PURPOSE Patellofemoral instability can be caused by tibial or femoral torsional deformity. Established surgical treatment options are rotational osteotomies, but the transfer from pre-operative planning to surgical execution can be challenging. Patient-specific instruments (PSI) are proofed to be helpful tools in realignment surgery. However, accuracy of PSI in femoral and tibial rotational osteotomies remains still unknown. Goal of the present study was to evaluate the accuracy of PSI in femoral and tibial rotational osteotomies in a patient population suffering from patellofemoral instability. METHODS All patients that underwent femoral or tibial rotational osteotomy using PSI in case of patellofemoral instability from October 2015 until April 2019 in our clinic were included. Twelve knees with twelve supracondylar femoral and seven supratuberositary tibial rotational osteotomies could be included. Accuracy of the correction was assessed using pre- and post-operative CT scans based on conventional measurements and, in 3D, based on 3D bone models of the respective patients. RESULTS CT measurements revealed an absolute difference between planned and achieved rotation of 4.8° ± 3.1° for femoral and 7.9° ± 3.7° for tibial rotational osteotomies without significant difference (p = 0.069). Regarding 3D assessment, a significant difference could be observed for the residual error between femoral and tibial rotational osteotomies in the 3D angle (p = 0.014) with a higher accuracy for the femoral side. CONCLUSION The application of PSI for femoral and tibial rotational osteotomy is a safe surgical treatment option. Accuracy for femoral rotational osteotomies is higher compared with tibial rotational osteotomies using PSI.

中文翻译：

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股骨和胫骨旋转截骨术中pa骨不稳定性的三维计划患者专用器械的准确性。

目的胫骨或股骨扭转畸形可引起股骨Pat不稳定。既定的手术治疗方法是旋转截骨术，但从术前计划向手术执行的转移可能具有挑战性。特定于患者的器械（PSI）已被证明是重新手术中的有用工具。然而，在股骨和胫骨旋转截骨术中PSI的准确性仍然未知。本研究的目的是评估患有pa股不稳定的患者人群中股骨和胫骨旋转截骨术中PSI的准确性。方法纳入2015年10月至2019年4月在我院门诊因oral股不稳而行PSI股骨或胫骨旋转截骨术的所有患者。可以包括十二个膝盖和十二个sup上con和七个结核上胫骨旋转胫骨截骨术。校正的准确性是根据常规测量值，使用术前和术后CT扫描评估的，在3D中基于相应患者的3D骨骼模型评估的。结果CT测量显示，计划内和完成股骨旋转的绝对值之间的差异为4.8°±3.1°，而胫骨旋转截骨术的旋转角度为7.9°±3.7°，无显着差异（p = 0.069）。关于3D评估，可以观察到在3D角度（p = 0.014）的股骨和胫骨旋转截骨术之间的残留误差有显着差异，而股骨侧的准确性更高。结论PSI在股骨和胫骨旋转截骨术中的应用是安全的外科治疗选择。