C lin ic a l

P e r spe c t iv e

F o o t a n d A n k l e B iomechanics

ABSTRACT: and injuries are common in sportsmen and the general population. The impact that the functional anatomy and bio­ HUNTER L J, BSc PHYSIOTHERAPY mechanics of the foot and ankle complex has on normal is reviewed. FORTUNE J, BSc PHYSIOTHERAPY2 The abnormal biomechanics associated with overpronation and over­ Physiotherapy Department, University of the Witwatersrand supination are discussed, as are their consequences. The management Physiotherapy Department University of the Witwatersrand principles of foot and ankle injuries are briefly described.

KEYWORDS: FOOT AND ANKLE BIOMECHANICS, OVERPRONATION AND OVERSUPINATION

INTRODUCTION FIGURE 1. The joints of the ankle and foot contribute to the combination of Foot and ankle injuries are extremely movements that occur during gait. (Adapted from "Reid D 1992 Sports injury common, both in sportsmen and in assessment and rehabilitation. New York: Churchill Livingstone.) the general population (Rundle, 1995). Fifty-three percent of all basketball injuries, and 31% of soccer injuries involve the foot and ankle (Garrick, 1977). Ankle sprains account for the most time lost by athletes due to injury (Reid, 1992). The estimated incidence of ankle sprains is 1:10 000 people per day in the United States (McCulloch, et al, 1985). )

. The predisposition to injury of the 3

1 foot and ankle complex can only be 0

2 understood by studying the anatomy and d

e biomechanics of this region. t a d (

THE ANATOMY (See Figure 1.) r e h s i

l 1. Talocrural Joint b

u The ankle is a uniaxial hinge joint. The P medial and lateral malleoli (mortice) and e h

t the talus, also known as the talocrural

y joint, have an inherent bony stability. b

d The position and orientation of the e t ligaments (predominantly the lateral li­ n a gament complex, the deltoid or medial r g ligament and ligaments of the syndes­ e c

n mosis) further enhance this passive sta­ M idfoot ______I I______Forefoot ______I e c bility. The muscles crossing the ankle i l

r (flexor hallucis brevis; flexor digitorum; e d gastrocnemius; soleus; peroneus longus; complex, and Boruta et al (1990), n u brevis and tertius; extensor digitorum include the lateral talocalcaneal liga­ CORRESPONDENCE: y longus and extensor digitorum brevis) ment as a fourth component of the com­ a L J Hunter w provide active stability. plex, but most authors are in agreement Physiotherapy Department e t a Figure 2.1 show the lateral ligament about the ligaments named above. University of the Witwatersrand G complex consisting of the anterior talo­ The ATL is long and thin and may be t 7 York Road e

n fibular ligament (ATL), the calcaneo- considered a thickening of the anterior Parktown i b fibular ligament (CFL) and the posterior joint capsule. Because of its orienta­ 2193 a S

talofibular ligament (PTL). Renstrom tion, its main function is to limit inver­ Tel: (O il) 488-3450/2 (w) y b and Konradsen (1997) include the sub­ sion while the foot is plantar flexed (011)465-4615 (h) d

e talar ligaments in the lateral ligament (Rasmussen, 1985). The ATL is relaxed Fax: (011)488-3210 c u d o SA Jo u r n a l o f Physiotherapy 2000 V o l 56 No 1 17 r p e R FIGURE 2.1. The lateral ligament complex consisting of the anterior talofibular Figure 2.2 shows the medial or deltoid ligament, the calcaneofibular ligament and the posterior talofibular ligament. ligament. The deltoid ligament is strong (Adapted from "Reid D 1992 Sports injury assessment and rehabilitation. and therefore much less likely to be New York: Churchill Livingstone.) injured. It limits eversion of the ankle. If the deltoid ligament is damaged, an associated fracture of the lateral mal­ leolus or a tearing of the tibiofibular 1 syndesmosis must be excluded. The hinge joint allows dorsi and plan­ tar flexion with some accessory gliding. Dorsi and plantar flexion movement does not occur in one plane, but three (the triplanar movement of the ankle). This is due to the asymmetrical shape of the body of the talus, and the obliquity of the ankle joint axis (approximately 40° anterior of the frontal plane on the medial side of the ankle) (Norkin and Levangie, 1992). The ‘components’ of dorsi and plantar flexion will vary, depending on whether the movement is performed in an open chain or a closed chain. In an open chain movement, i.e. the foot is free and non­ FIGURE 2.2. The medial or deltoid ligament complex consisting of the posteri­ weight bearing, dorsi-flexion involves or tibiotalar fibres, tibiocalcaneal fibres, and tibio-navicular fibres. The plantar abduction and eversion, and plantar calcaneo-navicular ligament is depicted. (Adapted from "Reid D 1992 Sports flexion includes adduction and inver­ )

