Skeletal Muscle Atrophy and Dysfunction Following Total Knee Arthroplasty
Phase: NA
Conditions: Knee Osteoarthristis
Sponsor: University of Vermont

 
 
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Study Protocol 
 
 
Project Title: 
Version Date: 
Skeletal muscle atrophy and dysfunction following total knee  
arthroplasty 
3-23-22 
 
 
NCT number: 
NCT03051984 
 
 
Principal 
Investigator 
(contact):   
Michael J. Toth 
 
Grant Sponsor: 
NIA R01 AG050305 
 
 

 
 
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PROTOCOL SUMMARY 
 
 
Knee osteoarthritis (OA) is the leading cause of disability in older adults. Because non-surgical 
therapies are inadequate in managing symptoms and do not alter the disease course, total knee 
arthroplasty (TKA) is an important final treatment option. While TKA alleviates joint pain, objectively-
measured physical function does not improve much beyond pre-surgical levels. Moreover, it often takes 
1-2 years to recover to function to pre-surgical levels. TKA fails to correct disability, in part, because of 
the precipitous decline in lower-extremity neuromuscular function in the early, post-surgical period, 
forcing patients to first overcome the disabling effects of the procedure before redressing pre-surgery 
functional deficits. Surprisingly, very little is known about the nature of muscle structural and functional 
adaptations during the early, post-surgical period, aside from a small number of studies at the whole 
muscle level suggesting decreased neural activation as the major cause of dysfunction. To address 
these gaps in scientific knowledge and clinical treatment options early following TKA, our goals in this 
project are to: 1) to comprehensively examine, from the molecular to the whole body level, skeletal 
muscle structural and functional adaptations following TKA and 2) to assess the utility of neuromuscular 
electrical stimulation (NMES) to counter early, post-surgical muscle adaptations Based on our 
preliminary data, we hypothesize that TKA causes profound reductions in skeletal muscle size and 
intrinsic function during the early, post-surgical period that contribute to long-term functional disability 
and that these adaptations can largely be prevented by NMES. To accomplish our goals, we will study 
patients with advanced-stage knee OA prior to and 5 following surgery who are randomized to receive 
NMES or no intervention during this period. All volunteers will receive standard of care physical 
rehabilitation during this period. Tissue acquired from skeletal muscle biopsies will be used to 
characterize skeletal muscle myofilament and mitochondrial structure and function, in combination with 
assessments of whole muscle and body functional capacity. If successful, our results could shift 
conventional thinking in this field away from the role of neural adaptations as a cause of post-surgical 
disability and emphasize the importance of muscle atrophy and intrinsic myofilament function. 
Additionally, our data on the utility of NMES to prevent such adaptations may provide important 
mechanistic data to support this modality as a new transitional rehabilitative care intervention to 
improve long-term functional prognosis in TKA recipients. 
 
PURPOSE AND OBJECTIVES   
 
 
Knee OA is the leading cause of disability in older adults (1). Because non-surgical therapies are 
inadequate in managing symptoms (2) and do not alter the disease course, TKA is an important 
treatment option for knee OA. It is currently the most common elective surgery in the US (3) and its use 
will rise dramatically (~5-fold) in the future, to ~3.5 million surgeries/yr by 2030 (4) with the expansion of 
the elderly population. While TKA improves patient-reported function by alleviating joint pain (5), 
objectively-measured physical function does not improve much beyond pre-surgical levels, which is 
already severely impaired (6-8), and does not reach healthy control levels even years after surgery (8-
11). The inability of TKA to correct functional deficits consigns a large number of older adults to 
continued disability and greater risk for progression to severe disability (12-14). 
TKA fails to correct disability, in part, because of the precipitous decline in lower-extremity 
neuromuscular function in the early, post-surgical period (8, 15, 16), forcing patients to first overcome 
the disabling effects of the procedure before redressing pre-surgery functional deficits (6-8). 
Surprisingly, very little is known about the nature of muscle structural and functional adaptations during 
the early, post-surgical period, aside from a small number of studies at the whole muscle level (15, 16). 
Although informative, these studies are unable to define the mechanisms underlying reduced function 
because of the imprecision of measurements at this anatomic level and the multitude of physiological 
systems and subjective factors that impact whole muscle function. While the need for early intervention 
post-TKA to forestall its disabling effects has been consistently recognized (17, 18), there are no widely-
accepted, evidence-based interventions that target this early functional decline. We believe that lack of 
knowledge of the determinants of TKA-induced functional decline and therapeutic interventions to 
prevent or correct these maladaptations represent critical barriers to more effectively recover physical 
function in TKA recipients. 

 
 
