Keehan Robert, Gill Amarit, Smith Lindsay, Ahmad Riaz, Eldridge Jonathan
Department of Trauma and Orthopaedics, Weston General Hospital, Grange Road, Weston super Mare, BS23 4TQ, UK.
Department of Trauma and Orthopaedics, Weston General Hospital, Grange Road, Weston super Mare, BS23 4TQ, UK; Bristol Medical School, University of Bristol, Beacon House, Queens Road, Bristol BS8 1QU, UK.
Knee. 2019 Dec;26(6):1204-1209. doi: 10.1016/j.knee.2019.10.011. Epub 2019 Nov 5.
Tibial tuberosity trochlear groove distance (TT-TG) is an important radiological measurement in patellofemoral instability (PFI). Where instability is recurrent, a value ≥20 mm is considered an indication for tubercle medialisation. Trochlear dysplasia commonly accompanies PFI. It can make identification of the deepest part of the trochlea difficult, which makes the TT-TG difficult or impossible to assess. To address this, we propose a new method of identifying the deepest part of trochlea based on the femoral epicondyles. It is named the tibial tuberosity mid inter-epicondyle trochlea intersection distance (TT-MIELTI).
The TT-TG and TT-MIELTI of 30 consecutive non-dysplastic knee MRIs were compared, excluding 96 knees with dysplasia, sulcus angles ≥135°, a tibial tuberosity anterior cortex which was not fully demonstrated, artefact, fracture, or Osgood Schlatter's disease. To assess inter-observer reliability three blinded researchers measured the TT-TG and the TT-MIELTI of all 30 knees. To assess intra-observer repeatability one researcher repeated the measurements after six weeks.
The intraclass correlation coefficient (ICC) test demonstrated good to excellent values for all measurements (TT-TG and TT-MIELTI correlation ICC 0.94-0.97; TT-TG inter-observer reliability ICC = 0.85, intra-observer repeatability ICC = 0.90; TT-MIELTI inter-observer reliability ICC = 0.86, intra-observer repeatability ICC = 0.89. All p values < .001.) CONCLUSIONS: In non-dysplastic knees the mid inter-epicondyle trochlea intersection (MIELTI) accurately identifies the deepest part of the trochlea, and TT-MIELTI is a reliable alternative to the TT-TG. Re-assessment in dysplastic knees would be of benefit to establish its usefulness in the clinical setting.
胫骨结节-滑车沟距离（TT-TG）是髌股关节不稳（PFI）的一项重要影像学测量指标。对于复发性不稳，TT-TG值≥20mm被视为结节内移的指征。滑车发育不良常伴随PFI。这会使滑车最深部的识别变得困难，进而导致TT-TG难以评估或无法评估。为解决这一问题，我们提出一种基于股骨髁识别滑车最深部的新方法。它被命名为胫骨结节-髁间中点-滑车交点距离（TT-MIELTI）。
比较了连续30例非发育不良膝关节MRI的TT-TG和TT-MIELTI，排除96例有发育不良、沟角≥135°、胫骨结节前皮质未充分显示、伪影、骨折或骨软骨炎的膝关节。为评估观察者间的可靠性，三名不知情的研究人员测量了所有30例膝关节的TT-TG和TT-MIELTI。为评估观察者内的可重复性，一名研究人员在六周后重复测量。
组内相关系数（ICC）测试显示所有测量值的相关性良好至优秀（TT-TG和TT-MIELTI相关性ICC为0.94 - 0.97；TT-TG观察者间可靠性ICC = 0.85，观察者内可重复性ICC = 0.90；TT-MIELTI观察者间可靠性ICC = 0.86，观察者内可重复性ICC = 0.89。所有p值均<0.001。）结论：在非发育不良的膝关节中，髁间中点-滑车交点（MIELTI）能准确识别滑车最深部，且TT-MIELTI是TT-TG的可靠替代指标。对发育不良的膝关节进行重新评估将有助于确定其在临床环境中的实用性。
