Subtalar and Midtarsal Joints

Question 1

although this joint moves in all 3 body planes, there is 1 axis of rotation; what is the subtalar joint axis of motion

Answer 1

42° from frontal plane
16° from sagittal plane
48° in transverse plane

Question 2

basic motions of the subtalar joint are pronation and supination; what is the normal range of motion

Answer 2

around 30° in total;
20° inversion
10° eversion

Question 3

in closed kinetic chain, motion of the STJ is blocked by the ground. what effect will this have

Answer 3

the calcaneus inverts/everts but talus and leg move in response to ground reaction forces, producing rotation of the tibia

Question 4

how does the subtalar joint become a rigid lever in gait

Answer 4

resupination of the STJ with MTJ locking makes the foot into a rigid lever, in order to fascilitate forward progression in normal gait

Question 5

which bones form the midtarsal joint

Answer 5

• talus and navivular
• calcaneus and cuboid

aka chopart’s joint

Question 6

which muscles help to stabilise the MTJ in active motion

Answer 6

peroneus longus and tibialis posterior
windlass mechanism

Question 7

what is the orientation of the longitudinal axis of the midtarsal joint

Answer 7

• 15° from transverse
• 9° from sagittal
• 75° from frontal

Question 8

what is the orientation of the oblique axis of the midtarsal joint

Answer 8

• 52° from transverse plane
• 57° from sagittal plane
• 38° from frontal plane

Question 9

what position is the forefoot in if the midtarsal joint is inverted with STJ in neutral

Answer 9

forefoot varus

Question 10

what position is the forefoot in if the midtarsal joint is everted with STJ in neutral

Answer 10

forefoot valgus

Question 11

forefoot varus and valgus are bony deformities; what is a soft tissue deformity of this joint called

Answer 11

forefoot supinatus - adaption due to Davis’ Law