Muscle & mechanical loading
Neuromuscular Electrical Stimulation (NMES) after Knee Replacement
Graded on: early quadriceps strength and mobility after total knee replacement, compared with usual care (dynamometer strength, timed up-and-go).
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How this letter has changedLatest: October 2026 · Corrected.
The replication block listed the Cleveland trial (Klika et al., 2022; PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 32610358) as unclear funding when the report states funding by Cymedica Orthopaedics, the device maker, now stated; and it omitted the cleaner independent replication on dynamometer strength, Yoshida et al. (2017; PMID 28610968), now listed. The as-studied dose and duration fit the Colorado trial only and now state the three trials' differing regimens. Avramidis 2011 (PMID 21410130) is relabeled as vastus medialis stimulation with mobility and self-report outcomes, and DeJong 2020 (PMID 32360105) as patterned stimulation, a different form. Added: Levine 2013 (PMID 23464951), home stimulation noninferior to supervised therapy; Cheuy 2023 (PMID 35856287), same Colorado group; Monaghan 2010 Cochrane (PMID 20091621) as context. The letter stays A: instrument-measured strength replicated by independent groups is what the written A asks for; the basis now states the case for B so the editor can weigh it. Applied the written grade definition under the editor's standing instruction of October 2026 (Arnold Sandlow, D.C.).PMID 20091621 PMID 21410130 PMID 23464951 PMID 28610968 PMID 32360105 PMID 32610358 PMID 35856287
New device record, graded for one narrow claim: early quadriceps strength and mobility after total knee replacement, compared with usual care. Strength measured on a dynamometer and timed mobility tests improved in randomized trials from independent groups in the United States, Japan and Greece (Stevens-Lapsley et al., Phys Ther 2012; PMID 22095207. Klika et al., J Knee Surg 2022; PMID 32610358), and a meta-analysis A study that pools the numbers from several trials into one combined estimate. of nine trials still found a strength benefit at 12 months (Peng et al., Front Med 2021; PMID 34926522). The letter does not say stimulation beats a progressive strengthening program: in the largest trial, 200 patients, it added nothing when combined with one (Petterson et al., Arthritis Rheum 2009; PMID 19177542).PMID 22095207 PMID 32610358 PMID 34926522 PMID 19177542
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Neuromuscular electrical stimulation uses pads on the skin to make the thigh muscles tighten. After knee replacement surgery, teams in three countries found faster gains in thigh strength and walking tests than usual care. A pooled review of nine trials still saw a strength gain at one year. But in the largest trial, 200 patients, it added nothing to a good strength program. Most positive trials did not hide the treatment from the testers. It is not used over a pacemaker, a blood clot, or broken or infected skin.
A letter describes the human evidence, not the product, the manufacturer, or the intervention's worth.
See the full evidence record →Graded on Early quadriceps strength and mobility after total knee replacement, compared with usual care (dynamometer strength, timed up-and-go).
Why this gradeThe reasoning, and what the grade does not cover.
Grade A for one specific claim: early quadriceps strength and mobility after total knee replacement, compared with usual care. The outcomes are the ones the Grade A rule names, strength measured on a dynamometer and timed mobility tests, and the effect was found by independent groups in three countries, with a meta-analysis of nine trials still showing a strength benefit at 12 months.
WHAT THIS GRADE DOES NOT COVERit does not say stimulation beats a well-run progressive strengthening program. In the largest trial, 200 patients, stimulation added to progressive strengthening gave no additional benefit, and a 363-patient trial of patterned stimulation, a different form, found no gain in gait speed. Most positive trials compared stimulation with usual care, did not match total treatment time, and did not blind the tester. The benefit is largest in the first weeks, and several pooled results sit below the difference usually called clinically important. It does not cover knee osteoarthritis without surgery, other operations, or healthy older adults.
THE REPLICATION IS NARROWthe three replicating trials each enrolled about 66 patients, used different doses and durations, and one was funded by the device maker. The letter is A because the written rule asks for an instrument-measured functional outcome replicated by independent groups, which these trials are; a reader who weighs the unblinded testing, the unmatched treatment time and the null matched-volume trial could hold it at B.
Shared endpoint The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score.: Quadriceps strength on a dynamometer and timed mobility after total knee replacement, NMES added to usual care versus usual care
- University of Colorado, USA (Stevens-Lapsley): Greater quadriceps strength at 3.5 weeks, still significant at 52 weeks; testers not blinded. PMID 22095207 · Funding: academic; NIH-funded
- Japan, hospital arthroplasty center (Yoshida): Motor-level stimulation beat control on maximum voluntary isometric quadriceps contraction and the 2-minute walk; single-blind, 66 patients, 45-minute sessions 5 days a week for 2 weeks. PMID 28610968 · Funding: not stated in the indexed record
- Cleveland Clinic, USA (Klika): Quadriceps strength gains against losses in controls at 3 and 6 weeks; faster timed up and go at 6 and 12 weeks; home use of at least 200 minutes a week for 12 weeks. PMID 32610358 · Funding: Cymedica Orthopaedics, the maker of the device studied
What the replication does not cover: Testers were not blinded in the Colorado trial. NMES was added to usual care, not compared with a matched strengthening program; the one trial that matched treatment volume (Petterson 2009, PMID 19177542, 200 patients) found no added benefit. The device maker funded the Cleveland trial. Dose and duration differed across the replicating trials.
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Not for use over an implanted pacemaker or defibrillator, over a known or suspected deep vein thrombosis, or over broken or infected skin. Skin irritation under the electrodes was the most common complaint in the trials. Settings and electrode placement after surgery are set by the treating clinician.
The evidence, in fullEleven papers, each linked to its PubMed record.