. injury assessment and rehabilitation. New York: Churchill Livingstone.) sion. However, during a closed chain 3

1 movement, i.e. weight bearing position, 0 2

dorsiflexion includes adduction and d

e inversion, and plantar flexion involves t a abduction and eversion. Patients with d ( foot and ankle problems must therefore r e be assessed in weight-bearing and non­ h s i l weight bearing positions e.g. lying and b

u standing (Donatelli, 1996). P The most stable position of the ankle e h

t is in dorsiflexion as the talus ‘locks’

y into the ankle mortice (the close-pack b

d position). Conversely plantar flexion is e t the most unstable position. n a r g 2. Subtalar Joint e c

n This is the articulation between the cal­ e c caneus and the talus, i.e. the rearfoot. i l

r Supination and pronation occur at the e d subtalar joint, in combination with n u accessory movements. Abduction and y

a in the neutral position of the foot. The 1997), but it may be taut in dorsiflexion dorsiflexion occur with pronation, and w

e CFL is relaxed in normal standing and (Renstrom and Konradsen, 1997) or in adduction and plantar flexion with t a does not have a major role in talotibial eversion and plantar flexion (Rundle, supination. This movement of the sub­ G

t joint stability. It appears to limit exces­ 1995). Donatelli (1996) claims the PTL talar joint alters the rearfoot and forefoot e

n sive dorsiflexion and acts as a guide is the prime stabiliser during plantar angles (Heil, 1992), and allows the foot i b for the axis of subtalar joint motion flexion. The lateral ligament complex to adapt to changes in terrain. When a S

(Renstrom et al, 1988). The role of the is therefore vulnerable to injury during the subtalar joint is in a neutral position, y b

PTL is unclear and controversial dorsiflexion, plantar flexion and inver­ the joints of the foot, ligaments and ten­ d e (Rundle 1995, Renstrom and Konradsen, sion. dons of the foot are least stressed. c u d o 18 SA Jo u r n a l o f Physiotherapy 2000 V o l 56 No 1 r p e R This is the position in which the foot terminal swing and pre-swing. The may well result in dysfunction of, and best supports the body’s weight (Heil, swing phase is divided into initial swing, pain in, the other joints of the lower limb 1992). mid swing and terminal swing (Norkin and spine, especially the knee, midtarsal and Levangie, 1992; Donatelli, 1996). and forefoot joints. 3. Midtorsal Joint At initial contact, (See Table 1) the This joint complex consists of the cal­ heel strikes the ground on its lateral ABNORMAL BIOMECHANICS caneocuboid and talonavicular joints, aspect. The body’s weight is transmitted Abnormal pronation and supination which link the subtalar joint with the down through the tibia and talus, which result in hypermobility and hypomobility forefoot. Due to the shape of the arti­ is medial to the ground reaction force. of the foot respectively (Donatelli, cular surfaces, the movements in the This results in adduction of the talus, 1996). midtarsal joint occur in combination, i.e. which initiates and produces pronation The overpronated foot can be recog­ plantar flexion and adduction occur with of the foot. The pronation ‘unlocks’ the nised by an everted calcaneus, medial supination, and dorsiflexion and ab­ midtarsal joint, allowing the foot to bulging of the navicular tubercle, abduc­ duction occur with pronation (Donatelli, absorb shock and adjust to the terrain. tion of the forefoot relative to the rear- 1996). Supination occurs during early mid- foot and a reduced height of the medial stance, bringing the foot to a neutral longitudinal arch (Donatelli, 1996). NORMAL BIOMECHANICS position at midstance. Supination conti­ This should be assessed in standing. The normal biomechanics of the foot nues during the midstance and toe-off Abnormal pronation results in a and ankle depend on static and dynamic (pre-swing) stages. This is essential as reduced time for resupination of the foot components. The bones, articular sur­ supination ‘locks’ the midtarsal joint to occur (Paulsen, 1991). The forefoot face congruity, ligaments and fascia con­ making the foot into the rigid lever nec­ remains unlocked and hypermobile, stitute the static component. The dyna­ essary for effective push-off. which reduces its ability to bear weight, mic component depends on muscle work During the swing-through phase the and substantially reduces its effective­ and movement of the tarsal bones. The foot moves from plantar flexion to ness as a rigid lever for push-off. If this is functions of the foot and ankle are to dorsiflexion and is relaxed. the case, soft tissues break down, muscle provide: Just before initial contact (heel strike), functions change and bony remodeling i. a flexible base to adapt to uneven tibialis anterior contracts to produce may occur. These changes may produce

