Biomechanics

Question 1

Where does the STJ axis lie relative to the cardinal planes?

Answer 1

8 degrees from the transverse plane and 20-30 degrees from the frontal plane. From a dorsal view, this line would enter the lateral calcaneus and exit at the medial aspect of the 1st MTPJ. From a lateral view, the line would enter the inferior calcaneus and exit dorsally just proximal to the midtarsal joint.

Question 2

What are the two axes of the midtarsal joints?

Answer 2

The oblique axis and the longitudinal axis.

Question 3

How is the longitudinal axis of the midtarsal joint situated relative to the cardinal planes and the foot?

Answer 3

Deviates 15 deg from the transverse plane and 9 deg from the sagittal plane. From a dorsal view, the axis enters the middle of the calcaneus and exits at the medial 1st MTPJ. From a lateral view, it enters the middle of the calcaneus and exits at the tarso metatarsal joints.

Question 4

What movements can occur about the longitudinal axis of the midtarsal joint? What is the ROM of this joint?

Answer 4

Inversion and eversion of the forefoot, ~4-6 degrees of motion

Question 5

How is the oblique axis of the midtarsal joint situated relative to the cardinal planes and the foot?

Answer 5

Deviates 52 deg from the transverse plane and 56 deg from the sagittal plane. From a dorsal view, it enters at the calcaneo-cuboid joint and exits at the navicular. From a lateral view, it enters inferior to the calcaneus and exits proximal to the calcaneocuboid joint

Question 6

What types of motions are capable at the oblique axis of the midtarsal joints? What is the expected ROM?

Answer 6

Dorsiflexion with abduction and plantarflexion with adduction. Expected ROM is 22 degrees.