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 7 to 11.3 per 100,000 Demographics age 60% occur in patients older than 50 years bimodal age distribution young high-energy trauma peak incidence in third decade of life elderly patients low energy falls osteopenic patients 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 Most common location 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%) most common mechanism motor vehicle accident (~30%) 2nd most common mechanism 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 result of a direct blow to the arm spiral fracture results from a fall onto an outstretched hand or from torsional force distal third humeral shaft fractures result from fall onto a flexed elbow Associated conditions floating elbow fracture of the humeral shaft and the proximal to middle radius and ulna often occurs as a result of a high-energy trauma more common in pediatric patients than in adults ipsilateral shoulder dislocation uncommon injury pattern dislocation is most likely to be a posterior dislocation rather than an anterior dislocation 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 will abduct proximal fragment in fractures occurring proximal to the insertion of the pectoralis major coracobrachialis origin for brachialis triceps brachioradialis Nerve 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 ~7.5cm from the articular surface radial nerve exits the posterior compartment through the lateral intramuscular septum 10 cm proximal to radiocapitellar joint 20cm proximal to the medial epicondyle 14cm proximal to the lateral epicondyle 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 biceps brachii, brachialis, and coracobrachialis vasculature brachial artery and vein nerves musculocutaneous, median, and ulnar nerve posterior compartment muscles triceps nerves radial nerve Classification 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 T: transverse or oblique S: spiral I: intermediate one or two sizable butterfly fragments C: complex three or more butterfly fragments, or significant comminution 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 (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 wrist and thumb interphalangeal joint extension sensation over the dorsum of the hand 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 CT scan may be utilized if there is concern for intra-articular extension CTA may be indicated if there is concern for vascular injury Electromyography (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 indicated in vast majority of humeral shaft fractures criteria for acceptable alignment include: < 20° anterior angulation < 30° varus/valgus angulation < 30° of rotational malalignment < 3 cm shortening relative indications community ambulator noncompliant patients contraindications absolute severe soft tissue injury or bone loss vascular injury requiring repair brachial plexus injury relative see relative operative indications section worsening nerve dysfunction radial nerve palsy is NOT a contraindication to functional bracing outcomes average union rate of 93.5% (77-100%) increased risk with proximal third (54%), and oblique or spiral fracture patterns (23%) average time to union of 10.7 weeks (6.5-22 weeks) average malunion rate of 12% range of motion 38-45% of patients lose external range of motion (5-45 degrees) 88.6% of patients lose less than 10 degrees of shoulder motion 92% lose less than 10 degrees of elbow motion 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 typically utilized as provisional fixation until definitive treatment can be performed, but may be used definitely if needed outcomes average operative time of 30 minutes (18 to 50 minutes) 80% achieve good to excellent outcomes superficial pin track infection rate of 12% open reduction and internal fixation (ORIF) and minimally invasive plate osteosynthesis 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 inability to maintain satisfactory reduction closed progressive nerve deficit after closed manipulation relative bilateral humerus fracture polytrauma or associated lower extremity fracture allows early weight bearing through humerus pathologic fractures typically indicated if life expectancy is greater than 6 months burns or soft tissue injury that precludes bracing fracture characteristics distraction at fracture site segmental fractures short oblique or transverse fracture pattern OTA type A intraarticular extension long oblique proximal humeral shaft fracture large body habitus, obesity, or large breasts radial nerve palsy outcomes significantly lower rates of nonunion and malunion versus nonoperative management average malunion rate of 1% average union rate of 90-92% average time to union of 11.9 weeks improved DASH scores at 6 weeks and 3 months with no significant difference at 12 months compared to nonoperative management intramedullary nailing (IMN) indications relative pathologic fractures segmental fractures severe osteoporotic bone overlying skin compromise limits open approach polytrauma outcomes lower risk of infection (1.2%) than ORIF (5.4%) no significant risk of reoperation (average 11.6%) versus ORIF (average 7.6%) no difference in rates of nonunion with faster time to union (average 10 weeks) than ORIF (average 11.9 weeks) significantly faster operative time (average 61 minutes) than ORIF (average 88 minutes) increased rate when compared to plating (16-37%) greater risk of shoulder impingement postoperatively functional shoulder outcome scores (ASES scores) not shown to be different between IMN and ORIF 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 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 performed in a supine or beach chair position with arm abducted 45° to 60° radial nerve identified between the brachialis and brachioradialis distally protected proximally and distally by the brachialis brachioradialis will protect the musculocutaneous nerve distally cephalic vein and anterior humeral circumflex arteries may be encountered during the surgical approach posterior approach to humerus maybe performed either prone or in a lateral position used for distal to middle third shaft fractures can be extensile allows for exposure from the olecranon fossa to the junction of the proximal and middle third of the humerus triceps may either be split or elevated with a lateral paratricipital exposure triceps split incision through the common tendon of the triceps allows for retraction