Proximal humerus fractures makeup approximately 2% of all pediatric fractures.1 These fractures occur most commonly in adolescents 11 to 15 years of age, and they occur more commonly in males, with a male to female ratio of 3 to 1.2 Fractures of the proximal humerus can be purely metaphyseal or can involve the physis and/or epiphysis. Metaphyseal fractures are typically seen in children between 5 and 11 years of age, often as torus fractures. Physeal fractures makeup the minority of proximal humerus fractures with an incidence of only 2.2 to 4.5 per 1000 per year,3 accounting for 4% to 7% of all physeal fractures.2 Eighty-five percent of pediatric proximal humerus fractures are nondisplaced or minimally displaced.4 The remaining 15% are severely displaced, more commonly in children below 3 or above 12 years of age.5
The proximal humerus epiphyseal ossification center appears on x-ray at 6 months of age. It starts as 3 ossification centers: the proximal humerus, the greater tuberosity, and the lesser tuberosity. The ossification centers for the greater tuberosity and lesser tuberosity appear at 3 and 5 years, respectively,2 and all 3 ossification centers coalesce into one around 6 years of age.6 The proximal humerus physis closes between 14 and 17 years of age in females, and between 16 and 18 in males.7,8
The humerus has the highest proximal physis to distal physis growth ratio differential among all long bones, with the proximal humerus being responsible for 80% of overall humeral linear growth.2 This allows for significant remodeling potential following fracture of the proximal humerus. In addition, the glenohumeral joint is the most mobile joint in the body. Glenohumeral mobility, along with elbow motion, compensate well for malunions of the proximal humerus. Furthermore, fractures of the proximal humerus that involve the physis occur through the zone of degenerating cartilage, which is distal to the proliferating cells. The fracture line usually exits the posteromedial corner of the diaphysis, sparing those cells responsible for longitudinal growth.2
As a result of multiple deforming muscle forces, the typical deformity of a proximal humerus fracture is varus and apex anterior angulation. The supraspinatus muscle inserts onto the greater tuberosity and abducts the proximal fragment. The teres minor and infraspinatus also insert onto the greater tuberosity, but they externally rotate and flex the proximal fragment. The subscapularis inserts onto the lesser tuberosity and internally rotates the epiphysis, thus countering the external rotation force of the teres minor and infraspinatus. The pectoralis major inserts on the proximal medial humeral shaft and adducts and anteriorly translates the distal fragment. The deltoid inserts on the deltoid tuberosity of the humerus, abducts the distal fragment, and causes shortening at the fracture site. Lastly, the biceps and triceps insert distally on the forearm and displace the distal fragment proximally and medially.2
The majority of pediatric proximal humerus fractures are a result of a direct fall onto the shoulder or a direct blow to the shoulder. Another less common mechanism of injury is a fall onto the outstretched hand with the arm abducted and externally rotated. In infants, proximal humerus fractures are usually the result of birth-related trauma and are most often a Salter-Harris (SH) I fracture of the proximal humeral physis. Lastly, pediatric proximal humerus fractures can be pathologic, most commonly associated with aneurysmal bone cysts and unicameral bone cysts.6
The commonly used classification of pediatric proximal humerus fractures was reported by Neer and Horowitz (N-H) in 19652 and was based on the amount of displacement of the humeral shaft relative to the width of the humeral shaft. In addition, proximal humeral physeal fractures can be classified according to the SH classification. Little Leaguer’s Shoulder is a special type of fracture of the proximal humerus seen in adolescents. It is a SH I fracture of the proximal humerus that is caused by repetitive throwing motions. Treatment for Little Leaguer’s Shoulder consists of rest and physical therapy followed by gradual return to sport.
PRINCIPLES OF MANAGEMENT
Most proximal humerus fractures in skeletally immature individuals are treated nonoperatively with excellent functional results (Figs. 1A, B). Extensive remodeling of the proximal humerus and the wide arc of motion of the glenohumeral joint accommodate a large degree of fracture displacement and angulation. Older patients and those patients with significantly displaced fractures may benefit from surgery because of their lower capacity for bone remodeling during their limited remaining growth.
