title: Second-look arthroscopic assessment of cartilage regeneration after medial opening-wedge high tibial osteotomy.
abstract: OBJECTIVE
  The purposes of this study were to evaluate regeneration of the articular cartilage after medial opening-wedge high tibial osteotomy for knees with medial-compartment osteoarthritis and to assess the clinical outcome and cartilage regeneration according to the postoperative limb alignment at 2 years postoperatively.
  
  
  METHODS
  The study involved 159 knees in 159 patients. For evaluation of cartilage degeneration, the International Cartilage Repair Society grading system was used for arthroscopic grading on initial arthroscopy during high tibial osteotomy. The patients underwent a second-look arthroscopic evaluation of the articular cartilage at the time of removal of the plate, an average of 2 years after the initial osteotomy. For evaluation of cartilage regeneration, the articular cartilage was classified into 2 stages as no regenerative change (grade 1) or white scattering with fibrocartilage, partial coverage with fibrocartilage, or even coverage with fibrocartilage (grade 2) on second-look arthroscopy. Maturation of the cartilage regeneration was defined as even coverage with fibrocartilage. "Immaturation" of the cartilage regeneration was defined as white scattering with fibrocartilage or partial coverage with fibrocartilage. Clinical evaluations were performed by use of Knee Society scores preoperatively and at 2 years postoperatively. We divided the knees into 3 groups according to the postoperative limb alignment. Group A comprised knees with a mechanical tibiofemoral angle of 0° or less. Group B comprised knees with a mechanical tibiofemoral angle greater than 0° and less than 6°. Group C comprised knees with a mechanical tibiofemoral angle of 6° or greater.
  
  
  RESULTS
  Grade 2 regeneration was achieved in the medial femoral condyle articular cartilage in 92% of knees and in the medial tibial plateau articular cartilage in 69% of knees. Maturation of the cartilage regeneration was found in the medial femoral condyle articular cartilage in 4% of knees and in the medial tibial plateau articular cartilage in 1% of knees. At follow-up, no significant differences were seen between clinical outcomes and initial cartilage degeneration (P = .338) or cartilage regeneration (P = .699). Regeneration of the medial femoral condyle articular cartilage was found in 75% of group A knees, 95% of group B knees, and 92% of group C knees. Significant differences were seen between cartilage regeneration and clinical outcomes (P = .001), as well as postoperative limb alignment (P = .018). Clinical and regeneration results were better in group B than in groups A and C.
  
  
  CONCLUSIONS
  The degenerated cartilage of the medial femoral condyle and medial tibial plateau could be partially or entirely covered by newly regenerated cartilage at 2 years after adequate correction of varus deformity by medial opening-wedge high tibial osteotomy without cartilage regeneration strategies.
  
  
  METHODS
  Level IV, therapeutic case series.
authors.affiliation: Department of Orthopedic Surgery, Murup Hospital, Gyeongnam, South Korea.
authors.forename: Woon-Hwa
authors.initials: WH
authors.lastname: Jung
authors.affiliation: Yokosuka Municipal Hospital, Kanagawa, Japan.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Takeuchi
authors.affiliation: Department of Orthopedic Surgery, Murup Hospital, Gyeongnam, South Korea.
authors.forename: Chung-Woo
authors.initials: CW
authors.lastname: Chun
authors.affiliation: Department of Orthopedic Surgery, Murup Hospital, Gyeongnam, South Korea.
authors.forename: Jung-Su
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Department of Orthopedic Surgery, Murup Hospital, Gyeongnam, South Korea.
authors.forename: Jae-Hun
authors.initials: JH
authors.lastname: Ha
authors.affiliation: Department of Orthopedic Surgery, Murup Hospital, Gyeongnam, South Korea.
authors.forename: Ji-Hyae
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Orthopedic Surgery, Murup Hospital, Gyeongnam, South Korea. Electronic address: osjjaeheon@naver.com.
authors.forename: Jae-Heon
authors.initials: JH
authors.lastname: Jeong
mesh_terms: D001182:Arthroscopy / Q000379:methods*; D002358:Cartilage, Articular / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000503:physiopathology; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D010027:Osteotomy; D011859:Radiography; D016059:Range of Motion, Articular; D012038:Regeneration; D012189:Retrospective Studies; D024162:Second-Look Surgery / Q000379:methods*; D013977:Tibia / Q000000981:diagnostic imaging / Q000503:physiopathology; D013997:Time Factors