Broken bones have always been challenging to manage due to the severity of the acute disability, the level of the pain and the functionally important negative consequences which can ensue, ensuring fracture treatment an important place in medical care. Fracture treatments have included amputation, immobilisation, replacement, internal fixation and traction. Infection is and was a significant risk in open fractures which might have important soft tissue damage, typically managed in the past by amputation. The surgeon who developed immunisation, Lister, promoted the concept of openly reducing and internally fixing patellar fractures.
Fixing bone fractures moved forward in the 1880s and 1890s by the introduction of wires, screws and plates but their effectiveness was compromised by allergy to metal, infections, implant structure and a lack of knowledge about the natural processes of fracture healing. In the 1950s the fixation of bone fractures was improved by clear technical guidelines and principles of bone fracture fixation, with this developing into the modern management of fractures.
The blood supplies through the solid bone and that through the surrounding membrane are both disrupted by a fracture and good fracture healing depends on having an adequate blood supply. Inflammation, soft callus, hard callus and remodelling are the four stages of bone fracture repair and a fracture exhibits the cardinal signs of inflammation which include redness, swelling, pain and heat. When a bone fractures the area bleeds and collects as a haematoma at the site. New blood vessels form and cells multiply secondary to immigration of inflammatory cells.
The Repair Biology of Fractured Bone
The haematoma around the site of the fracture attracts chondroblasts, cells which manufacture cartilage, and the fracture area becomes invaded by fibrous tissue. This increases the stability of the blood clot at the fracture and starts the progress towards stiffening. The soft callus which forms initially is then converted into hard bone via the hard callus phase by cartilage gradually becoming bone and bone forming below the membrane covering the bone. Once a more solid connection develops between the fragments the fracture is rated as united, after which time it gradually develops into lacunar or mature bone via a remodelling process.
As the fibrous bone is being converted into lamellar bone this process is known as secondary bone union or indirect fracture repair, the natural method which fractures heal. Callus formation with this secondary healing occurs where the bone is somewhat displaced and not rigidly fixed. If the fracture is reduced, meaning restored to a close fitting state like before the fracture, and internally fixed this alters the healing biology of the bone. Making a close fit of the fracture and stabilising it very strongly changes the way the fracture behaves by removing physical stresses and if very close and very stable the bone may heal directly across the fracture without the callus stages. Bone building cells cross the gap and the small gaps left are filled in provided no excessive strain is applied to the site. This is called direct bone healing or primary bone union.
The surgeon's decisions about which form of internal fixation to use for a particular fracture determines the method of fracture healing which occurs at the operated site. If a high level of stability is provided, with little or no movement at the fracture, then primary or direct bone healing will occur with remodelling. If a lower degree of stability and more potential movement is present at the fracture the healing will be secondary or indirect bone repair.
Fixation with Pins and Wires
Fractures are fixed by a variety of devices which include pins, wires, nails, plates and screws, depending on the location and severity of the fracture and the type of fixation provided. Pins and wires are the simplest methods of fracture fixation and the commonest ones are named after the people who developed them. Kirschner or K-wires are narrow wires varying in diameter from 0.6 to 3.0 millimetres and Steinmann pins vary from 3 to 6 millimetres in diameter. K-wires are not stiff and can be easily bent as a typical wire can, so they are mostly an addition to other methods of fracture stabilisation. These techniques can initially fix a fracture in preparation for more definitive techniques later, with minimal soft tissue and bone damage occurring. - 14130
Fixing bone fractures moved forward in the 1880s and 1890s by the introduction of wires, screws and plates but their effectiveness was compromised by allergy to metal, infections, implant structure and a lack of knowledge about the natural processes of fracture healing. In the 1950s the fixation of bone fractures was improved by clear technical guidelines and principles of bone fracture fixation, with this developing into the modern management of fractures.
The blood supplies through the solid bone and that through the surrounding membrane are both disrupted by a fracture and good fracture healing depends on having an adequate blood supply. Inflammation, soft callus, hard callus and remodelling are the four stages of bone fracture repair and a fracture exhibits the cardinal signs of inflammation which include redness, swelling, pain and heat. When a bone fractures the area bleeds and collects as a haematoma at the site. New blood vessels form and cells multiply secondary to immigration of inflammatory cells.
The Repair Biology of Fractured Bone
The haematoma around the site of the fracture attracts chondroblasts, cells which manufacture cartilage, and the fracture area becomes invaded by fibrous tissue. This increases the stability of the blood clot at the fracture and starts the progress towards stiffening. The soft callus which forms initially is then converted into hard bone via the hard callus phase by cartilage gradually becoming bone and bone forming below the membrane covering the bone. Once a more solid connection develops between the fragments the fracture is rated as united, after which time it gradually develops into lacunar or mature bone via a remodelling process.
As the fibrous bone is being converted into lamellar bone this process is known as secondary bone union or indirect fracture repair, the natural method which fractures heal. Callus formation with this secondary healing occurs where the bone is somewhat displaced and not rigidly fixed. If the fracture is reduced, meaning restored to a close fitting state like before the fracture, and internally fixed this alters the healing biology of the bone. Making a close fit of the fracture and stabilising it very strongly changes the way the fracture behaves by removing physical stresses and if very close and very stable the bone may heal directly across the fracture without the callus stages. Bone building cells cross the gap and the small gaps left are filled in provided no excessive strain is applied to the site. This is called direct bone healing or primary bone union.
The surgeon's decisions about which form of internal fixation to use for a particular fracture determines the method of fracture healing which occurs at the operated site. If a high level of stability is provided, with little or no movement at the fracture, then primary or direct bone healing will occur with remodelling. If a lower degree of stability and more potential movement is present at the fracture the healing will be secondary or indirect bone repair.
Fixation with Pins and Wires
Fractures are fixed by a variety of devices which include pins, wires, nails, plates and screws, depending on the location and severity of the fracture and the type of fixation provided. Pins and wires are the simplest methods of fracture fixation and the commonest ones are named after the people who developed them. Kirschner or K-wires are narrow wires varying in diameter from 0.6 to 3.0 millimetres and Steinmann pins vary from 3 to 6 millimetres in diameter. K-wires are not stiff and can be easily bent as a typical wire can, so they are mostly an addition to other methods of fracture stabilisation. These techniques can initially fix a fracture in preparation for more definitive techniques later, with minimal soft tissue and bone damage occurring. - 14130
About the Author:
Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about Physiotherapists, physiotherapy, Physiotherapists in Coventry, back pain, orthopaedic conditions, neck pain and injury management. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK
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