summary A rib stress fracture in an uncommon site of stress fracture that typically occurs due to repetitive contraction of the chest wall muscles. Diagnosis can be made with radiographs but often require CT or MRI for accurate diagnosis. Treatment consists of rest, analgesia and cessation of inciting activity for ~4-6 weeks. Epidemiology Incidence uncommon site of stress fracture Anatomic location first rib common site occurs anterolaterally activities associated with stress fx include baseball pitching, basketball, weightlifting and ballet middle ribs (4-9th) occurs laterally and anterolaterally increased incidence in competitive rowers posteromedial ribs more commonly occurs in novice golfers Risk factors amenorrhea osteopenia / osteoporosis extreme overuse / repetitive use repetitive coughing paroxysms Etiology Pathophysiology pathoanatomy repetitive contraction stress placed on a rib during repetitive contraction of an attached muscle accentuated during training because muscles strengthen more rapidly than bone muscle fatigue during prolonged activity places a bone at risk for fracture by lessening the ability of a muscle to absorb and dissipate opposing forces anatomic sites of weakness first rib stress fx groove for subclavian artery is site of weakness due to superiorly directed forces from the scalene muscles and inferiorly directed forces from the serratus anterior and intercostal muscles Presentation History in cases of acute injury may hear "snap" (complete fracture of fatigued bone) while performing activity (i.e., throwing, batting, lifting) Symptoms pain insidious onset worse with coughing, deep inspiration and overhead activities Physical exam palpation focal tenderness directly over affected rib with advanced injuries, palpable callus may develop Imaging Radiographs recommended views AP chest findings x-rays are negative for fracture in as many as 60% of patients with rib fracture of any etiology Bone scan indications when x-rays are negative and clinical suspicion remains findings increased activity CT scan indications can be helpful when there is concern for pathologic fx can help localize an uptake abnormality in the costotransverse region, where the anatomy is complex findings clear delineation of fracture pattern MRI indications when x-rays are negative and clinical suspicion remains avoids the use of radiation used more commonly than bone scans in athletes findings marrow edema consistent with stress response; fracture line may or may not be seen Treatment Nonoperative rest, analgesia, cessation of inciting activity for ~4-6 weeks, correction of training errors or faulty mechanics indications majority of rib stress fx outcomes majority heal uneventfully Complications Non-union