Working Diagnosis:
Femoral shaft stress fracture versus early osseous neoplasm with Ewing's Sarcoma felt to be most likely.

Treatment:
Following the femoral radiographs in Sports Medicine Clinic he was placed on crutches and instructed to remain non-weight bearing for a suspected femoral shaft stress fracture. Following the MRI we discussed with patient and mother that stress fracture was still the most likely etiology, but we referred him for orthopedic oncologic evaluation.

Outcome:
After his initial consultation with orthopedic oncology, concern for possible early Ewing's Sarcoma remained, but with no other concordant symptoms and with his running history, femoral shaft stress fracture was still thought to be more likely. After 4 weeks, follow-up radiographs were obtained. This showed a more typical cortical healing pattern that would be consistent with stress fracture. Case Photo #5 Case Photo #6
The patient was allowed to begin weight bearing. He was scheduled for repeat Xray in 3 weeks. Following clearance by orthopedic oncologist, that physician planned to have patient follow-up in sports medicine for recommendations on how to safely return to running, and recommendations for rehabilitation.

Author's Comments:
The patient's subsequent follow-up Xrays showed continued healing consistent with stress fracture. He continues to be followed by orthopedic oncology and is awaiting clearance. Case Photo #7 Case Photo #8

Editor's Comments:
Stress fractures are a commonly encountered problem in sports medicine, constituting about 10% of all sports related injuries [4]. They account for a significant percentage of overuse injuries and up to 15% of injuries in runners. The majority of stress fractures occur in the lower extremity with stress fractures of the tibia, metatarsals, and fibula being the most commonly reported in the literature. Only 2.8-7% of reported stress fractures affect the femur, with the majority in athletes occurring in the proximal third [2]. Analysis has shown that the junction of the proximal and middle third of the femur is particularly susceptible to repetitive submaximal stress, thought to be contributed to the tubular shape and bowed configuration of this long bone [1].

Athletes typically present with vague complaints, thus emphasizing the crucial role of a thorough history and specialize testing to assist in making the diagnosis. Information such as a sudden increase in mileage or intensity in training, incorrect footwear, or a change in running surface should raise suspicion to further investigate for a stress fracture [1]. On physical exam two tests are commonly employed including the fulcrum and one leg hop tests. This athlete was not tested but I suspect each would have been positive.

As in this case, standard radiographs are usually the first line of imaging, although at the time of symptom onset they are positive in only 30-70% of cases [3]. Diagnosis is confirmed by MRI or bone scan, with MRI the preferred choice due to higher specificity and similar sensitivity [1]. Treatment modalities for stress fractures include modified rest with gradual resumption of activities, assessment of biomechanics, footwear modification and orthotics, modified weight bearing, assessment and improvement of flexibility and strength, compression modalities, and even intramedullary nailing for some stress fractures [5].

Highlighted in this case is the importance of thoroughly investigating the joint above and below the focus of pain, as pain is often referred beyond the origin. As in this case, reimaging with radiographs to include the hip to include the femur further directed the clinician toward the underlying process. In addition, this case also emphasizes the utilization of MRI to differentiate stress fractures from other pathologic processes such as neoplasm.

References:
1. Stress fractures of the femoral shaft in athletes: a new treatment algorithm. Ivkovic A., Bojanic I., Pecina M. et al, Br J Sports Med 2006; 40: 518-520 

2. Femoral stress fractures. Boden. Clin Sports Med 1997; 16:307-17
3. Stress fractures in athletes. A study of 320 cases. Matheson GO, Clement DB, McKenzie DC. Am J Sports Med 1987;15:46-58.
4. Stress fracture: a review of 180 cases. Brukner P, Bradshaw C, Khan K. Clin J Sports Med 1996;6:85-9
5.Treatment of stress fractures in athletes with intravenous pamidronate. G.W., Brunet M.E., Manning M.R.. Clin J Sport Med (2005) 15 : pp 92-94.

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