Giuseppe Bonaldi
In 2007 we started treating, by means of percutaneous deployment of an interspinous spacer (ISS), patients with intermittent neurogenic claudication (INC) due to segmental stenosis of the lumbar spinal canal. We were globally satisfied with the clinical results, even for elderly patients, for whom a more invasive surgical alternative was more theoretic than practically feasible. However, with disappointment, we observed in a few elderly and/or osteoporotic patients a recurrence of INC symptoms a few weeks after the intervention, due to a subsidence/fracture of bone of the spinous processes. As interventional radiologists, we had a tool in our hands to strengthen bone, polymethylmethacrylate (PMMA). A favorable biomechanical rationale based on a finite elements analysis of ours, confirming data from a cadaveric study,1 fostered the design of a study, entailing injection of PMMA in the spinous processes prior to ISS deployment in patients at risk for fragility fractures. Patients were recruited until statistical analysis showed evidence of safety and efficacy of the technique to prevent delayed fractures of the posterior arch elements. After completion of the study we have on a regular basis applied the technique to “fragile” patients, and we have no longer observed recurrences of symptoms related to fractures or subsidence of spinous processes. Actually, in our own experience, spinoplasty is so simple, quick, safe, and cheap that we extended indications to younger and younger patients, well below the age of 75 set as a limit for recruitment in the study. After all, patients grow old, and we, and they, expect the outcomes (on a clinical and anatomic basis) of interventions to last as long as possible—ideally lifelong. For the same reason, should strengthening of bone be used also in young patients, when some kind of mechanical stress is applied to the bone itself, with the aim of a longer-lasting effect and prevention of time-related wear of bone?