Kocher approach to the elbow and its options

Summary

The original Kocher approach was published several times in the 1892−1907 period. It extends in the interval between the extensor carpi ulnaris and the anconeus and consists in subperiostal release of the lateral collateral ligament (LCL), joint capsule and origin of extensors at the lateral epicondyle and their retraction anteriorly, and a similar release of the anconeus from the distal humerus and its reflection posteriorly. This provides an extensive approach to the elbow. Today this approach is described in the textbooks in various modifications that have little in common with the original description except for the fact that dissection is made in the so called Kocher interval between the extensor carpi ulnaris and the anconeus. Therefore it is often called a limited Kocher approach.

The study describes our modification of the Kocher approach that we use primarily in fractures of the head and neck of the radius, in certain fractures of the distal humerus, and also in irreducible dislocations and certain fracture-dislocations of the elbow.

The incision is made along the line connecting the lateral epicondyle of the humerus and the border between the proximal and middle thirds of the ulna. The incision is pulled open and the strong, white opalescent common extensor fascia incised in order to identify the interval between the extensor carpi ulnaris and the anconeus. The two muscles are separated by thin vascularized fatty connective tissue which is split in order to expose a typical tendon reinforcing the upper half of the anterior margin of the anconeus. In this phase it is beneficial to detach the origin of the extensor carpi ulnaris from the lateral epicondyle. It facilitates retraction of the extensor carpi ulnaris anteriorly and of the anconeus slightly posteriorly. In contrast with the original Kocher approach, we do not release the anconeus from the lateral epicondyle of the humerus.

The muscles are retracted to expose the anterolateral surface of the joint capsule and to identify the course of the LCL complex. The capsule is incised along the anterior margin of LCL, starting from the lateral epicondyle up to and including the radial annular ligament. Arthrotomy performed anterior to LCL spares the insertion of the lateral ulnar collateral ligament on the ulna and, consequently, preserves the elbow stability. If dissection more distally is required in order to expose the radial neck, part of the supinator must be incised as well. In such case the forearm is first carefully pronated as much as possible, as a result of which the canalis supinatorius including the deep branch of the radial nerve will move anteriorly, thus reducing the risk of injury to the nerve.

The capsule is incised and opened, revealing the anterolateral surface of the head of humerus and radial head. In this phase it is beneficial to flex the elbow to 90−100 degrees, when the anterior part of the capsule will get flabby and allow a better visualization of the joint. The joint capsule must be released from the distal humerus together with extensors originating at the lateral epicondyle of humerus. This will considerably improve visualization of the anterior part of the joint cavity. During wound closure the common extensor fascia must be firmly sutured, as it is a significant but often underestimated stabilizer of the lateral part of the elbow.

The extended option of the Kocher approach consists in retraction of the anconeus proximally. It is indicated in certain fracture-dislocations of the proximal forearm, i.e. fractures of the radial head and the entire proximal ulna. After dissection of the whole anconeus, this muscle is detached from the ulnar shaft and entirely reflected proximally. The muscle remains attached by its short proximal margin to the lateral epicondyle of humerus and to olecranon. This eliminates the risk of injury to the neurovascular hilus of the muscle, as the motoric nerve enters the muscle in the middle of its upper border. Retraction of the muscle exposes both the lateral surface of the joint capsule and the lateral surface of the proximal ulna. Further procedure, i.e. incision of the capsule and inspection of the joint, is the same as in the limited Kocher approach.

Key words:
Kocher approach − modified Kocher approach − radial head fractures – fracture dislocations of the elbow