Working Diagnosis:
Stress fracture of the right distal third metatarsal.

Treatment:
The patient was immobilized for three weeks, using a standard walking boot. Repeat x-ray imaging of her foot demonstrated interval healing Case Photo #6 , Case Photo #7 . She was offered a referral for physical therapy, however declined. A gradual return to activity, including no high impact lower extremity activity prior to 6 weeks, was recommended. A nutrition referral was placed due to patient’s prior history.

Outcome:
Patient had multiple factors concerning for relative energy deficiency syndrome including, prior history of stress fracture, low bone, mass and had made comments during the initial evaluation body image dysfunction. Unfortunately, the patient did not schedule her sports nutrition evaluation.

Author's Comments:
Stress fractures are due to repetitive and excessive stress on bones resulting in accelerated normal bone remodeling and the production of micro fractures that may result in stress fractures with insufficient time for bone healing. Risk factors include poor nutrition, inadequate vitamin d levels, excessive activity with limited rest or low level of physical fitness, female sex, poor bone health, smoking, and the female athlete triad (low energy availability, menstrual dysfunction, low bone mineral density). Maintaining a high index of suspicion is important for diagnosis as initial radiographs may be negative. MRI is the best test for diagnosis as it is both sensitive and specific. Treatment entails biomechanical stress relief, pain control, & gradual return to activity.

Editor's Comments:
The prevalence of bone stress injuries is higher in the running population. One study reporting running related bone stress injuries accounting for 69% of stress fractures (3,4). The foot and ankle are two of the most common areas bone stress injuries occur in athletes (3). As demonstrated by this case a high index of suspicion must remain as radiographs may not demonstrate any objective findings early in the course of symptoms. Advanced imaging, such as MRI, may be necessary to definitively diagnose a bone stress injury in the context of normal radiographs with high clinical suspicion. Bone stress injuries, historically have been classified as high risk (Superolateral femoral neck stress fracture, proximal 2nd or 5th metatarsal, navicular, talar neck, anterior tibial diaphysis) intermediate risk (medial malleolus, inferomedial femoral neck) or low risk (lateral malleolus, calcaneus, 1st, 3rd, 4th metatarsals) based on the biomechanical environment and natural history of the stress fracture (5). This simple classification is often used to help guide treatment, with high risk stress fractures typically requiring more aggressive treatment. It is important to recognize, while classification of the bone stress injury can be simplified into one of three categories; comprehensive treatment of a bone stress injury often requires more than just treatment of the osseous injury. Multiple intrinsic and extrinsic factors can play a role in the development of bone stress injuries. Intrinsic factors, which may not be easily modifiable, include age, sex, malalignment, hormonal imbalance*, vascular supply. Extrinsic factors, while theoretically more easily modifiable can present their own challenges. Of a variety of extrinsic risk factors, low energy availability (LEA) has been described as a common denominator among athletes presenting with bone stress injuries (4,6). In the last decade, The International Olympic Committee (IOC) described a syndrome affecting the physiologic function of multiple organ systems, naming this syndrome Relative Energy Deficiency syndrome (RED-s). It is a syndrome characterized by impaired physiologic function of multiple systems including skeletal, psychological, metabolic, hematological, cardiovascular, gastrointestinal, endocrine, immunological, and reproductive. Management of RED-S is complex and requires a multidisciplinary team to assure comprehensive care and safe return to sport. This case highlights some of the complexity involved with treatment of a seemingly simple bone stress injury. As mentioned early on, it is important to maintain a high index of suspicion for possible bone stress injury in the running athlete presenting with foot or ankle pain. However, it is just as important that one maintains an high index of suspicion for LEA and the potential additional consequences that may manifest as in the form of RED-S in that same athlete in order to provide proper care.

References:
1.https://www.aafp.org/afp/2011/0101/p39.html
2.https://www.uptodate.com/contents/overview-of-stress-fractures?search=stress%20fracture&source=search_result&selectedTitle=1~140&usage_type=default&display_rank=1
3. Greaser M. Foot and Ankle Stress Fractures in Athletes. The Orthopedic clinics of North America.47(4):809-822.
4. Johnston TE, Jakavick AE, Mancuso CA, et al. Risk Factors for Stress Fractures in Female Runners: Results of a Survey. Int J Sports Phys Ther. 2021;16(1):72-86.
5. Kaeding CC, Yu JR, Wright R, Amendola A, Spindler KP. Management and return to play of stress fractures. Clin J Sport Med. 2005;15(6):442-447.
6. Rogers MA, Appaneal RN, Hughes D, et al. Prevalence of impaired physiological function consistent with Relative Energy Deficiency in Sport (RED-S): an Australian elite and pre-elite cohort. Br J Sports Med. 2021;55(1):38-45.

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