When we suffer a broken bone, we often get told to keep weight off it…. protect it…. 6 weeks until normality resumes…….. But what actually happens?
So in this blog we are going to explain:
1) What happens when you fracture a bone?
2) How do fractures happen?
3) What are the clinical features of a broken bone?
4) What are the types of fractures?
5) How does the bone heal?
6) How do I know when the bone is healed?
What happens when you fracture a bone?
A fracture is a discontinuity in a bone resulting from mechanical forces that exceed the bone’s ability to withstand them.
How do fractures happen?
Fractures can occur in a variety of methods:
- A normal bone subjected to an acute overwhelming force such as a fall on an outstretched arm resulting in a fractured wrist.
- Pathological fractures – a weakened bone from a focal lesion (e.g. metastasis, or bone cyst).
- Weakened bone due to metabolic abnormalities (e.g. osteoporosis) or less frequently, genetic abnormalities (insufficiency fractures).
- Chronic abnormal stresses (e.g. running), resulting in microfractures and eventually, macroscopic failure (fatigue fractures).
- Insufficency and fatigue fractures are usually grouped as “stress fractures”
What are the clinical features of a broken bone?
Clinical features of fractures can vary depending on the cause of the injury and the nature of the fracture. The common signs and symptoms include:
- Pain
- Deformity
- Oedema (swelling)
- Loss of Function
- Muscle Spasm
- Muscle Atrophy
- Abnormal Movement
- Limitation in Joint Range of Motion
- Shock
What are the types of fractures?
There are many types of fractures and the nature of each fracture will result in how treatment is carried out.
- Complete: Extends all the way across the bone (most common)
- Incomplete: does not cross the bone completely (usually encountered in children)
- Non-Displaced / Stable: Fractured ends of the bone line up
- Displaced / Unstable: Fractured portions of bone are separated or misaligned.
- Closed / Simple: Bone does not pierce the skin
- Open / Compound: Skin has been pierced or punctured by the bone or by a blow that breaks the skin at the time of the fracture. The bone or may not be visible.
- Transverse: Fracture is in a straight line across or perpendicular to axis of the bone
- Oblique: Fracture is orientated obliquely across the bone
- Spiral: Fracture spirals around the bone, or a helical fracture path usually in the diaphysis of long bones, common in twisting injuries.
- Stress: Small crack or severe bruising within a bone
- Comminuted: Fracture is in three or more pieces with fragments present at the site
- Compression: Bone is crushed causing the fractured bone to be wider or flatter in appearance
- Segmental: Same bone is fractured in two places so there is ‘floating’ segment of bone
- Bowing: Incomplete fracture of long bone in infants/children due to forces in the axial load.
- Buckle Fracture: Due to direct axial load, the cortex is buckled, often in the distal radius
- Greenstick Fracture: Fracture in a young, soft bone in which the bone bends and the cortex is broken, but only on one side
How does the bone heal?
There are 3 stages to bone healing:
- Inflammatory stage
- Reparative stage
- Remodelling stage
The inflammatory stage
Immediately after the fracture, the space between the bone is filled with blood forming a haematoma. This stops additional bleeding and helps provide structure and support for the important healing inflammatory cells (including cytokines and prostaglandins).
The fibroblasts, chondroblasts and the ingrowth of capillaries is then infiltrated by fibrovascular tissue. This forms a matrix for bone formation and primary callus.
Phase 1 takes approximately a week, forming a primary callus which is non-mineralised and is not visible on x-rays.
Reparative stage
Over the next few weeks, the activation of osteoprogenitor cells (cells which lay down woven bone stabilising the fracture site) transform the primary callus to a bony callus.
Taking several weeks, soft bony callus is remodelled into hard callus. The soft callus is plastic and can easily deform or bend if the fracture is not adequately supported.
This process takes roughly 6 weeks and is why we use this time frame as a marker for a gradual return to activity. Hard callus is weaker than normal bone but is better at withstanding external forces and equates to the stage of “clinical union”, i.e. the fracture is not tender to palpate or with movement.
This can be seen on radiographs within 7-10 days after injury.
Remodelling phase
This phase can take from months to years after the fracture. This phase represents the gradual formation of compact bone with greater biomechanical properties allowing a reduction of the width of the callus.
During remodelling, the healed fracture and surrounding callus responds to activity, external forces, functional demands and growth. Bone (external callus) which is no longer needed is removed and the fracture site is smoothened and sculpted.
Remodelling can result in almost perfect healing, however, where the alignment of the fracture site is not perfect, a residual deformity may remain.
How do I know when the bone is healed?
As mentioned previously, the average time for bone healing is 6-8 weeks but the recovery can take longer.
A fracture is considered to be healed based using the combination of physical findings and symptoms. The following suggest complete healing :
- No pain on weight-bearing, lifting or movement
- No tenderness on palpation at the fracture site
- Blurring or disappearance of the fracture line on X-ray
- Full or near to full functional ability.
However, fracture healing times can depend on many factors.
Local Factors
- The type of fracture, severity and extent of the misalignment of the fractured bone.
- Infections that can lead to delayed, poor, or non-union healing.
- The blood supply to the fractured bone.
- The type of fixation (cast, splint, ORIF procedure, etc).
Systemic Factors
- Age (individuals with osteoporosis are predisposed to further healing complications).
- Nutritional status.
- Smoking (delayed healing)
- The treatment undergone.
If you have suffered a fracture and would like support returning to your normal activities then either book your initial appointment or if you would like to speak to a physiotherapy to discuss your fracture then complete this form.