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The proposed studies address these barriers and their successful completion would advance 
knowledge of early, post-TKA skeletal muscle adaptations at the cellular, organellar and molecular 
levels, providing a mechanistic evidence base to inform the development of preventive and rehabilitative 
interventions. As these muscle deficits contribute to long-term disability in TKA recipients (15, 19, 20), 
beneficial effects of NMES would highlight its potential as a transitional intervention to bridge a gap in 
rehabilitative care during the early, post-surgical period. Moreover, as NMES is inexpensive, FDA 
approved, portable to the clinic and home settings and there are clinicians trained in its use (PTs/OTs), 
financial, logistical and regulatory barriers for its broader application would be minimal. Finally, beneficial 
effects of NMES may argue for its broader application to other orthopedic surgical populations that 
experience post-surgical functional morbidities (21, 22), as well as other older adult populations that 
suffer muscle atrophy and dysfunction during acute disabling events (14, 23). 
Background and Hypothesis for Aim 1  
Effects of TKA on skeletal muscle structure and function. Physical function declines rapidly and 
profoundly in the early, post-surgical period following TKA (8, 24). One determinant of the TKA-related 
reduction in physical function is lower extremity muscle weakness (15, 16, 25). Data from our labs and 
others show that reductions are most prominent in the quadriceps, where strength declines >50% early, 
post-surgery (15, 25-27). Conventional wisdom holds that deficient neural activation is the primary factor 
driving muscle weakness, with a much smaller contribution from intrinsic muscle adaptations, such as 
atrophy (15). However, studies at the whole muscle level are insufficient to define muscle-specific 
adaptations because of methodological limitations (eg, whole muscle imaging techniques underestimate 
muscle atrophy compared to single fiber assessments) and confounding factors (eg, impaired neural 
activation and antagonist muscle co-contraction impair whole muscle strength measures). Regarding the 
latter, using single muscle fibers, we have shown, for the first time, profound (~30-50%) deficits in 
contractility early following TKA at the cellular level, including reductions in tension (ie, force/CSA) and 
velocity in MHC IIA and IIAX fibers. Such contractile deficits likely contribute to whole muscle/body 
functional deficits, as MHC II fibers are important determinants of dynamic muscle function (28).  
Muscle size and function are intimately related to cellular energy metabolism (29, 30). Alterations in 
mitochondrial content, structure and function that alter protein anabolism/catabolism (31, 32) and/or 
production of metabolites, such as reactive oxygen species (ROS), have been shown to promote 
atrophy and contractile dysfunction (33-36). Stimuli present in the perioperative and early, post-surgical 
period, such as inflammation, hypoxia and muscle disuse, can provoke mitochondrial loss and 
dysfunction and, in turn, muscle atrophy and weakness (35, 37, 38). Thus, mitochondria may serve to 
both sense these stimuli and transduce their signal throughout the cell. In this context, the early, post-
TKA period is characterized by detrimental mitochondrial adaptations that may not only impair energy 
provision to support physical function (39, 40), but may contribute to muscle atrophy and dysfunction 
(33, 38, 41). Collectively, available literature and our preliminary data in TKA recipients suggest that it is 
reasonable to hypothesize that: TKA will reduce single skeletal muscle fiber size and contractility and 
mitochondrial content and function, while increasing mitochondrial ROS generation. 
Background and Hypothesis for Aim 2  
Effects of NMES on skeletal muscle structure and function following TKA. During the early, post-
surgical period, rehabilitation of TKA recipients is impeded by pain, healing of the surgical site and 
limited range of motion. Because of these impediments, more anabolic/strengthening exercises are not 
started until several weeks post-surgery. NMES has been forwarded as an adjunct to classical resistive-
type exercises begun at this later date to overcome neural activation deficits to allow activation of a 
greater quantity of muscle mass (42). A recent trial, which has been the largest to date using NMES in 
TKA recipients, showed that NMES as an adjunct to resistance training, with both starting at 4 weeks 
post-surgery, had no additional benefit over resistance training alone (43), a result confirmed in other 
orthopedic surgical populations (44). In stark contrast to these results, use of NMES alone early, post-
TKA improves physical function (45). In fact, work from our labs showed that NMES begun 48 hrs post-
surgery and maintained for 6 wks reduced quadriceps strength loss and lessened reductions in physical 
function (46). The timing of the start of the NMES intervention is critical because, although we 
acknowledge that use of NMES in orthopedic populations is not new, its use early post-surgery is. More 
specifically, NMES use early post-surgery to counter skeletal muscle atrophy and intrinsic dysfunction 

 
 
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may offer a promising transitional intervention to bridge the gap in rehabilitation care and improve long-
term muscle functionality.  
For NMES to improve disability in TKA recipients, it should address the mechanisms underlying 
persistent functional deficits. While impaired neural activation is widely believed to drive early, post-
surgical reductions in muscle strength (15), these deficits regress rapidly, with near complete correction 
within 3-6 months (46). In contrast, intrinsic muscle adaptations are thought to remediate more slowly, 
contributing disproportionately to long-term functional deficits (15, 19, 20). Thus, while NMES may 
improve early functional deficits due to impaired neural activation (47, 48), as our data show (46), to 
impact long-term disability it needs to prevent atrophy and intrinsic contractile dysfunction during the 
early, post-surgical period. To this end, our preliminary data provide the first direct evidence of effects of 
NMES on muscle fiber size and function in TKA recipients. We found that early use of NMES diminishes 
fiber atrophy in MHC I and II fibers and improves myofilament protein function in MHC II fibers, with a 
surprising improvement in contractile velocity (+23%) after 5 wks. The combined effect of improved 
tension and velocity may mitigate reductions in whole muscle power output (power= force X velocity) 
that predispose to disability (49). These effects of NMES on single muscle fiber size and MHC II fiber 
function, particularly improvements in contractile velocity, which are increasingly thought to be at the 
root of deficits in muscle power that promote disability (50), may ameliorate the precipitous decline in 
lower extremity function in the early post-surgical period following TKA.  
How does NMES preserve muscle size and function? As NMES maintains neuromuscular activation 
in the face of post-operative muscle disuse, it likely functions similar to standard exercise, which 
maintains myocellular size and function during catabolic conditions (51, 52). Several pathways 
stimulated by exercise influence muscle size/function, in part, by preserving mitochondrial content and 
function (53-58). In support of this notion, we found that NMES not only preserved skeletal muscle IMF 
mitochondria, but dramatically increased their content. In addition to these structural effects, NMES 
nearly prevented TKA-induced reductions in ADP-stimulated, oxygen consumption rate in isolated 
mitochondra. These effects of NMES on mitochondrial biology may partially explain its ability to mitigate 
muscle atrophy, in accord with genetic and pharmacological interventions in pre-clincial models that 
seek to preserve mitochondrial content and funciton and have been shown to prevent atrophy (33, 35, 
59, 60). To our knowledge, however, this hypothesis has never been evaluated in humans, much less 
over time in response to a clinical events that predipose to disability progression in older adults (14, 23). 
Collectively, our preliminary data describing the effects of early NMES use following TKA on 
myofilament and mitochondrial content and function suggest that it is reasonable to hypothesize that: 
NMES will diminish TKA-induced single muscle fiber atrophy, declines in contractile and mitochondrial 
function and increases in ROS production, while increasing mitochondrial content. 
 
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Objectives:   
Our goals in this application are two-fold: 1) to comprehensively examine, from the molecular to the 
whole body level, skeletal muscle structural and functional adaptations following TKA to identify factors 
contributing to functional disability and 2) to assess the utility of neuromuscular electrical stimulation 
(NMES) to counter early, post-surgical muscle adaptations and improve muscle size and functionality at 
these same anatomic levels. Our rationale is that the early post-surgical period is critical for 
development of skeletal muscle structural and functional adaptations that contribute to disability in TKA 
recipients and that preventive/rehabilitative interventions that specifically target these muscle 
adaptations are needed to improve long-term functional recovery. Based on our preliminary data, we 
hypothesize that TKA causes profound reductions in skeletal muscle size and intrinsic function during 
the early, post-surgical period that contribute to functional disability and that these adaptations can 
largely be prevented by NMES. We propose two aims to test our hypothetical model: 
Aim 1: Define the effects of TKA on skeletal muscle myofilament and mitochondrial structure 
and function during the early, post-surgical period from molecular to the whole body level. 

