2023 ISAKOS Biennial Congress ePoster
Calipered Measurements Method For Kinematically Aligned Total Knee Arthroplasty Has A Risk Of Excessive Varus Cut For The Proximal Tibia In Japanese Varus Knees
Umito Kuwashima, MD, PhD, Tokyo JAPAN
Masafumi Itoh, MD, PhD, Tokyo JAPAN
Junya Itou, MD, Tokyo JAPAN
Ken Okazaki, MD, PhD, Tokyo JAPAN
Tokyo Women's Medical University, Tokyo, JAPAN
FDA Status Not Applicable
Summary
Excessive joint line obliquity can occur when calipered KA TKA is performed in Japanese patients with varus OA knees, and surgeons should consider employing modifications when determining the coronal alignment of the proximal tibial cut for calipered KA TKA in these patients.
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Abstract
Background
Calipered kinematically aligned total knee arthroplasty (KA TKA) has been reported to provide promising clinical results and higher long-term survival rates. The tibia is prone to excessive varus deformity in the Japanese population, which can cause excessive joint line obliquity after calipered KA TKA. The purpose of this study was to elucidate the joint line angle on the distal femur and proximal tibia in patients undergoing TKA in Japan and to determine the risk of significant obliquity of the osteotomy surface using the calipered KA TKA method.
Methods
Forty-four patients (50 consecutive knees) with osteoarthritis (OA) awaiting TKA were chosen as study participants. We simulated the calipered KA TKA measurements based on preoperative computed tomography (CT) images using planning software (ZedKnee; LEXI, Tokyo, Japan). Surgical simulation was performed using LEGION CR. After considering the 9-mm thickness of the implants and 2-mm thickness of the cartilage, the distal and posterior femur and proximal tibia were resected at 7 mm. We investigated the lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), and hip-knee-ankle angle (HKA) from the simulated calipered KA TKA measurements.
Results
The mean MPTA was -5.9° ± 2.5° (-11.8° to -0.5°), and 68% of patients showed a MPTA of < -5°. The mean LDFA was 2.4° ± 3.1° (-6.6° to 10.3°), and 20% of patients showed an LDFA of > 5°. The mean HKA was -3.6° ± 3.6° (-10.6° to 2.8°), with 38% of patients showing a HKA of < -5°.
Conclusions
Excessive joint line obliquity can occur when calipered KA TKA is performed in Japanese patients with varus OA knees. Surgeons should consider modifications when determining the coronal alignment of the proximal tibial cut for calipered KA TKA in these patients.