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Trial registered on ANZCTR

Registration number

ACTRN12621000069853

Ethics application status

Approved

Date submitted

14/12/2020

Date registered

28/01/2021

Date last updated

14/07/2022

Date data sharing statement initially provided

28/01/2021

Type of registration

Prospectively registered

Titles & IDs

Public title

DISTINCT: Dual Mobility Versus Standard Total Hip Arthroplasty In Femoral Neck Fractures, A Registry-Nested, Cluster-Randomised Trial

Scientific title

DISTINCT: Hip Dislocation Occurrence in Dual Mobility Versus Standard Total Hip Arthroplasty In Femoral Neck Fractures, A Registry-Nested, Cluster-Randomised Trial

Secondary ID [1]

None

Universal Trial Number (UTN)

U1111-1262-1221

Trial acronym

DISTINCT

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Hip fracture

Dislocation

Total Hip Replacement

Condition category

Condition code

Surgery

Other surgery

Injuries and Accidents

Fractures

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

Dual mobility cup (DMC) has been proposed as an alternative, novel design for Total Hip Arthoplasty (THA) that is purported to reduce the risk of dislocation in high-risk populations such as femoral neck fractures. This is achieved by use of a larger head-to-neck ratio and jump distance (i.e. vertical or inferior head displacement required for dislocation) that approximates the size of the natural femoral head allowing an increased range of motion in all directions before dislocation occurs.
The surgery to implant the DMC is the same procedure as implanting a conventional THA, and takes approximately 90 minutes. The only aspect of the procedure that changes is the type of acetabular ('hip socket') liner inserted. The procedure is performed by an Orthopaedic surgeon.
Adherence to the study protocol will be determined using standard Australian Orthopaedic Association National Joint Replacement Registry data (prosthesis details). Both primary and revision surgeries recorded by the AOANJRR are validated by cross-referencing with hospital-level data and unmatched revisions are verified by contacting individual sites.
The study will use a cluster-randomised crossover design. Clusters will consist of individual hospitals. Clusters will be randomised to either the intervention or the comparator. Sites will crossover to the alternate procedure once 16 patients have been recruited to their originally allocated study arm. The number of patients per cluster may vary according to recruitment speeds. For example, a low volume recruitment site may crossover after 8 patients have been recruited, and a high volume recruiment site may crossover after 24 patients have been recruited. This will be accounted for in statistical analyses for an average cluster size of 16 patients per study arm, with 32 patients total anticipated on average per site.

Intervention code [1]

Treatment: Surgery

Comparator / control treatment

Conventional Total Hip Arthroplasty (CTHA) involves replacing the femoral head (ball) and acetabulum (socket) of the hip joint. However, compared to the DMC, there is only one bearing surface between the prosthetic femoral head and acetabulum. The surgical procedure is identical, and takes approximately 90 minutes. CTHA is routinely performed by Orthopaedic surgeons for the treatment of femoral neck fractures. Adherence to the study protocol will be determined using standard Australian Orthopaedic Association National Joint Replacement Registry data (prosthesis details). Both primary and revision surgeries recorded by the AOANJRR are validated by cross-referencing with hospital-level data and unmatched revisions are verified by contacting individual sites.

Control group

Active

Outcomes

Primary outcome [1]

Hip dislocation: identified information collected at the time of primary hip replacement will be used to link Registry (and therefore DISTINCT study) data with hospital level data acquired through state governments or the Australian Institute for Health and Welfare (AIHW) to determine dislocation using patient identifiers.

Timepoint [1]

Within 1 year post-operatively

Secondary outcome [1]

Revision surgery for dislocation: AOANJRR already collects data on almost all joint replacement procedures performed in Australia. The operative data are completed at the time of surgery on a Registry form. The forms include a section where the operating surgeon reports the indication for revision surgery. These forms are collated each month by the hospital and sent to the Registry for data entry into the secure Registry database. Revision surgical procedures are thereafter linked to the primary surgical procedure by Registry staff using patient identifiers. This process will remain unchanged.

