Midshaft humerus fractures in adults

INTRODUCTION — 

Fractures of the humerus can occur proximally, at the shaft, or distally. The majority of both proximal and midshaft humerus fractures are nondisplaced and can be treated conservatively (nonsurgically).

Nonstress fractures of the midshaft (diaphysis) of the humerus in adults are reviewed here. Stress fractures of the humeral shaft and proximal humeral fractures are discussed separately, as are humeral fractures in children.

●Adult humerus fractures (see "Stress fractures of the humeral shaft" and "Proximal humeral fractures in adults" and "Elbow fractures and dislocation in adults")

●Child humerus fractures (see "Midshaft humeral fractures in children" and "Proximal humeral fractures in children" and "Orthopedic aspects of child abuse")

CLINICAL ANATOMY — 

The humerus is the largest bone in the upper extremity. The proximal humerus articulates with the glenoid of the scapula to form the shoulder joint (figure 1). The muscles and tendons of the rotator cuff, the acromion, and ligamentous attachments such as those between the coracoid process of the scapula and the acromion serve to both stabilize the glenohumeral articulation and provide for a wide range of motion of the shoulder joint (figure 2 and figure 3). The distal humerus articulates with the radius and ulna at the elbow (figure 4). (See "Evaluation of the adult with shoulder complaints", section on 'Anatomy and biomechanics' and "Evaluation of elbow pain in adults", section on 'Clinical anatomy'.)

The greater tuberosity, located lateral to the humeral head and on the superior aspect of the humerus, provides the attachment for three of the rotator cuff muscles: supraspinatus, infraspinatus, and teres minor (figure 5). The lesser tuberosity of the humerus is located on the anterior surface of the humerus and provides the attachment for the subscapularis muscle (figure 6). For the purposes of fracture classification, the lesser tuberosity marks the boundary between the proximal humerus and the midshaft.

The humeral shaft supplies the attachment for a number of powerful muscles (figure 7). The pectoralis major muscle inserts on the proximal shaft while the deltoid muscle attaches to the midshaft. The biceps brachii and triceps muscle groups attach further distally.

The tendon of the long head of the biceps brachii muscle passes between the lesser and greater tuberosities as it courses from its origin on the superior portion of the glenoid to its insertion on the radius (figure 8).

The blood supply to the humeral shaft is supplied by the axillary and brachial artery; the latter branches to form the radial and ulnar artery (figure 9 and figure 10 and figure 11). The vascular supply can be disrupted if there is considerable displacement of shaft fragments.

Innervation of the muscles in the posterior compartment of the arm and forearm is provided by the radial nerve. The radial nerve enters the arm medial to the humerus and anterior to the long (medial) head of the triceps muscle and travels inferolaterally, moving around and adjacent to the humeral shaft, in the radial groove (figure 12 and figure 10). Thus, the radial nerve is susceptible to injury when there is significant displacement of mid- to distal humeral shaft fractures [1]. Median (figure 13) and ulnar (figure 14) nerve injuries are uncommon complications of such fractures [2].

EPIDEMIOLOGY AND RISK FACTORS — 

Midshaft humeral fractures account for about 2 percent of all fractures [3]. They occur in all age groups but show a bimodal distribution: The first peak is seen in the third decade in males and is often associated with high-velocity trauma; the second peak is noted in females in the seventh decade and is associated with low-velocity falls [1,4,5]. An observational study of 401 humeral shaft fractures noted that 68 percent resulted from a simple fall, and 90 percent overall were due to trauma [1]. Trauma, increasing age, and osteoporosis are known risk factors. (See "Falls in older persons: Risk factors and patient evaluation" and "Falls: Prevention in community-dwelling older persons".)