) surfaces. dorsiflexion and this results in slight a secondary rigid deformity, which .

3 ii.support for the body’s weight in both supination of the foot. At initial contact mimics the oversupinated foot in its 1

0 static (standing) and dynamic (walk­ (heel strike), therefore, the foot is inability to absorb shock and adapt to 2

d ing) positions. supinated and rigid. As the lateral aspect changes in terrain (Donatelli, 1996). e t

a The talocrural, subtalar and midtarsal of the heel connects with the ground, The overpronated foot is associated d

( joints work together. the talus adducts, initiating pronation with overuse injuries. James et al (1978) r e once more. established that 58% of patients with h s

i During walking, the gait cycle is During gait, the muscles initiate overuse injuries overpronated their feet. l b divided into the stance (weight bearing) movement, stabilize the bones and Chronic inflammation, as found in u P

and swing phases. Traditionally, the decelerate movement. This unloads the overuse injuries, results in large num­ e

h stance phase is further divided into heel ligaments and joints (Donatelli, 1996) bers of fibroblasts in the area causing t

y strike, foot flat, midstance, heel off and e.g. tibialis anterior contracts maximally increased collagen production. This b toe off (Norkin and Levangie, 1992). immediately after heel strike to deceler­ increased collagen reduces joint mobi­ d e t The gait laboratory at Rancho Los ate the tibia and prevent a posterior lity and soft tissue extensibility. n

a Amigos Medical Center describes the shearing force at the talocrural joint, and During midstance the foot is pronated r g

subunits of gait by another set of terms. to control pronation of the foot. and not neutral. This creates a torque e c The stance phase is divided into initial Incorrect biomechanics will not only in the leg, as the foot is internally rotat­ n e contact, loading response, midstance, affect the ankle and subtalar joints, but ing as the hip is pushed into external c i l r e

d TABLE 1. The phases of gait, comparing the Traditional and Rancho Los Amigos nomenclatures. (Adapted from n "Donatelli R 1996 The biomechanics of the foot and ankle. Second Edition. Philadelphia: F A Davis Company" u y a Stance Phase Swing Phase w e t a

G Traditional Heel Foot Midstance Heel off Toe off Acceleration M idsw ing Deceleration t e strike flat n i b a

S Initial Loading Midstance Initial Terminal

Rancho Los Amigos Terminal Pre­ M idsw ing y b

contact response swing swing swing swing d e c u d SA Jo u r n a l o f Physiotherapy 2000 V o l 56 No 1 19 o r p e R rotation by the swing-through action of excessive pronation at the subtalar joint. of function includes sequential loading the opposite leg (Heil, 1992). The over- The intrinsic foot muscles should also of the tendons and ligaments; returning pronated foot may produce knee symp­ be strengthened. If there are any signs the normal range of motion; flexibility toms, especially medially. The normal of neural tissue involvement, techniques and muscle strengthening; propriocep­ cephalad and external rotation move­ should be used to increase neural mobil­ tive retraining; endurance training and ments of the fibula during weight bearing ity as described by Butler (1991). cardiovascular fitness. are also reduced, resulting in dysfunc­ Patient education and proprioception The healing process can take months. tion of the superior tibio-fibular joint exercises should be included through all To achieve successful rehabilitation, and pain (Donatelli, 1996). stages of healing. the patient has to become involved and The oversupinated foot lacks pro­ The incidence of re-injury is decreased responsible. This can only be achieved nation, making the foot rigid. This can with the restoration of normal biome­ by education and motivation of the increase ankle lateral ligament stability chanics of the foot and ankle. Restoration patient. problems and pain due to reduced shock absorption e.g. lateral knee pain and stress fractures. The oversupinated foot has an inverted REFERENCES calcaneus, a high medial arch and fore­ foot plantar flexion - again, this needs to Boruta P, Bishop J, Braly W, Tullos H 1990 Mooney M, Maffey-ward L 1995 All heel pain be assessed in a weight-bearing position Acute lateral ankle ligament injuries: A litera­ is not . Physiotherapy Canada (Donatelli, 1996). ture review. Foot Ankle 11(2): 107-113 47(6): 77-86

