Chapter 19

1. Chapter 19 The Leg, Foot and Ankle

2. Overview • The ankle and foot is a complex structure comprised of 28 bones (including 2 sesamoid bones) and 55 articulations (including 30 synovial joints), interconnected by ligaments and muscles • In addition to sustaining substantial forces, the foot and ankle serve to convert the rotational movements that occur with weight bearing activities into sagittal, frontal, and transverse movements

3. Anatomy • Anatomically and biomechanically, the foot is often subdivided into: • The rearfoot or hindfoot (the talus and calcaneus) • The midfoot (the navicular, cuboid and the 3 cuneiforms) • The forefoot (the 14 bones of the toes, the 5 metatarsals, and the medial and lateral sesamoids)

4. Anatomy • Distal Tibiofibular Joint • Classified as a syndesmosis • Consists of a concave tibial surface and a convex or plane surface on the medial distal end of the fibula

5. Anatomy • The talocrural (ankle) joint • Formed between the saddle-shaped talus and the distal tibia • Classified as a synovial hinge or a modified sellar joint

6. Anatomy • Subtalar (talocalcaneal) joint • The subtalar joint is a synovial, bicondylar compound joint consisting of two separate, modified ovoid surfaces with their own joint cavities (one male and one female) • This relationship ensures that the anterior and posterior aspects can move in opposite directions to each other during functional movements (while the anterior aspect is moving medially, the posterior aspect is moving laterally)

7. Anatomy • Talocalcaneal joint ligaments • A number of ligaments provide support to this joint, although some confusion exist in the descriptions and nomenclature of these ligaments • The two superficial ligaments are the lateral and posterior talocalcaneal ligaments • The deep ligaments include the interosseous, cervical, and axial ligaments, often referred together as the interosseous ligaments

8. Anatomy • The midtarsal joint complex • Consists of the talonavicular and calcaneocuboid articulations • The talonavicular joint is classified as a synovial, compound, modified ovoid joint • Formed by components of the talus, navicular, calcaneus and plantar calcaneonavicular (spring) ligament • The calcaneocuboid joint is classified as a simple, synovial modified sellar joint

9. Anatomy • Ligaments of the mid-tarsal joints • A number of ligaments help provide support to this region: • The spring ligament (plantar calcaneonavicular) connects the navicular bone to the sustentaculum tali on the calcaneus • The ligaments of the calcaneocuboid joint include the long plantar ligament and a portion of the bifurcate ligament dorsally

10. Anatomy • The cuneonavicular joint • Classified as a compound, synovial, modified ovoid joint

11. Anatomy • Intercuneiform and Cuneocuboid Joints • These joints are classified as compound, synovial, modified ovoid joints

12. Anatomy • Cubometatarsal joint • When considered alone, this joint is classified as a compound modified ovoid, synovial joint

13. Anatomy • The cubonavicular joint • Classified as a syndesmosis, or a plane surfaced joint

14. Anatomy • Intermetatarsal joints • The first intermetatarsal joint is classified as a simple, synovial, modified ovoid joint, while the 2nd, 3rd and 4th are classified as compound joints

15. Anatomy • The metatarsophalangeal (MTP) joints • Classified as simple, synovial, modified ovoid joints

16. Anatomy • The interphalangeal (IP) joints • Classified as simple, synovial modified sellar joints

17. Anatomy • Plantar fascia/aponeurosis • The plantar fascia is the investing fascial layer of the plantar aspect of the foot that originates from the os calcis and inserts through a complex network to the plantar forefoot • A tough, fibrous layer, composed histologically of both collagen and elastic fibers • Three portions

18. Anatomy • Plantar fascia/aponeurosis • With standing and weightbearing, the plantar fascia plays a major role in the support of the weight of the body by virtue of its attachments across the longitudinal arch.

