The use of electrical stimulation has been very controversial in the last 10 years. Some studies show it is helpful. Others report no benefit. Investigators are still sorting out when electrical stimulation to enhance muscle contraction (called neuromuscular electrical stimulation or NMES) is useful and when it’s not.
Some of the differences from study to study have to do with the type of patients involved, patient compliance (cooperation), type of neuromuscular electrical stimulation applied, and intensity of the stimulation.
According to one study from the Center for Knee and Foot Surgery Sports Traumatology Center in Heidelberg, Germany, rehab results can be speeded up after knee surgery by using an electrical impulse to aid the muscle contraction.
In this particular study, electrical current to the quadriceps muscle was applied after anterior cruciate ligament (ACL) reconstructive surgery. Three groups were compared.
One group went through a standard ACL rehab program. Two other groups received standard rehab along with a neuromuscular electrical stimulation (NMES) program. There were two different types of devices used to apply the NMES: 1) conventional lead-wire Polystim and 2) a newer version called Kneehab (KH).
Polystim neuromuscular electrical stimulation is applied with four electrodes placed over the skin of the muscle. Each electrode is attached to a wire that goes to the electrical stimulation unit. The Kneehab device is a slip-on or wrap-around garment that incorporates larger electrodes into the sleeve. The Kneehab can be put on and taken off in a matter of seconds.
Neurostimulation (with both types of unit) was used three times each day on five days out of seven each week for three months. While the polystim and Kneehab units applied electrical stimulation, the patient contracted the muscle with as much force as possible.
The treatment provided a two-way reinforcement to recovering muscles. The goals of treatment were to regain strength, recover knee motion, and reduce inflammation. Hopping and running tests were used to measure results as these activities require joint function, strength, and muscular control.
The patients in all three groups were tested and retested over a period of six months. Everyone also kept a diary of their daily exercise, overall rehab program, and when they reached their goals (e.g., return to daily activities, return to work, return to sports).
Here are the key results reported: 1) performance was at its lowest for all three groups six-weeks after surgery, 2) patients using the Kneehab had the greatest strength return at that six-week marker, 3) results gradually improved after that for everyone in all three groups, 4) patients receiving neuromuscular electrical stimulation (NMES) outperformed the rehab only (control group) at every point of the study.
The authors concluded that neuromuscular electrical stimulation used along with rehab is an important training tool. When used after anterior cruciate ligament (ACL) surgery, patients obtained better results faster.