Department of Orthopedic Surgery and Joint Reconstructive Surgery, Toyama Municipal Hospital, 2-1 Imaizumi Hokubu-machi, Toyama, 939-8511, Japan.
Knee Surg Sports Traumatol Arthrosc. 2020 Jun;28(6):1827-1834. doi: 10.1007/s00167-019-05615-y. Epub 2019 Jul 4.
The study aimed to evaluate the optimal timing for plate removal after open-wedge high tibial osteotomy (OWHTO) without loss of correction and to investigate risk factors for loss of correction after plate removal. The study presents the hypothesis that plate removal without loss of correction was possible when gap filling reached zone 2 (25-50%) on anteroposterior radiographs.
Ninety-one patients (101 knees) who underwent OWHTO using the TomoFix plate were enrolled. Plate removal was performed at an average 16.4 ± 5.4 months after OWHTO. Clinical evaluation included plate-related symptoms, the Japanese Orthopedic Association Knee Score (JOA score), and Oxford Knee Score (OKS). Radiological outcomes, including the hip-knee-ankle angle (HKA), weight-bearing line ratio (WBLR), medial proximal tibial angle (MPTA), and posterior tibial slope (PTS), were evaluated preoperatively, at plate removal and at 1 year after plate removal. Computed tomography (CT) was performed at plate removal to evaluate the flange bone union, progression rates of gap filling, and posterior cortex bone union. In addition, the risk factors for loss of correction after plate removal were evaluated.
At plate removal, 63 (62.4%) knees had plate-related symptoms (mild, 56 knees; moderate, 7 knees; severe, 0). After plate removal, the JOA score did not change, whereas OKS further improved; six knees developed loss of correction. On CT evaluation at plate removal, the flange bone union was achieved in all cases; the progression rates of gap filling and posterior cortex bone union were 47.0% ± 16.6% and 62.8% ± 16.5%, respectively. A posterior cortex union rate of < 43.3% was the only predictor for loss of correction after plate removal (odds ratio: 1.38, P < 0.01).
Plate removal without loss of correction after OWHTO was possible when bone union of the posterior cortex reached the center of the osteotomy gap even in incompletely filled gaps.
Therapeutic case series, Level IV.
本研究旨在评估在不丢失矫正的情况下，开放式楔形胫骨高位截骨术（OWHTO）后钢板取出的最佳时机，并探讨钢板取出后丢失矫正的风险因素。本研究提出了一个假设，即当前后位 X 线片上的间隙填充达到 2 区（25%-50%）时，钢板取出后不丢失矫正。
共纳入 91 例（101 膝）接受 TomoFix 钢板治疗的 OWHTO 患者。OWHTO 后平均 16.4±5.4 个月行钢板取出术。临床评估包括与钢板相关的症状、日本矫形协会膝关节评分（JOA 评分）和牛津膝关节评分（OKS）。术前、钢板取出时及钢板取出后 1 年，评估放射学结果，包括髋膝踝角（HKA）、负重线比（WBLR）、胫骨近端内侧角（MPTA）和胫骨后倾角（PTS）。钢板取出时行 CT 检查，评估翼缘骨愈合、间隙填充进展率和后皮质骨愈合。此外，还评估了钢板取出后丢失矫正的风险因素。
钢板取出时，63 例（62.4%）膝关节有与钢板相关的症状（轻度 56 例，中度 7 例，重度 0 例）。钢板取出后，JOA 评分无变化，而 OKS 进一步改善，6 例出现矫正丢失。在 CT 评估中，所有病例均达到翼缘骨愈合；间隙填充和后皮质骨愈合的进展率分别为 47.0%±16.6%和 62.8%±16.5%。钢板取出后皮质骨未愈合率<43.3%是丢失矫正的唯一预测因素（比值比：1.38，P<0.01）。
OWHTO 后，当后皮质骨愈合到达截骨间隙中心时，即使间隙未完全填充，也可安全取出钢板而不丢失矫正。
治疗性病例系列，IV 级。
