Capitellum fractures are rare and account for 1% of elbow fractures.
Injuries to the capitellum are usually a result of axial loading of the capitellum by forces transmitted through the radial head, the lateral trochlear ridge and the lateral half of the trochlea.
Capitellum fractures are frequently missed on first examination. The fracture is not obvious on anteroposterior radiographs due to shadow background of the distal humerus. A look at following xrays would explain.
The fracture is not obvious in first xray where it is quite evident in the next one.
Here is AP view. Here we do see a fragment of associated fractured medial epicondyle but fracture of capitellum is not visualized.
Here is lateral view.
These xrays are of elbow of 15 year male who had capitellum fracture after fall from bicycle.
Because capitellum is an intra-articular injury, restoration of the anatomy should be done by open reduction and internal fixation and followed by early mobilization.
Here, I describe fixation of capitellum fracture by lateral approach.
Skin incision was centered over the lateral epicondyle [prominence just above the elbow crease on side of thumb], extending above and down on lateral aspect of arm and forearm
Following dissection through the subcutaneous tissue layers, the lateral column was palpated. The forearm was pronated to move the radial nerve away from the surgical field. A flap was raised by elevating common extensor origin along with the anterior capsule and connected to Kocher interval [interval between anconeus muscle and extensor carpii ulnaris muscle] distally. This results in a continuous full-thickness anterior soft tissue flap.
Fracture site was exposed, hematoma and soft-tissue debris was removed to allow visualization of the fracture fragments.
Fracture fragments were reduced and provisionally fixed with k-wires.
The terminally threaded Herbert screws/ cannulated cancellous screws directed posterior to anterior were used to fix the fracture.
Distal thread was buried beneath the articular surface.
Because this particular fracture also had comminution, supplemental fixation with minifragment screws was used to reconstruct in the reconstruction.
The capitello-radial articulation is maintained in this preoperative picture. Fragment of medial epicondyle was left as such.
Here are the xrays AP and lateral views, taken in the follow up.
The xrays show well united fracture and alignment.