Summary Humeral shaft fractures are common fractures of the diaphysis of the humerus, which may be associated with radial nerve injury. Diagnosis is made with orthogonal radiographs of the humerus. Treatment can be nonoperative or operative depending on location of fracture, fracture morphology, and association with other ipsilateral injuries. Epidemiology Incidence 3-5% of all fractures 20% of humeral fractures involve shaft 7 to 11.3 per 100,000 Demographics age 60% occur in patients older than 50 years bimodal age distribution login to view 3 more bullets elderly patients login to view 2 more bullets sex 70% occur in men when age less than 50 70% occur in women when age greater than 50 location 30% occur in the proximal third of the humeral shaft 60% occur in the middle third of the humeral shaft login to view 1 more bullet 10% occur in the distal third of the humeral shaft risk factors previous fracture history smoking in men elderly age osteoporosis Etiology Pathophysiology mechanism of injury ground level fall (60%) login to view 1 more bullet motor vehicle accident (~30%) login to view 1 more bullet pathologic fractures (4.3%) open fractures (3%) proximal third humeral shaft fractures common in older individuals often results from fall onto an outstretched hand resulting in impaction fracture at the surgical neck middle third humeral shaft fractures transverse fracture login to view 1 more bullet spiral fracture login to view 1 more bullet distal third humeral shaft fractures result from fall onto a flexed elbow Associated conditions orthopaedic floating elbow login to view 3 more bullets ipsilateral shoulder dislocation login to view 2 more bullets Anatomy Osteology humeral shaft extends from the surgical neck of the humerus to the supracondylar ridge and is cylindrical in shape distally humerus becomes triangular with the formation of the medial and lateral supracondylar ridges intramedullary canal terminates 2 to 3 cm proximal to the olecranon fossa radial groove is a depression along the posterolateral aspect of the humerus where the radial nerve and profunda brachii artery traverse Arthrology articulates with scapula proximally and distally with the radius and ulna Muscles insertion for pectoralis major deltoid login to view 1 more bullet coracobrachialis origin for brachialis triceps brachioradialis Nerves radial nerve exits axilla posterior to the brachial artery enters the posterior compartment of the arm through the triangular interval runs between the medial and long head of the triceps radial nerve is found medial to the long and lateral heads and 2cm proximal to the deep head of the triceps courses along the spiral groove then become anterior to the humerus login to view 1 more bullet radial nerve exits the posterior compartment through the lateral intramuscular septum 10 cm proximal to radiocapitellar joint login to view 2 more bullets ulnar nerve Enters the posterior compartment at the arcade of Struthers and runs medially towards cubital tunnel ~8cm from the medial epicondyle axillary nerve runs posterior to anterior around the proximal humerus 4 to 7cm from the tip of the acromion Compartments anterior compartment muscles login to view 1 more bullet vasculature login to view 1 more bullet nerves login to view 1 more bullet posterior compartment muscles login to view 1 more bullet nerves login to view 1 more bullet Classification Descriptive fracture location: proximal, middle or distal third fracture pattern: spiral, transverse, comminuted OTA bone number: 1 fracture location: 2 fracture pattern: simple:A, wedge:B, complex:C Garnavos classification location P: proximal M: middle D: distal j: extension into the joint morphology S: simple login to view 2 more bullets I: intermediate login to view 1 more bullet C: complex login to view 1 more bullet Holstein-Lewis fracture a spiral fracture of the distal one-third of the humeral shaft commonly associated with neuropraxia of the radial nerve (7-22% incidence) increases risk of radial nerve entrapment with the fracture Presentation Symptoms pain extremity weakness Physical exam swelling tenderness over the fracture site skin tenting examinination of overall limb alignment for deformity will often present with shortening and in varus preoperative or pre-reduction neurovascular exam is critical examine and document status of radial nerve pre and post-reduction login to view 2 more bullets Imaging Radiographs views AP and lateral login to view 1 more bullet transthoracic lateral login to view 2 more bullets traction views login to view 1 more bullet CT scan may be utilized if there is concern for intra-articular extension CT angiogram may be indicated if there is concern for vascular injury EMG indicated in