title: Should the Ipsilateral Hamstrings Be Used for Anterior Cruciate Ligament Reconstruction in the Case of Medial Collateral Ligament Insufficiency? Biomechanical Investigation Regarding Dynamic Stabilization of the Medial Compartment by the Hamstring Muscles.
abstract: BACKGROUND
  Semitendinosus and gracilis muscles are frequently harvested for autologous tendon grafts for cruciate ligament reconstruction. This study investigated the joint-stabilizing effects of these hamstring muscles in cases of insufficiency of the medial collateral ligament (MCL).
  
  
  OBJECTIVE
  First, both the semitendinosus and gracilis muscles can actively stabilize the joint against valgus moments in the MCL-deficient knee. Second, the stabilizing influence of these muscles decreases with an increasing knee flexion angle.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  The kinematics was examined in 10 fresh-frozen human cadaveric knees using a robotic/universal force moment sensor system and an optical tracking system. The knee kinematics under 5- and 10-N·m valgus moments were determined in the different flexion angles of the (1) MCL-intact and (2) MCL-deficient knee using the following simulated muscle loads: (1) 0-N (idle) load, (2) 200-N semitendinosus (ST) load, and (3) 280-N (200/80-N) combined semitendinosus/gracilis (STGT) load.
  
  
  RESULTS
  Cutting the MCL increased the valgus angle under all tested conditions and angles compared with the MCL-intact knee by 4.3° to 8.1° for the 5-N·m valgus moment and 6.5° to 11.9° for the 10-N·m valgus moment ( P < .01). The applied 200-N simulated ST load reduced the valgus angle significantly at 0°, 10°, 20°, and 30° of flexion under 5- and 10-N·m valgus moments ( P < .05). At 0°, 10°, and 20° of flexion, these values were close to those for the MCL-intact joint under the respective moments (both P > .05). The combined 280-N simulated STGT load significantly reduced the valgus angle in 0°, 10°, and 20° of flexion under 5- and 10-N·m valgus moments ( P < .05) to values near those for the intact joint (5 N·m: 0°, 10°; 10 N·m: 0°, 10°, 20°; P > .05). In 60° and 90° of flexion, ST and STGT loads did not decrease the resulting valgus angle of the MCL-deficient knee without hamstring loads ( P > .05 vs deficient; P = .0001 vs intact).
  
  
  CONCLUSIONS
  In this human cadaveric study, semitendinosus and gracilis muscles successfully stabilize valgus moments applied to the MCL-insufficient knee when the knee is near extension.
  
  
  CONCLUSIONS
  In the valgus-unstable knee, these data suggest that the hamstring muscles should be preserved in (multi-) ligament surgery when possible.
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, Westphalian Wilhelms University Muenster, Muenster, Germany.
authors.forename: Mirco
authors.initials: M
authors.lastname: Herbort
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, Westphalian Wilhelms University Muenster, Muenster, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Michel
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, Westphalian Wilhelms University Muenster, Muenster, Germany.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Raschke
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, Westphalian Wilhelms University Muenster, Muenster, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Vogel
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, Westphalian Wilhelms University Muenster, Muenster, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Schulze
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, Westphalian Wilhelms University Muenster, Muenster, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Zoll
authors.affiliation: Research Unit for Orthopedic Sports Medicine and Injury Prevention, Institute of Sports and Alpine Medicine, University of Hall in Tirol, Tirol, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Fink
authors.affiliation: Department of Orthopedic and Trauma Surgery, Martin Luther Hospital, Berlin, Germany.
authors.forename: Wolf
authors.initials: W
authors.lastname: Petersen
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, Westphalian Wilhelms University Muenster, Muenster, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Domnick
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D059549:Anterior Cruciate Ligament Reconstruction; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D000070633:Hamstring Muscles / Q000601:surgery*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D017888:Medial Collateral Ligament, Knee / Q000503:physiopathology*; D008875:Middle Aged; D016059:Range of Motion, Articular
keywords: ACL reconstruction; hamstrings; medial collateral ligament; robotics; semitendinosus