FINDISC-Pain, Finnish Discectomy Trial on the Benefits and Harms of Surgery in Patients With Lumbar Disc Herniation

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.

• Microdiscectomy (Procedure): 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.
• Placebo-surgery (Procedure): 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

Primary outcomes

• Worst leg pain intensity within past 24-hours (NRS 0-10, where 0 = no pain, 10 = worst possible pain) [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.]: 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)
• Patient acceptable symptom state (PASS) [1, 3 and 6 weeks, and 3, 6 and 12 months post intervention. Primary endpoint at 6 weeks.]: 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).

Secondary outcomes

• Oswestry Disability Index (ODI) (0-100, where 0 = no disability) [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) [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) [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) [Recruitment, 6 weeks and 12 months post intervention]: 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.
• Health-related quality of life (EQ-5D Visual Analogue Scale (EQ VAS), range 0 to 100, where 100 = the best imaginable health state) [Recruitment, 6 weeks and 12 months post intervention]
• Global Perceived Recovery (GPR) (7-point Likert scale, where 1 = completely recovered, 7 = worse than ever) [6 weeks and 12 months post intervention]
• Return-to-work (Yes/No/Part-time/Not working now) [6 weeks, 3, 6 and 12 months post intervention]
• Lower extremity muscle strength [Recruitment and 6 weeks post intervention]: Manual muscle testing for knee extension, ankle dorsiflexion, ankle plantar flexion, hallux extension (scale 0-5, where 0 = no muscle activation, 5 = normal strength)
• Lower extremity motor function [Recruitment and 6 weeks post intervention]: 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.
• Straight leg raise (SLR) test [Recruitment and 6 weeks post intervention]: Positive or negative SLR test during standardized examination (recorded as positive/negative).
• Lower extremity sensory symptoms [Recruitment and 6 weeks post intervention]: Presence of sensory symptoms in the affected leg assessed during clinical evaluation (recorded as Yes/No).
• Harms [From day of surgery through 12 months post-intervention]: 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.

Other outcomes

• Blinding fidelity (methodological measure) [12 months post intervention]: Participant assumed group (study arm) allocation as Microdiscectomy / Placebo / Uncertain
• Magnetic resonance imaging (MRI) [Recruitment, 3 and 12 months]: 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

Sex: All, ages: 18 Years to 60 Years

Inclusion Criteria:

* Age 18-60 years
* Diagnosed unilateral lower extremity radiculopathy (sciatica) secondary to lumbar disc herniation (LDH)
* Single LDH at the level of L3/4, L4/5 or L5/S1 on magnetic resonance imaging
* Symptom duration minimum 6 weeks
* NRS worst leg pain 5 or higher
* Patient has not responded to at least one form of non-operative care
* Patient willing to undergo surgery
* Patient willing and able to give consent and comply with study procedures
* Sufficient proficiency in the language of the study site to provide informed consent and comply with study procedures

Exclusion Criteria:

* Doubtful nerve root compression
* Spinal stenosis or any other confounding spinal condition
* Far lateral disc herniation
* Serious neurological deficit
* Previous spinal surgery
* Any contraindication to MRI
* BMI > 35 or lumbar subcutaneous fat > 50 mm as determined from the MRI
* ASA classification > 2
* Being pregnant

• Teppo Järvinen, Professor, Study director, Helsinki University Central Hospital