Evaluation of Fracture Migration After Internal Fixation of Femoral Neck Fractures in Younger Adults: A Clinical RCT Using RSA

Evaluation of Femoral Neck Fracture Migration After Internal Fixation With an Angle Stable Implant Compared With Gold Standard Cannulated Cancellous Screws in Young Adults: Study Protocol for a Clinical RCT Using Radiostereometric Analysis

The goal of the clinical trial is to compare different surgical methods for internal fixation of femoral neck fractures in younger adults.

The main question it aims to answer is:

Is internal fixation with the novel implant consisting of three angle stable screws locked together by a plate equal to internal fixation with cancellous screws or a sliding hip screw in younger adults under 65 years of age in terms of fracture migration?

The study will examine how stable the fracture remains during healing. This will be measured by assessing how much the fracture moves after surgery using a highly precise imaging method called radiostereometric analysis (RSA). The study will also record complications and evaluate pain, health related quality of life, and hip function over time.

The participants will be treated with either a novel angle stable implant (Dynaloc), cannulated cancellous screws or sliding hip screw and followed up at 6 weeks, 12 weeks, 6 months and 12 months. Recruitment will continue until 75 participants, 25 in each group, have completed the 12-week follow-up for the primary outcome.

Study Overview

• Status: Recruiting
• Conditions: Hip Fractures; Femoral Neck Fractures; Internal Fixation; Complications
• Intervention / Treatment: Device: Dynaloc implant; Device: Cannulated cancellous screws; Device: Sliding hip screw

Detailed Description

Objective The overall purpose of the study is to assess internal fixation methods for femoral neck fractures in adults under 65 years of age. The primary objective is to compare fracture migration following internal fixation with a novel angle-stable implant (Dynaloc, Swemac) and cannulated cancellous screws (CCS), using fracture migration as the primary outcome.

In addition, a cohort of patients treated with a sliding hip screw (SHS) as part of standard care will be included to provide an additional basis for comparison.

Dynaloc, CCS, and SHS are all CE-marked medical devices used in accordance with the manufacturers' intended use.

Trial design The study is designed as a multicentre, single-blinded randomised controlled trial with radiostereometric analysis (RSA), including an additional prospective cohort.

Patients undergoing internal fixation with Dynaloc or CCS will be randomised, while patients treated with a sliding hip screw will be followed as a separate cohort using the same imaging and follow-up protocol.

Interventions Eligible patients will be randomised to internal fixation with either three CCS or the Dynaloc implant.

Patients who do not undergo randomisation and are treated with SHS as standard care may be included in a prospective cohort and followed according to the study protocol.

All surgical procedures will be performed according to the manufacturers' surgical techniques and instructions for use.

Sample size calculation The primary outcome is shortening of the femoral neck at 12 weeks. A clinically relevant difference is defined as femoral neck shortening greater than 5 mm. Femoral neck shortening in patients treated with CCS is expected to be 5.3 mm (SD 4.5 mm) at 6 weeks, and no further clinically relevant shortening is expected between 6 and 12 weeks.

Using a power of 0.9, a significance level of 0.05, and assuming a maximum femoral neck shortening of 1 mm in the Dynaloc group compared with 5.3 mm (SD 4.5 mm) in the CCS group, a total sample size of 50 randomised patients (25 per group) is required.

In addition, a cohort of 25 patients treated with a sliding hip screw will be included for comparative purposes.

Inclusion will continue until all 50 randomised patients and all 25 cohort patients have completed the 12-week follow-up for the primary outcome. Due to the rarity of femoral neck fractures in this age group, up to approximately 20% additional patients may be included to ensure complete 12-week follow-up.

Randomization/allocation After informed consent is obtained, eligible patients will be enrolled and entered into an electronic database. Patients will be randomised to either CCS or Dynaloc using block randomisation with block sizes of 4 and 6. Randomisation will be stratified by Garden classification (Garden 1-2 vs. 3-4) to account for fracture displacement and by hospital of admission.

The operating surgeon will contact a central coordinator to perform the randomisation prior to surgery and will therefore know the allocated implant before entering the operating theatre.

Blinding Participants and care providers will be blinded to the allocated implant. A standardised description of the surgical procedure will be used. Treatment allocation will remain blinded during statistical analyses.

Data Collection Project staff will collect clinical data, CT scans, and radiostereometric X-rays and perform image analyses using AutoRSA. Screening will be conducted by the admitting physician. Baseline data will be collected during admission and entered directly into REDCap by project personnel.

Patient-reported outcome questionnaires will be distributed electronically via REDCap, with responses automatically uploaded to the database. Follow-up visits will take place in the outpatient clinic, where project personnel will complete and verify data entry.

