We read with this article with great interest. This article provides very important information regarding balancing the flexion gap during total knee arthroplasty and is very helpful in our daily practice. However, we have a comment regarding Figures 1-B and 10 in their article. These figures indicate that, in the flexed knee, the anterolateral (AL) bundle of the posterior cruciate ligament (PCL), which originates from the roof of the intercondylar notch, runs vertically and passes across deeper to the posteromedial (PM) bundle of PCL, which originates from the side wall of the intercondylar notch, before getting attached to the tibia. Amis et al.[2] described the anatomy of the two bundles of PCL: the AL bundle is slack in extension and tight in flexion, whereas the PM bundle is tight in extension and slack in flexion. Therefore, we were interested in the role of the two bundles of PCL in balancing the flexion and extension gap during total knee arthroplasty. To investigate the role of these bundles, they were first identified. Identification of the two bundles was easy because the AL bundle originates vertically from the roof of the intercondylar notch whereas the PM bundle originates obliquely from the side wall of the intercondylar notch at its femoral attachment; moreover, the PM bundle is much thinner than the AL bundle. Our investigation showed that the PM bundle passes across deeper to the AL bundle. This fact is also confirmed in Figure 4 and Figure 1-C in the articles by Amis et al.[2] and Tajima et al.,[3] respectively. As Lombardi Jr et al.[1] described, common techniques for balancing PCL are release of PCL from its femoral or tibial attachments. We prefer femoral release of PCL because it can be performed even after the femoral and tibial trial components are fixed, when the AL or the PM bundle can be selectively released. We believe that the knowledge of which bundle of PCL is located more anteriorly at the tibial insertion side is very important when releasing PCL at its tibial attachment. The AL bundle can be released first according to Fig. 1 in our letter, but the PM bundle should be released first according to Figures 1-B and 10 in the article by Dr. Lombardi Jr et al. Are these figures accurate? REFERENCES: [1] Lombardi Jr AV, Berend KR, Aziz-Jacobo J, Davis MB. Balancing the flexion gap: Relationship between tibial slope and posterior cruciate ligament release and correlation with range of motion. J Bone Joint Surg Am. 2008; 90: 121-32. [2] Amis AA, Gupte C, Bull AMJ, Edwards A. Anatomy of the posterior cruciate ligament and the meniscofemoral ligaments. Knee Surg Sports Traumatol Arthrosc. 2006; 14: 257-63. [3] Tajima G, Nozaki M, Iriuchishima T, Ingham SJM, Shen W, Smolinski P, Fu FH. Morphology of the tibial insertion of the posterior cruciate ligament. J Bone Joint Surg Am. 2009; 91: 859-66. EDITOR’S NOTE: The authors wished to post a figure with this comment; however, the commenting feature does not permit this. The figure is available from the authors of the comment. The legend of their figure is as follows: Fig. 1: The anterolateral and the posteromedial bundle were separated during total knee arthroplasty (in the flexed right knee).