Humeral Shaft Fractures -

Epidemiology

Humeral shaft fractures make up 3% of all fractures.

Treatment

Nonoperative

functional bracing
- function of the upper limb is not affected by up to
  - 20° of anterior angulation
  - 30° of varus angulation
  - 3cm of shortening
- muscle bulk in the upper limb disguises the deformity
- Varus/valgus deformity is best tolerated closer to the shoulder
- Considerable malrotation is well tolerated

Operative

Indications

Type III open fractures
Polytrauma with substantial head & or chest injury
Ipsilateral fracture of both bones of forearm (floating elbow)
Bilateral humeral fractures
Extensive local injuries including:
- Shoulder or elbow dislocation
- Brachial plexus injury
Impending pathological fracture
Marked obesity which will make closed management difficult, as will large breasted women

radial nerve injury sustained at the same time as a humeral fracture is not an indication for exploration or for internal fixation.

Plate fixation

Pros
- lower rate of complications than IMN & a higher union rate.
- nonunion rate
  - 0 to 7%.
- infection rate
  - 0-6%.
- iatrogenic nerve palsy
  - 0-5%
    - most are transient & do not require further intervention
Technique
- Approach
  - extensile anterolateral approach
  - for distal humeral fractures it can be via a posterior triceps splitting approach
- Fixation
  - Eight cortices of fixation
  - broad 4.5mm compression plate with staggered holes
- Position of Plate
  - upper humerus
    - anterolaterally
  - distal humerus
    - posterior
- radial nerve
  - must be protected throughout
- open fractures
  - preferable to plate the wound through a clean separate incision unless the wound is anterolateral
- impending pathological fracture plate fixation
  - use of methylmethacrylate for supplemental fixation
- Segmental fractures
  - IMN is not suitable for fractures of the proximal & distal quarters of the humerus, & segmental fractures of this type should be fixed with plates using separate plates through separate incisions

Intramedullary nailing

Pros
- Biomechanical & physiological advantages
  - nail is closer to the mechanical axis of the humerus,
    - hence has less of a bending load
  - less soft tissue stripping is required
Cons
- higher complication rate with IMN than plating
  - lower union rate
  - ↑ shoulder pain & stiffness
    - shoulder dysfunction 6-37%
- Distal retrograde nailing
  - less shoulder dysfunction but more elbow dysfunction
  - periprosthetic fracture
- Damage to axillary nerve
  - axillary nerve can be at risk during percutaneous locking proximally
  - axillary nerve is an average of 45.6mm below the tip of the GT
Indication
- fractures in the middle two fourths of the humerus
Technique
- superior entry point
  - percutaneous vs formal open approach with exposure & longitudinal splitting of the rotator cuff.
    - There has been no difference demonstrated between these approaches.
    - latter is theoretically better, as the cuff is violated in an area of improved blood supply & is formally repaired
- If resistance is met when passing the nail, the fracture should be opened to rule out incarceration of the radial nerve
Results
- rates of radial nerve injury, infection, delayed union (up to 20%) & failure of fixation appear to be similar for plating & nailing

Functional bracing

Action
- gravity results in adequate alignment of the bone
- physiologically induced motion at the fracture side induces osteogenesis & secondary bony union
- Functional braces stiffen the upper arm through soft tissue compression
Details
- often some varus malunion which is cosmetically & functionally acceptable
- brace should extend from 1cm distal to the axilla to one cm above the humeral condyles
- Active abduction & elevation of the shoulder must be avoided because they may produce angular deformity
- Leaning on the elbow should be avoided as it may cause varus angulation
Requirements
- patient needs to be able to sit up or stand
- highest failure rates
  - obese patients
  - transverse fractures
    - particularly ones that are not displaced
Contraindications
- axial distraction between the fragments
Compound Fractures
- Functional bracing can be used with Grade I & II open injuries
Results
- nonunion rate of 1.5% for closed fractures
- 5.8% for open fractures
- Patients have nearly a full range of shoulder & elbow motion

Complications

Radial nerve injuries

Incidence
- 18% of Holstein-Lewis fractures
- Most are neurapraxias & 90% resolve within 9 months.
There are three main strategies possible in radial nerve injuries associated with humeral fractures
- Immediate exploration
  - Points in favor
    - Status of nerve can be established, which has prognostic information
    - Stabilization of the fracture by internal fixation protects the radial nerve from further damage
    - Early operation is easier & safer
  - Points against
    - vast majority of radial nerve injuries will recover spontaneously
    - It is uncommon to find a surgically treatable radial nerve lesion upon exploration
- Nerve exploration at 6-8 weeks if no return
  - patients who were going to get recovery did so by 8 weeks
  - this length of time would allow proper delineation of a neuroma but would avoid excessive retraction
  - However, recovery is often seen after this time
- Nerve exploration if no return after a longer waiting period
  - time expected for recovery can be calculated by measuring the distance from the fracture to 2cm above the lateral epi-condyle, where brachioradialis gets its innervation, & allowing 1mm/day plus 30 days.
  - Thus it can take 4-5 months for evidence of function to be seen in the brachioradialis or wrist extensors
  - prospects for recovery are better when repair is performed within 6 months of injury
preferred option may therefore be to wait for 6 months after injury before performing nerve exploration.
The results of nerve repair can be gratifying because of the relatively short distance the nerve has to travel & because

Prognosis

Randomized controlled trials comparing nailing & plating.
J Orthop Trauma 2000 comparing plating & nailing found that union occurred in 93% of plates & 87% of nails, with shoulder pain & ↓ ROM found in the nailing group but not the plating group.