title: Biomechanical analysis of the knee with partial anterior cruciate ligament disruption: quantitative evaluation using an electromagnetic measurement system.
abstract: OBJECTIVE
  To investigate the biomechanical function of anterior cruciate ligament (ACL) remnants in ACL-deficient knees with both partial and complete tears.
  
  
  METHODS
  Twenty partial ACL-deficient (group P), 20 complete ACL-deficient (group C), and 40 contralateral ACL-intact knees were examined. The end point during the Lachman test, side-to-side differences of KT-1000 measurements, and the pivot shift test were evaluated. Additionally, the side-to-side difference of anterior tibial translation during the Lachman test and the acceleration during the pivot shift test were calculated using an electromagnetic measurement system (EMS).
  
  
  RESULTS
  The end point was found in 9 patients in group P, whereas it was not detected in group C. In KT-1000 measurements, the mean side-to-side differences were 3.8 ± 2.4 mm in group P and 5.4 ± 2.3 mm in group C. There was a significant difference between these 2 groups (P < .05). In the pivot shift test evaluation in group P, one patient was evaluated as grade 0, 17 patients as grade 1+, and 2 patients as grade 2+. In group C, 10 patients were evaluated as grade 1+, 9 patients as grade 2+, and one patient as grade 3+. Using the EMS, mean side-to-side differences during the Lachman test were 3.1 ± 2.1 mm in group P and 7.2 ± 3.2 mm in group C. The anterior-posterior displacement in group P was significantly less than that in group C (P < .05). In the quantitative pivot shift test, the mean acceleration in the contralateral ACL-intact knees was -632.7 ± 254.5 mm/s(2), whereas it was -1107.5 ± 398.9 mm/s(2) in group P and -1652.2 ± 754.9 mm/s(2) in group C. Significant differences were detected between the 3 knee conditions (P < .05).
  
  
  CONCLUSIONS
  The quantitative assessments of knees with partial ACL ruptures during the Lachman test and the pivot shift test using the EMS showed less laxity than did knees with complete ACL tears, whereas their laxity was greater than the contralateral knees with intact ACLs.
  
  
  METHODS
  Level III, diagnostic study of nonconsecutive patients.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Kobe University, Kobe, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Araki
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Kuroda
authors.forename: Takehiko
authors.initials: T
authors.lastname: Matsushita
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Seiji
authors.initials: S
authors.lastname: Kubo
authors.forename: Kouki
authors.initials: K
authors.lastname: Nagamune
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kurosaka
mesh_terms: D000293:Adolescent; D016118:Anterior Cruciate Ligament / Q000503:physiopathology; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction; D001182:Arthroscopy; D001696:Biomechanical Phenomena / Q000502:physiology; D055590:Electromagnetic Phenomena; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis / Q000503:physiopathology*; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012421:Rupture / Q000503:physiopathology; D013977:Tibia / Q000503:physiopathology; D055815:Young Adult