Pathomechanics of Ankle joint

DESCRIBED ABOUT ALTERED NORMAL MECHANICS AT PATHOLOGICAL ANKLE

1. PATHOMECHANICS OF ANKLE JOINT R.P.SHANMUGA PRIYA

2. ANATOMY

3. LIGAMENTS

4. MUSCLE GROUP AND ITS ACTION

5. MECHANIC OF ANKLE MOTION

6. PATHOMECHANICS MEDIAL LIGAMENT INJURIES Eversion type of sprains Less common than the inversion type partly because of the presence of the lateral malleolus .  bony protrusion reduces the length of ligament exposed to the sheering forces that can could cause ankle sprains. Additionally, the medial ligaments, are stronger compared with lateral ligaments. These shorter ankle ligaments are so strong that tearing them usually requires enough stress and force to fracture the tibia or even fibula. Therefore, eversion -related ankle sprains should be checked in conjunction with fractures as they commonly occur together. In addition, the tibia, fibula, or even talus may be fractured, making eversion sprains particularly severe.

7. LATERAL LIGAMENTS INJURY Inversion type of sprains Most common type of ankle sprain Happens due to unstable landing after a jump or running/walking on an uneven surface. It results from the plantarflexion of the foot injuring the ATFL the ligament involved moves perpendicular to the talus, exposing it to shear forces. A lot of force applied to the ATFL during the inversion sprain may break it and affect the CFL. The effect occurs because the CFL is the next ligament supposed to take the stress. The CFL can be injured if the inversion sprain is extreme enough.

8. Inversion sprains that result in the tearing of the ATL usually lead to an unstable ankle joint only during plantarflexion . If both the ATL and CL tear, the joint becomes unstable in any position of foot. One interesting observation that also stresses the complexities of the ankle joint and its injuries is the results of dorsiflexion after ankle sprains that tear both the CL and ATL. Injuring both the anterior and posterior tibiofibular ligaments makes the ankle joint unstable

9. ` Some unique forms of ankle sprains involve the syndesmotic ligaments that connect the ankle joint to the bones forming the shin. This type of sprain is common among footballers and result in persistent pain as well as residual ankle dysfunction. Require almost twice as long to heal compared with inversion and eversion sprains. One reason for such lengthy healing periods is the syndesmosis ligament, which is hard to heal. Surgery is a common form of treatment for cases where the high ankle sprain is serious and the syndesmosis lIgaments are torn.

10. These sprains occur in three distinc t manners. The first is external rotation of the foot. When done in a forceful manner as in sports like skiing and soccer, it may widen the ankle mortise due to the talus being driven into the mortise by external rotation. The second manner a high ankle sprain may occur is eversion of the talus in a forceful manner leading to the mortise widening. Such action also exerts a lot of strain on the high ankle ligaments because the entire ankle shifts with the talus injuring the syndesmotic ligament. The third way a high ankle sprain may happen is, which widens the mortise because the wider anterior aspect of the nearby talar dome invades the joint space. If the dorsiflexion occurs forcefully, as in sports such as soccer and rock climbing, the distal fibula is pushed away laterally and prevented from engaging with the distal fibula in its normal articulation manner.

11. MUSCULAR IMBALANCES TIBIALIS ANTERIOR Weakness Tightness 11 Severely weakens the dorsiflexion but not eliminates. Loss causes inability to control the foot after heel contact during locomotion, foot slap Weakness tibialis anterior along with weakness of other dorsiflexor muscles may lead to foot drop Isolated weakness causes unopposed peroneus causing plantar flexion of the first metatarsal Causes cavus foot, pulling forefoot medially accenuating the medial longitudinal arch

12. Extensor Hallucis Longus weakness Tightness 12 Weakens the extension at the metatarsophalangeal and interphalangeal joints of great toe Claw toe deformity, extensor hallucis longus pulls the MTP joint of great toe into extension, which causes flexion of IP joints of great toe as flexor hallucis longus is stretched.

13. Extensor digitorum longus Weakness Tightness 13 Decreases ability to lift the toes from the ground during the swing phase of gait Claw toe deformities extensor digitorum longus pulls the MTP joint of toes into extension, which causes flexion of IP joints of toes as flexor digitorum longus is stretched

14. Peroneus tertius Weakness Tightness 14 Occurs in conjuction with weakness of the extensor digitorum longus and the other dorsiflexor muscles. Occurs concomitantly with extensor digitorum longus .

15. Gastrocnemius Weakness Tightness 15 Decreased plantar flexion strength Hampers an individual ability to rise up on toes or climb hills or ladders Decreases ROM of dorsiflexion Depends on position of knees

16. Soleus Weakness Tightness 16 Plantar flexion strength is lost Impairs the leg control ability as the body glides over the stance foot Tightness of the soleus also restricts dorsiflexion ROM Plantarflexion contracture is independent of knee position. Restricts forward glide of the tibia, even though momentum may continue the forward progression of the thigh and trunk Tightness of the soleus is a risk factor for genu recurvatum .

