Talocalcaneonavicular Joint (TCN)Talocalcaneonavicular Joint (TCN) • TCN joint name ties together talonavicular TCN joint name ties together talonavicular

and talocalcaneal (and talocalcaneal (subtalar) subtalar) joints that are joints that are anatomically and functionally relatedanatomically and functionally related

• Talonavicular articulation is formed Talonavicular articulation is formed proximally by the anterior portion of the proximally by the anterior portion of the head of the talus and distally by concave head of the talus and distally by concave posterior navicularposterior navicular

Ligaments:Ligaments:

a.a. Spring ligament (plantar calcaneo Spring ligament (plantar calcaneo navicular ligament) (11)navicular ligament) (11)

b.b. Deltoid ligamentDeltoid ligament

c.c. Bifurcate ligament (lateral calcaneo Bifurcate ligament (lateral calcaneo navicular ligament) (15)navicular ligament) (15)

Joint function:Joint function: • Talus acts as a ball bearing placed Talus acts as a ball bearing placed

between the tibiofibular mortise between the tibiofibular mortise superiorly, calcaneum inferiorly and superiorly, calcaneum inferiorly and navicle anteriorlynavicle anteriorly

• Motion of the weight bearing talus at one Motion of the weight bearing talus at one end will produce motion at other endend will produce motion at other end

• Forces transmitted through the leg to the Forces transmitted through the leg to the talus are shared by each of the articular talus are shared by each of the articular surfaces that make up the TCNsurfaces that make up the TCN

• TCN joint is key to foot functionTCN joint is key to foot function

Transverse Tarsal Joint / mid tarsal joint:Transverse Tarsal Joint / mid tarsal joint:• Compound joint formed by talonavicular and Compound joint formed by talonavicular and

calcaneocuboid joint calcaneocuboid joint • Because the talonavicular joint is classically Because the talonavicular joint is classically

considered to be a part of transverse tarsal considered to be a part of transverse tarsal joint, it belongs to two joint complexes- TCN joint, it belongs to two joint complexes- TCN joint and the transverse tarsal jointjoint and the transverse tarsal joint

• Other component of transverse tarsal joint is Other component of transverse tarsal joint is calcaneocuboid jointcalcaneocuboid joint

• Two joints together present an S shaped joint Two joints together present an S shaped joint line that transects the foot horizontally line that transects the foot horizontally dividing the hind foot from midfoot and dividing the hind foot from midfoot and forefootforefoot

• Navicular and cuboid are essentially Navicular and cuboid are essentially immobile in the weight bearing footimmobile in the weight bearing foot

• Transverse tarsal joint motion therefore, is Transverse tarsal joint motion therefore, is considered to be the motion of the talus and considered to be the motion of the talus and of the calcaneum on a relatively fixed of the calcaneum on a relatively fixed naviculocuboid unitnaviculocuboid unit

Joint Structure:Joint Structure:• Talonavicular articulation is formed Talonavicular articulation is formed

proximally by the anterior portion of the head proximally by the anterior portion of the head of the talus and distally by concave posterior of the talus and distally by concave posterior navicularnavicular

• Calcaneocuboid joint is formed proximally Calcaneocuboid joint is formed proximally by the anterior calcaneus and distally by by the anterior calcaneus and distally by posterior cuboidposterior cuboid

Action :Action :• Transverse joint is transitional link Transverse joint is transitional link

between the hind foot and the fore foot between the hind foot and the fore foot servingserving

i.i. To add supination and pronation range to To add supination and pronation range to the TCN jointthe TCN joint

ii.ii. To compensate the fore foot and hindfoot To compensate the fore foot and hindfoot positionposition

• Compensation refers to the ability of the Compensation refers to the ability of the forefoot to remain flat on the ground forefoot to remain flat on the ground while the hindfoot is in varus or valgus while the hindfoot is in varus or valgus

