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Bone Healing — MFDS Part 1 MCQ

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HardPhysiologyBone HealingMFDS Part 1

A simple mandibular body fracture is anatomically reduced and secured with compression plating. The construct produces absolute stability, negligible interfragmentary strain and direct cortical contact without a residual fracture gap. Which healing pattern is most characteristic if union proceeds uneventfully?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: C — Primary contact healing, with osteonal remodelling crossing the fracture line and little or no external callus

Explanation lettering: E = shown as A · A = shown as C · C = shown as E

The correct answer is A. Anatomical reduction with interfragmentary compression creates absolute stability and direct cortical contact, permitting primary contact healing. Osteoclast-led cutting cones and subsequent osteonal remodelling cross the fracture line, so little or no external callus is expected. Secondary healing (B) requires relative stability and proceeds through callus formation, including a cartilaginous phase and endochondral ossification. Primary gap healing (C) can occur under stable fixation but requires a small residual gap, which the stem excludes. Distraction osteogenesis (D) requires controlled progressive separation of an osteotomy. Hypertrophic non-union (E) reflects inadequate mechanical stability and produces excessive callus rather than direct union.

Reference: Beeharry MW, Ahmad B. Principles of Fracture Healing and Fixation: A Literature Review. Cureus. 2024;16(12):e76250. https://pubmed.ncbi.nlm.nih.gov/39717521/