Absolute indications for surgical treatment of proximal humerus fractures in skeletally immature patients include open fractures, tenting of the skin (impeding open fracture), associated neurovascular injury, and intra-articular displacement.9,10 Relative indications include severely displaced (N-H grade III or IV) fractures, severely angulated fractures, multiple trauma, associated head trauma, and fractures in patients with a neuromuscular disorder or nerve palsy. Patients with neuromuscular disorders, such as cerebral palsy or muscular dystrophy, or nerve palsies have an absence of normal muscular forces, resulting in unpredictable remodeling.6 Debate continues regarding the treatment of severely displaced and angulated fractures.
The decision to treat a proximal humerus fracture in a skeletally immature patient operatively versus nonoperatively is dependent on the following 3 factors: displacement, bone age, and capacity to remodel.11 In the absence of the previously mentioned absolute and relative indications, N-H grade I and II fractures are treated without surgery. Nonsurgical treatment consists of immobilization for 3 to 4 weeks for comfort. Current immobilization options include sling, sling and swathe, hanging cast, or valpeau bandage.
Surgical options for proximal humerus fractures in skeletally immature patients include closed reduction with percutaneous fixation (pinning), open reduction with percutaneous fixation, and open reduction with internal fixation. Closed reduction can be obtained in most patients. The reduction maneuver typically consists of longitudinal traction, shoulder abduction to 90 degrees, and shoulder external rotation.1 If a reduction cannot be obtained closed, an open reduction via a limited deltopectoral approach should be performed. In most cases of a failed closed reduction, there is soft tissue interposed between the fracture fragments, most commonly the biceps tendon. An entrapped biceps tendon was found in 9.4% of patients treated operatively in a systematic review by Pahlavan et al.11 In addition, torn periosteum may block reduction. The posteromedial periosteum is stronger than the anterolateral periosteum. In a situation in which the anterolateral periosteum ruptures while the posteromedial periosteum remains intact, the anterolateral periosteum can become incarcerated within the fracture, causing irreducibility by closed methods.5 Other possible obstacles to closed reduction include the deltoid muscle, joint capsule, and comminuted bone.12
If closed or open reduction is performed, fixation should be performed to prevent redisplacement. Smooth wires, percutaneous threaded wires, cannulated screws, and retrograde elastic stable intramedullary nailing (ESIN) are acceptable options for fixation. Most commonly, smooth wires are used (Figs. 2A–C). After insertion, wires can be left exposed or buried under the skin surface. Exposed wires carry the risk of infection, whereas buried wires may require a second operation for removal. Plate and screw constructs can be used for fixation as well, but should be reserved for older patients after the start of physeal closure.13
The risks of each surgical technique should be understood. With closed reduction and percutaneous pinning, the axillary nerve and the posterior humeral circumflex artery are at risk during pin insertion.14 Using blunt dissection before placing the fixation wire directly on the humeral cortex can minimize this risk. In addition, a more distal starting point can decrease the risk of axillary nerve injury, and external rotation of the arm can decrease the risk of posterior humeral circumflex artery injury. Other complications include pin-site infection, possibly requiring premature pin removal and perforation of the humeral head.1 The risks of ESIN include physeal damage if the physis is crossed during nail insertion. However, in Fernandez et al’s1 series of 35 patients, no patient had evidence of premature closure of the physis or arm length discrepancies when ESIN was used.
When performing retrograde percutaneous pinning, the following techniques are helpful. Placing the patient in the beach chair positioning makes manipulation of the arm by the surgeon more efficient and enables better C-arm fluoroscopy access. Positioning the C-arm at the head of the table allows good axillary lateral views. After patient positioning, closed reduction is performed and confirmed radiographically. If successful, retrograde pinning could be performed at this point. However, the position to hold the reduction (shoulder abduction and external rotation) often makes it difficult to insert the fixation wires with the proper trajectory. A solution to this challenge is to adduct the arm when the fixation wires are first introduced into the diaphysis. The wires are then advanced retrograde to the fracture site. The fracture is then rereduced, and the wires are advanced across the fracture site into the proximal epiphysis. Leaving the pins exposed versus buried is at the discretion of the surgeon. Leaving the pins exposed allows for pin removal in clinic. In cases where it is difficult to control the proximal fragment during reduction, the surgeon can insert a temporary wire into the greater tuberosity and epiphysis and manipulate the proximal fragment. Once the definitive wires are placed, this manipulation wire is removed.
