Effects of Non Contact Low Frequency Ultrasound in Healing Venous Leg Ulcers

The study compared the treatment effect of non-contact low frequency ultrasound in addition to standard of care versus standard of care alone in healing chronic venous leg ulcers in subjects who had documented venous stasis and reflux. Subjects that were screened and met the major inclusion criteria received standardized treatment of 30 to 40 mmHg compression, moist wound healing dressings, and debridement for a two week run-in period. If their study ulcer did not decreased by greater than 30% they were eligible for randomization. The primary endpoint was wound area reduction after four (4) weeks of study treatment. The study was performed at 22 study centers. The study included two sub-studies: fluid and tissue analysis and a wound recidivism registry that are ongoing.

Inclusion criteria

• Lower extremity full thickness venous ulcer of > 30 days duration
• Subject's wound must be between 4 cm² and 50 cm² at screening
• Documented ABI that is between 0.8 and 1.2 on the study limb or transcutaneous partial pressure oxygen (TcpO2) > 40 mmHG; or a toe pressure > 40 mmHG; or a Doppler waveform consistent with adequate flow in the foot (biphasic or triphasic waveforms) at time of screening
• Biopsy for wounds > 6 months duration
• Documented index wound etiology of venous stasis with reflux and /or incompetent valves

Exclusion criteria

• Index ulcer wound that is less than 1 cm in distance from another ulcer wound
• > 5 ulcers on the index leg
• Index ulcer wound has exposed tendons, ligaments, muscle, or bone
• Index ulcer wound presents with clinical signs of acute infection, suspected or known
• Subjects with evidence of osteomyelitis or cellulitis or gangrene in the study limb
• Subjects with amputation above a Trans Metatarsal Amputation (TMA) in the study limb
• Subjects with active malignancy on the study limb except non-melanoma skin cancer
• Index ulcer that is of arterial disease etiology
• Index ulcer of other primary etiology (ie. vasculitis, arterial, pyoderma)
• Subjects with planned vascular surgery, angioplasty or thrombolysis procedures within the study treatment phase
• Subjects with planned surgical procedure during the study treatment phase for the index wound including skin flap or skin graft
• Subjects within 6 weeks postoperatively of a vascular o skin graft procedure.
• Subject has had prior skin replacement, negative pressure therapy, or traditional ultrasound therapy applied to the index wound in the 14 days prior to screening
• Subject has had ultrasound treatment (including MIST Therapy) of the index wound.
• Subject has received growth factor therapy (e.g., autologous platelet-rich plasma gel, becaplermin, bilayered cell therapy, dermal substitute, extracellular matrix) within 14 days of screening date.
• Subject is currently receiving or has received radiation or chemotherapy within 3 months of randomization.
• Female subjects that are pregnant or refuse to utilize adequate contraceptive methods and are of childbearing age during the trial.
• Subject has one or more medical condition(s), uncontrolled diabetes (i.e. HbA1c > 12), renal, hepatic, hematologic, neurologic, or immune disease that in the opinion of the investigator would make the subject an inappropriate study candidate
• Subject's wound would require ultrasound near an electronic implant or prosthesis
• Subject is known to be suffering from a disorder or other situation that the subject or investigator feels would interfere with compliance or other study requirements
• Subject is currently enrolled or has been enrolled in the last 30 days in another investigational device or drug trial