Letter to the Editor

Dear Editor: I read with interest the recent publication by McCarthy et al, ‘‘Anatomic Posterolateral Knee Reconstructions Require a Popliteofibular Ligament Reconstruction Through a Tibial Tunnel. ’’ This work is a continuation of intense study over the past decade in this area by Dr LaPrade, the senior author. There is no question of the enormous impact of his study in this area and its contribution to the understanding of the anatomy, biomechanics, and surgical solutions to the clinical problem of posterolateral knee instability. Many of the concepts and techniques I have learned from his work have been applied in my clinical practice with improved surgical outcomes. However, I must take strong issue with the use of the phrase ‘‘require reconstruction of the popliteofibular ligament through a tibial tunnel’’ in the title and the conclusions of this study as to how a tibial tunnel is required in the reconstruction. If one reads the methods and results carefully, the conclusion that a tibial tunnel is ‘‘required’’ is clearly overstated. First, it should be noted that in the study by McCarthy et al, they did not make any attempt to position a graft along the same course of the popliteofibular ligament (PFL) for 1 of the study groups. The group 2 technique featured 2 separate grafts limbs: 1 to reconstruct the lateral collateral ligament (LCL) through the fibular head with the graft brought out the posterior aspect of the fibula and then brought anteriorly and sutured on itself, and 1 separately for the popliteus tendon through a tibial tunnel. There is no graft tissue positioned or oriented as a PFL reconstruction. In fact, I would argue that the study compared a technique that featured 1 technique that attempted to recreate the PFL with 1 that did not. Yet in the methods section, it is stated that the group 2 technique was a modified technique reconstructing the PFL ‘‘where the PFL portion of the anatomic posterolateral knee reconstruction was not passed through the tibial tunnel (group 2) (Figure 3). ’’ Again, one could argue that there was no PFL reproduction in group 2. One could also argue that the reproduction of the popliteus tendon portion of the reconstruction through a tibial tunnel is not anatomic and that using a graft for the PFL also through a tibial bone tunnel is not anatomic. The popliteus muscle and tendon is obviously a myotendinous structure that is attached at the knee in 1 location, the lateral femoral condyle, and not at the posterolateral tibia. Further the PFL comes off the popliteus tendon as it inserts into the fibular styloid posteriorly and there is no attachment to the posterolateral tibia. This may explain the concern some authors have about overconstraint of the knee with the LaPrade method. Second, closer scrutiny of their data is important, summarized in Table 1. Specifically, there was no difference between the 2 study groups for control of external rotation. In fact, group 2 (no PFL arm) curiously had less displacement with external rotation of 0 , 20 , 30 ,and 60 but apparently did not reach statistical significance. With regard to varus rotation, there was statistically more displacement between group 2 and the intact state; however, varus stress in the intact group 2 knees was less than group 1 knees at the start point, suggesting cadaveric variability, reproducibility, and other problems with cadaveric laboratory testing. The absolute amount of varus displacment comparing group 1 and 2 reconstructions was the same. As surgeons, we are constantly exploring techniques that will solve clinical problems in a thorough but easier manner that reduces cost, surgical time, and surgical complexity, and avoids complications without sacrificing the goals and results of the surgery. To this end, we have a described a modification of the fibular-based techniques for posterolateral corner reconstruction that is a combination of the Larsen and LaPrade methods. In this technique, dual femoral tunnels are created to match the femoral insertions of the LCL and popliteus tendons. An important critical feature is the creation of the fibular tunnel in an oblique manner from anterolateral to posteromedial after exposing the distal attachment of the LCL on the fibula. This orients a free graft closely to the normal anatomic pathway of the LCL, over the posterior aspect of the fibular styloid, replicating the pathway of the PFL ligament and then, as it traverses thru the popliteal hiatus, is oriented along the existing remnant of the popliteus tendon to its femoral tunnel. We recently reported in the same journal extremely good outcomes with excellent control of varus rotation and external rotation in a clinical series that featured stress radiography with independent reviewers. Further, the ability to control external rotation and varus rotation has been supported by the biomechanical work of Nau et al in 2005 and a very recent computerized navigational study by Feeley et al. Clinically, I would totally support that the PFL needs to be re-created, but even the authors’ own data are not overwhelming, comparing a technique that attempts to recreate the PFL with 1 that does not. My point is that the very strong conclusion that a tibial tunnel is required to do this is not supported by the method in which they performed the study (no study group with graft oriented along the course of the native PFL and without a tibial tunnel). More importantly, their own results reported do not permit such a strong conclusion.