WHAT’S YOUR DIAGNOSIS: Aged Woman Whose Toes “Point Like a Ballerina’s”

HISTORY An 86-year-old woman with advanced dementia of mixed Alzheimer and Parkinson type is seen for an annual comprehensive history and physical examination in the nursing home where she has resided for many years. No known diabetes. PHYSICAL EXAMINATION Aged woman who is confined to her bed by reduced strength and mobility consequent to advanced dementia and by secondary deconditioning and muscular atrophy. Not in any respiratory distress. No lateralizing neurologic signs and no features of paraplegia. Respiratory rate is not elevated. No coughing, gurgling on secretions, or wheezing. WHAT’S YOUR DIAGNOSIS? Answer on next page , Figure 1 – With the protective “bunny boots” in place, it is impossible to see either surface detail or the shape of the limb. A gauze wrapping is also in place. Brown discoloration irregularly distributed on the shins results from old venous disease. Once the protective boots (Figure 1) were removed, so that proper examination became possible, many abnormalities were seen: All the skin on this patient’s foot and ankle looks very thin and almost translucent. In consequence, the veins appear more visible than usual, although not unduly distended. Patchy discoloration on the shins represents old hemosiderin that is slowly being phagocytosed and resorbed: the delay relates to venous insufficiency. Her sole is thin and soft, reminiscent of a baby’s foot, because lack of ambulation keeps the keratin layer from ordinary thickening. The right hallux sticks up, mimicking a Babinski response although the limb has not been stimulated: this represents hallux extensus, a deformity of the great toe. This great toe appears to bend laterally, ie, shows a hallux valgus deformity. Most strikingly, the left foot seems forcefully pressed into maximal plantar flexion at the ankle joint (Figure 2). However, this is not the result of external pressure, but rather represents the rest position of the foot and ankle in this patient. Unbalanced atrophy of the flexors and extensors of the ankle has elevated the heel (drawn it proximally, toward the trunk) and depressed the forefoot (drawn it down away from the trunk). Such aberrant position constitutes a talipes equinus deformity,1  so named because the foot and ankle form a straight line with respect to the tibia, rather than a right angle, which recalls the shape of the foot and ankle of a horse. The “tali,” or ankle part (from the talus bone), requires that the forefoot rest at less than zero degrees dorsiflexion. (Diverse norms have been published; some experts measure the ankle angle with the knee in the flexed position rather than extended; others measure the ankle angle during ambulation.) Figure 2 – Viewed from the opposite side, the equinus of the left foot comes into more convincing perspective. The shape of the left great toe (hallux) mimics a swan-neck deformity. ALTERNATIVES AND MIMICS The term equinovarus may seem synonymous with talipes equinus, but equinovarus requires inversion (supination) of the foot as well, so that the sole is turned inward. In equinovarus, then, the foot is adducted, meaning that the forefoot is twisted inward.1  Such a deformity may predispose to falls even more than does the outpatient’s simple equinus. Venous disease of the lower limb is also present (see Figure 2) in our patient, and it explains the pigmentary changes. Venous and lymphatic dysfunction ought not to deform bones and joints, even though they can produce grotesque swelling and hyperkeratotic skin.2 An old stroke could not selectively injure the proximal (brain) representation of the flexors versus the extensors of the ankle joint, so that if a person had the spasticity, hyperreflexia, and Babinski residues of cerebral infarction, the foot still would not assume a “dropped” position such as is seen in our patient. When post-stroke hemiparetic patients sit, the floor tends to limit hyperextension of the ankle joint, thus reducing any minor proclivity to talipes equinus. This patient did not have diabetes. One can see a host of abnormalities in the foot and ankle in persons who do, almost entirely in the setting of combined sensory neuropathy and motor neuropathy; such conditions often lead to neuroarthropathy (the Charcot joint).3  Some cases of talipes equinus arise from diabetes (see below). Poliomyelitis is sometimes associated with an atrophic leg, but this patient has no history of polio. Her legs are symmetric, and one does not expect any specific finding in the legs in old polio, only some muscular atrophy. HOW DOES IT COME ABOUT? Multiple hypotheses are proposed, which suggests that our grasp of the pathophysiology is, in many instances, rather poor. Empirically, talipes equinus has been described in chronic wearers of high-heeled footgear. In this setting, the Achilles tendon is presumed to shorten from lack of ordinary stretching. Persons