Midshaft Humerus Fractures


Background

Fractures of the humeral shaft account for approximately 3% of all fractures. [12 Traditionally, humeral shaft fractures have been described according to the following features [2:

  • Location - Proximal, middle, or distal
  • Type of fracture line - Transverse, oblique, spiral, comminuted, or segmental
  • Open or closed status

This article focuses on midshaft humerus fractures.

No classification scheme for humeral shaft fractures has gained universal acceptance, though the system developed by the Orthopaedic Trauma Association (OTA) and the Arbeitsgemeinschaft für Osteosynthesefragen (AO) is often employed (see Classification).

Although most fractures of the humeral shaft are inherently unstable, nonoperative treatment remains the standard. [3For operative candidates, the role of surgery, as well as which type of surgery is appropriate, is dependent on the patient and the fracture characteristics. [45]

For patient education resources, see the First Aid and Injuries Center, as well as Broken Arm.

Anatomy

The humeral shaft is the area extending from the upper border of the pectoralis major tendon to the supracondylar ridge. The proximal half is almost cylindrical, whereas distally, the anteroposterior diameter narrows into a prismatic shape. The posterior surface (between the medial and lateral borders) is the largest. The radial sulcus, which contains the radial nerve and, at its midpoint, the nutrient foramen, crosses the posterior middle third of the humerus.

The large muscles that surround the humerus prevent direct palpation. The arm is divided into anterior and posterior compartments by two intermuscular septa: medial and lateral. [6The anterior compartment contains the following:

  • Biceps brachii, coracobrachialis, and brachialis
  • Brachial artery and vein
  • Median, musculocutaneous, and ulnar nerves

The posterior compartment contains the following:

  • Triceps
  • Radial nerve

Prognosis

Each method of humeral shaft fracture treatment is associated with a union rate of higher than 90%. Each fracture must be considered separately and treated accordingly. [7]

Connolly et al assessed the outcome of immediate open reduction and internal fixation (ORIF) in 46 patients with open humeral diaphyseal fractures. [8 All fractures united primarily in satisfactory angulation of less than 5º in coronal and sagittal planes. In 40 patients, mean time to union was 18.4 weeks; in six, union was delayed (mean time to union, 42.5 weeks). No patient required subsequent surgery to obtain union. Complications were rare (including amputation in three patients and dysesthesia in one), with no deep infections, nonunions, or iatrogenic nerve injuries. Two implants were removed because of discomfort.

Heineman et al conducted a meta-analysis of four trials comparing treatment of humeral shaft fractures with different implants (plates and nails). [9 After calculating the data from the four trials (203 patients), they did not find any statistically significant differences between plates and nails with respect to complications, nonunion, infection, nerve palsy, or reoperation.

In a retrospective study, Pretell et al reported that 17 of 19 patients with fractures of the humeral shaft treated with anterograde locked intramedullary nailing were satisfied with the results. [10 The mean duration of hospitalization after surgery was 4.3 days; there were no complications related to the implants; there were no operative complications; and the average operation time was 48 minutes. The consolidation rate was 80%.

In a systematic review and meta-analysis of the clinical outcomes and pooled complication rate for the use of Surgical Implant Generation Network (SIGN) intramedullary nails in femoral (60%), tibial (38%), and humeral (2%) fracture fixation, all studies that measured clinical outcome indicated that more than 90% of patients achieved full weightbearing status, favorable range of motion (ROM; >90º), or radiographic or clinical union. [11The overall complication rate was 5.2%; malalignment (>5º angulation in any plane) was the most common complication (7.6%), followed by delayed union or nonunion (6.9%), infection (5.9%), and hardware failure (3.2%).

A 6-year observational cohort study of 95 patients with humeral fractures (20 proximal, 75 diaphyseal) treated with antegrade intramedullary nailing documented improvements in functional recovery for all patients over time but noted better outcomes in patients younger than 65 years. [12Fracture type and patient gender had no effect on these results at 1 month and 6 months. No infections occurred. Eighteen patients required blood transfusions, and 10 required revision surgery.




