Spinal Instability

What spinal instability is

Symptoms in the lumbar spine — low back pain, sometimes with sciatica radiating down the leg — may prompt imaging of the lower back (MRI, CT, or flexion-extension radiographs). In some cases these studies reveal spinal instability: excessive movement or displacement of the vertebrae, or fractures that compromise their normal stability and mobility.

Fusion is not the answer for everyone

Very often, on the basis of instability seen on imaging, surgeons propose spinal fusion — the use of implants such as screws, rods, plates, and grafts to stabilize the spine and, ultimately, reduce the patient’s symptoms.

Performed indiscriminately, or in the wrong patients, this operation has low efficacy: satisfaction rates may fall below 50%. With proper patient selection, those rates are substantially higher.

Two problems arise in everyday practice and make correct selection difficult.

Establishing that instability truly exists. Many doctors, on seeing a minor vertebral displacement or a simple fracture, will present fusion to the patient as a necessity. Instability must first genuinely exist and, second, be severe enough to justify the operation. A very small vertebral shift or a minor fracture rarely produces true instability. A large displacement, or a fracture causing significant deformity, may well establish actual or impending instability — but for lesser injuries, flexion-extension radiographs are essential: films taken with the spine in different positions, to determine whether the vertebrae actually move and to how what extent. Only if significant instability is confirmed does fusion enter the discussion. Too often these studies are never performed, and instability is claimed without being readily demonstrated.

Knowing the real success rates. With indiscriminate fusion or poor patient selection, clinical efficacy falls below 50%. Even with careful selection, clinical success does not exceed 70–80%. Yet 70% in a patient with genuine instability and severe symptoms can be a meaningful outcome.

Who is the right candidate?

The right candidate for fusion must be assessed very carefully, both clinically and radiologically. Clearly suitable are patients with neurological weakness and concomitant instability demonstrably causing their symptoms; patients with significant displacement of the bony structures that in itself constitutes impending instability; and patients with instability confirmed on flexion-extension radiographs — provided the instability is clearly linked to their symptoms and they are otherwise good surgical candidates.

In every case, the instability must be properly established and its causal link to the symptoms clearly defined. The patient should be told the true — not the inflated — success rates, and should choose surgery in full awareness of the risks and possible complications. That choice is justified only when we are confident that fusion offers better results than the alternatives, and when it is genuinely in the patient’s interest.

Careful, evidence-based selection for every patient. Dr. Blionas applies a rigorous, individualized treatment-selection process supported by advanced AI through the Personalized Evidence-Based Treatment Analysis, drawing on both the patient’s own characteristics and the most recent, validated scientific evidence.