Home Therapies Osteosynthesis: definition, reasons, procedure

Osteosynthesis: definition, reasons, procedure

by Josephine Andrews
Published: Last Updated on 466 views

Osteosynthesis is a procedure for the surgical treatment of broken bones. The individual fragments are reconnected with various tools such as screws, nails, plates and wires. Read all about the various osteosynthesis procedures, when they are necessary and what risks they entail. 

What is osteosynthesis?

Osteosynthesis (roughly translated: “bone connection”) is the umbrella term for various surgical procedures that are used to treat broken bones. The bone loses its stability as a result of the fracture, and the constant shifting of the fragments means that it cannot heal adequately.

The aim of the osteosynthesis procedure is to bring the individual fragments together in their original form, to stabilize the fracture site and thus restore the function of the bone until it heals. The following procedures are available for osteosynthesis:

  • screw osteosynthesis
  • plate osteosynthesis
  • intramedullary nail osteosynthesis
  • Kirschner wire fixation (especially in children)
  • Tension strap osteosynthesis
  • External fixator
  • Dynamic hip screw (in case of fracture of the femur near the hip)

Which osteosynthesis method is used depends on the location and type of bone fracture. 

When is osteosynthesis performed?

Not all broken bones need to be treated with surgery. However, osteosynthesis is currently recommended for the following clinical pictures:

  • Bone fractures involving a joint Open bone fractures (with injury to skin and soft tissues)
  • Broken bones with damage to blood vessels or nerves
  • broken bones in the leg
  • Bone fractures with multiple fragments (multiple fragment fractures)
  • Bone fractures in patients with multiple, life-threatening injuries (polytrauma)
  • Bone fractures in patients with poor fracture healing (e.g. due to osteoporosis , old age)
  • if patients need to be mobilized again quickly for certain reasons (e.g. competitive athletes)

What do you do with an osteosynthesis?

The human bone consists of a solid bark (compact bone) and a somewhat softer core, the spongiosa. Inside large bones is the medullary cavity, which contains the bone marrow; with age it is increasingly replaced by fat . The bone is covered by the periosteum, the so-called periosteum.

Before the operation

Before the broken bone is treated with osteosynthesis, the pieces of bone must be brought back into their correct position in relation to one another. This process is called reduction. In many cases, the reduction can be closed, ie done without an operation. In this case, the doctor returns the fragments to their original position by skilfully moving and pulling on the broken bone. In complicated cases, the reduction is performed during the operation.

Before attaching to osteosynthesis, the surgeon disinfects the patient’s skin and covers it with sterile towels, sparing the operation area.

screw osteosynthesis

In screw osteosynthesis, a distinction is made between lag screws and cancellous screws. In lag screw osteosynthesis , the doctor drills the cortex of a piece of bone wide enough that a screw can slide into this hole. In the opposite fragment, the doctor drills a slightly smaller hole, in which he cuts a thread for the screw with a special instrument.

If he now turns a screw into the holes, the piece of bone with the thread is pulled against the piece of bone with the sliding hole. By tightening the screw, the fragments are pressed firmly together.

The spongiosa screw has a long shaft with a short thread at the lower end. Here, too, the surgeon drills a hole in the bone in which the shaft of the screw can slide. Now he turns the spongiosa screw into the drill hole so that the thread of the screw is behind the fracture line. According to the same principle as with the tension screw, this creates a tension on the fragments, which then brings them together. 

plate osteosynthesis

In plate osteosynthesis, the surgeon first exposes the broken bone. Then he chooses a plate that fits the bone surface in terms of shape and size. He places this over the fracture line and fixes it to all fragments with screws in the bone. The fragments are firmly connected to one another by the plate.

intramedullary nail osteosynthesis

The surgeon opens the bone’s medullary cavity with a wire or awl. He places a guide wire in this canal, over which a reamer is pushed into the medullary cavity. With this, the doctor widens the marrow cavity of the bone. Now he drives a long nail into the canal in the medullary cavity, which clearly bridges the fracture gap. The long nail is now in the broken bone as an inner splint. All this is done under regular X-ray control to ensure the correct position of the nail and the fragments. If necessary, the surgeon locks the nail in the bone with a transverse bolt (locking nail) so that it cannot move within the medullary cavity.

