Question

1. Discuss the functional anatomy of the hip.
   

2. Discuss the normal Angle of Inclination of the adult hip and potential compensation patterns seen with excessive varus or valgus angles.
   

3. Discuss the normal Femoral Torsion Angle of the adult hip and potential compensation patterns seen with excessive anterior or posterior angulation.
   

4. Discuss 3 planes of closed chain hip osteokinematics.
   

5. Discuss the osteokinematics of contra-directional lumbopelvic movements in the sagittal and frontal planes.
   

Answer 1

Human hip joint is a ball and socket synovial joint. Hip joint is built to stand and walk. It has the largest range of motion after shoulder joint. However, it is a quite static joint due to surrounding bones, muscles and ligaments.

* Hip joint is formed by the articulation between acetabulum of pelvis and head of the femur. It forms a connection from the lower limb to the pelvic girdle, and thus is designed for stability and weight-bearing.

The hip joint consists of the head, which forms proximal femur, neck, greater and lesser trochanter and proximal femoral shaft along with acetabulum composed of the fusion of ilium, ischium, and pubis.

- Hip joint is a diarthrodial joint with its inherent stability dictated primarily by its osseous components or articulations.

- Primary function of hip joint is to provide dynamic support the weight of the body while facilitating  force and load transmission from the axial skeleton to the lower extremities, allowing mobility.

- Hip joint typically works in a closed kinematic chain.

# Motions Available - The hip joint allows for movement in three major axes, all of which are perpendicular to one another.

- The location of the centre of the entire axis is at the femoral head.

- The transverse axis permits flexion and extension movement.

- The longitudinal axis, or vertically along the thigh, allows for internal and external rotation.

- The sagittal axis, or forward to backward, allows for abduction and adduction.

# Ligaments and joint capsules - In general, the hip joint capsule is tight in extension and more relaxed in flexion.
* The capsular ligaments include -

- Iliofemoral ligament

- Pubofemoral ligament

- Ischiofemoral ligament (strongest ligament in the body)

- Ligamentum teres

* Joint Capsules - The hip joint is extremely strong, due to its reinforcement by strong ligaments and musculature, providing a relatively stable joint. The hip joint capsule is a substantial contributor to joint stability. The capsule is thicker anterosuperiorly where the predominant stresses of weight bearing occur, and is thinner posteroinferiorly.

# Labrum - The labrum forms a fibrocartilagenous extension of the bony acetabulum, mostly composed of type 1 collagen that is typically between 2-3mm thick. It lines the acetabular socket and attaches to the bony rim of the acetabulum. It has an irregular shape, being wider and thinner anteriorly and thicker posteriorly. On the anterior aspect, the labrum is triangular in the radial section. On the posterior aspect, the labrum is dimensionally square but with a rounded distal surface.

Labrum has three surfaces - Internal and external articular surface, and basal surface.

* Nerve supply of hip joint -

The hip joint receives innervations from the femoral, obturator, superior gluteal nerves.

* Blood supply - Numerous variations in the blood supply to the hip.

- Most common is medial and lateral circumflex femoral arteries.

- Profunda femoris (branch of femoral artery)

- Foveal artery

- There are two significant anastomoses. The cruciate anastomosis supports the upper thigh and the trochanteric anastomosis, which supports the head of the femur.

### Angle of inclination of hip -

The angle of inclination is defined as the angle resulting from the intersection of a line down the long shaft of the femur and a line drawn through the neck of the femur.

Typically, the normal adult has an angle of inclination between 120 and 125 degrees, it usually is closer to 125 in the elderly. An increase in this angle greater than 125 degrees, results in coxa valga, and a decrease is called coxa vara.

A varus deformity is an excessive inward angulation (medial angulation, that is, towards the body's midline) of the distal segment of a bone or joint. The opposite of Varys is called valgus.

### Angle of torsion is the angle through which a radial section of a body (as a wire or a shaft) deflects from its normal position when the body is subjected to torque.

Angle of torsion of hip is formed by looking at the relationship between the axis of the femoral head and neck and the femoral condyles. Normal femur has an angle of torsion between 12 and 15 degrees. An increase in this angle is termed anteversion, while a decrease in this angle, is termed retroversion.

## List of common patterns of compensation -

- Pronation distortion syndrome

- Valgus knee

- Patellofemoral Tracking syndrome

- Patellofemoral pain syndrome

- Quad dominance

- Asymmetrical weight shift

- Glute amnesia syndrome

- Buttwink

- Posterior pelvic tilt

- Anterior pelvic tilt

- Lower cross syndrome -

## Three versions of osteokinematics -

Osteokinematics are the gross movements of bones at joints.

- flexion / extension - movement of femur straight anteriorly towards pelvis is flexion and movement of femur straight posteriorly away from the pelvis is extension.

- adduction / abduction - movement of femur laterally to side away from midline is abduction and movement of femur medically towards midline is adduction.

- internal rotation and external rotation - rotary movement of femur laterally around its longitudinal axis away from midline is external rotation and rotary movement of femur medically around its longitudinal axis towards midline is internal rotation.

• The transverse axis permits flexion and extension movement.

• The longitudinal axis, or vertically along the thigh, allows for internal and external rotation.

• The sagittal axis, or forward to backward, allows for abduction and adduction.

## Osteokinematics of contra directional lumbopelvic movements in the sagital and frontal planes -

Anterior & posterior pelvic rotation – sagittal or anteroposterior plane
• Right & left lateral rotation – lateral or frontal plane