MECHANISM OF INJURY — 

Midshaft fractures typically result from trauma such as a direct blow or bending force to the humerus and, less commonly, from a fall onto an outstretched hand or elbow [4-6]. Midshaft fractures may also result from strong muscle contractions such as in high-velocity throwing or arm wrestling [7,8]. There is some debate whether this occurs solely from a violent muscle contraction or requires an underlying stress fracture associated with the muscle contraction. A study of 90 recreational baseball players with midshaft humeral fractures concluded that these fractures are caused by the accelerated phase of throwing and can occur in any recreational baseball player who tries to make a hard throw.

CLINICAL PRESENTATION AND EXAMINATION FINDINGS — 

Patients with midshaft humeral fractures typically present with severe arm pain in the area of the mid-arm but may have referred pain to the shoulder or elbow. Swelling and ecchymosis are often apparent shortly after the injury. The presence of abrasions or lacerations should be noted. If medicolegal circumstances warrant and the patient agrees, photographs of the injured arm can be obtained.

There is significant tenderness to palpation, and crepitus may be noted at the fracture site. Shortening of the upper arm suggests the presence of significant humeral shaft displacement. Careful examination, including inspection and palpation of the shoulder and elbow, are important to assess for other injuries.

The initial evaluation of midshaft humerus fractures includes a detailed neurovascular examination of the affected arm, including careful assessment of the radial and ulnar arteries and the function of the radial, median, and ulnar nerves.

Examination of peripheral nerves

●Radial nerve – The radial nerve is the nerve most commonly injured by midshaft humerus fractures. Injury to the radial nerve results in weakness of wrist, finger, and thumb extension and some weakness of elbow supination. Motor function can be tested by giving the "thumbs up" sign (picture 1) and testing resisted extension of the thumb (picture 2), fingers, or wrist. Sensory loss may be present on the dorsum of the hand and is easily tested at the dorsal web space between the thumb and index finger.

●Median nerve – Injury to the median nerve is uncommon following midshaft humeral fractures but, when it occurs, results in weakness of the flexor muscles of the hand and loss of sensation on the palmar surface of the thumb and the index and middle fingers. The largest branch and most commonly injured portion of the median nerve is the anterior interosseus nerve. It lacks a sensory component and results in loss of hand and finger flexion. This is best evaluated by having the patient give an "OK" sign, which tests the flexor pollicis longus (thumb flexion) and flexor digitorum profundus (distal interphalangeal flexion of the index finger) (picture 3). Anterior interosseus syndrome results in weakness or flattening of the "OK" sign due to loss of thumb and index finger flexion (picture 4).

●Ulnar nerve – The ulnar nerve is seldom injured by midshaft humeral fractures. Injury to the ulnar nerve results in dysfunction of the dorsal and palmar interossei and an inability to abduct and adduct the fingers. This can be tested by asking the patient to make the "peace sign" (picture 5) and testing the strength of the interossei (picture 6).

DIAGNOSTIC IMAGING

Approach to imaging — Radiographs of the entire humeral shaft in the anteroposterior and lateral planes are necessary to evaluate the degree of angulation or displacement of any fracture. Initial shoulder radiographs should include at least one view (axillary (image 1) or scapular-Y (image 2)) that assures that the humeral head is not dislocated. If physical examination cannot exclude injury to the shoulder and elbow, radiographs should include those joints as well.

Ultrasound may be used initially at the sideline or hospital to determine if a fracture is present pending diagnostic plain radiographs. A negative ultrasound study does not rule out a fracture. In addition, diagnostic ultrasound may be helpful for evaluating the condition of the radial nerve. (See 'Radial nerve injury' below.)

Fracture patterns — Fractures of the humeral shaft can be spiral, oblique, or transverse. The AO North American classification system sorts each fracture into three lettered categories (figure 15):

●A - Simple fractures (image 3)

●B - Wedge fractures (image 4)

●C - Complex (comminuted) fractures

Depending on the location of the fracture, displacement of the proximal and distal fragments can occur.

●Fractures near the midpoint of the humeral shaft typically assume an apex lateral position. The proximal fragment is pulled laterally by the deltoid, while the distal fragment is pulled medially by the triceps and biceps. Fractures near the midpoint of the shaft are more likely than more proximal or distal fractures to shorten due to the strong pull of the biceps and triceps muscles.

●Shaft fractures that are located more proximally are angulated apex medially due to the medial pull of the pectoralis major muscle proximally and the lateral pull of the deltoid muscle distally.

ORTHOPEDIC CONSULTATION OR REFERRAL

Indications for surgical referral — Immediate surgical referral is required for a midshaft humerus fracture associated with vascular injury and for open fractures. In all cases of midshaft humerus fracture, it is reasonable to obtain orthopedic consultation.

Other absolute indications for referral include:

●Fracture associated with articular injuries

●Brachial plexus injuries

●Ipsilateral forearm fractures (eg, floating elbow)

●Bilateral humerus fractures

●Pathologic fractures (eg, associated with bone tumor)

●Concomitant traumatic major nonhumeral fractures (eg femur fracture)

●High-velocity gunshot injuries (depending on the extent of injury, may require immediate surgical consultation)

●Fracture associated with severe soft tissue injuries or significant skin involvement [9]

Referral is not required for an isolated radial nerve injury in an otherwise stable, uncomplicated fracture without other indications for referral. The great majority of radial nerve palsies are transient and resolve in a matter of weeks. (See 'Radial nerve injury' below.)

Acceptable positioning for a midshaft humerus fracture includes [10-12]:

●Less than 20 degrees of anterior or posterior angulation.

●Less than 30 degrees of varus angulation. Varus angulation of up to 10 degrees is common [13].

●Less than 3 cm of shortening.

●Less than 15 degrees of rotational deformity.

Fractures that exceed the limits of acceptable alignment either at the initial evaluation or at any time during follow-up for nonoperative management should be referred to orthopedic surgery for closed reduction or operative stabilization.

Displaced distal spiral shaft fractures (Holstein Lewis fractures) have a high association with radial nerve injury and are generally best referred for surgical evaluation and possible exploration and repair [14].

Other relative indications for referral include:

●Transverse fractures that are relatively unstable and at a high risk of shortening

●Patient noncompliance

●An obese body habitus that may result in increased varus deformity

Surgery versus bracing — Debate continues about the best management approach for midshaft humerus fractures. We suggest evaluating patients on a case-by-case basis and obtaining orthopedic consultation for patients who are reasonable surgical candidates and express a preference or desire to learn more about surgical options. Treatment will depend upon the patient's preferences and values, including the relative importance of regaining function sooner compared with the risk of nonunion and surgery-related complications. In practice, younger and more active patients, including laborers seeking an early return to work, often opt for surgical management. Functional bracing is more appropriate for high-risk surgical candidates, frail older adults, and others wishing to avoid surgery.

Traditionally, the preferred treatment for midshaft humerus fractures has been nonoperative management with functional bracing. This approach allows for adequate bone healing and good functional outcomes in most cases while avoiding risks associated with surgery, such as infection, radial nerve injury, and implant failure requiring revision surgery. More recent studies have reported that surgical treatment results in superior rates of fracture union, less frequent need for additional procedures, and greater overall cost-effectiveness than nonoperative management, although radial nerve injury continues to be more common with surgery [13-16]. Longer-term functional outcomes are similar regardless of treatment [13]. (See 'Results with functional bracing' below and 'Radial nerve injury' below.)

A systematic review of five randomized trials, of which four were included in a meta-analysis (n = 292 patients), reported that surgery was associated with a lower risk of nonunion (0.7 versus 15.7 percent, odds ratio 0.13 [95% CI 0.03-0.52]) and lower rates of reintervention (1.4 versus 19.3 percent, odds ratio 0.14 [95% CI 0.02-0.92]) [13]. Transient radial nerve injury was more common in the surgical group (17 versus 0.7 percent, odds ratio 8.23 [95% CI 1.62-41.77]). At one year, there were no clinically significant differences in functional outcomes.

A five-year follow-up to the FISH randomized trial comparing functional bracing versus surgery reported comparable functional outcomes at five years [17]. However, functional bracing produced inferior functional outcomes at one- and two-year follow-up, and 32 percent of patients required secondary surgery [18].

Studies of cost effectiveness suggest that surgical treatment is superior to nonoperative treatment due to delays in return to function and work and the increased need for reintervention [16].

Surgical options — Surgical treatment options include intramedullary (IM) nailing, open reduction and plate osteosynthesis (ORPO), minimally invasive plate osteosynthesis (MIPO), and compression plating. IM nailing involves a smaller incision and less risk of infection or injury to soft tissues, vascular structures, and the radial nerve [14,15]. However, malunion and nonunion rates are higher, and satisfaction rates are lower.

Surgical plating with ORPO or MIPO has the highest rates of bony union, lowest need for revision surgery, and highest functional scores but is associated with higher rates of radial nerve injury and infection [14,15]. MIPO is associated with fewer infections and episodes of radial nerve palsy compared with more open procedures, and it results in the best functional outcome scores.

An extensive systematic review of controlled and observational studies (n = 173, 11,868 patients) reported higher fracture healing rates with surgery (96 percent for plating groups, 94 percent for IM nailing) compared with functional bracing (89 percent) [15]. Plating was associated with the best functional outcomes. Radial nerve injury occurred most often in patients treated with open plating (7 percent) compared with other surgical approaches (minimally invasive procedures 4 percent, IM nailing 4 percent) and seldom occurred in patients treated with bracing (1 percent). (See 'Radial nerve injury' below.)

INITIAL MANAGEMENT

General approach and initial interventions — Humeral shaft fractures can be treated initially in a functional brace with a cuff and collar sling that allows for gravity-based traction (figure 16). If a brace is not available or not feasible due to pain and swelling, a plaster coaptation (proximal sugar tong) splint (picture 7 and figure 17) can be applied with a cuff and collar sling (figure 16). (See 'Functional bracing' below.)

The splint is applied to the medial aspect of the upper arm starting at the upper portion of the axilla and extended down around the elbow, up past the deltoid and over the top of the shoulder past the acromion. Slight valgus molding of the splint can decrease varus malalignment. Ensuring the splint extends deep into the axilla, proximal to the fracture sight also helps to minimize varus angulation. Avoid multiple folds ("bunching up") of the plaster or fiberglass in the axilla as this may cause a burn injury [19]. (See "Basic techniques for splinting of musculoskeletal injuries", section on 'Sugar tong splints'.)

General acute fracture care, including analgesia, is reviewed in detail separately. (See "General principles of acute fracture management".)

Functional bracing — When surgery is not to be performed, a functional brace is the preferred nonoperative treatment for humerus shaft fractures. The brace can be applied once initial swelling has resolved (typically after one to two weeks). Prefabricated braces of various sizes (eg, Sarmiento brace) can be used (picture 8A-B).

Typically, biceps circumference is used to determine the appropriate brace size, but manufacturer instructions should be followed closely. The lateral portion of the brace often extends from the top of the shoulder to one to two centimeters above the elbow. The inner, or medial, portion of the brace extends from the elbow to just below the axilla. The brace should be applied tightly, but without obstructing blood flow or causing skin breakdown, and should extend over the entire fracture site. Compression around the fracture site can restore proper positioning and may stimulate early osteoblastic activity [20]. A cuff and collar sling can be used if some degree of traction is necessary (figure 16).

If adequate alignment is not obtained in a functional brace with a cuff and collar, the patient should be referred to an orthopedic surgeon. (See 'Indications for surgical referral' above.)

Hanging cast — Although rarely done, patients with poorly aligned fractures who are not surgical candidates may be treated with a hanging cast. Application of a hanging cast (figure 18) is similar to that for a long arm cast. The elbow is placed in 90 degrees of flexion and the forearm in a neutral position. The proximal portion of the cast extends 2 cm above the fracture site. The cast should be hung from the neck to the distal forearm with the elbow left unsupported at all times. The weight of the cast should be no more than two pounds, which is equivalent to one made from three 4-inch (10 cm)-wide and one 3-inch (7.5 cm)-wide rolls of plaster [21].

