title: Effect of soft tissue laxity of the knee joint on limb alignment correction in open-wedge high tibial osteotomy.
abstract: OBJECTIVE
  Open-wedge high tibial osteotomy (HTO) cannot always accurately correct limb alignment, resulting in under- or over-correction. This study assessed the relationship between soft tissue laxity of the knee joint and alignment correction in open-wedge HTO.
  
  
  METHODS
  This prospective study involved 85 patients (86 knees) undergoing open-wedge HTO for primary medial osteoarthritis. The mechanical axis (MA), weight-bearing line (WBL) ratio, and joint line convergence angle (JLCA) were measured on radiographs preoperatively and after 6 months, and the differences between the pre- and post-surgery values were calculated. Post-operative WBL ratios of 57-67 % were classified as acceptable correction. WBL ratios <57 and >67 % were classified as under- and over-corrections, respectively.
  
  
  RESULTS
  Preoperative JLCA correlated positively with differences in MA (r = 0.358, P = 0.001) and WBL ratio (P = 0.003). Difference in JLCA showed a stronger correlation than preoperative JLCA with differences in MA (P < 0.001) and WBL ratio (P < 0.001). Difference in JLCA was the only predictor of both difference in MA (P < 0.001) and difference in WBL ratio (P < 0.001). The difference between pre- and post-operative JLCA differed significantly between the under-correction, acceptable-correction, and over-correction groups (P = 0.033). Preoperative JLCA, however, did not differ significantly between the three groups. Neither preoperative JLCA nor difference in JLCA correlated with change in posterior slope.
  
  
  CONCLUSIONS
  Preoperative degree of soft tissue laxity in the knee joint was related to the degree of alignment correction, but not to alignment correction error, in open-wedge HTO. Change in soft tissue laxity around the knee from before to after open-wedge HTO correlated with both correction amount and correction error. Therefore, a too large change in JLCA from before to after open-wedge osteotomy may be due to an overly large reduction in JLCA following osteotomy, suggesting alignment over-correction during surgery.
  
  
  METHODS
  II.
authors.affiliation: Department of Orthopaedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Dae-Hee
authors.initials: DH
authors.lastname: Lee
authors.affiliation: Department of Orthopaedic Surgery, Anam Hospital, Korea University School of Medicine, 126-1, Anam-dong 5-ga, Seongbuk-gu, Seoul, 136-705, Republic of Korea.
authors.forename: Sung-Chul
authors.initials: SC
authors.lastname: Park
authors.affiliation: Department of Orthopaedic Surgery, Anam Hospital, Korea University School of Medicine, 126-1, Anam-dong 5-ga, Seongbuk-gu, Seoul, 136-705, Republic of Korea.
authors.forename: Hyung-Joon
authors.initials: HJ
authors.lastname: Park
authors.affiliation: Department of Orthopaedic Surgery, Anam Hospital, Korea University School of Medicine, 126-1, Anam-dong 5-ga, Seongbuk-gu, Seoul, 136-705, Republic of Korea. oshan@korea.ac.kr.
authors.forename: Seung-Beom
authors.initials: SB
authors.lastname: Han
mesh_terms: D000328:Adult; D000368:Aged; D017760:Bone Malalignment / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D010027:Osteotomy / Q000379:methods*; D011184:Postoperative Period; D011446:Prospective Studies; D011859:Radiography; D013977:Tibia / Q000601:surgery*; D016896:Treatment Outcome; D016474:Weight-Bearing
keywords: Alignment correction; High tibial osteotomy; Joint line convergence angle