 
 
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Hypothesis: TKA will impair whole body and muscle function, in part, through reductions in skeletal 
muscle fiber size, with preferential atrophy in MHC II sub-types, reduced single fiber tension 
(force/CSA) and velocity and decreased mitochondrial content and function. 
Aim 2: Define the utility of NMES to prevent early, postsurgical skeletal muscle structural and 
functional adaptations to TKA. 
Hypothesis: NMES will lessen TKA-induced muscle fiber atrophy and contractile dysfunction and 
preserve or increase mitochondrial content and respiration while lessening mitochondrial ROS 
production. 
 
METHODS AND PROCEDURES  
 
We will use a randomized, controlled design, in which older adult patients with knee OA being 
evaluated for TKA will be recruited and undergo baseline evaluations (Pre-surgery Testing) prior to 
surgery. Patients will then be randomized (1:1) to a 5 week intervention of NMES or control 
(n=32/group, expecting 25% attrition rate to arrive at n=24/group) using a covariate-adaptive approach, 
which will incorporate age, BMI, sex and surgeon into the randomization scheme. After completing the 
intervention, they will be re-tested at 5 weeks (5 wk Post-surgery Testing) following surgery. Volunteers 
can opt into an optional 2 week follow-up testing period. Primary outcomes will be tested at the 5 week 
evaluation, with 2 wk testing including assessment of ancillary mechanistic hypotheses. Assessment of 
physical activity by accelerometry (5 d each throughout the 5 week post-surgical period) will monitor 
variation in physical activity between groups. Each phase of the protocol is described below. 
Pre-surgery testing will include assessments of whole muscle size and function, accelerometry to 
assess habitual weight-bearing activity level, single muscle fiber size and mechanical function and 
mitochondrial content and function. Detailed descriptions of these assessments are provided below. 
Treatment intervention Volunteers will be randomized to NMES or control groups for the 5 weeks 
following TKA surgery (described below in detail).  
5 wk Post-surgery testing will include measurements identical to Baseline Testing, with post-training 
biopsies performed ≥3 d following strength testing/NMES to eliminate any residual effects, per our 
usual protocol in our past IRB-approved training studies in other clinical populations (heart failure, end-
stage knee osteoarthritis). 
2 wk Post-surgery testing (optional) will consist of a skeletal muscle biopsy to assess single muscle 
fiber size, mitochondrial content and function and anabolic catabolic signaling pathways via standard 
biochemical/immunolabeling techniques. 
6 month Post-surgery testing will include assessments of whole muscle size and function and whole 
body functional measures to provide data on whether hypothesized preservation in single muscle fiber 
size/function with NMES will relate to longer-term improvements in whole muscle size/function and 
whole body functionality.  
Procedures:   
 
All of the procedures and interventions on volunteers recruited for these studies are carried out solely for 
research purposes, as none are part of standard therapy in TKA patients. We will describe procedures 
that will be performed for each of the Aims. 
Aim 1 
Primary outcomes, which will be assessed at baseline and 5 wk post-intervention, include: skeletal 
muscle fiber cross-sectional area (CSA) and function, mitochondrial content, morphology and function 
and weight-bearing activity. Secondary outcomes include: whole muscle size/function and 
accelerometry. Procedures that will be performed on volunteers to obtain these primary and secondary 
outcome measures are described below. 

 
 
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Pre-surgery testing 
Percutaneous skeletal muscle biopsy of the vastus lateralis (VL) will be performed on the leg 
scheduled to undergo TKA, per procedures used by our research group in a range of patient 
populations, including knee OA patients (1, 2). Tissue will be proportioned for mechanical (single fiber 
function), immunohistochemical (IHC), mitochondrial functional (oxygen consumption rate and hydrogen 
peroxide production) and electron microscopy (EM) measurements, with remaining tissue frozen in 
liquid N2. The VL was chosen because of its importance in determining functional disability (3) and its 
structural and functional adaptations to TKA (4). The following measures will be assessed from muscle 
tissue. 
Single fiber function will be assessed on segments of chemically-skinned muscle fibers, as used 
routinely by our lab. Cellular function will be measured on chemically-skinned, fiber segments, 
including force, velocity and power, as described by us (1) and molecular function (myosin-actin 
cross-bridge kinetics/mechanics) by sinusoidal analysis, as pioneered in human skeletal muscle by 
our lab (5). These measures will be available on the most abundant fiber types: MHC I, IIA and IIAX 
(>90% of fibers in cancer patients (6)).  
Single fiber cross-sectional area (CSA) will be measured by IHC, as described (1), with the 
addition of MHC IIA and IIX antibodies to delineate MHC II sub-types, as described (7), as these 
comprise the majority of fibers (MHC I, IIA, IIAX; >90%) in cancer patients (2).  
Mitochondrial content/morphology (sub-sarcolemmal and intermyofibrillar: % content, size, # per 
unit area/sarcolemmal length) and myofibrillar ultrastructure (myofibrillar % area, A-band length) will 
also be assessed by EM, as described by us (2, 6). 
Accelerometry will be performed (5 d each): at baseline and ~weekly throughout the 5 week 
intervention, as described (12). This will be accomplished using an Actigraph waist-worn accelerometer.  
Thigh muscle size and body composition will be measured, as described (13), to track changes in 
body composition and quadriceps muscle CSA by CT to characterize differential changes between legs, 
as described (2). 
Thigh muscle function will be assessed by isokinetic/isometric dynamometry, as described (12), to 
characterize changes in whole muscle function (isometric: 70°; isokinetic: 60 and 180 °/sec), adjusted 
for quadriceps CSA, with central neural activation assessed by the interpolation technique, as described 
by us (14). 
Whole body function will be assessed using the 30 second sit-to-stand test, timed up and go (TUG), 
stair climb (SCT) (16) and the Short Physical Performance Battery (SPPB) (17, 18), as described by us 
(19, 20).  
Blood samples will be taken to examine circulating factors that may contribute to muscle atrophy 
and/or dysfunction. 
Questionnaires will consist of the Western Ontario and McMaster Universities Arthritis Index 
(WOMAC) and Medical Outcomes Short Form (SF-36; Appendix 1) form to assess the symptom severity 
of the volunteer’s knee OA, as well as their functional status and quality of life to be used as basic data 
to characterize the cohort so that, upon publication, readers can assess the external validity of our 
cohort. 
NMES 
NMES will be conducted on the quadriceps of the operative leg using a portable stimulation device 
(Empi Continuum; DJO Global), starting within 48-72 hrs of surgery, as described by us (21), and used 
in our preliminary studies at UVM (CHRMS 12-184). Briefly, the operative leg will be immobilized on a 
support board at a neutral angle (30º) or using a knee positioning bolster and ankle weight, with 
electrodes affixed to the anterior surface of the thigh. Symmetrical, biphasic pulses (400 µs duration at 
50 Hz) will be used, with a duty cycle of 25% (10 s on, 30 s off), with patient-selected stimulation 
intensity to cause visible contractions below pain threshold. NMES sessions will occur 5 d/week, twice 
daily for 45 min (5 min warm-up) for 5 wks. Our prior trial (21) had excellent compliance, with 91 ± 2% of 
sessions completed at 5 weeks post-TKA, with compliance not related to age (P>0.5) or number of 
comorbidities (P>0.5). Studies utilizing muscle biopsies have yielded a similarly high compliance with 

