Posterolateral corner injuries of the knee: anatomy, diagnosis, and treatment

Injuries to the posterolateral corner of the knee continue to be a complex problem for orthopedic surgeons. Early recognition and treatment are important factors in the patient's long-term outcome. To properly treat these patients, the surgeon must have a clear understanding of the anatomic relationships amongst the structures in the posterolateral knee. This knowledge combined with a thorough physical examination and imaging studies, allows the surgeon to make the correct diagnosis and devise an appropriate treatment plan. This article will discuss the anatomy, diagnosis, and treatment options to improve the surgeon's understanding of posterolateral knee injuries. The senior author's technique for anatomic reconstruction of the posterolateral corner of the knee and the rehabilitation protocol are described.     

MRI of the posterolateral corner injury: a concise review

The posterolateral corner of the knee represents a complicated area of anatomy and function. Failure to recognize injury to the posterolateral structures in the acute setting can result in long-term disability. Magnetic resonance imaging (MRI) provides a noninvasive evaluation of such structures. A systematic and simplified approach to the MRI evaluation of posterolateral corner injury can aid in diagnosis and subsequent surgical consideration.     

The posterolateral corner of the knee

OBJECTIVE: The purpose of this article is to review the clinical importance and MRI appearances of injuries to the posterolateral corner of the knee. CONCLUSION: Injuries to the posterolateral corner structures of the knee can cause significant disability due to instability, cartilage degeneration, and cruciate graft failure. Becoming familiar with the anatomy of this region can improve one's ability to detect subtle abnormalities and can perhaps lead to improvements in diagnosing and understanding injuries to this area.     

The anatomy and biomechanics of thelateral aspect of the knee

The lateral and posterolateral aspects of the knee are complex and often confusing anatomic regions. The structures that comprise the lateral aspect of the knee are the lateral knee retinaculum, which is comprised of the iliopatellar band, and iliotibial tract. The complicated posterolateral corner is an integrated complex that includes the lateral collateral ligament, the popliteus tendon, the fabellofibular ligament, the arcuate ligament, the popliteofibular ligament, and the short lateral ligament. It is only recently that a much clearer understanding of the anatomic structures of the lateral and posterolateral aspects of the knee have been delineated. As a result a more accurate determination of the biomechanical contributions of each these structures has occurred. The lateral collateral ligament is the primary restraint to varus rotation at all degrees of knee flexion. The posterolateral structures, of which the popliteofibular ligament has been shown to play a major role, are also a primary restraint to external rotation. These same structures play a secondary role in the control of anterior and posterior translation of the knee. It is the hope that this improved understanding of the anatomy and biomechanics of the lateral and posterolateral aspects of the knee will translate into improved clinical management of the instabilities that are often so debilitating and clinical challenging.     

Anatomical variations in the anatomy of the posterolateral corner of the knee

This cadaveric study of 22 knees described the anatomy of the deeper structures of the posterolateral corner, the popliteus–tendon complex, arcuate ligament complex, the popliteofibular ligament, and the coronary ligament. Most variations occurred in the popliteofibular ligament; the variations and the different nomenclatures used in the literature for these structures make it difficult to diagnose and repair injuries to them. Untreated injuries may result in chronic functional instability to the posterolateral corner of the knee.     

Gerdy tubercle osteotomy in surgical approach of posterolateral corner of the knee

Posterolateral corner (PLC) injuries of the knee are uncommon injury patterns that may result in significant degrees of functional disability. When surgery is necessary to address this injury a good knowledge of anatomy and a good surgical exposure is the mainstay. This report reviews the complex anatomy of the posterolateral corner (PLC) of knee and describes the osteotomy of Gerdy tubercle as a technical variant to approach this anatomical region. This surgical step allowing a good mobilisation of the multiple layers of ilio-tibial tract from distal to proximal makes an excellent exposure of the PLC structures with absence of morbidity.     

Anatomy and biomechanics of the lateral side of the knee

The posterolateral corner (PLC) of the knee is a critical element for a functional lower extremity. It consists of an array of complex ligamentous and musculotendinous structures. The primary function of the PLC is to resist varus and external rotation and posterior translation of the tibia. Injuries to these structures can cause significant disability and compromise activities of daily living and work, recreational, and sporting activities. A thorough understanding of the complex anatomy and biomechanics of the PLC will aid the clinician in this challenging diagnostic and therapeutic problem. The first section of this paper describes the anatomy of the PLC of the knee focusing on the intricate insertion sites of the individual structures. The second section discusses how the anatomy influences the biomechanics of the PLC.     

MR imaging,MR arthrography,and specimen correlation of the posterolateral corner of the knee: an anatomic study

OBJECTIVE: We sought to evaluate the anatomy of the posterolateral aspect of the knee with anatomic dissection, MR imaging, MR arthrography, and sectional anatomy. MATERIALS AND METHODS: We assessed the posterolateral corner of the knee during dissection of one gross anatomic specimen. MR imaging and MR arthrography were performed in seven additional knee specimens. T1-weighted spin-echo MR images were obtained in the standard imaging planes as well as in the coronal oblique plane. The specimens underwent T1-weighted spin-echo MR imaging after administration of intraarticular contrast material and were sectioned into planes corresponding to those of the MR images. RESULTS: At anatomic dissection, the following posterolateral structures were identified: the arcuate ligament (medial and lateral limbs), fabellofibular ligament, popliteofibular ligament, popliteus tendon and its two posterior attachments to the lateral meniscus, fibular collateral ligament, direct and anterior arms of the tendon of the long head of the biceps femoris muscle, and direct and anterior arms of the tendon of the short head of the biceps femoris muscle. Correlation of MR imaging and anatomic findings showed that the popliteofibular ligament and oblique popliteal ligament were found in 57% and 100% of specimens, respectively. At least one of the two limbs of the arcuate ligament was identified in 71% of specimens. The fabellofibular ligament was not identified on MR images in any of the specimens. The anteroinferior and posterosuperior popliteomeniscal fascicles were identified in all specimens. CONCLUSION: The posterolateral corner of the knee comprises complex and variable anatomic structures. Recognition of these variations is important in the assessment of MR images of the knee.     

Novel approach for reconstruction of the posterolateral corner using a free tendon graft technique

Injuries to the lateral collateral ligament (LCL) and posterolateral corner of the knee, particularly when combined with anterior cruciate or posterior cruciate ligament injuries, can result in profound symptomatic knee instability. Although many surgical improvements have been made in the reconstruction of anterior and posterior cruciate ligament injuries, reconstruction of the posterolateral corner has had less predictable results, with residual pathologic laxity especially in the chronic situation. This has stimulated many surgeons to recommend acute repair of posterolateral knee injuries. This article will briefly review the relevant surgical anatomy, present a summary of current reconstructive techniques for the posterolateral corner, and describe our preferred method for anatomic reconstruction of the posterolateral corner for chronic instability of the knee by recreating the LCL and popliteofibular ligament using either autogenous or allograft soft tissue and an interference screw technique. We do not use a transtibial tunnel but re-orientate the transfibular tunnel and utilize 2 femoral tunnels an the attempt to recreate the LCL and popliteus tendon. In a small clinical series, this has proven to restore varus rotation and external rotation patholaxities with a high degree of predictability.     

MRI of the posterolateral corner of the knee: normal appearance and patterns of injury

The posterolateral corner (PLC) of the knee is a complex area, previously poorly understood by radiologists. Numerous structures make up the PLC, whose evaluation is difficult because of the variable presence of the individual components, their intimate and commonly overlapping insertions, and their oblique course on traditional imaging planes. The clinical relevance of PLC injuries, especially the infrequently repaired "minor" components, adds to the confusion. Our purpose is to review the anatomy, imaging, clinical evaluation, and treatment options for PLC injuries.     

Surgical treatment of chronic posterolateral rotatory instability of the knee using capsular procedures

Chronic posterolateral rotatory instability of the knee was introduced as a diagnostic classification by Hughston and associates in the early 1970s and occurs as a result of dysfunctional healing of a strained arcuate complex, causing a patulous posterolateral capsuloligamentous complex to exist. This capsular redundancy allows varying degrees of recurvatum and adduction instability during single-limb stance. Eradication of the redundant pouch with a capsular shift-type reconstruction has been shown to eliminate the instability and hold up under long-term follow-up studies. Understanding the complex normal and injured anatomy of the posterolateral corner of the knee is essential for effective reconstruction of this instability.     

