Osteosynthesis: Treatment, Effect & Risks

Osteosynthesis is the name given to a surgical procedure for the treatment of bone fractures. The individual bone fractures are reunited using various tools such as nails, screws, plates and wires.

What is osteosynthesis?

Osteosynthesis is a generic term for various surgical procedures to reunite broken bones. Through the use of various connecting aids, the fractures are stabilized again. The medical term osteosynthesis translates into German as bone joining. It is the generic term for various surgical procedures to reunite broken bones. Through the use of various connecting aids, the fractures are re-stabilized so that they can once again grow together as intended by human anatomy. The goal of osteosynthesis is to reunite bones in their original shape. The fracture site is stabilized and the function of the affected bone is restored until it heals.

Function, effect, and goals

There are several different procedures:

  • Medullary nail osteosynthesis
  • Plate osteosynthesis
  • Screw osteosynthesis
  • Kirschner wire fixation (preferably in children).
  • Tension-belt osteosynthesis
  • External fixator
  • Dynamic hip screw for a fracture near the femur. Not every fracture needs to be treated by osteosynthesis.

Doctors perform osteosynthesis for the following conditions:

  • Fractures of the joints
  • Open fractures with injury to soft tissues and skin
  • Bone fractures involving nerves and blood vessels
  • Fractures of the leg
  • Multiple fractures (multiple bone fractures)
  • In patients who have polytrauma due to life-threatening multiple injuries.
  • In osteoporosis and increased age.
  • In patients who need to be quickly mobilized again (eg athletes).

Human bones are composed of compacta (firm cortex) and cancellous bone (soft inner core). The medullary cavity is located in the large bones, where the bone marrow is located. The bones have a covering of periosteum (bone skin). With increasing age, the bone marrow is replaced by fatty tissue. Before the doctors operate on the fracture, they must restore the affected bones to their correct and original position. In less severe fractures, this reduction can be done without surgery. The doctor returns the bones to their correct position by skillful positioning, and then the fracture is fixed with a strong bandage to prevent the bones from slipping again. In this case, the fracture can heal without surgical intervention. With intramedullary nail osteosynthesis, the surgeon opens the medullary cavity of the affected bone using an awl or wire. A guide wire is placed through this channel and pushed into the marrow cavity via a burr. This procedure expands the medullary cavity and provides it with a long nail that acts as an internal splint in the fractured bone. X-ray checks ensure the correct position of the nail. If necessary, the nail is locked with a transverse pin (locking nail) to prevent displacement in the medullary cavity. Plate osteosynthesis exposes the fracture and provides it with a plate that is anatomically matched to the bone and secured with screws in a way that connects the fragments. Screw osteosynthesis uses lag screws and cancellous screws. The lag screw slides through a hole in the bone cortex after the bone is opened. At the opposite end, a hole of unequal size is drilled and a thread is inserted, which is connected to the lag screw. In this way, the bone fracture is held together. The cancellous bone screw is shaped like a long shaft. Again, the screw is attached through drilled holes behind the fracture by means of a thread. Kirschner wire fixation is suitable for correcting fractures in smaller bones such as the fingers or toes. The Kirschner wire is placed through the bone cortex deep into the cancellous bone, leaving the top end on the outside to be pulled out after the fracture heals. This procedure does not stabilize sufficiently, so the application of a cast or splint is necessary to withstand loads.With tension-belt osteosynthesis, the individual bone fracture pieces are connected by crib wires. They run vertically and parallel through the fracture gap. The outer ends are crossed and provided with a soft wire loop (clerage). The opposite book site is provided with a channel through which the wire loop is looped. The surgeon tightens this tightly to hold the book pieces firmly together and convert the tensile forces that actually pull the individual bone fragments apart into compressive forces. The bone fragments are pushed together. External fixator fixes the bone fracture using an external appliance. The fracture is stabilized by pins on either side of the bone. These are placed through small incisions through the skin on the right and left sides and connected to a metal brace that provides the necessary stability. The dynamic hip screw is used for femoral neck fractures. A screw is placed in the part of the femoral neck closest to the hip joint using a guide wire. The screw is threaded into the femoral head with a short, thick thread. A metal plate is screwed into the upper, outer portion of the femur. The unthreaded end of the screw shaft slides through a tube, allowing the patient’s body weight to redirect the loading pressure and compress the fracture.

Risks, side effects, and hazards

After performing osteosynthesis, the surgeon sutures the muscles in the first step, followed by the connective tissue layers and skin. Osteosynthesis procedures are among the routine procedures, yet complications occasionally cannot be ruled out. In rare cases, tendon adhesion, joint stiffness, distortion of cartilage, muscles, tendons, and nerves, compartment syndrome, failure of fracture to heal or inadequate healing (pseudarthrosis), bone necrosis (death of individual pieces of bone), and infection of bone and periosteum may occur. General surgical risks include bleeding, blood clot formation, nerve injury, local infection formation, anesthetic incidents, allergic reactions to individual substances, and scarring. As soon as the postoperative situation allows, osteosynthesis patients should resume movement as soon as possible; excessive rest is the wrong approach and can lead to complications such as joint stiffness. Physical therapy is the ideal way to return to a normal weight-bearing situation after hospitalization. Because osteosynthesis materials such as screws, wires, and plates are removed in a period of 6 to 24 months for fractures of the arms and shoulders, and 12 to 24 months for fractures of the legs.