Ulnohumeral Joint

articulatio humeroulnaris

The ulnohumeral joint is the primary hinge articulation of the elbow, formed between the trochlea of the humerus and the trochlear notch of the ulna (the deep sigmoid notch with its coronoid and olecranon processes as the bony grips). It allows flexion-extension of the elbow (0-145 degrees) and is the most congruent and inherently stable component of the elbow joint.

Region: Forearm

Clinical Relevance

Clinical Notes

The ulnohumeral joint is the site of the terrible triad injury (coronoid fracture, radial head fracture, lateral ligament rupture from posterior elbow dislocation), where multiple stabilisers fail simultaneously producing profound elbow instability. The coronoid process is the critical bony buttress for the ulnohumeral joint during posterior loading; even small anteromedial coronoid facet fragments can produce varus posteromedial rotatory instability. Ulnohumeral arthroplasty (interpositional or total elbow replacement) restores joint function in severe post-traumatic and rheumatoid ulnohumeral arthrosis.

Pathology

Common Injuries & Conditions

Terrible Triad Elbow Injury at Ulnohumeral Joint

Posterior elbow dislocation with coronoid fracture and radial head fracture disrupts all three stabilisers of the ulnohumeral joint (the bony coronoid, the lateral ligament, and the radial head buttress), producing persistent posterior instability requiring ORIF of coronoid and radial head fractures with lateral ligament repair.