Effect of Tobacco Heating System (THS) on Closed Lower Limb Fracture Healing

Inclusion Criteria: * Closed tibia or femur fracture (according to AO/OTA: 41A2-41C3, 42A-C, 43A-C, 32A-C, 33A2-3, 33B-C) which is surgically treated within 14 days after the trauma at the BG trauma clinic Tübingen. Additional inclusion criteria for the smoking and THS groups: * Smokers with 10-20 packyears smoking history. * Smoking history \>10 years. * Decision not to participate in the free smoking cessation seminars. Exclusion Criteria: * Legal guardian or loss of capacity to consent. * Refusal to participate in the study. * Open fractures or concomitant injuries or complications requiring surgery existing at the time of surgical indication. * Initial surgical treatment of the fracture has occurred ex domo. * No initial surgical treatment within 14 days of sustained trauma. * Using nicotine delivery electronic devices. * Pre-existing autoimmune, immunological, bone or malignant diseases. * Pregnant, breastfeeding and women of childbearing age with existing desire to have children. * History of alcohol abuse or drug abuse. * Taking antioxidants approval by the German Federal Institute for Drugs and Medical Devices (BfArM). * Taking drugs with known effect on bone metabolism (according to Institute for medical and pharmaceutical examination issues (IMPP): allosteric CaSR modulators, bisphosphonates, calcium release inhibitors, alkaline earth ions, RANKL inhibitors, calcitriol, colecalciferol).