Comparison of patient-specific distal femoral cutting guide and conventional instruments in total knee arthroplasty / 中华骨科杂志

ABSTRACT

Objective To design a patient-specific distal femoral cutting guide for total knee arthroplasty using rapid prototyping and 3D printing technology and compare with conventional instrumentation.Methods A prospective self-control study was performed in 32 patients who underwent bilateral total knee arthroplasty between March 2015 and November 2015 in our department.The bilateral knee joints were randomly divided into patient-specific guide group and traditional surgery group.The patient-specific guide group obtained CT data of the lower extremities preoperatively.Patient-specific distal femoral cutting guides were designed and manufactured using rapid prototyping and 3D printing techniques.The traditional surgery group were performed using conventional instrumentation.The operation time of the two groups was recorded,and the amount of distal femoral osteotomy was measured.Postoperative alignments were measured including the angle of the lower limb mechanical axis angle (hipknee-ankle Angle,HKA),the mechanical lateral distal femoral angle (mLDFA),and the mechanical proximal tibial angle (mMPTA).In different follow-up points Hospital for Specific Surgery scores of the knee were recorded.Results In the coronal position,the postoperative mLDFA was 90.34°± 1.6° in the patient-specific guide group and 91.37°± 1.8° in the conventional surgery group.The difference between the two groups was statistically significant (t=-2.452,P=0.020).In the patient-specific guide group,the HKA angle was 0.36°±2.35°,and the conventional surgery group was 0.87°±1.85°.The difference between the two groups was statistically significant (t=-2.332,P=0.043).If preoperative mLDFA≤93°,there was no significant difference in postoperative mLDFA between the two groups (t=-1.409,P ＞ 0.05).If preoperative mLDFA ＞ 93°,there was a significant difference in postoperative mLDFA between the two groups (t=-4.145,P=0.004).In addition,the operation time of the patient-specific guide group was significantly shorter (t=-2.425,P ＜ 0.05),but the two groups did not have significant functional differences in the early postoperative period.Conclusion The 3D-printed patient-specific distal femoral cutting guide can significantly shorten the operation time and improve postoperative alignments.It is simple to operate.However,large sample sizes and long-term follow-up studies are still needed to verify their long-term effects.