A wedge deformity is a specific type of vertebral compression fracture where the bone collapses unevenly. It primarily affects the vertebral body, the large, cylindrical front part of a spine bone. The characteristic “wedge” shape forms because the anterior (front) height of the vertebra decreases while the posterior (back) height remains relatively intact. This differential collapse changes the normally rectangular vertebral body into a triangular or trapezoidal shape, often resulting from underlying conditions that weaken the bone structure.
How Vertebral Structure Fails
The failure of the vertebral structure is predominantly linked to osteoporosis, the progressive loss of bone density. This condition compromises the internal lattice-like scaffolding, called trabecular bone, which absorbs compressive forces. When the trabecular bone weakens, the vertebra can no longer withstand normal pressure, leading to a fracture even from minor stresses.
In patients with severe osteoporosis, low-energy events like coughing, sneezing, or bending over can generate enough force to cause the anterior column to buckle. The vertebral body’s microarchitecture naturally has a greater density of supporting trabeculae toward the back than the front, predisposing the anterior section to collapse first. This structural bias, combined with the normal forward curvature of the spine, concentrates the compressive load on the front of the vertebra, creating the classic wedge shape.
While osteoporosis is the most frequent cause, a wedge deformity can also result from high-impact trauma, such as a severe fall or a car accident. In these cases, the force applied exceeds the structural limits of even a healthy bone. A key distinction of a wedge fracture is that the posterior wall remains stable, which is important for determining overall spinal stability. Less common causes include metastatic tumors or infection, which pathologically soften the bone.
Identifying the Deformity and Diagnostic Imaging
A wedge deformity often presents with the sudden onset of sharp or stabbing back pain. This pain is typically localized to the fractured vertebra and is aggravated by standing, walking, or any movement that loads the spine. However, a significant number of these fractures, estimated to be up to two-thirds, can be asymptomatic or cause only mild discomfort often attributed to normal aging.
Over time, multiple wedge fractures can lead to noticeable physical changes, including gradual height loss and the development of kyphosis, an exaggerated forward rounding of the upper back. This postural change, sometimes called a “dowager’s hump,” occurs because the series of anterior collapses tilts the spine forward. For definitive diagnosis, medical professionals rely heavily on imaging studies.
Lateral spinal X-rays are the initial tool used to confirm the presence of a wedge deformity and measure height loss. A fracture is generally diagnosed with a height reduction of at least 15 to 20 percent. Computed Tomography (CT) scans offer a detailed view of the bone’s internal structure, assessing the fracture pattern and determining posterior wall involvement for surgical planning. Magnetic Resonance Imaging (MRI) is essential for evaluating soft tissues, such as the spinal cord and nerves, and for determining the acuity of the fracture by looking for bone marrow edema, which indicates a recent injury.
Treatment Approaches for Stabilization
Management of a wedge deformity typically begins with a conservative approach focused on pain control and limiting spinal movement to allow healing. Initial treatment includes a period of rest, though prolonged bed rest is discouraged due to the risk of muscle weakness and further bone density loss. Pain relief is managed with anti-inflammatory medications or analgesics, helping the patient tolerate movement and participate in rehabilitation.
External bracing may be prescribed to provide mechanical support, restricting motion at the fracture site and reducing pain. If pain remains severe and does not respond to conservative care, or if the fracture is unstable, minimally invasive procedures known as vertebral augmentation may be considered. These interventions stabilize the fracture and provide rapid pain relief.
Vertebroplasty involves injecting a specialized bone cement, usually polymethylmethacrylate, directly into the collapsed vertebral body under fluoroscopic guidance. The cement hardens quickly, stabilizing the fractured fragments and preventing painful motion.
Kyphoplasty is a refinement where a balloon is first inserted into the fractured vertebra and inflated to create a cavity. This procedure attempts to restore some lost vertebral height before the cement is injected. By restoring height, kyphoplasty aims to correct the exaggerated spinal curvature and may reduce the risk of future fractures in adjacent vertebrae. Following stabilization, physical therapy is initiated to strengthen surrounding musculature, improve posture, and regain full functional mobility.