- 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.