The Ankle And Foot

Chapter 12 The Ankle and Foot


The ankle and foot perform two major roles: they support the body and propel it forward. In the process of performing these functions, several painful conditions may develop. Many of these develop in the forefoot and are often the result of poorly fitted shoes.



Anatomy


The ankle is a hinge joint composed of the articular surfaces of the lower portion of the tibia, talus, and medial and lateral malleoli (Fig. 12-1). The stability of this joint or “mortise” is maintained by the malleoli and their ligaments, which grasp the talus and prevent medial and lateral displacement. The talus and socket are both broader in front, an arrangement that provides maximum stability when the ankle is in dorsiflexion or neutral, and this prevents posterior displacement. Only movements of dorsiflexion and plantar flexion occur at the ankle.



The foot is composed of 26 bones, 12 of which are components of the medial and lateral longitudinal arches (Fig. 12-2). Strong fascial supports maintain these arches and prevent collapse (Fig. 12-3). Eversion and inversion movements of the foot take place in the hindfoot at the subtalar joint. Injury or disease that affects this joint will cause pain in the region of the heel when walking on uneven or irregular surfaces. Abduction and adduction movements occur in the midfoot or midtarsal joints.




During normal walking, when the heel strikes, the calcaneus everts to cushion impact. At the toe-off position, the heel then rolls into varus to provide power.



Flatfoot


Flatfoot is a common disorder that is defined as a depression or loss of the medial longitudinal arch of the foot. It is usually combined with valgus or eversion of the heel and abduction of the forefoot. An apparent flatfoot (“fat foot”) is present in many children up to the age of 2 years because of the presence of a fat pad in the area of the longitudinal arch. As the fat pad atrophies with weight bearing, the normal arch usually becomes visible. Flatfoot is usually one of two types: flexible or rigid. It occurs in conjunction with an accessory navicular bone in the foot, and it also results when a rupture of the posterior tibial tendon has occurred. It is also seen in the late stages of Charcot arthropathy, when collapse and reversal of the longitudinal arch can develop.





ClINICAL FEATURES


Symptoms are rare but may consist of pain, burning, and easy fatigability. With weight bearing, the heels are everted, and the forefoot appears pronated and abducted (Fig. 12-4). The child often “breaks down” the medial counter of the shoe. When it is not bearing weight, the foot often looks normal. Absence of the medial arch is apparent, and the foot is mobile without any fixed deformity. The child with flatfoot can usually form a good arch when asked to stand on tiptoe. The heel rolls into its usual varus position, and normal strength is apparent. A mild genu valgum (knock-knee) or internal tibial torsion may be present. With the heel inverted, passive dorsiflexion of the ankle will be limited if the heel cord is tight.



A lateral roentgenogram taken with the foot bearing weight may reveal a loss of the normal arch and plantar flexion of the talus (Fig. 12-5). Some secondary bony changes may be present in the adult.






RIGID FLATFOOT


Rigid or peroneal spastic flatfoot differs from flexible flatfoot in that the deformity is not passively correctable and is present whether weight bearing or not. This condition is usually secondary to a tarsal coalition or arthritis in the hindfoot. Tarsal coalitions are congenital cartilaginous or bony bridges that may be found between the two bones of the hindfoot or between either of these bones (usually the calcaneus) and the navicular. The resultant loss of motion in the hindfoot leads to local irritation and protective “spasm” in the peroneal muscles, producing the flatfoot appearance. This may be caused by attempts at compensation by the muscles to correct the alignment by pulling against the deformity. The condition is bilateral in half of the cases. Most cases of coalition are not symptomatic.






POSTERIOR TIBIAL TENDINOPATHY/RUPTURE


The posterior tibial tendon is commonly involved in a spectrum of overuse disorders. These can range from simple acute pain as a result of tendinitis to complete rupture. The underlying pathology is now considered to be more degenerative than inflammatory, perhaps the result of some distant traumatic event with ischemia. Although the name tendinitis is still used, these disorders are often discussed under the general term tendinopathy or tendinosis because inflammatory pathology is usually absent, hence the changing terminology.


Simple degeneration causes painful medial swelling and tenderness along the tendon sheath. There is usually no history of trauma, and the onset of symptoms is insidious. Stretching the tendon increases symptoms, and active inversion reproduces pain. Weight bearing is difficult. Treatment includes NSAIDs, gentle stretching, rest, orthotics, and the use of a cast boot. Steroid injections are probably not indicated because they could lead to further weakening of the tendon.


Further deterioration of the tendon could lead to rupture and the development of an acquired flatfoot deformity. Overuse, attrition, and failure are the cause. (Acute rupture of healthy tendon is unusual.) The condition is common, but the diagnosis can be difficult and is often missed until the patient discovers the loss of the arch. Usually, there is a history of previous pain, and the patient may have even had treatment for “tendinitis” in the same area. There is often only minimal pain after rupture, probably because the tendon is no longer attached and is no longer subject to stretch. Normally, the posterior tibial tendon locks the heel in varus, but without it, the heel does not move into inversion with push-off, and the gait is thus weakened. Clinically, the tendon sheath may be empty, and the heel everts with weight bearing. The medial arch is lower, and swelling and mild tenderness may be present. Inversion of the heel and forefoot against resistance is weak. There is also difficulty in performing the single heel rise test, in which the patient tries to rise on the ball of the foot on the affected side (Fig. 12-8). Heel valgus and forefoot abduction also increase gradually, and, as a result, when looking from behind, “too many toes” are visible with the patient standing (Fig. 12-9).