Timepoint [1]

Assessed at 1, 2 and 5 years post-operatively

Secondary outcome [2]

Revision surgery for any reason: AOANJRR already collects data on almost all joint replacement procedures performed in Australia. The operative data are completed at the time of surgery on a Registry form. The forms include a section where the operating surgeon reports the indication for revision surgery. These forms are collated each month by the hospital and sent to the Registry for data entry into the secure Registry database. Revision surgical procedures are thereafter linked to the primary surgical procedure. This process will remain unchanged.

Timepoint [2]

Assessed at 1, 2 and 5 years post-operatively

Secondary outcome [3]

Death: the AOANJRR links to the National Death Index (Australian Institute for Health and Welfare) twice a year in order to flag if a patient is deceased. The process is unchanged.

Timepoint [3]

Assessed at 1, 2 and 5 years post-operatively

Secondary outcome [4]

Complications: any unplanned reoperation or readmission related to the surgery. Identified information collected at the time of primary hip replacement will be used to link Registry (and therefore DISTINCT study) data with hospital level data acquired through state governments or the Australian Institute for Health and Welfare (AIHW) to determine dislocation using patient identifiers.

Timepoint [4]

Within 1 year post-operatively

Secondary outcome [5]

Costs: if DMC is found to be superior to conventional THA, the cost-effectiveness will be analysed. The cost-effectiveness of DMC versus CTHA will be analysed using trial data in a separate manuscript to the DISTINCT trial. Direct costs to the hospital for each procedure will be determined from hospital financial records.

Timepoint [5]

Assessed at 1, 2 and 5 years post-operatively.

Eligibility

Key inclusion criteria

1. Displaced femoral neck fracture suitable for conventional THA (e.g. no pre-existing deformity requiring custom or non-standard protheses)
2. Aged 50 years or older
3. Patient meets Australia New Zealand Hip Fracture Guidelines for management of a
displaced intracapsular hip fracture with a total hip replacement:
4. Able to walk independently out of doors with no more than use of a stick prior to the
fracture
5. Not cognitively impaired
6. Medically fit for anaesthesia and the procedure

Minimum age

50 Years

Maximum age

No limit

Sex

Both males and females

Can healthy volunteers participate?

Key exclusion criteria

1. Dementia or other significant cognitive impairment
2. Resident of a permanent residential aged care facility
3. Pathological fracture due to tumour

Study design

Purpose of the study

Treatment

Allocation to intervention

Randomised controlled trial

Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)

Allocation is not concealed.

Methods used to generate the sequence in which subjects will be randomised (sequence generation)

Each site will be randomised with a 1:1 allocation with a computer-generated random sequence. Simple randomisation will be used (no use of blocks, no stratification). The allocation will refer to the first intervention.

Masking / blinding

Blinded (masking used)

Who is / are masked / blinded?

The people analysing the results/data

Intervention assignment

Other

Other design features

Cluster-randomised crossover trial
Sites will not be blinded to group allocation. Patients will be informed of a study comparing two different but common types of THA used for fractured neck of femur.
The statistical analysis will be blinded. The Writing Committee will be blinded and will prepare two separate manuscripts based on the possible group allocations.

Phase

Not Applicable

Type of endpoint/s

Efficacy

Statistical methods / analysis

The analysis for the primary aim will test between-group difference in the proportion of cases sustaining a dislocation of the affected hip within one year post-operatively.
The primary analysis will use cluster summary methods. These methods estimate the treatment effect using cluster level differences and have been shown to be appropriate for cluster randomised crossover trials with rare outcomes and the intracluster and interperiod correlation coefficients expected in this trial. Multiple imputation will be used to account for missing outcome data, using auxiliary variables gathered from routine Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) data (including age, sex, baseline health, pain and function, diagnosis and surgical factors).
Secondary analyses will be performed for the primary outcome, to test for differences in treatment effect between subgroups of patients: surgical approach, ASA grade, BMI grade and gender.
The analysis method will be the same as the primary outcome and will include an interaction term between subgroup and treatment group.
Secondary analyses will include an analysis of all-cause revision, revision for dislocation, and other complications (death, re-operation and readmission rates). Cluster summary methods will be used for all secondary analyses.
If DMC are found to be superior to conventional THA, a cost effectiveness analysis of DMC compared to conventional THA will be performed from a health system perspective, calculating the cost per dislocation saved. The only difference in input costs will be the difference in implant costs, as all other care costs will be equal.

