Musculoskeletal Research Unit, CQ University, Yaamba Road, Rockhampton 4700, Australia.
J Orthop Surg Res. 2011 Aug 10;6:40. doi: 10.1186/1749-799X-6-40.
Correct placement of the acetabular cup is a crucial step in total hip replacement to achieve a satisfactory result and remains a challenge with free-hand techniques. Imageless navigation may provide a viable alternative to free-hand technique and improve placement significantly. The purpose of this project was to assess and validate intra-operative placement values for both inclination and anteversion as displayed by an imageless navigation system to post-operative measurement of cup position using high resolution CT scans.
Thirty-two subjects who underwent primary hip joint arthroplasty using imageless navigation were included. The average age was 66.5 years (range 32-87). 23 non-cemented and 9 cemented acetabular cups were implanted. The desired position for the cup was 45 degrees of inversion and 15 degrees of anteversion. A pelvic CT scan using a multi-slice CT was used to assess the position of the cup radiographically.
Two subjects were excluded because of dislodgement of the tracking pin. Pearson correlation revealed a strong and significant correlation (r = 0.68; p < 0.006) for cup inclination and a moderate non-significant correlation (r = 0.53; p = 0.45) between intra-operative readings and cup placement for anteversion.
These findings can be explained with the possible introduction of systematic error. Even though the acquisition of anatomic landmarks is simple, they must be acquired with great precision. An error of 1 cm can result in a mean anteversion error of 6 degrees and inclination error of 2.5 degrees. Whilst computer assisted surgery results in highly accurate cup placements for inclination, anteversion of the cup cannot be determined accurately.
在全髋关节置换术中，髋臼杯的正确放置是达到满意效果的关键步骤，而徒手技术仍然具有挑战性。无影像导航技术可能是徒手技术的可行替代方法，可以显著改善髋臼杯的位置。本项目旨在评估和验证无影像导航系统术中显示的髋臼杯倾斜度和前倾角的放置值，并与高分辨率 CT 扫描术后测量的髋臼杯位置进行比较。
共纳入 32 例接受无影像导航初次髋关节置换术的患者。平均年龄为 66.5 岁（范围 32-87 岁）。23 例为非骨水泥髋臼杯，9 例为骨水泥髋臼杯。髋臼杯的理想位置为 45 度外翻和 15 度前倾角。使用多层 CT 进行骨盆 CT 扫描，以放射学方式评估髋臼杯的位置。
由于跟踪销脱落，有 2 例患者被排除在外。Pearson 相关分析显示，髋臼杯倾斜度的相关性很强且显著（r = 0.68；p < 0.006），而髋臼杯前倾角的术中读数与髋臼杯放置的相关性较弱但不显著（r = 0.53；p = 0.45）。
这些发现可以用可能引入的系统误差来解释。尽管获取解剖学标志很简单，但必须非常精确地获取。1 厘米的误差可能导致前倾角的平均误差为 6 度，倾斜度的平均误差为 2.5 度。虽然计算机辅助手术可以使髋臼杯的倾斜度放置非常精确，但髋臼杯的前倾角不能准确确定。
