Degenerative pathologies of the spine affect a large proportion of the increasingly ageing population, and are a major public health issue. When conservative treatments (physiotherapy, analgesics, infiltrations) fail, surgical treatment is preferred. Traditionally, a simple lumbar recalibration operation is preferred (bilateral laminectomy decompression), but this may affect spinal stability. In cases of spondylolisthesis or preoperative instability, lumbar fusion (arthrodesis) is sometimes necessary to avoid the risk of major instability, but such an operation is not without risk and may require repeat surgery. The development of new surgical techniques such as uni or bilateral laminotomies, which are less radical, has made it possible to avoid some arthrodeses. Nowadays, the emergence of new surgical techniques such as endoscopy has further reduced the risk of destabilization (shorter post-operative convalescence, less atrophy of the paraspinal muscles) and improved surgeon comfort (better vision and easier instrument handling). Unilateral biportal endoscopy (UBE) is one of two endoscopic techniques and has proven its effectiveness for lumbar decompression in terms of clinical benefits. However, there is no scientific evidence on spinal stability after recalibration under UBE. We believe that minimizing invasiveness with UBE during simple lumbar recalibration surgery can preserve spinal stability, thereby reducing the need for lumbar fixation and lowering the cost of care. We therefore propose to study the maintenance of spinal stability using dynamic radiography at 3 months post-operatively in patients undergoing lumbar recalibration surgery with UBE.