Adjustments to the length of the neck strap and the distal attachment points can be made to adjust for angulation. To provide traction or sufficient force to reduce fracture angulation, the hanging cast must be unsupported except at the attachment point, and the patient must be upright at all times. This means sleeping in an upright position.

A hanging cast may be molded to help reduce apex medial, lateral, anterior, or posterior angulation if there is minimal swelling and the patient can be relied upon to watch for symptoms and signs of constriction by the cast or the appearance of compartment syndrome.

FOLLOW-UP CARE

Follow-up visit schedule — The first follow-up visit for patients managed nonoperatively should occur 7 to 10 days after the initial evaluation. Anteroposterior (AP) and lateral plain radiographs should be obtained to evaluate fracture alignment. Examination should include inspection of the skin for possible breakdown and assessment of radial nerve function. If not already done, patients should be placed in a functional brace.

Fractures with borderline alignment (ie, close to a threshold for surgical referral) should be reassessed weekly to ensure alignment remains acceptable and the fracture stable. Repeat radiographs are performed at each visit. Fractures generally achieve stability in three to four weeks (see 'Indications for surgical referral' above). Patients managed initially in a hanging cast can be switched to a functional brace once alignment is acceptable and some callous formation is present on plain radiograph.

Patients with fractures with acceptable alignment can follow up every three to four weeks until healing is complete. At each visit, AP and lateral plain radiographs should be obtained and the skin and neurovascular status of the injured extremity reassessed. Typical healing time is 10 to 16 weeks [15,21].

Rehabilitation — Rehabilitation may begin within one week of injury. Patients can begin with gentle pendulum exercises (picture 9) and passive supine range of motion exercises to maintain glenohumeral mobility and reduce the risk of frozen shoulder. Pain determines the timing for introducing additional exercises for shoulder motion, but simple isometric and active strength exercises are generally begun within three to four weeks. Physical therapy typically includes exercises for the upper extremity, scapula, and cervical spine.

Gradually, more demanding exercises are begun to maintain or improve shoulder, elbow, wrist, and hand mobility and to strengthen the muscles of the injured limb. Introduction of such exercises is determined on the basis of pain and fracture stability. In most patients, the functional brace can be removed once callous formation is present. After brace removal, the patient is re-evaluated every three to four weeks until adequate range of motion and strength is achieved.

Results with functional bracing — The decision of whether to treat midshaft humerus fractures surgically or nonoperatively is reviewed above. (See 'Surgery versus bracing' above.).

In the large majority of cases, fractures managed in a functional brace heal well and without clinically significant complications, according to abundant, largely observational evidence. There appear to be no clinically significant differences in long-term functional outcomes between patients treated successfully in a functional brace and those managed surgically [13,14,17].

An extensive systematic review of controlled and observational studies (n = 173, 11,868 patients) reported that 89 percent of midshaft humerus fractures healed completely in an average of 16 weeks when managed in a functional brace [15]. The rate of nonunion was 11 percent and malunion 6 percent. A systematic review limited to randomized trials reported a slightly higher nonunion rate of approximately 15 percent but found that approximately 20 percent of braced patients required surgical revision [13].

COMPLICATIONS — 

The most common complications associated with humeral shaft fractures are neurovascular compromise, particularly radial nerve injury, and malunion or nonunion. Skin breakdown may occur with bracing, and infection can occur postoperatively. General fracture complications are described separately. (See "General principles of fracture management: Early and late complications".)

Radial nerve injury — Radial nerve injury is the most common neurologic complication of humeral shaft fracture. Such injury typically presents with paresthesias of the dorsal hand or weakness in wrist and finger extension (figure 12).

