Safety and Efficacy of the ISS Sleeve Augmentation Technique in the Treatment of Thoracolumbar Osteopenic Fractures


Implant anchorage is difficult in patient with osteoporotic bone. To improve the implant bone interface, the ISS stabilization system has been developed. The goal of the study is to investigate the efficacy the ISS augmentation compared to the standard PMMA augmentation of pedicle screws in the treatment of patients suffering from osteoporotic/osteopenic thoracolumbar fracture.

The study has two phases, a pilot phase followed by a pivotal phase. The data will be used to measure clinical and radiological performance and usability of both systems.

Full Title of Study: “Safety and Efficacy of the New ISS Sleeve Augmentation Technique in the Treatment of Osteoporotic/Osteopenic Vertebral Fractures in the Thoraco-lumbar Spine: A Pilot Study and Subsequent Comparison to the Standard PMMA-Screw Augmentation”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Other
    • Masking: Single (Investigator)
  • Study Primary Completion Date: October 15, 2023


  • Device: Augmentation with the ISS Study System
    • Augmentation with the ISS Study System
  • Other: Augmentation with PMMA
    • Augmentation with PMMA (standard)

Arms, Groups and Cohorts

  • Other: Treatment with ISS Sleeve
    • The biocompatible, resorbable ISS sleeve is used for augmentation to enhance screw anchorage. It is melted into the trabecular bone structure of the osteoporotic vertebra using ultrasound. A standard pedicle screw is inserted into the sleeve.
  • Other: Treatment with PMMA
    • The bone cement Polymethylmethacrylat (PMMA) that is injected into the osteoporotic vertebra.PMMA augmentation of pedicle screws is done using standard cannulated and perforated pedicle screws. The cancellous bone surrounding the screw is enhanced with PMMA bone cement to increase screw anchorage.

Clinical Trial Outcome Measures

Primary Measures

  • Change of the bi-segmental kyphosis angle (Correction Loss)
    • Time Frame: Day 3 to 6 Months
    • The evaluation will be done from a comparison of plain x-rays taken post-operatively before discharge (day 3 (± 1 day)) and 6 months post operatively both in upright position. The correction loss of the bi-segmental kyphosis angle will be compared in the ISS Sleeve screw augmentation group and the standard PMMA screw augmentation group.

Secondary Measures

  • Time of x-ray exposure
    • Time Frame: Surgery
    • accumulated duration; from skin incision to skin suture) of patients and medical personnel.
  • Compression rate
    • Time Frame: post-operatively before discharge (day 3 (± 1 day)) compared to 3, 6 and 12 months postoperatively
    • Compression rate of the anterior vertebral body height measured in the lateral x-ray
  • Screw loosening
    • Time Frame: up to 12 months
    • Screw loosening measured following the method of Aghayev et al. The angle between the axes of the pedicle screws and the cranial endplate are measured
  • Evaluation of the functional outcome with the Oswestry Disability
    • Time Frame: baseline, 3 months, 6 months, 12 months
    • Oswestry Disability Index (ODI)
  • Evaluation of the pain level
    • Time Frame: baseline, 3 months, 6 months, 12 months
    • Pain Scale as Visual Analogue Scale (VAS)
  • Evaluation of the clinical outcome
    • Time Frame: baseline, 3 months, 6 months, 12 months
    • SF-12
  • Treatment success
    • Time Frame: at 6 and 12 months postoperatively
    • composite endpoint including the correction loss of the bi-segmental kyphosis angle, the ODI and the occurrence of any device-related serious adverse events

Participating in This Clinical Trial

Inclusion Criteria


1. Age ≥ 50 and ≤ 85, male and female patients

2. Subject is able to understand the risks and benefits of participating in the study and is willing to provide written informed consent.

3. Psychosocially, mentally and physically able to fully comply with the protocol requirements for the duration of the study including adhering to scheduled visits, treatment plan, completing forms and other study procedures.


4. Fractures between the 10th thoracic and 4th lumbar vertebra, both included

5. Bone mineral density equal or above the threshold of 60 mgHA/ccm (central assessment of the screening qCT scan).

6. Fractures with the indication and possibility for augmented bi-segmental dorsal pedicle screw and rod stabilization including kyphoplasty in the broken vertebra

7. All fractures where pedicle screws can be used

Exclusion Criteria


1. Substance use disorders (incl. tobacco abuse >20 cigarettes/day) and alcohol abuse disorders within the last 2 years before randomization.

2. BMI > 35

3. Permanent or progressive neurologic deficits (incl. upper motor neuron disease and myelopathy)

4. Known Creutzfeldt Jacob Disease

5. Systemic infections:

  • Known infection with human immunodeficiency virus (HIV) or, hepatitis B or C requiring treatment
  • Any active infection requiring the use of parenteral anti-microbial agents or that is > grade 2 Common Terminology Criteria for Adverse Events (CTCAE) Version 4.03

6. Rheumatoid arthritis or known disorders of bone metabolism (excl. osteopenia/osteoporosis, Vitamin D deficiency)

7. Radiation therapy of the spine in medical history

8. Contraindications to pedicle screw and rod stabilization

9. Breast feeding, pregnancy or child-bearing potential (female patients of childbearing potential and male patients with a partner of child bearing potential must agree to use a highly effective contraceptive method).

10. A compromised immune system or a therapy with systemic corticosteroids or immunosuppressants

11. Active malignancy or history of malignancy (excl. Basalioma as a semi-malignant tumor) <2 years ago from time of randomization

12. Known allergy to any component of the investigational device

13. History of severe allergy, anaphylactic reactions and hypersensitivity reactions experienced in previous surgical interventions.

14. Other concurrent severe and/or uncontrolled medical conditions (e.g. insufficiently treated diabetes (HbA1c > 8 %), active or uncontrolled infection) that could cause unacceptable safety risks or compromise compliance with the protocol

15. Participation in other clinical investigations for drugs or devices


16. Fracture age > 3 months

17. Major surgery to the spine planned for at least 12 months following enrolment

18. Any treatment of the fracture other than that specified in the inclusion criteria (e.g. index screws in the fractured vertebra, vertebroplasty, additional ventral stabilization)

19. Severe spinal deformations or fusion at the target vertebral or adjacent segments

20. Previous operations at the spine in the target or adjacent vertebrae

21. Infections or inflammatory processes at vertebral bodies

Gender Eligibility: All

Minimum Age: 50 Years

Maximum Age: 85 Years

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • Nexilis AG
  • Provider of Information About this Clinical Study
    • Sponsor
  • Overall Official(s)
    • Richard Lindtner, M.D, Principal Investigator, Department of Trauma Surgery, Medical University of Innsbruck, Austria
    • Ferdinand Krappel, M.D, Principal Investigator, Spitalzentrum Oberwallis, Brig, Switzerland
  • Overall Contact(s)
    • Sabine Goldhahn, M.D, +41619220509,

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