title: Meniscal extrusion and spontaneous osteonecrosis with root tear of medial meniscus: comparison with horizontal tear.
abstract: OBJECTIVE
  The incidence of root tears in patients with spontaneous osteonecrosis of the knee has been studied, but the incidence of spontaneous osteonecrosis of the knee in patients with medial meniscus root tears has not. We assessed the latter incidence and evaluated the characteristics of medial meniscus root tears by comparing clinical status, the degree of osteonecrosis, and meniscal extrusion in patients with horizontal tears.
  
  
  METHODS
  Sixty-three patients who were diagnosed with medial meniscus posterior horn tear and treated by arthroscopic surgery between March 2005 and March 2009 were evaluated retrospectively. Patients were divided into 2 groups, the root tear group (R group) and the horizontal tear group (H group). Functional scores and radiography, simple radiography, and magnetic resonance imaging were investigated.
  
  
  RESULTS
  No significant differences in age, body mass index, and symptom duration were observed between the 2 groups. The incidence of osteonecrosis was 12 of 36 knees (33.3%) in the R group and 4 of 27 (14.8%) in the H group. The mean absolute extrusion was 4.1 ± 0.7 mm and 3.5 ± 1.4 mm in the R and H groups, respectively (P = not significant). The mean relative percentage of extrusion in the R group (46.1% ± 9.0%) was greater than that in the H group (35.3% ± 13.2%) (P = .01). The degree of osteonecrosis (ellipsoidal volume) was also greater in the R group (423.1 ± 236.7 mm(3)) than that in the H group (175.8 ± 43.6 mm(3)) (P = .03). Though not significant, the visual analog pain score had a tendency to be more severe and knee scores had a tendency to be lower in the R group than in the H group.
  
  
  CONCLUSIONS
  Medial meniscus root tears had a greater degree of meniscal extrusion and wider osteonecrosis than horizontal tears of the posterior horn related to loss of the main function of the meniscus.
  
  
  METHODS
  Level III, retrospective comparative study.
authors: Sports Medical Center, Department of Orthopedic Surgery, Seoul Paik Hospital, University of Inje College of Medicine, Seoul, South Korea.
authors: Jung Hwan
authors: JH
authors: Sung
authors: Jeong Ku
authors: JK
authors: Ha
authors: Dhong Won
authors: DW
authors: Lee
authors: Won Yeong
authors: WY
authors: Seo
authors: Jin Goo
authors: JG
authors: Kim
mesh_terms: D000328:Adult; D000368:Aged; D001182:Arthroscopy; D005260:Female; D005269:Femur / Q000473:pathology*; D006801:Humans; D015994:Incidence; D007718:Knee Injuries / Q000150:complications / Q000175:diagnosis*; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010020:Osteonecrosis / Q000175:diagnosis* / Q000209:etiology; D012189:Retrospective Studies; D000070600:Tibial Meniscus Injuries