Pelvic fixation is a surgical technique used to stabilize the pelvic ring, the foundational structure connecting the spine to the lower limbs. This procedure provides strong, internal support to the bones of the pelvis, sacrum, and ilium. Fixation becomes necessary when the natural stability of this junction is compromised by severe injury or extensive surgical correction. The goal is to rigidly immobilize the area, allowing for bone healing and successful fusion to restore the body’s ability to bear weight and maintain balance.
Conditions Requiring Pelvic Fixation
The need for pelvic fixation arises from two categories: acute, high-energy trauma and chronic, complex spinal instability. High-impact injuries, such as those sustained in motor vehicle accidents or falls, can cause severe pelvic ring disruptions. These injuries are often rotationally and vertically unstable, meaning displaced bone fragments cannot support the body’s weight, necessitating immediate stabilization. Specific indications include a pubic symphysis separation greater than 2.5 centimeters or vertical displacement of the hemipelvis exceeding one centimeter.
Severe sacral fractures, particularly those resulting in spinopelvic dissociation, also require fixation. Spinopelvic dissociation is an unstable condition where the connection between the spine and pelvis is completely severed, often involving nerve damage. Early surgical intervention in acute trauma helps control internal bleeding, reduces pain, and allows for earlier patient mobilization.
The second major indication involves complex reconstructive spinal surgery requiring a long spinal fusion construct. When fusing the spine over many levels and extending instrumentation down to the sacrum, supplementary pelvic fixation is required to prevent failure. The lumbosacral junction is subjected to immense biomechanical forces, and fusing more than three levels above the sacrum creates high stress on this connection point.
This fixation anchors the spinal hardware firmly into the strong iliac bones, bypassing the weak bone quality often found in the sacrum alone. This additional anchoring promotes solid fusion across the lower spine and pelvis. Conditions such as severe adult spinal deformity, high-grade spondylolisthesis, or revision surgery following failed fusions often require this enhanced pelvic support.
Surgical Techniques Used for Stabilization
To achieve rigid pelvic stabilization, surgeons employ structural methods and specialized hardware tailored to the patient’s needs. For acute pelvic ring fractures, internal fixation often uses plates and screws to compress and hold fractured bone segments in their correct anatomical position. External fixation may also be used provisionally in unstable patients to quickly control bleeding and stabilize the pelvis.
S2 Alar Iliac (S2AI) Technique
For spinal reconstruction extending to the pelvis, specialized techniques involve placing long screws into the thickest parts of the iliac bone. One modern, commonly used method is the S2 Alar Iliac (S2AI) technique. This involves inserting a screw near the S1 and S2 foramina on the sacrum, angling it across the sacroiliac joint and deep into the iliac wing.
The S2AI technique offers advantages because the screws are placed more medially and are in line with the spinal rods, eliminating the need for bulky offset connectors. This positioning requires less extensive soft tissue dissection and reduces the risk of hardware causing pain or skin irritation, a common issue with traditional iliac screws. These screws typically range from 65 to 120 millimeters to ensure a strong hold deep into the bone.
The stability created by these long screws allows the bone graft material to successfully fuse the vertebrae and the pelvis. Whether using S2AI or other iliac screws, the hardware functions as an internal brace, holding the construct rigid until the biological fusion process is complete. This mechanical support counteracts the high forces acting on the lumbosacral junction, lowering the risk of hardware failure and non-union.
Navigating Post-Operative Recovery
Recovery from pelvic fixation, especially when combined with a long spinal fusion, is a gradual process that can span up to a full year. Immediately following the procedure, patients remain hospitalized for a few days while pain management is initiated and mobilization is assessed. A structured pain control plan, often including prescribed medications, is a major focus during this early phase to facilitate comfort and movement. Patients are encouraged to begin walking as soon as possible, sometimes on the same day, to promote circulation and prevent complications like blood clots.
The initial weeks at home require strict adherence to activity restrictions, primarily avoiding the “BLT” movements: bending, lifting anything heavier than five to ten pounds, and twisting the torso. These limitations protect the surgical site and the hardware during initial healing. Physical therapy is a cornerstone of long-term recovery and generally begins a few weeks to a few months after surgery, once initial bone healing is progressing well.
Therapy initially focuses on gentle movement and learning safe techniques for performing daily activities without stressing the fusion site. Over the following months, the focus shifts to rebuilding muscle tone and strength. The biological process of bone fusion takes time, with the vertebrae and pelvis continuing to solidify for six to twelve months post-surgery.
While non-strenuous work may be resumed within a few weeks, returning to physically demanding jobs or high-impact sports usually requires waiting until the one-year mark, when the fusion is considered solid. In some instances, the metal hardware may become prominent or cause localized discomfort, requiring a second, smaller surgery for removal.