Most common injury in sports and recreational activities (Renstom and Konradsen 1997)
Accounts for 25% of all sports related injuries Frost and Amendola (1999)
The ligaments around the ankle are the most commonly sprained ligaments in the body (Hertling and Kessler 1996). Yeung et al (1994) reported that of 563 sprained ankles, 73.5% had been sprained more than once. Frost and Amendola (1999) state that even with treatment there is a 50% chance of recurrent instability.
Anatomy, and likely sites of neural pathology.
The talocrural joint is collaterally restrained by the lateral and medial, or deltoid, ligament complexes. The lateral ligament is the most frequently injured. The lateral ligament consists of the anterior talofibular, calcaneofibular, lateral talocalcaneal and posterior talofibular ligaments.
Local sites – Common peroneal nerve, sural nerve.
Remote sites – Common peroneal nerve at the head of the fibula, sciatic nerve, at the sciatic bifurcation in the lower part of the thigh where it splits into the common peroneal and posterior tibial nerves. L4-S3 (Sciatic nerve) and preganglionic fibres for the lower limb which arise from T10-L2.
Types of instability:
Mechanical – a deficiency of the stabilising structures around the joint which allows joint movements beyond normal physiological limits (Frost and Amendola 1999). Most commonly at the Talocrural joint, or less commonly, at the subtalar joing, Ishi et al 1996).
Functional – less well understood, but Freeman et al. (1965) describe it as ankles which suffer from recurrent sprains or a tendency to “give way”.
Mechanial – most widely used is the anterior draw test, assessing the amount of anterior translation fo the talus relative to the fibula and tests the integrity of the anterior talofibular ligament. A good predictor of ligament disruption (Renstom and Konradsen 1997). However, Bonstrom (1996) found the anterior draw sign was only consistently positive in the presence of local anaesthesia. Van Dyjk et al. (1996) found that the test was unreliable if performed within 48hrs of the injury, but if performed after the 5th day then it showed a specificity of 74% and a sensitivity of 86%.
Functional – This diagnosis can only be obtained through a subjective assessment, it cannot be demonstrated by any imaging technique (Jerosh and Bischoff 1996).
Muscle weakness has been considered as a cause of instability, however McKnight and Armstrong found no significant difference between injured and non-injured muscle groups. Although Wilkerson et al.(1997) found that, paradoxically, the invertors had the greatest performance deficiency following the lateral ankle sprains.
Proprioception is also widely considered to be a major factor in maintaining joint stability. Research by Freeman et al. Reported in van der Eikoff and Osternig (1998) suggested that injury to ligaments and joint proprioceptors following ankle sprains would decrease the effectiveness of the reflexes associated with joint receptors. Various studies have found that the proprioceptive abilities of sprained ankles were significantly worse than unaffected ankles (Lentell et al. 1995, Konradsen and Magnusson 2000, Lofvenberg et al. 1995).
Because of the passage of the superficial peroneal nerve over the anterolateral aspect of the ankle, the nerve is tensioned and moves distally in the leg with plantarflexion/inversion of the foot and ankle (Shacklock 2005). Some ankle sprains produce damage in this nerve which may account for peroneal neurodynamic tests (Slump and SLR versions) becoming abnormal in some patients with sprained ankles. Plantarflexion/inversion of the ankle is valuable in the sensitization of peroneal involvement in lower limb pain. Damage to the peroneal nerve can occur as high as the common peroneal nerve at the posterior aspect of the knee where haematomas can develop after traction injury caused by the sprain. Compromise can also occur as far distally as the superficial peroneal nerve. Inflammation then develops and the nerve may incur hypersensitivity, reduced mobility and in some cases, reduced conduction. The clinical picture is one of pain with movement, particularly plantarflexion/inversion, tenderness and aching, dysaesthetic symptoms, tenderness and in cases where there is reduced conduction- a loss of sensation. In more recalcitrant cases, severe mechanical allodynia related to central sensitization may be a prominent feature. Loss of muscle power due to paralysis is not nearly as common as the other symptoms, but should be kept in mind.
Testing.Level 1:Straight leg raise with the foot relaxed. At the height of the SLR, if symptoms have not been provoked, the foot is passively moved into plantarflexion/inversion to the onset of symptoms. At this point, to differentiate the neurodynamic mechanisms the limb is lowered by reducing the hip flexion angle a small amount, whilst holding the foot stationary on the leg.Level 2:The same sequence as above, except that the foot is placed in plantarflexion/inversion prior to the SLR. Ensure there is no uncontrolled internal rotation of the hip.Level 3:a) add internal rotation of the hip prior to SLRb) plantarflexion/inversion taken further into range even evoking symptons prior to SLR. Ensure toes are included in the movement.c) As above but add resisted dorsiflexion/eversion to apply force through the mechanical interface (bone and tendon) and innervated tissues.
Webborn (1999) states that restoration of strength, range of motion and proprioceptive awareness are imperative prior to returning to training, and goes on to say that protective bracing may be required in the early stages. Cote et al. (1988) found that cold therapy significantly reduced the oedema in ankle sprains that were post acute. Cryotherapy also has a pain relieving effect by reducing the nerve conductivity (Thompson et al. 1991). van der Eikoff and Osternig (1998) have postulated that the application of external supports stimulate cutaneous receptors which may increase proprioceptive feedback. Karlsson and Andreasson (1992) found that reaction times of the peroneus muscles were shortened when unstable ankles were taped, so therefore they deduced the proprioceptive effect of taping was to restrict the extreems of ankle motion and to help shorten the reaction time of the peroneus muscles. Eilis and Rosenbaum (2001) carried out research into the effects of proprioception exercises for the ankle, they results showed a significant improvement in joint position sense and postural sway as well as significant changes in muscle reaction times. Goldie et al. (1994) found that eight weeks post injury, those who and received no proprioceptive training had significant worse static posture control that those who had received proprioceptive training.
Neural Treatment. Level 1 Proximal sliders. Patient supine, hip at 45degrees, supported by therapist. Knee flexion and plantarflexion/inversion. Level 2 Tensioners. Ipsilateral long sitting position and leaning forwards over the hip at the same time as performing plantarflexion/inversion. Stabilise the knee in extension if required. Level 3 a) Tensioners as above, but add internal rotation of the hip and contralateral side flexion with the slump. b) start with foot plantarflexed/inverted and knee flexed, extend the knee and then add hip flexion, Lx flexion, and Cx flexion, in that order. c) as per 3a but with active dorsiflexion against the therapist and contract-relax releases are performed at the end of range. If the joint is also stiff it is possible to mobilise the joint in conjunction with the neurodynamic techniques. Sural nerve. When there is a history of severe adduction of the calcaneum or dorsiflexion/inversion of the ankle the sural nerve can be affected. This is because the nerve passes around the dorolateral surface of the ankle posterior to the lateral malleolus. The sural nerve may also cause pain in the region of, and coexist with stiffness in the joints that surround, the cuboid bone. Biomechanics are therefore very important aspects of the assessment. Testing: similar to the peroneal nerve, but with dorsiflexion/inversion