of the lateral head of the triceps laterally and long head of the triceps medially allows exposure to the radial nerve and profunda brachii artery within the spiral groove lateral brachial cutaneous/posterior antebrachial cutaneous nerve serves as an anatomic landmark leading to the radial nerve benefits avoids the need for ulnar nerve dissection and mobilization can allow for adequate exposure of the humeral shaft fracture limitations 55% of the humeral shaft can be exposed without radial nerve mobilization 76% of the humeral shaft can be exposed with radial nerve mobilization does not utilize a true inter-nervous plane limited proximal extension of the incision triceps sparing or “paratricipital” utilizes lateral and medial windows without disrupting the extensor mechanism lateral brachial cutaneous/posterior antebrachial cutaneous nerve serves as an anatomic landmark leading to the radial nerve during a paratricipital approach lateral window lateral head of the tricep and intermuscular septum allows for identification of the radial nerve, and posterior antebrachial cutaneous nerve medial window mobilization of the ulnar nerve followed by dissection to the medial intermuscular septum border posteriorly benefits minimizes injury to the triceps improved postoperative functional measures decreased risk of denervation of the triceps and anconeus allows for exposure of ~94% of the humeral shaft through the lateral window limitations requires dissection and mobilization of the ulnar nerve for the medial window lateral approach extends from the insertion of the deltoid to the lateral epicondyle allows for exposure of the distal two-thirds of the humerus the interval is between the lateral intermuscular septum and the triceps radial nerve identified proximal to the deep head of the triceps and mobilized by releasing the lateral intermuscular septum higher risk of iatrogenic radial nerve injury medial approach primarily used to access the brachial artery, median nerve, and ulnar nerve rarely used for fracture fixation incision extends from the proximal medial margin of the biceps distally to the medial epicondyle ulnar nerve is retracted posteromedially median nerve and brachial artery retracted anterolaterally minimally invasive plate osteosynthesis proximal and distal incisions performed through an anterolateral approach followed by the creation of an extraperiosteal tunnel the plate is tunneled and positioned under fluoroscopic guidance Minimizes surgical dissection, but increases the risk of radial nerve injury due to lack of direct visualization techniques plate osteosynthesis commonly with narrow or broad, 3.5mm or 4.5mm dynamic compression plate or limited contact dynamic compression plate dynamic compression plate allows for staggered screws narrow dynamic compression plate better accommodates patients with a more narrow humerus limited contact dynamic compression plate provide benefit of being easier to contour, decreased stress shielding, and preservation of periosteal blood supply 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 antegrade performed supine 3cm incision over the anterolateral edge of the acromion down the deltoid, which is then split to identify the rotator cuff entry site for the nail through the supraspinatus fibers as medial as possible to apex of the humeral head retrograde performed prone or lateral through a posterior incision over the posterior supracondylar cortex avoid reaming across the fracture site to prevent radial nerve injury 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 nerve injury radial nerve at risk with a lateral to medial distal locking screw while controversial, a recent meta-analysis showed no difference between the incidence of radial nerve palsy between IMN and plating musculocutaneous nerve at risk with an anterior-posterior locking screw axillary nerve at risk with proximal locking screws in antegrade nails anterior and posterior humeral circumflex vessels are also at risk 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 supraspinatus at risk with antegrade nails due to the avascular nature of the supraspinatus tendon at its insertion site near the greater tuberosity entry portal should be created near the musculotendinous junction entry portal should not be greater than 1cm 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 1: absent callus 2: present, nonbridging callus 3: present, bridging callus score ≥8 - 86% NPV for nonunion score <8 - 65% PPV risk factors humeral shaft fractures treated nonoperatively dependent on fracture pattern OTA type A (15.4 to 29%) > type B (4%) >type C (0%) fractures 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) atrophic nonunion debridement and curretage of non-viable fragment and fibrous scar at fracture site intramedullary nail revision with reaming and exchange to larger nail ream up by at least 1mm to improve biomechanical stability compression plating with bone grafting iliac crest graft, femoral autograft from REA (reamer/irrigator/aspirator) bone graft subsititue hypertrophic nonunion intramedullary nailing with exchange for larger nail locked angle plating 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 distal third (56.9%) > middle third (41.5%) > proximal third (1.5%) fracture type transverse (21.2%) > spiral (19.8%) > oblique (8.4%) > comminuted (6.8%) open fracture treatment observation indicated as initial treatment in closed humerus fractures approximately 77.2% with spontaneous radial nerve recovery 85-90% of these will recovery within the first 3 months obtain NCS/EMG at ~2 months useful to determine the 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 may require debridement or removal or incarcerated fragments, nerve grafting, or nerve transfers at the time of exploration outcomes radial nerve appearance at the time of exploration nerve in continuity (62.7%) lacerated (26.8%) incarcerated within the fracture site (10.5%) timing of exploration early exploration (within three weeks of injury) recovery rate ~90% late exploration (eight weeks or more out from injury) recovery rate ~68% 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 outcomes overall recovery rate of 88.6% primary nerve palsy recovery rate - 88.2% iatrogenic/secondary nerve palsy recovery rate - 93.9% predictable recovery pattern brachioradialis and extensor carpi radialis longus are first to recover extensor pollicus longus and extensor indicis proprus are last to recover