Parasagittal fractures of the distal condyles of Mc/Mtlll originate from pathological defects in the palmar aspect of the distal condyles of the third metacarpal or metatarsal bone. The majority involve linear fissures in the mineralised cartilage andsubchondral bone, which arise in either the medial or lateral condylar groove [1]. The pathological origin of these fissures remains elusive although there is evidence that some may be developmental while others result from coalescence of fatigue-induced microdamage [2,3]. The remainder originate from larger, focal defects in the subchondral bone that are located more centrally within the condyle, associated with palmar osteochondral disease (POD) lesions. Whatever the origin of the defects, they are likely to be associated with fatigue damage of underlying subchondral bone. The defects act as flaws, which concentrate stress, thereby further accelerating the rate of damage accumulation and crack growth.Once the initial crack reaches a critical length it will propagate explosively. Orientation of trabeculae in the distal condyles provides little resistance to crack growth and tends to guide the fracture proximally.
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