This study is an intervention domain of the Musculoskeletal Adaptive Platform Trial. The primary goal of this pragmatic, randomized, open-label, comparative effectiveness trial is to evaluate if arthroplasty is superior to internal fixation when used to treat minimally displaced femoral neck fractures in older adults ≥60 years old. We hypothesize that arthroplasty will reduce death, preserve ambulation, increase days alive and out of hospital, and improve health status compared to internal fixation within 4 months and 12 months from randomization.

The Musculoskeletal Adaptive Platform Trial (MAPT) is an adaptive platform trial protocol that enables the simultaneous evaluation of multiple interventions (i.e., intervention domains) within a consistent infrastructure. Each intervention being evaluated in the MAPT will have an intervention domain protocol that describes additional eligibility criteria, interventions, secondary outcomes, and statistical stopping rules. The overarching objective of the MAPT trial platform is to incrementally decrease decisional uncertainty and identify treatments that will optimize patient outcomes. The platform focuses on the comparative effectiveness of available treatment options.

Adult patients aged 60 years or older with a low-energy minimally displaced femoral neck fracture treated with surgery are eligible for the FASTER-HIP intervention domain. Nearly half of all elderly hip fractures are femoral neck fractures, and approximately 20% are minimally displaced. Internal fixation has remained the treatment of choice for these injuries because these fractures can be fixed in situ, and the surgical implants can be inserted with little surgical dissection. Patients treated with internal fixation experience high complication rates, with the pooled risk of reoperation and mortality each above 14%. Preliminary data have suggested arthroplasty for minimally displaced fractures may lead to better patient outcomes, including improved ambulation, fewer reoperations, and a lower risk of death compared to internal fixation. While the preliminary data supporting the use of arthroplasty for minimally displaced fractures is promising, the necessary evidence to make this practice change remains lacking.

FASTER-HIP is a pragmatic, randomized, open-label, comparative effectiveness trial comparing hip arthroplasty versus internal fixation for minimally displaced femoral neck fractures. Randomization in this domain occurs in a 1:1 ratio (hip arthroplasty:internal fixation). The primary outcome is a composite of death within 120 days, ambulation status at 120 days, and days alive and out of hospital within 120 days of randomization. The primary outcome will be hierarchically assessed using the Win ratio. Secondary outcomes include the same composite at 365 days, individual components of the composite, health-related quality of life (EQ-5D-5L), and pain scores during hospitalization.

Inclusion Criteria:

• 60 years of age or older undergoing surgery due to a minimally displaced femoral neck fracture
• The patient has a health condition affecting physical mobility.
• Complete fracture of the femoral neck (AO/OTA 31B) confirmed with anteroposterior and lateral hip radiographs, computed tomography, or magnetic resonance imaging.
• Minimally displaced fracture that could be, in the judgment of the attending surgeon, managed with either arthroplasty or in situ internal fixation without reduction.
• Low energy injury mechanism.
• Surgeons with expertise in internal fixation and total hip arthroplasty or hemiarthroplasty are available to perform surgery.

Exclusion Criteria:

• The patient is not clinically suitable for either compared treatment.
• Expected injury survival of less than 12 months.
• Terminal illness with expected survival of less than 12 months.
• Incarceration.
• Unable to obtain informed consent due to language barriers.
• Unable to obtain informed consent because the legally authorized representative was unavailable.
• Problems, in the judgment of the study personnel, with maintaining follow-up with the patient.
• Currently enrolled in a study or intervention domain that does not permit co-enrollment.
• Prior enrollment in the specific platform trial intervention domain.
• Patient or legally authorized representative did not provide informed consent (declined participation).
• Eligible patient or legally authorized representative was not approached within the screening window (missed participant).
• Other reasons to exclude the patient, as approved by the data coordinating center.
• Associated lower extremity injury that prevents post-operative weight-bearing.
• Retained hardware around the hip that precludes either study treatment.
• Infection around the hip (soft tissue or bone).
• Pathologic fracture with a lytic lesion in the femoral neck that precludes internal fixation.
• Injury did not occur within 21 days of screening.
• Patient is too ill, in the judgment of the attending surgeon, for internal fixation.
• Patient is too ill, in the judgment of the attending surgeon, for arthroplasty.

The participant, treating clinicians, the research team, and the outcome assessors will not be blinded to the treatment allocation and outcome assessments. The data analysts and those interpreting the results of the trial will be blinded.