Hip Dislocations - Orthopaedic Trauma - Lecture Slides, Slides of Orthopedics

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Hip Dislocations

Anatomy:

Hip Joint

Ball and socket joint. Femoral head: slightly asymmetric, forms 2/3 sphere. Acetabulum: inverted “U” shaped articular surface. Ligamentum teres, with artery to femoral head, passes through middle of inverted “U”.

Joint Contact Area

Throughout ROM:

• 40% of femoral head is in contact with acetabular articular cartilage.
• 10% of femoral head is in contact with labrum. Docsity.com

Acetabular Labrum

Strong fibrous ring

Increases femoral head coverage

Contributes to hip joint stability Docsity.com

Hip Joint Capsule

• Extends from intertrochanteric ridge of proximal femur to bony perimeter of acetabulum
• Has several thick bands of fibrous tissue

Iliofemoral ligament

• Upside-down “Y”
• Blocks hip extension
• Allows muscle relaxation with standing

Femoral Neck Anteversion

• Averages 7^0 in Caucasian males.
• Slightly higher in females.
• Oriental males and females have been noted to have anteversion of 14 0 and 16 0 respectively. Docsity.com

Blood Supply to Femoral Head

1. Artery of Ligamentum Teres
   • Most important in children.
   • Its contribution decreases with age, and is probably insignificant in elderly patients. Docsity.com

Blood Supply to Femoral Head

2. Ascending Cervical Branches
   • Arise from ring at base of neck.
   • Ring is formed by branches of medial and lateral circumflex femoral arteries.
   • Penetrate capsule near its femoral attachment and ascend along neck.
   • Perforate bone just distal to articular cartilage.
   • Highly susceptible to injury with hip dislocation. Docsity.com

Sciatic Nerve

Composed from roots of L4 to S3. Peroneal and tibial components differentiate early, sometimes as proximal as in pelvis. Passes posterior to posterior wall of acetabulum. Generally passes inferior to piriformis muscle, but occasionally the piriformis will split the peroneal and tibial components

Hip Dislocation: Mechanism of Injury

Almost always due to high-energy trauma.

Most commonly involve unrestrained occupants in MVAs.

Can also occur in pedestrian-MVAs, falls from heights, industrial accidents and sporting injuries. Docsity.com

Posterior Dislocation

• Generally results from axial load applied to femur, while hip is flexed.
• Most commonly caused by impact of dashboard on knee. Docsity.com

Type of Posterior Dislocation depends on:

Direction of applied force.

Position of hip.

Strength of patient’s bone.

Hip Position vs. Type of Posterior Dislocation

In General,

Abduction: fracture-dislocation

Adduction: pure dislocation

Extension: femoral head fracture-dislocation

Flexion: pure dislocation

Mechanism of

Anterior

Dislocation

Extreme abduction with external rotation of hip.

Anterior hip capsule is torn or avulsed.

Femoral head is levered out anteriorly.

Effect of Dislocation on Femoral Head Circulation

When capsule tears, ascending cervical branches are torn or stretched.

Artery of ligamentum teres is torn.

Some ascending cervical branches may remain kinked or compressed until the hip is reduced.

Thus, early reduction of the dislocated hip can improve blood flow to femoral head.

Associated Injuries

Mechanism: high-energy, unrestrained occupants

Thus, associated injuries are common:

• Head and facial injuries
• Chest injuries
• Intra-abdominal injuries
• Extremity fractures and dislocations

Associated Injuries

Mechanism: knee vs. dashboard Contusions of distal femur Patella fractures Foot fractures, if knee extended Docsity.com

Associated Injuries

Sciatic nerve injuries occur in 10% of hip dislocations.

Most commonly, these resolve with reduction of hip and passage of time.

Stretching or contusion most common.

Piercing or transection of nerve by bone can occur.

Classification

Multiple systems exist.

Many reflect outmoded evaluation and treatment methods.

Thomas and Epstein Classification

of Hip Dislocations

Most well-known

Type I Pure dislocation with at most a small posterior wall fragment.

Type II Dislocation with large posterior wall fragment.

Type III Dislocation with comminuted posterior wall.

Type IV Dislocation with “acetabular floor” fracture (probably transverse + post. wall acetabulum fracture-dislocation).

Type V Dislocation with femoral head fracture.

AO/OTA Classification

• Most thorough.
• Best for reporting data, to allow comparison of patients from different studies.
• 30-D10 Anterior Hip Dislocation
• 30-D11 Posterior Hip Dislocation
• 30-D30 Obturator (Anterior-Inferior) Hip Dislocation

Evaluation: History

Significant trauma, usually MVA.

Awake, alert patients have severe pain in hip region.

Physical Examination: Classical Appearance

Posterior Dislocation: Hip flexed, internally rotated, adducted.

Physical Examination: Classical Appearance

Anterior Dislocation: Extreme external rotation, less-pronounced abduction and flexion.

Unclassical presentation (posture) if:

• femoral head or neck fracture
• femoral shaft fracture
• obtunded patient