 
 
9 of 15 
NMES (93 ±4%). Thus, we have assumed an attrition rate of 10% due to non-compliance. To track the 
NMES dose, volunteers will self-report device intensity (mA), as well as knee pain (see Appendix 2), 
with reports reviewed weekly by the study coordinator. Compliance will be confirmed using the 
compliance monitoring feature built-in to the device software and we will measure NMES dose (% pre-
surgery MVIC) directly at 5 weeks post-TKA, as described (22).  
Control 
Volunteers randomized to the control group will not receive an NMES device and will be instructed to 
not undertake any structured exercise regimen outside of standard post-TKA rehabilitation. Controls will 
receive weekly phone calls to check on their rehabilitation and to standardize interaction with study 
personnel to the NMES group and will record knee pain similar to volunteers in the NMES group. We 
chose not to utilize a sham control NMES intervention (eg, electrical stimulation below the threshold to 
elicit muscle contraction) to mitigate the possibility that patients will increase stimulation intensities 
sufficient to produce muscle contractions if there is perceived benefit. Rigorous control over who 
receives NMES was considered preferable to controlling for any effects of sub-threshold, cutaneous 
electrical stimulation. 
5 week Post-surgery testing will be identical to pre-surgery testing, as described above. The only 
addition to the pre-surgery regimen will be the use of NMES during strength testing in order to assess 
the intensity of muscle contraction elicited by the NMES stimulus, as described by us (22). Post-training 
muscle biopsies will be performed ≥3 following strength testing or the last bout of training to eliminate 
any residual effects, as described by us (23).  
6 month Post-surgery testing will include whole muscle strength testing, body composition analysis and 
whole body functional assessments. The purpose of these assessments is not to assess whether NMES 
is effective at improving longer-term functional recovery, as our co-I’s research has demonstrated (21), 
but instead to determine whether the effects of NMES to mitigate muscle atrophy and dysfunction during 
the early, post-surgical period predicts longer-term improvements in function. 
2 week Post-surgery testing will be optional. Volunteers can opt in/out of testing at this time point. The 
primary purpose of testing at 2 weeks post-surgery is to obtain data at a mid-point between surgery and 
the 5 week time point to better define potential mechanisms contributing to muscle atrophy and 
contractile dysfunction. As with 5 week post-surgery testing, the contractile response to the NMES 
stimulus will be assessed during strength testing. The only omission will be contractile function 
measurements on single muscle fibers.  
References cited above: 
 
1. 
Callahan, D. M., Miller, M. S., Sweeny, A. P., Tourville, T. W., Slauterbeck, J. R., Savage, P. D., Maughan, D. W., 
Ades, P. A., Beynnon, B. D., and Toth, M. J. (2014) Muscle disuse alters skeletal muscle contractile function at the 
molecular and cellular levels in older adult humans in a sex-specific manner. J Physiol 592, 4555-4573 
2. 
Callahan, D. M., Tourville, T. W., Miller, M. S., Hackett, S. B., Sharma, H., Cruickshank, N. C., Slauterbeck, J. R., 
Savage, P. D., Ades, P. A., Maughan, D. W., Beynnon, B. D., and Toth, M. J. (2015) Chronic disuse and skeletal 
muscle structure in older adults: sex-specific differences and relationships to contractile function. Am J Physiol Cell 
Physiol 308, C932-C943 
3. 
Bean, J. F., Kiely, D. K., LaRose, S., and Leveille, S. G. (2008) Which impairments are most associated with high 
mobility performance in older adults? Implications for a rehabilitation prescription. Arch Phys Med Rehabil 89, 2278-
2284 
4. 
Judd, D. L., Eckhoff, D. G., and Stevens-Lapsley, J. E. (2012) Muscle strength loss in the lower limb after total knee 
arthroplasty. Am J Phys Med Rehabil 91, 220-230 
5. 
Miller, M. S., VanBuren, P., LeWinter, M. M., Braddock, J. M., Ades, P. A., Maughan, D. W., Palmer, B. M., and Toth, 
M. J. (2010) Chronic heart failure decreases cross-bridge kinetics in single skeletal muscle fibers from humans. J 
Physiol 588, 4039-4053 
6. 
Toth, M. J., Miller, M. S., Callahan, D. M., Sweeny, A. P., Nunez, I., Grunberg, S. M., Der-Torossian, H., Couch, M. E., 
and Dittus, K. (2013) Molecular mechanisms underlying skeletal muscle weakness in human cancer: reduced myosin-
actin cross-bridge formation and kinetics. J Appl Physiol 114, 858-868 
7. 
Fry, C. S., Noehren, B., Mula, J., Ubele, M. F., Westgate, P. M., Kern, P. A., and Peterson, C. A. (2014) Fibre type-
specific satellite cell response to aerobic training in sedentary adults. J Physiol 592, 2625-2635 
8. 
Lanza, I. R., and Nair, K. S. (2009) Chapter 20: Functional Assessment of Isolated Mitochondria In Vitro. In Methods in 
Enzymology (William, S. A., and Anne, N. M., eds) Vol. 457 pp. 349-372, Academic Press 
9. 
Rogers, G. W., Brand, M. D., Petrosyan, S., Ashok, D., Elorza, A. A., Ferrick, D. A., and Murphy, A. N. (2011) High 
throughput microplate respiratory measurements using minimal quantities of isolated mitochondria. PLoS ONE 6, 
e21746 
10. 
Zhou, M., Diwu, Z., Panchuk-Voloshina, N., and Haugland, R. P. (1997) A stable nonfluorescent derivative of resorufin 

 
 
