Monoaxial vs. Polyaxial Percutaneous Hybrid Stabilization

NCT07408726 | Not Yet Recruiting

• 1 other identifier: Mono vs polyaxial PHS
• Study Type: interventional
• Target: 44
• Locations: 0 countries
• Sites: N/A

Brief Summary

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.

Conditions

Thoracolumbar; Fractures in the Elderly

Keywords

Thoracolumbar fractures; Percutaneous hybrid stabilization

Outcome Measures

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.

  6 month

Secondary Outcomes (23)

• Radiological outcome - Bisegmental Cobb Angle (BCA)

  1 Year

• Radiological outcome - Surgical bisegmental kyphosis correction (SKC)

  1-2 weeks after post-op mobilization

• Radiological outcome - Loss of bisegmental kyphosis correction

  6 month

• Radiological outcome - overall bisegmental kyphosis correction (OKC) supine

  6 month

• Radiological outcome - Surgical bisegmental kyphosis correction (SKC) supine

  1-2 weeks after post-op mobilization

Study Arms (2)

Arm A: Monoaxial hybrid stabilization

ACTIVE COMPARATOR

Monoaxial pedicle screw hybrid stabilization is a routinal instrumentation technique and will be compared to the polyaxial hybrid stabilization system, that is an routinal instrumentation at the site as well.

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

Arm B: Polyaxial hybrid stabilization

ACTIVE COMPARATOR

Polyaxial pedicle screw hybrid stabilization is a routinal instrumentation technique and will be compared to the monoaxial hybrid stabilization system, that is an routinal instrumentation at the site as well.

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

Interventions

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.

Arm A: Monoaxial hybrid stabilization

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.

Arm B: Polyaxial hybrid stabilization

Eligibility Criteria

• Age: 60 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Patient-related criteria:
• 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
• Fracture-related criteria:
• Acute vertebral fractures located between T11 and L4 (inclusive)
• Fractures deemed suitable for bisegmental hybrid stabilization based on clinical and radiological assessment - primarily OF type 3 and type 4 fractures according to DGOU classification; type 2 and 5 fractures may also be included based on individual evaluation, with the final treatment decision left to the discretion of the treating surgeon.

You may not qualify if:

• Patient-related criteria:
• 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
• History of alcohol or drug abuse within the last 2 years prior to randomization
• Current therapy with high-dose systemic corticosteroids (e.g., \>10 mg/day prednisone equivalent for more than 3 months)
• Ongoing or planned treatment with cytotoxic chemotherapy (excluding biologicals, immunotherapy, or targeted agents) at the time of enrollment
• Known allergy to any component of the spinal instrumentation
• Participation in other clinical investigations (drug or device) that may interfere with the outcomes of this study
• Fracture-related criteria:
• Vertebral fractures associated with neurological deficits
• Fracture age \> 4 weeks at the time of enrollment
• Pathological fractures due to spinal infection or metastatic bone disease
• Planned major spinal surgery within 12 months of enrollment

Sponsors & Collaborators

• Medical University Innsbruck: lead

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: A Randomized, Single-Blind Pilot Study

Study Record Dates

• First Submitted: September 17, 2025
• First Posted: February 13, 2026
• Study Start: May 1, 2026
• Primary Completion (Estimated): September 1, 2028
• Study Completion (Estimated): November 1, 2028
• Last Updated: April 9, 2026

Record last verified: 2025-09