Bones are amazing. They are blessed with a remarkable structure formed from calcium phosphate crystals that are carbon fiber strong and packed with many cell types and blood vessels. Bones are vibrant structures. Unfortunately, in the pantheon of human organs bone doesn’t get the respect it deserves. When pondering how our bodies function bone is usually an afterthought, an under-appreciated element of our human form. Most don’t think of bone as an organ at all, like they do the brain or heart. This is unfair. After all, can the heart or brain regenerate if broken? Bones are dynamic, their size and density change. They are plastic, changing shape in response to external forces and when healing.
Anatomy of Bone
Like the limbs of a tree bones provide strength and structure. Similarly, they require nourishment and they can break. Muscles attach to them. They protect vital organs and form our joints permitting movement. They are rigid and sometimes brittle. When they break the damage can vary along a broad spectrum. A fracture can be so small it resembles a hairline or so severe it shatters into uncountable tiny fragments. Bones can bend without breaking like saplings bowed by a fierce wind. They can be splintered, snapped, twisted, or crushed. Broken bones are usually contained within our skin but, every now and then, sharp edges poke through creating an open fracture.
The field of orthopedics focuses on this incredible tissue and the purpose of my post is to give readers who are unfamiliar with this subject an easily digestible overview of what bone is actually like and how broken bones are fixed.
In my novel, FRACTURED, the heroine, stem-cell biologist, Claire Hodgson has discovered laboratory methods to make this amazing tissue using three-dimensional biologic printers. Together with her research partner, Mark Thurman, they are pioneering new methods for treating complex fractures. I’m convinced this will be happening in the next decade as researchers and surgeons move biological tissue printing from the laboratory bench top to the hospital bedside.
Orthopedic surgery is a discipline that’s divided into many subspecialty areas. These include: pediatrics, hand, spine, sports medicine, shoulder and elbow, foot and ankle, adult reconstruction, oncology, and trauma. Orthopedic surgeons frequently treat patients in several of these areas. For example, my practice focuses on adult reconstruction (total joint replacement), sports medicine, and trauma. It’s the job of the orthopedic trauma surgeon to fix bones when they fracture.
In FRACTURED, Mark Thurman is an orthopedic trauma surgeon. He has spent a significant portion of his adult life learning to fix broken bones either with, or without surgery. Most readers have a good understanding of the nonsurgical treatment of fractures and have seen patients with casts or had to wear one as the result of an injury. Things are different when surgery is required.
When a bone absorbs enough applied energy it breaks. If the magnitude of absorbed energy is high enough an unstable fracture will result. This means the bone fragments cannot be held in proper alignment in a cast or splint. They will move and either not heal or heal at an undesirable angle resulting in a malunion. Or, if the fracture required immobilization for a long period of time to allow fracture healing the effected joint would be stiff when the cast was removed. In these instances surgery is needed.
X-ray of Fractured Tibia
Fractures can also be either open or closed. A closed fracture is one in which the skin remains intact, an open fracture results when the bones break the skin or if a laceration occurs over the fracture site exposing the bone fragments. Open fractures require surgical treatment. With closed fractures there is the option of surgical or non-surgical treatment.
When the right circumstances exist surgery is required. Orthopedic surgeons refer to this as fracture fixation. There are two broad categories of fracture fixation: external and internal, referring to the location of the stabilizing device. It will be located either outside the skin (external fixation) or underneath the skin (internal fixation). Thurman uses both methods to fix fractured bones in the book. In an opening scene at St. Matthew’s trauma center Thurman uses the technique of external fracture fixation to temporarily stabilize John Bristow’s shattered gunshot leg. Later on internal fixation is used in several surgical scenes. A third method of fixing fractures, a subset of internal fixation, is called intramedullary fixation where the stabilizing device is located inside the bone in the marrow canal. Thurman has had first hand experience with this technique and retains a metal rod in his right femur.
It is useful to think of these methods of fracture fixation in terms of the typical device used. External fixation involves the use of rigid steel and carbon fiber frames built outside of the fractured bone and attached with stainless steel screws, called half-pins (or pins). Internal fixation techniques use steel or titanium plates attached to bone with screws. This involves making a surgical incision and exposing a portion of the fracture, aligning the fragments and holding them in place with the plate and screws. Intramedullary fixation is when a titanium rod is inserted inside the shaft of a broken bone.
External Fixator Stabilizing a Tibia Fracture
These days in modern hospitals fractures requiring surgical treatment are fixed primarily with plates and screws or intramedullary rods. However, external fixation still has its place in the orthopedic surgeon’s toolbox. If a severe fracture occurs circumstances can dictate that the fracture be temporarily stabilized. This would be in the event the injury occurred in the middle of the night when optimum conditions for a technically demanding surgery are not available or if multiple surgeries will be necessary to clean the fracture of dirt and debris before final internal fixation is possible. In this instance the surgeon would apply an external fixator. The “ex-fix” frame holds the fracture rigidly stable in proper alignment allowing access to the injury site. This makes it easy, during future surgeries, to clean the tissues of contaminating material (dirt, grass, glass, pebbles, etc.). Orthopedists call this “damage control” when external fixators are used as a form of temporary stabilization.
Once the soft tissues have been cleaned (debridement) then the surgeon has the option to convert to internal fixation or intramedullary fixation after removing the external fixator frame.
Internal Fixation of a Tibia with Plate and Screws.
Internal fixation is generally preferred over external fixation for several reasons. First, is the obvious one, patients don’t like having a big bulky strange looking devise attached to their injured limb. If they bump into anything it hurts! The more important reasons are better, more rigid, fixation and less risk of infection. The small incisions where the half-pins enter the skin and drilled into the bone are frequently sites of bacterial ingress resulting in “pin track” infections. Internal fixation avoids these problems. Modern locking plate technology, where the screw heads thread into the plate provide a more rigid construct stabilizing the fracture fragments improving the chance for solid fracture union. This is particularly important in instances where joint surfaces are fractured. A fractured joint will become arthritic if not anatomically fixed.
Intramedullary Nail Fixation of a Tibia Fracture
When the shaft of a long bone breaks usually the best form of fixation is an intramedullary rod. This is when the stabilizing device is located within the fractured bone. The intramedullary canal of the bone is drilled, called reaming, to an internal diameter slightly bigger than the desired rod. The rod is then inserted down the canal, across the fracture site, all the way to the other end of the bone. Locking screws are placed through holes at both ends of the nail to prevent rotational motion. Once the patient recovers from the surgery and heals the fracture their pain is gone and the nail is left in place for the rest of the patient’s life.
There you have it, orthopedics 101. I hope this answers any questions readers may have about the basics of fracture treatment and stimulates more interest in this fascinating medical field.