“Slow down!” Joel’s mom shouts at him as he whizzes past on his scooter. Joel turns to answer and doesn’t see the curb, which he hits. He goes flying and puts out his hand to stop himself. Mom is already running to find him holding his arm.
Proximal humeral fractures are uncommon, accounting for less than 5% of all paediatric fractures. The anatomic characteristics of the proximal humerus can explain the various fracture presentations, complications and outcomes.
Anatomy
Ossification centres
The proximal humeral physis has three ossification centres. Head, lesser tuberosity and greater tuberosity. The capital centres appear at 3 months, whereas the two others appear at 1 year of age and fuse between 3 and 5 years to produce tuberosity ossification. By the time the child is 6, the capital and tuberosity centres fuse into a single proximal epiphyseal centre. At this point, it acquires a characteristic ‘tent’ or inverted V shape. This also results in a double contour that can complicate the interpretation of the images. The proximal physis accounts for approximately 80% of the longitudinal growth of the entire bone.
Periosteum
This thick sleeve of periosteum is present along the shaft and limits fracture displacement, and promotes healing.
Nerves
The axillary nerve, which supplies the sensory innervation to the regimental badge area, is at potential risk in displaced proximal humeral fractures. However, axillary nerve damage is rare, the majority being only temporary neuropraxia.
Epidemiology
Proximal humeral fractures show an early modest peak at 10-14 years of age, accounting for up to 3.5% of all fractures, followed by a return to low levels in young adults and then a second increase in later adulthood.
These fractures account for a third of all humeral fractures in neonates and are the second most common birth injury after clavicular fractures. However, they are still rare, occurring in only 0.03 per 1000 births.
The pattern of injury varies with age. Metaphyseal proximal humeral fractures are proportionately higher in pre-pubertal children compared to a higher proportion of epiphyseal separation in adolescents.
As with any fracture, be aware of the potential of a non-accidental cause. These fractures can be associated with physical abuse.
Mechanism of Injury
Indirect
Proximal humeral fractures in non-newborns commonly result from a fall backwards onto an outstretched hand with elbow extended and wrist dorsiflexed or a direct blow to the lateral aspect of the shoulder. Pathological fractures can occur as the humerus is a common location of bone cysts and other benign lesions. This might occur with minimal trauma.
Birth injuries
The upper arm can be hyperextended or rotated during delivery, occurring more commonly in infants of diabetic mothers and with shoulder dystocia.
Clinical Evaluation
Newborns
Typically, a newborn with a proximal humeral fracture will hold their arm in extension. Consider these fractures if a history of birth trauma is given. If noted, then infection, clavicle fracture, shoulder dislocation and brachial plexus injuries need to be ruled out. These little ones may be irritable, particularly when the upper limb is moved.
Children and adolescents
As with other upper arm fractures, the typical presentation is pain, dysfunction, bruising and swelling with a painful range of movement. Displaced fractures result in significant anterior swelling and altered shoulder appearance relative to the contralateral side.
A detailed distal neurovascular examination is needed, including evaluation of the radial, ulnar, median, axillary and musculoskeletal nerves. Be particularly vigilant for any axillary nerve deficit with decreased sensation over the regimental badge area and loss of the deltoid muscle function (shoulder ABDuction).
Radiology
Proximal humeral fractures are identified on routine AP and axillary views of the humerus. If there is a clinical concern of dislocation, then dedicated shoulder views should also be taken. If there is tenderness over the physis and no obvious fracture, a suspicion of a Salter-Harris (SH) I fracture can be made. Imaging the contralateral humerus may be helpful to determine if there is any widening of the physis.
Patterns of fracture
There are two variations of proximal humeral fractures: metaphyseal and epiphyseal separation.
- Metaphyseal fractures (70%) usually occur at the surgical neck, although they can also occur at the metaphyseal-diaphyseal junction, typically a transverse or short oblique fracture. These fractures typically occur in 5-12 year olds.
- Epiphyseal fractures (30%) occur in the under 5s and over 12s. The type of epiphyseal fracture depends on skeletal maturity.
SH I fractures are less common and can be seen at all ages before growth-plate closure, most commonly in <5 year olds.
SH II fractures are the most common type, chiefly in adolescents over the age of 12.
SH III and IV fractures are exceedingly rare.
Pathological fractures
40% of pathological fractures involve the proximal humerus. The leading cause is a unicameral bone cyst, as this lesion develops in the proximal humerus in 51% of cases. Other causes are aneurysmal bone cysts, non-ossifying fibromas, fibrous dysplasia and bone malignancies.
