Q7-1. Intro to Arthrology

Question 1

How many joints are there between the tibia and the fibula?

Answer 1

3 joints:

• superior tibiofibular joint
• crural interosseous membrane
• tibiofibular syndesmosis

Question 2

Which parts of which bones make up the superior tibiofibular joint?

Answer 2

• Tibia: articular facet on the lateral condyle
• -> faces posterior-inferior-laterally
• Fibula: articular facet on the head
• -> faces anterior-superior-medial

Question 3

What type of joint is the superior tibiofibular joint?

Answer 3

Synovial, Plane

• consists of a capsule w/ fluid
• there is joint movement

Question 4

What type of motion occurs at the superior tibiofibular joint?

Answer 4

Gliding

Question 5

Which ligaments hold the superior tibiofibular joint together?
Hint: think about what type of joint this is…

Answer 5

Remember: this is a synovial joint–> there is a joint capsule

Ligaments: 2 Capsular ligaments

• Anterior Superior Tibiofibular Ligament (ASTFL)
• Posterior Superior Tibiofibular Ligament (PSTFL)

Question 6

What is clinically significant about this joint?

Answer 6

• The common peroneal nerve travels near the fibular head and can be palpated. This is important to consider if ever there is an injury to this joint.
• ASTFL can blend with the tendon to biceps femoris
• Joint can communicate w/ knee joint via a popliteal bursae

Question 7

Which parts of which bones make up the crural interosseous membrane (joint)?

Answer 7

• Tibia: lateral/interosseous border
• Fibula: medial/interosseous border
• *fibers generally run in an inferior-lateral direction

Question 8

What type of joint is the crural interosseous membrane?

Answer 8

“Well…..”

This was Dr. Myer’s explanation.

Question 9

What motion occurs at the crural interosseous membrane (joint)?

Answer 9

Essentially none.

Question 10

Which ligaments hold the crural interosseous membrane (joint) together?”

Answer 10

“Well….”
Interosseous membrane is connective tissue, but not really a “ligament”.
—> analogy: like a screen door- connects the two bones, but not very tough

Question 11

Is there anything clinically interesting about the crural interosseous membrane (joint)?

Answer 11

• Two perforations: superior (anterior tibial artery) and inferior (perforating peroneal artery)
• Serves to increase the surface area for origins of muscles
• Serves as a natural boundary between the anterior and posterior compartments
• can be damaged in Weber Type C ankle fractures

Question 12

Which parts of which bones make up the tibiofibular syndesmosis?

Answer 12

• Tibia: fibular notch (on lateral end of the distal tibia)

- Fibular: triangular area at the inferior end of the interosseous crest

Question 13

What type of joint is the tibiofibular syndesmosis?

Answer 13

Non-synovial–> Fibrous syndesmosis

• only constant syndesmotic joint in the body (per some sources)
• body’s way of keeping these bones tightly together and stable

Question 14

What type of motion occurs at the tibiofibular syndesmosis?

Answer 14

Essentially none, but…

• a couple millimeters of separation w/ ankle dorsiflexion–> causes the fibula to rotate externally on the tibia
• *We know there must be some motion because this area gives us so much trouble w/ respect to ankle fractures/dislocations

Question 15

What ligaments hold the tibiofibular syndesmosis together?

Answer 15

No capsule (not a synovial joint)
4 short, strong fibrous band ligaments:
- Anterior Inferior Tibiofibular Ligament (AITFL)
- Posterior Inferior Tibiofibular Ligament (PITFL); the inferior transverse ligament is the most inferior portion of the PITFL
- Interosseous Ligament
- BONUS: There is specialized soft tissue that fills in the potential space between the medial and lateral malleoli

All of these structures together form a complete “ring of tissue” that contribute to the “socket” that is the ankle joint.

Question 16

Is there anything clinically interesting about the tibiofibular syndesmosis?

Answer 16

Syndesmotic injuries:

• sprains: “high” ankle sprain
• avulsions
• ruptures

Joint can be visualized during an ankle arthroscopy.

Question 17

Which parts of which bones make up the ankle joint?

Answer 17

Tibia:

• Plafond
• Medial Malleolus–> comma shaped facet
• Squatter’s facet (anterior distal portion of tibia, there is a divet out and then in above the plafond)

Fibula:

• Triangular malleolar articular facet
• Lateral malleolar fossa

Talus:

• Talar dome
• Medial comma shaped facet
• Lateral inverted triangle ending in the lateral process

Question 18

Where would you find the “gutters” of the ankle?

Answer 18

1. Between the Talus and the Medial Malleolus

2. Between the Talus and the Lateral Malleolus

Question 19

What type of joint is the ankle joint?

Answer 19

Compound synovial; modified ginglymus; hinge joint

Question 20

What is significant about the joint capsule(s) for the ankle joint?

Answer 20

Contains both fibrous and synovial capsular membranes

• generally attached at the edges of the articular surfaces of the 3 bones
• weakest anteriorly/posteriorly
• reinforced medially/laterally (think tib/fib)

Question 21

What is significant about the posterior joint capsule of the ankle specifically?

Answer 21

Large potential space–> insulflation
Posterior communication with the FHL
Lateral communication with the peroneals (longus and brevis)

Question 22

What type of motion occurs at the ankle joint?

Hint: remember what plane/axis the ankle operates within and around

Answer 22

Dorsiflexion (w/ ABduction) & Plantarflexion (w/ ADduction)

**Essentially no inversion/eversion and NOT pronation/supination joint–> that comes in with the subtalar joints that work with the ankle

Question 23

How many ligaments hold the ankle joint together?

Answer 23

7 ligaments–> 2 ways of classifying them:

• Lateral (3) vs. Medial (4)
• Capsular (6) vs. Extracapsular (1)

Question 24

What are considered the lateral ankle ligaments?

Answer 24

• Anterior talofibular ligament (ATFL)–> shortest and weakest
• Calcaneofibular ligament (CFL)–> crosses both ankle and subtalar joints; cordlike and easy to distinguish
• Posterior talofibular ligament (PTFL)–> strongest lateral ankle ligament

**Note the lack of “tibio” in these names! What does that tell you?

Question 25

What is the only extracapsular ligament contributing to the ankle joint?

Answer 25

Calcaneofibular ligament (CFL)

Question 26

What are considered the medial ankle ligaments?

Answer 26

Deltoids: one large “fanlike” sheet of tissue running from a narrow origin on medial malleolus to the foot.

• Anterior Tibiotalar Ligament–> deepest of deltoid ligs
• Posterior Tibiotalar Ligament
• Tibiocalcaneal Ligament–> crosses both the ankle and subtalar joints; merges with the the calcaneonavicular ligament and supports the spring ligament
• Tibionavicular Ligament –> crosses both the ankle and talonavicular joints

**Note the lack of “fibular” in these names! What does that tell you?

Question 27

Is there anything clinically interesting about the ankle?

Answer 27

The ankle is the cartilaginously congruent joint in the lower extremity (considering the complex structure of the ankle socket).

The ankle ligaments tend to get injured in a sequential manner

• Deltoids: ATFL is the most commonly involved, followed by CFL
• ATFL is most taut when ankle is plantarflexed–> anterior drawer test
• CFL is most taught when the ankle is dorsiflexed–> stress inversion test

Total Ankle Arthroplasty (replacement)

Question 28

From the required reading “Changes in tibiotalar area of contact caused by lateral talar shift”:
With 1mm of lateral talar displacement, what is the average reduction in tibiotalar contact area?

Answer 28

For the first 1mm of displacement, there is a 42% decrease in contact area at the tibiotalar articulation.