Diabetes: Insensitive Feet Injury Mechanisms

• Learners learn to describe possible injury mechanisms to insensitive feet.
• Individuals chose physical therapy management for insensitive feet based on patient characteristics, including footwear prescriptions and examination components.

Diabetes and the Diabetic Foot

• In 2015, 30.3 million people were affected, which is 9.4% of US population.
• In 2020, 34.2 million were affected in US, or 10.5% of population.
• 23% of adults with diabetes don't know or report having it.
• Foot disease/ulcer is the most common problem leading to hospitalization.
• 34% of patients with diabetes mellitus (DM) develop an ulcer in their lifetime.
• The annual incidence of foot ulcers in the non-diabetic population is ~2%.
• Amputation rate is 10-13x higher than controls.
• 50% of lower extremity (LE) amputations could be prevented.
• CDC reports 45-85% of non-traumatic LE amputations in the US from diabetes could have been avoided with diabetic foot care programs.

Diabetes Incidence (CDC 2020)

• The total population estimate in 2019: 1,398,000 (1,234,000-1,562,000)
• The incidence estimates, 2018-2019 rate per 1,000(95% CI): 5.9(5.0-6.9)
• The population estimate (in thousands) for ages
• 18-44: 401 (309-493)
• 45-64: 703 (583-823)
• 65+: 293 (230-356)
• For men: 723 (604-841)
• For women: 675 (562-788)
• White, non-Hispanic: 860 (739-982)
• Black, non-Hispanic: 181 (127-235)
• Asian, non-Hispanic: 71 (36-106)
• Hispanic: 261 (173-349)

Contributing Factors to Foot Breakdown

• Peripheral Arterial Disease (PAD)
• Peripheral Neuropathy
• Joint Deformity (limited joint mobility)
• Physical stresses require physical stress management to avoid problems.
• Screening and primary treatment interventions are prevention strategies for neuropathic skin breakdown.

Peripheral Arterial Disease (PAD)

• Arteries narrowed 2nd fatty plaque deposits cause decreased circulation.
• Decreased blood supply is required by muscles esp during activity (↓ O2 supply to the muscles)
• Ischemia occurs with excessive lactic acid accumulation, causing pain.
• More severe PAD leads to earlier onset DM.
• Affects distal vessels.

• 4x incidence in DM.

• After 20-year duration of DM: 45% prevalence.

PAD Testing

• Common but poor reliability uses posterior tibial and dorsalis pedis pulse assessment, which notes pulse as either absent or present.
• Relative risk is 1.90 (1.4-2.4).
• Ankle Brachial Index (ABI) and angiogram are better reliability tests.

Ankle Brachial Index

• ABI is the ratio of systolic blood pressure at the ankle to the brachial systolic pressure.
• Ankle SBP is taken using the posterior tibial artery or dorsalis pedis.
• The blood pressure is obtained by Doppler, and the test calculates: Ankle SBP / Arm SBP.
• The gold standard for diagnosing presence or severity of PAD, ABI sensitivity is 95%, and specificity is 99%.
• Normal ABI is >0.9 to <1.3
• <.8 is problematic
• <.4 see wound healing issues
• ABI does not work well for diabetic patients with calcified tibial arteries.
• Falsely high values are >1.3, and higher values may indicate a problem.

Other Effects of PAD

• Intermittent claudication is ischemic pain.
• Causes visual changes in the skin, including dry skin, thickened nails, wounds distally, poor wound healing, and rubor of dependency.

Angiogram

• Locates and determines the quantity of occlusion from plaques in the artery.
• Dye is injected into the artery, and an x-ray determines the extent and location of the occlusion.

Neuropathy

• Peripheral neuropathy has a motor, sensory, and autonomic component.
• Muscular wasting of intrinsic muscles of feet occurs.
• Sensory effects lead to decreased touch, vibration sense, proprioception, temperature, and pain.
• Pain may be worse at night or at rest, with burning or tingling progressing to no pain.
• Distal and symmetric polyneuropathy presents in a stocking gloves pattern and involves toes, progressing to feet and LEs.
• Often no pain or subjective complaints
• After 25 years of DM, 50% have symptoms.

