Femur intramedullary (IM) nailing is a surgical procedure used to treat fractures of the thigh bone (femur), most commonly fractures of the femoral shaft. Because the femur is the strongest and longest bone in the body, fractures often result from high-energy trauma such as car accidents, falls from height, or severe sports injuries, though they can also occur from lower-energy trauma in older adults with weakened bone. IM nailing is considered the gold standard treatment for most femoral shaft fractures due to its strength, reliability, and ability to support early mobilization. Before surgery, patients typically undergo imaging such as X-rays or CT scans to assess fracture type, alignment, and any associated injuries. The procedure is performed under general or regional anesthesia. During surgery, the surgeon makes a small incision either near the hip (antegrade approach) or near the knee (retrograde approach), depending on the fracture location, patient anatomy, and associated injuries. A metal rod, usually made of titanium, is inserted into the medullary canal (the hollow center of the bone) and passed across the fracture site to hold the bone in proper alignment. Once the nail is positioned, locking screws are placed through the bone and into the nail at both the top and bottom. These screws prevent rotation and shortening of the bone, creating a stable internal construct that allows the femur to heal correctly. In many cases, the canal is gently widened (reamed) before nail insertion to improve fit and stability, though unreamed techniques may be used in certain trauma or medical situations. After surgery, patients are encouraged to begin movement early. Depending on fracture stability and surgeon guidance, partial or full weight-bearing may be allowed soon after the operation. Pain control, physical therapy, and gradual strengthening are key parts of recovery. Most patients remain in the hospital for several days, particularly if the injury occurred as part of major trauma. Bone healing typically occurs over several months, with most patients regaining good function and mobility. Complications are uncommon but can include infection, delayed bone healing, hardware irritation, or blood clots. Overall, femur IM nailing has a high success rate and is highly effective at restoring limb alignment, strength, and function.