Complications of Midshaft Humerus Fractures
Radial nerve palsy is the most common and significant complication of midshaft humerus fractures, occurring in up to 18% of cases, with most cases resolving spontaneously within 3-4 months.
Neurological Complications
Radial Nerve Injury
- Most common nerve injury associated with humeral shaft fractures 1
- Incidence: 11-18% of all midshaft humerus fractures
- Mechanism: Direct injury, entrapment during fracture, or stretching
- Clinical presentation:
- Wrist drop
- Inability to extend fingers at metacarpophalangeal joints
- Sensory loss over the dorsal first web space
- Management approach:
Other Nerve Injuries
- Ulnar nerve: Less common with midshaft fractures, more common with distal humeral fractures 3
- Median nerve: Rare in isolated midshaft fractures
- Axillary nerve: More common with proximal humeral fractures 3
Bone Healing Complications
Nonunion
- Increasing incidence with conservative management 5
- Risk factors:
- Fracture displacement >50%
- Spiral or oblique fracture patterns
- Soft tissue interposition
- Inadequate immobilization
- Infection
- Management: Typically requires surgical intervention with plate fixation or intramedullary nailing
Malunion
- Angular deformity >20° in any plane
- Rotational deformity >30°
- Shortening >3 cm
- Functional impact: Decreased range of motion, cosmetic deformity, potential for late nerve impingement
Vascular Complications
- Brachial artery injury: Rare but serious complication requiring immediate attention
- Signs of vascular compromise:
- Diminished or absent pulses
- Pale, cool extremity
- Prolonged capillary refill
- Expanding hematoma
- Requires immediate surgical exploration if present after reduction 6
Soft Tissue Complications
Muscle Entrapment
- Biceps or brachialis muscle interposition can prevent adequate reduction
- May contribute to nonunion or malunion
Joint Stiffness
- Shoulder and elbow stiffness due to prolonged immobilization
- Prevention: Early controlled mobilization as soon as pain allows 7
- Rehabilitation protocol:
- Initial phase (0-2 weeks): Sling immobilization with pendulum exercises
- Early mobilization phase (2-6 weeks): Progressive active-assisted range of motion
- Strengthening phase (6-12 weeks): Progressive resistive exercises 7
Post-Treatment Complications
Hardware-Related Issues (if surgically treated)
- Implant failure
- Screw loosening
- Hardware prominence
- Infection (1-2% of cases)
Refracture
- More common after hardware removal
- Risk factors: Early hardware removal, inadequate bone healing
Long-Term Complications
Chronic Pain
- Post-traumatic arthritis (shoulder or elbow)
- Complex regional pain syndrome
- Myofascial pain
Functional Limitations
- Decreased range of motion
- Weakness
- Impaired activities of daily living
Management Considerations
- Regular radiographic follow-up at 1,3, and 6 weeks to monitor fracture alignment 7
- Assessment of bone health and osteoporosis management in older patients 7
- Surgical intervention indicated if:
- Fracture displacement increases during follow-up
- Complete detachment of fracture fragments occurs
- Significant functional limitations develop despite adequate conservative management 7
- For radial nerve palsy, surgical exploration recommended if no recovery after 16-18 weeks of observation 2
Prevention of Complications
- Appropriate initial fracture management (surgical vs. conservative)
- Early controlled mobilization to prevent stiffness
- Regular follow-up to detect early complications
- Bone health optimization in osteoporotic patients
- Careful protection during healing phase to prevent refracture
Understanding these potential complications allows for appropriate monitoring, early intervention, and improved outcomes for patients with midshaft humerus fractures.