title: Arthroscopic treatment of solitary benign intra-articular lesions of the knee that cause mechanical symptoms.
abstract: OBJECTIVE
  Most cases of knee locking and giving-way are caused by meniscal tears, loose bodies, or chondral lesions. Intra-articular benign tumors or tumor-like lesions can present with symptoms that resemble acute mechanical derangement. From a database of 2,200 arthroscopic interventions, 19 cases of intra-articular masses that presented with catching and locking symptoms in the knee were retrospectively analyzed.
  
  
  METHODS
  Case series.
  
  
  METHODS
  Our review revealed 33 patients with benign intra-articular masses in the knee joint. Nineteen of these individuals had sought medical attention for mechanical symptoms of catching or locking. The other 14 patients had a variety of symptoms including pain, swelling, and limitation of knee motion, but did not have mechanical symptoms. Age, sex, history of trauma, knee pain and effusion, medical illnesses, physical examination, arthroscopic findings, and pathologic findings were noted.
  
  
  RESULTS
  The average age of the 6 male and 13 female patients was 37.5 years (range, 18 to 58 years). Preoperative magnetic resonance imaging confirmed the diagnosis in 7 cases and 12 cases were diagnosed during knee arthroscopy. The mean follow-up time after surgery was 52.5 months (range, 6 to 120 months). Pathologic examination of the lesions revealed 15 cases of localized pigmented villonodular synovitis (79%), 1 lipoma arborescens (5%), 1 pseudocyst (5%), and 2 nonspecific synovial masses (11%). None of the lesions showed malignant transformation.
  
  
  CONCLUSIONS
  Solitary benign intra-articular lesions should be considered a rare cause of mechanical knee symptoms. Localized pigmented villonodular synovitis originating from the extensor mechanism or fat pad is the most common solitary intra-articular mass lesion in the knee and usually arises in the patellofemoral compartment. Recurrence has not occurred in our series, which includes 14 of 19 patients with greater than 24 months follow-up.
  
  
  METHODS
  Level IV.
authors.affiliation: Baskent University Faculty of Medicine, Department of Orthopaedics and Traumatology, Adana Medical Center, Adana, Turkey. mozalay@hotmail.com
authors.forename: Metin
authors.initials: M
authors.lastname: Ozalay
authors.forename: Reha N
authors.initials: RN
authors.lastname: Tandoğan
authors.forename: Sercan
authors.initials: S
authors.lastname: Akpinar
authors.forename: Necip
authors.initials: N
authors.lastname: Cesur
authors.forename: Murat Ali
authors.initials: MA
authors.lastname: Hersekli
authors.forename: Gürkan
authors.initials: G
authors.lastname: Ozkoç
authors.forename: Mustafa
authors.initials: M
authors.lastname: Uysal
mesh_terms: D000293:Adolescent; D000328:Adult; D001182:Arthroscopy; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007592:Joint Diseases / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D007719:Knee Joint / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies