Department of Orthopedic Surgery and Traumatology, Freiburg University Medical Center, Hugstetter Str. 55, 79106 Freiburg, Germany.
Knee Surg Sports Traumatol Arthrosc. 2010 Oct;18(10):1317-22. doi: 10.1007/s00167-010-1144-y. Epub 2010 Apr 21.
Valid and reproducible measurements of limb alignment are prerequisites for planning, performing and evaluating TKAs. Although navigation systems have been shown to be reproducible tool for intraoperative TKA alignment measurements, particular doubt has been raised on the correlation with postoperative radiographic measurements. The aim of the present study was to evaluate whether the association of postoperative radiographic and navigation measurements of limb alignment was dependent on the time of acquisition. For this purpose, we retrospectively compared two groups of patients who underwent computer-assisted cemented TKA for osteoarthritis of the knee. Intraoperative navigation measurements (OrthoPilot™, Aesculap, Tuttlingen, Germany) were recorded before any cuts were made and again after implants had been placed. Long leg standing radiographs were acquired preoperatively in both the groups and either 2 weeks or 3 months postoperatively and AP limb alignment measurements were correlated with those of the respective navigation assessments. Preoperative deformity was similar in both the groups and correlation between radiographic and navigation measurements was excellent in both groups (ρ = 0.845 and 0.945, respectively). However, both mean and maximum discrepancies between radiographic and navigation measurements of leg alignment were significantly larger when radiographs were obtained 2 weeks (2.6° ± 2.1°, max. 10°) when compared with 3 months (1.8° ± 1.4°, max. 5°) postoperatively (P = 0.026). Accordingly, correlation between radiographic and navigation measurements was poor when radiographs were obtained 2 weeks postoperatively (ρ = 0.26, n.s.) but in the range of preoperative assessments when obtained 3 months postoperatively (ρ = 0.841, P < 0.001). Radiographic and navigation measurements of TKA limb alignment correlate well preoperatively. Equally good correlations can only be achieved when postoperative radiographic measurements are delayed to a time when more patients achieve full or near-full extension and are able to bear full weight leading to more valid radiographs.
肢体对线的准确且可重现的测量是规划、执行和评估 TKA 的前提条件。虽然导航系统已被证明是用于术中 TKA 对线测量的可重现工具，但人们对其与术后放射学测量的相关性特别提出了质疑。本研究的目的是评估术后放射学和导航对线测量的相关性是否取决于采集时间。为此，我们回顾性比较了两组接受计算机辅助骨水泥 TKA 治疗膝关节骨关节炎的患者。在进行任何截骨前和植入物放置后，记录术中导航测量值（OrthoPilot™，Aesculap，Tuttlingen，德国）。两组患者术前均拍摄长腿站立位 X 线片，术后 2 周或 3 个月拍摄 X 线片，并将其与各自的导航评估进行相关性分析。两组患者的术前畸形相似，且两组的放射学和导航测量值相关性均良好（ρ=0.845 和 0.945）。然而，当术后 2 周（2.6°±2.1°，最大 10°）获得 X 线片时，下肢对线的放射学和导航测量值的平均和最大差异均明显大于术后 3 个月（1.8°±1.4°，最大 5°）（P=0.026）。因此，当术后 2 周获得 X 线片时，放射学和导航测量值之间的相关性较差（ρ=0.26，n.s.），但当术后 3 个月获得 X 线片时，其相关性与术前评估相似（ρ=0.841，P<0.001）。TKA 下肢对线的放射学和导航测量值在术前相关性良好。只有当术后放射学测量值延迟到更多患者实现完全或接近完全伸展并能够承受全重的时间时，才能获得同样良好的相关性，从而获得更准确的 X 线片。