History and Physical Examination

Patients with humeral shaft fractures present with arm pain, deformity, and swelling. The arm is shortened, with motion and crepitus on manipulation. A careful neurovascular evaluation of the limb must be documented, because the incidence of radial nerve injuries is approximately 16%. [13If indicated, Doppler pulse and compartment pressures should be checked. [1415]

Classification

The Orthopaedic Trauma Association (OTA) and the Arbeitsgemeinschaft für Osteosynthesefragen (AO) developed a system of classification applicable to humeral shaft fracture. This system was first published in 1996 and was subsequently revised in 2007 and 2018. [16In the current classification, humeral shaft fractures would first be labeled by the number of the bone or bone segment involved (12 in the case of the humeral diaphysis) and then be divided into the following three main types:

  • Type A - Simple fractures
  • Type B - Wedge fractures
  • Type C - Multifragmentary fractures

Each of these main type is divided into groups.

For type A (simple) fractures, the groups are determined by the angle of the fracture and consist of spiral fractures (A1), oblique (≥30º) fractures (A2), and transverse (< 30º) fractures (A3). The location of the fracture (proximal third, middle third, or distal third) is specified. 

Type B (wedge) fractures are divided into intact wedge fractures (B2) and fragmentary wedge fractures (B3). The location of the fracture (proximal third, middle third, or distal third) is specified.

Type C (multifragmentary) fractures are divided into intact segmental fractures (C2) and fragmentary segmental fractures (C3). Type C3 fractures are also subdivided on the basis of location (proximal diaphyseal–metaphyseal, pure diaphyseal, or distal diaphyseal–metaphyseal).

More detailed descriptions of these fractures may be achieved by using one or more "universal modifiers," which may be appended to the fracture code. Further information on the current AO/OTA classification is available on the AOTrauma Web site.



Imaging Studies

Anteroposterior (AP) and lateral radiographs should be obtained first. These should be taken at 90º angles to each other. To obtain these radiographs, move the patient rather than rotate the injured limb through the fracture site. The shoulder and elbow should be included on each radiograph. Traction radiographs may be helpful with comminuted or severely displaced fractures, and comparison radiographs of the contralateral side may be helpful for determining preoperative length. [2 (See the image below.)

Diaphyseal humerus fracture. Diaphyseal humerus fracture.

Computed tomography (CT) is rarely indicated.


Approach Considerations

Surgical treatment of humeral shaft fractures should be considered for multiple reasons. One indication for surgery is an inability to maintain the fracture in adequate alignment using closed methods. Factors that can account for this inability include the following:

  • Fracture pattern - Displaced, comminuted, or segmental (segmental fractures are at risk of nonunion at one fracture site or at both of them) [17]
  • Prolonged recumbency or an inability to maintain a semisitting or reclined position, as in a patient with multiple traumatic injuries
  • Noncompliance

Ipsilateral fracture of the ulna or radius is another indication for surgery, necessitating stabilization of the humeral and forearm fractures to allow early range of motion (ROM). [1318If the patient has bilateral humeral fractures, one or both should be fixed to allow patient self-care. [2Operative indications also include open fractures, existing or impending pathologic fractures, and fractures associated with a vascular injury that requires repair.

An area of controversy is the occurrence of new-onset radial nerve injuries after closed manipulation. Such injuries were once thought to be indications for surgery; however, this assumption has been called into question. Spinal cord or brachial plexus injuries are indications for surgery. [18Surgery is also indicated for fractures of the humeral shaft that are associated with displaced intra-articular fracture extension. [19]

There are few, if any, absolute contraindications for surgical treatment of a midshaft humeral fracture.

The best operative treatment modality has not yet been fully determined. An association between fractures treated with antegrade intramedullary nailing and a higher number of shoulder complaints is likely, but cases involving newer nails, such as the Synthes flexible humeral nail (with a starting point lateral to cuff insertion), have not yet been monitored adequately.

Medical Therapy

Most closed fractures of the humeral shaft can be successfully treated with closed methods; union rates higher than 90% are often reported. [22021Multiple closed techniques are available, including the following [220:

  • Traction
  • Hanging arm cast
  • Coaptation splint
  • Velpeau dressing
  • Abduction humeral/shoulder spica cast
  • Functional brace

All of these techniques have been used successfully, but closed humeral shaft fractures are usually treated with a hanging arm cast or a coaptation splint for 1-3 weeks, after which period they are placed in a functional brace. [21321]

No recommendations have been made regarding the use of the hanging arm cast versus the coaptation splint, though Rockwood recommended using hanging arm casts initially for oblique or spiral fractures with shortening, when the cast can extend at least 2 cm proximal to the fracture site. [2When a hanging arm cast is used, it should be replaced, once reduction is adequate, with another treatment or should be monitored closely to look for fracture distraction and nonunion. [21In some cases, a functional arm brace can also serve as initial treatment.

The functional brace, first used by Sarmiento et al in 1977, [22consists of anterior and posterior plastic shells that are held together with Velcro straps. The fracture is kept in position through soft-tissue compression, and the brace is tightened as the swelling decreases. Over-the-shoulder extensions are available but are rarely necessary. A functional brace should not be used when massive soft-tissue injury or bone loss has occurred, when an acceptable fracture alignment cannot be maintained, or when the patient is unreliable or uncooperative. [23]

For many of the nonoperative treatments (eg, functional bracing, hanging arm casts, and coaptation splinting) to work most effectively, the patient should remain upright, either standing or sitting, and should avoid leaning on the elbow for support. This allows gravitational force to assist in fracture reduction. The patient should begin ROM exercises of the fingers, wrist, elbow, and shoulder as soon as these can be tolerated.

A Velpeau dressing or a sling-and-swathe (similar to the Velpeau dressing but less restrictive) is typically used in nondisplaced or minimally displaced fractures in children younger than 8 years, as well as in elderly patients who are unable to tolerate other treatment methods. Pads can be placed in the axilla to control fracture angulation. [21]

Acceptable alignment of humeral shaft fractures is considered to be 3 cm of shortening, 30º of varus/valgus angulation, and 20º of anterior/posterior angulation. [24Varus/valgus angulation is tolerated better proximally, and more angulation may be tolerated better in patients with obesity. Patients with large, pendulous breasts who are treated nonsurgically are at increased risk for varus angulation. No set values for acceptable malrotation exist, but compensatory shoulder motion allows for considerable tolerance of rotational deformity.

Low-velocity gunshot wounds act as closed injuries after initial treatment (debridement of skin at the entry and exit sites and a single dose of prophylactic antibiotics).

Surgical Therapy

The patient's position for surgery is determined by the method chosen for fixation. Antegrade nailing of the humerus is performed with the arm draped free and the patient in either a beach chair or a supine position. For the placement of distal locking screws, the C-arm can be rotated 180º so that the top can be used as a table to support the arm. Retrograde nailing is performed with the patient in the prone position and the arm supported on a radiolucent arm board.

Positioning for placement of plates and screws is again determined by the approach chosen. During a posterior approach, the patient is positioned prone, with the arm over an arm board. The patient is positioned supine for an anterior approach, with the extremity placed in about 60º of abduction on an arm board.

External fixation is performed with the patient supine and the arm on an arm board.

Internal fixation with plates and screws

Near-anatomic alignment can often be achieved by means of open reduction and internal fixation (ORIF) with direct fracture exposure. The rates of nonunion and hardware failure necessitating revision range from 0% to 7%. [1725The ROM of the elbow and shoulder predictably returns after plate fixation; when complete motion is not obtained, it is often the case that other associated skeletal or neurologic injuries exist. [18]

Evidence also suggests that immediate weightbearing on an upper extremity that has been treated with ORIF has little or no deleterious effect. [26The most common complications associated with plating procedures are iatrogenic nerve palsy (0-5%, with most cases being a transient problem that requires no further intervention) and infection (0-6%). [172527]

The two approaches most commonly used for fracture exposure and plate application are the posterior approach and the anterolateral approach. Either is adequate for fractures in the midthird and distal third, but fractures in the proximal third often require the anterolateral approach. [21821 The medial approach has also been described, though less commonly. [28]

The posterior approach exploits the interval between the lateral and long heads of the triceps (best found proximally). The medial head of the triceps is then incised down the midline to expose the posterior aspect of the humeral shaft. [29]

If additional proximal exposure is required, the extensile posterior approach can be used. This approach involves identifying the lower lateral brachial cutaneous nerve and radial nerve distally and then resecting the distal 3 cm of the lateral septum. This allows medial retraction of the radial nerve. The medial and lateral heads of the triceps then can be elevated off the lateral intermuscular septum and bone.