17. Deep Muscles Of The Posterior Compartment Posterior Tibialis Weakness Tightness 17 Impairs inversion strength. Impairs an individual’s ability to rise up on the toes, even with intact plantarflexor muscles, because the foot is unstable. Imbalance with the everter muscles, and the foot tends to evert and abduct; that is, it tends to pronate . Pulls the foot into inversion and adduction of the forefoot and may include slight plantarflexion , producing a varus or an equinovarus deformity of the foot. Such deformities are often found in individuals with spasticity of the posterior tibialis or with an imbalance between the posterior tibialis and the everters of the foot.

18. WEAKNESS 18 Patients with posterior tibilalis tendon dysfunction (PTTD) exhibit increased pronation at the hindfoot and forefoot, reflecting the muscle’s extensive role in supporting most of the foot . PTTD is a primary cause of acquired flat feet and alters the normal movement of the tarsal bones during weight bearing and gait . Factors associated with increased risk of PTTD are obesity, aging, hypertension, diabetes, and vascular insufficiency within the tendon . A preexisting flat foot deformity also appears to be a risk factor for a rupture of the posterior tibialis .

19. Flexor Digitorum Longus Weakness Tightness 19 Produces weakness in toe flexion MOSTLY at the distal interphalangeal joints. Functionally, weakness of the flexor digitorum longus produces difficulty in stabilizing the foot and toes during stance and is manifested by delayed or limited heel rise as the body rolls over the foot. Tightness of the flexor digitorum longus impairs extension ROM of the toes.

20. Flexor Hallucis Longus Weakness Tightness 20 weakens flexion of the great . contributes to decreased plantar flexion strength. Weakness may also contribute to slight inversion weakness Limits extension of the joints of the toes particularly when the ankle is dorsiflexed . Plantarflexing the ankle puts the muscle on slack and allows more toe extension . Tightness of the flexor hallucis longus also is implicated in a claw deformity of the great toe, may also contribute to foot pain in the medial longitudinal arch. Runners occasionally develop pain along the flexor hallucis longus tendon as the result of repeatedly stretching the contracting muscle during the push off phase of running

21. MUSCLES OF THE LATERAL COMPARTMENT OF THE LEG Peroneus Longus Weakness Tightness 21 Weakness of the peroneus longus contributes to weakness in eversion of the foot. the inverters, particularly the posterior tibialis , pull the foot into inversion or inversion with plantarflexion , and a varus , or equinovarus , deformity Limit inversion ROM of the subtalar joint, tightness is manifested primarily by a plantarflexed first ray. In weight bearing the plantarflexed first ray may produce excessive loading on the metatarsal head of the great toe which can lead to pain and large callus formation under the first metatarsal head Weight bearing in upright stance with a plantarflexed first ray also produces a supination moment on the foot.

22. Peroneus Brevis Weakness Tightness 22 Weakness of the peroneus brevis decreases eversion strength and contributes to an imbalance between the inverter and everter muscles. increases the relative contribution of the inverters and leads to a varus hindfoot deformity . tightness of the peroneus brevis may contribute to valgus deformities of the foot. weakness of the posterior tibialis or overactivity of the extensor digitorum longus also are important contributors to valgus deformities of the foot.

23. Fractures 23 Malleolar fracture and their classification Supination – Abduction injuries Inversion force on the dorsiflexed ankle results in vertical or oblique malleolar fracture and transverse avulsion type fracture of distal fibula associated rupture of the lateral collateral ligament. This is also associated with medial displacement of talus. Supination -External rotation This is the most common type of injury. This leads to typical oblique fracture at distal fibula and either a transverse or avulsion type of medial malleolus fracture and rupture of the deltoid ligament.

24. 24 Pronation -Abduction injuries there will be deltoid ligament disruption and transverse fracture of the medial malleolus with short oblique fracture of fibula at the level of syndesmosis with lateral communiation fracture. Pronation -External rotation injuries transverse fracture of the medial malleolus or rupture of the deltoid ligament may occur. This can be associated with disruption of the tibiofibular ligament and fracture of the posterior part of the distal articular surface of tibia, that is, posterior malleolar fracture.

25. 25 POTT’S FRACTURE Described by percival Pott in 1765. Combined abduction and external rotation violence It includes rupture of the medial ligament/ fracture of medial malleolus , fracture of lateral malleolus and lateral displacement of ankle.

