Worden Alicia, Kaar Scott, Owen Joshua, Cutuk Adnan
Department of Orthopaedic Surgery, Saint Louis University, Saint Louis, Missouri.
J Knee Surg. 2016 Oct;29(7):589-593. doi: 10.1055/s-0035-1569478. Epub 2015 Dec 30.
A lateralized tibial tubercle is an important anatomic predictor of patellar instability and can be used as an indication for a distal realignment procedure. Currently, tibial tubercle to trochlear groove (TT-TG) distance is measured on computed tomography (CT); however, radiographs could be a safer and more efficient modality. The aim of this study is to evaluate and compare TT-TG measurements obtained using CT, anatomical dissections, and a novel radiographic technique. Furthermore, we evaluated the effects of knee flexion and tibial rotation on these measurements. TT-TG distances were measured on 11 fresh cadaver specimens with CT and compared with anatomic measurements obtained from dissection in full knee extension and 90-degree flexion. Both imaging- and dissection-derived measurements were obtained in neutral, external, and internal tibial rotation. The TT-TG distance was also measured on a modified sunrise X-ray view (knee at 90 degrees). The TT-TG distance obtained on CT was 13.00 ± 1.05 mm and was comparable to measurements derived from anatomic dissections in extension (14.88 ± 1.10 mm) and 90 degrees (12.40 ± 1.93 mm) ( ≥ 0.05). The X-ray measurements of TT-TG distance (5.62 ± 1.16 mm) were significantly different than those measured on CT ( ≤ 0.05). TT-TG distances in neutral tibial position measured on CT and dissection were significantly different than distances measured in full external (19.79 ± 1.33 and 20.92 ± 1.15 mm, respectively) and internal tibia rotation (6.45 ± 1.00 and 10.33 ± 1.19 mm, respectively) ( ≤ 0.05). TT-TG distance measured on CT is comparable to measurements from dissections in both full extension and 90-degree flexion. Tibial rotation has a significant effect on TT-TG measurements. Radiographic measurements did not correlate with CT and anatomic measurements. CT-derived TT-TG measurements are accurate throughout knee range of motion; however, it is important to maintain neutral lower leg rotation to not generate a false-positive or false-negative measurement. Radiographic measurement of TT-TG ration is not currently recommended.
胫骨结节偏侧化是髌股关节不稳定的重要解剖学预测指标，可作为远端重新排列手术的指征。目前，胫骨结节至滑车沟（TT-TG）距离是在计算机断层扫描（CT）上测量的；然而，X线片可能是一种更安全、更有效的检查方式。本研究的目的是评估和比较使用CT、解剖学方法和一种新型X线技术测量的TT-TG距离。此外，我们还评估了膝关节屈曲和胫骨旋转对这些测量结果的影响。在11个新鲜尸体标本上用CT测量TT-TG距离，并与在膝关节完全伸直和90度屈曲时解剖测量得到的结果进行比较。在胫骨中立位、外旋和内旋时分别进行影像学测量和解剖测量。还在改良的日出位X线片（膝关节90度）上测量TT-TG距离。CT测量得到的TT-TG距离为13.00±1.05mm，与伸直位（14.88±1.10mm）和90度屈曲位（12.40±1.93mm）解剖测量得到的结果相当（P≥0.05）。X线片测量的TT-TG距离（5.62±1.16mm）与CT测量结果有显著差异（P≤0.05）。CT和解剖测量在胫骨中立位时的TT-TG距离与完全外旋（分别为19.79±1.33mm和20.92±1.15mm）和内旋（分别为6.45±1.00mm和10.33±1.19mm）时测量的距离有显著差异（P≤0.05）。CT测量的TT-TG距离与伸直位和90度屈曲位解剖测量的结果相当。胫骨旋转对TT-TG测量有显著影响。X线片测量结果与CT及解剖测量结果不相关。CT测量的TT-TG距离在膝关节活动范围内是准确的；然而，保持小腿中立旋转很重要，以免产生假阳性或假阴性测量结果。目前不推荐用X线片测量TT-TG比值。
