When someone breaks a bone, no one needs to think about the next course of action. Almost immediately, the patient will likely be brought to the emergency room for specialized care. From there, they would expect the healthcare practitioner to fix what is broken and send them on their merry way.
But what happens if a broken bone doesn’t heal properly?
How do bones even heal?
In medical speak, a broken bone is known as a fracture. Most fractures undergo a predictable step-by-step healing process. It starts with the formation of a blood clot from the 1st to the 5th day after the injury. This clot would form the temporary frame for the latter stages, but it also calls to action certain cells that stimulate the healing process. After around a week, a callus starts to form. It starts as a flexible cartilaginous callus and eventually becomes a hard, calcified, bony callus. New blood vessels wiggle into the callus until one is left with an immature bone.
The last stage of healing is called bone remodeling, where this immature bone is slowly replaced with something sturdier. It must be noted that bone remodeling is a process that lasts anywhere from several months or several years. The body needs to work to regenerate that normal bone structure.
Most fractures go through secondary bone healing, the steps of which were laid out above. However, some bones undergo primary bone healing, which skips out the formation of a callus. Though ideal for healing, this can only happen with very specific types of fractures where the broken pieces can be fitted as closely as possible to each other.
Of course, the reality is far from this. Up to 10% of fractures can end up with delayed or failed healing or a malunion of the bones.
Related Article: Comparison Of Ankle Sprain Versus Fracture
What are the signs a broken bone is not healing?
When a fracture is not healing properly, this is referred to as nonunion. Healthcare practitioners define a standard nonunion as a “fracture that persists for a minimum of nine months without signs of healing for three months.” However, not all bones heal at the same rate and certain necessary medications can slow down fracture healing. Doctors would have to check X-rays of the fractured limb to determine whether there is evidence of fracture healing--- often seen in the thickening of the fracture line.
So when should we start to get worried about fracture healing and book that doctor’s appointment?
Ideally, after a fracture gets treated in a hospital, the doctor would schedule regular follow-up appointments to monitor the healing process. These scheduled consults are to catch any infections, complications, or problems with healing before they become a big problem. The improvements between consults would be a better gauge of healing compared to the presence or absence of certain symptoms.
But a big sign that the broken bone is not healing is the persistent pain at the fracture site with weight-bearing. See, the broken bone would cause pain both because of the breaking or because of the surgery to fix it. However, it is expected for the pain to lessen and go away as time heals the wound. What aggravates the pain may differ depending on where the fracture is. A fracture in the leg may continue to hurt when a patient tries to stand, when they try to lift a bag if the fracture is in the arm.
While not specifically a sign that the bone is not healing, redness and pus draining from the surgical site may herald an infection. The infection in turn, may cause problems in bone healing. But what else would create problems for a healing fracture?
What causes nonunion in bones?
Nonunion of a broken bone is a complex issue and may have multiple causes working at the same time, each factor increasing the chances for healing problems dramatically.
A study done in 2018 found that older patients who had fractures on the legs, specifically tibial or femoral shaft fractures, were more likely to be admitted for fracture healing complications. Femoral fractures or fractures of the leg were also at greater risk for nonunion if the injury included a break in the skin, opening it up to the possibility of an infection. While resting an injury is generally good, a delay in weight-bearing or walking on the injured leg only after 12 weeks increases the risk for nonunion. Tobacco use, often associated with delayed wound healing in general, also increases the risk for nonunion in broken leg bones.
A 2014 systematic review reported that displacement was the biggest predictor of nonunion for fractures of the clavicle. Displacement means that the bone isn’t perfectly aligned to each other for one reason or another. This ends up with either a malunion where the bone heals irregularly or a nonunion where it doesn’t heal at all.
Lastly, a recent study determined that 1.3% of jaw fracture patients developed malunion or nonunion of the jaw bone. Like in the study of leg fractures, having the fracture pierce through the skin increases the risk of improper healing of the jaw bone. Another risk factor is the delay in treatment, specifically when surgical treatment was not done until six to seven days after the fracture. This hammers in the idea that a broken bone should be treated immediately.
But now that one has a bone that isn’t properly healing, what can be done?
Treatments for nonunion of fractures
As with most injuries, treatment depends on the affected bone as well as the type of fracture. For some, initial non-surgical treatment may be suggested where the fracture brace is kept on to give the bone a bit more time to heal.
Another option that doesn’t involve surgery is a pulsed low-intensity ultrasound where the bone is stimulated to encourage healing. With ultrasound, the rates for the bones to heal properly range from 70-93% when done within six months after the last surgical procedure. For some fractures, surgery may be indicated to improve the stability of the bone or to stimulate healing. 
Broken bones or fractures normally follow a step-by-step process of healing. However, in some cases, the bones do not heal properly or at all. Immediate consultation with a healthcare professional and prompt administration of treatment can help fix this issue.
- Sheen JR, Garla VV. Fracture Healing Overview. [Updated 2021 May 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK551678/
- Thomas JD, Kehoe JL. Bone Nonunion. [Updated 2021 Mar 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK554385/
- Ekegren CL, Edwards ER, de Steiger R, Gabbe BJ. Incidence, Costs and Predictors of Non-Union, Delayed Union and Mal-Union Following Long Bone Fracture. Int J Environ Res Public Health. 2018;15(12):2845. Published 2018 Dec 13. doi:10.3390/ijerph15122845
- Taitsman LA, Lynch JR, Agel J, Barei DP, Nork SE. Risk factors for femoral nonunion after femoral shaft fracture. J Trauma. 2009;67(6):1389-1392. doi:10.1097/TA.0b013e318182afd0
- Jørgensen A, Troelsen A, Ban I. Predictors associated with nonunion and symptomatic malunion following non-operative treatment of displaced midshaft clavicle fractures--a systematic review of the literature. Int Orthop. 2014;38(12):2543-2549. doi:10.1007/s00264-014-2450-7
- Lander DP, Lee JJ, Kallogjeri D, et al. The Impact of Treatment Delay on Malunion and Nonunion After Open Reduction of Mandible Fractures. Facial Plast Surg Aesthet Med. 2021;23(6):460-466. doi:10.1089/fpsam.2020.0607