title: Factors affecting cartilage repair after medial opening-wedge high tibial osteotomy.
abstract: OBJECTIVE
  This study documented the healing potential of degenerated articular cartilage after opening-wedge valgus high tibial osteotomy (HTO) in patients with osteoarthritis of the knee. It was hypothesized that regeneration of articular cartilage is affected by several factors, including preoperative cartilage degeneration grade, difference between the medial femoral condyle (MFC) and the medial tibial condyle (MTC), and postoperative knee alignment.
  
  
  METHODS
  Medial opening-wedge valgus HTO was performed in 131 knees of 100 patients (mean age 66 ± 7.7 years). Initial arthroscopy was performed at the time of HTO, and a second-look arthroscopy was performed at the time of plate removal (20.8 ± 6.5 months after HTO). Status of articular cartilage was assessed according to the ICRS grade. Cartilage regeneration was also evaluated by the presence of newly formed cartilaginous tissue. All subjects were followed up postoperatively at 2 years for assessment of clinical and radiographic outcomes.
  
  
  RESULTS
  The number of subjects in ICRS grade 1/2/3/4 was significantly altered from 0/11/53/67 preoperatively to 14/21/56/40 postoperatively in the MFC (P < 0.05) and 0/12/62/57 preoperatively to 9/24/64/34 postoperatively in the MTC (P < 0.05). Newly formed cartilaginous tissue was found in 71 % of MFCs and 51 % of MTCs. Incidence of cartilage regeneration was significantly higher in lower BMI cases, MFC, preoperatively advanced ICRS grade and overcorrected knees. Age, gender and clinical outcomes did not affect cartilage regeneration.
  
  
  CONCLUSIONS
  Cartilage regeneration in degenerated articular cartilage is induced after opening-wedge valgus HTO, which is affected by BMI, the difference between the MFC and MTC, preoperative cartilage degeneration grade, and postoperative limb alignment. Therefore, patient selection by BMI rather than age, and surgical techniques maintaining valgus knee alignment should be considered for cartilage regeneration.
  
  
  METHODS
  Level IV, therapeutic case series.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Yokohama City University Hospital, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004, Japan. kumagai@yokohama-cu.ac.jp.
authors.forename: Ken
authors.initials: K
authors.lastname: Kumagai
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Yokohama City University Hospital, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Akamatsu
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Yokohama City University Hospital, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Kobayashi
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Yokohama City University Hospital, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kusayama
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Yokohama City University Hospital, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004, Japan.
authors.forename: Tomihisa
authors.initials: T
authors.lastname: Koshino
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Yokohama City University Hospital, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Saito
mesh_terms: D000368:Aged; D001182:Arthroscopy; D002358:Cartilage, Articular / Q000601:surgery*; D005260:Female; D005269:Femur / Q000601:surgery; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D008297:Male; D020370:Osteoarthritis, Knee / Q000601:surgery; D010027:Osteotomy / Q000379:methods*; D012038:Regeneration; D024162:Second-Look Surgery; D013977:Tibia / Q000601:surgery*; D014945:Wound Healing
keywords: Cartilage regeneration; High tibial osteotomy; Knee; Opening-wedge