healthcare systems. Previous randomized trials suggest that surgery may provide faster symptom relief than nonoperative treatment; however, the magnitude and durability of this benefit remain uncertain. Most existing studies are unblinded and have high rates of crossover from nonoperative care to surgery, which limits the ability to determine the true treatment effect of the surgical procedure itself. Because surgical interventions are associated with placebo effects, particularly for subjective outcomes such as pain and perceived recovery, a placebo- surgery-controlled trial is needed to distinguish the specific effects of microdiscectomy from nonspecific effects related to undergoing surgery.
Participants are randomized in a 1:1 ratio to receive either conventional microdiscectomy or placebo surgery. The placebo procedure is designed to mimic surgery but does not include entry to the spinal canal, i.e. removal of disc material or bone. Participants, healthcare professionals involved in post-operative care, outcome assessors, data analysts, and investigators interpreting the results are blinded to treatment allocation. The surgical team performing the procedure is not blinded and has no role in further care and follow-up of the participants.
Outcomes assessed include pain, patient acceptable symptom state (PASS), global perceived recovery, disability, health-related quality of life, and the frequency of serious adverse events and reoperations. The study uses a superiority design, with the hypothesis that microdiscectomy leads to faster symptom relief than placebo surgery while maintaining an acceptable safety profile.
All procedures are performed at tertiary spine centers by experienced orthopedic or neurosurgeons. Post-operative care follows standard hospital practice, with general guidance provided to ensure consistency across sites.
Eligible patients who decline randomization are invited to participate in a parallel observational cohort, from which only baseline data are collected to assess potential selection bias.
A pilot phase enrolling 30 participants at one center is conducted to assess feasibility and safety. If no major protocol changes are required, data from the pilot phase will be included in the main trial analyses.
Participant safety is overseen by an independent Data Safety Monitoring Board (DSMB), which monitors adverse events and approves the statistical analysis plan. Trial data are collected by trained research staff blinded to treatment allocation and stored in a secure electronic data capture system.
149 studies on the registry are indexed under Sciatica; 31 are open to participants now.
This study's planned enrollment of 122 is above the median of 68 across 122 interventional studies indexed under Sciatica.
Browse Sciatica studies →Helsinki University Central Hospital is the lead sponsor of 311 studies on the registry; 61 are open to participants now.
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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.
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.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
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.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ASA physical status
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Lumbar microdiscectomy
Procedure: Microdiscectomy
Placebo-surgery
Procedure: Placebo-surgery
Lumbar microdiscectomy involves a surgical approach with skin and adipose layer incision, and subperiosteal dissection of posterior spinal muscles. After the approach the intervention involves lumbar spinal canal entry, resection of ligamentum flavum and removal of herniated disc fragments. Removal of bone from lamina and intervertebral disc space entry are performed only when necessary.
The placebo-surgery procedure involves an identical incision and approach as in the microdiscectomy group, but it does not include entry to the spinal canal, and no removal of disc material or bone
Worst leg pain intensity within past 24-hours (NRS 0-10, where 0 = no pain, 10 = worst possible pain)
Worst leg pain intensity will be measured using a 11-point Numeric Rating Ccale (NRS 0-10, where 0 = no pain, 10 = worst pain imaginable)
Time frame: Recruitment, 1 day pre intervention, and 1 day, and 1, 3 and 6 weeks, and 3, 6 and 12 months post intervention. Primary endpoint at 6 weeks.
Patient acceptable symptom state (PASS)
PASS will be assessed by asking "Thinking about your recovery from back surgery - would you be satisfied with your current symptoms status (as experienced in the past 24-hours)?" Recorded as Yes / No. Further analysis will report the proportion of participants reporting a satisfactory symptom state at the primary endpoint (responder analysis).
Time frame: 1, 3 and 6 weeks, and 3, 6 and 12 months post intervention. Primary endpoint at 6 weeks.
Oswestry Disability Index (ODI) (0-100, where 0 = no disability)
Time frame: Recruitment, 1 day pre intervention, and 6 weeks, and 3, 6 and 12 month post intervention
Average leg pain intensity in past 24-hours, (NRS 0-10, where 0 = no pain, 10 = worst possible pain)
Time frame: Recruitment, 1 day pre intervention, and 1 day, 1, 3 and 6 weeks, 3, 6, and 12 months post intervention
Back pain intensity in past 24-hours, (NRS 0-10, where 0 = no pain, 10 = worst possible pain)
Time frame: Recruitment, 1 day pre intervention, and 1 day, 1, 3 and 6 weeks, 3, 6, and 12 months post intervention
Health-related quality of life (EuroQol 5-Dimension 5-Level (EQ-5D-5L) index value)
EQ-5D-5L questionnaire, Finnish language version, using the Swedish value set. Score ranges from values below 0 (health states considered worse than death) to 1.00 (full health), where higher scores indicate better health-related quality of life.
Time frame: Recruitment, 6 weeks and 12 months post intervention
Health-related quality of life (EQ-5D Visual Analogue Scale (EQ VAS), range 0 to 100, where 100 = the best imaginable health state)
Time frame: Recruitment, 6 weeks and 12 months post intervention
Global Perceived Recovery (GPR) (7-point Likert scale, where 1 = completely recovered, 7 = worse than ever)
Time frame: 6 weeks and 12 months post intervention
Return-to-work (Yes/No/Part-time/Not working now)
Time frame: 6 weeks, 3, 6 and 12 months post intervention
Lower extremity muscle strength
Manual muscle testing for knee extension, ankle dorsiflexion, ankle plantar flexion, hallux extension (scale 0-5, where 0 = no muscle activation, 5 = normal strength)
Time frame: Recruitment and 6 weeks post intervention
Lower extremity motor function
Lower extremity motor performance assessed during standardized clinical examination, including: ability to perform squat-to-stand, ability to walk on toes and ability to walk on heels. Each component will be recorded as Yes / No and analyzed separately.
Time frame: Recruitment and 6 weeks post intervention
Straight leg raise (SLR) test
Positive or negative SLR test during standardized examination (recorded as positive/negative).
Time frame: Recruitment and 6 weeks post intervention
Lower extremity sensory symptoms
Presence of sensory symptoms in the affected leg assessed during clinical evaluation (recorded as Yes/No).
Time frame: Recruitment and 6 weeks post intervention
Harms
Harms occurring during the 12-month follow-up period. Harms will include pre-specified intra- and perioperative complications and events identified through participant questionnaires, unprompted participant contact, or medical record review. Events will be classified as adverse events (AE), serious adverse events (SAE), or suspected unexpected serious adverse events (SUSAR). Attribution will be categorized as: not related, unlikely related, possibly related, probably related, or definitely related to the intervention. Recorded as number of events.
Time frame: From day of surgery through 12 months post-intervention
Blinding fidelity (methodological measure)
Participant assumed group (study arm) allocation as Microdiscectomy / Placebo / Uncertain
Time frame: 12 months post intervention
Magnetic resonance imaging (MRI)
Radiological assessment for lumbar disc herniation as Yes/No. If yes, further assessment of side (right / left), level (L3/4, L4/5, L5/S1) and type of hernia (protrusion / extrusion / sequestered). Also if yes, nerve root compression assessed on a 4-point scale: Certain / Probable (likelihood \> 50%) / Possible (likelihood \< 50%) / Definitely not
Time frame: Recruitment, 3 and 12 months
Plan to share: Yes — All collected IPD provided that current legislation permits it.
Supporting information: Study protocol, Statistical analysis plan, Informed consent form, Analytic code
Time frame: After publication of main results, to be specified later.
Access criteria: To be determined.
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