Pseudoarthrosis
Pseudoarthrosis, also known as a nonunion, occurs when bone does not heal or fuse as expected. In the spine, pseudoarthrosis most commonly refers to a failed or incomplete fusion following spinal fusion surgery. When the intended fusion does not become solid, persistent motion at the surgical level may contribute to ongoing pain and reduced spinal stability.
What Is Pseudoarthrosis?
Bone healing requires enough stability, blood supply and healthy bone formation for separate pieces of bone to join together. Pseudoarthrosis occurs when that process does not successfully complete. In spinal fusion patients, the vertebrae remain incompletely fused despite undergoing surgery intended to permanently join them.
A Fusion That Doesn't Fully Heal
After spinal fusion surgery, bone is expected to gradually grow across the treated level and form a solid bridge between the vertebrae. When this does not occur, small amounts of continued movement may remain at the fusion site and can contribute to persistent or recurrent symptoms.
How Spinal Pseudoarthrosis May Feel
Some nonunions produce few symptoms, while others can cause significant pain or recurrent symptoms following spinal fusion.
Possible Symptoms May Include:
What Does the Body Need for a Successful Fusion?
Several biological and mechanical factors work together to allow bone to heal and form a solid fusion.
Stability
Excessive movement between bone surfaces can interfere with formation of a solid fusion. Surgical instrumentation is often used to stabilize the area while new bone develops.
Blood Supply
Healthy circulation delivers oxygen, nutrients and cells needed for bone formation. Poor vascular supply can impair the healing process.
Nutrition
Adequate protein, calories, vitamins and minerals are important for bone healing and overall recovery after surgery.
Bone Formation
The body must generate enough healthy new bone to bridge the treated vertebrae and create a durable fusion.
What Can Increase the Risk of Pseudoarthrosis?
Some factors can interfere with normal bone formation or reduce the likelihood that a spinal fusion will become fully solid.
Smoking & Nicotine Use
Nicotine can reduce blood flow and interfere with bone-forming cells, making smoking and other nicotine use important risk factors for spinal nonunion.
Diabetes
Diabetes can affect circulation and tissue healing and may increase the risk of delayed or incomplete bone fusion.
Bone Health & Age
Poor bone quality, osteoporosis and other age-related factors can make successful bone healing more challenging.
Complex or Multi-Level Fusion
Larger spinal fusions and more complex procedures may require greater amounts of bone healing and can have a higher risk of nonunion.
How Pseudoarthrosis Is Diagnosed
Persistent pain after spinal fusion does not automatically mean pseudoarthrosis. Imaging and clinical evaluation are used to determine whether a solid fusion has formed and whether a nonunion is actually responsible for the symptoms.
The original diagnosis, levels fused, surgical technique and recovery following the procedure are reviewed.
Spinal movement, tenderness, strength, sensation and other neurological findings may be evaluated.
Standard or flexion-extension X-rays may help identify abnormal movement or changes involving surgical hardware.
CT scans can provide detailed views of bone formation and are often useful when evaluating whether a spinal fusion is solid.
Treating Pseudoarthrosis
Treatment depends on the severity of symptoms, spinal stability, neurological findings and whether the nonunion is clearly responsible for the patient's pain.
Conservative Care
Some patients can be managed with activity modification, physical therapy and other conservative approaches when the spine remains stable and symptoms are manageable.
Pain Management
Medication and targeted interventional procedures may be used to manage symptoms when appropriate, particularly when another pain generator is also present.
Optimize Bone Healing
Smoking cessation, adequate nutrition and management of medical conditions that affect bone healing may be important components of the overall treatment strategy.
Revision Surgery
Symptomatic or unstable pseudoarthrosis may require revision fusion surgery, sometimes involving additional bone grafting, replacement or reinforcement of hardware and improved stabilization.
A Nonunion Can Be One Cause — But It Isn't the Only Possibility.
Patients can experience pain after spinal fusion for many reasons, including nerve irritation, adjacent segment degeneration, facet or sacroiliac joint pain, hardware problems and pseudoarthrosis. Determining whether the fusion has actually failed to heal — and whether that nonunion is responsible for the symptoms — is an important step before deciding on additional treatment.
Still Experiencing Pain After Spinal Fusion?
Schedule a consultation to evaluate persistent post-surgical pain and determine whether pseudoarthrosis or another condition may be contributing to your symptoms.