{"id":3477,"date":"2020-07-10T02:43:30","date_gmt":"2020-07-10T02:43:30","guid":{"rendered":"https:\/\/vetmed.illinois.edu\/demo-sa-orthopedics\/?page_id=3477"},"modified":"2021-01-25T18:06:34","modified_gmt":"2021-01-25T18:06:34","slug":"fracture-healing","status":"publish","type":"page","link":"https:\/\/vetmed.illinois.edu\/demo-sa-orthopedics\/fracture-healing\/","title":{"rendered":"Fracture Healing"},"content":{"rendered":"

<\/i><\/i><\/span>Healing Overview<\/span><\/a><\/h4><\/div>
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Healing Overview:<\/h3>\n

Fracture healing is modulated by the biological and mechanical environment of the fracture.\u00a0 The biological environment of the fracture determines the speed of bone healing. Provided there is adequate vascularity, the mechanical environment or stability at the fracture determines the pattern of bone healing which can range from direct bone formation to indirect bone union via endochondral ossification.<\/p>\n

Clinical Union is by definition when a fracture has healed sufficiently to safely remove the support without the risk of refracture. Understanding the cellular process occurring with different patterns of bone healing and using that understanding to interpret the corresponding radiographic images is essential for accurate post-operative care.\u00a0 As long as the fracture is not bridged with bone, exercise is controlled and the fixation left in place or, in the case of external fixators, destabilized \u00a0to promote bone formation.\u00a0 Casts or implants allowing callus formation usually have to be removed by 6 weeks which is why they are reserved for rapidly healing fractures<\/p>\n<\/div>\n

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\"Tibula<\/a><\/span><\/div>\n
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Strain<\/h4>\n

Definition and Impact:<\/h5>\n

Motion at the fracture is described by the concept of strain. Strain is calculated by dividing the original width of the fracture by the change in width occurring with motion and is expressed as a percent. The strain environment dictates the type of tissue formed at the fracture. Granulation tissue can form in 100% strain environments. Connective tissue forms in a strain environment of 20%. Fibrocartilage can form in a strain environment of 10%. Bone can only form in a strain environment of 2% or less.<\/p>\n<\/div>

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Fragment Effect on Strain:<\/h5>\n

Multifragment fractures distribute strain across the fracture area, decreasing the strain environment in comparison to single fractures.<\/p>\n<\/div>

\"Fracture<\/a><\/span><\/div>
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Nature\u2019s Way to Minimize Strain:<\/h5>\n

The strain environment is decreased by natural healing processes found in indirect bone healing such as bone resorption at the fracture which widens the original width of the fracture; endochondral ossification where tissues are formed in an orderly pattern according to the strain environment; and periosteal callus formation which increases the diameter of the bone at the fracture site thereby greatly increasing the ability of the bone to resist bending and torsional forces.<\/p>\n<\/div>\n

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Operative Treatment to Minimize Strain:<\/h4>\n

The strain environment is greatly affected by the operative treatment of the fracture. Compression of the fracture with plate or lag screw application results in a very low strain environment. Strain increases with the increasing motion associated with various types of external fixator frames, interlocking nails, and cast application respectively.<\/p>\n<\/div>

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\"clinical<\/p>\n<\/div><\/div><\/div>

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\"Non<\/p>\n<\/div><\/div><\/div>

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<\/i><\/i><\/span>Diaphyseal Bone Healing<\/span><\/a><\/h4><\/div>

Indirect Bone Healing:<\/h4>\n

Indirect bone healing occurs in fractures with a more compliant fixation. Allowing motion at the fracture.<\/p>\n

Press button 1<\/strong>. Remember that the extraosseous blood supply (red vessels extending into the fracture and the growth factors found in the fracture hematoma are paramount for healing. Granulation tissue (blue) which survives in strains up to 100% infiltrates the fracture site first (note the movement at the fracture). This tissue slightly stabilizes the fracture to allow the gradual formation of connective tissue and fibrocartilage (orange) which survive in strains of 20 and 10% respectively, and in turn continue to stabilize the fracture site.<\/p>\n

Press button 2.<\/strong> Bone callus (bone-colored chips) forms first on the relatively stable endosteal and periosteal bone surfaces. These processes continue until the strain environment is less than 2% and mineralization of the fibrocartilage (purple) occurs beginning at the fragment surfaces and moving toward the center of the gap.<\/p>\n

Press button 3.<\/strong> Local resorption of the mineralized tissue is followed by the formation of bridging bone callus.<\/p>\n

Press button 4.<\/strong> Continued formation and resorption of bone at the fracture site results in remodeling of the callus to cortical bone.<\/p>\n

Press button 5.<\/strong> Implants (or casts) are removed when bone bridges the fractures on all radiographic views.<\/p>\n<\/div>

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