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 Demographics bimodal age distribution young patients with high-energy trauma elderly, osteopenic patients with low-energy injuries Anatomy Osteology humeral shaft is cylindrical distally humerus becomes triangular intramedullary canal terminates 2 to 3 cm proximal to the olecranon fossa Muscles insertion for pectoralis major deltoid coracobrachialis origin for brachialis triceps brachioradialis Nerve radial nerve courses along spiral groove 14cm proximal to the lateral epicondyle 20cm proximal to the medial epicondyle Classification OTA bone number: 1 fracture location: 2 fracture pattern: simple:A, wedge:B, complex:C Descriptive fracture location: proximal, middle or distal third fracture pattern: spiral, transverse, comminuted Holstein-Lewis fracture a spiral fracture of the distal one-third of the humeral shaft commonly associated with neuropraxia of the radial nerve (22% incidence) Presentation Symptoms pain extremity weakness Physical exam examine overall limb alignment 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 Imaging Radiographs views AP and lateral be sure to include joint above and below the site of injury transthoracic lateral may give better appreciation of sagittal plane deformity rotating the patient prevents rotation of the distal fragment avoiding further nerve or soft tissue injury traction views may be necessary for fractures with significant shortening, proximal or distal extension but not routinely indicated Treatment Nonoperative immobilization (coaptation splint followed by a functional brace) indications indicated in vast majority of humeral shaft fractures criteria for acceptable alignment include: < 20° anterior angulation < 30° varus/valgus angulation < 3 cm shortening contraindications absolute severe soft tissue injury or bone loss vascular injury requiring repair brachial plexus injury relative see relative operative indications section radial nerve palsy is NOT a contraindication to functional bracing outcomes 90% union rate increased risk with proximal third oblique or spiral fracture varus angulation is common but rarely has functional or cosmetic sequelae damage control orthopaedics (DCO) closed humerus fractures, including low velocity GSW, should be initially managed with a splint or sling type of fixation after trauma should be directed by acceptable fracture alignment parameters, fracture pattern and associated injuries Operative external fixation (Exfix) indications high energy complex or comminuted fracture open fracture significant soft tissue or bony defect floating elbow hemodynamically unstable polytrauma concomitant vascular injury open reduction and internal fixation (ORIF) indications absolute open fracture vascular injury requiring repair brachial plexus injury ipsilateral forearm fracture (floating elbow) compartment syndrome periprosthetic humeral shaft fractures at the tip of the stem relative bilateral humerus fracture polytrauma or associated lower extremity fracture allows early weight bearing through humerus pathologic fractures burns or soft tissue injury that precludes bracing fracture characteristics distraction at fracture site short oblique or transverse fracture pattern intraarticular extension intramedullary nailing (IMN) indications relative pathologic fractures segmental fractures severe osteoporotic bone overlying skin compromise limits open approach polytrauma Techniques Coaptation Splint & Functional Bracing coaptation splint applied until swelling resolves adequately applied splint will extend up to axilla and over shoulder common deformities include varus and extension valgus mold to counter varus displacement 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 every 3-4 weeks after that External Fixation approaches proximal pins anterolateral surface of proximal humerus mini-open approach with dissection down to bone to mitigate axillary nerve injury distal pins lateral aspect of distal fragment requires mini-open approach with dissection down to bone to mitigate radial nerve injury most distal pin is just proximal to olecranon fossa visualize cortical surface prior to inserting pins Open Reduction and Internal Fixation (ORIF) approaches anterior (brachialis split) approach to humerus used for middle third shaft fractures deep dissection through internervous plane of brachialis muscle lateral fibers (radial n.) and medial fibers (musculocutaneous n.) in majority of patients (~80%) anterolateral approach to humerus used for proximal third to middle third shaft fractures distal extension of the deltopectoral approach radial nerve identified between the brachialis and brachioradialis distally posterior approach to humerus used for distal to middle third shaft fractures although can be extensile triceps may either be split or elevated with a lateral paratricipital exposure radial nerve is found medial to the long and lateral heads and 2cm proximal to the deep head of the triceps radial nerve exits the posterior compartment through lateral intramuscular septum 10 cm proximal to radiocapitellar joint lateral brachial cutaneous/posterior antebrachial cutaneous nerve serves as an anatomic landmark leading to the radial nerve during a paratricipital approach techniques plate osteosynthesis commonly with 4.5mm plate (narrow or broad) 3.5mm plates may function adequately absolute stability with lag screw or compression plating in simple patterns apply plate in bridging mode in the presence of significant comminution postoperative full crutch weight bearing shown to have no effect on union Intramedullary Nailing (IMN) techniques can be done antegrade or retrograde complication nonunion nonunion rates not shown to be different between IMN and plating in recent meta-analyses IM nailing associated with higher total complication rates shoulder pain increased rate when compared to plating (16-37%) functional shoulder outcome scores (ASES scores) not shown to be different between IMN and ORIF nerve injury while controversial, a recent meta-analysis showed no difference between the incidence of radial nerve palsy between IMN and plating radial nerve is at risk with a lateral to medial distal locking screw musculocutaneous nerve is at risk with an anterior-posterior locking screw postoperative full weight bearing allowed and had no effect on union Complications Humeral shaft fx 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 nonounion in closed humeral shaft fractures Malunion varus angulation is common but rarely has functional or cosmetic sequelae risk factors transverse fracture patterns Radial nerve palsy incidence seen in 8-15% of closed fractures 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%) 85-90% of improve with observation over 3 months spontaneous recovery found at an average of 7 weeks, with full recovery at an average of 6 months treatment observation indicated as initial treatment in closed humerus fractures obtain NCS/EMG at ~2 months useful to determine extent of nerve damage, baseline of function, and to monitor recovery wrist extension in radial deviation is expected to be regained first brachioradialis first to recover, extensor indicis is the last surgical exploration indications open fracture with radial nerve palsy (likely neurotomesis injury to the radial nerve) closed fracture that fails to improve over ~4-6 months fibrillations (denervation) seen on EMG tendon transfers indications persistent radial nerve palsy - optimal timing debated wrist extension: PT to ECRB finger extension: FCR/FCU to EDC thumb extension: PL to EPL