There are 206 bones in the human adult body. These bones are just as important to the everyday function as organs and other soft tissues. The hard outer layers of bone store minerals, red marrow produces red blood cells, and yellow marrow stores fat. But what happens when a bone breaks, or fractures? How do bones repair themselves?
If you suffer from certain medical conditions like cancer or osteoporosis, you're more likely to experience a fracture or broken bone. Accidents, usually heavy falls, are the most common causes of broken bones. Knowing how bones repair themselves can give you peace of mind if you're already injured.
How do bones repair themselves? After some research, we discovered the intricate and complex way bones take care of themselves when injured.
How Do Bones Repair Themselves?
Our bones are constantly repairing old bone tissue every day; however, when a bone breaks, that process is sent into overdrive with some help from special cells from the immune system. The body works hard to clean away any bacteria and bone particles.
Before we dive into how bones heal themselves, we should cover types of bone fractures. Some may only need a simple cast to aid the healing process, while others will also require surgery to secure the broken bones in place with metal pins.
Types Of Bone Fractures
Stress fractures are the lesser evil of bone fractures. They usually occur in the legs and feet of athletes and physically active adults. This fracture is also the easiest to prevent. Doing proper warm-up stretches, cool downs, and strength training exercises are a few simple ways to avoid stress fractures.
A greenstick fracture (occurs in children only due to their bone structure) refers to a bone that bends and cracks, but doesn't break all the way through.
A stable fracture is when the broken bones still line up, or are barely out of place. This is a simple type of break and typically only requires a cast.
An avulsion fracture refers to a break made by a muscle or ligament pulling on the bone. The word avulsion is derived from Latin, meaning “to tear off.” This type of fracture may or may not be serious and typically doesn't involve too much medical intervention.
An impacted fracture happens when one end of the fractured bone is driven into the other. Typically, it's caused by falling.
A pathological fracture happens when bones are weakened by disease and break with little force.
An open, or compound fracture happens when the skin breaks as the bone does. The bone may or may not be visible. This type of fracture is more likely to develop an infection.
A transverse fracture refers to the break being a horizontal line, straight across the bone, whereas an oblique fracture is angled and doesn't cut straight across.
The most complex type of bone fracture is referred to as a comminuted fracture, when the bone breaks into three or more pieces. These are the types of fractures that require surgery to ensure the bone heals properly, in the right place.
Finally, compression fracture, which is also known as a crush fracture, usually only occurrs in the spine; often due to weakened bone structure.
How Do Bones Repair Themselves: The Bone Healing Process
Bones take about 6 months to several years to fully heal themselves. Most patients can bear weight on it after 12 to 16 weeks. During that time, the immune system kicks in. It sends out phagocytes to clear away bacteria and bone fragments from the fracture site.
A Timeline Of How Do Bones Repair Themselves
Throughout the process, a patient should take care not to stress the fracture site. While you may be able to use the injured bone, adult bones take a long time to fully remodel, sometimes as long as 3 to 9 years. In the meantime, material like cartilage and collagen work to keep everything in the right place.
At The Time Of Injury
One should take immediate action and see a medical professional. The length of time required for recovery depends on the location of the fracture along with the patient's age and health. Some fractures need to be lined up together to ensure a proper recovery.
The First Hours And Over The First Few Days
Right after the injury, freshly broken blood vessels work to form a clot around the fracture to protect the exposed bone and hold it in position. This will often be exhibited as swelling and inflammation around the break site. The blood clotting process is better known as a fracture hematoma. Then, tiny blood vessels grow into the hematoma to help all the special cells get to the fracture and continue the healing process.
Those special cells, called phagocytes, go to work. Derived from Greek, phagocyte means “cells that eat”: appropriately named, as they envelope and destroy unwanted materials found near an injury.
From Four Days To Three Weeks
Once the injury site is cleared of bacteria and dead bone and blood vessels, a tougher tissue replaces the blood clot. This provides more stability to the fractured area. This is actually a soft callus material made up of mostly collagen, so the bone cannot bear any weight or pressure yet.
This is still an important part of the process. Collagen is one the most important proteins found in the body, it is made of essential amino acids that help grow everything from our nails and hair to skin and bone. The body can't take collagen as it is. Fibroblast is responsible for processing the collagen for the body to use. Chondroblastsare responsible for developing a special type of soft cartilage, known as fibrocartilage. Working together, as a material known as fibrocartilage callus, the fibers of collagen and fibrocartilage bridge the gap of bone, which lasts about three weeks.
From Four To Twelve Weeks After Injury
At this point, the bone has set itself into position, but the bone cannot tolerate any pressure. It is still working hard to replace old bone tissue and the soft callus material.
After that, a hard material forms, known as bone callus, replacing the soft callus. This allows osteoblast to build up the proper minerals to form the hard outer layer of bone, giving necessary protection and stability.
From Twelves Weeks To The Full Remodel
More special cells, called osteoclasts and osteoblasts, are the main foot soldiers involved to build up those minerals and break down the extra bulk of bone material around the fracture site to return the bone to its original shape. This is the longest phase, but patients can safely use the bone without worry at this point. Complete bone remodeling is a very slow process. It may take even longer for patients who smoke, used to smoke, or suffer from medical conditions like osteoporosis, diabetes, or cancer.
While the bone remodels itself, the callus decreases, the bone becomes compact (but is still forming), and blood circulation improves, sending in much needed nutrients to keep building the bone. While it may seem counter-intuitive, bearing weight on the injury can help the healing process, but only once the bone has healed enough.
How Do Bones Repair Themselves: Recovering From A Bone Fracture
Whether or not you have broken a bone before, it can be a scary experience. It is always best practice to seek help from a medical professional. Depending on what bone it is and how severe the break is, other complications can arise.
Patients should do their best to follow their doctor's specific advice and report any sudden changes or increase in pain. Occasionally, a bone fracture might not heal correctly. In these cases, symptoms like swelling, tenderness, and aching pain can be felt in the break site.
It is not often that a broken bone requires surgery, but if it does, there is no substitute.
Sometimes doctors perform surgery to remove fragments of bone or foreign material. Surgery may also be necessary for aligning the pieces of bone with metal rods, screws, or pins to keep it held in place so it can heal correctly. Serious breaks to the hip or other joint often require an artificial replacement.
Smokers, diabetics, and the elderly often are victims of complications due to restriction of the blood vessels and other health factors. Keep in mind, complications from a bone fracture are rare.
In compartment syndrome, muscles near the fracture site swell so tightly that oxygen can't enter the high-pressure tissue. Without enough oxygen, the muscle tissue can continue to swell until the muscle tissue dies, possibly making the injury worse.
Pulmonary embolism occurs when the blood clot breaks loose from the fracture site and blocks a lung artery. This condition can be common with hip and pelvis fractures, accounting for an estimated one-third of hip-fracture deaths.
Individuals who smoke or have diabetes should take extra caution while a broken bone is healing. Smokers should try to quit, at least while recovering, and diabetes patients should keep a close eye on their glucose levels, since high blood sugar can obstruct the healing process,
Individuals At Risk
According to the American Academy of Orthopaedic Surgeons, younger individuals are more likely to break their radius bone of their wrist than other bones. Surgeons see the highest number of hip fractures in individuals over 75 and, in general, the most common bone breaks occur in men under 45 and menopausal women over 45.