Calcaneus and STJ PDF

Calcaneus and STJ Calcaneus Bones of the Foot • Hindfoot (rearfoot) • Talus • Calcaneus • Form the functional subtalar joint (STJ) • Midfoot • 5 tarsal bones • Sometimes referred to as the lesser tarsus • Separated from the rearfoot by the midtarsal joint (MTJ) • Functional joint • Forefoot...

Calcaneus and STJ Calcaneus Bones of the Foot • Hindfoot (rearfoot) • Talus • Calcaneus • Form the functional subtalar joint (STJ) • Midfoot • 5 tarsal bones • Sometimes referred to as the lesser tarsus • Separated from the rearfoot by the midtarsal joint (MTJ) • Functional joint • Forefoot • Metatarsals • Phalanges Tarsals of the Rearfoot • Talus • Articulates with the navicular, calcaneus (red arrows) and the spring ligament (not shown) • Calcaneus (os calcis) • Largest, most plantar tarsal bone • Articulates with the cuboid (blue arrow) and the talus • Rectangular in shape • Six surfaces • Talus and calcaneus are part of both the STJ and MTJ** Dorsal Surface of the Calcaneus • Anterior third • Anterior facet for articulation with the talus • Middle facet for articulation with the talus • Lies on the sustentaculm tali • Most medial A • Sulcus calcanei A M SC M P • Rough area posterolateral to facets • Attachment of ligaments, one muscle • Wider laterally just like the sulcus tali • Middle third P Posterior surface • Posterior facet for articulation with the talus • Large, oval-shaped • Convex anterior to posterior • Posterior third • Rough and concave • Pre-Achilles fat pad • Sits in the concavity and separates the Achilles tendon from the ankle joint Left and right calcanei Lateral Surface of the Calcaneus • Relatively flat and subcutaneous • Rough surface • Peroneal tubercle (trochlea) CFL • Attachment of a retinaculum • Separates the two peroneal tendons (lateral compartment of the leg) • Attachment of the calcaneofibular ligament (CFL) • Superior and 1 cm posterior to the tubercle • May be marked by a smaller tubercle Medial Surface of the Calcaneus • Quite concave from anterior to posterior • Slightly concave superior to inferior • Sustentaculum tali • Large shelf-like boney projection • Has its own 6 surfaces: • Dorsal • Contains middle facet for talus • Plantar: P M A • Groove for flexor hallucis longus tendon • Medial: • Rough superior area for attachment of calcaneotibial ligament of deltoid • Groove for another flexor tendon • Posterior: • Medial talocalcaneal ligament • Anterior: • Plantar calcaneonavicular ligament (spring ligament) Plantar Surface of the Calcaneus • Calcaneal tuberosity • Rough area located posteriorly • Major WB area of the calcaneus SL SL • Divided into: ATSPL • Large medial process • Smaller lateral process • Attachment site for muscles and ligaments • Long plantar ligament • One of the strongest ligaments of the foot • Attaches just distal to the two processes • Distal to tuberosity LPL MP LPL • Triangular rough area with longitudinal striae LP • Anterior tubercle • Attachment site for the short plantar ligament • Transverse groove distal to the tubercle • Part of spring ligament attachment • Attachment of capsule of calcaneocuboid joint Distal (Anterior) Surface of the Calcaneus Plantar calcaneus: • Smallest of all the surfaces CF Anterolateral cuboid: (facet is concave side to side) dorsal Facet for calcaneus • Dorsal aspect extends more distal • Plantar aspect is more proximal • Completely covered with articular cartilage • Facet for the cuboid • Convex side to side • Concave superior to inferior • Articulates with the cuboid • Saddle synovial joint Posterior Surface of the Calcaneus Middle facet Posterior facet Divided into 3 areas by 2 horizontal grooves: • (1) superior area • Smooth area where deep retrocalcaneal bursa lies Sustentaculum tali Groove for flexor hallucis longus (FHL) • (2) middle third • Largest of the 3; rough • Attachment site of the Achilles tendon 1 2 3 Calcaneal tuberosity Medial and lateral processes Peroneal tubercle • (3) inferior area • Slopes inferiorly and anteriorly • Forms part of the WB area of the heel • Covered with the heel fat pad Lateral X-ray of the Ankle • Bohler’s angle • Basically measures the height of the posterior facet of the calcaneus