Applying an electrical current to the quadriceps muscle may be helpful after anterior cruciate ligament (ACL) reconstructive surgery. Rehab results can be speeded up by using an electrical impulse to aid the muscle contraction. At least those are the results reported in this study from the Center for Knee and Foot Surgery Sports Traumatology Center in Heidelberg, Germany.
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 patient involved, patient compliance (cooperation), type of neuromuscular electrical stimulation applied, and intensity of the stimulation.
In this study, 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 provides 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).
The patient diaries showed that compliance was best in the rehab only (control group who did not use electrical stimulation). The information on exercise was by self-report for the exercise/rehab only group.
Patient compliance was easily verified in the two electrical stimulation groups because the stimulator devices have a data readout program. Compliance was considerably better in the Kneehab group.
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 conclude that neuromuscular electrical stimulation used along with rehab is an important training tool. When used after anterior cruciate ligament (ACL) surgery, patients obtain better results faster.
It appears that an important factor is the use of electrical stimulation early in the rehab and recovery phases following ACL reconstruction surgery. Analysis of results suggests improvements and speed of recovery are faster when strength is addressed early in the rehab timeline.
Patients in the Kneehab group returned to work a full week sooner than patients in the other two groups (control/rehab only group and Polystim neuromuscular electrical stimulation group).
What's next? The authors propose two other research ideas using neuromuscular electrical stimulation. One with other types of knee surgery such as knee replacements and another using neuromuscular electrical stimulation combined with a rehab program before knee surgery.
With the new Kneehab device, ease of application and ability to record patient compliance makes research all the more convenient. Claims that it can be used to help avoid or delay surgery must be investigated further.
Reference: Svein Feil, MA, et al. The Effectiveness of Supplementing a Standard Rehabilitation Program with a Superimposed Neuromuscular Electrical Stimulation After Anterior Cruciate Ligament Reconstruction. In The American Journal of Sports Medicine. June 2011. Vol. 39. No. 6. Pp. 1238-1247.