2021 ISAKOS Biennial Congress ePoster
The incidence of violation of osteotomy plate by D-hole screw in medial open high tibial osteotomy and its risk factors
Jaehong Park, MD, Jongno-gu, Seoul KOREA, REPUBLIC OF
Chanhee Cho, MD KOREA, REPUBLIC OF
Myung Chul Lee, MD, PhD, Prof., Seoul KOREA, REPUBLIC OF
Hyuk-Soo Han, MD, PhD, Seoul KOREA, REPUBLIC OF
Duhyun Ro, MD, Prof. , Jongno-Gu, Seoul KOREA, REPUBLIC OF
Department of Orthopedic Surgery, Jongno-gu, Seoul, KOREA, REPUBLIC OF
FDA Status Cleared
Summary
The incidence of D-hole screw violation of osteotomy plane was 20.3% to 59.4% according to the location of the plate and plate location and height were important factors of D-hole screw violation.
ePosters will be available shortly before Congress
Abstract
Introduction
Because of relative larger size of TomoFix plate for Asian people, insertion of locking screw in D-hole of Tomofix plate would not be possible which might induce fixation failure or breakage of plate by stress loading on D-hole. The purposes of this study were to evaluate the incidence of violation of D-hole screw of osteotomy plane and to find the risk factors of it.
Methods
This study retrospectively reviewed computed tomography (CT) and X-rays of the 66 knees of 49 patients who underwent OW-HTO. Virtual osteotomy plane (VOP) was created using a multiplanar reconstruction of a CT scan. VOP started just from above the pes anserinus insertion of tibia and towards the proximal tibio-fibular junction. Then, length between the corner of medial tibial condyle and starting point of VOP was measured and defined proximal segment length (PSL). The tip of Tomofix plate® is set to be located 5,7 and 10 mm below the joint line. Then, 25mm was added which is the length from the tip of plate to lower margin of the D-hole (i.e. 30, 32, 35mm). If it is greater than PSL, it was considered as violation. Average height, tibia length, medial proximal tibial angle, and mechanical axis was compared between violated and non-violated groups.
Results
When tip of plate was located to 5,7 and 10 mm from the joint line, 20.3%, 32.8% and 59.4% of D-hole screw violated VOP, respectively Average height was smaller in violated groups regardless of location of plate (p < 0.001, p < 0.001, p < 0.001). When plate tip was located 7mm from the joint line, optimal cutoff value for the height to predict D-hole violation was 155.3cm(sensitivity, 90.7%, specificity, 81%).
Conclusion
The incidence of D-hole screw violation of osteotomy plane was 20.3% to 59.4% according to the location of the plate. Plate location and height were an important factor that predicts whether the D-hole screw of the tomofix plate violates the osteotomy site from OW-HTO when using tomofix plate. Therefore, with patients that has the height of 155.3 cm or less, a device smaller than the tomofix plate seems to be a more reasonable option, and violating the pes anserinus to lower the osteotomy site is also a consideration.