title: Cartilage MRI relaxation times after arthroscopic partial medial meniscectomy reveal localized degeneration.
abstract: OBJECTIVE
  Little is known about the early changes in cartilage composition and tibiofemoral kinematics following partial meniscectomy. The purpose of this study was to determine the effects of partial meniscectomy on cartilage compositional properties using T1ρ and T2 relaxation time mapping and to assess changes in tibiofemoral kinematics. It is hypothesize that abnormal tibiofemoral kinematics and relaxation time elevation (a reflection of changes in cartilage biochemical composition) in the weight-bearing regions of the knees following meniscectomy will be observed.
  
  
  METHODS
  Nine patients (7 males and 2 females; mean age, 48.6 ± 10.8 years; BMI = 27.3 ± 3.8 kg/m(2)) with tears of the posterior horn of the medial meniscus underwent arthroscopic partial meniscectomy. Pre-surgical and 6 months post-surgical MRIs were obtained in all subjects to evaluate cartilage relaxation times and tibiofemoral kinematics. Paired t tests were performed to determine significant changes in cartilage relaxation times from baseline.
  
  
  RESULTS
  T1ρ relaxation time in the region of the medial femoral condyle directly adjacent to the resection showed an increase of 7.4% at 6 months (p = 0.02). T2 relaxation times in both the medial and lateral tibial plateaus showed significant elevation at 6 months. Consistent kinematic trends were not found in post-meniscectomized knees.
  
  
  CONCLUSIONS
  These results suggest that arthroscopic partial meniscectomy affects the biochemical composition of articular cartilage in the knee in as early as 6 months. The largest responses were observed in the weight-bearing regions and the cartilage immediately adjacent to the resection. This suggests that the loading environment has been altered enough to result in cartilage compositional changes in a very brief period of time following meniscectomy.
  
  
  METHODS
  IV.
authors.affiliation: Department of Physical Therapy and Rehabilitation Science, University of California San Francisco, 185 Berry Street, Suite 350, San Francisco, CA, 94107, USA, richard.souza@ucsf.edu.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Souza
authors.forename: Samuel J
authors.initials: SJ
authors.lastname: Wu
authors.forename: Lee Jae
authors.initials: LJ
authors.lastname: Morse
authors.forename: K
authors.initials: K
authors.lastname: Subburaj
authors.forename: Christina R
authors.initials: CR
authors.lastname: Allen
authors.forename: Brian T
authors.initials: BT
authors.lastname: Feeley
mesh_terms: D000328:Adult; D001182:Arthroscopy; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000503:physiopathology*; D005260:Female; D005269:Femur / Q000503:physiopathology; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008592:Menisci, Tibial / Q000503:physiopathology / Q000601:surgery*; D008875:Middle Aged; D013977:Tibia / Q000503:physiopathology