Diabetes: Insensitive Foot Mechanisms & Management

Objectives for Learners

• Learners can describe the possible mechanisms of injury to the insensitive foot.
• Individuals can choose the physical therapy management of a patient with an insensitive foot, including footwear prescriptions and examination components, based on patient characteristics.

Diabetes and the Diabetic Foot

• In 2015, 30.3 million people in the US, which represents 9.4% of the population, had diabetes.
• By 2020, the number increased to 34.2 million, or 10.5% of the population
• Twenty-three percent of adults with diabetes are unaware they have it or did not report it.
• Foot disease and ulcers are the most common issue leading to hospitalization.
• 34% of patients with diabetes mellitus develop a foot ulcer in their lifetime.
• The annual incidence of foot ulcers in the non-diabetic population is about 2%.
• The amputation rate for individuals with diabetes is 10-13 times higher than that of controls.
• 50% of lower extremity amputations could be prevented
• 45% to 85% of non-traumatic lower extremity amputations in the US, attributable to diabetes, could have been avoided with comprehensive diabetic foot care programs, according to the CDC.

Contributing Factors to Foot Breakdown

• Peripheral arterial disease (PAD), peripheral neuropathy, & joint deformity (limited joint mobility) contributes to foot breakdown.
• Physical stresses may also cause foot breakdown, so the physical stresses need managed.
• Screening and primary treatment interventions, as well as prevention strategies for neuropathic skin breakdown, are required.

Peripheral Arterial Disease (PAD)

• PAD involves narrowed arteries caused by fatty plaque deposits, which leads to decreased circulation.
• Decreased blood supply is especially required by muscles during activity, leading to reduced oxygen supply.
• Ischemia occurs, which results in excessive lactic acid accumulation and pain.
• If PAD is more severe, it presents earlier onset in those with diabetes mellitus.
• PAD affects distal vessels and has over 4x the incidence in those with diabetes mellitus.
• For those with a 20-year duration of diabetes mellitus, 45% have PAD.

PAD Testing

• A common PAD testing method is but has poor reliability. -Assess posterior tibial and dorsalis pedis pulses, noting if they are absent or present -Relative risk = 1.90 (1.4-2.4)
• Better reliability can be achieved using an Ankle Brachial Index (ABI) or angiogram.
• The Ankle Brachial Index (ABI) is the ratio of systolic blood pressure at the ankle to the brachial systolic pressure.
• Ankle systolic blood pressure is taken using the posterior tibial artery or dorsalis pedis; blood pressure is obtained by using Doppler.
• The ABI is the gold standard for diagnosing the presence or severity of PAD with a sensitivity of 95% and a specificity of 99%.
• 0.9-1.3 is considered normal.
• Values less than .8 are problematic
• Values less than .4 may mean wound healing issues
• In those with diabetes mellitus with calcified tibial arteries, the ABI is not as effective where it can see falsely high values >1.3, a serious problem.

Angiogram

• This locates and determines the amount of occlusion from plaques in the artery- dye is injected in the artery and an x-ray determines the extent and location of the occlusion.

Other Effects of PAD

• Painful ischemic pain can occur.
• Visual changes include dry skin, thickened nails, wounds distally, poor wound healing, and rubor of dependency.

Neuropathy

• With peripheral neuropathy there is motor, sensory, and autonomic components.
• Muscular wasting of intrinsic muscles of the feet, which sensory-wise, leads to decreased touch, vibration sense, proprioception, temperature, and pain, can occur.
• Pain may be worse at night or at rest, with burning and tingling progressing to no pain.
• Peripheral neuropathy is distal and symmetric polyneuropathy.
• Stocking gloves presentation occurs, involving toes and progressing to feet and lower extremities.
• Often, no pain or subjective complaints are experienced, and after 25 years with diabetes mellitus, 50% have symptoms.
• Semmes Weinstein Monofilaments can measure peripheral neuropathy.
  • 5.07 indicates loss of protective sensation (~10 grams)
  • 4.17 is intact

  • 6.10 is essentially absent

• A predictive of ulcer/amputation occurs at 1.80-2.03 Risk Ratio.
• Patients unable to sense 5.07 SW monofilament were 10x more likely to develop foot ulcers and 17x more likely for amputation.
• Semmes Weinstein Monofilaments should be applied for 1 second on and 1 second off, applying enough pressure so the monofilament bends.
• Deficits in sweating can occur and also dry, cracking feet
• Deficits in vascular/thermoregulation can occur and fungal infections
• Lotion is a treatment that can be applied.

Mechanism of Injury

• Excessive pressures on insensitive skin can be caused by low pressures for long durations, a high pressure for short durations, and moderate pressures repeated many times.
• Paul Brand originated the physical stress theory.
• High pressure (1,300 PSI) with low duration and low pressure (5-8 PSI) with long duration (6-8 hours) can result in injury.

