title: Evaluation of electromyographic biofeedback for the quadriceps femoris: a systematic review.
abstract: OBJECTIVE
  To critically review evidence for the effectiveness of electromyographic biofeedback (EMGB) of the quadriceps femoris muscle in treating various knee conditions.
  
  
  METHODS
  Databases used to locate randomized controlled trials included PubMed (1980-2010), Cumulative Index of Nursing and Allied Health Literature (CINAHL, 1995-2007), Web of Science (1986-2010), SPORTDiscus (1990-2007), and Physiotherapy Evidence Database (PEDro). Key words were knee and biofeedback.
  
  
  METHODS
  The criteria for selection were clinical randomized controlled trials in which EMGB of the quadriceps femoris was used for various knee conditions of musculoskeletal origin. Trials were excluded because of research designs other than randomized controlled trials, articles published in a non-English language, inclusion of healthy research participants, inability to identify EMGB as the source of clinical improvement, and lack of pain, functional outcome, or quadriceps torque as outcome measures.
  
  
  METHODS
  Twenty specific data points were abstracted from each clinical trial under the broad categories of attributes of the patient and injury, treatment variables for the EMGB group, treatment variables for the control group, and attributes of the research design.
  
  
  RESULTS
  Eight trials yielded a total of 319 participants with patellofemoral pain syndrome (n = 86), anterior cruciate ligament reconstruction (n = 52), arthroscopic surgery (n = 91), or osteoarthritis (n = 90). The average methodologic score of the included studies was 4.6/10 based on PEDro criteria. Pooled analyses demonstrated heterogeneity of the included studies, rendering the interpretation of the pooled data inappropriate. The EMGB appeared to benefit short-term postsurgical pain or quadriceps strength in 3 of 4 postsurgical investigations but was ineffective for chronic knee conditions such as patellofemoral pain and osteoarthritis in all 4 studies. Because the findings are based on limited data, caution is warranted until more randomized controlled trials are conducted to support or refute the general trends observed in this report.
authors.affiliation: Department of Exercise Science, Bloomsburg University of Pennsylvania, 400 East Second Street, Bloomsburg, PA 17815-1301, USA. nwasiele@bloomu.edu
authors.forename: Noah J
authors.initials: NJ
authors.lastname: Wasielewski
authors.forename: Tonya M
authors.initials: TM
authors.lastname: Parker
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Kotsko
mesh_terms: D059549:Anterior Cruciate Ligament Reconstruction; D001182:Arthroscopy; D006801:Humans; D007718:Knee Injuries / Q000534:rehabilitation / Q000628:therapy*; D058765:Neurofeedback; D010003:Osteoarthritis / Q000534:rehabilitation / Q000628:therapy; D017063:Outcome Assessment, Health Care; D046788:Patellofemoral Pain Syndrome / Q000534:rehabilitation / Q000628:therapy*; D052097:Quadriceps Muscle / Q000293:injuries*; D016032:Randomized Controlled Trials as Topic