The incidence of primary radial nerve palsy (directly caused by the initial trauma) varies widely across studies, ranging from 1 to 25 percent [22-24]. Factors associated most closely with radial nerve injury include high-energy trauma and concomitant vascular injury [23-25]. Nerve injury is more likely to involve a spiral fracture or fracture involving the distal or middle third of the humeral shaft. Studies suggest that over 90 percent of patients begin recovering radial nerve function within seven to nine weeks, and the rate of recovery generally does not improve with surgical exploration [23,26].

The incidence of secondary radial nerve palsy that develops during treatment with functional bracing is estimated to be 0.4 to 1 percent [15,23,26]. The incidence of secondary radial nerve palsy associated with surgery is 3 to 7 percent, depending on the procedure [15,23,26]. The incidence with open plating is approximately 7 percent, with intramedullary nailing 6 percent, and with minimally invasive plating 3 percent [15,27]. Recovery rates for secondary radial nerve palsy are similar across causes, with reports ranging from 89 to 94 percent of patients regaining radial nerve function [23,26,28].

Patients requiring surgical intervention for nonunion may be more likely to develop persistent deficits in nerve function following repair. In a multicenter, observational study of 379 patients, the incidence of nerve palsy was 6.9 percent (n = 26), with deficits persisting in 15.8 percent of those patients (n = 4) at 12 months [29]. Nerve injury was more common if the fracture involved the middle third of the humerus.

Diagnostic ultrasound may be helpful in evaluating radial nerve injuries and determining which may be amenable to surgical intervention. Signs of more severe nerve injury or entrapment on ultrasound correlate closely with operative findings in observational studies, and such injury may benefit from surgical exploration, whereas findings consistent with neuropraxia suggest the nerve will recover spontaneously [30-32].

Nonunion and malunion — Nonunion of humeral shaft fractures may be present if there is no radiographic evidence of bony union at three to six months [10]. Symptoms of nonunion include continued pain and swelling. Nonunion occurs more commonly in transverse and severely comminuted fractures. Malunion (fracture heals but with a deformity) may also occur. All patients with suspected nonunion or malunion require referral to an orthopedic surgeon. Acceptable degrees of angulation and rotation are defined above. (See 'Orthopedic consultation or referral' above.)

Systematic reviews report nonunion rates of 11 to 16 percent in midshaft fractures treated with functional bracing and 0.7 to 3 percent in those treated initially with surgery [14,15,17,22,33]. Malunion is reported to occur in 6 to 10 percent of midshaft fractures treated with functional bracing and 1 to 3 percent of those treated surgically [13-15,22].

RECOMMENDATIONS FOR RETURN TO SPORT OR WORK — 

Returning to work that is amenable to wearing a functional brace typically can be done with adequate pain control two weeks following the injury. Patients whose jobs require use of both arms or involve heavy lifting can return to work once pain is controlled, range of motion and strength are regained, and there is evidence of healing on radiograph.

Patients typically cannot return to sport until 8 to 12 weeks following the injury when healing is complete [21]. Evidence of complete healing on radiograph is required before a patient can resume contact sports. While the fracture heals, patients may perform low-impact activity, such as stationary bicycling, to maintain cardiovascular fitness.

ADDITIONAL INFORMATION — 

Several UpToDate topics provide additional information about fractures, including the physiology of fracture healing, how to describe radiographs of fractures to consultants, acute and definitive fracture care (including how to make a cast), and the complications associated with fractures. These topics can be accessed using the links below:

●(See "General principles of fracture management: Bone healing and fracture description".)

●(See "General principles of fracture management: Fracture patterns and description in children".)

●(See "General principles of definitive fracture management".)

●(See "General principles of acute fracture management".)

●(See "General principles of fracture management: Early and late complications".)

SOCIETY GUIDELINE LINKS — 

Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Fractures of the skull, face, and upper extremity in adults" and "Society guideline links: Acute pain management".)

SUMMARY AND RECOMMENDATIONS

●Mechanism – Humerus shaft fractures occur most often in young adult males from high-velocity trauma and in older adult females from low-velocity falls. The mechanism generally involves a direct blow or bending force applied to the upper arm. (See 'Epidemiology and risk factors' above and 'Mechanism of injury' above.)

