Humerus Shaft Fracture: Radial Nerve Palsy, Bracing & PT MCQs

Fracture of the Humerus Shaft

Fractures of the humeral shaft are common (1-3% of all fractures). They are famous for their association with Radial Nerve palsy and the success of functional bracing.

[Image of Humerus Shaft Fracture and Radial Nerve]

1. Anatomy & Nerves

• Radial Nerve: Runs in the spiral groove directly against the posterior aspect of the bone.
• Risk: Highly susceptible to injury in middle/distal third fractures.
• Sign: Wrist Drop (inability to extend wrist/fingers).

2. Specific Types

Holstein-Lewis Fracture:
A spiral fracture of the distal 1/3 of the humerus.
High risk (22%) of Radial Nerve Palsy as the nerve gets trapped in the fracture site.

3. Management

• Conservative (Gold Standard):
  • U-Slab / Hanging Cast: Initially (1-2 weeks).
  • Functional Cast Brace (Sarmiento): Applied once swelling subsides. Uses hydrostatic pressure to align bone. Success rate >90%.
• Surgical (ORIF):
  • Open fractures.
  • Pathological fractures.
  • Vascular injury.
  • Polytrauma (floating elbow).

4. Physiotherapy

• If Radial Nerve Palsy: Apply a dynamic cock-up splint to prevent contracture. Passive ROM of wrist/fingers is crucial.
• General: Pendulum exercises early. Active elbow ROM once consolidated.

25 Practice MCQs

Q1. Which nerve travels in the spiral groove of the humerus?

Answer: A). Injury causes wrist drop.

Q2. Holstein-Lewis fracture is a fracture of:

Answer: C). Highest risk of radial nerve entrapment.

Q3. The Sarmiento brace works on the principle of:

Answer: A). Compressing the muscles aligns the bone cylinder inside.

Q4. Clinical sign of Radial Nerve palsy is:

Answer: C). Loss of wrist and finger extensors.

Q5. Most radial nerve palsies associated with closed shaft fractures are:

Answer: A). 90% recover without surgery in 3-4 months.

Q6. Which movement is preserved in a high radial nerve palsy?

Answer: B). The branch to the Triceps usually comes off *before* the spiral groove.

Q7. Hanging cast relies on:

Answer: A). The weight of the cast pulls the bone straight. Patient must sleep semi-upright.

Q8. Indications for surgery include all EXCEPT:

Answer: D). Best treated with functional bracing.

Q9. Acceptable angulation (varus/valgus) for humerus shaft is up to:

Answer: A). The shoulder and elbow have large ROM to compensate, and the arm is non-weight bearing.

Q10. "Floating Elbow" means:

Answer: A). The elbow joint is "floating" between two fractures. Requires surgical fixation.

Q11. Which splint is used for Radial Nerve Palsy?

Answer: A). Keeps wrist extended to allow functional grasp.

Q12. Average union time for humerus shaft is:

Answer: B). Slower than metaphyseal bone.

Q13. Medial winging of scapula suggests injury to:

Answer: A). Not common in shaft fracture but important differential.

Q14. Surgical approach (Plating) to the posterior humerus requires splitting which muscle?

Answer: A). Triceps splitting approach.

Q15. If radial nerve does not recover after 4-6 months, treatment is:

Answer: A). E.g., Jones transfer (Pronator Teres to ECRB).

Q16. Non-union is defined if no healing is seen by:

Answer: B). Requires bone grafting.

Q17. The Nutrient Artery of the humerus enters:

Answer: A). Fracture here can disrupt blood supply, risking delayed union.

Q18. Which muscle acts as a "pad" between the humerus and anterior vessels?

Answer: A). Protects the Brachial artery.

Q19. Intramedullary Nailing (IMN) vs Plating: Which causes more shoulder pain?

Answer: A). Nail entry point is through the rotator cuff, often causing pain.

Q20. In children, humerus shaft fractures are often:

Answer: A). Excellent remodeling potential.

Q21. The autonomous zone for Radial Nerve sensation is:

Answer: A). The area between thumb and index finger (dorsum).

Q22. Early complication of Humerus fracture is:

Answer: A). Especially in polytrauma patients.

Q23. Brachioradialis is innervated by:

Answer: A). Despite being a flexor, it is supplied by the extensor nerve.

Q24. Distraction of fracture fragments (fragments too far apart) leads to:

Answer: A). Often caused by a hanging cast that is too heavy.

Q25. Pendulum exercises can start:

Answer: A). To prevent shoulder stiffness, which is a major complication.