title: Neuromuscular and biomechanical adaptations of patients with isolated deficiency of the posterior cruciate ligament.
abstract: BACKGROUND
  Functional adaptations of patients with posterior cruciate ligament deficiency (grade II) are largely unknown despite increased recognition of this injury.
  
  
  OBJECTIVE
  Posterior cruciate ligament-deficient subjects (grade II, 6- to 10-mm bilateral difference in posterior translation) will present with neuromuscular and biomechanical adaptations to overcome significant mechanical instability during gait and drop-landing tasks.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Bilateral comparisons were made among 10 posterior cruciate ligament-deficient subjects using radiographic, instrumented laxity, and range of motion examinations. Biomechanical and neuromuscular characteristics of the involved limb of the posterior cruciate ligament-deficient subjects were compared to their uninvolved limb and to 10 matched control subjects performing gait and drop-landing tasks.
  
  
  RESULTS
  Radiographic (15.3 +/- 2.9 to 5.6 +/- 3.7 mm; P = .008) and instrumented laxity (6.3 +/- 2.0 to 1.4 +/- 0.5 mm; P < .001) examinations demonstrated significantly greater posterior displacement of the involved knee within the posterior cruciate ligament-deficient group. The posterior cruciate ligament-deficient group had a significantly decreased maximum knee valgus moment and greater vertical ground reaction force at midstance during gait compared to the control group. During vertical landings, the posterior cruciate ligament-deficient group demonstrated a significantly decreased vertical ground reaction force loading rate. All other analyses reported no significant differences within or between groups.
  
  
  CONCLUSIONS
  Posterior cruciate ligament-deficient subjects demonstrate minimal biomechanical and neuromuscular differences despite significant clinical laxity.
  
  
  CONCLUSIONS
  The findings of this study indicate that individuals with grade II posterior cruciate ligament injuries are able to perform gait and drop-landing activities similar to a control group without surgical intervention.
authors.affiliation: Neuromuscular Research Laboratory, UPMC Center for Sports Medicine, 3200 South Water Street, Pittsburgh, PA 15203, USA. tcs15@pitt.edu
authors.forename: Cristián A
authors.initials: CA
authors.lastname: Fontboté
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Sell
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Laudner
authors.forename: Marcus
authors.initials: M
authors.lastname: Haemmerle
authors.forename: Christina R
authors.initials: CR
authors.lastname: Allen
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Margheritini
authors.forename: Scott M
authors.initials: SM
authors.lastname: Lephart
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Harner
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D005684:Gait; D006801:Humans; D007718:Knee Injuries / Q000503:physiopathology*; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D016119:Posterior Cruciate Ligament / Q000293:injuries*