This extensile posterior approach allows exposure of the shaft proximally to the axillary nerve. [30The radial nerve crosses the posterior aspect of the humerus, where it is, on average, 20.7 ± 1.2 cm proximal to the medial epicondyle and 14.2 ± 0.6 cm proximal to the lateral condyle. [30]

In the anterolateral approach, two different internervous planes are used. Proximally, the plane is between the deltoid and the pectoralis major. Distally, the plane lies between the medial fibers of the brachialis (ie, the musculocutaneous nerve) and its lateral fibers (ie, the radial nerve). [29]

Care should be taken to avoid excessive soft-tissue stripping and devitalization of butterfly fragments. A 4.5-mm-wide dynamic compression plate (or a narrow plate in smaller individuals) is typically selected. Lag screws should be inserted when possible, and five to 10 cortices of fixation (proximal and distal to the fracture site) should be obtained. Fracture stability should then be assessed. [2132021]

The need for additional bone grafting is determined at the time of surgery. A low threshold for the addition of cancellous bone grafting should be maintained. [2]

In certain situations (eg, where humeral size is limited), however, dual small-fragment locking plate constructs may be an alternative to a single large-fragment plate. A study by Kosmopoulos and Nana suggested that in such situations, orthogonal (90º) plates may be preferable to side-by-side plates. [31]

Some surgeons prefer not to plate humeral shaft fractures, because of the difficulties of dealing with fracture exposure, the technical aspects of plating, and complex fracture patterns, as well as because of concerns about radial nerve injury. [1832]

Modified techniques for minimally invasive plating have been reported. [3334 Although minimally invasive plate osteosynthesis (MIPO) is a difficult procedure, satisfactory outcomes have been achieved by skilled surgeons with an understanding of neurovascular anatomy. [34353637]

Internal fixation with intramedullary implants

Intramedullary fixation has gained popularity in this setting. Initial reports found there to be a higher nonunion rate with such fixation than with conservative treatment or with ORIF with plates and screws. However, several subsequent reports demonstrated that with newer implants and improved techniques, locked intramedullary nailing could achieve a success rate as high as that of the other methods. [32738394041424344454647In these studies, the incidence of nonunion was approximately 6%, the incidence of infection was 2%, and the incidence of radial nerve palsies was 3%.

Intramedullary nailing can be used to stabilize fractures that are 2 cm below the surgical neck to 3 cm proximal to the olecranon fossa. Results comparing ORIF with locked intramedullary nailing have failed to demonstrate any difference in blood loss or operating room time. [1827]

Intramedullary nails have certain potential advantages over plates and screws. The intramedullary nail is closer to the normal mechanical axis and can act as a load-sharing device if there is cortical contact. The nails are subjected to lower bending forces and thus are less likely to fail through fatigue. Intramedullary nails can be placed without direct fracture exposure and with much less soft-tissue dissection. Additionally, cortical osteopenia caused by stress shielding (as is seen with plates and screws) is less likely.

Standard locked intramedullary humeral nails can also be inserted via either an antegrade or a retrograde approach. The antegrade approach typically involves a starting point at the proximal humerus; this point can be through the rotator cuff, where the tissue is less vascular, or just lateral to the articular surface, where the blood flow is higher.

The procedure can be started with a small incision made with the aid of fluoroscopy or with a larger incision in which the cuff is identified and purposefully incised. No evidence has indicated that either method is superior. [484950The nail can be placed with or without reaming (no evidence suggests that either method is superior with regard to healing time and complication rate), then locked proximally and distally. [18]

Care must be exercised in the placement of the proximal locking screws because the axillary nerve lies 5-6 cm distal to the edge of the acromion. [32The distal locking screw can often be placed by means of a lateromedial or an anteroposterior approach. The lateromedial technique puts the radial nerve at risk, and the anteroposterior method places the musculocutaneous nerve at risk. An alternative and possibly safer method involves placing the screw posteroanteriorly. [13 It has been suggested that a distal locking screw may not be absolutely necessary. [51]

Retrograde insertion of intramedullary humeral nails requires a distal triceps-splitting approach and the use of a hole, 1 cm wide and 2 cm long, that is placed 2.5 cm proximal to the olecranon fossa. [18The starting hole must be beveled along the path of the nail insertion. [13The nail can be locked proximally, either lateromedially (placing the axillary nerve at risk) or anteroposteriorly (placing the biceps tendon at risk).

If any resistance is met during attempted passage of the nail, either antegrade or retrograde, consideration should be given to making a small incision to ensure that the radial nerve is not entrapped in the fracture site.

The use of flexible nails (often Ender nails with a 3.5-mm diameter) has become limited to isolated cases of transverse or short oblique fractures with a canal larger than 7 mm. These nails can be inserted either retrograde (the more common approach, accomplished through triceps splitting with an entry portal just above the olecranon fossa) or antegrade.