Statistical methods Treatment groups will remain blinded during statistical analyses. Data distribution will be assessed and results presented accordingly. Continuous outcomes will be analysed using linear mixed-effects models, and categorical variables will be compared using χ² or Fisher's exact tests, as appropriate.

A p-value of <0.05 will be considered statistically significant. Postoperative complication rates will be defined as the combined incidence of complications and reoperations. Mortality will be analysed using Cox regression. Statistical analyses and graphical presentation will be performed using STATA 18 (StataCorp).

• Study Type: Interventional
• Enrollment (Estimated): 75
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Michaela Manalili Hansen, MD; Phone Number: +4560808836; Email: michaela.manalili.hansen@rsyd.dk

Study Locations

• Denmark
  • Aarhus, Denmark
    • Recruiting
    • Aarhus University Hospital
    • Contact: Hansen; Phone Number: +4560808836; Email: michaela.manalili.hansen@rsyd.dk
  • Gødstrup, Denmark
    • Recruiting
    • Regional Hospital Gødstrup
    • Contact: Hansen; Phone Number: +4560808836; Email: michaela.manalili.hansen@rsyd.dk
  • Hvidovre, Denmark
    • Not yet recruiting
    • Hvidovre Hospital
    • Contact: Hansen; Phone Number: +4560808836; Email: michaela.manalili.hansen@rsyd.dk
  • Odense, Denmark
    • Recruiting
    • Odense University Hospital
    • Contact: Hansen; Phone Number: +4560808836; Email: michaela.manalili.hansen@rsyd.dk

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Femoral neck fracture (DS720)
• Age 18-64 years
• Ability to speak and read Danish
• Willingness to participate

Exclusion Criteria:

• Pathological, basicervical or transcervical fracture
• Clinical Frailty Scale ≥5, indicating mild to severe frailty prior to the fracture
• Cognitive impairment that hinders informed consent
• Previous fracture in the ipsilateral femur
• Patients who are unwilling or incapable of following post-operative care instructions.

• Comorbidities making the participant ineligible for internal fixation such as:

  • Material sensitivity, documented or suspected
  • Active or suspected latent infection, sepsis or marked local inflammation in or around the surgical area
  • Compromised vascularity, inadequate skin or neurovascular status
  • Compromised bone stock that cannot provide adequate support and/or fixation of the device due to disease, infection or prior implantation
  • Other physical, mental, medical or surgical conditions that would preclude the potential benefit of surgery.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Dynaloc; Randomisation	Device: Dynaloc implant; Internal fixation with Dynaloc implant
Active Comparator: Cannulated cancellous screws; Randomisation	Device: Cannulated cancellous screws; Internal fixation with two or three cannulated cancellous screws
Active Comparator: Sliding hip screw; Prospective cohort	Device: Sliding hip screw; Internal fixation with a sliding hip screw

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Static fracture migration	Static non-weight bearing fracture migration in a supine set-up	12 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Static fracture migration	Static non-weight bearing fracture migration in a supine set-up	6 weeks
New mobility score	Assessment of gait. 0-9 points	Baseline, 6 weeks, 12 weeks
Modified Harris Hip Score	Measure of hip dysfunction. <70 = poor result; 70-80 = fair, 80-90 = good, and 90-100 = excellent.	Baseline, 6 weeks, 12 weeks
EQ-5D-5L	Health related Quality of Life	Baseline, 6 weeks, 12 weeks
Pain VRS	Pain verbal rating scale 0-10	Baseline, 6 weeks, 12 weeks
Reoperation	Any secondary operation	0-12 weeks
Complication	Any complication (non-union, avascular necrosis of the femoral head, fixation failure)	0-12 weeks
Mortality	Death	0-12 weeks

Collaborators and Investigators

• Sponsor: Odense University Hospital
• Collaborators: Aarhus University Hospital; Gødstrup Hospital; Region of Southern Denmark; Swemac Innovation AB

Study record dates

Study Major Dates

• Study Start (Actual): June 16, 2025
• Primary Completion (Estimated): December 1, 2027
• Study Completion (Estimated): December 1, 2028

Study Registration Dates

• First Submitted: July 22, 2024
• First Submitted That Met QC Criteria: July 25, 2024
• First Posted (Actual): July 26, 2024

Study Record Updates

• Last Update Posted (Actual): January 27, 2026
• Last Update Submitted That Met QC Criteria: January 24, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: hip fracture; femoral neck fracture; internal fixation; radiostereometric analysis
• Additional Relevant MeSH Terms: Wounds and Injuries; Leg Injuries; Fractures, Bone; Femoral Fractures; Hip Injuries; Hip Fractures; Femoral Neck Fractures
• Other Study ID Numbers: 2401073

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No