Resident, PGY-3 Community South Osteopathic Family Medicine Residency Indianapolis, Indiana
Introduction: Anterior tibial shaft stress fractures are common in many athletes, however this case is unique because of the worsening imaging results after rest, and unusual treatment strategy for a case that shows the "dreaded black line". This case shows that even with a grim prognosis requiring surgery can be dealt conservatively with the right tools and patient compliance.
Case Study: 21 year-old female runner presented to the clinic for right mid-shin pain associated with running. There was no clear inciting event however had had worsening of this pain for the last month. One recent, particularly difficult, workout did flare her symptoms drastically. She has had normal menses without history of stress injuries nor fractures and did not report avoiding any food groups in her diet. Initial X-ray showed a small horizontal linear lucency in the mid-tibia concerning for a fracture. A subsequent MRI identified a grade II bone stress injury. At this time, the patient was advised to proceed conservatively without running or lower body weightlifting. She returned 3 weeks later with minimal improvement. She had not been able to wear the boot consistently due to pain associated with direct contact. A repeat X-ray at this time showed a more apparent mid-tibia lucency.
Patient elected trial of conservative management after discussion of risks and benefits of surgical and conservative options.
Subsequent visits showed improvements in X-ray imaging as well as in activities of daily living and tolerance of increasing difficulty of workouts such as swimming, pool runs, biking and elliptical exercises. She has been able to work through Alter-G treadmill returnto- running progression without worsening of her pain. This case demonstrates one example of a runner with tibial shaft stress fracture with imaging evidence of the "dreaded black line" returning to running without operative management via intramedullary tibial nailing.
Discussion: Anterior tibial shaft stress fractures are commonly treated with intramedullary tibial nailing, sometimes even as first-line management. Due to this poor prognosis, the X-ray finding has earned the name, the “dreaded black line”, which describes a locally thickened cortex with a V-shaped radiolucent defect of the anterior tibial cortex. It is thought that these occur due to the lag in osteoblastic activity after osteoclastic activity related to bone loading and strain during exercise. Given this pathophysiology activity modification and therapy programs involving graduated running progression may be a sounder principle of management in less severe cases.
