Proximal anatomical axes show bidirectional variability: Accurate tibial slope requires mechanical axis measurement

IF 5.5 2区医学 Q1 ORTHOPEDICS

Knee Surgery, Sports Traumatology, Arthroscopy Pub Date : 2026-09-29 Epub Date: 2025-10-22 DOI:10.1002/ksa.70093

Barbara C. Boer, Quinten W. T. Veerman, Reinoud W. Brouwer, Judith olde Heuvel, Tony G. van Tienen, Wolf Petersen, Roy A. G. Hoogeslag

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引用次数: 0

Abstract

Purpose

To determine whether posterior tibial slope (PTS) measured to proximal anatomical axes can serve as a reliable proxy for PTS measured to the mechanical tibial axis (mTA).

Methods

In patients ≥18 years with failed anterior cruciate ligament reconstruction, medial and lateral PTS were measured relative to the mTA on a lateral lower-leg radiograph, and relative to the proximal tibial anatomical axis (PTAA), anterior tibial cortical axis (ATC) and posterior tibial cortical axis (PTC) on a lateral knee radiograph. Agreement was assessed using correlation coefficients, measurement error and Bland–Altman analysis. Diagnostic accuracy of the conventional ≥12° PTAA-based PTS cut-off for slope-reducing osteotomy was determined.

Results

Fifty-nine knees were analyzed. Correlation between proximal anatomical axes and mTA-based PTS measurements was strong (r ≥ 0.71), but agreement was poor. Mean measurement error for PTAA was 0.1 ± 2.4° (range: −5.7° to 7.6°) and −0.5 ± 2.4° (range: −6.6° to 5.2°), for ATC −3.4 ± 2.6° (range: −8.6° to 5.9°) and −3.7 ± 2.6° (range: −9.9° to 2.7°) and for PTC 3.0 ± 2.6° (range: −2.9° to 10.4°) and 2.7 ± 2.4° (range: −3.6° to 7.8°) for the medial and lateral plateau, respectively. For PTAA, absolute measurement error ≥2° occurred in approximately 50% of knees. Bland–Altman analysis showed 95% levels of agreement ranging from −4.89° to 4.62° (medial) and −5.11° to 4.11° (lateral). Using the ≥12° cut-off on PTAA-based PTS values misclassified approximately one in three knees (19.5% false-positive and 13.2% false-negative) relative to the mTA-based PTS reference values.

Conclusion

Despite strong correlation, proximal anatomical axes-based PTS measurements on routine lateral knee radiographs show substantial, bidirectional measurement error outside clinically acceptable limits of agreement compared to mTA-based PTS measurements on full-length lateral lower-leg radiographs. Single-exposure, full-length lateral lower-leg radiographs should be obtained to measure PTS relative to the mTA when considering slope-reducing osteotomy.

Level of Evidence

Level IV.

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近端解剖轴显示双向变异性：准确的胫骨斜率需要机械轴测量。

目的：确定胫骨后斜率（PTS）测量到近端解剖轴是否可以作为可靠的替代PTS测量到机械胫骨轴（mTA）。方法：在18岁以上前交叉韧带重建失败的患者中，测量内侧和外侧PTS相对于下肢外侧x线片上的mTA，以及相对于膝关节外侧x线片上的胫骨近端解剖轴（PTAA）、胫骨前皮质轴（ATC）和胫骨后皮质轴（PTC）。使用相关系数、测量误差和Bland-Altman分析评估一致性。确定常规≥12°pta为基础的PTS截骨斜率降低的诊断准确性。结果：对59例膝关节进行了分析。近端解剖轴与基于mta的PTS测量结果相关性很强（r≥0.71），但一致性较差。PTAA的平均测量误差分别为0.1±2.4°（范围：-5.7°至7.6°）和-0.5±2.4°（范围：-6.6°至5.2°），ATC的平均测量误差为-3.4±2.6°（范围：-8.6°至5.9°）和-3.7±2.6°（范围：-9.9°至2.7°），PTC的平均测量误差分别为3.0±2.6°（范围：-2.9°至10.4°）和2.7±2.4°（范围：-3.6°至7.8°）。对于PTAA，大约50%的膝关节发生绝对测量误差≥2°。Bland-Altman分析显示95%的一致性水平范围为-4.89°至4.62°（内侧）和-5.11°至4.11°（外侧）。相对于基于mta的PTS参考值，使用≥12°截断值对基于pta的PTS值进行误分类约三分之一（19.5%假阳性和13.2%假阴性）。结论：尽管有很强的相关性，常规膝侧位x线片上基于近端解剖轴的PTS测量与基于mta的全长下肢侧位x线片上的PTS测量相比，显示出明显的、超出临床可接受范围的双向测量误差。当考虑减坡截骨时，应获得单次曝光、全长侧位下肢x线片，以测量相对于mTA的PTS。证据等级：四级。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Knee Surgery, Sports Traumatology, Arthroscopy 医学-外科

CiteScore

8.10

自引率

18.40%

发文量

418

审稿时长

2 months

期刊介绍： Few other areas of orthopedic surgery and traumatology have undergone such a dramatic evolution in the last 10 years as knee surgery, arthroscopy and sports traumatology. Ranked among the top 33% of journals in both Orthopedics and Sports Sciences, the goal of this European journal is to publish papers about innovative knee surgery, sports trauma surgery and arthroscopy. Each issue features a series of peer-reviewed articles that deal with diagnosis and management and with basic research. Each issue also contains at least one review article about an important clinical problem. Case presentations or short notes about technical innovations are also accepted for publication. The articles cover all aspects of knee surgery and all types of sports trauma; in addition, epidemiology, diagnosis, treatment and prevention, and all types of arthroscopy (not only the knee but also the shoulder, elbow, wrist, hip, ankle, etc.) are addressed. Articles on new diagnostic techniques such as MRI and ultrasound and high-quality articles about the biomechanics of joints, muscles and tendons are included. Although this is largely a clinical journal, it is also open to basic research with clinical relevance. Because the journal is supported by a distinguished European Editorial Board, assisted by an international Advisory Board, you can be assured that the journal maintains the highest standards. Official Clinical Journal of the European Society of Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA).