Review articlePosterolateral corner injuries: Epidemiology, anatomy, biomechanics and diagnosis
Section snippets
Epidemiology
The prevalence of PLC injuries is difficult to quantify, partly due to difficulty in diagnosis. An MRI based prospective study [18], analysed patients presenting acutely with knee haemarthrosis following injury. Ligament injuries [4], [18] occurred in 187 (56%) of 331 patients. Of these 187 patients, 126 (67%) had isolated ligament injuries and 61 (33%) had combined multiple ligament injuries. Of the 187 patients, 4 (2.1%) had isolated PLC tears. The overall prevalence of posterolateral knee
Mechanism of injury
Isolated rupture of the PLC can be induced in the laboratory by a direct impact onto the proximal anteromedial tibia, causing combined hyperextension and varus [20]. Clinically, PLC injuries can be due to contact and non-contact hyperextension injury, non-contact varus injury or coupled hyperextension and external rotation [ER] [6], [7]. The PLC can be injured in complete knee dislocations [21], often in combination with other ligament injuries [19]. The PLC was injured in over 50% of PCL
Anatomy
Understanding of PLC anatomy has been hampered by its complexity and variability [20]. A three layered description (Illustration 1, Illustration 2 [78]) of the soft tissue structures on the lateral aspect of the knee has been proposed [23].
LCL
The mean length of the LCL has been reported as 70mm [10] and 59.2mm [33]. LCL strength has been measured in vitro at 750N [10] and 309N [33], with the lower reported strength due perhaps to the higher age of specimens tested. The reported [10] cross-sectional area of the LCL is 7.2 mm2.
The LCL is the primary restraint to varus of the knee [7], [8], [20]. Sectioning the LCL increased varus angulation significantly at low flexion angles, compared to intact knees [7], [8], [20]. Measurement of
History
Early diagnosis can mean the PLC can be repaired (or primarily reconstructed) with better prognosis, compared to reconstruction in chronic cases [14], [15], [16]. PLC injuries are often combined with injuries to other ligaments, particularly the PCL [1], [6], [7]. The ‘dashboard’ injury which occurs in car crashes is a classic example of this, when the impact onto the flexed knee displaces the tibia posteriorly. In multiligament injuries, the possibility of knee dislocation increases. This can
Roentgenograms
Plain Roentgenograms can occasionally aid the diagnosis of posterolateral corner injuries, and can also rule out other injuries. Possible Roentgenograms include the standard anteroposterior (AP) and lateral views and AP long-leg weight-bearing views. In patients with PLC injuries, as with most ligamentous injuries of the knee, plain radiographs are often normal.
Magnetic resonance imaging (MRI)
Magnetic resonance imaging (MRI) is the imaging modality of choice in knee ligament injuries. Yu et al. [74] developed thin-slice coronal oblique MRI sequences through the fibular head to supplement their standard MRI knee protocols to aid PLC injury diagnosis. This was developed from cadaveric studies. However their clinical MRI findings could not be validated operatively. LaPrade et al. [5] prospectively analysed 20 knees with PLC injuries using MRI. These results were then verified at
Summary
The anatomy and biomechanics of the posterolateral aspect of the knee are complex. Injuries to the PLC often go undiagnosed. They are usually accompanied by ACL or PCL injuries and are often treated only as isolated cruciate injuries. This leads to late presentations and the need for reconstruction, as opposed to early diagnosis and repair or primary reconstruction with better prognosis. Many diagnostic tests are described, but confusion surrounds their significance and purpose. A sound
Conflict of interest
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References (75)
- et al.
Practical management of posterolateral instability of the knee
Arthroscopy
(2002) Clinical evaluation of posterior cruciate ligament and posterolateral corner insufficiency
Oper Tech Sports Med
(2001)- et al.
Diagnosis and treatment of posterolateral knee injuries
Clin Orthop Rel Res
(2002) Posterior cruciate ligament injuries in trauma patients
Arthroscopy
(1993)- et al.
Biomechanics of the PCL and related structures:posterolateral, posteromedial and meniscofemoral ligaments
Knee Surg Sports Traumatol Arthrosc
(2003) - et al.
Functional anatomy of the Achilles tendon
Knee Surg Sports Traumatol Arthrosc
(2010) - et al.
The ligamentous structures of the posterolateral aspect of the knee
Bull Hosp Jt Dis Orthop Inst
(1990) - et al.
Effect of tibial positioning on the diagnosis of posterolateral rotatory instability in the posterior cruciate ligament-deficient knee
Br J Sports Med
(2007) - et al.
The role of the medial collateral ligament and posteromedial capsule in controlling knee laxity
Am J Sports Med
(2006) - et al.
