3. Structure:
Plane synovial joints
Formed by the distal row of tarsal bones (posteriorly) and the bases
of the metatarsals
5 TMT joints:
1st TMT joint:
Articulation between base of 1st metatarsal & medial cuneiform
bone
Own articular capsule.
2nd TMT joint:
Articulation between base of 2nd metatarsal with a mortise formed by
the middle cuneiform bone and the sides of the medial and lateral
cuneiform bones.
4. This joint is set more posteriorly than the other tarsometatarsal joints;
it is stronger and its motion is more restricted
3rd TMT joint:
articulation between the 3rd metatarsal & lateral cuneiform
shares a capsule with 2nd tarsometatarsal joint
4th & 5th TMT joint:
bases of 4th & 5th metatarsals, with the distal surface of cuboid bone
both the joint share a common joint capsule.
5.
6. Small plane articulations exist between bases of the metatarsals to
permit motion of one metatarsal on the next.
Numerous dorsal, plantar, and interosseous ligaments reinforce each
TMT joint.
deep transverse metatarsal ligament contributes to stability of the
proximally located TMT joints by preventing excessive motion and
splaying of metatarsal heads.
9. Unique, although not fully independent, axis of motion.
Hicks examined the axes for the five rays.
Ray is defined as a functional unit formed by a metatarsal and (for
the first through third rays) its associated cuneiform bone.
The cuneiform bones are included as parts of the movement units of
the tarsometatarsal rays because of the small and relatively
insignificant amount of motion occurring at the cuneonavicular
joints.
10. The cuneonavicular motion, therefore, becomes functionally part of
the available tarsometatarsal motions.
4th & 5th rays are formed by the metatarsal alone because these
metatarsals both articulate with the cuboid bone.
Most motion occurs at 1st & 5th rays.
Each axis is oblique and triplanar of the tarsometatarsal joints
1st has the largest ROM.
11. Axis of 1st ray is inclined in such as way that :
dorsiflexion with inversion and adduction
Plantarflexion with eversion and abduction.
The abduction/adduction components normally are minimal.
Movements of 5th ray around its axis are more restricted and occur
with the opposite arrangement of components:
Dorsiflexion with eversion and abduction
Plantarflexion with inversion and adduction
12. The axis for 3rd ray nearly coincides with a coronal axis; the
predominant motion, therefore, is dorsiflexion/ plantarflexion.
Axes for 2nd & 4th rays were intermediate between the adjacent axes
for 1st & 5th rays.
2nd rays move around an axis that is inclined toward, but is not as
oblique as, the first axis.
4th ray moves around an axis that is similar to, but not as steep as, 5th
axis.
2nd ray is considered to be the least mobile of the five.
13. Function:
Interdependent motion
TMT joints contribute to hollowing and flattening of the plantar
surface of the foot
greatest relevance of TMT joint motions is found during weight-
bearing.
In weight-bearing, the tarsometatarsal joints function primarily to
augment the function of the transverse tarsal joint.
14. TMT joints attempt to regulate position of the metatarsals and
phalanges (the forefoot) in relation to the weight-bearing surface.
when the hindfoot position is at an end point in its available ROM or
the transverse tarsal joint is inadequate to provide full compensation,
the tarsometatarsal joints may rotate to provide further adjustment of
forefoot position.
16. 1st & 2nd rays – dorsiflex, invert
4th & 5th rays – plantarflex, invert
Which results in a supination (inversion) twist of the TMT joints to
attempt to adequately adjust the forefoot to the ground.
17.
18.
19. Pronation Twist:
Subtalar joint supination results,
Calcaneal - inversion
Talus - dorsiflexion and abduction
Transverse tarsal joint - supinated
Navicular and cuboid bones – carried along with the hindfoot
motion
20. 1st & 2nd rays - plantarflex and evert
4th & 5thrays - dorsiflex and evert
Result in a pronation (eversion) twist of the TMT joints in an
attempt to adjust the forefoot adequately.
24. 5 MTP joints
Condyloid synovial joints
Two degrees of freedom:
extension/flexion (or dorsiflexion/plantarflexion)
abduction/adduction
During walking (late stance phase), toe extension at the MTP joints permits
the foot to pass over the toes, whereas metatarsal heads and toes help balance
the superimposed body weight through activity of the intrinsic and extrinsic
toe flexor muscles.
25. Structure
The MTP joints are formed by,
proximally - convex heads of the metatarsals
distally - concave bases of the proximal phalanges
Structure of MTP joints is analogous to the structure of MCP joints,
with a few exceptions.
Unlike MCP joints, range of MTP extension exceeds range of MTP
flexion.
All metatarsal heads bear weight in stance.
26. Consequently, articular cartilage must remain clear of the weight-
bearing surface on the plantar aspect of metatarsal head.
This structural requirement restricts the available range of MTP
flexion.
Also in contrast to the hand, there is no opposition available at 1ST
TMT joint; the first toe (hallux) moves exclusively in the same
planes as the other four digits.
1ST MTP joint has 2 sesamoid bones , located - plantar aspect of 1ST
metatarsal head
In neutral position of 1st MTP joint, the sesamoid bones lie in two
grooves, separated by intersesamoid ridge on metatarsal head.
27. Ligaments associated with sesamoid bones form a triangular mass
that stabilize the sesamoid bones within their grooves.
Sesamoid bones serve as anatomic pulleys for the flexor hallucis
brevis muscle and protect the tendon of the flexor hallucis longus
muscle from weight-bearing trauma.
