Unlikely Leg Pain In A Cross Country Athlete

HISTORY: A 15 year old female cross country athlete presented for 2 months of right knee and thigh pain that progressively worsened causing her to be unable to run and has pain with walking. Upon chart review, it was noted that she had a history of an eating disorder (bulimia) 2 years prior. She was treated with calcium and vitamin d supplementation previously and is currently not on any supplementation. Denies any relapse of her eating disorder since then. Denies any palpable pain in the right thigh or knee but is unable to lay on her right side when sleeping. Denies any numbness or tingling in the right leg. PHYSICAL EXAMINATION: Right lower extremity examination revealed no effusion or overlying erythema. Tenderness noted at the medial patellar facet. Pain-free at the ASIS, AIIS, hip joint, or entire length of thigh. Hypertonicity noted within the hip flexors and hamstrings bilaterally. Range of motion of the right knee is 0-135 degrees and right hip of 5-110. Special testing showed pain with single leg stance and single leg hop in right thigh. DIFFERENTIAL DIAGNOSIS: 1. Patellofemoral syndrome2. Slipped capital femoral epiphysis3. Femoral stress fracture TEST AND RESULTS: Right femur and hip x-ray -No fracture, malalignment or focal osseous lesion. No localized soft tissue abnormalityRight femur MRI -In the region of the midshaft of the right femoral diaphysis is abnormal marrow signal intensity, associated with overlying small amount of edema about the medial aspect of the mid femoral diaphysis with small amount of early periosteal reaction and elevation along the medial cortex in this region FINAL WORKING DIAGNOSIS: Right midshaft femoral stress fracture TREATMENT AND OUTCOMES: 1. Immobilization of the right lower extremity with crutches and non-weight bearing for 2 weeks, then progressed to weight bearing as tolerated for 2 weeks 2. DEXA scan showed no osteopenia or osteoporosis 3. Laboratory studies showed normal calcium, vitamin D, phosphorus and magnesium levels 4. Physical therapy was started at onset of injury to work on stretching and strengthening on the lower extremities with progression to weightbearing exercises after 4 weeks 5. Able to slowly progress to return to run program with increased distance of walking after 2 months. Increased to jogging and light running after 3 months without pain