Patients with complete ruptures and partial ruptures that do not respond to medical treatment should be referred. Many patients with complete rupture do well with nonsurgical care and do not require reconstruction.






Ankle Sprains


The sprain is the most common of all ankle injuries and may be the most common injury in sports. Most of these (85%) involve the lateral ligament complex as a result of excessive inversion. Medial sprains involving the deltoid ligament are rare. The anterior talofibular (ATF) ligament is usually injured first in the typical lateral sprain (Fig. 12-13). More severe injuries involve the calcaneofibular (CF) ligament. Only rarely is the posterior talofibular ligament involved. The injuries are often graded I, II, and III, with I being mild and II being moderate. Grade III injuries are more severe, with instability resulting from rupture of the ATF and CF ligaments. Inversion (varus) sprains may also cause marked hemorrhage of the peroneal muscles and even peroneal nerve damage. The subtalar joint may also be injured.



Other ligamentous ankle injuries are much less common, but the anterior inferior tibiofibular (AITF) ligament, deltoid ligament, and interosseous membrane may be involved in eversion and rotational injuries. Damage to the tibiofibular syndesmosis is sometimes called a “high sprain” because of pain above the ankle from injury to the interosseous membrane. On rare occasions, the fibula may even be separated from the tibia.




CLINICAL FEATURES


The symptoms will depend on the severity of the injury. There is often a history of a “pop” at the time of injury. Mild sprains may cause only slight loss of function, but with more severe injuries, swelling and pain are significant and prohibit further use of the limb. Syndesmotic sprains often appear more benign because of minimal swelling. However, the pain and disability are greater than the clinical appearance would suggest, and the patient may be unable to bear weight.


Physical examination is important. Hemorrhage and local tenderness are present at the site of injury. Careful palpation can localize the site of damage. Tendon function should be assessed, and any bony tenderness should be noted. The clinical evaluation of stability is sometimes helpful since it may determine the course of treatment, although this part of the examination may need to be deferred because of pain. Stability of lateral injuries can be assessed by the anterior drawer and talar tilt tests (Fig. 12-14). The anterior drawer is the most reliable test and least painful in the acute stage. Positive test results indicate complete rupture of the ATF and CF ligaments and a grade III injury. Motor function should always be evaluated.



In syndesmotic injuries, the area of tenderness is more anterior and proximal. Dorsiflexion of the foot and compressing the ankle mortise (the “squeeze” test) may provoke pain, and the ankle may feel spongy.


Roentgenographic evaluation is always performed, and because the mechanism of injury that causes a lateral sprain is the same as that which causes an avulsion fracture of the base of the fifth toe, the film should include the fifth metatarsal base to rule out fracture of the small toe. If the injury is in a child or adolescent with open growth plates, tenderness over the fibular malleolus (even with normal roentgenographic findings) implies the more likely growth plate fracture rather than a lateral sprain, and a cast is usually necessary. Opinions vary on the usefulness of arthrograms, tenograms, and stress films (Fig. 12-15). A good clinical examination is usually sufficient to determine stability.




TREATMENT


Regardless of the severity, almost all sprains are treated nonoperatively. At first, all injuries are elevated, and a soft compression dressing is applied for comfort and to help control swelling. Ice (1 hour on, 1 hour off) is applied, and crutches are used for ambulation. Rest, ice, compression, and elevation (RICE) are continued for 1 to 2 days. Anti-inflammatory medication has been recommended in the past for these injuries because it was thought that suppressing the local inflammation could allow faster recovery from sprains and other similar soft tissue injuries. The use of these drugs under these circumstances has been the source of considerable debate, mainly because prostaglandins play important roles in the healing process and these medications block their production. The effects of NSAIDs on soft tissue healing are not clear, and any apparent benefits may only be because of their analgesic effects. Whether these drugs are helpful or harmful in these cases has not been determined. Crutches are frequently needed for 2 to 3 days. Heat is never used.


The next phase of treatment is rehabilitation, which includes early active range-of-motion exercises (circumduction) and weight bearing as tolerated (Fig. 12-16). “Alphabet” exercises (writing the alphabet in capital letters with the great toe) are begun, and in 4 to 5 days, exercise against resistance is added. Wrapping or bracing with a stabilizing orthosis may also be helpful. Static bicycling may be added after 1 week, along with fast walking.



If the pain is particularly severe or the patient requires independence, a short leg walking cast may be applied for 2 to 4 weeks. A removable fracture cast boot is also a good option to control excessive pain.