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for the fluorometric determination of trace hydrogen peroxide: applications in detecting the activity of phagocyte 
NADPH oxidase and other oxidases. Anal Biochem 253, 162-168 
11. 
Starkov, A. (2010) Measurement of mitochondrial ROS production. In Protein Misfolding and Cellular Stress in 
Disease and Aging (Bross, P., and Gregersen, N., eds) Vol. 648 pp. 245-255, Humana Press 
12. 
Toth, M. J., Shaw, A. O., Miller, M. S., VanBuren, P., LeWinter, M. M., Maughan, D., and Ades, P. A. (2010) Reduced 
knee extensor function in heart failure is not explained by inactivity. Int J Cardiol 143, 276-282 
13. 
Miller, M. S., VanBuren, P., LeWinter, M. M., Lecker, S. H., Selby, D. E., Palmer, B. M., Maughan, D. W., Ades, P. A., 
and Toth, M. J. (2009) Mechanisms underlying skeletal muscle weakness in human heart failure: alterations in single 
fiber myosin protein content and function. Circ Heart Fail 2, 700-706 
14. 
Thomas, A. C., and Stevens-Lapsley, J. E. (2012) Importance of attenuating quadriceps activation deficits after total 
knee arthroplasty. Exerc Sport Sci Rev 40, 95-101 
15. 
Podsialdo, D., and Richardson, S. (1991) The timed "Up and Go": a test of basic functional mobility for frail elderly 
persons. J Am Geriatr Soc 39, 142-148 
16. 
Almeida, G. J., Schroeder, C. A., Gil, A. B., Fitzgerald, G. K., and Piva, S. R. (2010) Interrater reliability and validity of 
the stair ascend/descend test in subjects with total knee arthroplasty. Arch Phys Med Rehabil 91, 932-938 
17. 
Guralnik, J. M., Simonsick, E. M., Ferrucci, L., Glynn, R. J., Berkman, L. F., Blazer, D. G., Scherr, P. A., and Wallace, 
R. B. (1994) A short physical performance battery assessing lower extremity function: association with self-reported 
disability and prediction of mortality and nursing home admission. J Gerontol A Biol Sci Med Sci 49, M85-M94 
18. 
Onder, G., Penninx, B. W. J. H., Ferrucci, L., Fried, L. P., Guralnik, J. M., and Pahor, M. (2005) Measures of physical 
performance and risk for progressive and catastrophic disability: results from the Women's Health and Aging Study. J 
Gerontol A Biol Sci Med Sci 60, 74-79 
19. 
Bade, M. J., Kohrt, W. M., and Stevens-Lapsley, J. E. (2010) Outcomes before and after total knee arthroplasty 
compared to healthy adults. J Orthop Sports Phys Therp 40, 559-567 
20. 
Savage, P. D., Shaw, A. O., Miller, M. S., VanBuren, P., LeWinter, M. M., Ades, P. A., and Toth, M. J. (2011) Effect of 
resistance training on physical disability in chronic heart failure. Med Sci Sports Exer 43, 1379-1386 
21. 
Stevens-Lapsley, J. E., Balter, J. E., Wolfe, P., Eckhoff, D. G., and Kohrt, W. M. (2012) Early neuromuscular electrical 
stimulation to improve quadriceps muscle strength after total knee arthroplasty: a randomized controlled trial. Phys 
Ther 92, 210-226 
22. 
Stevens-Lapsley, J. E., Balter, J. E., Wolfe, P., Eckhoff, D. G., Schwartz, R. S., Schenkman, M., and Kohrt, W. M. 
(2012) Relationship between intensity of quadriceps muscle neuromuscular electrical stimulation and strength 
recovery after total knee arthroplasty. Phys Ther 92, 1187-1196 
23. 
Toth, M. J., Miller, M. S., VanBuren, P., Bedrin, N. G., LeWinter, M. M., Ades, P. A., and Palmer, B. M. (2012) 
Resistance training alters skeletal muscle structure and function in human heart failure: effects at the tissue, cellular 
and molecular levels. J Physiol 590, 1243-1259 
 
 
SUBJECT CHARACTERISTICS, IDENTIFICATION AND RECRUITMENT  
 
A single cohort of patients with knee OA will be recruited and tested prior to and following TKA to 
address both aims. We chose to study TKA recipients for a number of reasons. First, the primary 
antecedent morbidity leading to TKA, knee OA, is the leading cause of disability in older adults (1), 
making TKA recipients an important segment of the older adult disabled population. Second, because of 
its elective nature, TKA is unique among disabling clinical events in permitting pre- and post-surgical 
assessments. Although other orthopedic trauma/surgeries (eg, hip fracture) may provoke greater 
functional disability (2), their emergent nature and complex clinical background/course (eg, blunt force 
trauma, other fractures, etc) make them extremely difficult to study, with no pre-injury/pre-op testing 
possible, and would introduce numerous confounders. Moreover, TKA is profoundly disabling, as we 
have shown (3), making it a useful clinical condition in which to study muscle adaptations and 
remediative interventions. Finally, we chose primary knee OA patients because they comprise the 
majority of TKA recipients (4) and because antecedent pathologies for secondary knee OA (eg, 
rheumatoid arthritis) could confound the response to TKA/NMES (5).  
We chose 2 and 5 weeks for the post-TKA assessments. Broadly speaking, we chose to study the 1st 
5 wk post-TKA because this represents an important gap in rehabilitative care, as detailed above in the 
Purpose and Objectives section. Moreover, large structural and functional skeletal muscle changes 
occur, making it an optimal time to intervene with preventive modalities, such as NMES. The 2 wk time 
point was chosen in response to reviewer’s requests for evaluation of additional potential mechanisms 
underlying atrophy and contractile dysfunction because this is the absolute closest point to the TKA 
surgery that our surgeons would allow muscle biopsies to be performed because patients are typically 
on anti-coagulant therapy for the first ~7-10 d post-TKA, a contraindication for muscle biopsy. The fact 
that our preliminary data suggests that atrophy is continual throughout the 5 wk time period argues that 
mechanisms contributing to atrophy and dysfunction are likely operative at the 2 wk time point.  
We chose to focus on knee extensors because we and others have shown that they experience the 

 
 
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greatest functional decline (-42 to -60%;(6, 7)), 2- to ~3-fold greater than dorsi/plantarflexors (6), with 
atrophy of comparable magnitude to functional deficits. Moreover, the greatest functional declines occur 
in activities of daily living (ADL) with strong reliance on the extensor mechanism (eg, SCT, TUG; (3)), 
making knee extensor function an important determinant of TKA-related disability. Knowledge of the 
adaptations to TKA in all lower extremity muscles, as well as their response to NMES, is needed, but in 
lieu of practical limitations in studying this population (eg, # of muscles studied/biopsied) and available 
technologies for NMES, we have focused on the knee extensors because of their profound impact on 
physical function. 
Literature cited: 
 
