Determination of the Pathophysicologic Collagen Changes in the Diabetic Achilles Tendon

Diabetes is a pandemic problem with catastrophic effects on the physical, psychological, and
economic lives of patients and their families, and also places a significant burden on the
healthcare system. Changes in the integumentary system lead to plantar foot ulcerations,
which increase the risk of limb amputations and death. Specifically, limitation of ankle
joint dorsiflexion (equinus deformity) has been implicated as a major deforming force in the
development and chronicity of plantar foot ulcerations in the diabetic population. A better
mechanistic understanding of the intrinsic changes in the diabetic Achilles tendon would
assist in explaining and potentially preventing the development of chronic foot ulcerations
due to an equinus deformity.

This study will evaluate the relationship between limb loss progression and changes seen in
collagen metabolic markers in the diabetic Achilles tendon. This will be assessed by
collecting Achilles tendon samples in subjects who are at various stages of ulcer
development or limb loss and who also demonstrate an equinus deformity. All Achilles tendon
samples will be collected at the time of the Achilles lengthening procedure. There will be
five subject groups consisting of subjects who have been identified with: 1)preulcerative
plantar foot lesion 2)plantar ulceration without a history of amputation or require an
amputation 3) plantar ulceration who will be undergoing a digital amputation 4) plantar
ulceration who will be undergoing a transmetatarsal amputation or 5) plantar ulceration who
will be undergoing Chopart's or more proximal amputation. Further, systemic changes
(vasculopathy, peripheral neuropathy, nephropathy) will also be correlated with the above.
The independent variables are the following: 1) collagen metabolic markers and 2)systemic
changes. The dependent variable is limb loss progression assessed categorically (5 groups).

The 5 phases of this study include:

- Phase 1- Eligibility Assessment. Type I and Type II diabetic patients who present to
the Georgetown University Hospital Limb Salvage Center will be evaluated for inclusion
into our study based on inclusion/exclusion criteria.

- Phase 2- Interview and examination. Subjects will complete a comprehensive medical
history, physical exam, and blood work (per Standard of Care. The PI or SI will perform
an ankle joint range of motion examination and a Semmes-Weinstein 5.07 monofilament
examination (per Standard of Care. A comprehensive metabolic panel will be ordered
including hemoglobin A1C, BUN, and CR (per Standard of Care). Patients will then be
referred to the vascular surgery department for noninvasive and/or invasive vascular
studies (per standard of care) and patient will be scheduled for surgery at this time.

- Phase 3- Surgery and Tissue Collection. Surgery will be performed that may include
ulcer debridement, soft tissue or bone reconstruction, or amputation (per SOC- only
patients who have been identified as demonstrating an equinus deformity and agree to an
Achilles tendon lengthening procedure along with ulcer debridement, or soft tissue or
bone reconstruction, or amputation will be included in this study. Achilles tendon
lengthening is considered an adjunctive SOC procedure in the surgical management of the
diabetic foot). All subjects will have an Achilles tendon lengthening procedure
performed by the primary (PK) or sub-investigators (JS and CA). A tissue sample (20mg)
of the Achilles tendon will be collected at this time. This tissue will be preserved in
a dry ice container and shipped to Midwestern University for processing by the
sub-investigator (CC). The specimens will be labeled numerically with a predetermined
subject number. No patient identifying information will be on these samples.

- Phase 4- Tissue and Data Processing. Assays will be performed on the tissue samples to
measure specific metabolic markers of the diabetic Achilles tendon. Tendon collagen
concentrations will be determined via quantification of the collagen specific amino
acid, hydroxyproline by high performance liquid chromatography (HPLC) and fluorometric
detection. The extent of collagen cross-linking will be determined by measuring the
amount of pyridinium cross-link hydroxylysylpyridinoline will also be assessed though
HPLC. RT-PCR will also be performed to determine the expression of various MMPs and
TIMPs. The blood markers will be processed at Georgetown University Hospital. The
Department of Vascular Surgery at Georgetown University will perform the noninvasive
and invasive studies and the results of their findings will be reported to the
investigators.

- Phase 5-Data Analysis. The results from the physical examination, laboratory studies,
vascular studies, and tissue assays will be collected and evaluated.

Inclusion Criteria:

- Type I or Type II Diabetes - diagnosed by their primary care provider

- Demonstrates an equinus ankle deformity - Less than 0 degrees of passive dorsiflexion
at the ankle joint with the knee extended or flexed.

- Preulcerative plantar foot lesions - In the form of a callus with the epithelium
intact

OR may also have the following:

- Plantar ulceration without a history of amputations

- Plantar ulceration with a history of digital amputations - or planned digital
amputation

- Plantar ulceration with a history of transmetatarsal amputations - or planned
transmetatarsal amputation

- Plantar ulceration with a history of Chopart's or more proximal amputation - or
planned Chopart's or more proximal amputation

Exclusion Criteria:

- Does not demonstrate an equinus ankle deformity

- Cannot undergo elective surgery for any reason

- History of Achilles tendon lengthening procedure performed

- History of traumatic (acute or chronic) injury to the Achilles tendon