Hingelbaum Swen, Best Raymond, Huth Jochen, Wagner Daniel, Bauer Gerhard, Mauch Frieder
Sportklinik Stuttgart, Taubenheimstr. 8, 70372, Stuttgart, Germany.
Knee Surg Sports Traumatol Arthrosc. 2014 Oct;22(10):2388-95. doi: 10.1007/s00167-014-3204-1. Epub 2014 Aug 2.
Medial transfer of the tibial tubercle has become a standard procedure in cases of patella instability caused by an increased tuberositas tibae-trochlear groove (TT-TG) distance. However, the TT-TG distance has always been assessed as an absolute value without taking individual joint size into consideration. It was assumed that the pathological influence of the TT-TG distance correlates with individual joint size. Aim of the current study therefore was to develop a method to express TT-TG distance in relation to these joint variables.
Two hundred knee MRI scans of healthy individuals (69 females and 131 males) were evaluated retrospectively in a control group. First, the TT-TG distance was measured as described by Schoettle et al. To determine joint size, the proximal-distal distance between the entrance of the chondral trochlear groove (TE) and the onset of the patella tendon at the tibial tubercle (TT) was selected. Subsequently, the TT-TG/TT-TE ratio expresses the relationship between the TT-TG distance and the proximal-distal distance from the entrance of the chondral trochlear groove to the height of the tibial tubercle. The TT-TG Index can also be expressed as an angle (TT-TG angle). Likewise, in another patient group, 54 knee MRTs of patients with patellofemoral instability were evaluated.
The average TT-TG distance of the control group was 7.5±3.5 mm (range 0-17.4 mm) with no significant differences between genders. The mean TT-TE distance was 63.9 mm (range 49-79 mm) with there being significant differences between genders. The resulting mean TT-TG Index was 0.12±0.05 (range 0-0.25). In the patient group, the average TT-TG distance was 13.5±4.1 mm and the average TT-TE distance was 61.3±6.8 mm. The resulting average TT-TG Index of 0.22±0.07 in the patient group (PFI) approximates the threshold determined by the 95% confidence interval in the healthy control group. A direct comparison between the control group and the patient group revealed a significant difference in the TT-TG distance (p=0.0001), in the TT-TE distance (p<0.0042) and in the resulting TT-TG Index (p<0.0001).
The measurement of the TT-TG Index is a reliable and differentiated approach for determining the lateral displacement of the tibial tubercle in relation to the proximal trochlear groove. The pathological influence of the TT-TG distance in case of patella instability depends on individual joint size, confirming the initial hypothesis. We currently consider a TT-TG Index>0.23 to be pathological based on our findings. Particularly, in case of a marginal TT-TG distance, the additional relative TT-TG Index facilitates a decision concerning an indication for a operative medial transfer of the tibial tubercle.
II.
在胫骨结节 - 滑车沟（TT - TG）距离增加导致髌骨不稳定的病例中，胫骨结节内移已成为一种标准手术。然而，TT - TG距离一直被评估为一个绝对值，而未考虑个体关节大小。据推测，TT - TG距离的病理影响与个体关节大小相关。因此，本研究的目的是开发一种方法来表达与这些关节变量相关的TT - TG距离。
在一个对照组中，对200例健康个体（69名女性和131名男性）的膝关节MRI扫描进行回顾性评估。首先，按照Schoettle等人描述的方法测量TT - TG距离。为确定关节大小，选择软骨滑车沟入口（TE）与胫骨结节处髌腱起点之间的近端 - 远端距离。随后，TT - TG/TT - TE比值表达了TT - TG距离与从软骨滑车沟入口到胫骨结节高度的近端 - 远端距离之间的关系。TT - TG指数也可以表示为一个角度（TT - TG角）。同样，在另一组患者中，对54例髌股关节不稳定患者的膝关节MRT进行了评估。
对照组的平均TT - TG距离为7.5±3.5mm（范围0 - 17.4mm），性别之间无显著差异。平均TT - TE距离为63.9mm（范围49 - 79mm），性别之间存在显著差异。得出的平均TT - TG指数为0.12±0.05（范围0 - 0.25）。在患者组中，平均TT - TG距离为13.5±4.1mm，平均TT - TE距离为61.3±6.8mm。患者组（髌股关节不稳定，PFI）得出的平均TT - TG指数为0.22±0.07，接近健康对照组95%置信区间确定的阈值。对照组与患者组之间的直接比较显示，TT - TG距离（p = 0.0001）、TT - TE距离（p < 0.0042）以及得出的TT - TG指数（p < 0.0001）存在显著差异。
测量TT - TG指数是一种可靠且有差异的方法，用于确定胫骨结节相对于近端滑车沟的外侧移位。在髌骨不稳定情况下，TT - TG距离的病理影响取决于个体关节大小，证实了最初的假设。基于我们的研究结果，我们目前认为TT - TG指数>0.23为病理性。特别是，在TT - TG距离处于临界值的情况下，额外的相对TT - TG指数有助于决定是否对胫骨结节进行手术内移。
II级
