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Anatomical Posterior Cruciate Ligament Transplantation -- A Biomechanical Analysis; Daniel K. Davis et al.; American Journal of Sports Medicine, Baltimore, Maryland; July 2006, Vol 34, pages 1126-1133.Comments: This study shows the urgent need for improved methods of PCL reconstruction. The goal is not only to restore knee stability in the PCL-deficient person, but rather to also restore normal or near-normal knee motion. (Normal knee motion is a complex combination involving roll and glide, and is defined by the cruciate ligaments.) The authors look specifically at femoral rollback, and note that the two current PCL-reconstruction methods (single-bundle and double-bundle) still do not restore normal knee kinematics. The double-bundle method of PCL reconstruction is better than the single-bundle one, but problems remain. The PCL, like the ACL, has a complex, multifascicular construction, and has flared ends. These attributes make the anatomically accurate reconstruction of this ligament an inherently extremely daunting task. Therefore, with any graft constructs and installations, the goal is to come as close to normal knee motion and function (including kinematics and biomechanics) as is realistically possible.

Biomechanical Analysis of a Combined Double-Bundle Posterior Cruciate Ligament and Posterolateral Corner Reconstruction; Jon K. Sekiya et al.; American Journal of Sports Medicine, Baltimore, Maryland; March 2005, Vol 33, pages 360-369.Comments: The authors found that, in combined PCL-PLC-injured knees, posterolateral corner (PLC) reconstruction reduced the loads experienced by the posterior cruciate ligament (PCL) grafts. Anyone with a fully torn PCL and also PLC injury would be well-advised to see out a surgeon who is skilled in reconstructing both structures. The PCL, along with the PLC and also the ACL, are absolutely essential in governing the knee motion. (The PLC also includes the LCL.)

Primary Stability of Three Posterior Cruciate Ligament Reconstruction Procedures: A Biomechanical In Vitro Study; Nobuto Kitamura et al.; Arthroscopy: The Journal of Arthroscopic & Related Surgery; August 2005, Vol 21, pages 970-978.Comments: This lab-type study looks at the primary (i.e. as-installed, with no rehabilitation yet) three different methods of PCL reconstruction. To simulate the cyclical loadings typical of the human knee, and to address the long-standing concern about fatigue-related failure, they carried out tensile testing to 5000 cycles. They found that, just like in ACL reconstruction, the PCL-graft fixation method used is important in terms of strength and fatigue resistance. One attribute that is challenging to test in a laboratory is the propensity of each graft-fixation method to the "bungee-cord effect". And, given the overarching importance of this phenomenon, it would have been nice if the authors would have delved into this in detail. This effect occurs when the graft is fixed only at the ends furthest from the knee-joint line, since it means that the body of the graft inside the bone tunnel is left free to slide with respect to the tunnel walls (and given that all grafts have natural elasticity), thus inhibiting healing and incorporation. Two graft-fixation techniques which tend to be prone to the bungee-cord effect are the Endobutton (used with some sort of tape, such as the Leeds-Keio polyester tape which saw use in this study) and the post-screw. These two methods, not surprisingly, did not bring stellar results in the biomechanical testing. The safest bet is to use the well-proven interference screw and the bone-patellar-tendon-bone graft, a method which brings the overwhelmingly valuable security of bone-to-bone healing. And, traditional interference-screw fixation avoids the bungee-cord worries of the post-screw, the Endobutton, and the polyester tape. Staples, if used to help fix the graft inside the bone tunnels (i.e. not just at the end furthest from the joint), are also a viable option, but on their own they are not able to snugly anchor the graft along its entire length inside the tunnel. Only interference screws can do this.

Posterior Cruciate Ligament Replacement with a Two-Strand Quadriceps Tendon-Patellar Bone Autograft and a Tibial Inlay Technique; Frank Noyes and Sue Barber-Westin et al.; Journal of Bone and Joint Surgery (American Edition); June 2005, Vol 87-A, pages 1241-1252. Comments: This superbly insightful and richly detailed study shows that having two-stranded PCL graft brings vastly improved results, as compared to a single-stranded graft. The authors note that by having a two-stranded graft best reproduces the functions of the distal and posterior thirds of the natural PCL; said portions are biomechanically best located in terms of controlling posterior drawer (i.e. rearwards tibial sliding). Clearly, a serviceable PCL is just as important to knee functioning and longevity as a serviceable ACL.

Posterior Cruciate Ligament Revision Reconstruction, Part 2 – Results of Revision Using a 2-Strand Quadriceps Tendon–Patellar Bone Autograft; Frank Noyes and Sue Barber-Westin; American Journal of Sports Medicine, Baltimore; May 2005, Vol 33, pages 655-665. Comments: This intriguing article delves into the results of the complex-injury knees which underwent revision PCL reconstruction using the two-strand method (which is biomechanically far superior to a single-strand graft). Keeping in mind that the knees in this study had extensive injury histories, the results of the revision reconstructions are impressive. (Dr. Noyes is one of those few doctors who specializes in treating severe, complex knee injuries. He has done pioneering work in many aspects of knee injuries. Sue Barber-Westin, a seasoned clinical researcher of international stature, is one of the most penetratingly insightful people in the entire realm of orthopedics.)

