Clinicals

Clinicals

Mechanisms of Vascular Disease: A Reference Book for Vascular Specialists Fitridge R, Thompson M, editors. Adelaide (AU): University of Adelaide Press; 2011. “26 Pathophysiology and Principles of Management of the Diabetic Foot” David G. Armstrong, Timothy K. Fisher, Brian Lepow, Matthew L. White, and Joseph L. Mills.

Pathophysiology of the Diabetic Foot creating an increased chance of infection. non-weight bearing. Plantar foot pressures can also be assessed with the use Neuropathy Other factors precipitating diabetic foot of a Harris ink mat or pressure sensitive Neuropathy, or the loss of protective ulcers have been identified and are listed in foot mat. sensation (LOPS) of the lower extremity, Table 26.1. is the predominant etiology for diabetic Angiopathy foot ulceration. The absence of this most Structural abnormalities/gait abnormalIn combination with the risk factors for basic nociceptive mechanism results in ities ulceration discussed above, the presence the patient’s inability to perceive local Structural deformities of the foot and of vascular occlusive disease increases foot trauma both from intrinsic factors ankle can be a potential cause of increased the risk of potential amputation. Vassuch as abnormal or faulty foot mechanpressure and subsequent ulceration. The cular disease is a common finding in ics or deformity, as well as extrinsic development of foot ulceration is often individuals with long-standing diabetes. based on a biomechanical abnormality. factors such as foreign objects or impropWhile vascular insufficiency alone is not er footwear. These factors place the foot It is important to evaluate both feet of a usually the primary cause of ulceration, at increased risk for developing an ulcer, patient for any potential problem areas. As inadequate perfusion can inhibit ulcer which can lead to amputation. described earlier, motor neuropathy can healing, leading to further tissue necrosis lead to the loss of intrinsic foot musculaand the inability to clear infection. Table Neuropathy can be subdivided into senture causing a deformity (and subsequent 26.3 provides a list of other potential risk sory, motor, and autonomic categories. overpowering of the intrinsics by the larger factors for amputation. Most cases of extrinsic muscles). Identification and vascular disease in individuals with diaSensory neuropathy typically begins management of any of the following will betes, interestingly, affect the infrapopdistally, moving proximally, and is symassist in prevention of potential ulceration: liteal vessels with relative sparing of the metrical (Something that is symmetrical hammertoe, claw toe, bunion, tailor’s bunpedal vessels. In many instances, this alhas corresponding similar parts: in other ion (bunionette), hallux limitus/rigidus, flat lows for a distal bypass to a pedal target feet, high arched feet, Charcot deformities, words, one side is the same as the other.). artery in order to increase the blood flow It is often described as a ‘stocking-glove’ or any postsurgical deformities such as to the foot (Figure 26.1). The vascular distribution. amputations. Limited joint mobility should examination is addressed in further detail also be evaluated as it can cause an inlater in this chapter. Motor neuropathy results in intrinsic crease in vertical and shear force in certain muscle wasting, causing a progressive areas, particularly to the plantar hallux, Diagnosis deformity such as hammertoe, claw toe, and lead to tissue breakdown. The Achilles History and rapid visual screening and plantar flexion deformities of the tendon should be evaluated for any type A thorough history and physical exammetatarsals. These deformities can cause of functional shortening causing equinus ination of each patient presenting with an increase in focal pressure at the areas deformity. It is common to find an increase diabetic foot pathology should include of the interphalangeal joints of the digits in glycosylation of soft tissues and tendons a history of pedal wounds, history of and beneath the metatarsal heads, respeccausing contracture of the muscles in the prior amputations, and lower extremtively, increasing the probability of ulcer posterior compartment of the leg. ity vascular interventions. physical formation. examination should note the types of This will cause an increase in plantar presdeformities present, neurological status, Autonomic neuropathy is associated with sures in the forefoot making this area more vascular status, and dermatological pathology of the sympathetic nervous prone to breakdown. presentation. The patient should be system. In the lower extremity, this instructed to remove both shoes and usually results in the absence of sweat Gait evaluation and muscle testing should socks for their examination. A systematproduction causing drying and scaling also be conducted to evaluate any poic approach should be taken in order to of the skin, increasing the likelihood of tential abnormality with ambulation and avoid missing any important aspects of cracking and fissuring. These cracks or muscle strength. Testing of the muscles in the examination. All surfaces of the foot fissures, especially in the heel, may then the lower extremity should be done both and ankle should be evaluated including serve as a portal of entry for bacteria, actively and passively, weight bearing and the nails, digits, interdigital webspac