MANAGEMENT PRINCIPLES Butler D 1991 Mobilisation of the nervous Norkin C, Levangie P 1992 Joint structure and The general principles of managing system. Singapore: Churchill Livingstone function: A comprehensive analysis. Second patients with foot and ankle injuries are Edition. Philadelphia: F A Davis Company to: i) identify and treat the precipitating Chazan 1 1998 part 1: Anatomy, histology, classification, etiology Paulsen T 1991A review of injuries in runners. factors (biomechanics) and pathomechanics. Journal of Manual Sports Medicine 6(5): 4 - 8 ) . ii) estimate the stage of healing of the Manipulative Therapy 6(2): 63 - 69 3

1 injury 0 Rasmussen O 1985 Stability of the ankle joint. 2 iii) determine the focus of the initial

d treatment Chazan 1 1998 Achilles tendinitis part II: Analysis of the function and traumatology e t Clinical examination, differential diagnosis of the ankle ligaments. Acta Orthopaedica a iv) control the pain and inflammation d and approaches to management. Journal of Scandinarica Supp 211: 1-75 (

v) initiate an appropriate tensile loading

r Manual Manipulative Therapy 6(2): 70 - 77 e programme (Chazan, 1998) h s i Reid D 1992 Sports injury assessment and l b It is essential to identify the source Donatelli R 1996 The biomechanics of the rehabilitation. New York: Churchill u

P foot and ankle. Second Edition. Philadelphia: Livingstone.

and contributing factors of painful e F A D avis Com pany h inflammation of the ankle and foot to t

y ensure proper diagnosis and treatment Renstrom P, Wertz M, Incavo S 1988 Strain in b Garrick J 1977 The frequency of injury, mech­ the lateral ligaments of the ankle. Foot Ankle d (Mooney and Maffey-ward, 1995). e t In the acute inflammatory stage, the anisms of injury and epidemiology of ankle 9: 59-63 n sprains. American Journal of Sports Medicine a principles of PRICE (protection, rest, r

g 5: 241 - 2 4 2 ice, compression and elevation) are used e Renstrom P, Konradsen L 1997 Ankle ligament c to minimise the inflammatory response n injuries. British Medical Journal 6: 10 - 18 e c and decrease the pain, enhancing the Heil B 1992 Lower limb biomechanics related i l to running injuries. Physiotherapy 78(6): 400 r conditions for healing (Donatelli, 1996). e - 4 0 6 Rundle E 1995 Foot and Ankle. In: Zuluaga d The contributing biomechanical factors

n Metal eds. Sports Physiotherapy - Applied

u should be addressed through the wearing Science and Theory. New York: Churchill y of corrective footwear or foot orthoses, a James S, Bates B, Ostering L 1978 Injuries Livingstone: 643 - 678 w as well as appropriate mobilisation and e to runners. American Journal of Sports t

a strengthening (Heil, 1992). External Medicine 6: 40 - 42

G Schrier I 1995 Treatment of lateral collateral cushioning, cupping or taping of the heel t

e ligament sprains of the ankle: A critical

n can improve shock absorbency and i McCulloch P, Holden P, Robson G 1985 The appraisal of the literature. Clinical Journal of b allow early weight bearing (Schrier, a value of mobilisation and nonsteroidal anti­ Sports M edicine 5: 187 - 195 S 1995). Increased strength and flexibility inflammatory analgesia in the management y b of the posterior calf muscles may de­

of inversion injuries of the ankle. British d Journal of Clinical practice 39: 224 - 230 e crease weight-bearing forces, preventing c u d

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