Working Diagnosis:
Proximal Fibular Fracture with a Lateral Ankle Sprain

Treatment:
The patient was placed in a cast boot and instructed to be non-weight bearing using crutches. At 2 week follow up, she progressed to weight bearing as tolerated with a boot, but continued to experience mild ankle pain and moderate knee pain. At 4 week follow up, she had nearly full resolution of lateral ankle pain with continued mild proximal fibula pain over the fracture site. She progressed out of the boot and started physical therapy.

Outcome:
At 10 week follow up, she had completely discontinued use of boot, completed physical therapy, and was performing short aerobic exercise and low weight bearing lower extremity exercises without pain. She returned to full activities and has not been seen by our clinic since. She returned to ROTC in a stepwise progression with low weight bearing lower extremity exercises, light running, 2 mile run, and the obstacle course, progressing as each step became pain free. Her total recovery time from injury lasted 13+ weeks.

Author's Comments:
The patient suffered a longer than expected recovery course. For a proximal fibular fracture, we would expect full healing of the bone 6 weeks after the injury, however displacement with callus formation was still occurring at our 10 week follow up, nearly 13 weeks after the initial injury. The patient was a young and otherwise healthy female, however there are several factors that may have contributed to this delay. A unique injury of a proximal fibula fracture and lateral ankle sprain with an ankle inversion may not behave like the musculoskeletal injuries that we are accustomed to seeing. Nicotine abuse and the patient’s daily vaping despite cessation counseling could certainly prolong the patient’s course as tobacco use is known to delay bone healing. Additionally, there was delayed diagnosis of fibular fracture by 3 weeks due to a distracting injury. The patient was full weight bearing during that time, and may have inadvertently delayed her course. Lastly, non-compliance to her treatment regimen may have played a role. The patient stated that she was compliant with her boot and weight bearing status, however her affinity for skateboarding and role in ROTC show how active a person she was prior to her injury.

We can not always expect the anatomy of the human body to react as research and data tell us that it should. Fall injuries can be difficult for patients to clearly recall and may present with multiple or atypical injuries. A thorough physical exam remains an important diagnostic tool, especially in the sports medicine field. Distracting injuries should not allow us to miss diagnoses as this can cause delayed recovery times. It is possible that this diagnosis could have been found sooner by practicing the principle of evaluating the joints proximal and distal to an injury. It is important to obtain proper imaging, even if some images are repeats in order to fully assess a patient. In similar patient’s where compliance is a concern, casting would be reasonable alternative to using a boot.

Editor's Comments:
Ankle injuries can often be more than just a sprain and especially when patients present with continued pain it is important to investigate other possible causes. Palpation of the entire fibula with any ankle injury is recommended.
Ankle fracture classification can help to determine the extent of ligamentous injury and the stability of the joint.
The Weber classification focuses on the integrity of the syndesmosis. Weber A is below the syndesmosis and the syndesmosis is intact. Weber B is at the level of syndesmosis and some of the syndesmosis is intact. Weber C is above the syndesmosis, the syndesmosis is ruptured and the joint is usually unstable.
The Lauge-Hansen system includes the mechanism of the fracture which helps to determine ligament involvement and ankle stability. These include supination adduction, supination external rotation, pronation abduction, pronation external rotation.

References:
Taylor, Benjamin. Ankle Fractures on OrthoBullets https://www.orthobullets.com/trauma/1047/ankle-fractures (accessed 11/15/2020)

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