title: The sitting active and prone passive lag test: an inter-rater reliability study.
abstract: OBJECTIVE
  To determine inter-rater reliability in identifying a knee extension lag using the sitting active and prone passive lag test (SAPLT).
  
  
  METHODS
  56 patients with a diagnosis of knee pain were randomly assigned and independently examined by two physical therapists at a time, to determine the presence of an active or a passive extension lag at the knee. An active lag was determined by the inability of the erectly seated subject to actively extend the involved knee in maximal dorsiflexion of the ankle to the same level as the normal knee held in maximal extension and ankle in maximal dorsiflexion, as seen by the levels of the toes. A passive lag was determined by placing the subject prone with the knees just past the edge of the table and determining the high position of the heel in a fully resting extension position compared to the heel on the normal side.
  
  
  RESULTS
  For the sitting active lag test, the inter-rater reliability was 'good' (Kappa 0.792, SE of kappa 0.115, 95% confidence interval). For the prone passive lag test, the inter-rater reliability was 'good' (Kappa 0.636, SE of kappa 0.136, 95% confidence interval).
  
  
  CONCLUSIONS
  The SAPLT may be incorporated as a simple yet effective test to determine the presence of a knee extension lag. It identifies the type of restraint, active, passive or both, and is suggestive of the most appropriate management.
authors.affiliation: Institute of Therapeutic Sciences, Residency in Orthopaedic Physical Therapy, Fellowship in Orthopaedic Manual Physical Therapy, Alternative Rehab Inc., 20319 Farmington Road, Livonia, MI 48152, USA. Electronic address: institutemanualpt@yahoo.com.
authors.forename: Deepak
authors.initials: D
authors.lastname: Sebastian
authors.affiliation: Institute of Therapeutic Sciences, Residency in Orthopaedic Physical Therapy, Fellowship in Orthopaedic Manual Physical Therapy, Alternative Rehab Inc., 20319 Farmington Road, Livonia, MI 48152, USA.
authors.forename: Raghu
authors.initials: R
authors.lastname: Chovvath
authors.affiliation: Institute of Therapeutic Sciences, Residency in Orthopaedic Physical Therapy, Fellowship in Orthopaedic Manual Physical Therapy, Alternative Rehab Inc., 20319 Farmington Road, Livonia, MI 48152, USA.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Malladi
mesh_terms: D018771:Arthralgia / Q000453:epidemiology* / Q000534:rehabilitation*; D004185:Disability Evaluation; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D015588:Observer Variation; D026741:Physical Therapy Modalities; D016059:Range of Motion, Articular; D015203:Reproducibility of Results
keywords: Active lag; Knee extension lag; Passive lag; Reliability; Special test