Working Diagnosis:
The working diagnosis was bilateral tibial stress fractures due to iron deficiency.

Treatment:
The patient was treated with dedicated rest, avoidance of high-impact activities, physical therapy, and iron supplementation (initiated at 325 mg oral ferrous sulfate daily) with Vitamin C (for improved absorption) for three months. Repeat iron studies after three months of treatment revealed improvement in his serum ferritin. At his three month follow up, repeat physical examination revealed the patient was pain free and repeat radiographs displayed appropriate fracture healing.

Outcome:
As with other types of stress fractures, our patient progressed through a period of dedicated rest, activity modification, and fracture healing prior to return to sport. Given his iron deficiency, he was continued on iron supplementation to prevent further injury. Question remains about the underlying etiology of his iron deficiency without anemia, as our evaluation did not reveal one. While it appeared to be idiopathic in nature, further evaluation for occult malabsorption syndromes or consultation with hematology could be considered. Our patient elected to follow up with their original primary care provider for further monitoring and consideration.

Author's Comments:
Tibial stress fractures in a baseball pitcher with low-risk activity are rare. In a recent literature review, no such cases were identified. With atypical stress fractures, identifying the etiology is imperative. Risk factors include rapid progression of physical activity, diet poor in calcium, prior history of stress fracture, low bone mineral density, and iron deficiency. Iron plays an essential role in collagen synthesis, vitamin D metabolism, and overall bone mineral density. It is a frequently unrecognized source of poor bone health and low serum ferritin is suitable for making the diagnosis. The prevalence of iron deficiency in stress fractures is unknown. Treatment consists of iron supplementation and standard medical therapy. The optimal amount of iron supplementation is debated in the literature and further research is needed to establish such. Initiating treatment with standard oral therapy, often 325 mg of ferrous sulfate daily, is often sufficient. It is recommended to add vitamin C supplementation to aid with iron absorption. Repeat iron studies after 6 weeks of supplementation is recommended to monitor response to therapy. At this time, clinical evaluation for healing of the stress fracture should also be performed.

Editor's Comments:
Stress fractures should be included in your differential in patients presenting with bony tenderness not responding to conservative therapy. If stress fracture is diagnosed and no high risk activity is noted by your patient's history, initial workup should include, but not be limited to, comprehensive metabolic panel, complete blood counts, iron studies, vitamin D level, and parathyroid and thyroid hormone tests. Initial treatment of tibial stress fractures includes rest and stabilization as needed. This treatment can include a period of non-weight bearing and stabilization in a long air splint, knee splint, or hinged brace. This short period of non-weight bearing should end when the patient no longer experiences significant pain with ambulation. This should be followed by a regimented, progressive, phased rehabilitation program for the athlete. For stress fractures, supplementation with vitamin D and calcium can also help promote bone healing. Generally 12 weeks is adequate for the athlete to return to full activity, with continued pain being the limiting factor to return.

References:
1. Yanovich R, Merkel D, Israeli E, Evans RK, Erlich T, Moran DS. Anemia, iron deficiency, and stress fractures in female combatants during 16 months. J Strength Cond Res. 2011 Dec; 25(12):3412-21.doi:10.1519/JSC.0b013e318215f779.PMID:22080308.
2. Jung, Dong-Wook MD; Park, Joo-Hyun; Kim, Do-Hoon MD, PhD; Choi, Moonyoung MD; Kim, Shinhye MD; Kim, Hyonchong MD; Seul, Da-eun MD; Park, Soo Gyeong MD; Jung, Jin-Hyung BS; Hand, Kyungdo PhD; Park, Young-Gyu PhD. Association between serum ferritin and hemoglobin levels and bone health in Korean adolescents, Medicine: December 2017-Volume 96-Issue 51-p e9403 doi: 10.1097/MD/.0000000000009403.
3. Yanovich, Ran; Merkel, Drorit; Israeli, Eran; Evans, Rachel K; Erlich, Tomer; Moran, Daniel S Anemia, Iron Deficiency, and Stress Fractures in Female Combatants During 16 Months, Journal of Strength and Conditioning Research: December 2011 - Volume 25 - Issue 12 - p 3412-3421 doi: 10.1519/JSC.0b013e318215f779

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