title: The anterior cruciate ligament remnant: to leave it or not?
abstract: OBJECTIVE
  The role of the anterior cruciate ligament remnant in anterior cruciate ligament reconstruction (ACLR) is debated. The purposes of this systematic review were (1) to summarize the clinical outcomes of patients undergoing remnant-preserving ACLR and (2) to investigate whether those outcomes were superior to standard ACLR.
  
  
  METHODS
  The PubMed database was searched using specific inclusion and exclusion criteria for clinical studies reporting both preoperative conditions and postoperative outcomes of remnant-preserving ACLR. All reported postoperative complications were analyzed. In addition, a modified Coleman Methodology Score (CMS) system was used to assess the methodologic quality of the included studies.
  
  
  RESULTS
  Thirteen studies were included with a mean CMS value of 71.7 (range, 57 to 92). In total, 546 patients underwent remnant-preserving ACLR by 3 different procedures: standard ACLR plus tibial remnant tensioning (n = 166), selective-bundle augmentation (n = 337), and standard ACLR plus tibial remnant sparing (n = 43). All clinical outcomes improved significantly (P < .05) at the final follow-up (mean, 27.9 months). Seven studies directly compared postoperative clinical outcomes between remnant-preserving ACLR and standard ACLR. In 6 of the 7 studies, similar postoperative clinical outcomes were reported between groups. One study reported superior clinical outcomes after remnant-preserving ACLR. There was no significant difference between groups regarding the overall rate of postoperative complications.
  
  
  CONCLUSIONS
  The mean CMS showed moderate methodologic quality for the included studies. This systematic review showed significant postoperative improvements in patients undergoing remnant-preserving ACLR in all of the studies. However, further comparisons between remnant-preserving ACLR and standard ACLR showed inconsistent results in the 7 comparative studies, with 6 reporting equivalent postoperative clinical outcomes between groups. There was no significant difference in the rate of total complications between groups. The currently available evidence is not sufficiently strong to support the superiority of remnant-preserving ACLR.
  
  
  METHODS
  Level IV, systematic review of Level I-IV studies.
authors.affiliation: Sports Medicine Service, Beijing Jishuitan Hospital, Beijing, China.
authors.forename: Guan-Yang
authors.initials: GY
authors.lastname: Song
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.forename: Jin
authors.initials: J
authors.lastname: Zhang
authors.forename: Xu
authors.initials: X
authors.lastname: Li
authors.forename: Xing-Zuo
authors.initials: XZ
authors.lastname: Chen
authors.forename: Yue
authors.initials: Y
authors.lastname: Li
authors.forename: Hua
authors.initials: H
authors.lastname: Feng
mesh_terms: D016118:Anterior Cruciate Ligament / Q000601:surgery*; D059549:Anterior Cruciate Ligament Reconstruction / Q000009:adverse effects / Q000379:methods*; D001182:Arthroscopy / Q000379:methods; D006801:Humans; D059351:Organ Sparing Treatments / Q000379:methods*; D013977:Tibia / Q000601:surgery; D016896:Treatment Outcome