Femoral neck fractures can occur as a result of low energy
trauma as in the elderly. Femoral neck fractures can also occur due to high
energy trauma, such as with falls or motor vehicle accidents. Anatomic
classification of femoral neck fractures includes subcapital, transcervical,
basicervical. Subcapital is common. There are two famous classifications of
subcapital fractures: Garden classification and Pauwel’s classification. Garden
classification classifies the fractures according to the amount or degree of
displacement. There are four types. It relates the amount of displacement to
the risk of vascular disruption. This classification applies to the geriatric
and insufficiency fractures.it is classified into two groups: nondisplaced are
type I and type II, and displaced are type III and type IV. Garden
classification type I is incomplete and impacted in valgus. Type II fracture is
complete and nondisplaced on at least two planes (anteroposterior &
lateral). Type III is a complete fracture and partially displaced. The
trabecular pattern of the femoral head does not line up with the acetabular
trabecular pattern. Type IV is a completely displaced fracture with no
continuity between the proximal and distal fragments. The trabecular pattern of
femoral head remains parallel with the acetabulum trabecular pattern. There are
three types within the Pauwel’s classification. Pauwel’s classification
classifies the fracture according to the orientation and direction of the
fracture line across the femoral neck. It relates to the biomechanical
stability. The more vertical the fracture, the more shear forces, and the more
complication rate. Type I has an obliquity ranging from 0-30 degrees. Type II
has an obliquity ranging from 30-50 degrees. Type III has an obliquity between
50-70 degrees or more. As the fracture progresses from Type I- Type III, the
obliquity of the fracture line increases. As the fracture line becomes more
vertical, the shear forces increase and the instability increases. A horizontal
fracture is good and stable. A vertical fracture is bad and unstable. The more
displaced the fracture, the more disruption of the blood supply and the chance
of avascular necrosis and nonunion (can occur in about 25% of displaced
fractures). If nonunion occurs in a younger patient, you may help the patient
by doing subtrochanteric osteotomy to reorient the fracture line from vertical
to horizontal (will help the fracture healing). In femoral neck fractures
associated with femoral shaft fractures, the typical neck fracture is vertical
and nondisplaced. It may require internal rotation view x-rays to see this hip
fracture (fracture could be missed). Fix the femoral neck fracture first,
followed by the femoral shaft fracture. The usual combination is parallel
screws in the femoral neck and a retrograde femoral rod for the fractured
femur. Pipkin type II fracture is fracture of the femoral head, dislocation of
the hip, and fracture of the femoral neck. Try to avoid reduction of the hip
dislocation by closed means (especially in the young patients). You may want to
do open reduction of the hip dislocation especially if the femoral neck
fracture is not displaced. Stress fracture is more common in female athletes.
It can be tension fractures. Fracture or callus is present on the superior
aspect of the femoral neck. Adult bone is weak in tension, so stress fracture
of the femoral neck needs to be fixed. This should be an emergency operation
before the fracture displaces. With compression fractures, the compression or
callus is present on the inferior aspect of the femoral neck. Some people
believe that if the compression fracture is less than 50% across the neck, then
the fracture could be stable and you can do protected crutch ambulation. If the
compression fracture is more than 50% across the neck, then the fracture is
unstable and you will do ORIF. Some surgeons fix all stress fracture of the
femoral neck. A female runner with groin pain will rule out stress fracture.
Get an MRI, and you will probably have to fix the fracture. Femoral neck
fractures can also occur due to insufficiency fracture. This occurs due to weak
bone because of osteoporosis or osteopenia. The patient will have groin pain,
pain with axial compression, and the x-ray may be normal (MRI is helpful in
diagnosing insufficiency fracture).
