The aging spine: clinical instability.

Clinical instability of the spine is an intensely controversial subject, and its diagnosis, especially in the aging, is difficult. Yet success in its management rests on accurate diagnosis. Because both clinical presentation and radiographic manifestations are nonspecific, the diagnosis of clinical instability lies in understanding the biomechanics involved, in recognizing the relevant radiographic manifestations, and, most importantly, in correlating those observations with the patient's clinical history and physical examination. Stabilization is the treatment of choice for clinical instability. Strengthening of the dynamic stabilizers, especially early in the course of the disease, may prevent or alleviate the incapacitating symptoms of instability, and further research into this area should be undertaken. Static stabilization by bracing has not proved effective, and spinal fusion carries a high risk of complication. Fusion should be reserved for patients whose diagnosis is clear and whose symptoms are recalcitrant to conservative management. Further understanding of clinical spinal instability in the aging will require more precise definition of terms and better standardization of criteria for its diagnosis, management, and research.