Presentation
Fall on an outstretched left arm. Pain, swelling, and restriction of motion of the elbow. No neurovascular deficit.
Patient Data
The lateral film demonstrates :
- joint effusion
- articular cartilage separation (coronal shear fracture) with very little subchondral bone attached, with anterior displacement
- a minimally displaced radial head fracture
Features consistent with a Kocher-Lorenz fracture (type II capitellum fracture, according to Bryan and Morrey classification with McKee modification), with an undisplaced fracture through the lateral aspect of the radial head.
- yellow arrow: type II capitellum fracture (Kocher-Lorenz fracture)
- blue arrow: type I radial head fracture
Case Discussion
Concomitant capitellar and radial head fractures occur with falls on an outstretched hand with the elbow extended or partially flexed. This association of injuries is frequently missed leading to elbow stiffness, chronic pain, intra-articular loose bodies, malunion, and nonunion.
According to Bryan and Morrey classification (with McKee modification), there are four types of capitellum fractures:
- type I (Hahn-Steinthal): large fragment containing substantial subchondral bone
- type II (Kocher-Lorenz): sleeve fracture with minimal bone
- type III: comminuted fracture
- type IV: fracture including a major portion of the trochlea
In this case, it is a Kocher-Lorenz capitellum fracture (type II) and radial head fracture type I according to the Mason classification.