Purpose

To evaluate the incidence and morphology of medial cortical hinge fractures in lateral open wedge distal femoral osteotomy (LOW-DFO) and to determine a safe zone for the position of the osteotomy hinge to minimize the risk of hinge fractures.

Methods

Consecutive patients who underwent LOW-DFO for symptomatic valgus malalignment were screened for eligibility for this retrospective observational cohort study. Demographical and surgical data were collected. The incidence and morphology of medial cortical hinge fractures were evaluated on standard postoperative anterior–posterior knee radiographs. Comprehensive measurements evaluating the osteotomy gap and the position of the osteotomy hinge were taken. Additionally, each osteotomy hinge was assigned to a corresponding sector of a proposed five-sector grid of the distal medial femur.

Results

A total of 100 patients (60% female) with a mean age of 31 ± 13 years were included. The overall incidence of medial cortical hinge fractures was 46% and three distinct fracture types were identified. The most frequently observed fracture type was extension of the osteotomy gap (76%), followed by a proximal (20%) and distal (4%) course of the fracture line in relation to the hinge. Group comparison (hinge fracture vs. no hinge fracture) showed statistically significant higher values for the height of the osteotomy gap (p = 0.001), the wedge angle (p = 0.036), and the vertical distance between the hinge and the proximal margin of the adductor tubercle (AT; p = 0.002) in the hinge fracture group. Furthermore, a significantly lower horizontal distance between the hinge and the medial cortical bone (p = 0.036) was observed in the hinge fracture group. A statistically significant higher incidence of medial cortical hinge fractures was observed when the position of the osteotomy hinge was proximal compared to distal to the proximal margin of the AT (53% vs. 27%; p = 0.023).

Conclusion

Medial cortical hinge fractures in LOW-DFO are a common finding with three distinct fracture types. To minimize the risk of medial cortical hinge fractures, it is recommended to aim for a position of the osteotomy hinge at the level of or distal to the proximal margin of the adductor tubercle.

Level of evidence

Prognostic study; Level III

中文翻译：

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内收肌结节远端的铰链位置可最大限度地降低外侧开放楔形股骨远端截骨术中铰链骨折的风险。

目的

评估外侧开放楔形股骨远端截骨术（LOW-DFO）中内侧皮质铰链骨折的发生率和形态，并确定截骨铰链位置的安全区，以尽量减少铰链骨折的风险。

方法

对因症状性外翻畸形而接受 LOW-DFO 的连续患者进行了筛选，以符合这项回顾性观察性队列研究的资格。收集人口统计学和手术数据。在标准的术后膝关节前后位 X 光片上评估内侧皮质铰链骨折的发生率和形态。进行了评估截骨间隙和截骨铰链位置的综合测量。此外，每个截骨铰链都被分配到股骨远端内侧五扇区网格的相应扇区。

结果

共纳入 100 名患者（60% 为女性），平均年龄为 31 ± 13 岁。内侧皮质铰链骨折的总发生率为 46%，并确定了三种不同的骨折类型。最常见的骨折类型是截骨间隙的延伸（76%），其次是与铰链相关的骨折线的近端（20%）和远端（4%）过程。组比较（铰链骨折与无铰链骨折）显示截骨间隙高度（p  = 0.001）、楔角（p  = 0.036）以及铰链和近端边缘之间的垂直距离具有统计学意义的更高值。内收肌结节 (AT; p = 0.002）在铰链骨折组。 此外，在铰链骨折组中观察到铰链和内侧皮质骨之间的水平距离显着降低（p = 0.036）。当截骨铰链的位置在 AT 近端边缘的近端与远端相比时，观察到内侧皮质铰链骨折的发生率具有统计学意义（53% 对 27%；p  = 0.023）。

结论

LOW-DFO 中的内侧皮质铰链骨折是一种常见的发现，具有三种不同的骨折类型。为了最大限度地降低内侧皮质铰链骨折的风险，建议将截骨铰链的位置瞄准内收肌结节近端边缘的水平或远端。

证据级别

预后研究；三级