Biomechanical analysis of a combined double-bundle posterior cruciate ligament and posterolateral corner reconstruction

BACKGROUND: Failure to address both components of a combined posterior cruciate ligament and posterolateral corner injury has been implicated as a reason for abnormal biomechanics and inferior clinical results. HYPOTHESIS: Combined double-bundle posterior cruciate ligament and posterolateral corner reconstruction restores the kinematics and in situ forces of the intact knee ligaments. STUDY DESIGN: Controlled laboratory study. METHODS: Ten fresh-frozen human cadaveric knees were tested using a robotic testing system through sequential cutting and reconstructing of the posterior cruciate ligament and posterolateral corner. The knees were subjected to a 134-N posterior tibial load and a 5-N.m external tibial torque at multiple flexion angles. The double-bundle posterior cruciate ligament reconstruction was performed using Achilles and semitendinosus tendons. The posterolateral corner reconstruction consisted of reattaching the popliteus tendon to its femoral origin and reconstructing the popliteofibular ligament with a gracilis tendon. RESULTS: Under the posterior load, the combined reconstruction reduced posterior translation to within 1.2 +/- 1.5 mm of the intact knee. The in situ forces in the posterior cruciate ligament grafts were significantly less than those in the native posterior cruciate ligament at all angles except full extension. Conversely, the forces in the posterolateral corner grafts were significantly higher than those in the native structures at all angles. Under the external torque with the combined reconstruction, external rotation as well as in situ forces in the posterior cruciate ligament and posterolateral corner grafts were not different from the intact knee. CONCLUSIONS: A combined posterior cruciate ligament and posterolateral corner reconstruction can restore intact knee kinematics at time zero. In situ forces in the intact posterior cruciate ligament and posterolateral corner were not reproduced by the reconstruction; however, the posterolateral corner reconstruction reduced the loads experienced by the posterior cruciate ligament grafts. CLINICAL RELEVANCE: By addressing both structures of this combined injury, this technique restores native kinematics under the applied loads at fixed flexion angles and demonstrates load sharing among the grafts creating a potentially protective effect against early failure of the posterior cruciate ligament grafts but with increased force in the posterolateral corner construct.     

Anterior rim tibial plateau fractures and posterolateral corner knee injury

The aim of this study was to review MRI findings of clinically suspected posterolateral corner knee injuries and their associated internal derangements. Sixteen knees in 15 patients who had evidence of a posterolateral corner knee injury on the physical exam underwent MRI to evaluate the posterolateral corner of the knee and to look for associated injuries. Two musculoskeletal radiologists reviewed the scans. Surgery was performed on 10 of the knees. Tibial plateau fractures were present in 6 knees; 5 of the fractures were anteromedial rim tibial plateau fractures. The popliteus muscle was injured in 13 knees and the biceps femoris in 6 knees. The lateral collateral ligament was ruptured in 12 knees. The posterior cruciate ligament was completely ruptured in 7 knees and avulsed from its tibial attachment in 1 knee. Eleven knees had a complete anterior cruciate ligament rupture. The anterior cruciate ligament was edematous without complete disruption of all fibers in 3 knees. There was excellent correlation between the MRI results and operative results in regard to the presence of a posterolateral corner injury of the knee (9 of the 10 knees had a posterolateral corner injury). In our study MRI readily detected posterolateral corner injuries. Posterolateral corner injuries of the knee are frequently associated with a variety of significant injuries, including cruciate ligament tears, meniscus tears, and fractures. Fractures of the peripheral anteromedial tibial plateau are not common; however, given their relatively common occurrence in this study, they may be an indicator of a posterolateral corner injury to the knee.     

Posterolateral supporting structures of the knee: findings on anatomic dissection, anatomic slices and MR images

In this article we study the ligaments and tendons of the posterolateral corner of the knee by anatomic dissection, MR-anatomic correlation, and MR imaging. The posterolateral aspect of two fresh cadaveric knee specimens was dissected. The MR-anatomic correlation was performed in three other specimens. The MR images of 122 patients were reviewed and assessed for the visualization of different posterolateral structures. Anatomic dissection and MR-anatomic correlation demonstrated the lateral collateral, fabellofibular, and arcuate ligaments, as well as the biceps and popliteus tendons. On MR images of patients the lateral collateral ligament was depicted in all cases. The fabellofibular, arcuate, and popliteofibular ligaments were visualized in 33, 25, and 38% of patients, respectively. Magnetic resonance imaging allows a detailed appreciation of the posterolateral corner of the knee.     

MRI of knee ligament injury and reconstruction

Knee ligament instability may lead to meniscal and chondral damage, resulting in early osteoarthritis. Due to its superior soft tissue contrast and avoidance of harmful ionizing radiation, MRI has become the most important imaging modality for early recognition of structural defects of the knee joint. This review aims to the understanding of MRI appearances of knee ligament structures associated with knee instability, and to review the common patterns of altered knee mechanics that lead to ligament failure. Normal anatomy of the knee ligaments, pathologic conditions, and postsurgical appearances of the anterior cruciate ligament, posterior cruciate ligament, medial collateral ligament, and posterolateral corner are described. J. Magn. Reson. Imaging 2013;38:757–773 . © 2013 Wiley Periodicals, Inc .     

