Snapshot A 63-year-old man presents to the emergency room with left arm pain after falling off the second step of his ladder. He has significant pain over the middle of his left arm. On exam, he is tender to palpation along the middle of his left arm and a small deformity is appreciated. He has weakness in wrist extension and metacarpal phalangeal joint extension. Radiographs of his left arm demonstrate a spiral midshaft humeral fracture. He is placed in a coaptation splint and discharged with plans to follow-up in one week. Introduction Clinical definition fracture of the humeral shaft Epidemiology incidence account for approximately 3% of all fractures increasing incidence in the elderly demographics bimodal age distribution fragility fractures in the elderly high-energy traumatic fractures in younger patients risk factors osteoporosis Etiology low-energy injury in elderly patients high-energy injury in younger patients Pathoanatomy normal anatomy spiral groove (also known as the radial sulcus) is a shallow depression in the center of the lateral border of the humerus bone radial nerve and deep brachial artery course along the spiral groove of the humerus Associated conditions radial nerve palsy forearm fractures shoulder dislocation Prognosis favorable low-energy injuries unfavorable high-energy injuries Presentation Symptoms arm pain weakness Physical exam deformity may or may not be appreciated depending on the location and severity of the fracture neurovascular examination before and after reduction is critical to identify radial nerve palsy or deep brachial artery injury radial nerve palsy (5-10%) results in loss of wrist extension (wrist drop) metacarpal phalangeal joint extension thumb abduction and extension Imaging Radiography indication always indicated if a humeral shaft fracture is suspected findings fracture patterns can vary spiral, transverse, and comminuted fracture locations can vary proximal, midshaft, and distal Differential Distal humerus fracture distinguishing factor radiographs will demonstrate a fracture in the supracondylar, lateral condylar, or medial condylar zones of the distal humerus Proximal humerus fracture distinguishing factor radiographs will demonstrate a fracture in the surgical neck or anatomic neck of the proximal humerus Treatment Nonoperative coaptation splint followed by functional bracing indication most humeral shaft fractures can be treated conservatively Operative open reduction and internal fixation (ORIF) indication severe fractures (e.g., open fractures and vascular injury requiring repair) Complications Radial nerve palsy neuropraxia most resolve over 3 months of observation