Severe old lumbar fractures and dislocations with associated cauda equina nerve transection are rare clinical presentations which pose significant management challenges. This case report highlights a unique instance of such an injury, emphasizing novel surgical strategies for reconstruction and recovery. A 30-year-old male patient was admitted after sustaining a severe open fracture and degree IV posterior dislocation of L3 vertebra, accompanied by cauda equina nerve transection, spinal cord injury and multiple organ injuries. Following initial stabilization, the patient underwent surgical reduction and internal fixation two months after the injury. The procedure involved cauda equina nerve reconstruction using sural nerve grafts. Postoperatively, the patient showed improved bladder function and regained some mobility. However, he later developed arachnoiditis ossificans of the cauda equina, resulting in severe pain, which required additional surgical intervention. In conclusion, this case underscores the importance of timely intervention in severe thoracolumbar injuries and presents a successful approach to nerve reconstruction.