19. Anatomy • Retinacula • There are four important ankle retinacula, which function to tether the leg tendons as they cross the ankle to enter the foot

20. Anatomy • The extrinsic muscles of the foot • Can be divided into anterior, posterior superficial, posterior deep, and lateral compartments

21. Anatomy • The extrinsic muscles of the foot • Anterior compartment • This compartment contains the dorsiflexors (extensors) of the foot. These include the tibialis anterior, extensor digitorum longus, extensor hallucis longus, and peroneus tertius • Posterior superficial compartment • This compartment, located posterior to the interosseous membrane, contains the calf muscles which plantarflex (flex) the foot. These include the gastrocnemius, soleus, and the plantaris muscle

22. Anatomy • The extrinsic muscles of the foot • Posterior deep compartment • This compartment contains the flexors of the foot. These muscles include the posterior tibialis, flexor digitorum longus, and flexor hallucis longus • Lateral compartment • This compartment contains the peroneus longus and brevis

23. Anatomy • The intrinsic muscles of the foot • Subdivided into 4 layers • 1st layer: • Abductor hallucis • Abductor digiti minimis • Flexor digitorum brevis • 2nd layer • Flexor digitorum accessorius (quadratus plantae) • Lumbricales

24. Anatomy • The intrinsic muscles of the foot • 3rd layer • Flexor hallucis brevis • Flexor digiti minimis • Adductor hallucis • 4th layer • Dorsal interossei • Plantar interossei

25. Anatomy • The dorsal intrinsic muscles of the foot • Consist of the extensor hallucis brevis (EHB) and extensor digitorum brevis (EDB) muscles

26. Anatomy • Arches of the foot • There are 3 main arches: • The medial longitudinal • The lateral longitudinal • The transverse

27. Anatomy • Neurology • The saphenous nerve, the largest cutaneous branch of the femoral nerve, provides cutaneous distribution to the medial aspect of the foot • The sciatic nerve provides the sensory and motor innervation for the foot and leg • It divides into the common peroneal and tibial nerves. The common peroneal nerve in turn divides into the superficial peroneal, deep peroneal nerves. The tibial nerve divides into the sural, medial calcaneal, medial plantar, and lateral plantar nerves

28. Anatomy • Vascular supply • Two branches of the popliteal artery, the anterior tibial artery and the posterior tibial artery, form the main blood supply to the foot

29. Biomechanics • Terminology • Motions of the leg foot and ankle consist of single plane and multi-plane movements. The single plane motions include: • The frontal plane motions of inversion and eversion • The sagittal plane motions of dorsiflexion and plantarflexion • The horizontal plane motions of adduction and abduction

30. Biomechanics • A triplane motion describes a movement about an obliquely oriented axis through all three body planes. • Triplanar motions occur at the talocrural, subtalar, and midtarsal, joints, and at the first and fifth rays. • Pronation and supination are considered triplanar motions

31. Biomechanics • Pronation • The three body plane motions in pronation are abduction in the transverse plane, dorsiflexion in the sagittal plane, and eversion in the frontal plane

32. Biomechanics • Supination • The three body plane motions in supination are a combined movement of adduction, plantarflexion, and inversion

33. Biomechanics • Proximal tibiofibular joint • Because of the interaction between the proximal and distal tibiofibular joints with the knee and the ankle function, the clinician should always evaluate the functional mobility of both these complexes when treating one or the other

34. Biomechanics • Talocrural Joint • The primary motions at this joint are dorsiflexion and plantar flexion, with a total range of 70-80° • Theoretically, the capsular pattern of the ankle joint is more restriction of plantarflexion than dorsiflexion, although clinically this appears to be reversed • The close-packed position is weight-bearing dorsiflexion, while the open-packed position is midway between supination and pronation.

35. Biomechanics • The subtalar joint • Subtalar joint supination and pronation are measured clinically by the amount of calcaneal or hindfoot inversion and eversion • In normal individuals, there is an inversion to eversion ratio of 2:3 to 1:3, which amounts to approximately 20° of inversion and 10° of eversion

36. Biomechanics • Subtalar joint • The capsular pattern of this joint varies. In chronic arthritic conditions, there is an increasing limitation of inversion, but with traumatic arthritis, eversion appears most limited clinically • The close-packed position for this joint is full inversion, while the open-packed position is inversion/plantarflexion

