Humeral Fracture Fixation/Knowledge Review

This module allows medical officers and surgeons who are not orthopedic specialists to become confident and competent in irrigation and debridement, powered and manual drilling, positioning and correctly inserting Schanz screws, and constructing the rod-to-rod modular frame as part of external fixation procedures for open humeral shaft fractures performed in regions without specialist coverage. To maximize patient safety, this module teaches learners to use a powered drill to insert self-drilling Schanz screws through the near cortex and then manually advance Schanz screws into the far cortex to avoid plunging.

Learning Objectives[edit | edit source]

By the end of this module, learners will:

1. Know how to avoid injuring the two nerves that can be damaged when operating on the humeral shaft when the patient is in a supine position.
2. Know how to apply the Gustilo Open Fracture Classification to open humeral shaft fractures
3. Understand how the Gustilo Open Fracture Classification impacts the selection of antibiotic therapy for open humeral shaft fractures
4. Know the principles of surgical care and management for open humeral shaft fractures
5. Know the indications for modular external fixation for a patient with an open humeral shaft fracture
6. Know the indications for referral of a patient with an open humeral shaft fracture to a tertiary center for specialist care
7. Know the acceptable parameters for reduction of open humeral shaft fractures

Anatomy Review[edit | edit source]

Axillary Nerve[edit | edit source]

• The axillary nerve runs dorsolaterally around the humeral neck (metaphysis), approximately 5-7 cm below the acromion.^[1] Therefore, the far Schanz screw in the proximal fragment must be inserted at least 7 cm below the acromion to avoid damaging the axillary nerve.

Radial Nerve[edit | edit source]

• In the middle third of the humeral shaft, the radial nerve is in close relationship with the dorsal diaphyseal cortex and can be damaged.^[2] Therefore, the near Schanz screw of the proximal fragment in the middle third of the humeral shaft should be placed in the anterolateral region of the diaphysis to avoid damaging the radial nerve.
• In the distal third of the humeral shaft, the radial nerve is in close relationship with the lateral diaphyseal cortex and must be identified through directly visualization or palpation prior to Schanz screw insertion when a lateral incision is made in a patient in the supine position.^[3]

Additional Resources[edit | edit source]

• AO Surgery Reference: Safe Zones in the Humerus for Percutaneous Pins or Screws
• Radial Nerve

Gustilo Open Fracture Classification[edit | edit source]

Gustilo Open Fracture Classification^[4][5]

Gustilo Type I:	An open fracture with a wound less than 1 cm long and clean.
Gustilo Type II:	An open fracture with a laceration more than 1 cm long without extensive soft tissue damage, flaps, or avulsions.
Gustilo Type IIIA:	Adequate soft-tissue coverage of a fractured bone despite extensive soft-tissue laceration or flaps, or high-energy trauma irrespective of the size of the wound.
Gustilo Type IIIB:	Extensive soft-tissue injury loss with periosteal stripping and bone exposure. This is usually associated with massive contamination.
Gustilo Type IIIC:	Open fracture associated with arterial injury requiring repair.

The Gustilo Open-Fracture Classification impacts the selection of antibiotic therapy for open humeral shaft fractures:

• Antibiotics based on Gustilo Classification

Antibiotic Therapy[edit | edit source]

All patients should be managed with intravenous antibiotics immediately at the time of presentation to the emergency department.^[6][7][8] Antibiotics may be changed, added or extended depending on clinical findings. Doses will be adjusted based on patient weight when indicated.

Recommended Antibiotic Therapies for Open Fractures*	Injury Characteristics	Systemic Antibiotic Regimen	Penicillin Allergy
Gustilo Type I and II	Cefazolin 2 g IV immediately and q8 hours for a total of 3 doses[6][7][8]	Clindamycin 900 mg IV immediately and q8 hours for a total of 3 doses
Gustilo Type III	Ceftriaxone 2 g IV immediately for a total of 1 dose, and Vancomycin 1 g IV immediately and q12 hours for a total of 2 doses	Aztreonam 2 g IV immediately and q8 hours for a total of 3 doses, and Vancomycin 1 g IV immediately and q12 hours for a total of 2 doses
Farm or fecal contamination	Add Penicillin G IV (e.g., 5 million-10 million units/24 hours)[6][7]	Add Metronidazole IV
Freshwater or saltwater contamination	Add Levofloxacin IV or Ciprofloxacin IV[8]	Add Levofloxacin IV or Ciprofloxacin IV[8]

Principles of Management of Open Humeral Shaft Fractures[edit | edit source]

• AO Surgery Reference: Principles of Management of Open Fractures
• Open Fractures Management
• Humeral Shaft Fractures
• Acute and Chronic Humeral Shaft Fractures in Adults
• Humeral Shaft Fractures
• Humeral Shaft Fractures

Indications for Modular External Fixation for an Open Humeral Shaft Fracture[edit | edit source]

After completing the entire module, learners should be able to perform modular external fixation of open humeral shaft fractures with the following features:

• Gustilo Type II or Gustilo Type IIIA open humeral fracture; and
• Non-comminuted, humeral shaft (extra-articular) fracture

Indications for Referral to a Tertiary Center for Specialist Care[edit | edit source]

• Non-palpable radial pulse
• Symptoms consistent with acute compartment syndrome
• Gustilo Type IIIB or Gustilo Type IIIC open humeral fracture
• Comminuted or segmental humeral fracture
• Bilateral humerus fractures
• Metaphyseal humeral fracture with intra-articular extension
• Concomitant ipsilateral or contralateral forearm fracture
• Severe traumatic brain injury (Glasgow Coma Scale <12)
• Severe spinal cord injury (lower extremity paresis/paralysis)
• Severe burns (involving >10% of the total body surface area or >5% of the total body surface area with full-thickness or circumferential injury)

Reduction Parameters for an Open Humeral Shaft Fracture[edit | edit source]

The acceptable reduction parameters for open humeral shaft fractures are:

• > 50% bone apposition
• < 15° malrotation (at 0° of rotation the patient's palm is facing straight up towards the ceiling when the patient is supine and the forearm is supinated)
• < 20° anterior angulation
• < 30° varus/valgus angulation
• < 3 cm limb shortening (cannot be measured intraoperatively)^{[9][10][11][12][13][14][15]}

Acknowledgements[edit | edit source]

This work is funded by a grant from the Intuitive Foundation. Any research, findings, conclusions, or recommendations expressed in this work are those of the author(s), and not of the Intuitive Foundation.

References[edit | edit source]