AZ St Maarten, Duffel, Belgium.
Zuyderland Medical Centre, Sittard-Geleen, The Netherlands.
Knee Surg Sports Traumatol Arthrosc. 2018 Jun;26(6):1823-1830. doi: 10.1007/s00167-017-4826-x. Epub 2017 Dec 27.
Patient-specific instrumentation (PSI) is a technique to plan and position the prosthesis components in unicompartmental knee arthroplasty (UKA) surgery. This study assesses whether the definitive component position in the frontal, sagittal and axial plane is according to the preoperative plan, based on the hypothesis that PSI is accurate.
Twenty-six patients who had PSI Oxford UKA surgery were included prospectively. The component position in vivo was determined with a postoperative CT-scan and compared with the planned component position using MRI-based digital 3D imaging. Adjustments to the preoperative plan and implanted component sizes during surgery were recorded.
Intraoperatively, no femoral adjustments were performed; 12 tibial re-resections were necessary. The median absolute deviation from the plan in degrees (range) in the frontal, sagittal and axial plane was 1.8° (- 1.5°-6.5°), 2.0° (- 6.5°-8.0°) and 1.0° (- 1.5°-5.0°) for the femoral component, and 2.5° (- 1.0°-6.0°), 3.0° (- 1.0°-5.0°) and 5.0° (- 6.5°-12.5°) for the tibial component. The femoral component is positioned 0.5 (- 1°-2.5°) mm more lateral and 0.8 (- 1.0°-2.5°) mm more anterior. The tibial component is positioned 2.0 (- 5.0-0.0) mm more lateral and 1.3 (- 3.0-6.0) mm more distal. The femoral and tibial default plans were changed four times (15.4%) and nine times (34.6%), respectively, before approval by the surgeon.
PSI in Oxford UKA surgery is reliable and accurately translates the preoperative plan into the in vivo situation, except for the tibial rotational position. The preoperative planning is a crucial step in avoiding re-resections that can cause angular deviations in prosthesis position, especially in tibial component rotational position. It is advised to avoid re-resections and to consider this while planning the PSI procedure.
Prospective comparative study Level II.
患者特定手术仪器（PSI）是一种用于规划和定位单髁膝关节置换术（UKA）中假体组件的技术。本研究评估了基于 PSI 准确的假设，在额状面、矢状面和轴面，最终组件位置是否符合术前计划。
前瞻性纳入 26 例接受 PSI Oxford UKA 手术的患者。通过术后 CT 扫描确定组件的体内位置，并使用基于 MRI 的数字 3D 成像与计划组件位置进行比较。记录术中对术前计划的调整和植入组件尺寸的调整。
术中未进行股骨调整；12 例胫骨需再次切除。股骨组件在额状面、矢状面和轴面的计划与实际差值中位数（范围）为 1.8°（-1.5°-6.5°）、2.0°（-6.5°-8.0°）和 1.0°（-1.5°-5.0°），胫骨组件分别为 2.5°（-1.0°-6.0°）、3.0°（-1.0°-5.0°）和 5.0°（-6.5°-12.5°）。股骨组件更偏向外侧 0.5 毫米（-1°-2.5°），更向前 0.8 毫米（-1.0°-2.5°）。胫骨组件更偏向外侧 2.0 毫米（-5.0-0.0），更向远侧 1.3 毫米（-3.0-6.0）。股骨和胫骨默认计划在获得外科医生批准前分别改变了 4 次（15.4%）和 9 次（34.6%）。
Oxford UKA 手术中的 PSI 是可靠的，能够准确地将术前计划转化为体内情况，除了胫骨旋转位置。术前规划是避免导致假体位置角度偏差的关键步骤，特别是在胫骨组件旋转位置。建议避免再次切除，并在规划 PSI 手术时考虑这一点。
前瞻性比较研究，二级。