37. Biomechanics • The midtarsal joint complex • Provides the foot with an additional mechanism for raising and lowering the arch, and to absorb some of the horizontal plane tibial motion that is transmitted to the foot during stance • The talonavicular joint two degrees of freedom: plantar flexion/dorsiflexion and inversion/eversion, with motion occurring around a longitudinal and oblique axis, both of which are independent of each other • The capsular pattern is a limitation of dorsiflexion, plantar flexion, adduction and internal rotation • The close packed position is pronation • The open packed position is midway between extremes of range of motion

38. Biomechanics • The midtarsal joint complex • The capsular pattern for the calcaneocuboid joint is a limitation of dorsiflexion, plantar flexion, adduction and internal rotation

39. Biomechanics • The cuneonavicular joint • Has one to two degrees of freedom: plantar/dorsiflexion, inversion/eversion • The capsular pattern is a limitation of dorsiflexion, plantar flexion, adduction and internal rotation • The close-packed position is supination • The open-packed position is considered to be midway between the extremes of range of motion

40. Biomechanics • Intercuneiform and Cuneocuboid Joints • Due to their very plane curvature, these joints have only one degree of freedom: inversion/eversion • The close packed position for these joints is supination • The open packed position is considered to be midway between extremes of range of motion

41. Biomechanics • Cubometatarsal Joint • The capsular pattern of this joint is a limitation of dorsiflexion, plantar flexion, adduction and internal rotation • The close-packed position is pronation. • The open-packed position is considered to be midway between extremes of range of motion

42. Biomechanics • Cubonavicular Joint • The close-packed position for this joint is supination • The open-packed position is midway between extremes of range of motion

43. Biomechanics • Intermetatarsal Joints • The close-packed position for these joints is supination • The open-packed position is midway between extremes of range of motion

44. Biomechanics • Metatarsophalangeal Joints • The MTP joints have two degrees of freedom: flexion/extension and abduction/adduction. • Range of motion of these joint is variable, ranging from 40° to 100° dorsiflexion (with a mean of 84°), 3° to 43° (mean, 23°) plantar flexion, and 5° to 20° varus and valgus • The closed-packed position for the MTP joints is full extension • The capsular pattern for these joints is variable, with more limitation of extension than flexion • The open-packed position is 10º of extension.

45. Biomechanics • 1st Metatarsophalangeal Joint • The function of the great toe is to provide stability to the medial aspect of the foot, and to provide for normal propulsion during gait. Normal alignment of the 1st MTP joint varies between 5° varus and 15° valgus • The great toe is characterized by having a remarkable discrepancy between active and passive motion. Approximately 30° of active plantar flexion is present, and at least 50° of active extension, which can be frequently increased passively to between 70-90°.

46. Biomechanics • Interphalangeal (IP) Joints • Each of the IP joints has one degree of freedom: flexion/extension • The capsular pattern is more limitation of flexion than of extension • The close-packed position is full extension • The open-packed position is slight flexion

47. Examination • The examination is used to identify static and dynamic, structural or mechanical foot abnormalities • The clinical diagnosis is based on an assessment of the changes in joint mobility and tissue changes at the foot and ankle, and the effect these have on the function of the remainder of the lower kinetic chain

48. Examination • History • The primary purposes of the history are to: • Determine the severity of the condition • Determine the area, nature and behavior of the symptoms • Help determine the specific structure at fault • Detect systemic conditions (collagen disease, neuropathy, radiculopathy, and vascular problems), or the presence of serious pathology

49. Examination • Systems Review • As symptoms can be referred distally to the leg, foot and ankle from a host of other joints and conditions, the clinician must be able to differentially diagnose from the presenting signs and symptoms • The cause of the referred symptoms may be neurological or systemic in origin. If a disorder involving a specific nerve root (L 4, L 5, S1, or S 2) is suspected, the necessary sensory, motor and reflex testing should be performed • Peripheral nerve entrapments, although not common, may also occur in this region and often go unrecognized

50. Examination • Systems Review • Systemic problems that may involve the leg, foot and ankle include diabetes mellitus (peripheral neuropathy), osteomyelitis, gout and pseudogout, sickle cell disease, complex regional pain syndrome, peripheral vascular disease, and rheumatoid arthritis