Posterior Cruciate Ligament Revision Reconstruction, Part 1 – Causes of Surgical Failure in 52 Consecutive Operations; Frank Noyes and Sue Barber-Westin; American Journal of Sports Medicine, Baltimore; May 2005, Vol 33, pages 646-654. This careful and thorough investigation into the causes of dozens of PCL-reconstruction failures leaves no stone unturned. An absolute must-read for anyone who has any history of complete or near-complete PCL tearing, or who has undergone PCL reconstruction, or who is planning to undergo PCL reconstruction. Noyes and Barber-Westin are two of the world's most knowledgeable people on the topic of PCL reconstruction (and in fact, on knee issues in general), and the advice they provide translates into suitably penetrating questions to ask one's surgeon prior to surgery. The Knee Library harbours a number of articles first-authored by Noyes, including several which delve into the biomechanically superior two-strand grafting technique.

The Effect of Posterior Cruciate Ligament Deficiency on Knee Kinematics; Martin Logan et al.; American Journal of Sports Medicine, Baltimore; December 2004, Vol 32, pages 1915-1922. Comments: This study looked at six knees with isolated PCL injures and no reconstruction. The authors noted that isolated PCL rupture leads to an increase in the passive sagittal laxity of the medial compartment of the knee. In their discussion, they quote previous research that PCL reconstruction does not produce a better functional outcome than conservative management; however, this quoting is from older research. They make it clear that single-bundle PCL reconstruction (which was still considered current in 2004) does not restore normal knee kinematics and biomechanics. Newer, dual-bundle PCL reconstruction methods, combined with improved understanding of the importance of the PCL and also a better understanding of why past PCL reconstructions often did not bring good results, mean that PCL reconstruction (using the double-bundle method) is now the preferred treatment of choice for fully torn PCLs. The following Noyes-and-Barber-Westin articles provide excellent discussion of these aspects: Noyes-AJSM-May05a.shtml, Noyes-AJSM-May05b.shtml, and Noyes-JBJS-Jun05.shtml. Logan et al. also point out that if the knee is left PCL-deficient for extended periods of time, then fixed deformity (as posterior subluxation) becomes a problem. So, the best solution is to have a fully dysfunctional PCL reconstructed promptly using the double-bundle technique pioneered by Noyes and others, and discussed in Noyes-JBJS-Jun05.shtml, Noyes-AJSM-May05b.shtml, Noyes-AJSM-May05a.shtml,Noyes-AJARS-Oct03.shtml, Stannard-AJSM-Mar03.shtml, Bergfeld-AJSM-Mar01.shtml, and Mannor-AJSM-Nov00.shtml.

In Vivo Function of the Posterior Cruciate Ligament During Weightbearing Knee Flexion; Louis E. DeFrate et al.; American Journal of Sports Medicine, Baltimore, Maryland; December 2004, Vol 32, pages 1923-1928.Comments: This article will be of interest to anyone who has a PCL injury, and especially anyone who is exploring surgical treatments. The importance of reproducing the knee biomechanics as closely as possible is made clear. (The double-bundle method of PCL reconstruction is far superior to the single-bundle method, since it better reproduces the multifascicular structure of the natural PCL.)

Two-Bundle Posterior Cruciate Ligament Reconstruction: How Bundle Tension Depends on Femoral Placement; Jason T. Shearn et al.; Journal of Bone and Joint Surgery (American Edition); June 2004, Vol 86, pages 1262-1270. Comments: This article shows that PCL reconstructions should be done with a double-bundle graft, because single-bundle reconstructions are not able to adequately reproduce the biomechanics of the PCL. The authors note that the location of the second bundle is important: placing it in a middle or distal position brought a notable reduction in the peak tensile loadings in the anterior bundle (which would be the only bundle if this were an obsolete single-bundle PCL graft), as well as what the authors termed cooperative load-sharing (i.e. the two bundles work together to carry the load, and so there is less likelihood of either bundle failing).

Posterior Cruciate Ligament Reconstruction Using Single-Bundle Patella Tendon Graft With Tibial Inlay Fixation: 2- to 10-Year Follow-up; Daniel E. Cooper and Donna Stewart et al.; American Journal of Sports Medicine, Baltimore; March 2004, Vol 32, pages 346-360. Comments: The authors found that single-bundle PCL-reconstruction method (with tibial-inlay fixation) provides reasonably satisfactory results. Be sure to read the October 2003 article by Noyes et al. on the double-bundle PCL-reconstruction method. Although the single-bundle method yields adequate results, the double-bundle method provides a reconstruction that is much closer to the natural anatomy of the PCL -- and therefore knee biomechanics and functioning are greatly improved, thus bringing very tangible benefits for the patient. (The only drawback with the double-bundle method is that it entails more work for the surgeon.)

