When going over the types of fractures during one of our lectures I wondered how some of them could possibly be treated. At the time the only treatment I knew of were casts and internal fixations, but these didn’t seem to be sufficient for things like comminuted fractures. After doing some research I came across external fixations, which can aid in treating more complicated fractures alone or in combination with internal fixations. What confused me at first was why external fixations had any advantage over internal fixations, which is what motivated me to research this. In this essay I will go over how external fixations aid in bone repair and what use cases they have.
An external fixation is a device that provides support via a structure made of bars, clamps, and rings (situationally) which are fixed to the broken bone(s) with screwed in rods that emerge from the flesh. My first bit of skepticism was in regards to infection, which seemed like an obvious downfall with protrusions. I was surprised to find that though it was an issue, it was less prominent than infection in internal fixations. I believe this is due to the procedure being far less invasive. Additionally, as a less invasive procedure it has a use case for people with slowed tissue repair (Diabetes, peripheral vascular disease, etc). As well as this, there is less damage to the bones blood supply in an external fixation (2). In one study comparing a intrameduilary rod (IMR)(an internal fixture) and external fixture (EF) on a broken cortical bone, it was found that, “At 14 days, the blood flow to the endosteal cortex was still significantly lower with IMR than with EF.” Another great advantage over other methods like casting or slinging is the finer precision and greater ease of adjustment absent even in internal fixations. And even in situations where a either type of fixation are comparable, the external can win out in situations where there is too much swelling to safely perform surgery. Though there are many benefits to an external fixation, there are also downsides. Though they don’t immobilize like some methods, they are still large and cumbersome to move around with. As well as this, even though they’re less likely to develop infection than the internal variety, they are a lot higher maintenance. A part of that maintenance includes frequently checking for fractures caused by the rods and loose rods which can lead to infection. If indicators of infection are present there may be need for topical and oral antibiotic use, pin removal, preventative removal at loose sites, and in more serious cases, removal of the entire structure with debridement, irrigation, and heavy antibiotic use (3).
In addition to what I’ve learned from my sources, I also have a theory based on what I’ve learned in class as to how an internal fixation may interfere with core stages of bone repair. This may pose another advantage for external fixation. According to my textbook, within 6-8 hours of a breakage a hematoma forms, and around the 48 hour mark the internal and external calluses form along with new blood vessels. At both of these stages there is a bulge in the bone. The insertion of a flat plate onto this protrusion may cause deformation as even at the second stage as the callus is flexible being made of hyaline cartilage. In the third stage spongy bone fills in this bulbous callus and in the fourth the excess is remodeled down near its original size with the re-addition of compact bone. If the plate reduces the size of the external callus and in turn the spongey bone size, there may be consequences in the remodeling process due to there being less material to reduce from (Open stax p. 240). And even if this is not an issue of development, it would surely contribute to inflammation, which is a well know downside to internal fixations.
Overall, external fixations are a highly effective method of stabilization despite the downsides. As early as 2000 years ago Hippocrates was recorded as using external fixation, and since many advancements have made it significantly safer and more versatile. With advancements in material science for both strength and anti-microbial applications, I think this treatment has a lot of potential on top of its already robust use cases.
(1) Smith, S. R., Bronk, J. T., & Kelly, P. J. (1990). Effect of fracture fixation on cortical bone blood flow. Journal of orthopaedic research : official publication of the Orthopaedic Research Society, 8(4), 471–478. https://doi.org/10.1002/jor.1100080402
(2) Summit Health. (n.d.). External fixators. Summit Health. Retrieved November 24, 2022, from https://www.summithealth.com/external-fixators
(3) Bible, J. E., & Mir, H. R. (2015). External fixation Principles and Applications. Journal of the American Academy of Orthopaedic Surgeons, 23(11), 683–690. https://doi.org/10.5435/jaaos-d-14-00281