1. 
Anonymous. (2009) Prevalence and most common causes of disability among adults--United States, 2005. MMWR 
Morbid Mortal Week Rep 58, 421-426 
2. 
Portegijs, E., Sipila, S., Rantanen, T., and Lamb, S. E. (2008) Leg extension power deficit and mobility limitation in 
women recovering from hip fracture. Am J Phys Med Rehabil 87, 363-370 
3. 
Stevens-Lapsley, J. E., Balter, J. E., Wolfe, P., Eckhoff, D. G., and Kohrt, W. M. (2012) Early neuromuscular electrical 
stimulation to improve quadriceps muscle strength after total knee arthroplasty: a randomized controlled trial. Phys 
Ther 92, 210-226 
4. 
Lawrence, R. C., Felson, D. T., Helmick, C. G., Arnold, L. M., Choi, H., Deyo, R. A., Gabriel, S., Hirsch, R., Hochberg, 
M. C., Hunder, G. G., Jordan, J. M., Katz, J. N., Kremers, H. M., Wolfe, F., and National Arthritis Data, W. (2008) 
Estimates of the prevalence of arthritis and other rheumatic conditions in the United States: Part II. Arthritis Rheum 58, 
26-35 
5. 
Beenakker, K. G. M., Ling, C. H., Meskers, C. G. M., de Craen, A. J. M., Stijnen, T., Westendorp, R. G. J., and Maier, 
A. B. (2010) Patterns of muscle strength loss with age in the general population and patients with a chronic 
inflammatory state. Ageing Res Rev 9, 431-436 
6. 
Judd, D. L., Eckhoff, D. G., and Stevens-Lapsley, J. E. (2012) Muscle strength loss in the lower limb after total knee 
arthroplasty. Am J Phys Med Rehabil 91, 220-230 
7. 
Petterson, S. C., Barrance, P., Buchanan, T., Binder-Macleod, S., and Snyder-Mackler, L. (2008) Mechanisms 
underlying quadriceps weakness in knee osteoarthritis. Med Sci Sports Exerc 40, 422-427 
 
 
Inclusion/Exclusion Criteria: 
Patients (50-75 yrs) with symptomatic, primary knee OA being evaluated for TKA will be recruited. 
Exclusion criteria include: 1) knee OA secondary to inflammatory/autoimmune disease; 2) 
untreated/uncontrolled hypertension, diabetes or thyroid disease; 3) chronic heart failure, actively-
treated malignancy, exercise-limiting peripheral vascular disease, stroke or neuromuscular disease; or 
4) body mass index >38 kg/m2. Note that many of these exclusions are contraindications for TKA (eg, 
untreated hypertension/diabetes, actively treated malignancy). Thus, such patients would not be part of 
the pool of prospective patients, and we cite them for completeness to show that we are excluding 
potentially confounding comorbidities for muscle size and function. Finally, we will exclude patients with 
a lower extremity blood clot, known coagulopathies or an implanted pacemaker/ICD, contraindications 
for NMES and the muscle biopsy, as detailed above. These inclusion/exclusion criteria are similar to 
those used to generate our preliminary data. Of the ~300 TKAs/yr that meet initial procedural eligibility 
at our center, 53% (n=159/yr or 636 for 4 yrs of recruitment) would meet the above inclusion/exclusion 
criteria, suggesting a more than adequate patient base.  
Recruitment:   
Research coordinator, who is an UVMMC employee in the Dept of Medicine, will screen surgical 
schedule for physicians in the Dept of Orthopaedics and Rehabilitation for patients that meet basic 
procedural eligibility (receiving a unilateral total knee arthroplasty procedure) and eligibility criteria (age, 
BMI, absence of exclusionary comorbid conditions, etc) to identify prospective participants. The 
coordinator will notify care providers in the Dept of Orthopedics and Rehabilitation of potentially eligible 
patients. An Ortho care provider will notify the patient that they may qualify for a research study and 
provide the patient with an IRB-approved trifold information pamphlet or provide a brief verbal summary 
of the study if contact is made by phone. The care provider will ask the patient if they would like to 
receive more information from research study staff. 
 
 
 

 
 
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Risks/Benefits:   
Potential risks: Below we have highlighted those procedures/measurements that have anything greater 
than negligible risk to the volunteers’ health for each phase of the study.  
Pre-surgery and 2 and 5 week Post-surgery Testing: Risks associated with the muscle biopsy 
procedure include excessive bleeding, persistent numbness, an allergic reaction to the antiseptic used 
to clean the thigh or infection. In general, all of these risks are well below 1% (1). Regarding bleeding 
risk, any volunteer with known coagulopathies will be excluded from participation. The majority of our 
TKA recipients take NSAIDS for joint pain pre-surgery and aspirin for deep vein thrombosis (DVT) 
prophylaxis post-surgery, although some with greater risk for DVT are placed on low MW heparin. For 
pre-surgical testing, the NSAIDS therapy will be stopped 5 d prior to the muscle biopsy, with prior 
approval of the prescribing physician, to limit bleeding during the biopsy. For the 2 wk post-surgery 
testing, none of the physicians will allow stoppage of aspirin or low MW heparin therapy. For those 
patients on low MW heparin, who are at greater risk for DVT, they will not be allowed to undergo 2 wk 
post-surgery testing. For patients on NSAIDs for pain at 2 wks post-surgery, For those patients on 
aspirin, this will not be stopped for the 2 wk post-surgery visit. Instead, pressure will be held longer 
following the biopsy to minimize bleeding. Historically, our laboratory’s practice for patients on aspirin 
was to not take them off of aspirin prior to the biopsy, a practice that was inherited from working with Dr. 
Ades as the study physician for cardiac disease patients. This practice had been long-standing in his 
studies that utilized muscle biopsies in cardiac disease populations and was only changed in Dr. Toth’s 
studies when one volunteer who was on aspirin developed a hematoma following her biopsy. However, 
the anti-thrombotic effects of aspirin will not dissipate with discontinuation of 5 d. For this reason, and 
because of the necessity of having TKA recipients on aspirin for DVT prophylaxis at the 2 wk post-
surgery time point, we will not stop this medication. At 5 wk post-surgery, most patients will be off of 
anti-thrombotic therapy (aspirin or low MW heparin), but, if not, the same rules as for the 2 wk visit will 
apply. Finally, for any patient taking NSAIDs for pain at the 2 wk or 5 wk visit, they will only be included 
with prior approval from the prescribing physician to stop the NSAIDs 5 d pre-biopsy, as well as the 
patient in accordance with their pain control. Our laboratory has never had an adverse event related to 
the muscle biopsy procedure and it will be performed by trained, qualified clinicians in a closely-
controlled, medical environment. There is risk for muscle soreness or injury resulting from whole body 
and whole muscle functional testing. Appropriate warm up exercises will be performed to prevent 
muscle soreness/injury. Finally, each DEXA scan exposes the volunteers to x-rays, although the total 
exposure is equivalent to approximately 1 d of normal daily background radiation and each CT scan of 
the mid-thigh exposes volunteers to the equivalent of 110 d of normal background radiation. Importantly, 
the exposure from the CT is focused on a single slice at mid-thigh. Any woman volunteer who is 
premenopausal will undergo a urine pregnancy test prior to either procedure to assure that she is not 
pregnant. 
NMES intervention: NMES is a generally safe procedure, delivered in the proposed study by an FDA 
approved device. Although evidence is limited, some have suggested that NMES could increase the risk 
of DVT, which may have serious health consequences. However, several published reports show that 
NMES significantly reduces the risk of developing DVTs (2) and we will actively exclude any individual 
with a known coagulopathy. Because of the location of the stimulating electrodes (upper leg), the risk of 
NMES dislodging a DVT is likely minimal. We will also exclude any prospective volunteers that currently 
have an implanted cardiac defibrillator or pacemaker, as this is contraindicated for NMES use (2). 
Patients may experience some painful muscle contractions as they first adjust the stimulus to a tolerable 
level, this will be quickly mitigated by reducing the stimulation intensity. After treatment, muscles 
soreness may occur. The level of fatigue and/or soreness, however, will be similar to that which occurs 
following a standard exercise training session and should dissipate over time as the volunteer’s muscles 
become accustomed to the electrically-stimulated contractions (ie, they become trained). In studies of 
the use of NMES in the post TKA population, our laboratories (including our co-I, Dr. Stevens-Lapsley, 
who has conducted NMES in NIH-funded RCTs; (3)) have never experienced an adverse event related 
to the use of NMES. 
Leg movement with Biostamp sensors: Wearing the sensors causes little to no discomfort in most 
individuals, similar to wearing a Band-Aid. The BioStamp nPoint sensors are not intended for use on 
patients with known allergies or hypersensitivities to adhesives or hydro-gel. In absence of a known 

