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Georgetown University Hospital Department of Plastic Surgery
Biomechanics of the Diabetic Foot:
Forces Encountered
Paul J Kim, DPM, MS, FACFAS
Associate ProfessorGeorgetown University School of Medicine
Director of ResearchDivision of Wound Healing & Hyperbaric Medicine
Department of Plastic Surgery
MedStar Georgetown University Hospital
The Diabetic Foot Update
San Antonio, TX
December 4-6
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Research & Consulting
Georgetown University Hospital Department of Plastic Surgery
• Nothing to disclose relevant to the lecture
• I am totally biased
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Jack of All Trades
Georgetown University Hospital Department of Plastic Surgery
Podiatry OrthopedicsPlastics
Dermatology
Infectious
DiseaseVascular
Medicine
Neurology
“We are born with two feet …and one is not a spare”-B. Kalman (Amputee)
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Soft Tissue of the Diabetic Foot
Georgetown University Hospital Center for Wound Healing
• Is different
• “diabetes” “foot” “soft tissue” “changes”= 63
indexed publications
• “diabetes” “foot” “soft tissue” “differences”= 25
indexed publications
• “diabetes” “foot” “ulcer”= 7467
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Achilles Tendon of the Diabetic Foot
Georgetown University Hospital Center for Wound Healing
• Less mobility demonstrated in joints in the hand and the feet
• Achilles tendon undergoes overall thickening with general structural disorganization
Grant WP, Sullivan R, Sonenshine DE, Adam M, Slusser JH, Carson KA, Vinik AI. Electron microscopic investigation of the effect of diabetes mellitus on the achilles tendon. J Foot Ankle Surg. 1997;36(4):272-278.
Mueller MJ, Diamond JE, Delitto A, Sinacore DR. Insensitivity, limited mobility, and plantar ulcers in patients with diabetes mellitus. Phys Ther. 1989;69(6):453-462.
Arkkila PET, Kantola IM, Viikari JSA. Limited joint mobility in type 1 diabetic patients: correlation to other diabetic
complications. J Int Med. 1994;236:215-223.
Frykberg RG, Lavery LA, Pham H, Harvey C, Harkless L, Veves A. Role of neuropathy and high foot pressures in
diabetic foot ulceration. Diab Care. 1998;21(10):1714-1719.
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Achilles Tendon of the Diabetic Foot
Georgetown University Hospital Center for Wound Healing
• Glycation induced collagen cross-linking is directly associated with the increased matrix stiffness
• The Achilles tendon of Charcot patients demonstrate decrease elasticity and a decrease tensile strength
Grant WP, Foreman EJ, Wilson AS, Jacobus DA, Kukla RM. Evaluation of young’s modulus in achilles tendons with diabetic neuroarthopathy. JAPMA;95(3):242-246.
Reddy GK. Cross-linking in collagen by nonenzymatic glycation increases the matrix stiffness in rabbit achilles tendon.
Exp Diabesity Res. 2004;5(2):143-53.Wate
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Achilles Tendon of the Diabetic Foot
Georgetown University Hospital Center for Wound Healing
• Chbinou et al (2004)
– Examined the wound healing potential of the Achilles tendon in the diabetic rat model vs. control after an acute trauma
Chbinou N, Frenette J. Insulin-dependent diabetes impairs the inflammatory response and delays
angiogenesis following achilles tendon injury. Am J Physiol Regul Integr Comp Physiol.
2004;286(5):R953-7.
Impaired inflammatory response and
angiogenesis in the diabetic rat Achilles tendon
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FORCES
Georgetown University Hospital Center for Wound Healing
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Forces
• The geometry of the diabetic foot wound
tells you what forces are at work
• 2 types of forces
– Sagittal force
– Shear force
• Transverse
• Frontal
Georgetown University Hospital Center for Wound Healing
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Forces
• Sagittal plane (Peak Plantar Forces)
– Between the foot and the shoe/ground
– Easier to measure
• Transverse/Frontal plane (Shear Forces)
– Between the underlying structures (bone) and the
plantar soft tissue structures
– Between the plantar soft tissue structures and the
shoe/ground
– Harder to measure
Georgetown University Hospital Center for Wound Healing
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Forces
Georgetown University Hospital Center for Wound Healing
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Sagittal Forces
Georgetown University Hospital Center for Wound Healing
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Sagittal Plane Forces
• Restricted ankle joint
motion(equinus)
contributes to the
development and
chronicity of diabetic foot
ulcers by increasing
plantar pressures
Georgetown University Hospital Department of Plastic Surgery
Armstrong DG, Lavery LA. Elevated peak plantar pressures in patients who have charcot arthropathy. JBJS 1998.
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Sagittal Plane Force
Georgetown University Hospital Center for Wound Healing
• Wound Shape
– Circular
• Cause– Bony deformity
– Tendon Overpowering
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Peak Plantar Pressures- DM
Georgetown University Hospital Center for Wound Healing
Lavery LA, Armstrong DG, Boulton AJM. Ankle equinus deformity and its relationship to high plantar pressure in a large
population with diabetes mellitus. JAPMA. October 2002;92(9):479-482.
Boulton AJM, Hardisty CA, Betts RP, Franks CI, Worth RC, Ward JD, Duckworth T. Dynamic foot pressure and other
studies as diagnostic and management aid in diabetic neuropathy. Diab Care.1983;6(1):26-33.
Orendurff MS, Rohr ES, Sangeorzan BJ, Weaver K, Czerniecki JM. An equinus deformity of the ankle accounts for only a
small amount of the increased forefoot plantar pressure in patients with diabetes. J Bone Joint Surg.
2006;88B(1):65-68.
