CORR Insights^®: Does Sequence of Graft Tensioning Affect Outcomes in Combined Anterior and Posterior Cruciate Ligament Reconstructions?

Where Are We Now?

Multiligament knee injuries are highly variable, but most often involve disruption of the ACL and PCL – the so-called “central pivots.” Advances in reconstruction techniques and fixation strategies have led to improved knee stability and patient-reported outcomes [2, 5].

Many controversies persist, however, including the decision about which of the reconstructed ligaments to tension first, and in what position of knee flexion tensioning should be performed. Historically, most authors have recommended securing the PCL graft first at 70º to 90º of knee flexion to obtain appropriate reduction of the tibio-femoral articulation, followed by ACL graft fixation in full extension to ensure the ability of the knee to reach full extension [1, 2, 4]. Because most surgeons are more fearful of PCL failure and subsequent revision, as opposed to ACL failure, fixing the PCL first theoretically should protect the PCL graft.

In the current study by Kim and colleagues [3], the authors challenged “dogma” by comparing PCL first fixation (Group 1) to ACL first fixation (Group 2). Interestingly, both stress radiographs, as well as clinical outcomes, favored the ACL-first fixation group. Specifically, the authors secured the ACL graft in full extension, thereby reducing the tibio-femoral articulation and “locking” it in place. Then, they flexed the knee to 70º to 90º degrees and secured the PCL graft. This technique appears to offer some potential advantages, in that it may serve to: (1) Guarantee the ability to reach full extension, (2) allow maximum tension of the PCL graft against a secured ACL graft, and (3) avoid anterior subluxation secondary to overtensioning of the PCL graft. Not only does this make sense, but the authors have stress radiographs and functional scores to substantiate this tensioning technique.

Where Do We Need To Go?

Several limitations do exist in this study and are appropriately noted by the authors, and these issues should be considered as investigators design the next round of studies on this topic. Firstly, the two groups were not randomized, as the authors retrospectively analyzed patients from two different time periods, over a period of time in which their fixation strategies had changed. Secondly, these patients represented not just with ACL/PCL reconstruction, but also with medial and lateral sided repairs and/or reconstructions. Lastly, no two multiligament knee injuries are the same, and most involve more than just the ACL and PCL. In fact, the majority of multiligament knee injuries also have concomitant meniscus, cartilage, and collateral ligament damage. Because of important heterogeneity in injury patterns, any single study on this patient population becomes difficult to interpret as all of these variables may affect the results in terms of pain, function, and stability.

How Do We Get There?

Specifically, with regards to knee stability post-ACL/PCL reconstruction and the issue of which graft tensioning sequence is optimal, further studies are needed. One way to investigate this particular question is to perform a biomechanical cadaveric study. Using matched paired cadavers, the ACL and PCL ligaments could be sectioned and then reconstructed using identical surgical techniques. Next, the two methods (ACL-first fixation versus PCL-first fixation) could be compared. Another option, but less pure, would be a clinical study on patients that were treated with central pivot (ACL/PCL) reconstruction alone (no meniscal, chondral, or collateral ligament injury) and randomized to one of the two tensioning groups. Ultimately, further large multicenter trials will be needed to truly elucidate the effectiveness of this novel ACL/PCL graft fixation method.