Elsevier

Injury

Volume 49, Issue 6, June 2018, Pages 1024-1031
Injury

Review article
Posterolateral corner injuries: Epidemiology, anatomy, biomechanics and diagnosis

https://doi.org/10.1016/j.injury.2017.10.008Get rights and content

Abstract

Increased internal and external rotational laxity of the knee may result from a wide range of pathologies in or around the knee. However, the principal cause of increased external rotational laxity is damage to the posterolateral corner (PLC). The aim of the review is to discuss the epidemiology, anatomy, biomechanics and diagnosis of PLC injuries.

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

None

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      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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