title: Lack of Correlation between Dynamic Balance and Hamstring-to-Quadriceps Ratio in Patients with Chronic Anterior Cruciate Ligament Tears.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the quadriceps and hamstring muscle strength and hamstring-to-quadriceps (HQ) ratio, as well as the relationships of these parameters with dynamic balance, in patients with anterior cruciate ligament (ACL) rupture.
  
  
  METHODS
  We compared 25 patients diagnosed with chronic unilateral ACL tears and 25 age-matched healthy volunteers. The maximal torque of the quadriceps and hamstring and dynamic balance were measured.
  
  
  RESULTS
  Although the isokinetic maximal peak torques were about 50% lower in the quadriceps (57%, p<0.001) and hamstring (56%, p=0.001) muscles in the chronic ACL tear group than in the control group, their HQ ratios were similar (56%±17% vs. 58%±6%, p=0.591). HQ ratio was significantly correlated with anterior-posterior stability index (r=-0.511, p=0.021) and overall stability index (r=-0.476, p=0.034) in control group, but these correlations were not observed in chronic ACL tear group.
  
  
  CONCLUSIONS
  Thigh muscle strength was about 50% lower in the chronic ACL tear group than in the control group, but the HQ ratio was similar. The dynamic balance of the knee was not influenced by thigh muscle strength but was influenced by HQ ratio in healthy young individuals. However, HQ ratio was not correlated with dynamic knee balance in chronic ACL tear patients.
authors.affiliation: Department of Orthopaedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. ; Department of Sports Medical Center, Korea University College of Medicine, Seoul, Korea.
authors.forename: Dae-Hee
authors.initials: DH
authors.lastname: Lee
authors.affiliation: Department of Sports Medical Center, Korea University College of Medicine, Seoul, Korea.
authors.forename: Jin-Hyuck
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Sports Medical Center, Korea University College of Medicine, Seoul, Korea.
authors.forename: Hye-Jin
authors.initials: HJ
authors.lastname: Jeong
authors.affiliation: Department of Sports Medical Center, Korea University College of Medicine, Seoul, Korea.
authors.forename: Seok-Joo
authors.initials: SJ
authors.lastname: Lee
keywords: Anterior cruciate ligament; Chronic tear; Muscle strength; Postural balance