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Letter to the Editor |
Portsmouth, Virginia
Dear Editor:
It was with great interest that we read the article by LaPrade et al titled "An Analysis of an Anatomical Posterolateral Knee Reconstruction: An In Vitro Biomechanical Study and Development of a Surgical Technique" (September 2004, pages 1405–1414). Dr LaPrade has contributed significantly to the advancement of this topic, and this article certainly is another example of new knowledge contributing to our understanding of this complex but very important clinical area.
However, we have 2 concerns with his technique. Our primary concern centers on the popliteofibular ligament reconstruction with the graft traversing from the posterolateral fibula to the posterolateral tibia. The popliteofibular ligament is truly the fibular connection of the popliteus tendon, which attaches to the femur as well as dynamically to the tibia. The first 2 limbs of the described reconstruction anatomically reconstruct the lateral collateral ligament (LCL) and the popliteus tendon. However, the third limb of the reconstruction serves more to reinforce the posterior proximal tibiofibular joint than it does to re-create the popliteofibular ligament. The described reconstruction clearly reproduces the static popliteus tendon attachment from the tibia to the femur, but there is no connection between the fibula and the femur, which is likely the more important of the 2 connections. This factor may be an additional reason the varus laxity at 30° was not more similar to the intact state.
Our secondary concern centers on the fibular tunnel. The fibular tunnel is drilled shallow, such that some loosening of the proximal fibular styloid occurred with mechanical testing. We too have found this loosening to be a potential problem clinically when attempting to create one fibular tunnel connecting the popliteofibular ligament and the LCL. We have described a similar technique reconstructing all 3 key elements of the posterolateral corner (LCL, popliteus tendon, popliteofibular ligament) using a bifid Achilles tendon.1 Our fibular tunnel enters at the anatomical site of the popliteofibular attachment and exits the anterior fibula distal to the normal attachment of the LCL. This position allows a large amount of proximal fibular bone to strengthen our construct. To re-create our anatomical fibular attachment of the LCL, we then bring the graft back on itself and suture fix this to the native attachment of the LCL while reinforcing it with a suture anchor. This procedure adequately fixes the fibular attachment of the LCL anatomically without compromising the fibular tunnel stability. We believe that the added strength of the proximal fibular bone is crucial to our initial fixation.
Again, we would like to congratulate Dr. LaPrade on his excellent article and study, which brings an objective biomechanical basis to a topic that for too long has been addressed only by anecdotal reports, technical notes, and book chapters with expert opinion. It is with great anticipation that we await the results of his prospective clinical study.
REFERENCE
Professor, University of Minnesota
Professor, University of Oslo
University of Oslo
We appreciate Dr Sekiya et al’s concerns and thoughtful insights about our procedure.*
First, in regard to their concerns about the fibular tunnel, neither of our sites have noted any in vivo clinical problems with drilling this tunnel. Between our 2 sites, we have performed more than 120 of these reconstructions to date. In our collective experience, we have had no problems with reaming this tunnel, and we would not recommend reaming this tunnel more distally for 2 reasons. First, it would result in the anatomical attachment site on the fibula being moved to a nonanatomical location. Second, the common peroneal nerve is located very close to the neck of the proximal fibula. Dropping the tunnel down only 1 to 2 cm distally could cause this reconstructive graft to be apposed against the common peroneal nerve, which could cause irritation and potential problems during the surgical exposure. As such, we would recommend that this tunnel be drilled through the anatomical attachment sites of these 2 structures. In those patients who may have osteopenic bone, it may be prudent to drill smaller tunnels and to enlarge these tunnels with dilators if necessary.
In terms of their concerns about the popliteofibular ligament portion of our reconstruction, we would reiterate our discussion in our article regarding the fact that buckle transducers placed on the popliteofibular ligament both in its native state and during the surgical reconstruction demonstrated that forces were generated in the reconstructive state that were similar to the native static function of the popliteofibular ligament. It is well recognized that the main structures preventing increases in joint motion of the posterolateral knee, which have been identified during biomechanical testing at multiple different centers, are the fibular collateral ligament, popliteus tendon, and popliteofibular ligament. It is important to recognize the popliteofibular ligament does have an important static role in preventing posterolateral rotation of the knee. We did trial a procedure in which the popliteus tendon was routed directly to the fibular head but felt this was a nonanatomical sling procedure, and it proved to be less stable in these patients than our current follow-up results in our ongoing prospective study have found.
We believe that a lot of the confusion regarding the role of the popliteofibular ligament is owing to the many different names that have been used to describe it over the past century. Although many authors have noted the presence of the popliteofibular ligament,
this structure was omitted from the update of the Nomina Anatomica11 by the International Congress of Anatomists in 1956. Because of this, many authors did not formally recognize the popliteofibular ligament, and it resulted in many different names being given to this structure. The most commonly referred to name for this structure was the arcuate ligament. In fact, one of the classic articles on posterolateral anatomy reported that the innermost lamina of their posterolateral structures, which they called a "Y-shaped arcuate ligament," spanned the junction between the fibular head and the popliteus and was located anterior to the inferior lateral genicular artery. The authors’ description of this structure, especially in relation to the inferior lateral genicular artery, would confirm that they were referring to the popliteofibular ligament.8,15,19 It was felt from many different centers, and it is still quoted from the podium at some meetings today, that the arcuate ligament is the key to reconstructing the posterolateral knee. It is also very important to recognize that a follow-up article that reported on the anatomy of the popliteofibular ligament in detail,10 from the same research center as this classic work by Seebacher et al,14 stated that this work, and other previous studies from their center,3,14 did not recognize the existence of the popliteofibular ligament at the time and had named it the arcuate ligament. With this in mind, it would appear that the existence of the popliteofibular ligament has been noted by many centers all along, and the confusion regarding this lack of recognition was directly related to differing nomenclature. As such, we strongly recommend that the term arcuate ligament not be used to describe posterolateral knee structures, as its primary description in the past was to describe the popliteofibular ligament.
In any event, we do recognize that a posterolateral reconstruction procedure needs to reproduce the static function of these 3 structures. We are working on trying to evolve our techniques, such that the reconstructive grafts can be passed around the remaining musculotendinous junction of the popliteus in an attempt to restore some dynamic function to this complex. We have attached an MRI figure (available in the online version of this article at www.ajsm.org/cgi/content/full/33/8/1250/DC1) from one of our recent reconstructions, which demonstrates that the popliteofibular ligament portion of this reconstruction graft does course along the native position of the popliteofibular ligament and does not result in a tenodesis of the proximal tibiofibular joint.
In summary, we believe that the popliteofibular ligament portion of this reconstruction procedure is important to restore the normal static function of these 3 important posterolateral knee stabilizers. We thank Dr Sekiya et al for their kind comments.
Sincerely,
FOOTNOTES
* A similar letter was received from P. Frier of South Africa. Because both letters raised similar concerns, only one was chosen for publication. 
References 1, 2, 4, 5–7, 9, 10, 12, 13, 15–18, 20.
REFERENCES
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