Novel Technique And Clinical Applications Of Three-dimensional Reconstruction Of The Anterior Cruciate Ligament Graft With Dual-source Computed Tomography

PART Ⅰ Three-Dimensional Reconstruction of the Anterior Cruciate LigamentGraft with Dual-Source Computed Tomography：A Novel TechniqueObjective To explore the scanning technique and parameters in order to three-dimensionally reconstruct anterior cruciate ligament(ACL) graft with dual-sourcecomputed tomography(DSCT).Methods DSCT scanning were performed in30cases of ACL reconstructed knees inattempt to obtain image of the ACL graft after its reconstruction.Results All30grafts were successfully reconstructed by DSCT with our technique andscanning parameters. Extremely clear images were achieved in24cases except in6inwhich the grafts were not so satisfactory documented.Conclusions The graft after ACL reconstruction can be three-dimensionallydocumented by dual-source computed tomography with certain scanning technique andparameters which we recommended. Three-dimensional graft image is significant helpfulto evaluate graft position, improve reconstruction technique and achieve the true anatomicreconstruction eventually. PART Ⅱ Technique and clinical applications of three-dimensional reconstruction ofthe graft position and the tunnel placement after single-bundle anterior cruciateligament reconstruction with dual-source computed tomographyObjective To three-dimensionally document anterior cruciate ligament(ACL) graft andevaluate graft position after single-bundle ACL reconstruction with dual-source computedtomography(DSCT).Methods DSCT scanning were performed with our technique and scanning parametersin76cases of single-bundle ACL reconstructed knees in attempt to obtain image of theACL graft and tunnel placement. Of these76cases, roof-graft impingement was observedin22(defined as impingement group‘), tibial tunnel too posterior was found in21(defined as too posterior group‘), graft position and tibial tunnel were satisfied in33(defined as satisfactory group‘). Graft position and tunnel placement were evaluated,femoral tunnel position(Fx、Fy, Bernard quadrant method), tibial tunnel position (Tx、Ty,Amis-Jakob lines), graft length(L), angles in sagittal plane() and coronal plane()were measured and compared subsequently.Results In impingement group, femoral tunnel position descriptive Fx1, Fy1was22.6%±1.2%、22.4%±1.1%respectively in average; tibial tunnel position descriptive Tx1,Ty1was53.6%±2.0%、34.7%±1.7%respectively in average; the graft descriptive L1,1and1was33.67±3.50mm,44.57±8.85°and67.50±9.78°respectively. In too posteriorgroup, femoral tunnel position descriptive Fx2, Fy2, was22.4%±1.0%、23.7%±1.4%respectively in average; tibial tunnel position descriptive Tx2, Ty2was56.8%±0.8%、50.9±1.3%respectively; the graft descriptive L2,2and2was20.38±3.93mm,69.63±5.39°and65.93±5.39°respectively. In satisfactory group, femoral tunnel positiondescriptive Fx3, Fy3was21.7%±1.0%、23.3%±1.1%respectively in average; tibial tunnelposition descriptive Tx3, Ty3was55.4%±1.6%、43.0%±1.9%respectively; the graftdescriptive L3,3and3was32.31±2.30mm,55.42±3.76°and71.56±5.98°respectively. Statistic analysis showed that there was no significant difference (P>0.05)between any groups at femoral tunnel position, but significant difference(P＜0.05) wasfound in three groups at tibial tunnel position.Tx2and Tx3are significantly higher than Tx1(P＜0.05),and a significant difference was observed between Tx2> Tx3> Tx1.Therewas no significant difference (P=0.422) between L1and L3, but significant difference(P＜0.05) was found between1and3, whereas no significant difference(P=0.333) wasfound between1and3. There was both significant difference(P＜0.05) betweenL2and L3as well as2and3, while no significant difference(P=0.285) was foundbetween2and3.Conclusions The graft and tunnel placement after ACL reconstruction can bethree-dimensionally documented by dual-source computed tomography.Femoral tunnelplacements in three groups are relative constant. There is no difference in graft lengthbetween impingement group (a little too anterior tibial tunnel position but not too far) andsatisfactory group while the graft length in too posterior tibial tunnel group is significantshorter than that in satisfactory group(posterior a lot).The angle of graft in impingementgroup is smaller than in satisfactory group in sagittal plane while no difference in coronalplane.The angle of graft in too posterior tibial tunnel group is bigger than in satisfactorygroup in sagittal plane while no difference in coronal plane. In summary, if we take asatisfactory graft as a standard reference,then a impingement graft is nearly equal withsatisfactory graft in length but a too posterior graft is significant shorter. The impingementgraft shows less verticality but similar obliquity compared with reference.Too posteriorgraft is shorter in length and more vertical but similar obliquity compared with reference.Itcan be used to evaluate the relationship between graft position、graft length、graft anglesand tunnel position. It is significant helpful to improve clinical surgical technique andachieve the true anatomic reconstruction eventually.