Working Diagnosis:
Healing osteochondritis dissecans with new grade 3 distal femoral stress reaction

Treatment:
Mother and patient were informed of the results of the MRI. The patient was held out of running until follow up. She was started in physical therapy for quadriceps, hip, core strengthening, and functional movement to prevent recurrence. She began to train in aqua running during that time.

Outcome:
The patient was seen for her final follow up eight weeks after discussing her MRI. She was progressing well through therapy and aqua running. In true runner fashion, she had run a mile each of the prior two days without formal release. She denied any pain during therapy, running, or physical examination. She was released to running through a return to run plan developed by her physical therapist.

Author's Comments:
Femoral stress reactions are not uncommon in athletes, accounting for up to 20% of sports medicine clinic injuries. It is unusual to have a stress reaction after an acute injury, especially where management required protected weightbearing and activity modification. Very few examples of stress reactions after OCD lesions exist in the literature, so mechanism is not well described. Altered biomechanics after injury could have led to an overload of bony stress. Healing OCD might have created a mismatch between native bone strength and the mechanical load placed on the bone. Additionally, the increased energy demands required for OCD healing might have predisposed the patient to stress reaction.

Editor's Comments:
Osteochondritis dissecans (OCD) and femoral stress reaction may indicate inherent bone pathology. Recommend considering further evaluation with labs and DEXA scan. Also genetic mutations have been linked to OCD.

Stattin EL, et al. Novel missense ACAN gene variants linked to familial osteochondritis dissecans cluster in the C-terminal globular domain of aggrecan. Sci Rep. 2022 Mar 25;12(1):5215.

References:
deWeber, K. (2022, June 23). Overview of stress fractures. UpToDate. htttps://www.uptodate.com/contents/overview-of-stress-fractures
Karadsheh, M. (2021, October 5). Osteochondritis Dissecans. Orthobullets. https://www.orthobullets.com/knee-and-sports/3028/osteochondritis-dissecans
Gaillard, F., Jadeja, R., Bell, D. (2008, May 2). Osteochondritis dissecans. Radiopedia. https://radiopedia.org/articles/osteochondritis-dissecans
Chmiel-Nowak, M., Knipe, H., Weerakkody, Y. (2020, February 20). MRI grading system for bone stress injuries. Radiopedia.
https://radiopedia.org/articles/mri-grading-system-for-bone-stress-injuries?lang=us
Patel, D., Roth, M., Kapil, N. (2011). Stress fractures: diagnosis, treatment, and prevention. American family physician, 83(1), 39-46. https://pubmed.ncbi.nlm.nih.gov/21999126/
Gorbachova, T., Melenvsky, Y., Cohen, M., Cerniglia, B. (2018). Osteochondral Lesions of the Knee: Differentiating the Most Common Entities at MRI. RadioGraphis, 38(5). 1478-1495. https://doi.org/10.1148/rg.2018180044
Sanchez, S., Arlata, T., Arshad, S., Cheng, S., Saunders, A. (2022, September 16). Knee Injuries. UTMB Health Pediatrics. https://www.utmb.edu/Pedi_Ed/CoreV2/musculoskeletal/Musculoskeletal15.html
Skalski, M. (2013, January 14). Fredericson MRI classification of medial tibial stress syndrome. Radiopedia. https://radiopedia.org/cases/fredericson-mri-classification-of-medial-tibial-stress-syndrome

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