Arthroscopically assisted quadriceps double-bundle tibial inlay posterior cruciate ligament reconstruction: an analysis of techniques and a safe operative approach to the popliteal fossa; Frank R. Noyes et al.; Arthroscopy: The Journal of Arthroscopic and Related Surgery; October 2003, Vol 19/8, pages 894-905. Comments: This superb and highly insightful article delves deeply into the topic of anatomical optimization of PCL reconstruction. Dr. Noyes is a pioneer in the use of two separate bundles for PCL reconstruction. This method, albeit more demanding for the surgeon to perform, makes the grafted PCL and the resulting knee motion much more similar to that of a normal knee. This article is a must-read for anyone whose knee harbours PCL tearing and for whom reconstructive surgery has been proposed.

Anatomic Reconstruction of the Posterior Cruciate Ligament after Multiligament Knee Injuries: A Combination of the Tibial-Inlay and Two-Femoral-Tunnel Techniques; James P. Stannard et al.; American Journal of Sports Medicine, Baltimore; March 2003, Vol 31, pages 196-202. Comments: This article discusses how to best reconstruct the PCL. Because of the PCL's very pronounced double-bundle structure, reconstructing the PCL with only a single bundle (as is typical for the ACL, which also contains more than one bundle but slightly less markedly so) is inherently inadequate. (Article includes follow-up letter from Dr. Frank Noyes of Cincinnati.)

A Biomechanical Comparison of Posterior Cruciate Ligament Reconstruction Techniques John A. Bergfeld et al.; American Journal of Sports Medicine, Baltimore; Mar/Apr 2001, Vol 29/2, pages 129-136. Comments: The authors describe the anatomic tibial inlay technique of PCL reconstruction, which more closely replicates the anatomic insertion site of the PCL at the rear of the tibia. The method avoids the excessive bending of the graft at the mouth of the tibial bone tunnel, a problem typical of the traditional tunnel-based PCL reconstruction technique. Although this study focuses on the biomechanics of the single-bundle PCL graft, the authors quote previous studies by Race and Harner, which found that the double-bundle PCL-reconstruction method is superior in restoring both normal knee movement and ligament tensile loadings.

Posterior Cruciate Ligament Reconstruction and Rehabilitation Gary J. Calabrese and John A. Bergfeld; Knee Ligament Rehabilitation, edited by Todd S. Ellenbecker. Philadelphia, Pennsylvania: Churchill Livingstone (Harcourt), 2000. Pages 186-193. Comments: This article describes the importance of the PCL, and notes how the PCL interacts with the ACL in limiting knee extension and enabling the knee to lock for standing. Also discussed is surgical reconstruction of the PCL. This article delves into single-bundle reconstruction techniques, but does not mention the new standard of dual-bundle PCL recon. However, many surgeons still perform single-bundle PCL reconstructions, and in fact, many surgeons still do not even do PCL reconstructions at all. (For insight into the benefits and procedural aspects of dual-bundle PCL reconstruction, the following articles are very helpful: Noyes-JBJS-Jun05.shtml and Noyes-AJSM-May05b.shtml.) This chapter nicely describes the implications regarding anterior-posterior shearing forces generated by open-kinetic-chain exercises and closed-kinetic-chain exercises. A sound rehabilitation protocol will include both varieties of exercises at the appropriate stages.

Two-bundle posterior cruciate ligament reconstruction: An in vitro analysis of graft placement and tension, Dana A Mannor; The American Journal of Sports Medicine, Baltimore; Nov/Dec 2000, Vol 28/6, p. 833. Comments: Mannor et al. undertook the task of determining the influence of the femoral-attachment location of a split-Y-configuration PCL graft on the load-handling/sharing capabilities of said graft's two component branches. Also studied was the biomechanics behind how the dual bundles, acting both in tandem and individually, resisted the various modes of forcing expected of the PCL. (The PCL is taut in flexion, whereas the ACL is taut when the knee is fully extended. The PCL's major role is to prevent rearwards sliding of the tibia with respect to the femur. The ACL, meanwhile, is responsible for controlling forwards tibial sliding. Both cruciate ligaments are involved in controlling other modes of forcing and defining the linkage-type motion of the knee. For example, the ACL is responsible for constraining nearly all of the twisting that the knee is called upon to deal with. While PCL deficiency has historically been viewed as less serious than ACL deficiency, the increasingly-clearly-revealed biomechanical importance of the PCL makes tendon-graft reconstruction just as important to long-term knee health as it does for the notorious ACL.)

The natural history of acute, isolated, nonoperatively treated posterior cruciate ligament injuries: A prospective study , K. Donald Shelbourne; The American Journal of Sports Medicine, Baltimore; May/Jun 1999, Vol 27/3, p. 276. Comments: Shelbourne notes that PCL injuries generally occur without the foot bearing weight, thus accounting for at least one reason why PCL injuries are not as often accompanied by meniscal tearing as are ACL injuries. (Meniscal tears are most-often caused by compression applied in conjunction with twisting.) In this study, he indicates that the results suggest that athletically active patients with acute isolated conservatively-treated posterior-cruciate-ligament tears attained a level of objective and subjective knee function that was not contingent upon the severity of posterior laxity. Physical tests of PCL-deficiency-caused looseness were not predictive of the patients' subjective reports of knee-functioning.

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