对比前、后参考系统全膝关节置换术（TKA）中股骨前皮质切割的发生情况，并通过计算截骨时因锯片在截骨导向器导槽内上下摆动产生的截骨偏差以探寻前皮质切割发生的原因。

选取2015年9月至2020年12月在北京大学国际医院骨科因原发性膝关节骨关节炎行初次TKA的连续病例资料并进行回顾性分析。依据股骨假体的测量方式，将患者分为前参考组和后参考组，对比2组术后膝关节侧位X线的前皮质切割发生情况。测量截骨导向器的导槽深度和高度、摆锯锯片厚度和切入骨内长度，计算锯片的最大摆动幅度和前皮质最大切割深度。

患者共纳入膝195例、239例，前参考组膝107例，后参考组膝132例。前、后参考组的前皮质切割发生率分别为26.2%、18.9%；Tayside分级Ⅲ级及Ⅳ级的发生率分别为4.7%、6.1%。2组间前皮质切割发生率（χ²=1.789，P=0.181）、Ⅲ级及Ⅳ级前皮质切割发生率（χ²=0.221，P=0.638）的差异无统计学意义。当锯片切入骨内长度为5 cm时，前参考组的锯片最大摆动幅度为2.98 mm，前皮质最大切割深度为0.75 mm；后参考组的锯片最大摆动幅度为3.15 mm，前皮质最大切割深度为0.80 mm。

在避免前皮质切割方面，前参考系统并未比后参考系统更具有优势，原因在于后参考系统股骨假体的特殊设计。包括锯片在导槽内上下摆动在内的多种因素所引起的截骨偏差在前皮质切割发生中起到了重要作用。

To compare the incidence of anterior femoral notching in total knee arthroplasty (TKA) using the anterior versus posterior reference system, and to investigate the reason of anterior femoral notching by calculating the cutting error caused during osteotomy by the oscillation of saw blade through the guide-slot.

Patients who underwent TKA for primary osteoarthritis between September 2015 and December 2020 were enrolled in this study. The patients were divided into either an anterior reference group or a posterior reference group according to the femoral component sizing method used. The incidence of anterior femoral notching was compared between the two groups according to the Tayside classification on postoperative lateral X-ray images of the knee joint. The height and depth of the slot as well as the thickness and the cutting length of saw blade were measured. The maximum oscillatory amplitude of blade and the maximum cutting depth of the anterior cortex were calculated using the measured value of the slot height, slot depth and saw blade thickness.

A total of 195 patients (239 knees) were enrolled in the study with 107 and 132 knees in the anterior and posterior reference groups, respectively. There was no significant difference between the two groups in the incidence of general anterior femoral notching (26.2% vs 18.9%, χ²=1.789, P=0.181) or the incidence of severe anterior femoral notching (Tayside grades Ⅲ and Ⅳ; 4.7% vs 6.1%, χ²=0.221, P=0.638). The maximum oscillatory amplitude of blade and the maximum cutting depth of the anterior cortex at a cutting length of 5 cm were 2.98 mm and 0.75 mm in the anterior reference group and 3.15 mm and 0.80 mm in the posterior reference group, respectively.

The anterior reference system does not seem to be definite advantages over the posterior reference system in avoiding anterior femoral notching during TKA. The reason may be the special design of the femoral prosthesis of the posterior reference system. The cutting error caused by the oscillation of saw blade in the guide-slot during osteotomy and other factors may play an important role in leading to anterior femoral notching.