who are bedbound may lack the passive slight dorsiflexion of the ankle described in sitters, above, unless frequent enough passive range of motion exercises are performed for them, and this may account in part for the high prevalence of talipes equinus in bedbound persons, independent of the cause of their weakness. In our patient, contractures had occurred elsewhere in the body, and more in the right arm than the left (Figure 3), which reinforces the notion that there are both local and systemic factors of importance in the tendency to contractures in general and talipes equinus in particular. Contracture of the Achilles tendon is surprisingly rarely reported in relation to classic injuries and enthesopathies. WHY IN DIABETES? Diabetic feet and ankles are the subjects of numerous books.4-6  Sensory neuropathy can keep the patient from perceiving repetitive low-grade trauma, a mechanism for the formation of the neuroarthropathic joint, which— unlike so many other diseased joints—is lax rather than stiff. Perhaps such a lax joint, even in an ambulatory diabetic patient, flops when the foot is not forcibly dorsiflexed by weight bearing. This may explain, in part, the increased prevalence of talipes equinus in diabetic patients, including those who have no other recognized cause. Altered mobility of the toes, partly from interosseous atrophy in the intrinsic foot muscles as a result of diabetic denervation, may contribute. Hammertoe, to which diabetic patients are highly susceptible, represents an analogous imbalance in forces of flexion and extension, at a more distal joint in the ray (foot-to-toe) unit.1  Perhaps a tenth of diabetic persons have equinus deformities4; many have high plantar pressures. This is important because such elevated pressures constitute a key risk factor for diabetic ulcers, the disastrous consequences of which are familiar to every primary care clinician. Furthermore, sensory neuropathy underlying the one greatly increases the risk for the other. Hammertoes further alter the biomechanics and increase ulcer risk, as do callosities on the dorsa of the toes that form in reaction to hammertoes; metatarsal shearing causes aberrant pressure on the sole from the inside as well. Diabetic peripheral peroneal neuropathy can also produce just what stroke cannot: weakening of the anterior muscle group selectively, which exacerbates imbalance and thus leads to talipes equinus. WHY MAKE THE DIAGNOSIS? Talipes equinus always impairs gait, often produces pain, and predisposes to ulcerations. Extraordinary ingenuity has gone into the creation of orthoses, from the familiar ankle-foot orthosis (AFO) to orthopedic footwear. Also of great value is stretching to lengthen the gastrocnemius muscle and other manual manipulation of the ankle joint.7  The use of rocker-bottom soles has helped redistribute weight bearing for healing and prevention of pressure sores on the sole.4,5 For some afflicted persons, especially children with cerebral palsy and younger persons with traumatic lesions of the brain or spinal cord, surgical intervention may be apt. Achilles tendon lengthening has shown encouraging results; so has soleus neurotomy, when upper motor neuron lesions are responsible and spasticity is prominent.8 In our patient, surgery would be inappropriate, particularly because ambulation was lost to other factors than this deformity, and because she has no symptoms or signs of pain or discomfort from the deformity. ■ Schneiderman H, Noteroglu EH. Bilateral talipes equinus deformities in an aged bedbound demented woman. CONSULTANT. 2005;45:783-789. REFERENCES: 1. Hoppenfeld S. Physical Examination of the Spine and Extremities. Norwalk, Conn: Appleton-Century-Crofts; 1976. 2. Olofinboba K, Schneiderman H. Elephantiasis nostras. Consultant. 1995;35: 1015-1019. 3. Schneiderman H. Neuroarthropathic (Charcot’s) ankle joint in diabetic neuropathy. Consultant. 1993;33(12):65-66. 4. Lavery LA, Armstrong DG, Boulton AJ. Ankle equinus deformity and its relationship to high plantar pressure in a large population with diabetes mellitus. J Am Podiatr Med Assoc. 2002;92:479-482. 5. Van Gils CC, Roeder B. The effect of ankle equinus upon the diabetic foot. Clin Podiatr Med Surg. 2002;19:391-409, vi. 6. Caputo GM, Cavanagh PR, Ulbrecht JS, et al. Assessment and management of foot disease in patients with diabetes. N Engl J Med. 1994;331:854-860. 7. Dananberg HJ, Shearstone J, Guillano M. Manipulation method for the treatment of ankle equinus. J Am Podiatr Med Assoc. 2002;90:385-389. 8. Decq P, Filipetti P, Cubillos A, et al. Soleus neurotomy for treatment of the spastic equinus foot. Groupe d’Evaluation et de Traitement de la Spasticité et de la Dystonie. Neurosurgery. 2000;47:1154-1161. 9. Schneiderman H, Noteroglu EH. Varicella-zoster virus infection (shingles) of the maxillary division of the fifth cranial nerve, with necrosis reminiscent of zoster in HIV disease. Consultant. 2005;45:385-392.