The sacrum is a large, triangular bone at the base of the spine, nestled between the hip bones, forming the back wall of the pelvis. Formed by five fused vertebrae, it connects the spine to the lower body. A sacrum fracture is a break or crack in this bone, which can compromise the stability of the pelvic ring.
Understanding the Sacrum and Fracture Types
Sacrum fractures are categorized based on the mechanism of injury.
High-Energy Trauma Fractures
These result from significant force, such as a motor vehicle collision or a fall from height. These injuries often involve displacement of bone fragments and frequently occur alongside other severe injuries to the pelvic ring, making them unstable.
Insufficiency Fractures
This type occurs when low-level stress is applied to weakened bone. Insufficiency fractures are common in older adults with osteoporosis, which reduces bone density. They can also be seen in patients who have undergone radiation therapy. Unlike high-energy injuries, these fractures often happen without a specific traumatic event and are generally considered stable. The mechanism of injury dictates the potential for associated nerve damage and the complexity of the required treatment plan.
Identifying the Symptoms
The most common symptom of a sacrum fracture is severe pain in the lower back, hips, or buttocks. This discomfort is often deep and aching, intensifying significantly when the patient attempts to sit, stand, or bear weight. Slight movements can cause bone fragments to shift, leading to sharp pain.
Since the sacrum protects the lower spinal nerves, fractures can result in neurological symptoms. Patients may experience numbness, tingling, or weakness radiating down one or both legs, corresponding to damaged nerve roots. Severe cases involving significant fracture displacement or central canal involvement can compress the sacral nerves, potentially causing difficulty with bladder or bowel control. Loss of control requires immediate medical evaluation and intervention.
Diagnostic Procedures and Treatment Options
Confirming a sacrum fracture often starts with standard X-ray imaging. However, X-rays frequently fail to show non-displaced or subtle fractures clearly due to the complex, overlapping bone structures of the pelvis. Radiograph sensitivity is low, especially in older patients with osteoporosis.
To accurately visualize the injury’s extent and any compromise to the pelvic ring, a Computed Tomography (CT) scan is typically necessary. The CT provides detailed cross-sectional images that help identify fracture lines, bone displacement, and the stability of the pelvic structure. Magnetic Resonance Imaging (MRI) is also used, especially when an insufficiency fracture is suspected or if there are signs of nerve root involvement. MRI is effective at detecting bone edema, which indicates a fresh stress fracture, and provides superior detail regarding soft tissues and the status of the sacral nerves.
The management plan depends on the fracture’s stability and the presence of neurological deficit.
Non-Surgical Management
Stable, non-displaced fractures, common with insufficiency injuries, are often managed non-surgically using conservative treatment. This approach involves reduced weight-bearing, often with crutches or a walker, and pain control using medication. The goal is to allow the bone to heal naturally while minimizing stress on the fracture site.
Surgical Management
Surgery is generally reserved for unstable fractures, typically those from high-energy trauma, or when there is progressive neurological compromise. Procedures involve internal fixation, where surgeons use screws, rods, or plates to stabilize the fractured segments and realign the pelvic ring. For significant displacement, fixation techniques such as percutaneous iliosacral screws or lumbopelvic fixation are employed to maximize stability. Decompression surgery may be necessary in cases of nerve compression to relieve pressure.
Recovery Timelines and Rehabilitation
Recovery duration varies significantly based on the fracture type and treatment path. For stable fractures managed conservatively, patients may begin to bear weight and see substantial improvement within eight to twelve weeks. Full return to pre-injury activities is typically possible within three to four months.
Severe injuries, such as high-energy trauma requiring surgical fixation, have a substantially extended recovery period, often lasting four to six months or longer. Rehabilitation is a component of recovery, beginning soon after the initial pain subsides. Physical therapy focuses on restoring mobility in the hips and lower back while rebuilding strength in the core and lower extremities. Exercises are tailored to restore a normal gait pattern and prevent residual pain.