Biomechanics of the PCL and related structures: posterolateral,posteromedial and meniscofemoral ligaments

This paper reviews and updates our knowledge of the anatomy and biomechanics of the posterior cruciate ligament, and of the posterolateral, posteromedial and meniscofemoral ligaments of the knee. The posterior cruciate ligament is shown to have two functional fibre bundles that are tight at different angles of knee flexion. It is the primary restraint to tibial posterior draw at all angles of knee flexion apart from near full extension. In contrast, the posterolateral and posteromedial structures are shown to tighten as the knee extends, and to be well-aligned to resist tibial posterior draw. These structures also act as primary restraints against other tibial displacements. Tibial internal rotation is restrained by the medial and posteromedial structures, while tibial external rotation is restrained by the lateral and posterolateral structures. They are also the primary restraints against tibial abduction-adduction rotations. The meniscofemoral ligaments are shown, for the first time, to contribute significantly to resisting tibial posterior draw, and to have a strength of approximately 300 N. Taken together, this evidence shows how the posterolateral and posteromedial structures are responsible for posterior knee stability near extension, and this, along with the action of the meniscofemoral ligaments, may explain why an isolated rupture of the posterior cruciate ligament does not often lead to knee instability     

Comparison of 2 surgical techniques of posterolateral corner reconstruction of the knee

BACKGROUND: Various surgical techniques to treat posterolateral knee instability have been described. To date, the recommended treatment is an anatomical form of reconstruction, in which the 3 key structures of the posterolateral corner are addressed: the lateral collateral ligament, the popliteofibular ligament, and the popliteus tendon. HYPOTHESIS: Two methods of surgical reconstruction will restore posterolateral knee instability, in terms of static laxity as well as dynamic 6 degrees of freedom kinematics, to statistically significant levels compared with the intact state. STUDY DESIGN: Controlled laboratory study. METHODS: Two surgical techniques (A and B) were used to reconstruct the posterolateral structures in 10 cadaveric knees. Static tests were performed on the intact, sectioned, and reconstructed knees at 30 degrees and 90 degrees of flexion for anterior-posterior laxity and external rotational laxity, as well as at 0 degrees and 30 degrees of flexion for varus laxity; dynamic 6 degrees of freedom kinematic testing, through a path of motion from 90 degrees of flexion to full extension, was also performed. RESULTS: For the static varus tests, external rotation and varus laxity were significantly increased after the posterolateral structures were cut. Both reconstruction techniques restored external rotation and varus laxity to levels not significantly different from the intact state. For technique B, dynamic testing did not show any significant difference for all degrees of freedom kinematics compared with the intact state. However, for technique A, a significant internal tibial rotation was observed throughout the entire path of motion from 0 degrees to 90 degrees of knee flexion. CONCLUSIONS: Both surgical techniques for anatomical posterolateral corner reconstruction showed good results in the static laxity tests. The anatomical reconstruction of all structures, including the popliteus tendon, resulted in an abnormal internal tibial rotation during dynamic testing.     

Nonsurgical management of lateral side injuries of the knee

Non-surgical management of posterolateral corner (PLC) knee injuries is reserved for specific isolated mild to moderate injuries. There has been a relative scarcity of studies discussing non-surgical management existing secondary to the relative rarity of isolated PCL injuries. In these specific cases, a few studies have shown non-surgical management to result in satisfactory outcomes. This review of the literature outlines the outcomes and treatment options for posterolateral corner (PLC) knee injuries, which is based on the grade of the injury. However, no matter what the grade of injury, it is crucial to rule out other associated deficiencies before undertaking a nonoperative approach in the management of the posterolateral corner of the knee.     

Posteromedial corner injuries of the knee

Magnetic resonance imaging (MRI) depicts in exquisite detail the supporting structures of the posteromedial corner of the knee. This musculoligamentous unit plays a central role as a dynamic stabilizer of the knee joint and the recognition of injury to the posteromedial corner carries important implications in terms of management and prognosis, most particularly in the anterior cruciate ligament-deficient knee. This article provides a resumé of the functional anatomy of the posteromedial corner of the knee as seen with MRI and follows with a review of the MRI appearances of injury to the posteromedial corner.