the setting of nerve palsy to assess for nerve recovery, but is not indicated acutely as it will not dictate fracture management Treatment Nonoperative immobilization (coaptation splint or hanging arm cast for 7 to 10 days followed by a functional brace) indications login to view 12 more bullets contraindications login to view 8 more bullets outcomes login to view 9 more bullets Operative external fixation (Exfix) indications login to view 6 more bullets typically utilized as provisional fixation until definitive treatment can be performed, but may be used definitely if needed outcomes login to view 3 more bullets open reduction internal fixation (ORIF) indications login to view 26 more bullets techniques login to view 3 more bullets postoperative login to view 1 more bullet outcomes login to view 7 more bullets intramedullary nailing (IMN) indications login to view 6 more bullets outcomes login to view 7 more bullets total elbow arthroplasty indications login to view 2 more bullets Techniques Coaptation Splint & Functional Bracing coaptation splint or hanging arm cast applied until swelling resolves adequately applied splint will extend up to axilla and over shoulder common deformities include varus and extension login to view 1 more bullet functional bracing extends from 2.5 cm distal to axilla to 2.5 cm proximal to humeral condyles sling should not be used to allow for gravity-assisted fracture reduction shoulder extension used for more proximal fractures weekly radiographs for first 3 weeks to ensure maintenance of reduction login to view 1 more bullet External Fixation approaches proximal pins login to view 2 more bullets distal pins login to view 4 more bullets Open reduction internal fixation (ORIF) approaches anterior (brachialis split) approach to humerus login to view 3 more bullets anterolateral approach to humerus login to view 7 more bullets posterior approach to humerus login to view 49 more bullets techniques plate osteosynthesis commonly with narrow or broad, 3.5mm or 4.5mm dynamic compression plate or limited contact dynamic compression plate login to view 3 more bullets relationship of plate and radial nerve must be respected to prevent inadvertent nerve injury absolute stability with lag screw or compression plating in simple patterns apply plate in bridging mode in the presence of significant comminution may require the incorporation of condyles or dual plating in distal fractures bony defects up to 3cm can be dealt with via shortening, but larger defects (>3cm) may require grafting postoperative full crutch weight bearing shown to have no effect on union Intramedullary Nailing (IMN) techniques can be done antegrade or retrograde login to view 7 more bullets complication nonunion login to view 2 more bullets nerve injury login to view 8 more bullets shoulder pain login to view 6 more bullets postoperative full weight bearing allowed and had no effect on union Complications Nonunion no callous on radiograph and gross motion at the fracture site at 6 weeks from injury has a 90-100% PPV of going on to nonunion in closed humeral shaft fractures 82% sensitivity and 99% specificity radiographic union score for humeral fracture (RUSHU) 1 score per cortex on radiographs obtained 6-weeks from injury login to view 3 more bullets score ≥8 - 86% NPV for nonunion score <8 - 65% PPV risk factors humeral shaft fractures treated nonoperatively dependent on fracture pattern login to view 1 more bullet No significant difference in the rate of nonunion following open reduction with internal fixation versus intramedullary nailing treatment higher rates of union with plate fixation and autologous bone grafting than with exchange intramedullary nailing management predicated by type of nonunion (atrophic, hypertrophic, infected) login to view 10 more bullets Malunion varus angulation is common but rarely has functional or cosmetic sequelae risk factors transverse fracture patterns Radial nerve palsy incidence overall incidence of 12.3% ( 8-15%) increased incidence distal one-third fractures (22%) neuropraxia most common injury in closed fractures and neurotomesis in open fractures iatrogenic radial nerve palsy is most common following ORIF via a lateral approach (20%) or posterior approach (11%) spontaneous recovery found at an average of 7 weeks, with full recovery at an average of 6 months risk factors fracture location login to view 1 more bullet fracture type login to view 1 more bullet open fracture treatment observation login to view 8 more bullets surgical exploration login to view 15 more bullets tendon transfers login to view 5 more bullets outcomes overall recovery rate of 88.6% login to view 2 more bullets predictable recovery pattern login to view 2 more bullets