Right Foot: No UlcerLeft Foot: Ulcer
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Lack of Consensus for Sagittal Plane
Measurement• Jonson SR, Gross MT: Intrexaminer reliability, interexaminer reliability, and mean values for nine lower
extremity skeletal measures in healthy naval midshipmen. J of Ortho Sports Phys Ther 25: 253, 1997.
• Clapper MP, Wolf SL: Comparison of the reliability of the orthoranger and the standard goniometer for assessing active lower extremity range of motion. Phys Ther 68: 214, 1988.
• Diamond JE, Mueller MJ, Delitto A: Reliability of a diabetic foot evaluation. Phys Ther 69: 797, 1989.
• Gheluwe BV, Kirby KA, Roosen P: Reliability and accuracy of biomechanical measurements of the lower extremities. JAPMA 92:317, 2002.
• Fosang AL, Galea MP, McCoy AT: Measures of muscle and joint performance in the lower limb of children with cerebral palsy. Dev Med Child Neuro 45: 664, 2003.
• Kilgour G, McNair P, Scott NS: Intrarater reliability of lower limb sagittal range-of-motion measures in children with spastic diplegia. Dev Med Child Neuro. 45: 391, 2003.
• Digiovanni CW, Holt S, Czerniecki J: Can the presence of equinus contracture be established by physical exam alone? J Rehab Res Dev 38: 355, 2001.
• Weaver K, Price R, Czerniecki J: Design and validation of an instrument package designed to increase the reliability of ankle range of motion measurements. J Rehab Res Dev 38: 471, 2001.
• Martin RL, McPoil TG: Reliability of ankle goniometric measurements: a literature review. JAPMA 95: 564, 2005.
• Elveru RA, Rothstein JM, Lamb RL: Goniometric reliability in a clinical setting. Phys Ther 68: 672, 1988.
• Pandya S, Florence JM, King WM, ET AL: Reliability of goniometric measurements in patients with Duchenne Muscular Dystrophy. Phys Ther 65: 1339, 1985.
• Youdas JW, Bogard CL, Suman VJ: Reliability of goniometric measurements and visual estimates of ankle joint active range of motion obtained in a clinical setting. Arch Phys Med Rehab 74: 1113, 1993.
• Wilson RW, Gieck JH, Gansneder BM: Reliability and responsiveness of disablement measures following acute ankle sprains among athletes. J Ortho Sports Phys Ther 27: 348, 1998.
Georgetown University Hospital Department of Plastic Surgery
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Sagittal Plane Force
Georgetown University Hospital Center for Wound Healing
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Georgetown University Hospital Center for Wound Healing
Circular
Wound Geometry
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Peak Sagittal Pressures
Georgetown University Hospital Center for Wound Healing
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Shear Forces
Georgetown University Hospital Center for Wound Healing
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Shear Force
Georgetown University Hospital Center for Wound Healing
• Wound Shape
–Oval, Elliptical
• Cause
–Rubbing (classic blister)• Poorly fitting shoes
• Loose dressingsWate
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Transverse Plane (Shear) Force
Georgetown University Hospital Center for Wound Healing
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Frontal Plane (Shear) Force
Georgetown University Hospital Center for Wound Healing
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Georgetown University Hospital Center for Wound Healing
Oval, Elliptical
Wound Geometry
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Practical Assessment for Shear Forces
Georgetown University Hospital Department of Plastic Surgery
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Practical Assessment for Shear Forces
Georgetown University Hospital Department of Plastic Surgery
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Shear Forces- DM PN
Georgetown University Hospital Center for Wound Healing
Lord M, Hosein R. A study of in-shoe plantar shear in patients with diabetic neuropathy. Clin Biomech. 2000;15(4):278-
83.
• 6 DM PN
patients
• Shear
measured
during
ambulation
• From 3.9-7.2
N/cm2 (highest
1st met head,
lowest 4th met
head)
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Lack of Consensus for Shear
Measurement
Georgetown University Hospital Center for Wound Healing
• Perry JE, Hall JO, Davis BL. Simultaneous measurement of plantar and shear forces in diabetic individuals.
Gait and Posture. 2002;15(1):101-107.
• Lord M, Hosein R. A study of in-shoe plantar shear in patients with diabetic neuropathy. Clin Biomech.
2000;15(4):278-83.
• Akhlaghi F, Pepper MG. In-shoe biaxial shear force measurement the Kent shear system. Med Biol Eng
Comput. 1996;34(4):315-17.
• Wang WC, LeDoux WR, Sangeorzan BJ, Reinhall PG. A shear and plantar pressure based on fiber-optic
bend loss. J Rehab Res Dev. 2005;42(3):315-26.
• Tappan JW, Pollard J, Beckett EA. Method for measuring “shearing” forces on the sole of the foot. Clin Phys
Phsyiol Meas. 1980;1(1):83-85.
• Wang WC, LeDoux WR, Sangeorzan BJ, Reinhall PG. A shear and plantar pressure based on fiber-optic
bend loss. J Rehab Res Dev. 2005;42(3):315-26.
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Sagittal & Shear Forces
Georgetown University Hospital Center for Wound Healing
Perry JE, Hall JO, Davis BL. Simultaneous measurment of plantar and shear forces in diabetic individuals. Gait and
Posture. 2002;15(1):101-107.
• 12 patients with DM and PN
• Sagittal and Shear measured during the initiation of gait
• Custom built transducer array
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Conclusions
• The foot cannot tolerate excessive,
chronic stress
• Sagittal and shear forces play a
detrimental role
• Regardless of the treatment rendered,
unless you address the forces (sagittal,
shear) the wound will not heal or will recur
or relocate
Georgetown University Hospital Center for Wound Healing
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