Measurement of Peripheral Neuropathy

• Semmes Weinstein Monofilaments
• 5.07 = loss of protective sensation (~10 grams)
• 4.17 is intact

• 6.10 = essentially absent

• The predictive value of ulcer/amputation is 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.

ANS and Skin Changes

• Deficits in sweating include dry, cracking feet.
• Deficits exist in vascular/thermoregulation, and fungal infections can develop.
• Lotion is a recommended treament.

Monofilaments

• Semmes Weinstein Monofilaments are used.
• Apply for 1 second on, followed by 1 second off.
• Apply enough pressure so the monofilament bends.

Mechanism of Injury

• Excessive pressures to insensitive skin include
• Low pressures for long duration
• High pressure for short duration
• MODERATE PRESSURES REPEATED MANY TIMES
• Dr. Paul Brand (Hanson's Disease) and physical stress theory are key concepts.

Physical Stress Theory

• Describes how increased or decreased stress levels can affect tissues, leading to cell death or injury.
• Contributing factors can include excessive stress to the plantar foot.

Role of Neuropathy and Minor Trauma

• Neuropathy and minor trauma can lead to skin lesions, ulceration, and faulty healing.
• Process involves intercurrent pathology to cause gangrene and potential amputation.
• Key factors are accumulation of component causes to form a sufficient cause and completed causal chain.

Mechanisms of Injury

• High pressure (1,300 PSI) & low duration
• Low pressure (5-8 psi) & long duration (6-8 hours)
• 40 to 70 (PSI) with moderate amounts of pressure with repeated walking.

Foot Deformities

• Hammer toes and prominent metatarsal heads are associated with high pressures and ulcers at dorsal IP and plantar MTPJ.
• Claw toes

Development of Hammer Toe Deformity

• Decreased ankle dorsiflexion.
• Decreased intrinsic muscle. Decreased MTPJ flexion.
• Increased MTPJ extension movement pattern.

Limited Joint Mobility

• A systematic problem
• Multiple joint involvement affects hands, wrist, shoulder, ankle, STJ, and MTPS.
• Positive Prayer Sign
• Advanced Glycated End Products (AGEs)
• First MTP: Hallux limitus and ulcer on 1st toe
• Subtalar Joint: Forefoot Ulcer
• Ankle Joint: Forefoot Ulcer

Acute Charcot Arthropathy

• Neuropathic bone destruction causes swelling, redness, heat, and may or may not have pain.
• Needs immobilization.
• Risk for skin breakdown and deformity.

Developmental Stages of Charcot

• Stage 0 (Inflammatory Period): response to injury, no radiographic changes, onset of erythema, warmth, swelling, pain.
• Stage 1 (Fragmentation/destruction period): fragmentation of subchondral bone and cartilage, distension of joint capsule and ligamentous laxity, joint subluxation/dislocation with deformity.
• Stage 2 (Coalescence): diminishing inflammation, absorption of cartilaginous and subchondral debris, formation of bone callus, consolidation of fractures.
• Stage 3 (Reconstruction): bony ankylosis, hypertrophic bone formation, fixed deformity or persistent instability.

Partial Foot Amputation

• Higher pressure on residuum
• More likely to develop ulcer on residuum
• 30% develop risk for more amputation
• Goal is to protect residuum from excess pressures

Extrinsic Factors - Footwear

• Poor fitting shoes and walking barefoot with insensitive feet are most common causes of ulceration. Shoes should fit comfortably.

Other Factors

• Diabetic Control requires monitoring HBA1c (normal range <6.5%) and maintaining current ADA goal of < 7.0.
• Diet/Nutrition consult.

