Department of Orthopedics and Traumatology, Turku University Hospital, Turku, Finland, Finnish Arthroplasty Register, Helsinki, Finland.
Swedish Hip Arthroplasty Register, Department of Orthopaedics, Institute of Surgical Sciences, Sahlgrenska University Hospital, Gothenburg, Sweden.
Acta Orthop. 2020 Dec;91(6):682-686. doi: 10.1080/17453674.2020.1788290. Epub 2020 Jul 3.
Background and purpose - The use of trabecular metal cups in primary total hip arthroplasty (THA) is increasing, despite the survival of Continuum cups being slightly inferior compared with other uncemented cups in registries. This difference is mainly explained by a higher rate of dislocation revisions. Cup malpositioning is a risk factor for dislocation and, being made of a highly porous material, Continuum cups might be more difficult to position. We evaluated whether Continuum cups had worse cup positioning compared with other uncemented cups. Patients and methods - Based on power calculation, 150 Continuum cups from 1 center were propensity score matched with 150 other uncemented cups from 4 centers. All patients had an uncemented stem, femoral head size of 32 mm or 36 mm, and BMI between 19 and 35. All operations were done for primary osteoarthrosis through a posterior approach. Patients were matched using age, sex, and BMI. Cup positioning was measured from anteroposterior pelvic radiograph using the Martell Hip Analysis Suite software. Results - There was no clinically relevant difference in mean inclination angle between the study group and the control group (43° [95% CI 41-44] and 43° [CI 42-45], respectively). The study group had a larger mean anteversion angle compared with the control group, 19° (CI 18-20) and 17° (CI 15-18) respectively. Interpretation - Continuum cups had a greater anteversion compared with the other uncemented cups. However, the median anteversion was acceptable in both groups and this difference does not explain the larger dislocation rate in the Continuum cups observed in earlier studies.
尽管连续杯在注册中心的存活率略低于其他非骨水泥杯，但在初次全髋关节置换术（THA）中使用小梁金属杯的情况正在增加。这种差异主要归因于更高的脱位翻修率。杯位不正会增加脱位的风险，而连续杯是由高多孔材料制成的，因此可能更难定位。我们评估了连续杯与其他非骨水泥杯相比是否存在更差的杯位。
基于功效计算，从 1 个中心的 150 个连续杯中，采用倾向性评分匹配法，与来自 4 个中心的 150 个其他非骨水泥杯进行匹配。所有患者均采用非骨水泥柄、32mm 或 36mm 股骨头大小和 19 至 35 之间的 BMI。所有手术均通过后入路进行，用于原发性骨关节炎。患者通过年龄、性别和 BMI 进行匹配。使用 Martell Hip Analysis Suite 软件从骨盆前后位 X 线片测量杯位。
研究组和对照组的平均倾斜角无明显差异（43°[95%CI 41-44]和 43°[CI 42-45]）。与对照组相比，研究组的平均前倾角较大，分别为 19°（CI 18-20）和 17°（CI 15-18）。
与其他非骨水泥杯相比，连续杯的前倾角更大。然而，两组的中位前倾角均在可接受范围内，这种差异并不能解释早期研究中观察到的连续杯更高的脱位率。