Role of Neuropathy and Minor Trauma

• Neuropathy + minor trauma = baseline pathology + environmental event + ulceration = faulty healing + intercurrent pathophysiology = gangrene + intercurrent pathophysiology = completed causal chain to amputation.

Foot Deformities

• Hammer toes and prominent metatarsal heads lead to high pressures and ulcers at the dorsal interphalangeal joint and plantar metatarsophalangeal joint.
• Hallux limitus of the first metatarsophalangeal joint.
• Ulcer of 1st toe
• In development of hammer toe deformity
  • Ankle dorsiflexion decreases
  • Intrinsic muscle decreases
  • Metatarsophalangeal joint flexion decreases
  • Metatarsophalangeal joint extension movement pattern increases
• Claw toes also occur

Limited Joint Mobility

• Limited joint mobility is a systematic problem
  • Multiple joint involvement affects hands, wrists, shoulders, ankles, subtalar joint, & metatarsophalangeal joints.
  • a positive prayer sign can also be seen.
• Advanced Glycated End Products accumulate
• Subtalar Joint
• Forefoot Ulcer
• Ankle Joint
• Forefoot Ulcer

Acute Charcot Arthropathy

• Neuropathic bone destruction occurs.
  • Signs: Swelling, redness, heat and sometimes pain
• Immobilization, risk for skin breakdown, risk of deformity become highly important

Developmental Stages of Charcot

• Stage 0 involves an inflammatory period with no radiographic changes, but onset of erythema, warmth, swelling, and pain occur.
• Stage 1 has fragmentation/destruction period. with fragmentation of subchondral bone & cartilage, distension of joint capsule & ligamentous laxity, joint subluxation/dislocation with deformity.
• Stage 2 goes through coalescence with diminishing inflammation; absorption of cartilaginous and subchondral debris, formation of bone callus, consolidation of fractures also occur.
• Stage 3 goes through reconstruction with bony ankylosis, hypertrophic bone formation, fixed deformity or persistent instability taking place.

Partial Foot Amputation

• Partial foot amputation can cause higher pressure on the residuum.
• More likely to develop an ulcer on residuum
• 30% develop risk for more amputation.

Extrinsic Factors: Footwear

• Poor-fitting shoes and walking barefoot with insensitive feet most commonly cause ulceration.

Patient Screening

• Check for diabetes or prediabetes history, check pulses and skin, test for neuropathy/inability to sense 5.07 monofilament

Other Factors

• HBA1c: normal range <6.5% with a current American Diabetes Association goal.
• Consulting a dietician/nutrition professional is an important factor.

Patient Examination

• Skin changes – check Autonomic Nervous System, Assess Skin Changes.
• Foot deformity: hammer toe, claw toe, prominent metatarsal heads, partial foot amputation, Charcot, bunions.
• Ulcer- blister, gangrene.
• Sensation - use monofilament - >5.07 = loss of protective sensation
  • Other sensation exams Ankle reflexes, pinprick, Tuning fork, biothesiometer.
• The ankle brachial index should be checked -pulses- posterior tibial & dorsalis pedis pulses, Check for ABI.
• Check fall history; has there been falls in the past year? do you feel unsteady standing or walking?
• Asses balance, footwear (take a look), and Functional assessment.
• With Functional assessment - Ambulation, transfers, stairs needs assessed; Quality motion at the joints foot (sit to stand).
• Check heel toe raises, Current activity level (step activity monitor), history vascular dz- claudication pain & also Check fall history.
• Assess current shoes Length, width, depth, shape, material & construction.
• Allow ½” (1.27 cm) between end of the longest toe and front of shoe.
• Look for Light color materials vs black (lower temps), Accommodating Swelling- Velcro, hook/loop closure, Linings- soft, no loose edges & Insoles- no wrinkles when assessing
• In addition assess Orthotics (semi-flexible) Also Assess:
• Materials- leather, suede, canvas or breathable synthetics (may trace their feet)
• Avoid: plastics/vinyl, sandals, high heels, open toes & thongs
• Match shoe shape to shape foot (orthotist)
• Change shoes once or twice daily.

Neuropathic Wounds

• With Decreased sebaceous gland release; sudomotor dysfunction, there is Dry skin, skin risk and skin risk is Increased callus formation & likelihood fissures; increased areas pressure & likelihood skin breakdown.
• With Loss protective sensation there is Inability to perceive harmful levels pressure/force & skin risk Increases likelihood skin and breakdown.
• With Muscle atrophy, deformity (e.g., claw toe, hammer toe) there is Increased & Motor system involved gradient; increased likelihood of skin breakdown.
• Past history of varicose veins orsurgery is venous ulcer.
• History of smoking, intermittent claudication is an arterial ulcer.
• His Numbness; Loss sensation in the foot: Common diabetes mellitus in neuropathic.

