Simple extraarticular fractures may be oblique, spiral or transverse.
Careful inspection of radiographs should be undertaken to ensure that intraarticular extensions are not missed. Traction radiographs, oblique radiographs, or a CT scan may help to elucidate occult articular extensions. Surgeons should always be aware that it may not be until during surgery that an occult intraarticular extension is discovered and that they may need to deal with such a fracture by reducing the articular surface using a lag screw technique.
Oblique or spiral
These fractures can result from relatively low energy, twisting forces to distal femur. They are often seen in osteoporotic, elderly patients.
X-ray taken from Orozco R et al, (1998) Atlas of Internal Fixation. Used with kind permission.
These fractures can result from higher energy injuries in younger patients.
X-ray by courtesy of Spital Davos, Switzerland, Dr C Ryf and Dr A Leumann.