 
 
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allergy or hypersensitivity, it is possible the sensor and/or adhesive may still cause mild discomfort, skin 
irritation, redness, rash or contact dermatitis in some individuals. The BioStamp nPoint sensors are not 
intended for use on patients who have implanted pacemakers, defibrillators, or other active implantable 
devices. As volunteers with these implanted devices are already excluded from study, this risk is 
obviated. There is a small risk that a participant’s electronic information could be accessed thereby 
affecting their confidentiality. 
 
Benefits: The direct benefit of the research to volunteers is minimal. NMES may improve skeletal 
muscle structure or function and, in turn, improve physical functional capacity, as our collaborator’s RCT 
demonstrated (3). Because of this, patients may experience improved physiological capacity, which 
could reduce disability post-surgery. If NMES is shown to have beneficial effects on skeletal muscle, 
further research and application of the technique to TKA recipients may assist in the development of 
more effective post-TKA care to mitigate long-term functional morbidity in these patients in the future, as 
well as provide compelling evidence to extend this intervention into other post-surgical populations to 
improve functional recovery. 
References cited above: 
1. 
Tarnopolsky, M. A., Pearce, E., Smith, K., and Lach, B. (2011) Suction-modified Bergström muscle biopsy technique: 
Experience with 13,500 procedures. Muscle Nerve 43, 716-725 
2. 
Houghton, P. E., Nussbaum, E. L., and Hoens, A. M. (2010) Electrophysical agents. Contraindications and 
precautions: an evidence-based approach to clinical decision making in physical therapy. Physiother Can 62, 1-80 
3. 
Stevens-Lapsley, J. E., Balter, J. E., Wolfe, P., Eckhoff, D. G., and Kohrt, W. M. (2012) Early neuromuscular electrical 
stimulation to improve quadriceps muscle strength after total knee arthroplasty: a randomized controlled trial. Phys 
Ther 92, 210-226 
 
Data Safety and Monitoring:   
Our study is a clinical trial based on the recently-revised NIH definition (NOT-OD-15-015), but not a 
phase III clinical trial. Thus, pursuant to NIH regulations, we had originally established a formal Data 
Safety Monitoring Plan, which would provide additional oversights to further protect against risk to safety 
and confidentiality. The Clinical Trial Branch of the NIA has reviewed our protocol and made the 
determination that our study could be monitored by an outside Safety Officer through a standard DSMP 
format. 
DSMP: The PI (Toth) and Dr. Nelms will monitor the safety of the research procedures for this study. 
Dr. Toth will be available on-site for all major experimental procedures (eg, muscle biopsy) that might 
reasonably be expected to pose safety concerns for volunteers. In this context, the PI will be readily 
available to monitor volunteer safety throughout the study. If an event occurs that affects participant 
safety, the PI and/or Dr. Nelms will alert the Safety Officer (Dr. Richard Wilson, M.D.; Director of 
Inpatient Rehabilitation and Stroke Rehabilitation; MetroHealth Medical Center; Cleveland OH), who will 
adjudicate the event with respect to its severity, expectedness and relatedness to participation in the 
study according to the aforementioned criteria. A formal copy of the DSMP that has been approved by 
the Clinical Trial Branch of the NIA is now included with this Protocol. 
 
Adverse Event and Unanticipated Problem (UAP) Reporting: .   
The PI (Toth), the study coordinator and Dr. Nelms will monitor the safety of the research 
procedures/interventions for this study. Dr. Toth will be available on-site for all major experimental 
procedures (eg, muscle biopsy) that might reasonably be expected to pose safety concerns for 
volunteers. In this context, study personnel will be readily available to monitor volunteer safety 
throughout the study. If an event occurs that affects participant safety, the PI will alert Dr. Nelms and the 
Safety Officer, who will adjudicate the event with respect to its severity, expectedness and relatedness 
to participation in the study. Because numerous studies in our laboratories and others have 
demonstrated the safety of this regimen of testing in patients with a broad range of clinical backgrounds 
(e.g., heart failure patients, cancer patients, advanced-stage, knee OA patients; healthy elderly; see PI’s 
Biosketch), as well as the safety of NMES, we expect minimal problems related to testing or the NMES 
intervention. The research coordinator and Dr. Nelms will remain unblinded during the studies, as they 
will not specifically participate in testing, and to enable them to respond directly to any adverse 
event/unanticipated problem that may arise in either treatment group. Considering the low risk nature of 

 
 
