Yasushi Akamatsu1, Satoshi Ohno2, Hideo Kobayashi2, Yoshihiro Kusayama2, Ken Kumagai2, Tomoyuki Saito2. 1. Department of Orthopaedic Surgery, Yokohama City University School of Medicine, Yokohama, Japan. Electronic address: akamatsu@yokohama-cu.ac.jp. 2. Department of Orthopaedic Surgery, Yokohama City University School of Medicine, Yokohama, Japan.
Abstract
BACKGROUND: The coronal subluxation of the proximal tibia relative to the distal femur is a common radiological finding in patients with knee osteoarthritis. The purpose was to evaluate whether the coronal subluxation was corrected after opening wedge high tibial osteotomy (OWHTO), and whether this subluxation was one cause of inconsistency between the actual and predicted alignments (correction loss). METHODS: Fifty-one patients (55 knees) were treated with OWHTO. The change of location between the intersection points of the femoral and tibial axes on the tibial plateau (subluxation-C), the change of location between the lines through the most lateral points of the lateral femoral and tibial condyles (subluxation-L), and joint space angle (JSA) were compared in standing knee radiographs before and one year after OWHTO. The subluxation-C and subluxation-L were converted to a percentage of the tibial plateau width. RESULTS: The mean subluxation-C of 6.5% before OWHTO significantly increased to a mean subluxation-C of 7.3% one year after OWHTO. The mean subluxation-L of 6.3% and JSA of 4.5° before OWHTO significantly decreased to a subluxation-L of 1.8% and JSA of 3.3° one year after OWHTO. The change in subluxation-L correlated with the change in femorotibial angle and correction loss (r=0.634, P<0.001 and r=0.463, P<0.001, respectively). CONCLUSION: The proximal tibia shifted medially relative to the distal femur after OWHTO. This medial shift correlated with the correction loss. The coronal subluxation might be one cause of correction loss.
BACKGROUND: The coronal subluxation of the proximal tibia relative to the distal femur is a common radiological finding in patients with knee osteoarthritis. The purpose was to evaluate whether the coronal subluxation was corrected after opening wedge high tibial osteotomy (OWHTO), and whether this subluxation was one cause of inconsistency between the actual and predicted alignments (correction loss). METHODS: Fifty-one patients (55 knees) were treated with OWHTO. The change of location between the intersection points of the femoral and tibial axes on the tibial plateau (subluxation-C), the change of location between the lines through the most lateral points of the lateral femoral and tibial condyles (subluxation-L), and joint space angle (JSA) were compared in standing knee radiographs before and one year after OWHTO. The subluxation-C and subluxation-L were converted to a percentage of the tibial plateau width. RESULTS: The mean subluxation-C of 6.5% before OWHTO significantly increased to a mean subluxation-C of 7.3% one year after OWHTO. The mean subluxation-L of 6.3% and JSA of 4.5° before OWHTO significantly decreased to a subluxation-L of 1.8% and JSA of 3.3° one year after OWHTO. The change in subluxation-L correlated with the change in femorotibial angle and correction loss (r=0.634, P<0.001 and r=0.463, P<0.001, respectively). CONCLUSION: The proximal tibia shifted medially relative to the distal femur after OWHTO. This medial shift correlated with the correction loss. The coronal subluxation might be one cause of correction loss.