Three Cancellous Screws Versus Four Cancellous Screws for Femoral Neck Fixation

Inclusion Criteria: * Age ≥18 years * Patients with unilateral femoral neck fractures that will be treated with internal fixation * According to AO fracture classification, subjects with the fracture type (31-B) * Subjects (with the help of relatives) can understand the informed documents and patient questionnaires. * 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. * 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. * In-label use of the MCS. Exclusion Criteria: * Subject does not provide voluntary consent to participate in the study. * 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.) * The subjects were pregnant or lactating women. * The researchers believe that the subjects have psychological disorders, which may affect the treatment outcome. * Garden classification III and IV of femoral neck fracture patients older than 65 years * Concurrent hip osteoarthritis. * Fractures where the operative treatment will occur more than three weeks after the primary injury * Patients combined with femoral head fractures(31-C), femoral shaft fractures(32-A/B/C) or femoral trochanteric area fracture (31-A1/A2/A3). * Pathological fracture (e.g., primary or metastatic tumor) * Serious soft tissue injury, judged by the investigator, will impact the union of the fracture, combined vascular injury, and combined osteofascial compartment syndrome * Multiple systemic injuries judged by researchers not suitable for enrollment. * Revision surgeries (for example, due to malunion, nonunion or infection) * 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 * Patients with anaesthetic and surgical contraindications * Patients known to be allergic to implant components * 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) * Intemperance judged by researchers not suitable for enrollment (e.g., excessive daily drinking or smoking, drug abuse); * 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. * 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).