A progressive overload bony injury is known by several names: stress reaction, stress response, or stress fracture. This type of injury results from chronic repetitive stress to a bony region, to which the bone cannot adapt at a fast enough rate. As this progresses over time, the irritation becomes worse. If this lasts long enough, a legitimate fracture line presents from where the irritated bone begins to lose its structural integrity.
These types of injuries are generally low risk and respond well to conservative management with exercise therapy. However, some regions of bone can be “high risk” due to their location and the structures that they support. For instance, a stress response in the neck of the femur, or a few of the bones of the medial ankle (talus, navicular, medial malleolus of the tibia for those who would like to dive deeper), tends to warrant more external interventions and many more precautions, including crutches, orthopedic referral, etc. These regions, and a few others, support a majority of the weight of our bodies as we go throughout the day. Even the slightest compromise to these areas should be taken seriously to avoid substantially more serious problems in the future. Fortunately, a majority of “high risk” stress responses are uncommon, even in those who run large volumes weekly.
High risk stress responses should be treated well into the conservative side until cleared to do more activity by an overseeing specialist physician. Should we suspect or confirm a high risk stress response in our office, we always refer out to a specialist to help oversee treatment. We take zero risks with these cases and believe more eyes on the injury will help provide the best prognosis for the patient. Going forward, we will be talking of treatment for low risk stress responses only.
More commonly, if the average individual develops a stress response, it will be a low risk, or non-weight bearing one. The most notable would be severe “shin splints”. The injury mechanism of “shin splints” pulls at the attachment site of the posterior tibialis muscle as it attaches to the back of the shin (tibia bone). This irritates the attachment tissue as it anchors the muscles into the bone. Should this mechanism of irritation continue without being addressed, the bone can become irritated as well.
When the bone is chronically overloaded and not allowed to adapt, the bone reacts to varying degrees. This spectrum of injury usually begins with a small swelling in the central portion of the bone, known as the marrow. Even swelling in the sliver of sheath around the bone, the periosteum, is noted with some early bony stress responses. As the chronic overload continues, the irritation progresses to more of the marrow, then to the cortex, or hard part of the bone itself. Finally, as the overload advances, an actual crack begins to develop in the bone. As mentioned earlier, this is our fracture line. Should the irritation surrounding the stress response not be addressed, the injury will continue to worsen.
So, how are these types of injuries treated? Like any tissue, bone adapts to the forces that are placed upon it. Bony stress responses are progressive overload injuries. They result from the bone not being able to adapt to the forces that are being placed upon it. The good news here is that there are low level activities that can be done to help the injured bone remodel in low risk stress responses. As long as there is no pain, simple activities such as standing or walking can be used to treat the injury. This is due to the weight of the body providing force through that bone that it must adapt to. As the treatment continues, we like to refer to a combination of time, symptoms, and function to determine the next stages of rehabilitation. Bone takes time to heal fully, so we have to give it that due time. However, as long as we are close to those time markers, moving well, and with little to no pain, we can progress close to as rapidly as many other injuries. Adding exercises that target the injured area, not only the bone but the surrounding supporting muscles and tissues, to adapt and remodel will stimulate recovery and healing of those tissues. Progress these exercises, and continue along with the previous guidelines (move well, little to no pain, timeline of bone healing, etc) and the injured bone will continue to heal until you are fully recovered.
Disclaimer: It is important to note that this is not intended to be a guideline for treating bony stress responses. Our hope is to provide knowledge so that individuals may be able to better understand injury types. Should you feel like you have any of these, it is important to immediately stop impact loading of the tissue and other movements that irritate the injured area, and call your doctor to receive a consultation. Should you need more assistance, please feel free to give us a call and we will do our best to help.