Kirschner wire fixation

During osteosynthesis using the so-called Kirschner wire, the surgeon bridges the fracture site with one or more elastic steel wires. The wires are buried deep in the cancellous bone through the cortex of the bone, but the upper end remains outside the bone. This allows the surgeon to pull the wire out again after the fracture has healed

The Kirschner wire fixation is suitable for the treatment of fractures of smaller bones (eg fingers) and fractures in the area of ​​​​the growth plates (in young people). It is also used in the collarbone area, usually with several wires in different puncture directions.

Since this form of osteosynthesis does not sufficiently stabilize the fracture for greater mechanical loads, a splint or plaster cast must also be applied.

Tension strap osteosynthesis

Tension band osteosynthesis uses the tensile forces that pull the individual fragments apart and converts them into compressive forces that press the fragments together. To do this, the surgeon first inserts two wires (pinning wires) into the bone so that they run parallel to one another and perpendicularly through the fracture gap. Here, too, the correct position of the wires is checked with an X-ray image.

A soft wire loop (cerclage) is now crossed on the outside around the protruding ends of the wires. A channel is now drilled in the bone on the other side of the fracture line. The wire loop is looped through this and is now taut. The doctor then bends over the protruding ends of the wire so that they securely hold the soft wire loop.

external fixator

This form of osteosynthesis stabilizes (fixes) the bone fracture with an external (external) cradle. First, the surgeon makes small incisions in the patient’s skin along the broken bone. Through these he drills holes in the bones, into which he inserts long, solid metal rods, the so-called pins. These are – usually on both sides of the break – connected to a metal strut on the outside and thus stabilized.

Dynamic hip screw

This osteosynthesis is used for fractures of the femoral neck. To do this, the surgeon inserts a guide wire into the part of the femoral neck near the hip joint under X-ray control. Using this, he now turns a screw with a short, thick thread into the femoral head.

He now screws a metal plate with a tubular receptacle into which the unthreaded part of the screw shaft can slide to the upper outer side of the femur. The patient’s body weight now deflects the load in such a way that the fracture gap is compressed.

After the operation

After the osteosynthesis has been introduced, the doctor sews up muscles, layers of connective tissue and skin one after the other and applies a wound dressing. The patient can recover from the anesthetic and the operation in the recovery room.

What are the risks of osteosynthesis?

Although the various osteosynthesis procedures are standard interventions in the treatment of broken bones, problems can arise. These can be:

  • joint stiffening
  • tendon adhesion
  • Atrophy of muscles, ligaments, and cartilage from inactivity
  • compartment syndrome
  • fat clot formation
  • non-healing fracture with formation of a false joint (pseudarthrosis)
  • death of a piece of bone (bone necrosis)
  • Infections of the periosteum or bone

In addition, the osteosynthesis material can loosen, which makes the fracture unstable. This can cause the fragments to shift again, which may necessitate another operation.

In general, almost every operation carries the following risks:

  • Bleeding during or after surgery
  • blood clot formation
  • Bruising with possible need for surgical evacuation
  • injury to nerves
  • Infection of the surgical site
  • unaesthetic scarring
  • anesthetic incidents
  • allergic reaction to materials used (latex, medication)

What do I have to consider after osteosynthesis?

In order to prevent stiffening of the joint, you should start physiotherapeutic exercises as soon as possible after the operation – provided that the osteosynthesis procedure allows this. Above all, make sure that the joints that are in the vicinity of the fracture and have not been immobilized by the osteosynthesis are regularly moved.

When you can fully load the bone again after osteosynthesis depends on the type of fracture and the chosen osteosynthesis method as well as your individual healing process. Talk to your doctor about the extent to which you can put stress on your bones in everyday life and how your care will be guaranteed after you are discharged from the hospital.

The osteosynthesis material (wires, plates, screws, etc.) can usually be removed again after 6 to 24 months in the case of injuries to the arms and shoulders, and after 12 to 24 months in the case of osteosynthesis following fractures in the legs. 

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