RCT Study of the Gelstix™ Device to Treat Chronic Discogenic Low Back Pain GelStix Study (GelStix)

  • End date
    Dec 11, 2025
  • participants needed
  • sponsor
    Ospedale Regionale di Lugano
Updated on 11 March 2022


Degenerative Disc Disease is one of the most common spinal pathologies, affecting up to 10-15 % of adults. The purpose of this study is to evaluate the efficacy of treatment with the GelStix™ device in a patient population with discogenic pain that had no benefit from conservative care.


Degenerative Disc Disease (DDD) is one of the most common spinal pathologies, affecting up to 10-15 % of adults. The degeneration is associated with diminished water-binding capabilities of the nucleus pulpous leading to disc dehydration, volume reduction, changes in cellular activity, biomechanical changes and painful symptoms. Patients are initially treated with non-surgical pain-management techniques, such as anti-inflammatory medications and physical therapy, but these therapies often provide only temporary relief. When non-surgical intervention fails, fusion or total disc arthroplasty are often prescribed, both of which are highly invasive surgeries with significant associated morbidity. Clearly, a meaningful solution for the treatment gap existing between conservative care and invasive surgical intervention is needed.

The purpose of this study is to evaluate the efficacy of treatment with the GelStix™ device in a patient population that had no benefit from conservative care.

The primary objective of this study is to quantify the reduction in lumbar pain in a GelStix™ treatment group compared with a control group receiving a saline solution injection as placebo.

The secondary objectives are to assess:

  • Disability, using the Oswestry Disability Index (ODI)
  • Quality of life (QoL), quantified with the European Quality of Life Five Dimension Five Level Scale (EQ-5D-5L).
  • The Patient's Global Impression of Change (PGIC) scale. This scale assesses the patient's own evaluation of improvement or deterioration over time on a 7-point Likert Scale rated from 'very much improved' to 'very much worse'.
  • The use of pain medication
  • The disc degeneration process will be assessed by means of MRI twelve months after treatment compared to baseline. Pfirrmann grade, disc height, and the presence of high intensity zones, Modic signs, and Schmorl's nodes will be recorded.
  • The incidence and severity of complications and adverse events

The total expected number of patients to be randomized is 72. Taking into account a relevant difference of 1.5 between groups on the NRS, with an SD of 2, 30 patients per group (60 patients in total) will be required to detect a statistically significant difference with a power of 80% at an alpha of 5% (two-tailed) for unpaired Student's T test. Taking into account a 20% drop out rate, 72 patients are expected to be randomized for this study.

The estimated duration for the investigational plan (from start of screening of first participant to end of follow-up of last participant) is 24 months.

Condition Degeneration of Lumbar Intervertebral Disc
Treatment Placebo, GelStix™ Nucleus Augmentation Device
Clinical Study IdentifierNCT02763956
SponsorOspedale Regionale di Lugano
Last Modified on11 March 2022


Yes No Not Sure

Inclusion Criteria

discogenic pain caused by one or two levels of degenerative disc disease, confirmed by MRI and positive discography
failure to have symptoms resolved or reduced following at least 12 weeks of conservative care (pain medication and/or physical therapy)
negative medial branches block results
baseline Numeric Rating Scale (NRS) pain score ≥5/10

Exclusion Criteria

disc herniations
annular tear (greater than Grade 4 Modified Dallas Grading)
coagulopathy or oral anticoagulant therapy (except low-dose acetylsalicylic acid) in conditions that do not allow for a temporary discontinuation
previous lumbar surgery
disc height less than 5 mm at the treatment level or less than 50% the original height
BMI (Body Mass Index (kg/m2) of ≥ 35
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