Kocher Approach to the Elbow (Posterolateral)

Patient Positioning

Standard Position: Supine with Arm Across Chest

• Patient supine on radiolucent table
• Arm brought across the chest with elbow flexed approximately 90 degrees
• Assistant supports the arm or use arm holder/bolster
• Tourniquet applied high on the upper arm
• Prepare and drape the entire arm including the hand

Alternative: Lateral Decubitus

• Lateral decubitus with affected arm supported on a padded bolster
• Allows gravity-assisted retraction of triceps
• Useful when combined medial and lateral exposures planned
• Ensure the elbow can be flexed and extended freely

Key Setup Points

• Confirm C-arm access for anteroposterior and lateral views of the elbow
• Ensure the forearm can be pronated and supinated during surgery
• Mark all landmarks before incision
• Have radial head replacement system available if indicated

Positioning Rationale The supine position with the arm across the chest provides excellent access to the lateral elbow while allowing the surgeon to work comfortably. The lateral decubitus position is particularly useful when the surgeon anticipates needing to address both medial and lateral pathology without repositioning the patient. In both positions, the elbow must be free to move through a full arc of flexion and extension to allow dynamic assessment of stability and reduction.

Surface Landmarks and Incision

Bony Landmarks

• Lateral epicondyle of humerus (prominent palpable point)
• Radial head (palpable in the soft spot between epicondyle and olecranon)
• Olecranon tip and posterior border of ulna
• Capitellum (deeper, less distinct)

Soft Tissue Landmarks

• Common extensor origin over lateral epicondyle
• Anconeus muscle belly (posterior to lateral epicondyle)
• Extensor carpi ulnaris (more anterior)

Skin Incision

• Longitudinal incision beginning at the lateral epicondyle
• Extend distally toward the posterior border of the ulna, approximately 6-8 cm in length
• The incision is centered over the radiocapitellar joint
• Slightly curved or straight depending on surgeon preference
• Stay posterior to the lateral epicondyle to protect the LUCL origin

Incision Planning Pearls

• The incision can be extended proximally along the lateral column of the humerus for distal humerus exposure
• Distal extension follows the ulnar border for more distal radial neck access
• Avoid placing the incision too anteriorly (risks damaging the radial nerve branches)

Landmark Accuracy The lateral epicondyle is the most reliable proximal landmark. The radial head is best palpated with the elbow in slight flexion and the forearm in neutral rotation. The posterior border of the ulna provides the distal orientation for the incision and ensures the approach stays posterior enough to protect the LUCL.

Internervous Plane

Deep Internervous Plane

• Between: Anconeus (radial nerve) and extensor carpi ulnaris (posterior interosseous nerve)
• This is a true internervous plane allowing safe muscle retraction without denervation
• The plane is identified by a thin layer of fat between the two muscle bellies

Superficial Dissection

• Incise skin and subcutaneous fat
• Identify the interval between anconeus posteriorly and extensor carpi ulnaris anteriorly
• The fat stripe is a reliable landmark
• Develop the plane bluntly with scissors or finger dissection
• The common extensor origin may be partially elevated from the lateral epicondyle

Deep Dissection

• Incise the joint capsule anterior to the lateral collateral ligament complex
• The capsulotomy must remain anterior to the LUCL to avoid iatrogenic posterolateral rotatory instability
• Expose the radial head and neck by retracting the ECU anteriorly and anconeus posteriorly
• Pronate the forearm to move the PIN away from the radial neck

Anatomical Confirmation Intraoperative confirmation of the correct interval can be achieved by observing the muscle fiber orientation. The anconeus fibers run obliquely from proximal-lateral to distal-medial, while the ECU fibers run more longitudinally. The fat stripe lies precisely between these two distinct fiber directions.

Step-by-Step Dissection

Superficial Dissection

• Incise skin and raise full-thickness flaps
• Identify the thin fat stripe between anconeus and ECU
• Develop the interval with blunt dissection
• The radial nerve branches to anconeus enter proximally and should be protected
• Partially detach the common extensor origin from the lateral epicondyle as needed

Deep Dissection and Capsulotomy

• Identify the lateral collateral ligament complex
• Make the capsulotomy anterior to the LCL insertion on the lateral epicondyle
• This protects the LUCL which lies within the posterior part of the complex
• Incise the annular ligament anteriorly to expose the radial head
• For radial neck exposure, continue subperiosteal dissection distally

Radial Head and Neck Exposure

• Pronate the forearm fully during radial neck dissection
• This rotates the PIN anteriorly and medially away from the surgical field
• The safe zone for radial head exposure is the anterolateral 90-120 degrees
• Avoid excessive retraction on the posterior structures

Structures at Risk by Layer

Deep Dissection Details After developing the muscle interval, the joint capsule is encountered. The capsule is incised in line with the muscle interval, staying well anterior to the palpable LCL complex. The annular ligament is divided at its anterior aspect to allow the radial head to be delivered into the wound. For radial neck fractures, subperiosteal elevation is continued distally while maintaining the forearm in full pronation.

Extension and Closure

Proximal Extension

• Extend the incision proximally along the lateral supracondylar ridge
• Elevate the common extensor origin and brachioradialis anteriorly
• Expose the lateral column of the distal humerus
• Useful for capitellar fractures and lateral column distal humerus fractures
• The radial nerve lies anterior in the brachialis-brachioradialis interval proximally

Distal Extension

• Extend along the posterior border of the ulna
• Develop the interval between ECU and anconeus further distally
• Limited by the PIN crossing the radial neck
• Useful for more distal radial neck fractures or Monteggia variants

Closure

• Repair the annular ligament if divided
• Reattach the common extensor origin to the lateral epicondyle with transosseous sutures or anchors
• Repair the LCL complex if partially detached
• Close the fascia loosely to avoid compartment syndrome
• Subcutaneous and skin closure in layers
• Drain if extensive dissection performed

Postoperative Protocol

• Posterior splint in 90 degrees flexion for 7-10 days
• Early active range of motion beginning at 7-10 days
• Progressive strengthening at 6 weeks
• Full activities at 3-4 months

Extension Risks Proximal extension places the radial nerve at risk in the anterior compartment. The nerve should be identified and protected if the incision extends more than 10 cm proximal to the lateral epicondyle. Distal extension increases PIN risk and requires careful subperiosteal dissection with the forearm maintained in pronation.