Stevens-Lapsley et al. (Phys Ther, 2012; PMID 22095207): 66 patients randomized to usual rehabilitation with or without quadriceps stimulation starting 48 hours after surgery; quadriceps strength, timed up-and-go, stair climbing and 6-minute walk were better at 3.5 weeks and strength remained better at 52 weeks. Testers were not blinded. Klika et al. (J Knee Surg, 2022; PMID 32610358): 66 patients randomized 2 to 1 to home stimulation or usual care; strength better at 3 and 6 weeks and timed up-and-go better at 6 and 12 weeks; funded by the device maker, Cymedica Orthopaedics. Yoshida et al. (Arch Phys Med Rehabil, 2017; PMID 28610968): 66 patients, single-blind, three arms; motor-level stimulation beat control on isometric strength and 2-minute walk. Avramidis et al. (Orthopedics, 2011; PMID 21410130): 70 patients, stimulation of the vastus medialis only; faster walking speed and better Oxford Knee and Knee Society scores at 6 and 12 weeks, with no dynamometer strength outcome. Levine et al. (Orthopedics, 2013; PMID 23464951): 70 patients; home stimulation plus home range-of-motion exercise was noninferior to supervised physical therapy at 6 weeks, a different comparison. Cheuy et al. (J Orthop Res, 2023; PMID 35856287): 19 patients, NIH-funded, same Colorado group; stimulation preserved strength and type II fiber size at 2 weeks, not independent replication. Monaghan et al. (Cochrane, 2010; PMID 20091621): the earlier review judged two high-bias studies inconclusive, the point from which the evidence base grew. Peng et al. (Front Med, 2021; PMID 34926522): meta-analysis of 9 randomized trials, 691 patients; strength standardized mean difference 0.81 within one month and 0.46 at 12 months. Bistolfi et al. (Am J Phys Med Rehabil, 2018; PMID 29016401): meta-analysis of 6 trials; benefit early, not at medium or long term. Null trials kept in the record: Petterson et al. (Arthritis Rheum, 2009; PMID 19177542), 200 patients, stimulation added to progressive strengthening gave no additional benefit at 3 or 12 months; DeJong et al. (J Arthroplasty, 2020; PMID 32360105), 363 patients, tested patterned electrical neuromuscular stimulation added to a bike or an unweighting treadmill, a different stimulation form, and found no gain in gait speed; it does not test this record's motor-level protocol directly.
Quadriceps strength on a handheld or isokinetic dynamometer and timed up-and-go before surgery, then at 3, 6 and 12 weeks. The trials found their clearest effect in the first 6 weeks.
Evidence notes: randomized trial, meta-analysis
Endpoint graded: Early quadriceps strength and mobility after total knee replacement, compared with usual care (dynamometer strength, timed up-and-go) (functional)
Last reviewed: September 2026
Educational use only · Not medical advice · EBL grades published human evidence and does not recommend treatment. Stopping a prescription is a decision for your physician.
As studiedDose, form, population and duration for every use.
Consumer muscle stimulators are sold for general toning and strength; this grade describes clinician-set quadriceps stimulation after knee replacement only.
A grade describes the intervention that was tested. Where the product on the shelf differs from it, this says so.
Primary evidenceEleven papers, each linked to its PubMed record.
Stevens-Lapsley et al. (Phys Ther, 2012; PMID 22095207): 66 patients randomized to usual rehabilitation with or without quadriceps stimulation starting 48 hours after surgery; quadriceps strength, timed up-and-go, stair climbing and 6-minute walk were better at 3.5 weeks and strength remained better at 52 weeks. Testers were not blinded. Klika et al. (J Knee Surg, 2022; PMID 32610358): 66 patients randomized 2 to 1 to home stimulation or usual care; strength better at 3 and 6 weeks and timed up-and-go better at 6 and 12 weeks; funded by the device maker, Cymedica Orthopaedics. Yoshida et al. (Arch Phys Med Rehabil, 2017; PMID 28610968): 66 patients, single-blind, three arms; motor-level stimulation beat control on isometric strength and 2-minute walk. Avramidis et al. (Orthopedics, 2011; PMID 21410130): 70 patients, stimulation of the vastus medialis only; faster walking speed and better Oxford Knee and Knee Society scores at 6 and 12 weeks, with no dynamometer strength outcome. Levine et al. (Orthopedics, 2013; PMID 23464951): 70 patients; home stimulation plus home range-of-motion exercise was noninferior to supervised physical therapy at 6 weeks, a different comparison. Cheuy et al. (J Orthop Res, 2023; PMID 35856287): 19 patients, NIH-funded, same Colorado group; stimulation preserved strength and type II fiber size at 2 weeks, not independent replication. Monaghan et al. (Cochrane, 2010; PMID 20091621): the earlier review judged two high-bias studies inconclusive, the point from which the evidence base grew. Peng et al. (Front Med, 2021; PMID 34926522): meta-analysis of 9 randomized trials, 691 patients; strength standardized mean difference 0.81 within one month and 0.46 at 12 months. Bistolfi et al. (Am J Phys Med Rehabil, 2018; PMID 29016401): meta-analysis of 6 trials; benefit early, not at medium or long term. Null trials kept in the record: Petterson et al. (Arthritis Rheum, 2009; PMID 19177542), 200 patients, stimulation added to progressive strengthening gave no additional benefit at 3 or 12 months; DeJong et al. (J Arthroplasty, 2020; PMID 32360105), 363 patients, tested patterned electrical neuromuscular stimulation added to a bike or an unweighting treadmill, a different stimulation form, and found no gain in gait speed; it does not test this record's motor-level protocol directly.
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