If the lumbar region is suddenly painful and cannot be bent, the following causes are common: First, lumbar muscle sprain: in the process of strenuous exercise, acute sprain of the lumbar muscles can occur due to rotational movements, and the patient will suddenly feel pain and cannot bend, and there will be obvious painful symptoms when pressing or tapping the lumbar muscles, and after braking and resting, the clinical symptoms can be significantly relieved. Second, lumbar small joint dislocation: it may occur when the patient is moving around, which will lead to lumbar joint aliquot symptoms, suddenly causing lumbar pain, and cannot bend, the lumbar spine is easy to maintain a fixed posture, taking X-ray film can confirm the diagnosis of lumbar small joint dislocation. Timely treatment with manipulation reset and traction can lead to rapid improvement of clinical symptoms. If there is sudden pain in the lumbar region and inability to bend the back, treatment should be given as early as possible.