Anterior superior process of the calcaneus • Between Line 1 and Line 2 2 1 • Line 1: Drawn from the most superior aspect of the posterior facet to the most posterior aspect of the posterior surface • Line 2: Drawn from the most superior aspect of the posterior facet to the most superior aspect of the anterior calcaneus • Anterior (superior) process of the calcaneus • Radiographic term Neutral Triangle of the Calcaneus • Area of sparse trabeculation (less bone) inferior to the anterior edge of the posterior facet • Between the red arrows • Weak point in the calcaneus • In a fall from a height • Lateral process of the talus gets forced inferiorly into the calcaneus • Fracture of calcaneus Calcaneal Fractures • Normal Bohler’s Angle on the top Xray. • Decrease in the Bohler’s Angle lower Xray seen during calcaneal fractures. Types of Calcaneal Fractures • Intra-articular Fractures Most serious type of fractures Usually will develop into post traumatic arthritis • Avulsion Fractures Often pulled from the Achilles tendon or ligament • Multiple Fracture Fragments Crush type injury most common fall from height • Stress Fractures Overuse and repetitive trauma Calcaneal Fractures Calcaneal Fractures Classification Type 1 - all types of intra-articular fractures with < 2mm displacement regardless of the number of fracture lines/fragments. Type 2A -one primary fracture line through the lateral aspect of the posterior facet. Type 2B -one primary fracture line through the central aspect of the posterior facet. Type 2C -one primary fracture line through the medial aspect of the posterior facet and a transverse fracture through the body. Calcaneal Fractures Classification Type 3AB -involves 2 primary fracture lines - lateral aspect of the posterior facet - central aspect Type 3AC -involves 2 primary fracture lines -lateral aspect of the posterior facet -medial aspect of the posterior facet Type 3BC -involves 2 primary fracture lines - central aspect of the posterior facet - medial aspect of the posterior facet Type 4 -involves 3 or more primary fracture lines with >2mm articular displacement (severe comminuted fractures) Normal Lateral X-ray • Radiolucent areas (cartilage) 1 talus 2 5 3 8 9 4 calcaneus cuboid 7 6 6 Nav. • • • • • 1. ankle joint 2. posterior facet 3. middle facet 4. calcaneocuboid joint 5. talonavicular joint • Radiopaque areas (bone) • 6. calcaneal tuberosity • 7. anterior tubercle of the calcaneus • 8. anterior superior process of the talus • 9. sustentaculum tali Ossification of the Calcaneus • Only tarsal bone to always ossify from a 1o center and a 2o center • 1o center appears at 3 months I.U • 2o center of ossification appears in the calcaneal tuberosity 6-8 years of age • Calcaneal apophysis • Appears as a scale-like area on the posteroinferior aspect of the calcaneus • Appears earlier in females • Fuses with 1o center 14-16 years of age T Ca Sinus Tarsi • Tunnel between the sulcus calcanei and the sulcus tali • Non-articular space between the talus and the calcaneus • Anterolateral to posteromedial tibia fibula talus Calc. Sinus Tarsi Articular areas, synovial joints Non-articular area between the talus and the calcaneus Pes Planus • Flatfoot • Longitudinal arch of the foot is flattened • Common foot deformity • Don’t see the sinus tarsi on X-ray • Calcaneal spur • Heel spur • Boney outgrowth from the calcaneal tuberosity • Medial process • Plantar fascia attaches • Plantar fasciitis WB Lateral X-ray of the Foot Posterior Talocalcaneal Joint • Articulation between the posterior facets of the talus and the calcaneus • Planar, gliding synovial joint • Does not communicate with any other joint • Separated from the anterior and posterior facets by the sinus tarsi • Called the anatomical subtalar joint Ligaments of the posterior TC joint Ligaments of the Posterior Talocalcaneal Joint • Medial talocalcaneal Medial malleolus • Connects medial tubercle of the talus to the posterior surface of the sustentaculum tali • Blends with the deltoid and interosseous ligaments Deltoid L. • Posterior talocalcaneal • Connects the lateral and medial tubercles of the talus to the dorsal calcaneus • May be a single band or Yshaped Medial talocalcaneal