These nails can be locked at the end with wire or 3.5-mm cortical screws to prevent migration, but no method of statically locking the nails exists. Therefore, bending and angulation can still occur in spiral or comminuted fractures. Furthermore, a canal of less than 7 mm only allows insertion of one nail. [18]

Studies of the outcome of humeral fractures treated with flexible intramedullary nailing (Ender nails) reveal that antegrade insertion is associated with shoulder dysfunction (pain and decreased ROM) in 5-10% of patients and that hardware removal is not entirely effective in relieving symptoms. [525354A starting point outside the rotator cuff may help decrease these numbers. Reports on the use of Rush rod fixation have demonstrated unacceptably high rates of nonunion, delayed union, and shoulder pain. [55]

With retrograde nailing, union rates range from 91% to 98%, and rates of infection (which is mostly associated with open fractures) range from 0% to 2%. With the use of multiple nails, hardware failure is reported to be rare, and the rate of iatrogenic radial nerve injury, which is usually temporary, is placed at 3%. [18]

Locked intramedullary nailing in an antegrade fashion has resulted in loss of shoulder motion in 6-37% of cases. [4850It has also been reported that retrograde nailing is not associated with shoulder pain and that the return of elbow motion is not a problem unless other associated injuries are located in the fractured extremity. [18A concern also exists that once the retrograde nail has been placed, the starting hole just distal to this may act as a stress riser. [32]

Biomechanical studies have shown that for midshaft fractures, retrograde and antegrade nailing showed similar initial stability, bending, and torsional stiffness. In proximal fractures (10 cm distal to the greater tuberosity tip), the antegrade nails have demonstrated significantly more initial stability and higher bending and torsional stiffness, as has been true for distal fractures with retrograde nailing. [56]

Nonunions in humeral fractures after treatment with plate and screws typically respond well to replating with the addition of bone graft. This is not the case when nonunions follow treatment with humeral nails. If a humeral nonunion treated with an intramedullary nail is treated with exchange nailing, the success rate can be as low as 40-60%. [5057However, if the nail is removed and ORIF with bone grafting is performed, the union rate is again very high. However, this is a more technically difficult scenario. [32]

External fixation

Traditionally, external fixation of humeral shaft fractures has been limited to open fractures. The open wound should be treated in an appropriate manner and, for Gustilo grade I or II wounds, followed by ORIF or unreamed intramedullary nailing. For grade III wounds, external fixation is the treatment of choice. Debridement is performed every 48 hours until the wound is clean. Then, at the final debridement, bone grafting may be used if needed. [21Treatment of humeral shaft fractures with an external fixator carries a high complication rate. [58]

Complications

Radial nerve injury occurs in as many as 18% of humeral shaft fractures. [59Although the oblique distal third humeral fracture (Holstein-Lewis) is better known for an association with radial nerve palsy than other humeral shaft fractures are, such palsy most commonly occurs with middle third humeral fractures. [60Most of these nerve injuries are neurapraxic or axonotmetic types, 90% of which resolve to at least grade IV strength in 3-4 months. [1760]

Indications for early nerve exploration include a palsy associated with an open wound or penetrating injury. The question of whether it is best to explore a radial nerve when function decreases after closed manipulation has been controversial. Some authors have recommended waiting to perform exploration if no return of function is observed after 3-4 months, [61stating that the results of secondary repair of radial nerve injuries are as good as those of primary repair and that the situation has been made easier because the fracture has had time to heal. [2]

Brachial artery injuries that are associated with humeral shaft fractures are uncommon. At risk fractures are those in the proximal and distal thirds of the arm. [2Surgical stabilization of fractures associated with arterial injury is mandatory at the time of vascular repair.

A period of 4 months has been noted to be adequate to allow humeral shaft fractures to heal. The nonunion rate reportedly ranges from 1% to 15%. A higher nonunion rate for humeral shaft fractures has been associated with transverse fractures, as well as with such factors as fracture distraction, soft-tissue interposition, inadequate shoulder immobilization, and decreased shoulder motion. [626364]

Medical factors that decrease the union rate include diabetes mellitus, corticosteroid use, older age, poor nutritional status, obesity, fractures underlying a burn, and previous radiation. [6566Functional bracing has little role in nonunion. Electrical stimulation may be beneficial but should not be used when infection, a gap of more than 1 cm, or a synovial pseudarthrosis is present.

ORIF with compression plates and screws, with or without the aid of bone grafting, is considered to be the treatment of choice for most established nonunions. Some reports describe nonunions being treated with retrograde intramedullary nails and antegrade nails, with a union rate similar to that associated with ORIF.


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