Reliability of tibial anterior crest as the anatomical reference of rotating alignment for tibial component in total knee arthroplasty

OBJECTIVE: This study aimed to research whether anterior tibial crest is a reliable anatomical reference for rotational alignment of tibial component in TKA. METHODS: The study included 122 patients who underwent computed tomography angiography (CTA) examination for unilateral lower extremity trauma with normal contralateral lower extremities, including 89 males and 33 females, with an average age of(51.4±16.4) years old(ranged 18 to 81 years old). Picture archiving and communication system (PACS) was used to mark 11 lines including the surgical epicondylar axis (SEA) connecting the most prominent points of the lateral epicondyle and the deepest point of the sulcus on the medial epicondyle of the femur, axis of medial border of patellar tendon (MEPT)connecting the middle of the posterior cruciate ligament (PCL) and medial border of the patellar tendon at the level of a standard tibial cut from 8 mm distal of the lateral tibial joint surface, transverse axis of tibia (TAT) at the level of a standard tibial cut from 8 mm distal of the lateral tibial joint surface, Akagi line connecting the projected middle of the PCL and medial border of the patellar tendon at the tibial attachment, the axis of the medial 1/3 of patellar tendon(M1/3) connecting the projected middle of PCL and the medial 1/3 of the patellar tendon at the patellar tendon attachment level, Insall line connecting the projected middle of the PCL and the medial 1/3 of tibial tubercle, the axis of medial border of tibial tubercle (MBTT) connecting the projected middle of the PCL and medial border of tibial tubercle, as well as the axis of the proximal anterior tibial crest (PATC), axis 1 of the middle anterior tibial crest (MATC1), axis 2 of the middle anterior tibial crest (MATC2) and the axis of the distal anterior tibial crest (DATC) which were marked by connecting the 4 equidistant points on the sharp anterior tibial crest and the projected middle of the PCL. The angles between TAT and SEA as well as the angles between other axes and the perpendicular to SEA were measured. Pairwise differences among the 10 tibial axes were examined using One-Way ANOVA and paired t-test. RESULTS: The angles between the axes of MEPT, Akagi line, M1/3, Insall line, MBTT, PATC, MATC1, MATC2, DATC and the perpendicular to SEA were (-1.6 ±4.5)° , (1.4 ±5.0)° , (10.2±5.1)°, (11.9±5.4)°, (3.6±4.8)°, (12.0±6.9)°, (7.2±8.6)°, (7.1±10.4)°, (6.6±13.5)°, respectively. The angle between TAT and SEA was (4.1±5.3)°. MEPT was external rotation compared to SEA. M1/3, Insall line and PATC were significantly greater than Akagi line, MBTT, TAT (P<0.001). MATC1, MATC2 and DATC were also significantly greater than Akagi line, MBTT axis and TAT (P<0.001). However, MATC1, MATC2 and DATC were also significantly less than M1/3 axis, Insall line and PATC(P<0.01). There were no significant statistical differences between MATC1, MATC2 and DATC(P>0.05). CONCLUSION: The middle tibial anterior crest can be used as a reference for rotational alignment of tibial component in TKA, and its reliability is better than Insall line, but worse than Akagi line, TAT and MBTT.