The flexor hallucis longus is protected as it passes through a tunnel
formed by the sesamoid bones and the intersesamoidal ligament that
connects the sesamoid bones across their plantar surfaces.
Unlike the sesamoid bones of the thumb, the sesamoid bones of the
1st metatarsal absorb weightbearing stress, along with the relatively
large quadrilaterally shaped first metatarsal head.
28. With toe extension greater than 10°, the sesamoid bones no longer
lie in their grooves and may become unstable.
Chronic lateral instability of the sesamoid bones may lead to
metatarsophalangeal deformity.
Stability of joints is provided by a joint capsule, plantar plates,
collateral ligaments, and the deep transverse metatarsal ligament.
Plantar plates are structurally similar to volar plates in hand.
29. Fibrocartilaginous structures in the four lesser toes are each
connected to the base of proximal phalange distally and blend with
the joint capsule proximally.
Plates of the 4 lesser toes are interconnected by deep transverse
metatarsal ligament and plantar aponeurosis.
Collateral ligaments of MTP joints are similar to MCP joint, have
two components:
Phalangeal portion that parallels the metatarsal and phalange,
Accessory component that runs obliquely from the metatarsal head
to plantar plate.
30. Plantar plates protect the weight-bearing surface of metatarsal heads
&, with collateral ligaments, contribute to stability of the MTP
joints.
Each plantar plate, serves as a central stabilizing structure with a
fibrocartilaginous composition that allows it to withstand
compressive loads.
At 1st MTP joint, the sesamoid bones and thick plantar capsule are in
place of the plantar plates found at the other toes
31.
32. Function:
Two degrees of freedom
Flexion/Extension motion > Abduction/Adduction motion
Extension motion exceeds flexion motion
MTP motions occur in weight-bearing or non-weightbearing
MTP joints serve primarily to allow the weight-bearing foot to rotate
over the toes through MTP extension (known as the metatarsal
break) when rising on the toes or during walking.
33. MTP Extension & Metatarsal Break
Metatarsal break that occurs at MTP joints as the heel rises,
metatarsal heads & toes remain weightbearing.
Its occurs as MTP extension around a single oblique axis that lies
through 2nd to 5th metatarsal heads.
Inclination of the axis is produced by the diminishing lengths of the
metatarsals from the second through the fifth toes and varies among
individuals.
The angle of the axis around which the metatarsal break occurs may
range from 54° to 73° with respect to the long axis of the foot.
34. The range of MTP extension will vary,
Depending on amount of dorsiflexion/plantarflexion motion at TMT
joint, age & whether, the motion is assessed in weight-bearing or
non weight-bearing.
According to study, 1st MTP joint extension averaged 81° in a
younger population (mean age of 21 years) compared to 56º in an
older population (mean age of 80 years).
Another studies have reported averages ranging between 36° and
65° of MTP extension during walking.
Limited extension ROM at the 1ST MTP joint will interfere with the
metatarsal break and is known as hallux rigidus.
35. Heel raise occurs during weight–bearing due to active contraction of
plantarflexor muscles.
Most of the plantarflexion muscles also contribute to supination of
the subtalar and transverse tarsal joints.
Plantarflexion musculature normally cannot lift the heel completely
unless the joints of the hindfoot and midfoot are supinated and
locked so that the foot can become a rigid lever from the calcaneus
through the metatarsals.
This rigid lever will then rotate (“break”) around the MTP axis.
36. As MTP joint extension occurs, the metatarsal heads glide in a
posterior and plantar direction on the plantar plates and the
phalanges that are stabilized by the supporting surface.
The metatarsal heads and toes become the base of support, and the
body’s line of gravity must move within this new and more limited
base to remain stable.
The obliquity of the axis for the metatarsal break allows weight to be
distributed across the metatarsal heads and toes more evenly than
would occur if the axis were truly coronal.
If the body weight passed forward through the foot and the
metatarsal break occurred around a true coronal MTP axis, an
excessive amount of weight would be placed on the first and second
metatarsal heads.
37. These two toes would also require a disproportionately large
extension range.
Obliquity of the axis of metatarsal break shifts the weight laterally,
minimizing the large load on the first two digits
38. MTP Flexion, Abduction, and Adduction
Flexion ROM at MTP joints can occur to a limited degree from
neutral position but has relatively little purpose in the weight-
bearing foot other than when the supporting terrain drops away
distal to the metatarsal heads.
Most MTP flexion occurs as a return to neutral position from
extension.
However, toe flexor musculature is quite important and should be
distinguished from the functionally less relevant MTP flexion ROM.
Abduction and adduction of MTP joint appear to be helpful in
absorbing some of the force that would be imposed on the toes by
the metatarsals as they move in a pronation or supination twist.
39. The first toe normally is adducted on the first metatarsal about 15° to
19°.
An increase in this normal valgus angulation of 1ST MTP joint is
referred to as hallux valgus and may be associated with a varus
angulation of the first metatarsal at the tarsometatarsal joint, known
as metatarsus varus.
41. Synovial hinge joints
One degree of freedom: flexion/extension.
Great toe has only 1 IP joint connecting two phalanges, whereas the
four lesser toes have 2 IP joints (proximal and distal IP joints)
connecting three phalanges.
The toes function to smooth the weight shift to the opposite foot in
gait and help maintain stability by pressing against the ground in
standing.
Injuries to the interphalangeal joints are relatively uncommon but
may be involved in dislocations and fractures.
