bubble_chart Overview

The humeral shaft is defined as the region from 1 cm distal to the surgical neck of the humerus to 2 cm proximal to the humeral condyle. Humeral shaft fractures are most common in young adults, with the middle third being the most frequently affected site, followed by the distal third, while the proximal third is the least common. Fractures of the middle and distal third are prone to radial nerve injury, and fractures of the distal third are more likely to result in nonunion.

bubble_chart Etiology

(1) Direct violence often occurs in traffic and industrial accidents, mostly seen in the middle third, with comminuted or transverse fractures.

(2) Indirect violence results from falls with the palm or elbow hitting the ground, mostly seen in the lower third, with oblique or spiral fracture lines.

(3) Rotational violence frequently occurs during recruit throwing training, commonly affecting the middle to lower third, with spiral fracture lines.

bubble_chart Pathogenesis

The displacement of a humerus shaft fracture is not only related to the direction of the force and the gravity of the limb but also directly influenced by muscle contraction. When the fracture is located in the upper part of the humeral shaft, above the insertion point of the deltoid muscle, the proximal fragment is pulled forward and inward by the pectoralis major, latissimus dorsi, and teres major muscles, while the distal fragment is pulled upward and outward by the deltoid muscle. For a mid-shaft humeral fracture, where the fracture site is below the insertion point of the deltoid muscle, the proximal fragment shifts outward and forward due to the contraction of the deltoid and coracobrachialis muscles, while the distal fragment moves upward due to the contraction of the biceps and triceps brachii muscles. In the case of a lower humeral shaft fracture, the muscle pull on both ends is relatively balanced, and the direction of displacement depends on the external force, the position of the limb, and gravity.

bubble_chart Clinical Manifestations

Fracture presents with localized swelling, possible shortening, angular deformity, severe localized tenderness, abnormal movement, and bone crepitus, with limited upper limb mobility. When combined with radial nerve injury, symptoms such as wrist drop may occur.

bubble_chart Diagnosis

Obvious history of trauma, pain in the affected limb, and limited movement. X-ray can determine the location and displacement of the fracture.

bubble_chart Treatment Measures

1. Non-displaced fracture

includes closed transverse, short oblique, comminuted, or linear non-displaced fractures without nerve injury. No anesthesia is required, and gentle manipulation can be used to correct angular or rotational deformities. External fixation methods can be selected based on specific conditions and circumstances: a. Light long-arm hanging gypsum or upper arm "U"-shaped gypsum with a triangular sling to suspend the forearm; b. Small splintage; c. Long-arm gypsum with an abduction brace or shoulder spica gypsum fixation; d. Single-arm external fixation frame. Gypsum fixation is maintained for 6 weeks, and external fixation is removed after X-rays show initial callus formation, followed by limb movement exercises. For those with external fixation frames, joint movement can be initiated early.

2. Displaced fracture

requires manual reduction under brachial plexus or local hematoma anesthesia, followed by small splint or external fixation frame fixation. When conditions permit, closed reduction and locked intramedullary nail fixation can also be performed under fluoroscopy with a TV X-ray machine.

3. Fracture combined with radial nerve injury

: If the fracture is non-displaced, the nerve is likely contused. After fracture external fixation, observe for 1–3 months. If the nerve does not recover, surgical exploration is performed. For fractures with significant displacement, the radial nerve may be trapped between the fracture ends, and manual reduction should not be attempted to avoid nerve rupture. Surgical exploration of the nerve should be performed, along with open reduction and internal fixation of the fracture.

4. Open reduction and internal fixation

is suitable for open fractures within 8 hours of injury, where thorough debridement minimizes the risk of infection; closed medial malleolus fractures with soft tissue interposition between fracture ends that cannot achieve functional reduction through manual methods or multiple-segment humeral fractures; multiple bone and joint injuries in the same limb; fractures combined with vascular injury or fractures with significant displacement combined with radial nerve injury; and nonunion or severe malunion fractures. For those treated with plate and screws, reliable external fixation is still required postoperatively. For those treated with compression plates, locked intramedullary nail internal fixation, or external fixation frames, early functional exercise can be initiated.