Foot and ankle anatomy & biomechanics.pptx

F&A

1. FOOT AND ANKLE: Anatomy and Biomechanics Presenter: NTAMBARA K. Nelson MD,PGY4 Supervisor: Dr Olivier KUBWIMANA, orthopedic surgeon at CHUB

2. Learning objectives To understand the complex anatomy of the foot and ankle To know important blood supply of the foot To understand the biomechanics of the foot and ankle to know the role of the foot and ankle in gait cycles

3. Introduction The ankle joint is made up of the tibia, fibula, and talus. Its primary motion is dorsiflexion and plantar flexion. Foot and ankle have a dense concentration of structures on small area Foot is flexible with many joints to allow moving on uneven ground Foot also is rigid to provide lever arm for gait cycle

4. Bone and ligaments: The ankle joint The ankle joint is a hinge joint; formed by the tibia, talus, and fibula. The talar dome is biconcave with a central talar sulcus. The radius of curvature is greater laterally. Viewed axially, the joint is trapezoidal and wider anteriorly. The talus is the only tarsal bone without muscular or ligamentous insertions.

5. Bones of the foot 7 Tarsals 5 Metatarsals 14 Phalanges Divided Fore foot Mid-foot Hind foot

6. Arches of the foot Medial longitudinal arch Lateral longitudinal arch Transverse arch

7. Vascular supply 3 major artery supply ankle and foot: Anterior tibial artery Posterior tibial artery Peroneal artery Plantar arcades: Medial plantar artery Lateral plantar artery

8. Osseous vascular supply of interest 1. TALUS 5 bony region:( the tarsal canal, the sinus tarsi, the superior neck, the medial body, and the posterior tubercle) The talar neck is well vascularized by anastomotic ring The talar body receives most of its blood supply retrograde through the artery of the tarsal canal

9. Talus blood supply Primary blood supply to the talar body is from the artery of the tarsal canal (posterior tibial artery) Other blood supply is from the superior neck vessels (anterior tibial artery) and the artery of the tarsal sinus ( dorsalis pedis ).

10. 2.Navicular The periphery is well vascularized, but the central third is less vascular. The navicular is prone to stress fracture in the dorsal third, where the compressive forces are concentrated. 3 . Fifth metatarsal The proximal blood supply to the fifth metatarsal is through the tuberosity, creating a watershed area at the proximal metaphyseal / diaphyseal junction, which is prone to stress fractures and nonunion.

11. Nerve of the foot and ankle

12. Ankle stability Lateral ankle ligamentous complex:inversion /tibia ext rot Anterior talofibular ligament (ATFL) Calcaneofibular ligament (CFL) Posterior talofibular ligament (PTFL) Deltoid ligament:eversion Triangle shaped ligament Deep and superficial components Syndesmosis: 3 lgt Anterior inferior tibiofibular ligament (AITFL)35% Interosseous ligament 22% Posterior talofibular ligament 43%.

13. Bone and ligaments: Hind-foot/Mid-foot Subtalar joint: 3 facets: Anterior: talonavicular joint middle: medial Posterior: largest Pronation/supination Naviculocuneiform and intercuneiform Dense ligamentous structures Transverse tarsal joint/chopart Talonavicular joint (spring lgt complex) Superior medial calcaneonavicular lgt Inferior calcaneonavicular lgt Calcaneocuboid joint: Saddle shapped

14. Tarsometatarsal joint Metatarsocuneiform joints 1,2,3 Metatarsocuboid joints 4 &5 Roman arch in axial plane 2 nd metatarsal base keystone Ligamentous support: 3layers Interosseous layers; lisfranc lgt: strongest Plantar layer :next strong Dorsal layer:weaker

15. Bone and ligament:Forefoot The first metatarsophalangeal (MTP) joint Interphalangeal joints 1,2,3,4,5 formed plantarly by the dense phalangeosesamoidal complex, or plantar plate The plantar fascia originates from the medial calcaneal tuberosity and inserts distally on the base of the fifth metatarsal (lateral band), as well as the plantar plate and bases of the five proximal phalanges.

16. Windlass mechanism

17. Muscles and tendons 1. Muscle compartment of the leg

18. Muscles of plantar aspect of the foot

19. 3.Muscles of the dorsal foot

20. Biomechanics Ankle joint: Ankle joint is uniplanar hinge joint Its motion is in transverse axis joining malleoli The axis is oblique by 10° This leads to dorsiflexion/medial and plantar flexion/lateral Privide 11°of tibial rotation Subtalar joint increase the rotation up to 19° Large load bearing surface 11-13cm 1mm talar shift is 42%less contact Tibiofibular joint Motion limited to 2mm due to tight syndesmosis Low contact stress,less osteoarthritis

21. Ankle & foot & Gait At initial contact (heel strike in normal gait), the ankle is in neutral to slight plantar-flexion. The ground reaction causes immediate plantar flexion At mid stance there is dorsiflexion The motion then returns to plantar-flexion with heel-rise during the late stance phase At lift-off at the beginning of the swing phase, the ankle is in plantar-flexion. The motion reverses towards dorsiflexion in the middle of the swing phase

22. Soft tissue contribution to gait mechanics Swing phase Anterior tibialis contracts concentrically Loss of function lead to foot drop/steppage gait Heel strike Anterior tibialis contracts eccentrically Controls the rate of foot strike the ground Foot drop result in loud slap Foot flat Gastrocnemius soleus complex eccentric contraction Toe off Gastrocnemius soleus complex concentric contraction

23. Take home message Ankle and foot have complex anatomy Understanding muscle balance around the uncle helps in management of congenital foot deformity. Main functions are to support the body during stance, acts as lever arm for propulsion during gait and for shock absorption.

24. References AAOS COMPREHENSIVE ORTHOPAEDIC REVIEW,volume1,pg1150 Miller’s review of orthopedics 7 th edition,pg487 Edward J C Dawe James Davis, Anatomy and biomechanics of the foot and ankle, mini-symposium: the foot and ankle Robert Donatella, ma, normal biomechanics of the foot and ankle the journal of orthopedic and sports physical therapy copyright 0 1985 by the orthopedic and sports physical therapy sections of the American physical therapy association.