Recruitment

Recruitment status

Recruiting

Date of first participant enrolment

Anticipated

1/02/2021

Actual

1/02/2021

Date of last participant enrolment

Anticipated

1/02/2023

Actual

Date of last data collection

Anticipated

1/02/2028

Actual

Sample size

Target

1536

Accrual to date

1145

Final

Recruitment in Australia

Recruitment state(s)

ACT,NSW,QLD,SA,TAS,WA,VIC

Funding & Sponsors

Funding source category [1]

Charities/Societies/Foundations

Name [1]

Australian Orthopaedic Association National Joint Replacement Registry

Address [1]

South Australian Health and Medical Research Institute (SAHMRI)
North Terrace
ADELAIDE SA 5000

Country [1]

Australia

Primary sponsor type

Charities/Societies/Foundations

Name

Australian Orthopaedic Association

Address

Level 26, 201 Kent St, Sydney NSW 2000

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Sydney Local Health District Ethics Review Committee (RPAH Zone)

Ethics committee address [1]

Research Ethics and Governance Office 
55 Missenden Rd
Royal Prince Alfred Hospital
CAMPERDOWN NSW 2050

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

29/02/2020

Approval date [1]

28/05/2020

Ethics approval number [1]

X20-0162 & 2020/ETH00680

Summary

Brief summary

Fractured neck of femur (FNF) is a common condition, affecting 25,000 Australians per annum. Total hip arthroplasty (THA), which involves replacing the ball and socket of the hip joint, is the current standard of care for fractured neck of femur in community-dwelling patients with minimal co-morbidities.  However, despite superior pain and functional scores compared to the alternative treatment, partial hip replacement (hemiarthroplasty), THA exposes patients to an increased risk of prosthesis dislocation.  Prosthesis dislocation involves separation of the prosthetic head and acetabular cup, and may require a patient to undergo revision THA, a procedure associated with increased costs and morbidity. Dual mobility cups (DMC) are an alternative THA design in common use in Australia, and are hypothesised to reduce the risk of dislocation. This trial will compare the outcomes of conventional THA versus DMCs in the FNF population.

Trial website

Trial related presentations / publications

Public notes

Contacts

Principal investigator

Name

Prof Ian A. Harris

Address

Whitlam Orthopaedic Research Centre
Level 2, Ingham Institute, 1 Campbell St, Liverpool NSW, 2170

Country

Australia

Phone

+61 410698284

Fax

[email protected]

Contact person for public queries

Name

Tamara Hooper

Address

SAHMRI
North Terrace
ADELAIDE SA 5000

Country

Australia

Phone

+61 8 8128 4598

Fax

[email protected]

Contact person for scientific queries

Name

Ian A. Harris

Address

Whitlam Orthopaedic Research Centre
Level 2, Ingham Institute, 1 Campbell St, Liverpool NSW, 2170

Country

Australia

Phone

+61 410698284

Fax

[email protected]

Data sharing statement

Will individual participant data (IPD) for this trial be available (including data dictionaries)?

Yes

What data in particular will be shared?

Primary and secondary outcomes

When will data be available (start and end dates)?

Following dissemination of the results in a peer-reviewed journal (expected publication 2025).
There is no end date planned for availability of data.

Available to whom?

Researchers who make a written request to the Chief Investigator (IAH) for the purposes of collaborative analysis of trial data.

Available for what types of analyses?

Individual patient data meta-analyses

How or where can data be obtained?

Access subject to approval by Chief Investigator (IAH). Ian A. Harris can be contacted at [email protected].

What supporting documents are/will be available?

Doc. No.	Type	Citation	Link	Email	Other Details	Attachment
9922	Study protocol					381041-(Uploaded-03-12-2020-08-16-47)-Study-related document.pdf

Results publications and other study-related documents

Documents added manually

No documents have been uploaded by study researchers.

Documents added automatically

Source	Title	Year of Publication	DOI
Embase	Dual mobility versus conventional total hip arthroplasty in femoral neck fractures (DISTINCT): protocol for a registry-nested, open-label, cluster-randomised crossover trial.	2022	https://dx.doi.org/10.1136/bmjopen-2022-064478

N.B. These documents automatically identified may not have been verified by the study sponsor.

Trial Review

Documents added manually

Documents added automatically