3 - Zill - Joints of Lower Extremity

Question 1

Synovial Joints

What do some of these joints have to further reduce friction?

Answer 1

Hip / Knee / Ankle

Joints with synovial membrane, that secretes lubricating synovial fluid

• -

Articular Discs - lay between cartilage heads of joint, further reduces friction

Question 2

Articular Cartilage

What can be a clinical presentation of issues with these?

Answer 2

Cartilage layer on bones at point of contact, serves as shoch absorber and reduces effects of friction on the bones

Osteoarthritis - degeneration of articular cartilage

Question 3

Intrinsic vs Accessory Ligaments

Answer 3

Intrinsic = thickening of capsule (hip ligaments)

Accessory = Separate from capsule (collateral ligaments of knee)

Question 4

Shape of Acetabulum and Labrum

What is the Y-shaped convergence point of the ilium, ischium, and pubis?

Answer 4

Acetabulum = “C” Shaped (Lunate Articular Surface)

Has a gap inferiorly called the acetabular notch

- - -

Acetabular Labrum - deepens cavity with rim of cartilage

Triradial Cartilage

Question 5

What ligament bridges the acetabular notch?

What covers the surface of the acetabulum and femur head?

Answer 5

Transverse Acetabular Ligament

Hyaline Cartilage

Question 6

What encloses the hip joint?

What is their main role?

Answer 6

3 x Intrinsic Ligaments - Limit Extension

1. Iliofemoral Ligament (limits extension)
2. Pubofemoral Ligament (limits extension, abdution)
3. Ischiofemoral Ligament (limits extension)

Question 7

Strongest ligament in the body? Purpose?

Answer 7

Iliofemoral Ligament

O: Ilium

I: Intertrochanteric Line

Action: Prevents over extension

Question 8

Ligament of Head of Femur

Answer 8

Located inside joint capsule, attached to head at fovea capitis and to transverse acetabular ligament

Transmits artery of ligament of head of femur (branch of Obturator artery)

Question 9

Types of Hip Dislocations:

Congenital

v

Traumatic

v

Fracture

Answer 9

Congenital: Superior, Medial Rotation

Traumatic: Posterior

Fracture: Lateral Rotation (risk for avascular necrosis of head of femur)

Question 10

What is blood source for the head of the femur?

Answer 10

1. Obturator Artery (through ligament head)
2. Medial and Lateral Femoral Circumflex

Question 11

Bursae of Knee

Answer 11

1. Suprapatellar Bursa - Outpocketing of synovial cavity of knee joint posterior to quadriceps tendon (largest)
2. Prepatellar bursa - Between skin and patella (patella)
3. Superficial Infrapatellar Bursa - Between skin and patellar ligament (low)

Question 12

Housemaid’s Knee

v

Clergyman’s Knee

Answer 12

Housemaid’s - Prepatellar Bursitis (higher)

Clergyman’s - Superficial Infrapatellar Bursitis (lower)

Clergy = Superficial In’friar’patellar

Question 13

Extracapsular Ligaments:

Lateral Collateral Ligament

Medial Collateral Ligament

Answer 13

LCL - Prevents movement of tibia medially

MCL - Prevents movement of tibia laterally

Opposite side restriction!

Question 14

Intracapsular Ligaments:

Anterior Cruciate Ligament

Posterior Cruciate Ligament

Answer 14

ACL - Passes up and back (front view); prevents anterior tibia movement

PCL - Passes up; prevents posterior tibia movement

ACL/PCL prevent same as name!

Question 15

Test for tears in Cruciate (ACL/PCL) ligaments?

Answer 15

ACL - Draw tibia anteriorly (Lachman)

PCL - Push tibia posteriorly

Question 16

Menisci

Answer 16

“C” shaped cartilages that are attached to inner side of joint capsule

• -

Medial Mediscus

Lateral Meniscus

Question 17

Medial Meniscus

&

Lateral Meniscus

Answer 17

Medial: Relatively fixed, attached to medial collateral ligament, between condyles

Lateral: More movable because NOT attached to lateral (fibular) collateral ligament

Question 18

Terrible Triad of Knee Joint Injury

Answer 18

Blow to Lateral side of knee

Tear:

MCL (medial [tibial] collateral ligament)

ACL (anterior cruciate ligament)

Medial Meniscus (it’s connected to MCL)

Question 19

Mechanism of Locking and Unlocking the Knee

Answer 19

Locking - Femur rotates medially last 30 deg; making ligaments taut ‘locking’ the knee (passive extension locks)

Unlocking - Popliteus muscle rotates femur laterally unlocks (active flextion unlocks)

Lock = passive medial rotation

Unlock = active lateral rotation

Question 20

Joints Between Tibia and Fibula

Answer 20

Syndesmosis (sheet of connective tissue between bones)

1. Interosseus Membrane - broad sheet of connective tissue between tibia/fibula w/gap for Ant. Tibial artery/vein
2. Anterior and Posterior Inferior Tibio-Fibular Ligaments - join bones above ankle joint (high ankle sprain)

Question 21

High Ankle Sprain cause

Answer 21

Tear or stretch of Anterior Inferior Tibio-fibular ligaments

Question 22

What type of joint is the ankle?

Answer 22

Uniaxial, hinge-type joint

Only permits dorsiflexion and plantar flexion

Strengthened by collateral ligaments

Question 23

Medial (Deltoid) Ligament

Answer 23

Strong, triangular shaped ligament of ankle

O: Medial Malleolus of tibia

I: Medial surface of talus / calcaneus

Action: Limits eversion

This is a strong ligament, and the reason you usually roll your ankle via inversion, NOT eversion

Question 24

Lateral Ligaments of Ankle Joint

Answer 24

Generally weaker than medial

O: Lateral malleolus of fibula

I: Anterior / Posterior Talofibular - Talus; Calcaneofibular - Calcaneus

Action: Limit inversion

These are weaker than medial, hence why you usually “roll” or sprain your ankle via inversion (these fail)

Question 25

Joints of Inversion/Eversion of Foot

Answer 25

1. **Subtalar Joint** (between Talus and Calcaneus) 2. **Transverse Tarsal Joint** (between Talus and Navicular medially, and Calcaneus and Cuboid bones laterally)

Question 26

What is damaged in an ankle sprain?

Answer 26

Excessive inversion **Anterior Talofibular, Calcaneofibular Ligament** stretched or partially torn

Question 27

Pott's Fracture

Answer 27

Excessive **eversion** of foot/ankle Deltoid Ligament is _strong_ and doesn't rupture **Medial Malleolus** and **Fibula** are **fractured** **- - -** Imagine getting hit low, from the lateral side of the ankle

Question 28

Valgus v Varus

Answer 28

Genu Valgus = "knock-kneed" Normal in infants 3-5 Genu Varus = "bow-legged" Normal in infants 0-3 **- - -** **In va**_L_**gus, **_L_**eft **_L_**eg forms and "_L_"**