Tarsometatarsal joints :Tarsometatarsal joints :• Plane synovial joints formed by cuboid and Plane synovial joints formed by cuboid and

three cuneiform bones and the bases of five three cuneiform bones and the bases of five metatarsalsmetatarsals

• Ist TMT: Base of Ist metatarsal & medial Ist TMT: Base of Ist metatarsal & medial cuneiformcuneiform

• IInd TMT : Base of IInd TMT : Base of

IInd metatarsal & IInd metatarsal &

middle cuneiform middle cuneiform

with sides of medial with sides of medial

and lateral cuneiformand lateral cuneiform

• IIIrd TMT: Base of IIIrd metatarsal & lateral IIIrd TMT: Base of IIIrd metatarsal & lateral cuneiformcuneiform

• IVth & Vth TMT : Base of IVth, Vth IVth & Vth TMT : Base of IVth, Vth metatarsal & cuboidmetatarsal & cuboid

• There are also articulations between bases of There are also articulations between bases of metatarsals so that motion at one permits metatarsals so that motion at one permits motion of anothermotion of another

Joint FunctionJoint Function::• These joints attempt to regulate the position These joints attempt to regulate the position

of the metatarsals and phalanges relative to of the metatarsals and phalanges relative to the weight-bearing surfacethe weight-bearing surface

• When the position of hindfoot is extreme When the position of hindfoot is extreme and the transverse tarsal joint is inadequate and the transverse tarsal joint is inadequate to provide compensation the TMT joints to provide compensation the TMT joints rotate to provide further adjustment of fore rotate to provide further adjustment of fore footfoot

Metatarsophalangeal JointMetatarsophalangeal Joint::• Condyloid synovial joint with 2Condyloid synovial joint with 2° freedom – ° freedom –

Flexion/Extension, Abduction/AdductionFlexion/Extension, Abduction/Adduction• ‘‘Index Minus Foot’-Index Minus Foot’- 56% people have 2 56% people have 2ndnd

metatarsal the longest followed by the 1metatarsal the longest followed by the 1stst, , through the 3through the 3rdrd to 5 to 5thth

• ‘‘Index plus minus foot’Index plus minus foot’ - 28% people have - 28% people have 11stst-2-2ndnd are of equal length are of equal length

• ‘‘Index plus foot’- Index plus foot’- 16% people have 216% people have 2ndnd metatarsal smaller than the 1metatarsal smaller than the 1stst

• The Ist MTP has two sesamoid bones which The Ist MTP has two sesamoid bones which help to increase the lever arm of FHB, help to increase the lever arm of FHB, protects the FHL against the weight bearing protects the FHL against the weight bearing traumatrauma

• The heads of the metatarsal bear weight in The heads of the metatarsal bear weight in stance phasestance phase

Joint Function:Joint Function:• The MTP joints serve primarily to allow the The MTP joints serve primarily to allow the

foot to “hinge” at the toes so that the heel foot to “hinge” at the toes so that the heel may rise off the ground while still may rise off the ground while still maintaining the small but dynamic base of maintaining the small but dynamic base of support afforded by the toes and the toe support afforded by the toes and the toe musculaturemusculature

  Metatarsal Break:Metatarsal Break: • Refers to single oblique axis that lies through the Refers to single oblique axis that lies through the

second to the fifth metatarsal headssecond to the fifth metatarsal heads• Metatarsal break may range from 54Metatarsal break may range from 54 to 73 to 73

compared to the long axis of the footcompared to the long axis of the foot• From weight bearing heel to rise there will be an From weight bearing heel to rise there will be an

active contraction of plantar flexorsactive contraction of plantar flexors• The musculature cannot normally lift the body The musculature cannot normally lift the body

weight unless the joints of the hindfoot and mid weight unless the joints of the hindfoot and mid foot are fully supinated and locked foot are fully supinated and locked

• That is the heel will rise when the foot has That is the heel will rise when the foot has become a rigid lever from the calcaneus through become a rigid lever from the calcaneus through the metatarsalsthe metatarsals

• The rigid lever will rotate around the The rigid lever will rotate around the metatarsal break –MTP axismetatarsal break –MTP axis

