Botulinum Toxin Effects on Plantar Ulcer Recurrence

Washington University School of Medicine17 enrolled

Overview

The purpose of this grant is to collect pilot data to assess the amount of botulinum toxin that needs to be injected into the calf muscles of subjects with diabetes mellitus, peripheral neuropathy, and a plantar ulcer to decrease muscle strength. We hypothesize that a decrease in plantar flexor muscle strength will temporarily decrease plantar pressure. The decrease in plantar pressure will provide temporary protection to the new tissue as it gains tolerance to high stress with the long term potential outcome as a decrease in the ulcer recurrence rate.

Please read "Brief Summary"

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

QUADRUPLE

Enrollment

Conditions

Diabetes Mellitus Peripheral Neuropathy Plantar Ulcers

Interventions

Eligibility

Sex: ALL

Medical Language ↔ Plain English

Inclusion Criteria: * Diagnosis of diabetes mellitus and determination of diminished or absent plantar sensation * A recurrent forefoot plantar ulcer; at least the second occurrence of a plantar ulcer or a previous failure to heal a plantar ulcer with reasonable treatment intervention (Total contact casting, off loading boot, molded ankle foot orthotic, Gillette, or therapeutic footwear modifications) * Ambulatory Exclusion Criteria: * Active infection in the involved foot * Previous botulinum toxin injections * Ulcers on the dorsal surface of the foot * Ankle-brachial index \<0.45 * History of cerebral vascular accident or other neurological problems complicating their rehabilitation * Women of childbearing years unless pregnancy test is agreed upon, completed, and negative and agree to use some form of contraception during the study. * Current drug therapy that includes an anticoagulant * History of a neuromuscular disease, except peripheral neuropathy as a result of diabetes mellitus

Outcomes

Primary Outcomes

Plantar Flexor Muscle Strength

Concentric plantar flexor torque was assessed using the Biodex System 3 Pro Orthopedic Testing \& Rehabilitation dynamometer. Plantar flexor peak torque was measured at 60 deg/sec, which is comparable to the angular velocity of the ankle joint during the stance phase of walking. Three trials of each foot were completed. Peak torque was calculated as the average of the two highest torque values across trials and results were expressed as Nm. A positive value represents an increase in torque while a negative value represents a decrease in torque.

Time frame: Pre-treatment, 2 weeks after injection, upon ulcer healing, 3 months and 6 months after ulcer healing

Secondary Outcomes

Barefoot Plantar Pressure

Novel emed pressure platform was used for data collection. A two-step method of data collection was used and a minimum of two trials of each foot were recorded. The plantar pressure map was divided into 3 horizontal masks using Percent Mask software and peak plantar pressure was determined for the forefoot region. Results are expressed in N/cm\^2.

Time frame: pre-injection, 2 weeks post injection, post healing, and 3 and 6 months post healing