Hau Raphael, Hammeschlag Joshua, Law Christopher, Wang Kemble K
Department of Orthopaedic Surgery, Box Hill Hospital, Eastern Health, 8 Arnold Street, Box Hill, Melbourne, VIC, 3128, Australia.
Department of Orthopaedic Surgery, Northern Health, Melbourne, 185 Cooper St, Epping, Melbourne, VIC, 3076, Australia.
J Orthop Surg Res. 2018 Nov 19;13(1):289. doi: 10.1186/s13018-018-1000-1.
Lipped or elevated acetabular liners are frequently used in total hip arthroplasty to improve stability. However, the optimal position of the lip is not known. The purpose of this study was to determine the optimal position of lipped acetabular liners in total hip arthroplasty performed with a posterior approach.
In 14 hips, lipped trial liners were placed intraoperatively in various positions around the posterior clock-face of the implanted acetabular shell component. For each liner position, stability of the hip was tested at maximal hip flexion with gradually increasing internal rotation until subluxation occurred, at which point the position of the hip was measured using smartphone accelerometer-based goniometers. Smartphone goniometers were first validated against a computer-assisted navigation system. Post-operative radiographs were analyzed for cup inclination angle, cup anteversion angle, and femoral offset.
Mean cup inclination angle in our series was 31° ± 6°. The most common liner position that imparted the greatest stability to posterior subluxation was posteriorly and inferiorly (4 o'clock position for left hip, or 8 o'clock position for right hip). The range for most stable liner position for different patients varied from postero-superior (11 o'clock/1 o'clock position) to directly inferior (6 o'clock position). Comparing a non-lipped liner to a lipped liner placed in the optimal position, the average difference in internal rotation gained before dislocation was 23°. There was no association between cup inclination or anteversion angle with liner position of greatest stability.
In hip replacements performed through a posterior approach and with mean cup inclination angle of 31° ± 6°, placing the lip of the elevated liner in the postero-inferior quadrant may impart more stability than in the postero-superior quadrant.
带唇缘或抬高的髋臼衬垫在全髋关节置换术中常用于提高稳定性。然而，唇缘的最佳位置尚不清楚。本研究的目的是确定在采用后入路进行的全髋关节置换术中带唇缘髋臼衬垫的最佳位置。
在14例髋关节中，术中将带唇缘的试验衬垫放置在植入髋臼杯组件后时钟面的不同位置。对于每个衬垫位置，在髋关节最大屈曲时测试髋关节的稳定性，并逐渐增加内旋直至半脱位发生，此时使用基于智能手机加速度计的测角仪测量髋关节的位置。智能手机测角仪首先与计算机辅助导航系统进行验证。对术后X线片进行分析，测量髋臼杯倾斜角、髋臼杯前倾角和股骨偏心距。
我们系列中的平均髋臼杯倾斜角为31°±6°。对后脱位稳定性影响最大的最常见衬垫位置是后下方（左髋为4点位置，右髋为8点位置）。不同患者最稳定衬垫位置的范围从后上方（11点/1点位置）到正下方（6点位置）不等。将无唇缘衬垫与放置在最佳位置的带唇缘衬垫进行比较，脱位前获得的内旋平均差异为23°。髋臼杯倾斜角或前倾角与最稳定衬垫位置之间无关联。
在采用后入路且平均髋臼杯倾斜角为31°±6°的髋关节置换术中，将抬高衬垫的唇缘放置在后下象限可能比后上象限更稳定。
