title: Asymmetric knee loading in advanced unilateral hip osteoarthritis.
abstract: OBJECTIVE
  Subjects with unilateral end-stage hip osteoarthritis (OA) who undergo total hip replacement (THR) preferentially require subsequent replacement of the contralateral knee compared with the ipsilateral knee. We investigated whether this nonrandom, preferential evolution of lower extremity OA from the hip to the contralateral knee joint may be related to asymmetries in dynamic joint loading at the knees, particularly the peak external knee adduction moment, which has been associated with the progression of knee OA.
  
  
  METHODS
  Gait analysis was performed on 50 subjects who were preoperative for unilateral THR. Twenty-two of these subjects were reevaluated postoperatively 10-23 months after undergoing successful THR. At each analysis, dynamic joint loads in the contralateral knee were compared with those in the ipsilateral knee.
  
  
  RESULTS
  Prior to THR, the peak external knee adduction moment and peak medial compartment load were significantly higher in the contralateral knee. This asymmetry persisted after THR.
  
  
  CONCLUSIONS
  Subjects with unilateral end-stage hip OA preferentially require subsequent replacement of the contralateral knee, as compared with the ipsilateral knee. Among patients with unilateral end-stage hip OA, the contralateral knee is subjected to higher dynamic joint loads than is the ipsilateral knee, and this asymmetric loading persists long after subjects have undergone successful THR. Biomechanical factors appear to be involved in the multiarticular evolution of OA of the lower extremities.
authors.affiliation: Section of Rheumatology, Rush Medical College, Chicago, Illinois 60612-3862, USA. naja_shakoor@rush.edu
authors.forename: Najia
authors.initials: N
authors.lastname: Shakoor
authors.forename: Debra E
authors.initials: DE
authors.lastname: Hurwitz
authors.forename: Joel A
authors.initials: JA
authors.lastname: Block
authors.forename: Susan
authors.initials: S
authors.lastname: Shott
authors.forename: John P
authors.initials: JP
authors.lastname: Case
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects; D018450:Disease Progression; D005260:Female; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000503:physiopathology* / Q000601:surgery; D020370:Osteoarthritis, Knee / Q000209:etiology / Q000503:physiopathology*; D011183:Postoperative Complications; D016474:Weight-Bearing