●Clinical evaluation and diagnostic imaging – Initial evaluation includes assessment of skin integrity, neurovascular function (especially radial nerve (picture 1 and picture 2)), deformity, and shortening. Patients typically present with severe pain in the mid-arm region but may have referred pain to the shoulder or elbow. Swelling and ecchymosis are often apparent. (See 'Clinical presentation and examination findings' above.)

Initial imaging should include plain radiographs of the entire humeral shaft in the anteroposterior and lateral planes and at least one view (axillary (image 1) or scapular-Y (image 2)) that assures that the humeral head is not dislocated. (See 'Diagnostic imaging' above.)

●Indications for orthopedic referral – Immediate surgical referral is required for a midshaft humerus fracture associated with vascular injury and for open fractures. In all cases of midshaft humerus fracture, it is reasonable to obtain orthopedic consultation. (See 'Orthopedic consultation or referral' above.)

Other absolute indications for referral include:

•Fracture associated with articular injuries

•Brachial plexus injuries

•Ipsilateral forearm fractures (eg, floating elbow)

•Bilateral humerus fractures

•Pathologic fractures (eg, associated with bone tumor)

•Concomitant traumatic major non-humeral fractures (eg femur fracture)

•High-velocity gunshot injuries (depending on the extent of injury, may require immediate surgical consultation)

•Fracture associated with severe soft tissue injuries or significant skin involvement

●Management – Initial immobilization is usually accomplished with a coaptation (sugar-tong) splint applied to the upper arm along with a collar and cuff sling (picture 7). (See 'Initial management' above.)

The best definitive management for midshaft humerus fractures is debated. Patients who are reasonable surgical candidates and express a preference or desire to learn more about surgical options should be referred. (See 'Orthopedic consultation or referral' above.)

For most healthy patients with a midshaft humerus fracture, we suggest surgical repair rather than nonsurgical treatment (Grade 2B). However, high-risk surgical candidates or patients who prioritize avoidance of surgery over a more rapid recovery may reasonably opt for nonsurgical treatment (ie, a functional brace). (See 'Surgery versus bracing' above.)

In practice, younger and more active patients, including laborers seeking an early return to work, often opt for surgical repair, while high-risk surgical candidates, frail older adults, and others wishing to avoid surgery opt for nonsurgical treatment. Isolated, uncomplicated humerus shaft fractures without excessive angulation or displacement can be treated nonsurgically in a functional brace.

●Follow-up care for patients treated with bracing – After initial swelling has resolved (typically after one to two weeks), a commercial, functional brace can be used for definitive immobilization until adequate callous formation is apparent radiographically and the fracture is stable to manual stress, typically at 10 to 16 weeks. Schedules for follow-up visits are included in the text. (See 'Functional bracing' above and 'Follow-up care' above.)

Rehabilitation begins within a week of injury and begins with gentle pendulum exercises to maintain mobility and help prevent frozen shoulder. Once the brace is removed, the patient may begin more vigorous exercises to strengthen arm and shoulder muscles and restore range of motion.

●Complications – Radial nerve injury is the most common neurologic complication and occurs more often with surgical treatment. Such injury typically presents with paresthesias of the dorsal hand or weakness in wrist and finger extension (figure 12). Over 90 percent of patients begin recovering radial nerve function within seven to nine weeks, and the rate of recovery generally does not improve with surgical exploration. (See 'Complications' above.)

Nonunion and malunion can occur. Symptoms of nonunion include persistent pain and swelling.

●Return to activity – Return to sport or work that involves full use of the arm is expected in 8 to 12 weeks but should not occur until callus is present, the fracture site is stable to manual stress, and range of motion has been restored. Patients generally can return to work that does not require use of the arm and is amenable to a functional brace within one to two weeks. (See 'Recommendations for return to sport or work' above.)