A displaced femoral neck fracture is a severe injury affecting the upper part of the thigh bone (femur). The femoral neck is the short segment connecting the ball of the hip joint (femoral head) to the main shaft of the femur. A fracture is classified as “displaced” when the broken bone fragments are completely separated and misaligned. This injury demands immediate medical attention due to the high risk of serious complications and the need for urgent surgical intervention. Prompt treatment is necessary to minimize pain, restore mobility, and prevent long-term joint damage.
Understanding the Injury and Risk Factors
The anatomy of the femoral neck makes fractures in this area troublesome, especially when displaced. The blood supply to the femoral head runs along the neck via small vessels. When a fracture is displaced, these vessels are frequently torn, compromising blood flow to the femoral head. This disruption is a major factor determining the complexity of treatment and the potential for complications.
Femoral neck fractures are most commonly associated with low-energy falls in older adults. The predisposing factor in this population is osteoporosis, which weakens the bone structure, making it susceptible to fracture from minimal trauma. Most hip fractures occur in individuals over 50, with women being more frequently affected. Younger patients typically sustain this injury from high-energy trauma, such as car accidents or falls from a significant height.
Immediate Medical Assessment
A patient with a displaced femoral neck fracture usually presents with severe pain and an inability to bear weight on the affected leg. A noticeable deformity is often present, where the injured leg appears shorter and is rotated outward. The initial medical assessment begins with a physical examination, followed immediately by imaging studies to confirm the diagnosis. Standard X-rays of the pelvis and hip are the first line of diagnostic tools.
Imaging helps determine the extent of the damage and classify the fracture, guiding subsequent treatment decisions. Classification systems categorize the fracture based on the degree of displacement and stability. If X-rays are inconclusive but clinical suspicion remains high, a CT scan or MRI may be used to identify occult fractures or better delineate the fracture pattern.
Surgical Repair and Replacement Strategies
Surgery is required to treat a displaced femoral neck fracture, and the choice of procedure depends largely on the patient’s age and overall health status. The two main surgical strategies are internal fixation and arthroplasty, also known as hip replacement. The goal of surgery is to stabilize the fracture and restore the patient’s ability to mobilize quickly.
Internal fixation uses surgical screws, pins, or plates to hold the fractured bone fragments together, allowing the patient’s own bone to heal. This bone-preserving method is the preferred option for younger, more active patients who have a higher potential for fracture healing. However, internal fixation carries the risk of failure if the bone fragments do not unite or if the blood supply to the femoral head is permanently damaged.
Arthroplasty involves replacing the damaged joint with a prosthetic implant. This is the standard treatment for most older patients, especially those with pre-existing osteoporosis or lower activity levels. A hemiarthroplasty replaces only the ball of the joint (femoral head), while a total hip arthroplasty replaces both the ball and the socket. Arthroplasty reduces the risk of needing a second surgery due to healing complications, offering a predictable recovery path.
Managing Post-Surgical Concerns
Despite successful surgery, patients must be monitored for specific post-operative complications unique to this injury. The primary concern following internal fixation is Avascular Necrosis (AVN) of the femoral head. AVN occurs when the blood supply is so severely damaged by the fracture displacement that the bone tissue dies, often requiring a later total hip replacement. The risk of AVN is high following internal fixation of displaced fractures, demonstrating the severity of the initial blood supply damage.
Another complication is non-union, which is the failure of the bone fragments to heal together. This is significantly more likely in displaced fractures compared to non-displaced ones. For those who undergo arthroplasty, the concerns are implant-specific, including dislocation of the new joint or, in the long term, implant failure or loosening. Long-term follow-up is necessary since AVN can take two to three years to become apparent on X-rays.
Recovery and Rehabilitation Timeline
Recovery begins immediately after surgery, often with the patient starting mobility exercises within 24 to 48 hours. Pain management is a focus during the initial hospital stay, involving a combination of medications to ensure comfort during movement. The hospital stay typically lasts one to two days, with patients then transitioning to a skilled nursing facility, rehabilitation hospital, or home care depending on their safety and support needs.
Physical therapy (PT) and occupational therapy (OT) are central to the rehabilitation process, aiming to restore strength and range of motion. Patients who receive arthroplasty are often allowed to bear weight on the leg as tolerated almost immediately, accelerating their return to walking. For those with internal fixation, weight-bearing restrictions may be more cautious to allow the bone to heal, potentially taking up to 12 weeks for full weight tolerance. Full recovery, including a return to most independent daily activities, is expected to take approximately three to six months.