Orthopedic Guide: Kocher and Kaplan Surgical Approaches to the Elbow
Key Takeaway
The Kocher posterior approach is vital for posterior elbow pathologies like distal humerus and olecranon fractures, focusing on ulnar nerve safety. The Kaplan anterolateral approach offers access to the radial head and capitellum, crucial for radial head fractures. Both are fundamental for orthopedic surgeons to achieve optimal outcomes in elbow trauma and reconstruction.
A 45-year-old male presents following a high-energy fall onto an outstretched hand. Radiographs and CT scans reveal a complex, comminuted distal humerus fracture involving both the medial and lateral columns with intra-articular extension. You are preparing for an open reduction internal fixation (ORIF) via a posterior approach. Describe your surgical exposure strategy and how you would mitigate the risk of iatrogenic injury.
Candidate: I would place the patient in the lateral decubitus position. I’d use a posterior midline incision and perform an olecranon osteotomy to get the best view of the articular surface. I must identify and protect the ulnar nerve early, neurolysing it from the cubital tunnel and transposing it anteriorly at the end. I’d use dual plates, either parallel or perpendicular, to fix the columns.
Candidates often forget the "first step" of ulnar nerve protection, failing to emphasize that it must be identified before any deep dissection occurs. Many also struggle to justify the choice between a triceps-sparing (Bryan-Morrey) and an olecranon osteotomy, or fail to mention pre-drilling the osteotomy site, which is crucial for anatomical reduction and stable re-fixation.
A structured response is essential: 1) Positioning: Lateral decubitus allows for gravitational assistance and full elbow ROM. 2) Nerve Safety: Routine identification and neurolysis of the ulnar nerve prior to any deep dissection is non-negotiable. 3) Exposure: I would choose an olecranon osteotomy for maximum articular visualization, ensuring it is a chevron-shaped cut proximal to the coronoid fossa, and I would pre-drill to facilitate hardware re-fixation (tension band or lag screw). 4) Reconstruction: I would prioritize articular restoration first (using K-wires/screws), then secure the columns using orthogonal (perpendicular) or parallel plating to achieve a "truss" construct, which is biomechanically superior for these complex injuries.
You are managing a displaced Mason type II radial head fracture. You choose the Kaplan anterolateral approach. What is the most critical anatomical structure at risk, and how do you protect it during your dissection?
Candidate: The PIN is at risk. It runs through the supinator. I need to be careful when dissecting down to the radial head and avoid splitting the muscle too far distally to avoid hitting the nerve.
Failing to mention the Arcade of Frohse and ignoring the importance of the internervous plane (ECRB and EDC). Simply saying "be careful" is not a high-scoring surgical description.
The Posterior Interosseous Nerve (PIN) is the critical structure. It typically enters the supinator muscle approximately 3-4 cm distal to the radiocapitellar joint. To protect it, I utilize the internervous interval between the Extensor Carpi Radialis Brevis (ECRB) and the Extensor Digitorum Communis (EDC). During deep dissection, I perform subperiosteal elevation of the supinator off the radial neck to keep the PIN protected within the muscle mass. I also avoid excessive traction and cautery in the region of the Arcade of Frohse. If necessary, I would position the forearm in maximum pronation to move the radial neck away from the PIN pathway.
