title: Effect of the lower limb rotational alignment on tibiofemoral contact pressure.
abstract: OBJECTIVE
  The effect of the rotational alignment of lower extremities on the tibiofemoral contact mechanics is not known. This study was designed to measure the contact area and pressure within medial and lateral tibiofemoral compartments following controlled serial rotational deformities through femoral and tibial shafts.
  
  
  METHODS
  Eight lower extremities of fresh frozen cadavers were used. Computed tomography was conducted to measure the rotational profile of the lower extremities. Through a medial parapatellar arthrotomy, pressure sensors were implanted into both tibiofemoral compartments. Femoral and tibial mid-shaft osteotomies were performed and stabilized by non-locked intramedullary nails and external fixators in neutral rotation. The contact area and pressure were measured under axial loading in neutral rotation and following serial malrotations from 40° external to 40° internal malrotation in 10° increments.
  
  
  RESULTS
  Contact area was not affected by malrotations. Medial compartment contact pressure rose with external and decreased with internal malrotations whether femoral or tibial (P < 0.0001) while lateral pressure was not affected. When correlated with the cadavers' original rotational profile, decreased femoral neck anteversion was associated with increased medial pressure up to 28.5% at 20° of retroversion while it decreased with increased anteversion. On the other hand, decreased tibial torsion angle was associated with decreased medial pressure up to -32% at 10° of internal torsion and it increased with excessive external torsion. Furthermore, there was a strong positive correlation with the total rotational alignment as measured by the neck malleolar angle.
  
  
  CONCLUSIONS
  A significant interaction could be detected between the rotational alignment of the lower extremity and medial tibiofemoral compartment contact pressures.
authors: Trauma Department, Hannover Medical School, Carl-Neuberg-Street 1, 30625 Hannover, Germany. mohamed_kenawey@yahoo.com
authors: Mohamed
authors: M
authors: Kenawey
authors: Emmanouil
authors: E
authors: Liodakis
authors: Christian
authors: C
authors: Krettek
authors: Sven
authors: S
authors: Ostermeier
authors: Tatiana
authors: T
authors: Horn
authors: Stefan
authors: S
authors: Hankemeier
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D001858:Bone Nails; D002102:Cadaver; D016267:External Fixators; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging* / Q000601:surgery; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D010027:Osteotomy; D011312:Pressure; D012399:Rotation; D013314:Stress, Mechanical; D013977:Tibia / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed