Extract
The iliotibial band often is a deforming force in the valgus knee, and sometimes it must be released or elongated to establish normal stability of the knee during total knee arthroplasty1-4. This structure is primarily ligamentous; it attaches to the iliac crest and then passes over the hip and knee to attach to the patella and then to the tibia and fibula below the knee.This study of the iliotibial band was done to delineate its attachments about the lateral side of the knee, to describe its function in flexion and extension, and to develop an effective surgical procedure to lengthen it in patients with ligament imbalance.
The iliotibial band often is a deforming force in the valgus knee, and sometimes it must be released or elongated to establish normal stability of the knee during total knee arthroplasty1-4. This structure is primarily ligamentous; it attaches to the iliac crest and then passes over the hip and knee to attach to the patella and then to the tibia and fibula below the knee.
This study of the iliotibial band was done to delineate its attachments about the lateral side of the knee, to describe its function in flexion and extension, and to develop an effective surgical procedure to lengthen it in patients with ligament imbalance.
Twenty human cadaver knees were dissected to identify the pertinent anatomic and surgical features of the iliotibial band and to evaluate its function during flexion and extension of the knee. The skin and subcutaneous tissue were removed, and the iliotibial band and its distal attachments were dissected to their sites of attachment on the patella, tibia, fibula, and biceps femoris muscle and tendon. The femur was clamped in a vise and the knee was flexed and extended as the various parts of the iliotibial band were observed, palpated, and photographed. Finally, the knee was opened through a medial parapatellar arthrotomy and a probe was inserted. An attempt was made to access the anterior, middle, and distal portions of the iliotibial band through this medial approach to the knee. The posterior half of the iliotibial band was incised in line with its fibers, and the posterior portion of the iliotibial band was transected extrasynovially and separated from its attachment to the biceps femoris muscle and tendon. The behavior of the remaining anterior portion was then observed as the knee was flexed and extended. To demonstrate the clinical use of the posterior iliotibial band release, a single clinical case is illustrated.
Source of Funding
The internal source of funding for this study was the Missouri Bone and Joint Research Foundation, a not-for-profit research facility directed by Dr. Whiteside. The clinical case used in this article is from Dr. Whiteside's clinical practice, Missouri Bone and Joint Center, but the Center did not provide funding for this project.
The iliotibial band was found to trifurcate into three distinct bands: one attaching to the lateral edge of the patella, one attaching to the Gerdy tubercle, and one attaching to the fibula and the biceps femoris. The anterior band, attached to the patella, tightened in flexion; the central band, attached to the Gerdy tubercle, tightened in midflexion; and the posterior band, attached to the fibular head and biceps femoris, tightened in full extension. Only the anterior half of the iliotibial band could be accessed fully through an intra-articular approach. The anterior portion of the central band, but not the posterior portion, could be accessed through an intra-articular approach. None of the portion of the posterior band that attaches to the fibular head and biceps femoris could be accessed through an intra-articular approach without passing through the popliteus tendon and the lateral collateral ligament (Figs. 1 through 8).
Figures 9 through 17 depict how selective release of the iliotibial band can restore knee stability during total knee arthroplasty.
The iliotibial band functions as a primary lateral stabilizing ligament of the knee, and it is especially important during full extension of the knee4,5. However, its attachments to the patella prevent the iliotibial band from shifting posteriorly in flexion and thus impart a curvature to its anterior portion, providing a lateral stabilizing effect on the knee during flexion. The posterior portion of the iliotibial band is attached by fibers to the biceps femoris tendon and aponeurosis as well as to the fibular head. The posterior half of the iliotibial band tightens in extension, and the fibers that extend farther posteriorly also tighten, thus preventing the entire complex from shifting anteriorly while providing lateral stability to the knee in extension.
The complex series of functions performed by the iliotibial band give it an important role in stabilizing the knee in flexion and extension. When part of the iliotibial band contributes to the deformity in the valgus knee, release of the iliotibial band should be done in a manner that slackens only its pathologically tight structures and not its normal components. If the knee is tight laterally only in extension, then only the posterior fibers should be released. If the knee is tight laterally only in flexion, then only the anterior fibers should be released.
In a valgus knee, the lateral bone structure is deficient and the posterior portion of the iliotibial band often is contracted. When normal anatomic structure and alignment are restored to the knee, this tight posterior segment holds the iliotibial band posteriorly, augmenting the effect of the anterior portion of the iliotibial band and even tightening the lateral patellar retinaculum and pulling the patella laterally6.
Release of the posterior portion of the iliotibial band is a conservative procedure that is done to restore balance to the knee, but access to the posterior iliotibial band can be a surgical challenge. An intra-articular approach to the iliotibial band requires transection of the synovial membrane1-3,7. Although good results have been reported with this inside-out technique1,3,7, our dissections show that posterior iliotibial band release endangers the popliteus tendon and the lateral collateral ligament. An extra-articular release of the iliotibial band is performed through dissection over the outer surface of the patella to expose the iliotibial band. This approach allows complete release of the iliotibial band without opening the synovial membrane, and does not endanger the other lateral ligaments of the knee. An additional advantage to this approach is that it allows for the selective release of the anterior, central, and posterior portions of the iliotibial band.
In summary, the iliotibial band is a complex lateral structure that functions in both flexion and extension of the knee joint. Complete or partial release of the iliotibial band is best done through an extra-articular approach to the knee joint, proximal to the joint line. 
Note: The authors thank Brian Katerberg, BS, for technical assistance in the laboratory, and Diane Morton, MS, for assistance with manuscript preparation.
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