Mayo Classification of Olecranon Fractures

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The Mayo (Morrey) classification was described by Bernard Morrey at the Mayo Clinic. It is the most widely used system for olecranon fractures and is built on three clinical assessments performed on the injury radiographs and confirmed on the table: displacement, ulnohumeral joint stability, and comminution.

The classification guides treatment through a decision ladder from non-operative care to tension-band wiring, plate fixation, and fragment excision — each matched to the fracture morphology.

Understanding why one fixation method is chosen over another is tested in the viva and in the written examination.

• The 2 mm displacement threshold is arbitrary. Many surgeons use 2 mm as the boundary between non-operative and operative treatment, but there is no high-level evidence that exactly 2 mm (rather than 1 mm or 3 mm) is the definitive cut-off. Use clinical judgement alongside the number: a young manual worker with 2 mm of articular step may benefit from fixation, whereas a frail elderly patient with 3 mm and a stable joint might reasonably be managed non-operatively.
• Stability assessment is operator-dependent. The distinction between Type II and Type III requires the elbow to be examined under anaesthesia or fluoroscopy, which is not always documented in retrospective series. Inter-observer agreement for the stable versus unstable distinction is moderate at best.
• The classification does not account for associated injuries. Coronoid fractures, radial head fractures, collateral ligament injuries, and Monteggia-equivalent patterns all affect prognosis and treatment but are not captured by the Mayo system. A Type III olecranon fracture is frequently part of a more complex elbow instability pattern that the classification alone does not describe.
• The comminution subcategory (A versus B) is inconsistently applied. There is no formal definition of how many fragments constitute comminution. Surgeons use it as a guide to fixation strategy rather than as a strict binary divider.
• TBW versus plate remains debated in practice. Biomechanical and clinical studies show plate fixation is stronger and has a lower reoperation rate, but TBW remains a valid, low-cost option for the right fracture pattern (simple transverse, good bone quality, adequate distal fragment). Choice depends on surgeon experience, patient factors, and fracture morphology rather than a rigid rule.
• Excision outcomes are patient-dependent. Triceps strength and elbow extension power decline measurably after olecranon excision. Reserve this option for patients who can tolerate some loss of extension strength — elderly, sedentary, or those with low upper-limb demands.