title: MR imaging of post-traumatic articular cartilage injuries confined to the femoral trochlea. Arthroscopic correlation and clinical significance.
abstract: OBJECTIVE
  To assess and describe post-traumatic articular cartilage injuries isolated to the trochlear groove and provide insight into potential mechanism of injury.
  
  
  METHODS
  We retrospectively evaluated MR imaging findings of all knee MRIs performed at our institution over the last 2 years (2450). Thirty patients met the criteria of a cartilage injury confined to the trochlear groove. In 15 cases, which were included in our study, arthroscopic correlation was available. Each plane was evaluated and graded for the presence and appearance of articular cartilage defects using a standard arthroscopic grading scheme adapted to MR imaging. Any additional pathological derangement was documented and information about the mechanism of injury was retrieved by chart review.
  
  
  RESULTS
  In all cases the cartilaginous injury was well demonstrated on MRI. In 13 patients additional pathological findings could be observed. The most frequently associated injury was a meniscal tear in nine patients. In eight cases, the arthroscopic grading of the trochlear injury matched exactly with the MRI findings. In the remaining seven cases, the discrepancy between MRI and arthroscopy was never higher than one grade. In 13 out of 15 of patients trauma mechanism could be evaluated. Twelve patients suffered an indirect twisting injury and one suffered a direct trauma to their knee.
  
  
  CONCLUSIONS
  The findings of this study demonstrate that MR imaging allows reliable grading of isolated injury to the trochlear groove cartilage and assists in directing surgical diagnosis and treatment. These injuries may be the only hyaline cartilage injury in the knee and meniscal tears are a frequently associated finding. Therefore, it is important to search specifically for cartilage injuries of the trochlear groove in patients with anterior knee pain, even if other coexistent pathology could potentially explain the patient's symptoms.
authors.affiliation: Department of Radiology, University Hospital of Basel, Petersgraben 4, Basel 4031, Switzerland. rhuegli@uhbs.ch
authors.forename: Rolf W
authors.initials: RW
authors.lastname: Huegli
authors.forename: Sonja M C
authors.initials: SM
authors.lastname: Moelleken
authors.forename: Alexander
authors.initials: A
authors.lastname: Stork
authors.forename: Harald M
authors.initials: HM
authors.lastname: Bonel
authors.forename: Miriam A
authors.initials: MA
authors.lastname: Bredella
authors.forename: Stephan
authors.initials: S
authors.lastname: Meckel
authors.forename: Harry K
authors.initials: HK
authors.lastname: Genant
authors.forename: Phillip F J
authors.initials: PF
authors.lastname: Tirman
mesh_terms: D000293:Adolescent; D000328:Adult; D001182:Arthroscopy; D002358:Cartilage, Articular / Q000293:injuries*; D005260:Female; D005269:Femur / Q000293:injuries*; D006801:Humans; D006818:Hyalin; D007718:Knee Injuries / Q000145:classification / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015642:Radiology, Interventional; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012421:Rupture; D000070600:Tibial Meniscus Injuries