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Monoaxial vs. Polyaxial Percutaneous Hybrid Stabilization

ConditionsThoracolumbarFractures in the Elderly
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age60+
SponsorMedical University Innsbruck

About this trial

Vertebral body fractures in older adults mostly affect the thoracolumbar junction and are challenging to treat due to osteoporosis and other comorbidities. Treatment options range from conservative approaches to minimally invasive procedures like vertebroplasty or balloon kyphoplasty, as well as surgical techniques such as posterior or combined stabilization. A common method for more severe fractures (from OF3 onwards) is percutaneous bisegmental hybrid stabilization using cement-augmented pedicle screws and balloon kyphoplasty. Polyaxial screws are easier to implant but offer less biomechanical stability. In contrast, monoaxial screws provide greater stiffness, allowing better correction of kyphosis and restoration of vertebral body height. The study compares radiological and clinical outcomes in patients aged 60 and older with thoracolumbar fractures (T11-L4) between monoaxial and polyaxial hybrid stabilization. The primary goal is to evaluate and compare the degree of kyphosis correction six months after surgery.

Eligibility criteria

This trial does not accept healthy volunteers

Qualifiers

Age ≥ 60 years (male and female patients)

Ability to understand nature, risks, and benefits of study participation and to provide written informed consent.

Psychosocially, mentally, and physically capable of complying with all study requirements, including scheduled follow-up visits, completion of forms, and participation in all procedures as defined by the protocol.

Ambulatory prior to fracture, with or without the use of assistive devices

Disqualifiers

Body mass index (BMI) > 35

Permanent or progressive neurologic deficits (including upper motor neuron disease and myelopathy)

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

History of radiation therapy to the spine

Trial design

Design model

Parallel

Treatments tested in this trial

  • Monoaxial instrumentation - the M.U.S.T. Monoaxial Pedicle Screw Cannulated (Medacta International SA, Switzerland)

    Device

    In this study, fractures between the 11th thoracic (T11) and 4th lumbar (L4) vertebra (both included) will be treated surgically using either monoaxial or polyaxial bisegmental hybrid stabilization. Hybrid stabilization consists of posterior cement-augmented pedicle screw instrumentation combined with balloon kyphoplasty of the fractured vertebral body. For bisegmental hybrid stabilization, standard cannulated and perforated pedicle screws, either monoaxial (M.U.S.T. Monoaxial Pedicle Screw Cannulated (Medacta International SA, Switzerland)) or polyaxial (M.U.S.T. LT Pedicle Screw System (Medacta International SA, Switzerland)), will be placed in the vertebrae adjacent to the fractured vertebral body.

  • Polyaxial instrumentation - the M.U.S.T. LT Pedicle Screw System (Medacta International SA, Switzerland)

    Device

    In this study, fractures between the 11th thoracic (T11) and 4th lumbar (L4) vertebra (both included) will be treated surgically using either monoaxial or polyaxial bisegmental hybrid stabilization. Hybrid stabilization consists of posterior cement-augmented pedicle screw instrumentation combined with balloon kyphoplasty of the fractured vertebral body. For bisegmental hybrid stabilization, standard cannulated and perforated pedicle screws, either monoaxial (M.U.S.T. Monoaxial Pedicle Screw Cannulated (Medacta International SA, Switzerland)) or polyaxial (M.U.S.T. LT Pedicle Screw System (Medacta International SA, Switzerland)), will be placed in the vertebrae adjacent to the fractured vertebral body.

Treatment groups

44 Participants
are divided into 2 treatment groups
Group A: Arm A: Monoaxial hybrid stabilizationActive comparator 1 intervention
Group B: Arm B: Polyaxial hybrid stabilizationActive comparator 1 intervention

Trial outcomes

Primary outcomes

1

Overall bisegmental kyphosis correction

Overall bisegmental kyphosis correction (OKC) at 6 months postoperatively: The difference between preoperative bisegmental Cobb angle (BCA) upright and BCA at 6 months (upright) postoperatively describes the overall bisegmental kyphosis correction (OKC) at 6 months postoperatively.

Time frame
6 month

Secondary outcomes

1

Radiological outcome - Bisegmental Cobb Angle (BCA)

Measured preoperatively (on both supine (BCApreop supine) and upright (BCA) radiographs), after postoperative mobilization, and at 6 weeks, 3 months, 6 months, and 12 months postoperatively Defined as the angle between the superior endplate of the vertebral body above and the inferior endplate of the vertebral body below the fractured vertebra.

Time frame
1 Year
2

Radiological outcome - Surgical bisegmental kyphosis correction (SKC)

Defined as: Preoperative BCApreop\_upright minus BCA after postoperative mobilization in degrees. Both measured on upright radiographs.

Time frame
1-2 weeks after post-op mobilization
3

Radiological outcome - Loss of bisegmental kyphosis correction

Defined as: BCA after postoperative mobilization minus BCA at 6-month FU in degrees

Time frame
6 month
4

Radiological outcome - overall bisegmental kyphosis correction (OKC) supine

Defined as: Preoperative BCApreop supine (measured on preoperative supine radiographs) - BCA at 6 months postoperatively in degrees.

Time frame
6 month

Other outcomes

Sponsors and contacts

Click on the lead sponsor to view all of their trials.

Medical University Innsbruck

Lead sponsor

Source ClinicalTrials.gov
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