title: Knee recurvatum in gait: a study of associated knee biomechanics.
abstract: OBJECTIVE
  To quantitatively evaluate peak knee extensor torque values imparted to the posterior knee structures during gait in patients with knee recurvatum compared with torque values observed in control subjects, and to assess the predictive value of the degree of knee hyperextension and other clinical factors in estimating peak knee extensor torque.
  
  
  METHODS
  A retrospective analysis of clinical and quantitative gait data obtained from patients and control subjects.
  
  
  METHODS
  A gait laboratory.
  
  
  METHODS
  Forty-one consecutive patients with neurologically based impairments presenting with knee hyperextension during gait (52 limbs) and 46 able-bodied control subjects.
  
  
  METHODS
  Peak knee extensor torque during the stance period of the gait cycle.
  
  
  RESULTS
  Although overall, the patient average peak extensor torque was significantly greater (p < .001) than the control subjects' average value, knee extensor torques were within or below a +/- 1 standard deviation range for control subjects in 25% (13) of limbs tested. Peak knee hyperextension angle was a poor predictor of peak extensor torque; there was statistical significance (coefficient .061,p < .001) only for hyperextension angles of < or = 4 degrees. Multiple regression incorporating hyperextension angle and other clinical variables to predict peak knee extensor torque resulted in an adjusted r2 of .53.
  
  
  CONCLUSIONS
  Patients with knee recurvatum have variable peak extensor torque values associated with their knee hyperextension. Knowledge of knee hyperextension angle and other clinical factors are only partially useful in predicting a patient's peak knee extensor torque imparted to the posterior knee structures during walking.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA 02114, USA.
authors.forename: D C
authors.initials: DC
authors.lastname: Kerrigan
authors.forename: L C
authors.initials: LC
authors.lastname: Deming
authors.forename: M K
authors.initials: MK
authors.lastname: Holden
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D001927:Brain Diseases / Q000503:physiopathology*; D001930:Brain Injuries / Q000503:physiopathology*; D005260:Female; D005684:Gait; D006801:Humans; D007717:Knee / Q000503:physiopathology*; D008297:Male; D011237:Predictive Value of Tests; D016059:Range of Motion, Articular; D012044:Regression Analysis; D012189:Retrospective Studies; D014102:Torsion Abnormality