Lecture 11 - Forefoot Joints

Question 1

Which structures for the 1st Ray?

Answer 1

1st metatarsal & cuneiform

= functional anatomical unit

Question 2

Motion of 1st Ray?

Answer 2

DF with inversion & PF with eversion

Question 3

Motion of 1st Ray in gait?

Answer 3

DF with foot pronation &

PF in propulsion to enable normal MPJ extension

Question 4

How many degrees of DF is required by hallux, to allow propulsion in gait?

Answer 4

70° dorsiflexion

Question 5

What type of joint is the hallux?

Answer 5

ginglymo-arthrodial joint

a joint having the form of a hinge & sliding joint, via the sesamoids

Question 6

If abnormal parabola/toe length present what will occur & what conditions may this lead to?

Answer 6

1st ray PF may not occur. If 2nd met too long, it contacts ground & 1st ray loading doesn’t occur properly.

May lead to 1st MPJ subluxation (arthritis, one toe joined to another) hallux limitus & rigidus.

1st proximal phalanx jams into metatarsal head. Smashes every time by proximal phalanx because not sliding underneath.

Question 7

Plantarflexed/ Dorsiflexed 1st Ray is caused by?

Answer 7

Weak gastrocnemius
(main plantarflexar of foot)

Hypertonicity of peroneus longus
(Working harder & PF 1st ray due to insertion on 1st met)

Weak tibialis anterior
(flexors have mechanical advantage, pull in Pflexed position)

2° to uncompensated forefoot varus (not enough STJ motion & hallux in air, 1st ray constant flexion & plantar flexed 1st ray)

Weak intrinsic muscles -> dorsiflexion of hallux (should be holding toes straight)

Question 8

Rigid PF 1st Ray is associated with which foot type & conditions?

Answer 8

• Associated with cavus foot type
• Callus under sub metatarsal 1 & 5
• Associated with sesamoiditis, inversion sprains, tibial stress fracture, medial knee pain, lower back pain

Question 9

What occurs with a DF 1st Ray (Metatarsal Primus Elevatus)?

Answer 9

1st Ray doesn’t PF- jamming occurs and hallux limitus/rigidus

Question 10

Causes of DF 1st Ray (Metatarsal Primus Elevatus)?

Answer 10

Congenital or acquired

TA hypertonicity, weak peroneus longus or Ffoot supinatus

Question 11

What is Hallux Abducto Valgus?

Answer 11

• Acquired subluxation of 1st MPJ

* Hypermobility, instability

Question 12

Causes of HAV?

Answer 12

Hypermobile 1st ray (STJ pronation & structural position), RA, neuromuscular disorders, post surgical malfunction

Shoe choice affects progression

Question 13

List 4 stages of HAV

Answer 13

1. Lateral displacement proximal phalanx relative to 1st met head (sublux frontal & sagittal plane)
2. Hallux abductus appears (towards 2nd met) [Adductor hallucis adds deforming force]
3. Inclination of inter-metatarsal angle between 1 & 2 (bump on medial side foot)
   As try & push off on toe, that’s angulated (during propulsion) cannot push & propel through hallux, start to roll of hallux, causing increased forces. Metatarsal starts to separate away, inter-metatarsal angle b/w 1& 2 ↑, shoe pressure occurs, bump shows.
4. Hallux partially/ completely dislocated from met head

Question 14

2nd - 4th Rays
Motion occurs in which plane?
In midstance of gait what occurs?

Answer 14

Sagittal plane motion only

In midstance of gait, rays lock at 65° dorsiflexion (on met heads)

Question 15

Explain pathomechanics of PF 1st ray

Answer 15

??