Displacement
If a proximal humeral fracture displaces, it usually does so in a varus direction, with the humeral head moving medially and posterior to the shaft. This occurs due to pectoralis major traction pulling the distal segment medially, while the rotator cuff and deltoid pull the proximal component superiorly in a tendency towards flexion and external rotation. Displacement is often absent or minimal in 40% of metaphyseal fractures but is more common in epiphyseal injuries, occurring in up to 85%.
Classification
The Neer-Horowitz classification is the most frequently used classification system for this type of fracture. It divides the proximal humerus into 4 parts, classifying fracture by the degree of displacement as well as the fracture line, consisting of:
- Humeral head
- Greater tuberosity
- Lesser tuberosity
- Humeral shaft
One-part fractures involve 1 – 4 undisplaced parts (<1cm AND <45 degrees)
Two-part fractures account for 20% of proximal humeral fractures, involving 2 – 4 parts, 1 of which is displaced (i.e. >1cm OR >45 degrees)
- Surgical neck – most common
- Greater tuberosity – often seen with anterior shoulder dislocation. A lower threshold for displacement (>5 mm) has been proposed.
- Anatomical neck
- Lesser tuberosity
Three-part fractures account for 5% of proximal humeral fractures and involve 3 – 4 parts, two of which are displaced (i.e. > 1cm OR > 45 degrees)
- Greater tuberosity and shaft displaced with respect to lesser tuberosity and articular surface, which remain together.
- Lesser tuberosity and shaft are displaced with respect to the greater tuberosity and articular surface, which remain together.
Four-part fractures are uncommon, occurring in less than 1% of proximal humeral fractures. They involve more than four parts, three of which are displaced (i.e. >1 cm OR > 45 degrees with respect to the 4th). Four-part fractures require operative reduction.
Management
Initial treatment
Displaced fractures can be very painful, so ensure pain is addressed with adequate analgesia.
The aim of immobilisation is to keep the elbow by the side, flexed to 90 degrees, with the forearm against the torso. A simple sling is sufficient plus / minus a swathe for younger ages. Straps and adhesive tape can be used as described by Durrajer. Other options include a shoulder immobiliser or a U-shaped coaptation splint.
Neurovascular status must be checked before and after immobilisation.
Orthopaedic consultation should be obtained if there is:
- associated shoulder dislocation
- intra-articular (SH IV) fracture
- completely displaced fracture in a child over 12 years.
- associated neurovascular compromise
- open fracture (rare)
- evidence of compartment syndrome
Definitive Treatment
Newborns usually have SH I fractures, which have an excellent prognosis. A sling and a swathe is sufficient for up to 4 weeks. The primary role of follow-up is to ensure there is no brachial plexus injury.
Children and adolescents with minimally displaced fractures are usually managed with a sling or shoulder immobiliser. Gentle pendulum exercise is started between weeks 2 and 4 post-injury, and active range of movement is started at 4 and 6 weeks. We would expect normal function in 2 months.
Significantly displaced fractures in children 12 and under should be treated with a U-slab, sling and swathe.
Acceptable angulation
- < 5 years – any degree is allowed as proximal humeral fractures in young children have excellent remodelling potential.
- 5 to 12 years – 40 to 70 degrees of angulation is acceptable
- >12 years – up to 40 degrees of angulation or 2/3 displacement.
Operative
Fractures in which immobilisation would result in unacceptable alignment are managed with closed reduction +/- fixation. Open reduction and internal fixation (ORIF) is indicated if an acceptable reduction is not possible due to soft tissue interposition. Most commonly, this is caused by the long head of the biceps tendon, but it can also be caused by the joint capsule, infolded periosteum and deltoid muscle. ORIF is also indicated in open fractures, compound fractures and intra-articular displacement of the fracture.
Complications
Complications are rare in children, but when they do occur, they are more common in older children, with shortening of the humerus due to physeal damage. This usually has no functional effect. Radiographic malunion can occur but rarely has any functional effect.
Non-accidental injury
Finally, as with any fracture, it is imperative that a mechanism inconsistent with an injury or fracture in an otherwise healthy child should prompt escalation and involve the child protection team.
Joel’s x-ray shows a proximal humeral fracture through the surgical neck, with 20 degrees of angulation.
He’s placed in a shoulder immobiliser and followed up in a fracture clinic, where he’s advised to start gentle pendulum exercises after a couple of weeks.
Two months later, he’s back on his scooter, helmet on, flying down the pavement without a care in the world.
References
LA. Landin. Epidemiology of the children’s fractures. J Pediatric Orthop B. 1997;6(2):79
E.J. Ortiz, M.H. Isler, J.E. Navia, R. Canosa, Pathologic fractures in children. Clin Orthop Relat Res, 432 (2005), pp. 116-126
MW Shrader et al., Proximal humerus and humeral shaft fractures in children. Hand Clin 2007;23(4);431
