title: In vitro biomechanical study of femoral torsion disorders: effect on moment arms of thigh muscles.
abstract: BACKGROUND
  Lower limb torsion disorders have been considered as a factor inducing gonarthrosis and the three-dimensional effect of the surgical correction is not well reported yet. This paper reports an in vitro study aiming at quantifying the relationships between experimental femoral torsion disorders and moment arms of thigh muscles.
  
  
  METHODS
  Five unembalmed lower limbs were used and fixed on an experimental jig. Muscles were loaded and 6 Linear Variable Differential Transformers were used to measure tendon excursions. Experimental osteotomies were performed to simulate torsions by steps of 6° up to 18°. Moment arms of the main thigh muscles were estimated by the tendon excursion method during knee flexion.
  
  
  RESULTS
  Moment arms of the tensor of fascia latae, the gracilis and the semitendinosus were significantly influenced by experimental conditions while the rectus femoris, the biceps femoris and the semimembranosus did not show modifications. Medial femoral torsion decreased the moment arm of both the gracilis and the semimembranosus. Opposite changes were observed during lateral femoral torsion. The moment arm of the tensor of fascia latae decreased significantly after 30° of knee flexion for 18° of medial femoral torsion.
  
  
  CONCLUSIONS
  Our results showed that medial and lateral femoral torsion disorders induced alterations of the moment arms of the muscles located medially to the knee joint when applied in aligned lower limbs. These results highlight a potential clinical relevance of the effect of femoral torsion alterations on moment arms of muscles of the thigh which may be related, with knee kinematics modifications, to the development of long-term knee disease.
authors: Laboratory of Anatomy, Biomechanics and Organogenesis, Faculté de Médicine, Université Libre de Bruxelles, Bruxelles, Belgium. ssobczak@ulb.ac.be
authors: S
authors: S
authors: Sobczak
authors: P-M
authors: PM
authors: Dugailly
authors: V
authors: V
authors: Feipel
authors: B
authors: B
authors: Baillon
authors: M
authors: M
authors: Rooze
authors: P
authors: P
authors: Salvia
authors: S
authors: S
authors: Van Sint Jan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology*; D020370:Osteoarthritis, Knee / Q000209:etiology*; D013848:Thigh; D014102:Torsion Abnormality / Q000150:complications* / Q000503:physiopathology