Other characteristics of wound/feet (Venous vs arterial vs Neuropathic)

• Past history of varicose veins +/- DVT, trauma, surgery to leg or multiple pregnancies (Venous), History smoking or PAINFUL leg with elevating (Arterial),His of Numbness; Loss sensation- DM. (Neuropathic).
• Between malleolus and the lower calf with Medial Mallolus (Venous), Distally & Boney promises (arterial)
• Normal ABI is (3 seconds) in Venous, Prolonged is (4-5 senconds) Artery
• Pale feet, Shiny &/or atrophy (of skin or feet), cool-weak or absent dorsalis pedis pulse = artery involved

Signs & Symptoms of feet

• Neuropathic feet: Burning, Tingling, Pins And needles, numbness, Sharp/Eletric shock, stabbing & deep achy is experienced (mostly feet & toes but also the legs) & most of the pain ↑’s with rest (& @ night, with Cramps).
• Ischemic: LE’s exhibit aching: with hanging them off the bed at night or walking. Other signs/Symptoms/Deformities:
• Palpate for the diminished, cool & usually shiny and hairless skin on ischemic feet (venous have warm, dry and palpable pulses)
• Absent sensation on “Neoropathic” feet with: Intrinsic muscle feet leading to claw toes, hammer toes &/or Prominent heads which lead to “thick/soft” calluses &/or ulcerations. What about location?
• Nero- feet ulcer is the: “Tips” of the toes & Plantar Metatarsal heads
• Ischemic foot Is mostly on the feet margin and at the tips of toes and heels

Patient examination

• Examine wounds describingEdema, Drainage, Periwound, Wound bed.
• Use Wagner scale for Staging (0) Pre- or Post lesions or cellulitis: (1) Superficial ulcer; (2)Deep ulcer; (3) Abscess or bone involvement; (4)Gangrene digits/Forefoot

Patient history

• History: check the ulcer, vascular dx, amputation, Charcot joints as you examine past dx and records
• Burning and/or numbness is symptoms of Neuropathic feet and examine them
• Claudication &/or Resting Pain is symptoms of Ischemic ft examine for non-hearing ulcer and if they hurt with palpations Diabetes, poor blood sugars can cause Kidney/eye issues to retina.
• Health Management: Manage all health problems, Dm , smoking which includes tobacco, diet- Nutrition which all involve Bone Density.

National Diabetes Education Program Risk Categories and Management Guidelines-

• Those most at risk for High Risks one being One or more from: Loss protective sensation Absent pedal pulses or Foot deformity as well a
• History of past ulcer or past amputees should especially be checked
• Those in renal end stage are at high risk.

Assessment of feet with skin breakdown

Wbat would factor In contributing pressures on ulcer? -What modifies to reduce ulcer problems.

Review all interventions in feet with complications

• What education to provide and risk for each those at risk and How toe check ft.

Pt teaching and more interventions from that teaching:

• Foot wear is important and mg can help a lot.

Ulcer mgmt and teaching to Pt’s

• Daily ft inspection from pt’s
• And footcare instructions that show safe and dry ft after cleaning.
• Avoid bare ft, avoid cutting toe nails after bathing How well should feet be cared for at home.

Shoe Fitting at home by pts and education

• Shoe width, and construction need be correct; allow 1/2” from longest tow
• The best color and shoe to were , best ways accommodate swelling and type of closures that are pt oriented
• Have smooth lining and support absorption from semi rigid support. Here list additional resources;
  • CDC Diabetes - Take Charge Your Feet
  • LEAP in feet and
  • diabetes/foot issues and teaching

Key To Preventing Pts From Ft Problems -

• The main problem Is the Pressure -So the less resistance on feet and more surface available the easier is to have good outcomes.

Ft exam:

• Is the pt protected ( Good foot - Yes that Is Mandatory to check?
• Do they have any extra needs ( good shoes / inserts. & can they be comfortable w/ those inserts.
• Medicare helps by covering costs with above guidelines. - Good shoes, (optional ) w/ support inserts.
• Also remember (as stated previously ) the risk high if there an ulcer, If there multiple problems with healing or not (special boots need with casts).

The best way to care for is:

• The right gear at all levels when need

The shoe types are:

• The more protection & less protection is needed to help (the more Hx.

-If an ulcer is present than they are consider “High Risk” and will need custom shoe with insert and bottom rocker to prevent issues

Goals to help Pt’s when using any of the above interventions

• Use best gear at all stages with Pts
• But it always more serious If they had ulceration & and will need help.

A better understanding how to help; look to goals when using proper gear

• Reduce risk factors and teach the ways from pt to pt.

• How to use it can help