Department of Orthopedic Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China.
Arch Orthop Trauma Surg. 2022 Jun;142(6):937-946. doi: 10.1007/s00402-020-03717-8. Epub 2021 Jan 8.
Undercorrection is a common problem in opening wedge high tibial osteotomy (OWHTO). We investigated the compression effect of cortex screw on the osteotomy gap and its clinical significance.
A standard OWHTO using the TomoFix plate was conducted on 20 bone models in two groups to get a 10-mm medial osteotomy gap. A cortex screw was used temporarily in a neutral (at the center) and an eccentric position (near the inclined plane) of the dynamic hole in group 1 and group 2, respectively. The mean of undercorrection observed in the two groups was compared using an independent t test. Also, the effect of compression on the gap between the plate and medial tibial cortex, and the osteotomy gap was evaluated using a Sine rule. Besides, the mean undercorrection observed was assessed for clinical significance based on the effect on the weight-bearing axis (WBA) using a Cosine Rule.
The mean undercorrection was 1.3 ± 0.6 mm and 2.6 ± 0.6 mm in group 1 and group 2, respectively. A significantly greater undercorrection was observed in group 2 (p < 0.001). The correction loss in group 2 has resulted from combinations of the sliding effect of the dynamic hole and oblique compression effect over the gap between the plate and medial tibial cortex whereas in group 1 it has only resulted from the oblique compression effect. The observed undercorrection in group 2 has resulted in clinically significant WBA shift (10%) over the width of the tibial plateau.
In OWHTO, compression is important for the stability and healing of osteotomy, but it can also cause loss of correction. In patients requiring large correction, the surgeon should control the amount of compression required and consider making extra osteotomy gap to avoid undercorrection. Furthermore, the placement of cortex screws in neutral is essential to lower the risk of undercorrection.
在开放式楔形胫骨高位截骨术（OWHTO）中，矫正不足是一个常见问题。我们研究了皮质骨螺钉对截骨间隙的压缩效果及其临床意义。
在两组 20 个骨模型中，采用 TomoFix 板进行标准 OWHTO，使内侧截骨间隙达到 10mm。在组 1 和组 2 中，皮质骨螺钉分别临时置于动力孔的中性（中心）和偏心（斜面附近）位置。采用独立 t 检验比较两组的平均矫正不足。同时，采用正弦法则评估皮质骨螺钉对钢板与胫骨内侧皮质间隙及截骨间隙的压缩效果。此外，根据余弦法则，评估皮质骨螺钉对负重轴（WBA）的影响，确定平均矫正不足的临床意义。
组 1 和组 2 的平均矫正不足分别为 1.3±0.6mm 和 2.6±0.6mm。组 2 的矫正不足明显更大（p<0.001）。组 2 的矫正丢失是由动力孔的滑动效应和钢板与胫骨内侧皮质间隙的斜向压缩效应共同作用所致，而组 1 仅由斜向压缩效应引起。组 2 观察到的矫正不足导致了 WBA 在胫骨平台宽度上的临床显著变化（10%）。
在 OWHTO 中，压缩对于截骨的稳定性和愈合很重要，但也会导致矫正丢失。对于需要较大矫正的患者，术者应控制所需的压缩量，并考虑额外增加截骨间隙以避免矫正不足。此外，皮质骨螺钉中立位放置对于降低矫正不足的风险至关重要。
