Approach to Radius and Ulna shaft fractures

Courtesy: Prof Nabil Ebraheim, University of Toledo, Ohio, USA

Overview

• Fractures of the radius and ulna shaft require careful surgical exposure to achieve accurate reduction and fixation.
• Several standard approaches are used depending on the location of the fracture along the bone.
• Each approach utilizes specific intermuscular planes while protecting important nerves and blood vessels.

Approach to the Ulna Shaft

General Characteristics

• The ulna is largely subcutaneous along most of its length, which allows relatively direct surgical access.
• Exposure is usually performed through a dorsal approach.

Surgical Interval

• The exposure is developed between the flexor carpi ulnaris muscle and the extensor carpi ulnaris muscle.
• This interval provides safe access to the shaft of the ulna.

Important Structure to Protect

• When exposing the distal third of the ulna, the dorsal cutaneous branch of the ulnar nerve must be protected.
• This nerve typically emerges approximately five centimeters proximal to the wrist joint and crosses toward the dorsal surface of the hand.

Surgical Approaches to the Radius Shaft

Exposure of the radius can be achieved through either a volar approach or a dorsal approach, depending on the fracture location.

Volar Approach to the Radius

Skin Incision

• The incision begins approximately one centimeter lateral to the insertion of the biceps tendon.
• It extends distally toward the radial styloid.

Distal Intermuscular Interval

• The distal dissection is performed between:
  • Flexor carpi radialis muscle
  • Brachioradialis muscle

Proximal Intermuscular Interval

• As the dissection proceeds proximally, the interval changes to lie between:
  • Pronator teres muscle
  • Brachioradialis muscle

Surgical Use

• This approach is commonly used for fractures involving:
  • The middle third of the radius
  • The distal third of the radius
• It may also be used for proximal fractures in selected situations.

Structures Requiring Protection in the Volar Approach

Several neurovascular structures must be identified and protected during dissection:

• Radial artery
• Superficial branch of the radial nerve
• Palmar cutaneous branch of the median nerve

Surgeons must also consider the structures that lie beneath retractors during exposure to prevent inadvertent injury.

Modified Volar Approach Considerations

• Distally, the median nerve lies between the palmaris longus tendon and the flexor carpi radialis tendon.
• Dissection along the lateral border of the flexor carpi radialis sheath generally provides a safer pathway and reduces the risk of nerve injury.

Proximal Extension of the Volar Approach

• When the exposure is extended proximally, the surgical interval remains between:
  • Brachioradialis muscle
  • Pronator teres muscle

Important Structure at Risk

• The posterior interosseous nerve must be protected during proximal exposure.

Dorsal Approach to the Radius

Skin Incision

• The incision begins just anterior to the lateral epicondyle of the humerus and extends distally along the dorsal aspect of the forearm.

Surgical Interval

• The intermuscular plane lies between:
  • Extensor carpi radialis brevis muscle
  • Extensor digitorum communis muscle

Deep Dissection

• The supinator muscle lies between these muscles and must be carefully split to reach the radial shaft.

Important Structure in the Dorsal Approach

• The posterior interosseous nerve emerges from the supinator muscle.
• This nerve must be clearly identified and protected to avoid motor deficits.

High-Risk Region

• The nerve is particularly vulnerable at the junction of the middle and proximal thirds of the radial shaft.

Summary of Common Surgical Intervals

Ulna Exposure

• Interval between:
  • Flexor carpi ulnaris
  • Extensor carpi ulnaris

Volar Approach to the Radius

Proximal region

• Interval between:
  • Brachioradialis
  • Pronator teres

Distal region

• Interval between:
  • Brachioradialis
  • Flexor carpi radialis

Dorsal Approach to the Radius

• Interval between:
  • Extensor carpi radialis brevis
  • Extensor digitorum communis

Nerve Supply Patterns of the Forearm

Dorsal Forearm Muscles

• Most muscles on the dorsal aspect of the forearm are supplied by the radial nerve or its branch, the posterior interosseous nerve.

Volar Forearm Muscles

• Most muscles on the volar aspect are supplied by the median nerve.

Important Exceptions

• Flexor carpi ulnaris is supplied by the ulnar nerve.
• The ulnar half of the flexor digitorum profundus is also supplied by the ulnar nerve.

Key Surgical Principle

• When approaching the radius from the volar side, the surgical plane is generally located between muscles supplied by different nerves, typically between muscles supplied by the median nerve and those supplied by the radial nerve.
• On the dorsal side of the forearm, most muscles share radial nerve supply, so careful identification of deeper structures such as the posterior interosseous nerve is essential.