Some patients with lumbar spine pain are not helped by muscle relaxation and strengthening, or even by taking opiates in the long term. In such cases, an operation is performed to fuse the adjacent vertebrae with a metal structure, which, however, is only effective for a few years. To clarify the reasons for this, Bernhard Weisse from the Swiss Federal Laboratories for Material Science and Technology (Empa) in Zurich and colleagues analysed data from dozens of patients with lower back pain using a computer programme to simulate the human skeleton.

As reported on the institution's website, for some people, bending forward to pick up an object increases the stresses on the intervertebral joints by a third. When a patient develops a disc rupture and undergoes the above-described surgery, this strain is 45 per cent greater than that of a healthy person. The dissemination of this type of computer analysis may facilitate the decision as to whether a fusion of adjacent vertebrae should be performed on a given patient.