Femur
Histology
Compact bone
The cortex of the femur contains mostly compact bone1. The compact bone tissue is “dense” and “unyielding,” and thus can withstand large loads especially shear and torsional forces1.
Cancellous bone
Cancellous bone is a relatively porous and spongy bone tissue that is made up of 3D trabecular lattices which span the inside of the femur1. Cancellous bone gives the femur its elastic properties, allowing it to repeatedly absorb external forces1.
Due to Wolff’s Law, cancellous bone will concentrate along lines of stress, resulting in defined trabecular networks1. The trabeculae is separated into the medial trabecular network and arcuate trabecular network1.
Osteologic features
Femoral head
The femoral head can be found just inferior to the middle 1/3 of the inguinal ligament1.
The femoral head is covered by articular cartilage except for the fova1.
Load-Absorption
The femur can withstand the high repetitive forces due to walking and other activities via its composition of compact bone and cancellous bone1.
Angle of Inclination (AoI)
The angle of inclination refers to the angle between the femoral neck and medial femoral shaft in the frontal plane1.
| Stage of Development | Angle of Inclination |
|---|---|
| Birth | 165-170 °1 |
| 2-8 y/o | Decreases by 2 °/yr1 |
| Adulthood | 125 °1 |
| Name | Angle |
|---|---|
| Coxa vara | <125 °1 |
| Normal | 125 °1 |
| Coxa Valga | >125 °1 |
Femoral Torsion
Femoral torsion refers to the relative twist between the femur’s shaft and neck in the transverse plane1.
Retroversion | <8 °1 |
Normal | 8-20 ° anteversion1 |
Excessive Anteversion | >20 °1 |
Femoral torsion can be measured via the Craig’s Test
Landmarks
Linea Aspera
- Origin:
Intertrochanteric line
- Origin:
Intertrochanteric Crest
Quadrate Tubercle
The quadrate tubercle refers to the distal attachment of the Quadratus Femoris muscle
Lesser Trochanter
The lesser trochanter projects posterior-medially from the inferior end of the intertrochanteric crest1. The lesser trochanter serves as the insertion for the Iliopsoas muscle, and is thus indirectly related to hip flexion and vertical L/S stabilization1.
Fracture
The majority of femoral fractures occur at the femoral neck in elderly individuals with predisposing conditions such as osteoporosis2.
Femoral shaft fracture can occur, but are less common and require extreme amounts of force, such as a motor vehicle accident2.