Patient Screening

• Check for diabetes or prediabetes history
• Check for vascular disease by assessing pulse and skin changes.
• Check for neuropathy- inability to sense 5.07 monofilament.
• Assess skin changes in the autonomic nervous system (ANS).
• Check for foot deformity (hammer toe, claw toe, prominent metatarsal heads, partial foot amputation, Charcot, bunions)
• Check for ulcer, blister, and gangrene.
• Change Associated with Peripheral Neuropathy.
• Decreased sebaceous gland release; sudomotor dysfunction (decreased sweating128,132) causes dry skin.
• Loss of protective sensation causes inability to perceive harmful levels of pressure/force.
• Muscle atrophy causes deformities (e.g., claw toe, hammer toe).
• Skin Risk Involves skin risk factor.
• Increased callus formation and likelihood of fissures; increased areas of pressure and likelihood of skin breakdown due to sensory issues.
• Increased area of pressure gradient; increased likelihood of skin breakdown due to change in foot structure.

Different Types of Ulcers

• Venous ulcer - Involves history of varicose veins +/-, DVT, trauma, surgery to leg, or multiple pregnancies but also aching and swelling worse at end of day-relieved and also with leg elevation and normal capillary refilling.
• Neuropathic - Involves history of numbness, paresthesias, burning with Loss of sensation in the foot; also sites of pressure (eg, metatarsal heads, heels, toes).

Signs and Symptoms

• Nature of Neuropathic symptoms: Burning, tingling, pins and needles, numbness, sharp, electric shock, stabbing, deep aching, coldness ↑with rest, especially at night, night cramps, may be intermittent
• Ischemic Foot/ Symptoms: Rest pain: aching, burning and Intermittent claudication (IC): aching, tightening and Constant hanging LE over side of bed at night.
• Location of symptoms: toes, feet, lower legs and Posterior LE: buttock, lower leg
• Circulation : Palpable pedal pulses, little or no change with dependence Absent or diminished pedal pulses, cooler skin in the affected LE, femoral arterial bruit, venous filling time > 20 seconds, blanching skin on elevation LE with rubor on dependence

Patient Examination- History

• Requires monitoring Past History, Neuropathic symptoms, Vascular symptoms, Other diabetic complications and Health management- DM and smoking.
• Involves Ulcer wound descriptions.

Examination Tools

• Involves Wagner Scale and University of Texas- San Antonio Scale

Patient Examination

• Sensation is assessed via
• Monofilament; >5.07 = loss of protective sensation
• Others: Ankle reflexes, pinprick, 128 Hz tuning fork, biothesiometer
• Check for measure of PAD
• Functional assessment: Ambulation, transfers, stairs measuring quality of motion at the joints of foot and standing to Heel toe raises and Current activity level (step activity monitor) and If history of vascular dz- claudication pain.
• Checking Fall history: falls in past year? Do you feel unsteady? Do you ever worry about Balance? and Lastly Footwear (take a look) as well as Foot Wear depth/shape and Material

Patient Examination-Footwear and Patient Education

• Look at current shoes -BOTH FEET with Accommodate Light materials/ Velcro lining and Orthotics and Review and Recap.
• Education involves Daily Foot Inspection and Foot care; requires cutting toenails straight and wearing synthetic Wicking socks that are Moisturizing and Avoiding bare foot and shoe fitting . CDC/ NIH: NID and diabetes websites are very helpful

National Diabetes Education

• Involves annual Examination foot care; assess to Prevent

Frequency

• Involves Ulcer/ PAD and LOPS in months

Keys to feet and Catagories to good sensation

• Important to protect from pressure/force with shoes, athletic and Plantar Pressure

Footwear

Is important and should have Good fitting and if ulcer add molded insole and MET

Ulcer Management Scheme and Treatment

• Goal to include:
  • Wound Care - Off-Loading
    • Remodeling. -Protective footwear
• Impairment requires protection.
• Total Contact Casting
  • Effective offloading and heals open wounds at 90% w good BP

Sandal and Boots

• Healed wounds

High Ulcer

Requires many days and is risky

Increase Activity

Has many benefits

Surgery

Can solve any problems, but must always maintain. Requires - Toe amputation and - Transmetatarsal amputation (TMA) and - Below the knee amputation (BKA) - Above the knee amputation

Transmetatarsal Amputation Is more than 10% of diabetic patients. Heelstrike is effective

Daily Care Requires cleaning the Diabetic foot often. Requires more Key recommendations to prevent and screen.