A Modified Neuromuscular Electrical Stimulation …

1 A Modified Neuromuscular ElectricalStimulation protocol for QuadricepsStrength Training following AnteriorCruciate ligament ReconstructionG. Kelley Fitzgerald, PT, PhD, OCS1 Sara R. Piva, PT, MS, OCS, FAAOMPT2 James J. Irrgang, PT, PhD, ATC1 Study Design:Randomized clinical trial, :To determine the effectiveness of using a Modified Neuromuscular electricalstimulation (NMES) training program as an adjunct treatment for improving quadriceps strengthand physical function in rehabilitation following anterior cruciate ligament reconstruction (ACLR).Background:NMES training for quadriceps strengthening has previously been shown to be aneffective adjunct treatment following ACLR when performed against isometric resistance using adynamometer with the knee positioned in flexion.

2 We developed a Modified version of publishedNMES protocol because some patients have difficulty tolerating the existing protocol and manyclinics may not have instrumented dynamometers. There is a need to determine the effectivenessof this Modified and Measures:Forty-three subjects who had undergone ACLR were randomly assigned toeither a group that received (NMES group) or did not receive (comparison group) the NMES treatment in conjunction with their rehabilitation. Group means for quadriceps strength andself-reported measures of knee function were compared after 12 and 16 weeks of proportion of subjects in each group achieving clinical criteria to initiate ambulation withoutcrutches, treadmill running, and agility training at selected times during rehabilitation were :The NMES group demonstrated moderately greater quadriceps strength at 12 weeks (effectsize, ), and moderately higher levels of self-reported knee function at both 12 (effect size, ) and 16 (effect size, ) weeks of rehabilitation compared to the comparison group.

3 Agreater proportion of subjects in the NMES group achieved clinical criteria for advancing to agilitytraining at 16 :The Modified NMES quadriceps training protocol can be a useful adjunct to ACLR rehabilitation programs, but the treatment effect is smaller than what has been reported inprevious Orthop Sports Phys Ther2003;33 Words:ACL, clinical trial, knee, strengthening, training1 Assistant Professor, Department of Physical Therapy, School of Health and Rehabilitation Sciences,University of Pittsburgh, Pittsburgh, Candidate, Department of Physical Therapy, School of Health and Rehabilitation Sciences,University of Pittsburgh, Pittsburgh, study was supported by grants from the Foundation for Physical Therapy Research, Inc.

4 And theUniversity of Pittsburgh Central Research and Development Fund. The study was approved by theUniversity of Pittsburgh Institutional Review Board, IRB protocol number correspondence to G. Kelley Fitzgerald, Department of Physical Therapy, University of Pittsburgh,6035 Forbes Tower, Pittsburgh, PA, 15260. E-mail: elec-tricalstimulation(NMES) has beenrecommended as anadjuncttreatmentfor strengthening the quadricepsfemoris muscle following anteriorcruciate ligament reconstruction (ACLR).4,8,13,19-21 Studies that haveshown NMES to be effective inimproving quadriceps strength fol-lowing ACLR have typically utilizeda protocol that included a 2500-Hzalternating current (AC), time-modulated to bursts of pulses ap-plied at intensities that induced atleast 50% of maximum voluntaryisometric torque.

5 A typical contrac-tion time was 10 seconds followedby 50 seconds relaxation, and eachsession induced 10 to 15 ,19,20 Subjects in these stud-ieswereseatedinachairconnected to a dynamometer withthe knee positioned in approxi-mately 60 to 85 of flexion so thatquadriceps torque could be moni-tored during the NMES results of these studies indi-cated that use of this type ofNMES protocol , combined withvoluntary exercise, yielded greatergains in quadriceps strength andfunctional ability than voluntaryexercise ,19,20492 Journal of Orthopaedic & Sports Physical TherapyRecently, we developed a Modified version ofthe published NMES protocol because some pa-tients who had undergone patellar tendon auto-graft ACLR had reported patellar donor site painduring forceful, electrically stimulated quadricepscontractions at high flexion angles.

6 Recent data fromcadaveric specimens have shown that strain on thepatella, from which the middle one-third of thepatellar tendon autograft has been harvested, in-creases with increased knee flexion angle duringisometric loading of the on thesedata, we hypothesized that performing the NMES protocol with the knee in extension might reducepatellar discomfort for these patients by reducing thestrain on the had considered continued use of the dy-namometer to set a stimulus dosage based onquadriceps torque generated during treatment, bysimply reducing the amount of knee flexion to 45 or30 . Although this would have reduced the risk ofstrain on the patella, it may have increased the riskof strain on the healing ACL ,2,10,22 Therefore,we elected to position the knee in full extensionwithout isometric resistance being applied to thedistal we no longer were using a dynamometer,we were unable to use a torque-output criterion forsetting the amplitude of the Electrical stimulus as apercent of maximum voluntary torque.

7 Therefore,our second modification was related to selecting thestimulus amplitude. We increased Stimulation ampli-tude so that at a minimum it would result in a fulltetanic contraction of the quadriceps (no fascicula-tions observed on visual inspection) with evidence ofa superior patellar glide, based on visual inspectionand palpation. We then continued to increase thestimulus amplitude to the patient s maximum toler-ance additional benefits to the modificationswe have described above are that it would allowfor an alternative treatment setup for therapistswho practice in facilities that do not have accessto a dynamometer, and treatment setup timewould be reduced as the patient would not haveto be positioned on a dynamometer prior totreatment.

8 Once Modified , the efficacy of theprotocol needed to be tested. Therefore, the pur-pose of this study was to determine the effec-tiveness of using the Modified NMES trainingprogram as an adjunct to rehabilitation followingACLR. We hypothesized that subjects receiving themodified NMES training program would demonstrategreater quadriceps strength and higher self-reportedratings of knee function compared to subjects whodid not receive the NMES training in conjunctionwith their postoperative rehabilitation 14 years of age or older who werereferred by their surgeon to our facility for rehabilita-tion following ACLR were eligible to participate assubjects in our study.

9 Subjects were excluded fromparticipation if they had undergone surgical repair ofthe meniscus or other knee ligaments concomitantwith the ACLR. Subjects were also excluded if theyhad initiated rehabilitation at another facility prior totheir first physical therapy session at our facility. Allsubjects signed a written informed consent form thatwas approved by the University of Pittsburgh Institu-tional Review Board prior to participation in subjects were enrolled in the study. Fivesubjects were eliminated from the final data of these subjects did not return to physicaltherapy for treatment shortly after enrollment in thestudy and did not respond to attempts to includethem in the testing procedures.

10 Therefore, we didnot have data for these subjects. One subject signedthe informed consent form, but before being ran-domly assigned to a treatment group, it was deter-mined that this individual had received a meniscalrepair concomitant with the ACLR and the subjectwas subsequently excluded from participation in thestudy. A total of 43 subjects completed the 1 provides a description of subject GroupsSubjects were randomly assigned to a group thateither received NMES (NMES group) or did notreceive NMES (comparison group) in conjunctionwith rehabilitation following ACLR. Subjects in bothgroups received the same basic rehabilitation pro-gram that is described below.