title: Do Muscle Strength Deficits of the Uninvolved Hip and Knee Exist in Young Athletes Before Anterior Cruciate Ligament Reconstruction?
abstract: BACKGROUND
  Muscle strength of the involved limb is known to be decreased after injury. Comparison with the uninvolved limb has become standard of practice to measure progress and for calculation of limb symmetry indices (LSIs) to determine readiness to return to sport. However, some literature suggests strength changes in the uninvolved limb also are present after lower extremity injury.
  
  
  OBJECTIVE
  To examine the uninvolved limb strength in a population of adolescent athletes after an anterior cruciate ligament (ACL) injury and compare strength values with those of the dominant limb in a healthy control group.
  
  
  METHODS
  Cohort study; Level of evidence, 3.
  
  
  METHODS
  A total of 64 athletes were enrolled in this study, including 31with injured ACLs (mean age, 15.6 ± 1.4 years) and 33 healthy controls (mean age, 14.9 ± 1.9 years). The median time from injury to testing was 23 days for the ACL-injured group. Participants underwent Biodex isokinetic strength testing at 60 deg/s to assess quadriceps and hamstring strength. Isometric hip strength (abduction, extension, external rotation) was measured using a handheld dynamometer. The muscle strength of the uninvolved limb of the ACL-injured group was compared with that of the dominant limb of the healthy control group.
  
  
  RESULTS
  The results showed a significant difference in quadriceps muscle strength between the 2 study groups (P< .001). Isokinetic quadriceps strength of the uninvolved limb in the ACL group was significantly decreased by 25.5% (P< .001) when compared with the dominant limb of the control group.
  
  
  CONCLUSIONS
  The results of this study demonstrate a decreased isokinetic strength of the quadriceps muscle in the uninvolved limb after ACL injury as compared with healthy controls. Consideration should be taken when using the uninvolved limb for comparison when assessing quadriceps strength in a population with an ACL injury.
authors.affiliation: Texas Health Ben Hogan Sports Medicine, Fort Worth, Texas, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Hannon
authors.affiliation: Texas Woman's University, Dallas, Texas, USA.
authors.forename: Sharon
authors.initials: S
authors.lastname: Wang-Price
authors.affiliation: Texas Health Ben Hogan Sports Medicine, Fort Worth, Texas, USA.
authors.forename: Shiho
authors.initials: S
authors.lastname: Goto
authors.affiliation: Texas Health Ben Hogan Sports Medicine, Fort Worth, Texas, USA.
authors.forename: J Craig
authors.initials: JC
authors.lastname: Garrison
authors.affiliation: Texas Health Ben Hogan Sports Medicine, Fort Worth, Texas, USA.
authors.forename: James M
authors.initials: JM
authors.lastname: Bothwell
keywords: ACL; anterior cruciate ligament; return to sport