Chronic posterolateral rotatory instability of the knee
J Bone Joint Surg Am
(1985)
Classification of knee ligament instabilities: I. The medial compartment and cruciate ligaments
J Bone Joint Surg Am
Ligamentous and capsular restraints preventing straight medial and lateral laxity in intact human cadaver knees
J Bone Joint Surg Am
The MRI appearance of individual structures of the posterolateral knee: a prospective study of normal and surgically verified grade 3 injuries
Am J Sports Med
Acute posterolateral instability of the knee
Am J Sports Med
Acute posterolateral rotatory instability of the knee
J Bone Joint Surg Am
Injuries to the posterolateral aspect of the knee: association of the injuries with clinical instability
Am J Sports Med
The popliteus tendon and it’s fascicles at the popliteus hiatus: gross anatomy and functional arthroscopic evaluation with and without anterior cruciate ligament deficiency
Arthroscopy
The posterolateral aspect of the knee: anatomy and surgical approach
Am J Sports Med
The popliteofibular ligament. Rediscovery of a key element in posterolateral instability
Am J Sports Med
On the cause of the anterolateral instability of the knee joint. A study on 20 cadaver knee joints with special regard to the tractus iliotibialis (author's transl) (article in German)
Arch Orthop Trauma Surg
The posterior cruciate ligament injured knee: principles of evaluation and treatment
Instr Course Lect
Anatomy, biomechanics and physical findings in posterolateral knee instability
Clin Sports Med
Combined PCL and PLC reconstruction in chronic posterolateral instability
Knee Surg Sports Traumatol Arthrosc
A prospective magnetic resonance imaging study of the incidence of posterolateral and multiple ligament injuries in acute knee injuries presenting with a hemarthrosis
Arthroscopy
Injuries of the posterolateral corner of the knee
J Bone Joint Surg Am
Epidemiology of posterior cruciate ligament injuries
Arch Orthop Trauma Surg
The structure of the posterolateral aspect of the knee
J Bone Joint Surg Am
The iliotibial tract: clinical and morphological significance
J Bone Joint Surg Am
Iliotibial band tension reduces patellar lateral stability
J Orthop Res
The anatomy of the iliopatellar band iliotibial tract
Am J Sports Med
Anatomy of the lateral retinaculum of the knee
J Bone Joint Surg Br
Anatomy of the knee joint lateral retinaculum
Clin Orthop Relat Res
Functional anatomy of the posterolateral structures of the knee
Arthroscopy
The role of the popliteofibular ligament in stability of the human knee: a biomechanical study
Am J Sports Med
Anatomic and biomechanical study of the lateral collateral and popliteofibular ligaments
Am J Sports Med
Proximal tibiofibular joint: a radiographic and computed tomographic study
Tohoku J Exp Med
The role of the cruciate and posterolateral ligaments in stability of the knee. A biomechanical study
Am J Sports Med
Loading of the two bundles of the human posterior cruciate
J Biomech
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Role of the proximal tibiofibular joint on the biomechanics of the knee joint: A three-dimensional finite element analysis
2022, InjuryCitation Excerpt :Ren D et al. [23–24,28] have researched the biomechanical roles of ligaments in maintaining knee stability, by using finite element analysis. The main structures that provide stability to the lateral aspect of the knee are the lateral collateral ligament, popliteofibular ligament and popliteus tendon [26,29,33]. However, the role of these ligaments is closely related to the stability of the PTFJ.
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2022, Operative Techniques in Sports MedicineCitation Excerpt :A positive reverse pivot shift may be present in 35% of uninjured knees with physiologic hyperlaxity and therefore, the contralateral knee should always be examined for comparison.32 Additionally, the classic pivot shift test for ACL injury may be positive in the setting of lateral sided ligament injury, as lateral, and posterolateral injuries occur rarely in isolation.33 In order to perform the pivot shift, the knee is held in a position of full extension with valgus, and internal rotation force applied by the examiner.
Surgical Principles for Lateral Collateral and Posterolateral Knee Injuries
2022, Operative Techniques in Sports MedicineCitation Excerpt :The 3 primary static stabilizers include the fibular collateral ligament (FCL), popliteus tendon (PLT), and popliteofibular ligament (PFL).2,3 Injury to the PLC occurs in 16% of all knee ligament injuries and 9.1% of all acute knee injuries with a hemarthrosis.4 The mechanism of injury to the PLC includes contact and non–contact hyperextension injuries, complete knee dislocations, non–contact varus injury, or coupled hyperextension, and external rotation.5
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2019, KneeCitation Excerpt :Posterolateral complex (PLC) injuries comprise approximately 16% of all knee ligament injuries, and most of these injuries affect the central pivot ligaments. Isolated injuries occur in two percent of all cases [1]. For grade I injuries or injuries without instability, conservative treatment progresses with satisfactory results [2].