Anterior Volar (Henry) Approach to the Forearm: Comprehensive Surgical Guide
Key Takeaway
The Anterior Volar (Henry) Approach is a foundational orthopedic surgical technique for the forearm, providing comprehensive access to the anterior radius and interosseous membrane. It's indispensable for managing diaphyseal and distal radius fractures, nerve decompressions, and specific soft tissue conditions, ensuring stable fixation and optimal functional outcomes.
A 35-year-old male presents with a closed displaced mid-shaft radial fracture. You are planning an open reduction and internal fixation using the Henry approach. Describe the internervous planes utilized in this approach and how you would ensure the safety of the major neurovascular structures encountered.
Candidate: The Henry approach uses the plane between the brachioradialis (radial nerve) and the FCR (median nerve). Proximal-distally, we move between the FCR and the FDS. I'd protect the radial artery by retracting it with the brachioradialis and keep the median nerve safe by ensuring it stays medial with the FDS.
Failure to mention the Anterior Interosseous Nerve (AIN). Candidates often focus only on the main median nerve and forget that the AIN is at significant risk deep to the FPL and FDP, especially when elevating the pronator quadratus or retracting the deep flexor compartment.
Structure the answer by proximal, mid, and distal segments. Proximal: Brachioradialis (Radial N) vs. Pronator Teres (Median N). Mid: FCR (Median N) vs. FDS (Median N). Distal: FCR (Median N) vs. Radial Artery (Radial side). Crucially, identify the AIN as the 'silent' danger—it branches distal to the PT and lies on the interosseous membrane. Mention the 'watershed line' to avoid FPL irritation and specify protecting the superficial branch of the radial nerve (proximally) and palmar cutaneous branch of the median nerve (distally).
During your deep dissection for a radius fracture, you encounter the deeper structures of the volar forearm. Describe the anatomical relationship of the median nerve to the surrounding musculature.
Candidate: The median nerve passes deep to the pronator teres. It then travels between the FDS and FDP before becoming more superficial in the distal forearm near the wrist, lying radial to the FDS tendons.
Inaccuracy regarding the AIN branching point. A common error is stating the AIN innervates all of the deep compartment (it does not innervate the medial half of the FDP, which is Ulnar Nerve supplied). Failing to demonstrate knowledge of the specific layers (Superficial vs. Intermediate vs. Deep) is a major loss of marks.
Systematically describe the layers: 1. Superficial: PT, FCR, PL, FCU. 2. Intermediate: FDS. The Median nerve is found deep to the PT and then deep to the FDS. 3. Deep: FPL, FDP, PQ. The AIN (branch of Median) runs on the interosseous membrane between FPL and FDP. Emphasize that the Median nerve must be traced proximally to ensure it is not tethered by the FDS arch during retraction.
You have completed the reduction of a distal radius fracture. As you move toward closure, what are the technical considerations regarding the pronator quadratus and the hardware?
Candidate: I would repair the PQ to cover the plate to avoid tendon irritation. I'd ensure the plate is proximal to the watershed line so the FPL tendon doesn't rupture.
Simply saying "fix the hardware" is insufficient. Candidates often fail to mention the fluoroscopic assessment of the distal screw tips, specifically checking for penetration into the DRUJ or the Radiocarpal joint, which can lead to catastrophic hardware failure or post-traumatic arthritis.
State that the Watershed Line is the critical boundary; placing a plate distal to this risks FPL and FDP rupture. Mention PQ Repair: it provides a soft-tissue buffer for the flexor tendons. Discuss the use of Fluoroscopic views (specifically the 'Skyline' or 10-degree tilted lateral view) to confirm that the distal screws are contained within the radial subchondral bone and not violating the joint space or DRUJ.