26. 26 VERTICAL COMPRESSION FRACTURES Caused by fall from heights on the heels. Fractures of the intra- articular distal tibia called pilon fracture

27. 27 Chronic ankle instability (CAI) is a term that is presently used to denote the occurrence of repeated episodes of lateral ankle instability and the presence of residual symptoms such as pain, swelling, ‘‘giving way,’’ and loss of motion Potential intrinsic risk factors for the development of ankle instability due to, ligamentous stability,muscular strength,anatomic foot and ankle alignment, postural sway, gait mechanics, and muscle reaction time..

28. 28 Two main types of instability can be distinguished: Mechanical instability related to anatomic abnormalities of the ankle, usually related to ligament laxity. Functional instability related to posture defects or tendon and muscle adjustment, usually related to a proprioceptive deficit.

29. 29 Mechanical instability Bone instability: Unstable ankles can present a congruence defect with a wider talar dome and reduced talar coverage as well as a more anterior position of the talus in relation to the tibia on the loading. The lateral malleolus seems to be in a posterior position because of distension or rupture of the anterior talofibular ligament, from medial rotation of the talus (notably in pes cavus ), or from malunion of the lateral malleolus .

30. 30 Mechanical ligament instability. Ankle instability does not result only from injury, constitutional hyperlaxity also exists. These can be a stimulation defect of the joint mechanoreceptors or proprioception dysfunction. Mechanical joint instability The wider talus at the front explains that the deficit in dorsal flexion of the ankle is a factor of instability. Therefore, anterior osteophytosis (impingement exostosis ) or anterior synovial hypertrophy (fibrous impingement) are factors aggravating instability. This limitation in dorsi - flexion can also have a functional cause such as retraction of the sural triceps or the gastrocnemial muscles or even a muscle belly extended too far distally.

31. 31 Functional instability Functional muscular instability. The delay in muscle reactivity can be caused by a sometimes transitory neurological deficit (paresis after sitting with the legs crossed) or a mechanical muscle defect (muscle belly developed too distally, tenosynovitis or luxation of the fibularis muscles). In a gait analysis, an increase in dorsal flexion of the first metatarsophalangeal joint, an increase in ground contact time, lateralization of pressure of the lateral edge of the midfoot and the forefoot, and an increase in the pronosupination index

32. 32 Functional postural instability. Varus of the hindfoot is a cause of ligament reconstruction failure . Varus results in excessive pressure on the lateral edge of the foot and postural imbalance in monopedal weightbearing . It is responsible for excessive tension of the fibularis muscles, with most often a loss of the myotatic reflex. The associated equinus results in a contraction defect in the extensor digitorum muscles or, excess flexion with clawing of the lateral toes.

33. 33 Clawing of the fifth toe or a callus under the head of the fourth metatarsal is also a sign of ankle instability. Other morphostatic problems induce excessive pressure on the lateral edge of the foot such as unequal length of the lower limbs in which the shorter limb tends to position itself in varus-equinus , with genu varum , adductus foot, or forefoot pronatus , causing an unstable dynamic supination movement on weightbearing

34. RECENT ARTICLES Lateral and syndesmotic ankle sprain injuries: a narrative literature review. Dubin JC 1 ,  Comeau D ,  McClelland RI ,  Dubin RA ,  Ferrel E Epub 2011 Jul 23.  to review the literature that discusses normal anatomy and biomechanics of the foot and ankle, mechanisms that may result in a lateral ankle sprain or syndesmotic sprain Most ankle sprains respond favorably to nonsurgical treatment, such as those offered by physical therapists, doctors of chiropractic, and rehabilitation specialists. An accurate diagnosis and prompt treatment can minimize an athlete's time lost from sport and prevent future reinjury .

35. 2010 Jul 16;1:115-22.PUBMED Ankle sprain: pathophysiology , predisposing factors, and management strategies. Hubbard TJ 1 ,  Wikstrom EA . review LAS pathophysiology , predisposing factors, and the current evidence regarding therapeutic modalities and exercises used in the treatment of LAS Recent evidence has shown the need for more stringent immobilization to facilitate ligament healing and restoration of joint stability and function after a LAS

36.   Epub 2009 Jul 17PUBMED. Reinjury after acute lateral ankle sprains in elite track and field athletes. Malliaropoulos N 1 ,  Ntessalen M ,  Papacostas E ,  Longo UG ,  Maffulli N . The effect of a lateral ankle sprain on reinjury occurrence in the same region. Athletes with a grade I or II lateral ankle sprain are at higher risk of experiencing a reinjury . Low-grade acute lateral ankle sprains result in a higher risk of reinjury than high-grade acute lateral ankle sprains.

37. References: 37 Application to Pathological Motion ;Gary L. Soderberg Kinesiology of the Musculoskeletal System: by  Donald A. Neumann   The Mechanics and Pathomechanics of Human Movement Carol A. Oatis Joint Structure and Function : A Comprehensive Analysis, Pamela K. Levangie  Cynthia C. Norkin   WEB SEARCH : pubmed , pedro , science direct