Although anterior cruciate
ligament (ACL) injuries that require surgery are common in sports, the
continuous increase in such injuries requiring ACL reconstruction because of
leisure activities such as snowboarding or roller blading, and work related
injuries, makes it a subject of extensive research.
Rehabilitation is one of the most
important aspects of ACL reconstruction surgery but it is seen that deficits in
knee extension range pose great difficulties for rehab. Electromyographic
Biofeedback (EMG BFB) as an adjunct therapy has shown positive results but the
studies had shortcomings and required more investigations.
Biofeedback is a treatment
technique where the person learns to control certain bodily processes that
normally happen involuntarily, for example, heart rate, muscle tension, etc.
Electromyographic Biofeedback is one of the most commonly used forms of
biofeedback and it is used to measure muscle tension.
This technique was used for the
vastus medialis muscle in a controlled trial by Franz Christanell and his
colleagues as an add on therapy to investigate whether it could improve the
range of knee extension and strength after ACL reconstruction in the early
phase of the standard rehabilitation program. Vastus medialis muscle is
situated in the medial part of the thigh arising from the femur (thigh bone)
and extending into the inner border of the patella (knee cap).
The researchers recruited 16 patients,
(12 male and 4 female) aged between 20 and 49 years, from the University Clinic
of Innsbruck, Austria. All of them had undergone ACL reconstruction surgery
performed by the same surgeon and same surgical protocol. The patients were
randomized equally into control group receiving a standard rehabilitation
protocol with full postoperative weight-bearing, knee brace (0 degree
extension, 90 degree flexion), electrical stimulation, aquatics and
proprioceptive training and biofeedback group receiving the same rehab protocol
plus electromyographic biofeedback (EMG BFB) during each session for the first
six weeks. Each patient attended 16 outpatient physiotherapy sessions following
The results showed that:
EMG BFB therapy showed positive
effects on 'Symptomatic giving way' after one and two weeks. 'Symptomatic
giving way' is a term used for neuromuscular deficits of the quadriceps muscle
in the form of abrupt loss of tension during walking in the early phase of
At 6 weeks, passive knee
extension and the HHD Test (handheld dynamometer) for testing muscle strength
were significantly better in the EMG BFB group compared to controls.
Biofeedback therapy showed a
positive, but not significant, influence on flexion deficit
Thus, the results indicated the electromyographic
biofeedback therapy in the early phase of rehabilitation to be useful in
enhancing knee extension after ACL reconstruction. 'EMG BFB therapy could help
patients be more aware of correct muscle activity', say the authors.
Christanell, F., et al. The influence of
electromyographic biofeedback therapy on knee extension following anterior
cruciate ligament reconstruction: a randomized controlled trial. Sports
Medicine, Arthroscopy, Rehabilitation, Therapy & Technology 2012, 4:41