• LOG moves forward but lies within the LOG moves forward but lies within the BOS to maintain stabilityBOS to maintain stability

• The obliquity of the axis helps in evenly The obliquity of the axis helps in evenly distributing the weight across the toes. With distributing the weight across the toes. With a coronal axis excessive pressure would be a coronal axis excessive pressure would be laid on the 1laid on the 1stst and 2 and 2ndnd metatarsals metatarsals

• ‘‘Hallux Valgus’- Hallux Valgus’- first toe is normally first toe is normally adducted on the first metatarsal about 15adducted on the first metatarsal about 15, , an increase in this anglean increase in this angle

Inter phalengeal Joints (IP)Inter phalengeal Joints (IP)• Synovial Hinge JointsSynovial Hinge Joints• 11° of freedom – flexion/extension° of freedom – flexion/extension• Function to smooth the weight shift to the Function to smooth the weight shift to the

opposite foot in gait and help maintain the opposite foot in gait and help maintain the stability by pressing against the ground both stability by pressing against the ground both in static posture and in gaitin static posture and in gait

Plantar ArchesPlantar Arches::• The bony and ligamentous configuration of the The bony and ligamentous configuration of the

TCN joint, the transverse tarsal joint, and the TCN joint, the transverse tarsal joint, and the TMT joints combine to produce a structural vault TMT joints combine to produce a structural vault with in the footwith in the foot

• Shape and arrangement of bones are particularly Shape and arrangement of bones are particularly responsible for stability of plantar archesresponsible for stability of plantar arches

• 2 different arches2 different arches1.1. Longitutional arch:Longitutional arch:• Based posteriorly at the calcaneum and anteriorly Based posteriorly at the calcaneum and anteriorly

at the metatarsal headsat the metatarsal heads• Medial and lateralMedial and lateral• The medial side is the side for referenceThe medial side is the side for reference

2.2. Transverse arch:Transverse arch:• Visualized at the level of the anterior Visualized at the level of the anterior

tarsals and at the bases of metatarsalstarsals and at the bases of metatarsals• Middle cuneiform is the keystone of the Middle cuneiform is the keystone of the

archarch

  Function:Function:• The arches are adapted exclusively to serve weight The arches are adapted exclusively to serve weight

bearing functions of the footbearing functions of the foot

Stability functions:Stability functions:• The following stability functions could be The following stability functions could be

performed by a foot with a fixed arch structure. performed by a foot with a fixed arch structure.

a.a. Distribution of weight through the foot for proper Distribution of weight through the foot for proper weight bearingweight bearing

b.b. Conversion of foot to a rigid leverConversion of foot to a rigid lever• Distribution of body weight depends on the shape Distribution of body weight depends on the shape

of the arch and location of LOGof the arch and location of LOG• It begins at the talusIt begins at the talus

• In bilateral stance the talus receives 50% of body In bilateral stance the talus receives 50% of body weight and in unilateral stance it is 100%weight and in unilateral stance it is 100%

• 50% of the weight received by the talus is divided 50% of the weight received by the talus is divided into subtalar and TCN and calcaneocuboid into subtalar and TCN and calcaneocuboid articulationsarticulations

• Because of the medial location of the talus the Because of the medial location of the talus the medial side bears more weight than the lateralmedial side bears more weight than the lateral

• Similarly in bilateral stance distribution of weight Similarly in bilateral stance distribution of weight across the MT heads occurs in a 2:1:1:1:1 ratio across the MT heads occurs in a 2:1:1:1:1 ratio from 1from 1stst-5-5thth ray ray

Mobility functions:Mobility functions:a.a. Dampening the shock of weight bearingDampening the shock of weight bearingb.b. Adapting to changes in supporting surfaceAdapting to changes in supporting surfacec.c. Dampening super imposed rotationsDampening super imposed rotations

• Pes Planus – flat foot Pes Planus – flat foot • Pes cavus – high archPes cavus – high arch