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these studies, we have not incorporated "stoppage criteria" for the overall study. Instead, the Safety 
Officer will decide whether an individual participant should continue with the study following occurrence 
of any adverse events or unanticipated problems, taking into consideration what is in the best interest of 
each individual patient. 
Adverse events will be reported by one of 3 mechanisms. First, the joint University of 
Vermont/University of Vermont Medical Center (UVMC) Committee for Human Subject Research 
Adverse Event Reporting Document. These reports will be forwarded to the office of the Committee for 
Human Research in the Medical Science (CHRMS) within 5 days of the event. Reporting any adverse 
events will be the responsibility of the PI. The CHRMS will make a determination as to whether 
additional reporting requirements are indicated. Second, the UVMC Patient Safety Reporting system 
(SAFE), which may be initiated by health care center staff or study personnel. These forms will be 
forwarded within 3 days to the PI, UVMC Risk Management Office, CHRMS and other appropriate 
agencies, as indicated by the nature of the report. Finally, the UVMC Medication/IV Event Report Form, 
with distribution and timing as noted above. This latter mechanism might be used with events related to 
blood sampling. Reviews of protocol specific adverse events will be performed no less than annually. 
Additionally, any adverse event that occurs will be forwarded to the PI for reporting to the Human 
Subject Research Protection Office within 1 week of occurrence. Of note, these protections against risk 
include both physical risks to the volunteers, as well as risks associated with any breach in 
confidentiality. 
On an annual basis, Drs. Toth, Nelms and the Safety Officer will assess data being gathered and 
safety of volunteers to assess the pattern or frequency of events to identify occurrence of any event or 
problem that significantly alters the safety profile of the procedures being performed, unless occurrence 
of a serious adverse event or unanticipated problem necessitates re-evaluation of the expected risk of 
the study procedures at an earlier time point. Additionally, they will evaluate data collection and storage 
to ensure the confidentiality of data and quality. Each of these evaluations will be followed by reports of 
study progress and patient safety to the University of Vermont CHRMS via yearly progress reports and 
to the appropriate NIH program officer. The report will include information regarding study status and 
safety of volunteers (occurrence of AEs/SAEs. This report will also be forwarded to the NIH Program 
Officer for his review. 
Withdrawal Procedures:  Define the precise criteria for withdrawing subjects from the study.   Include a description of study 
requirements for when a subject withdraws him or herself from the study (if applicable). 
Volunteers will be withdrawn if the research team, clinician and/or safety officer feels that further 
participation in the study or performance of any procedure associated with this study would, in any way, 
put the volunteer at undue risk or not be in their best interest. Moreover, volunteers may be withdrawn if 
s/he fails to attend scheduled visits or do not comply with instructions from research staff. 
Sources of Materials:  Identify sources of research material obtained from individually identifiable human subjects in the form 
of specimens, records or data.  Indicate whether the material or data will be obtained specifically for research purposes or 
whether use will be made of existing specimens, records or data. 
An individual research record will be kept on each volunteer in compliance with HIPAA standards. This 
record will contain identifying data, demographic information and results from all clinical research 
measurements and evaluations. The results of all testing will be kept confidential. In addition, skeletal 
muscle tissue samples will be taken and will be used for measurement of muscle size, structure and 
function. All materials gathered in conjunction with the proposed studies will be used for research 
purposes only and will be available only to research personnel working on these studies, who have 
obtained proper training in human subjects research and privacy protection.  
 
DRUG AND DEVICE INFORMATION  
 
Drug (s) 
X 
Not applicable 
Device (s) 
 
Not applicable 
Device name and indications  
The interventional device used in this study: EMPI Continuum complete electrotherapy system has 
received FDA approval (501K: K093324) for retarding disuse-related atrophy, which we believe is one of 
the primary mechanisms whereby muscle adaptations evolve in TKA recipients in the early, post-
surgical period. That is, muscle disuse secondary to pain, limited range of motion and muscle weakness 

 
 
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(the latter being due to neural inhibition caused by joint pain/swelling) causes skeletal muscle fiber 
atrophy and weakness and mitochondrial rarefaction and dysfunction. 
Is it FDA approved: 
Yes. It is approved to mitigate muscle atrophy/dysfunction associated with muscle disuse (501K: 
K093324) (see Appendix 3). 
Risk assessment (non-significant/significant risk)  
The device (and similar devices) has been used extensively in the orthopedic and neural rehabilitation 
settings by physical and occupational therapists and in numerous disease states (heart failure, chronic 
obstructive pulmonary disease, knee replacement) to improve muscle size and function in clinical trial 
settings. Thus, NMES is generally a safe modality, with a long safety record. Although evidence is 
limited, some have suggested that NMES could increase the risk of dislodging a deep vein thrombosis 
(DVT) because of the rhythmic muscle contractions induced by the electrical stimulation. However, 
several published reports show that NMES significantly reduces the risk of developing DVTs. In fact, the 
device we are using is FDA-approved for prevention of DVT of the calf muscles immediately following 
surgery, as it would function similar to intermittent pneumatic compression. Moreover, we will actively 
exclude any individual with a known coagulopathy or DVT. Because of the location of the stimulating 
electrodes (upper leg), the risk of NMES dislodging a DVT is likely minimal. There are also several case 
reports that NMES may be sensed by cardiac defibrillators as an arrhythmia, causing the device to 
discharge inappropriately. However, interference with ICDs mostly involved low frequency stimulation of 
the upper or lower back. In contrast, a more recent study has shown that higher frequency stimulation of 
the leg muscles does not cause electromagnetic interference with the device (1). Regarless, consistent 
with current clinical practice guidelines (2), we will exclude any volunteers that currently have an 
implanted cardiac defibrillator or pacemaker. Finally, during the first couple of NMES sessions, muscle 
soreness may occur, but this is comparable to what might occur with classical exercise training and 
dissipates over time.  
Literature cited 
1. 
Kamiya, K., Satoh, A., Niwano, S., Tanaka, S., Miida, K., Hamazaki, N., Maekawa, E., Matsuzawa, R., Nozaki, K., 
Masuda, T., and Ako, J. Safety of neuromuscular electrical stimulation in patients implanted with cardioverter 
defibrillators. Journal of Electrocardiology 49, 99-101 
2. 
Houghton, P. E., Nussbaum, E. L., and Hoens, A. M. (2010) Electrophysical agents. Contraindications and 
precautions: an evidence-based approach to clinical decision making in physical therapy. Physiother Can 62, 1-80 
 
 
Inclusion of Minorities and Women:  .  
Inclusion of Women 
     This study will include equal numbers of men and women. 
Inclusion of Minorities 
     Every effort will be made to recruit minorities for the proposed studies. The contribution of minorities 
to the total population of Vermont is 3.2%, with a similar minority profile in Chittenden County (3.6%), 
where the University of Vermont (UVM) is located.  
Inclusion of Children:. 
The proposed studies will not include children. The rationale for this decision is based on the fact that 
total knee replacement is confined to the adult/ older adult population.