Vastus medialis electrical stimulation to improve lower extremity function following a lateral patellar retinacular release

A single-case study design. To examine the effect of electrical stimulation of the vastus medialis muscle on stiffness, pain and function for a patient with delayed functional progress following a lateral patellar retinacular release. Five months after an arthroscopic lateral patellar retinacular release, the patient, although highly motivated, had made little progress using routine exercises and taping. An electrical stimulation program producing approximately 300 contractions daily of the vastus medialis muscle was implemented. The electrical stimulation applied for 33 of the 36 days was a rectangular and balanced biphasic pulse of 625-micros duration, 70-Hz frequency, 8-second peak on-time, 3-second off-time, 1-second ramp-up, and 0.5-second ramp-down. Objective measures of stair climbing and hopping, together with the subjective measure of therapist-palpated superomedial patella displacement force, were recorded for each treatment visit. Other subjective measures were the patient's daily recordings of knee pain and stiffness. Patient-reported stiffness reduced rapidly as the actual and cumulative number of daily contractions of the vastus medialis muscle increased. After 8 days of electrical stimulation, the patient was able to ascend stairs unassisted and after another 21 days to hop unsupported. Stiffness rapidly reduced and function started to improve once the electrical stimulation program was implemented. Recovery during the 36 days of treatment with electrical stimulation was greater than during the previous 5 months using other methods. Compliance was not an issue, nor was muscle soreness.