Factors affecting cartilage repair after medial opening-wedge high tibial osteotomy.
PURPOSE
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.


CONCLUSION
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.


LEVEL OF EVIDENCE
Level IV, therapeutic case series.
['Kumagai|Ken|K|', 'Akamatsu|Yasushi|Y|', 'Kobayashi|Hideo|H|', 'Kusayama|Yoshihiro|Y|', 'Koshino|Tomihisa|T|', 'Saito|Tomoyuki|T|']
D000368:Aged D001182:Arthroscopy D002358:Cartilage, Articular D005260:Female D005269:Femur D006801:Humans D007719:Knee Joint D008297:Male D020370:Osteoarthritis, Knee D010027:Osteotomy D012038:Regeneration D024162:Second-Look Surgery D013977:Tibia D014945:Wound Healing
Opening-wedge High tibial osteotomy Knee Cartilage regeneration