Anatomical variants complicating the posterior approaches towards the elbow joint

Abstract

Introduction: Anatomical variants observed during the posterior approach to the elbow joint require special attention due to their clinical relevance. We aim to present a compendious review of described variants potentially encountered during the posterior approach towards the elbow joint to the experts in the elbow surgery.

Methods: A narrative review of surgical and anatomical textbooks, as well as search of scientific databases was carried out.

Results: Variability of the subcutaneous nerves is important during incision planning. Accessory muscles such as dorsoepitrochlearis, chondroepitrochlearis, epitrochleoanconeus, subanconeus or supernumerary flexor carpi ulnaris may confuse even the senior surgeon during the dissection and possibly complicate the fracture reduction. Some bony variants such as supratrochlear foramen may lead to fracture or possibly interfere with the osteosynthesis placement. Accessory bones are also present in the region of the elbow joint. Those situated intra-articular may present with symptoms.

Conclusion: Many variants can be encountered in the area of the elbow joint and their knowledge is essential to truly understand its anatomy. The presented review enables easier orientation in the current literature with the aim on the posterior approach towards the elbow joint.

Keywords: Accessory bones; Chondroepitrochlearis; Dorsoepitrochlearis; Epitrochleoanconeus; Posterior approach; Subanconeus; Ulnar nerve; Variability around elbow joint.

Fig. 1

Variable branching of the first branch from the ulnar nerve near the medial epicondyle—a proximal to the medial epicondyle, b at the condylar level, and c below the medial epicondyle

Fig. 2

Origins and insertions of four described variable muscles around the elbow joint—dorsoepitrochlearis muscle a may insert on (1) lateral epicondyle or (2) olecranon, chondroeptirochlearis muscle, b usually inserts on medial epicondyle. Epitrochleoanconeus muscle, c originates from medial epicondyle and inserts on olecranon. Subanconeus muscle, d inserts on the dorsal aspect of the joint capsule

Fig. 3

Modified Bhadarwaj’s classification of the FCU muscle variations a type I: single muscle with two tendons, b type II: two heads forming separate muscles and type III: completely accessory muscle with c “FCU-like” insertion and d “PL-like” insertion

Fig. 4

Three relevant described accessory bones encountered around the elbow joint—a tricipital sesamoid bone, b posterior supratrochlear bone, and c anterior supratrochlear bone

Fig. 5

The supratrochlear foramen