Casting is used less frequently now because of concern over the temporary loss of motion and atrophy that occur, which require some time for restoration of function following cast removal. However, cast treatment has many advocates and should still be considered, especially in those patients who might require independent walking. Other options for painful sprains include various short leg orthoses that immobilize the ankle and foot, such as the ankle–foot orthosis (AFO). These are usually weight-bearing appliances that can be removed for exercise. They are worn for about 4 weeks. A compression stocking can help control swelling.


The treatment of severe sprains with instability remains somewhat controversial, but they are usually treated in the same manner as other sprains with a functional rehabilitation program. Although the results of surgical repair of unstable acute sprains are excellent, surgery is usually reserved for chronic instability in the high-level professional athlete or those with significant syndesmotic separations.


NOTE: Lateral sprains of any severity may also cause lingering symptoms for weeks and months. Some syndesmotic sprains take even longer to heal (55 days vs 35 days for lateral sprains), and heterotopic ossification may even develop in the interosseous membrane. (Unless symptoms occur, long-term results are not usually affected by such ossification.) If healing seems delayed, the following conditions should be considered: (1) talar dome fracture, (2) reflex sympathetic dystrophy, (3) chronic tendinitis, (4) peroneal tendon subluxation, (5) another occult fracture—such as that involving the anterior superior process of the calcaneus or the lateral process of the talus, (6) poor rehabilitation, and (7) the high sprain. Evaluation at this point should start by another clinical examination and simply repeating the plain roentgenograms (Fig. 12-17). CT, bone scan, or MRI may be indicated at a later time.



Ankles that are chronically unstable because of lateral ligamentous laxity may benefit from the application of a 0.3-cm lateral heel and sole wedge to prevent inversion. Taping or bracing during vigorous activities is also helpful, as are strengthening exercises. Continuing symptoms may require surgical reconstruction of the lateral ligaments to relieve symptoms of instability, although late traumatic arthritis or chronic instability is rare regardless of treatment.


NOTE: Evidence-based studies suggest the following: (1) there are no significant differences in outcomes between surgical and nonsurgical treatment of acute lateral ligament injuries of the ankle; and (2) ultrasound therapy appears to be of no benefit in the treatment of acute ankle sprains.



Tarsal Tunnel Syndrome


Nerve entrapment rarely may occur in the foot by compression of the posterior tibial nerve beneath the flexor retinaculum at the ankle. This retinaculum arises from the medial malleolus and inserts into the medial aspect of the calcaneus (Fig. 12-18). Space-occupying lesions, local tendinitis, traction injuries, fibrosis secondary to fractures, or deformities of the heel and foot can all compromise the tunnel and cause pressure on the posterior tibial nerve. The disorder is controversial, and there are many unanswered questions regarding its diagnosis and incidence.






Osteochondritis Dissecans of the Talus (Talar Dome Fracture)


This condition is characterized by the formation of a small area of necrotic bone on the articular surface of the talus. The cause is usually traumatic, and the medial aspect of the talus is the area most commonly involved. It is often the lesion causing persistent symptoms after a “sprain” that does not heal. The necrotic fragment may even become detached from its base, becoming a loose body.




Disorders of the Hindfoot



PLANTAR FASCIITIS (“PAINFUL HEEL SYNDROME”)


The plantar fascia extends from the calcaneus to the proximal phalanges of each toe and plays an important role in gait. It is a common site of pain that frequently develops near its attachment at the medial tubercle of the calcaneus and along the medial longitudinal arch. The etiology is probably overuse with the development of degeneration and microtears. The role of inflammation is unclear. Both heels are frequently affected. This bilateral involvement may be an early symptom of other inflammatory disorders, such as rheumatoid arthritis, gouty arthritis, or ankylosing spondylitis (when it is often referred to as enthesitis or enthesopathy). Risk factors include tight heel cords (reduced ankle dorsiflexion) and obesity. Men and women are affected equally, and runners are more often affected.




TREATMENT


Taping, relief pads, heel cups, cushions, and various orthoses have all been used with only modest success. Over-the-counter pads and cups are as effective as more expensive orthoses. No treatment designed to cushion the heel seems to help, probably because heel strike may not be the cause of the problem. Exercises that stretch the heel cord and plantar fascia may help, but they should not be performed in the acutely painful foot. Only a gentle pulling sensation should be felt. Cold or ice as counterirritants may promote temporary relief. A heel lift or high-heeled shoe may relieve pain in some cases. Oral anti-inflammatory medication is used as necessary. Many patients will benefit from local infiltration of the tender area with a steroid/lidocaine mixture (Fig. 12-23). The injection may be repeated three to four times. (Avoid injecting the superficial tissue, which could cause fat pad necrosis.) Application of a short leg walking cast or removable cast-boot for 6 weeks is often very beneficial. Custom-fitted tension night splints that hold the foot in slight dorsiflexion are used in some resistant cases. Physical therapy is not usually recommended. Extracorporeal shock wave therapy has even been tried, but the results are inconclusive.


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Jun 12, 2016 | Posted by in ORTHOPEDIC | Comments Off on The Ankle And Foot

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