title: Prevalence of Lateral Meniscal Extrusion for Posterior Lateral Meniscal Root Lesion With and Without Concomitant Midbody Radial Tear in Anterior Cruciate Ligament Injury.
abstract: To investigate the prevalence of lateral meniscal extrusion for patients with posterior lateral meniscal root lesions (PLMRLs) and for those with concomitant midbody radial tears (MRTs) in anterior cruciate ligament (ACL) injuries.
  
  
  
  A database of consecutive patients undergoing primary ACL reconstruction between 2011 and 2013 was retrospectively reviewed to identify patients with isolated ACL injuries and those with associated PLMRLs. Patients with (1) unavailable preoperative magnetic resonance imaging scans, (2) other concomitant ligamentous injuries, (3) severe degeneration or malalignment, (4) infection or tumor, or (5) history of surgery on the injured side were excluded. For patients with associated PLMRLs (study group), degree of concomitant MRTs and status of meniscofemoral ligaments (MFLs) were verified arthroscopically. Prevalence of lateral meniscal extrusion was compared between (1) patients in the study group and those with isolated ACL injuries and between (2) those with and without concomitant MRTs in the study group.
  
  
  
  Of the 1,021 consecutive patients, 412 met the inclusion and exclusion criteria. Of those, 52 (5.1%) had an associated PLMRL (study group) and another 52 were randomly chosen from the 360 isolated ACL injuries as the control group. In the study group, 33 (63.5%) were arthroscopically verified to have concomitant MRTs. Prevalence of lateral meniscal extrusion was significantly higher (P < .0001) in the study group (30.8%; 95% confidence interval [CI], 18.3 to 43.3) than in the control group (1.9%; 95% CI, -1.8 to 5.6), whereas there was no significant difference (P = .758) between patients with (33.3%; 95% CI, 17.3 to 49.3) and without (26.3%; 95% CI, 6.5 to 46.1) concomitant MRTs in the study group. However, the 7 patients who showed either complete concomitant MRTs or absence of MFLs were all diagnosed to have lateral meniscal extrusion.
  
  
  
  The PLMRLs, identified in 5.1% of ACL injuries, appeared to result in lateral meniscal extrusion. Although the presence of a concomitant MRT did not further increase the prevalence of lateral meniscal extrusion in the setting of a PLMRL, surgical repair might still be necessary if a complete concomitant MRT or an absence of MFL was identified to restore normal meniscal functions.
  
  
  
  Level III, prognostic case-control study.
authors.affiliation: Sports Medicine Service, Beijing Jishuitan Hospital, Beijing, People's Republic of China.
authors.forename: Jie-Wei
authors.initials: JW
authors.lastname: Shen
authors.affiliation: Sports Medicine Service, Beijing Jishuitan Hospital, Beijing, People's Republic of China.
authors.forename: Guan-Yang
authors.initials: GY
authors.lastname: Song
authors.affiliation: Sports Medicine Service, Beijing Jishuitan Hospital, Beijing, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Clinical Research and Evidence-Based Medicine Center, Beijing Institute of Traumatology and Orthopaedics, Beijing Jishuitan Hospital, Beijing, People's Republic of China.
authors.forename: Qian-Qian
authors.initials: QQ
authors.lastname: Wang
authors.affiliation: Sports Medicine Service, Beijing Jishuitan Hospital, Beijing, People's Republic of China.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Sports Medicine Service, Beijing Jishuitan Hospital, Beijing, People's Republic of China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Li
authors.affiliation: Sports Medicine Service, Beijing Jishuitan Hospital, Beijing, People's Republic of China. Electronic address: fenghua20080617@126.com.
authors.forename: Hua
authors.initials: H
authors.lastname: Feng
mesh_terms: D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries / Q000150:complications* / Q000000981:diagnostic imaging; D001182:Arthroscopy; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D012189:Retrospective Studies; D000070600:Tibial Meniscus Injuries / Q000150:complications* / Q000000981:diagnostic imaging