Botulinum Toxin Effects on Plantar Ulcer Recurrence

Not Applicable

Completed

Brief Summary: 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.

Recruitment & Eligibility

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

Arm && Interventions

Group	Intervention	Description
1	Saline	Placebo (saline) injections into 6 sites in the calf muscle
2	Botulinum Toxin	Total 200 units of Botulinum Toxin injected into 6 sites into the calf muscles.
3	Botulinum Toxin	300 units of botulinum toxin injected into 6 sites in the calf muscle

Primary Outcome Measures

Name	Time	Method
Plantar Flexor Muscle Strength	Pre-treatment, 2 weeks after injection, upon ulcer healing, 3 months and 6 months after ulcer healing	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.

Secondary Outcome Measures

Name	Time	Method
Barefoot Plantar Pressure	pre-injection, 2 weeks post injection, post healing, and 3 and 6 months post healing	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.