This cadaveric biomechanics study tested how much of the proximal ulna can be removed before the ulnohumeral joint becomes unstable. Using eight fresh specimens loaded in distraction, compression, and rotation at both extension and 90° flexion, it questioned the classic teaching that up to 80% of the olecranon can be safely excised.
The classic McKeever and Buck teaching says you can excise up to 80% of the olecranon without compromising stability. This paper is the biomechanical counterpoint: constraint is linearly proportional to remaining articular surface, so the proximal olecranon carries more of the stability load than that rule implies.
The practical mental model is that stability is not held in reserve by the distal fragment. Each quarter you resect removes a proportional share of ulnohumeral constraint.
When you do excise for a comminuted fracture, the anterior band of the medial collateral ligament and the coronoid become your safety net. If the MCL is deficient, triceps tension alone will not hold the joint, and instability follows.
Know the residual restraints too: after olecranon loss, the anterior capsule resists varus-valgus in extension and the radial head resists compression in flexion. This is why preserving the radial head and MCL matters in the badly damaged elbow.
This cadaveric biomechanics study tested how much of the proximal ulna can be removed before the ulnohumeral joint becomes unstable. Using eight fresh specimens loaded in distraction, compression, and rotation at both extension and 90° flexion, it questioned the classic teaching that up to 80% of the olecranon can be safely excised.
The classic McKeever and Buck teaching says you can excise up to 80% of the olecranon without compromising stability. This paper is the biomechanical counterpoint: constraint is linearly proportional to remaining articular surface, so the proximal olecranon carries more of the stability load than that rule implies.
The practical mental model is that stability is not held in reserve by the distal fragment. Each quarter you resect removes a proportional share of ulnohumeral constraint.
When you do excise for a comminuted fracture, the anterior band of the medial collateral ligament and the coronoid become your safety net. If the MCL is deficient, triceps tension alone will not hold the joint, and instability follows.
Know the residual restraints too: after olecranon loss, the anterior capsule resists varus-valgus in extension and the radial head resists compression in flexion. This is why preserving the radial head and MCL matters in the badly damaged elbow.