Screw osteosynthesis is the process of screwing and bridging broken bones (fractures) with foreign material in the form of screws. The screws used for this purpose are made of surgical steel, titanium, or similar materials.
What is screw osteosynthesis?
Screw osteosynthesis is the screwing and bridging of bone fractures (fractures) with foreign material in the form of screws. This form of osteosynthesis is a commonly used method for internal anatomic refixation of fractures or fracture fragments (fragments). The advantage of this method is that usually only a minimally invasive surgical procedure needs to be performed. In addition, in the case of dislocated fractures (e.g. ankle joint), there is only a slight loss of the joint surface. The aim of screw fixation is to hold the fracture or fracture fragments in place until they have healed. Resulting axial and joint malpositions are corrected during refixation. The advantage to non-surgical (conservative) treatment methods is that the anatomy can be precisely and specifically restored. The fractured area can be quickly exercised, moved and fully loaded depending on the symptoms. In this way, movement restrictions and muscle atrophy can be prevented. Exercise reduces the risk of thrombosis.
Function, effect, and goals
Used predominantly in surgery and orthopedics, screw osteosynthesis is used when conservative treatment is not possible. This is the case when there is an open fracture, for example. The procedure is performed under anesthesia. This can be plexus anesthesia, spinal anesthesia or general anesthesia. The duration of such an operation depends on the degree of injury. The subsequent stay in the hospital is a few days, although the subsequent removal of the material can also be performed on an outpatient basis. Treatment of an open fracture by screw osteosynthesis significantly reduces the risk of subsequent bone or soft tissue inflammation. For fractures of the upper and lower leg, conservative treatment is possible, but osteosynthesis is more appropriate. With internal stabilization, the affected lower extremity is immediately stable for exercise postoperatively. This means that the patient can move and exercise the limb freely. After a few days of exercise, the leg can be fully weight-bearing, depending on the pain level. If a polytrauma, multiple fracture or comminuted fracture occurs, the fracture fragments are repositioned and fixed. In principle, fractures with displaced fracture fragments are treated with screw osteosynthesis. The aim here is always to reposition and fix the displaced fragments and restore any joint functions in their anatomical axis. Screw osteosynthesis is not only used for trauma-related fractures. Other applications include orthopedics. Selectively severed bones are fixed by this procedure for alignment in cases of axial malalignment (e.g., knock knees or bow legs). Furthermore, osteosynthesis is used for arthrodesis (joint stiffening), general instability or instability after tumor removal. However, screw osteosynthesis is also sometimes preferred to plate osteosynthesis for soft tissue injuries. The surgical procedure is as follows:
Once the surgeon has gained access to the fractured area, the fracture fragments are aligned with each other in the correct position. For the actual fixation of the fracture, a distinction is made between cortical screws and cancellous screws. Both are so-called lag screws, these are to pull the fracture site together. The difference is that the cancellous bone screw has a short shaft and is screwed into the epiphyseal area. The operating physician drills out the cortex of the bone so that a cancellous bone screw fits into the hole. A smaller hole is drilled in the opposite fragment, and a special instrument is used to cut a thread for the screw. Now the screw is screwed into the holes, thus pulling the bone piece with the thread against the bone piece with the single hole. By tightening the screw, the fracture fragments are firmly connected to each other. The cortical screw, on the other hand, is screwed into the diaphyseal area. Compared to the cancellous bone screw, this has a long shaft and a short thread at the lower end. Here, too, the surgeon drills a hole in the bone into which the screw is inserted.This is now screwed in so that the thread lies behind the fracture line. As with the cancellous screw, the cortical screw pulls both fracture fragments together and thus fixes them.
Risks, side effects, and hazards
The treatment by screw osteosynthesis is always associated with a surgical procedure. Thus, the risk of infection increases, because a closed fracture thus becomes an open fracture and germs can penetrate, the risk of infection increases. In addition, functional limitations, pain, wound healing disorders, pseudarthrosis, instability and arthrosis may occur. Possible serious complications can include loosening or breaking away of the implant due to material failure. This can cause the fracture fragments to slip and result in deformities or shortened extremities. In order to prevent this, regular follow-up should be performed by the treating surgeon or orthopedist, with control by imaging techniques. Postoperative bleeding and scarring with adhesions can occur, as in any surgical procedure. General risks of anesthesia, especially in elderly patients with poor general condition, such as swallowing difficulties, cardiovascular problems, respiratory disorders, etc. should always be considered. In addition, another surgical procedure must be performed to remove the material. Often the material is not removed in older patients because the bone material usually does not become as strong as before. Otherwise, a so-called refracture can occur. In children, however, the material must be removed promptly after the fracture has healed because the bones are still growing.
