Kapitel 60 – Fractures of femur Flashcards
What regions of the proximal femur are included in intracapsular and extracapsular fractures re-spectively?
Intracapsular: epiphysis, physeal, subcapital and transcervical fractures
Extracapsular:
basilar neck, intertrochanteric and subtrochanteric.
Name the fracture classifications according to the picture
a. Supracondular
b. Physeal
c. Unicondylar
d. Bicondylar
Is splinting or bandaging recommended while waiting for surgical repair?
No, it does not provide adequate immobilization and can instead result in greater fracture displacement, increased soft tissue trauma and intensified pain.
Define the inclination angle and its range
The angle between the femoral neck axis and the anatomical axis of femur in the frontal plane.
Ranges from 130-145 degrees (120-135 in chapter 59)
Define the Anteversion angle and its range
aThe angle created by the position of the femoral head with respect to the di-aphysis of femur in the transvers plane. It correlates with the degree of femo-ral torsion.
Range from 27-32 degrees.
Which muscles attaches to the greater trochanter?
Middle and deep gluteral muscle and piriformis muscle.
(superficial gluteal muscle inserts at the third throchanter).
What muscles attaches in the trochanteric fossa? And what is this fossa a landmark for?
Internal and external obturator muscle and gemelli muscle.
Used as a proximal landmark for insertion of IM pins.
Name the extraosseous arteries supplying the femoral head and neck
Medial and lateral circumflex arteries, caudal and cranial gluteal arteries and iliolumbar arteries.
The medial and lateral circumflex and caudal gluteal form an extracapsular vascular ring that lies at the base of the femoral head.
When does the proximal femoral physis close? Which one of the is responsible for the longitudinal growth of the femur?
Dogs: closure starts at 6 month and is complete by 9-12 month
Cats: closure occurs between 7 and 10 month
The capital physis is responsible for longitudinal growth (25% of the total length)
Name the approaches to the proximal femur
- Craniolateral approach
- Dorsal approach via osteotomy of greater trochanter (Gorman approach)
- Dorsal approach via tenotomy of gluteal muscles (should be reserved for ani-mals younger than 3-5 month)
- Ventral approach (provides limited exposure of the femoral head)
What are the landmarks for implant placement within the femoral head and neck? Is the technique normograd or retrograde? How many pins should be placed?
The proper insertion point is located caudal and distal to the greater trochanter within the subtrochanteric region.
The ideal insertion angle is parallel to the femoral neck and follows the angles of inclination and anteversion.
Normograde
A minimum of two pins and not more than three, in a parallel fashion.
How does the shear forces affect the healing or post-op outcome in fractures of the femoral neck?
Shear stresses at the fracture are minimal when the fracture plane is 30 de-grees or less to the transverse plane (transverse to the anatomic axis of the femur).
Steeper fracture lines (>30 degrees) result in greater shear forces and are po-tentially associated with a greater incidence of implant failure and nonunion.
What is the most common type of greater trochanter fracture and how should they be treated?
Salter-Harris type I fractures that occur as avulsion fractures in immature an-imals.
If minimally displaced the fractures can be managed conservative with cage rest for 3-4 weeks. If considerably displaced the fracture should be treated with pin and tension band. (lag screw and antirotational pin can be used but is not recommended)
Describe the first screw placements when plating a subtrochanteric fractures
The first and most important screw is the transcervical screw, placed oblique-ly in the second or third proximal hole. This provided stability of the entire proximal segment.
What is the apple core effect, when does it typically occur and why?
It is resorption of the femoral neck following open reduction and internal fixation. It has been reported in up to 70% of cases and is typically occur within 3-6 weeks after surgery.
Disruption of the vascular network supplying the femoral head and neck and overfixation, resulting in vascular disruption and stress protection, are thought to be responsible for this complication.