ligament N ST Short plantar ligament Spring ligament Long plantar ligament Posterior talocalcaneal ligament Ligaments of the Posterior Talocalcaneal Joint • Lateral talocalcaneal (4) • Connects lateral process of talus to calcaneus • Deep to CFL of ankle joint • Interosseous talocalcaneal ligament (5) • Lateral to the sinus tarsi • Connects dorsal calcaneus to the neck (cervix) of the talus lig . • Cervical ligament (6) ATF lig. CF • Broad flattened ligament within the sinus tarsi • Passes obliquely from sulcus calcanei to sulcus tali Talocalcaneonavicular Joint Sinus tarsi medially is very small. (Sometimes referred to as the tarsal canal) • Several articular surfaces within one joint capsule • One joint cavity • Multiaxial synovial joint • Difficult to classify • Includes: • Talocalcaneal part anatomic (posterior talocalcaneal joint) • Anterior and middle facets of the talus and calcaneus • Talonavicular part • Talar head articulating with the posterior surface of the navicular • Talar head articulating with fibrocartilage in the spring ligament Talocalcaneonavicular Joint • Joint capsule is weak and irregular • Reinforced by ligaments: • Posterior capsule is thickened by the interosseous talocalcaneal ligament • Plantar calcaneonavicular ligament • Spring ligament • Dorsal talonavicular ligament • Bifurcate ligament Spring ligament Bifurcate ligament Bifurcate Ligament • Stem attaches to the dorsal calcaneus, lateral to the cervical ligament • Area of the anterior superior process of the calcaneus • Splits in two and attaches to: • Dorsal lateral navicular • Stabilizes the talocalcaneonavicular joint • Dorsal medial cuboid • Stabilizes the calcaneocuboid joint • Not part of TNC joint Dorsal talonavicular ligament Bifurcate Ligament • Excessive traction of the bifurcate ligament as in an inversion injury • May cause an avulsion fracture of the anterior (superior) process of the calcaneus • Often missed on X-ray Spring Ligament • Most important ligament of the TCN joint • Very strong, broad ligament • Helps to support the head of the talus • Helps to maintain medial longitudinal arch of the foot • Attachments: • Anterior surface of the sustentaculum tali of the calcaneus • Plantar aspect of navicular • Deep to the short plantar ligament Spring lig. Spring Ligament Talus removed: • Fibrocartilaginous thickening within the spring ligament • Articulates with the beveled triangular area of the talar head • Spring ligaments blends with the deltoid and other ligaments in the region Superior Inferior Spring ligament Fibrocartilage Spring ligament may have superior and inferior bands that are separated by fatty tissue. Functional Subtalar Joint Spring ligament • Functional joint Talonavicular joint Bifurcate ligament • Clinical joint • Combination of anatomical joints • Important to know the difference • i.e. injection of a joint • Functional subtalar joint is 1 ½ anatomical joints • 3 articular facets of the talus and calcaneus • Abbreviated STJ Cervical ligament Interosseous TC lig. Cervical ligament Posterior articular facets Right foot, talus reflected medially Subtalar Joint (STJ) • STJ movement and axis of rotation are complex • More detail in Biomechanics course • Triplane joint with a triplane axis • Axis is oblique • Average is 42o from transverse plane 16o medial to the sagittal plane • Movement occurs in all 3 planes at the same time • Pronation and supination • Motion that is easiest to measure • Inversion/eversion • Twice as much inversion as eversion • normally eversion inversion Planes & Movements of the Foot • Frontal/coronal plane • Inversion and eversion • Sagittal plane • Dorsiflexion and plantarflexion • Transverse plane • Abduction and adduction Planes & Movements of the Foot • Sagittal plane • Dorsiflexion • Dorsum (superior aspect) of the foot moves closer to the leg Dorsum • Plantarflexion • Plantar foot (sole) moves further from the leg • Extends the foot Plantar • Coronal plane • Inversion • Plantar (sole) foot turns medially Dorsum Plantar • Eversion • Plantar (sole) foot turns laterally Pronation and Supination PRONATION = eversion, dorsiflexion and abduction SUPINATION = inversion, plantar flexion and adduction