It is the most congruous joint in the body with good bony capture. The distal humerus is shaped into two complex prominences called trochlea and capitellum which articulate with the Olecranon and the radial head respectively. Stability is also increased by the medial and lateral collateral ligaments and the capsule.
For reasonable function 30 to 130 degrees flexion-extension of the elbow is needed for daily activities. Similarly 50 degrees pronation and supination is required for most activities.