Six-year-old Rosie was running in from the back yard when she tripped over the skateboard that her mum had told her to tidy up. She landed directly on her left arm. She was brought to the ED and it was noted she was unable to extend her left wrist and she had pins and needles over the back of her hand.
Humeral shaft fractures are uncommon, accounting for less than 10% of paediatric fractures. Children have a remarkable ability to remodel and heal with little or no deformity despite significant displacement and angulation; therefore, most of these fractures can be managed with simple immobilisation.
Anatomy
The thick periosteal sleeve of the humerus limits the displacement of humeral fractures and promotes excellent healing. The main anatomical feature essential to remember is the radial nerve, which curves around the back of the mid-humerus and is at risk of injury. That said, injuries of the radial nerve secondary to humeral fractures are rarely associated with long-term deficits, with the majority being temporary neuropraxia.
Mechanism of injury
Neonates – hyperextension or rotation as they pass through the birth canal. The typical fracture is a transverse midshaft fracture.
Older children – Fall on an outstretched hand (FOOSH), a direct blow to the upper arm or high-energy trauma such as a motor vehicle collision.
Pathological fracture – suggested when a midshaft humeral fracture occurs after only minimal trauma. The humerus is a common site for bone cysts and other benign lesions. These occur most commonly in children 3-12 years of age.
Non-accidental injury – Is the mechanism inconsistent with the injury, or is there a fracture in a healthy child younger than three years? This should raise concern for child abuse. These fractures can be transverse fractures from a direct blow or an oblique or spiral fracture caused by traction with humeral twisting.
Evaluation
These injuries often present with mid-arm pain and swelling. If a humeral fracture is present with no visible deformity, it is typically minimally displaced.
Determine if there is any distal neurovascular compromise (check out the elbow examination post for tips on neurovascular assessment in upper limb injuries). Vascular injuries are infrequent, but midshaft fractures are associated with radial nerve injuries in 5% of fractures. This will be evident with paraesthesia/numbness in the dorsum of the hand between the 1st and 2nd metacarpal and motor deficit with reduced thumb and wrist extension and forearm supination.
Radiology
Typical anterior-posterior (AP) and lateral views are sufficient. A prominent vascular groove in the distal humerus is commonly seen on plain film and should not be confused with a fracture line.
Describing humeral fractures
There are four key descriptors of humeral fractures:
- Anatomical location: proximal, middle or distal third
- Fracture pattern: spiral, short oblique, transverse or comminuted
- Degree of displacement and angulation
- Presence of soft tissue damage: is the fracture open or closed?
Analgesia and immobilisation
Give early analgesia. These are sore, and children often require opiate analgesia such as intranasal fentanyl or diamorphine, which are safe to give if there is no facial trauma or signs of head injury present.
Immobilization in a sling and swathe or shoulder immobilizer enhances patient comfort and reduces the chance of further fracture displacement. Be sure to check for and document any neurovascular deficit pre and post immobilization.
Infants – sling and a swathe for 4 weeks is sufficient regardless of the degree of displacement.
Older children – In incomplete fractures then a sling and swathe, a collar and cuff sling or a shoulder immobiliser can be used.
Complete and moderately displaced fractures are better managed in a hanging U-slab. This uses gravity to decrease the deformity by relaxing the muscles and also improves the child’s comfort. Provided there is no radial nerve injury, the fracture can be reduced under procedural sedation to improve clinical alignment. After reduction, the child is placed in a U-slab or coaptation splint for two weeks. In the fracture clinic, they will then be reassessed and braced in a functional clamshell brace until approximately four weeks.
Refer for orthopaedic assessment in ED if there are any of the following features present:
- Compound fracture with neurovascular compromise
- Open fracture
- 100% displacement
- Fracture with clinical deformity
- Angulation more than 20° in children and 10° in adolescents
- Compartment syndrome (rare in midshaft humeral fractures)
Operative management involves open reduction and internal fixation. It is indicated in many of the above but also the multiply injured patient to aid in early ambulation, including concomitant forearm fractures resulting in a “floating elbow”.
Outcomes
- Malunion is common, but there’s usually little functional loss. These remodel well.
- Initial fracture shortening may be compensated for by later overgrowth
- Nonunion is uncommon
- Radial nerve palsy is less common, and when occurs, is usually a temporary neuropraxia
Rosie was brought to theatre for an open reduction of her left midshaft humerus fracture. The radial nerve was trapped in the fracture line but not severed. After a few weeks of physio, Rosie has regained full movement of her wrist and hand, and she loves having a scar on her arm. Skateboards have been banned in the house…
References
- JC. Cheng, JY. Shen. Limb fracture pattern in different pediatric age groups: a study of 3,350 children. J Orthop Trauma. 1993;7(1):15
- S. Carson, DP. Woolridge, J. Colletti, K. Kilgore, Pediatric upper extremity injuries. Pediatr Clin North Am. 2006 Feb;53(1):41-67, v.
- Figure 3 – Case courtesy of Dr Hani Salam, <ahref=”https://radiopaedia.org/”>Radiopaedia.org</a>. From the case <ahref=”https://radiopaedia.org/cases/13537″>rID: 13537</a>
- https://emedicine.medscape.com/article/1231103-overview
- https://www.rch.org.au/clinicalguide/guideline_index/fractures/Humeral_shaft_fractures_Emergency_Department/
