A Prospective Multicenter Cohort Study About Internal Fixation Using FNS Versus MCS for Femoral Neck Fracture

Inclusion Criteria: 1. Age ≥18 years 2. Patients with unilateral femoral neck fractures that will be treated with internal fixation 3. According to AO fracture classification, subjects with the fracture type (31-B) 4. Subjects (with the help of relatives) can understand the informed documents and patient questionnaires. 5. Subjects (with the help of relatives) voluntarily provide written informed consent to participate in the clinical study and authorize the transfer of their information to the sponsor. 6. The investigator believes that the subject can understand the clinical study, is willing and able to complete all research procedures and follow-up visits and can cooperate with the research procedures. 7. In-label use of the MCS and FNS. Exclusion Criteria: 1. Subject does not provide voluntary consent to participate in the study. 2. The researcher believes that the subjects have conditions that affect the participation and follow-up of this study. (for example, the patient lives in a remote area or has difficulty in going back to the hospital for follow-up or does not cooperate with the medical guidance and suggestions of the surgeon.) 3. The subjects were pregnant or lactating women. 4. The researchers believe that the subjects have psychological disorders, which may affect the treatment outcome. 5. Garden classification III and IV of femoral neck fracture patients older than 65 years 6. Concurrent hip osteoarthritis. 7. Fractures where the operative treatment will occur more than three weeks after the primary injury 8. Patients combined with other bone fractures. 9. Pathological fracture (e.g., primary or metastatic tumor) 10. Serious soft tissue injury, judged by the investigator, will impact the union of the fracture, combined open fractures, vascular injury, and combined osteofascial compartment syndrome 11. Multiple systemic injuries judged by researchers not suitable for enrollment. 12. Revision surgeries (for example, due to malunion, nonunion or infection) 13. Concurrent medical conditions judged by researchers not suitable for enrollment, such as: metabolic bone disease, post-polio syndrome, poor bone quality, prior history of poor fracture healing, etc 14. Patients with anaesthetic and surgical contraindications 15. Patients known to be allergic to implant components 16. Patients who are currently using chemotherapeutics or accepting radiotherapy, use systematically corticosteroid hormone or growth factor, or long-term use sedative hypnotics (continuous use over 3 months) or non-steroidal anti-inflammatory drugs (continuous use over 3 months) 17. Intemperance judged by researchers not suitable for enrollment (e.g., excessive daily drinking or smoking, drug abuse); 18. Subjects participated in other clinical studies in the past 3 months, which may affect the outcome and follow-up according to the judgment of researchers. 19. Subjects have significant neurological or musculoskeletal disorders or may have adverse effects on gait or weight-bearing (e.g., muscular dystrophy, multiple sclerosis, cerebral infarction, hemiplegia, Charcot arthropathy, avascular necrosis of the femoral head).