Lecture 9 - Subtalar Joint (STJ)

Question 1

What articulations form the STJ?

What is it’s anatomical shape?

Answer 1

Articulation of talus & calcaneus

Convex/ concave shaped joint=
saddle shaped & very strong,

Question 2

List the 3 ligaments of the STJ

Answer 2

Talocalcaneal
Lateral Talocalcaneal [cervical]
Posterior Talocalconeal

Question 3

Where is the STJ Axis?

Answer 3

Tri-planar axis, large individual variation: average 42° from TP & 16° from SP
(With 10 degrees of rotation)

Question 4

List STJ Motion

Answer 4

pronation/ supination in foot

Converts TP plane motion of tibia to FP motion in foot

ROM: 20°inversion & 10° eversion

Frontal plane motion measurable [2:1]

Question 5

Normal gait requires how many degrees of STJ motion?

Answer 5

6°- 12° of ROM

Question 6

Why is STJ important?

Answer 6

• Pronation produces pliable foot to adapt to ground & shock absorption during gait
• Supination turns foot into rigid lever for propulsion & support
• Compensates for abnormal forefoot/ rearfoot
• STJ motion is interdependent with MTJ motion (STJ pronation increases MTJ motion & vice versa)
• Forces medial to STJ (GRF/muscle) produce supination & forces lateral to STJ produce pronation

Question 7

What is STJ neutral?

Answer 7

•Theorised position where STJ neither supinated or pronated
•2:1 ratio of inversion:eversion or supination:pronation from this position
-Pros vs cons 2:1 ratio: low reducibility amongst ppl & everyone different
•Neutral position is where foot functions most efficiently
•Varies person to person

Question 8

How is STJ neutral clinically measured?

Answer 8

Talar head palpation

Question 9

What is the motion of STJ in gait?

Answer 9

• Subject to controversy
• Pronates at heel contact & supinates at propulsion
• Root suggests foot achieves STJ Neutral position at heel lift
• Orthotic treatment aim/ backbone is to align STJ to neutral

Question 10

What is the OKC motion of STJ in pronation & supination?

non weight bearing

Answer 10

DEAb
(DF, eversion & abduction) of calcaneus
in pronation

PlAd
(PF & Adduction) of calcaneus
in supination

Question 11

What is the CKC motion of STJ in pronation & supination?

weight bearing

Answer 11

PAd of talus & Eversion of calcaneus in pronation

DAb of talus, Inversion of calcaneus in supination