Why Do Bones Hurt As They Heal?

Injury and bone fracture are painful conditions when suddenly tissues, vessels, and nerves are ruptured and bones are broken. It is not a surprise to have sharp pain for a few days after trauma; however, the pain can last even longer, weeks or even months after injury. Let's discuss more about why do bones hurt as they heal, and what causes the sub-acute and chronic pain conditions.

The pain is a normal process during a bone fracture that begins at the beginning of the trauma and continues through the healing process. However, the perception of the pain should decrease later on as the bone heals. It is interesting to mention that pain can last a month; however, this is a consequence of non-union or other conditions.

The healing time and factors

The healing of the fractured bone lasts for six weeks though it might take a longer period that mostly depends on a few factors:

• Fractured bone. The smaller bones heal faster than the big ones.
• Age. The younger population has advantages in bone healing compared with the elderly. When we age, the immune system response is lower, which is why it affects the inflammatory response during fracture healing.
  
• Smoking. Affects callus formation. Nicotine forms weak bony calluses and delays the healing process.
• Diabetes. Prolongs the healing process of the fracture because of delayed ossification.
• Malnutrition. Calcium deficiency as well as vitamin D are the compromising factors in the bone healing process.
• Non-union. The fractured area prolongs the healing process and previously mentioned factors such as age, smoking, diabetes, and malnutrition together with infection, blood supply, and fracture characteristics are the reasons for the non-union of the bone. Non-union of the fractured bone consists of 2 to 10% of all fractures.

What are the stages of bone healing and why does it hurt?

There are three main stages of bone healing that connect together with the three stages of pain.

Acute pain/inflammation phase

During the acute pain phase, the hematoma is formed because many blood vessels are ruptured, and acute inflammation starts. This lasts for 24-48 hours, and it is complete after 7 days. As we know, inflammation is a protective response that has the major task of removing harmful stimuli.

During this procedure, all of the protective soldiers of our body: macrophages, dendritic cells, lymphocytes, fibroblasts, and many others—recognize invading enemies and start to fight with them. Besides, many blood vessels start to dilate. The fractured site starts to show redness, heat, pain, and loss of function.

The fractured area must be immobilized. Try not to use the injured part of the body; otherwise, the pain will remind you about it. However, a few days after the trauma happened, in a resting position, the acute pain should start to pass, and if the pain is not getting better, there might be a possibility that the fractured area is not healing properly. If you have any doubts, contact your healthcare provider.

Repair/sub-acute pain phase

During the repair phase, the soft bony callus formation starts. At the end of the repair, phase a hard callus of immature bone forms.

This can be taken from the end of the inflammation phase to 4-6 weeks. The newly formed blood vessels continue to proliferate. During the repair phase, the acute pain is gone and goes to the sub-acute pain phase. The sub-acute pain can occur because of the scarring and immobilization of your limb. Immobilization makes your connective tissue stiff, has an impact on the loss of muscle mass, and weakens muscle strength.

The pain during this phase is natural, especially when you try to move your limb. At first, you can feel that you cannot even stand on your leg, raise your hand, or squeeze your fist; it depends on the location of the fracture. However, when rehabilitation starts and you gradually start to move your injured limb, the pain reduces because stretching, amplitude, and strength exercises will help you to recover and gain mobility and strength of the muscles as they were before the injury.

Remodeling phase

This is the late stage of bone healing that can last from a month to a few months. During this stage, the bone gets its original structure, shape, and mechanical properties.

Fully healed bone, restoration of limb amplitude, and increased muscle mass do not provoke pain anymore.

Is it possible to have chronic pain after the fractured bone healed?

It is possible that after the bone is healed, you can feel pain. This pain is called chronic pain, which can last six months or more. There are many causes of chronic pain:

• Neuropathic pain. This pain is very common after a lower limb fracture, and it is related to a poorer recovery process. Neuropathic pain can last for six months.
• Osteoporosis and arthritis.
• Contracture of the tendons, muscles, and other structures. Such movements can cause pain after immobilization of the limb.

How to manage pain during the healing process?

When you have a fracture, especially when it is complicated, it is important to immobilize the limb with a splint and try not to move to help heal quicker and reduce pain.

Moreover, it is important to elevate the broken bone and give it rest to improve the healing process. If the pain is very persistent the doctor will prescribe medicine to relieve pain.

Furthermore, the immobilized limb is getting weaker, which shortens the tendons and other tissues. To escape these events, contact your physiotherapist, and they will give you advice according to your situation on when it is safe to start moving the limb to get better results when the splint is removed and the limb needs to start rehabilitation.