Bilateral First Rib Fractures Likely Due To Hypophosphatasia

HISTORY: 18-year-old female college field hockey player presents with atraumatic bilateral first rib fractures that occurred approximately 6 weeks apart. She initially had acute right shoulder pain that started with a pop while doing a push-up. She was evaluated in the emergency room and diagnosed with right first rib fracture based on imaging. Approximately 6 weeks after the initial fracture, she had the other first rib fracture on the left side while working on her shoulder with a resistance band during a physical therapy session. Other than shoulder pain, she did not have other acute complaints. PHYSICAL EXAM: no skin changes, tenderness to palpation along the diffuse anterior aspect of shoulder and area superior to clavicle, no bony tenderness to clavicle, acromioclavicular joint, or scapula. Full range of motion with abduction, flexion, and internal and external rotation of the shoulder, but with pain at end of range. No winging of the scapula. Strength 5/5 in all planes, and neurovascularly intact. DIFFERENTIAL DIAGNOSIS: atraumatic bilateral first rib fractures due to osteopenia, relative energy deficiency in sport, hormonal dysregulation, osteogenesis imperfecta, or hypophosphatasia. TESTS AND RESULTS: XR ribs demonstrating bilateral first rib fractures; DEXA, NM bone scan, and CT chest with contrast all showed no abnormal findings. Labs: positive for low alkaline phosphatase - bone (2/3), hypercalciuria on 24-hour urine; unremarkable for TSH, FSH, PTH, Ca, Na, K, Mg, phos, Vitamin A/D, IGF-1, DHEA, CBC, SPEP, RF, ANA, C-telopeptide, celiac panel, dexamethasone suppression test; pending: vitamin B6, hypophosphatasia/hypophosphatemic rickets panel. WORKING DIAGNOSIS: atraumatic bilateral first rib fracture secondary to hypophosphatasia. MANAGEMENT AND OUTCOME: currently pending additional labs with plans to pursue genetic testing to confirm the working diagnosis of hypophosphatasia. Conservative management with implementation of activity modification, as well as calcium 600 mg and vitamin D 1000 IU daily.