Most proximal humerus fractures are treated nonoperatively with favorable outcomes, but the treatment of severely displaced fractures and/or severely angulated fractures continues to be a topic of debate. Several studies have recommended surgical reduction and fixation in N-H III and IV fractures in older patients.3,10,15 Similar recommendations have been made for displaced and angulated metaphyseal fractures.1,16
Chronologic age can be used to infer a patient’s remodeling potential, and hence criteria for acceptable alignment. In children 10 years of age and younger, up to 60 degrees of angulation can be remodeled. This value decreases to 20 to 30 degrees in patients over 10 years of age.1,5 Nonetheless, in a review of published studies, Popkin et al6 found that proposed criteria for acceptable angulation and displacement of N-H grade III and IV fractures varied widely (Table 1).
There is a paucity of high level of evidence studies comparing operative and nonoperative treatment of proximal humerus fractures. Pahlavan et al11 performed a systematic review of the literature. Fourteen studies met the inclusion criteria, of which the highest level of evidence was level IV. The authors concluded that nonsurgical treatment of proximal humerus fractures in skeletally immature patients resulted in excellent outcomes, malunions were rare and well tolerated, and most patients returned to their preinjury function.11 Patients with N-H IV fractures had worse outcomes in regards to pain, shortening, restriction of motion, and residual angulation, as did patients older than 13 years with widely displaced fractures. On the basis of this systematic review, Pahlavan et al11 recommended that all patients below 10 years old should be treated nonoperatively, patients 10 to 13 years old should be treated on a case-by-case basis based on sex, true bone age, and biological capacity to remodel, and patients older than 13 years should be treated operatively if displacement warrants it. In addition, high-demand adolescent athletes may benefit from surgical treatment, given their limited remodeling potential and lower functional tolerance for malalignment.20
More recently, Chaus et al21 performed a matched cohort study of patients with N-H type III or IV physeal fractures treated operatively versus nonoperatively. They found a significant association between increasing age and the odds of a less desirable clinical outcome with nonoperative treatment, specifically after 12 years of age. There were no differences in complication rate, return to activity rate, or cosmetic satisfaction between the 2 groups. This is consistent with other studies that have shown worse outcomes in older adolescents.3,10,15,18,22 On the basis of their findings, these authors advocate for more aggressive surgical treatment in older patients.
Shore et al23 performed a cost analysis of percutaneous pinning versus ESIN in 84 displaced proximal humerus fractures (35 treated with ESIN, 32 with percutaneous pinning with pins left exposed, and 17 with percutaneous pinning with buried pins) and found that percutaneous pinning with exposed pins was more cost-effective, resulting in a cost savings of $4500 per person. Hutchinson et al19 compared the outcomes of percutaneous pinning versus ESIN. Fifty skeletally immature patients with an average age of 13.7 years underwent closed or open reduction with percutaneous pinning (27 patients) or ESIN (23 patients). All patients were at least 12 years old and had N-H grade IV fractures or angulation >40 degrees. All fractures healed clinically and radiographically, and there was no discernible functional loss of range of motion, pain, or weakness. The authors concluded that both methods are safe and effective, but neither was superior to the other.
High quality evidence-based studies addressing treatment of proximal humerus fractures in skeletally immature patients are lacking in the literature. Such studies are needed to clarify surgical indications related to displacement, angulation, and age and optimal management and fixation techniques. On the basis of a review of published studies, the strongest statement that can be made is that there is an increasing trend toward treating severely displaced and severely angulated fractures surgically, especially in older adolescents who have little remaining remodeling potential. A randomized controlled study that compares nonoperative versus operative management would be ideal. As severely displaced proximal humerus fractures are uncommon, a multicenter study would better enable a sufficient sample size.
The authors thank Robert Bielski, MD, and Prasad Gourineni, MD, for clinical cases.
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