title: The role of the deep medial collateral ligament in controlling rotational stability of the knee.
abstract: OBJECTIVE
  The tibial insertion of the deep medial collateral ligament (dMCL) is frequently sacrificed when the proximal tibial cut is performed during total knee arthroplasty. The role of the dMCL in controlling the knee's rotational stability is still controversial. The aim of this study was to quantify the rotational laxity induced by an isolated lesion of the dMCL as it occurs during tibial preparation for knee arthroplasty.
  
  
  METHODS
  An isolated resection of the deep MCL was performed in 10 fresh-frozen cadaver knees. Rotational laxity was measured during application of a standard 5.0 N.m rotational torque. Maximal tibial rotation was measured at different knee flexion angles using an image-guided navigation system (Medivision Surgetics system, Praxim, Grenoble, France) before and after dMCL resection.
  
  
  RESULTS
  In all cases, internal and external tibial rotation increased after dMCL resection. Total rotational laxity increased significantly for all knee flexion angles, with an average difference of +7.8° (SD 5.7) with the knee in extension, +8.9° (SD 1.9) in 30° flexion, +7° (SD 2.9) in 60° flexion and +5.3° (SD 2.8) in 90° flexion.
  
  
  CONCLUSIONS
  Sacrificing the tibial insertion of the deep MCL increases rotational laxity of the knee by 5°-9°, depending on the knee flexion angle. Based on our findings, new surgical techniques and implants that preserve the dMCL insertion such as tibial inlay components should be developed. Further clinical evaluations are necessary.
authors.affiliation: Institut de l'appareil locomoteur, CHU Rangueil, 1, Avenue Jean Poulhès TSA 50032, 31059, Toulouse Cedex 9, France. cavaignac.etienne@gmail.com.
authors.forename: Etienne
authors.initials: E
authors.lastname: Cavaignac
authors.affiliation: Department of Orthopedic Surgery and Traumatology, University Hospitals Leuven, Louvain, Belgium.
authors.forename: Karel
authors.initials: K
authors.lastname: Carpentier
authors.affiliation: Institut de l'appareil locomoteur, CHU Rangueil, 1, Avenue Jean Poulhès TSA 50032, 31059, Toulouse Cedex 9, France.
authors.forename: Regis
authors.initials: R
authors.lastname: Pailhé
authors.affiliation: Department of Orthopedic Surgery and Traumatology, University Hospitals Leuven, Louvain, Belgium.
authors.forename: Thomas
authors.initials: T
authors.lastname: Luyckx
authors.affiliation: Department of Orthopedic Surgery and Traumatology, University Hospitals Leuven, Louvain, Belgium.
authors.forename: Johan
authors.initials: J
authors.lastname: Bellemans
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee; D001696:Biomechanical Phenomena; D002102:Cadaver; D017885:Collateral Ligaments / Q000601:surgery*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery; D007720:Knee Prosthesis; D008297:Male; D016059:Range of Motion, Articular
keywords: Deep MCL; Inlay technique; Knee prosthesis; Rotational stability