Multiligament Knee Injuries

Introduction

Multiligament knee injuries (MLKIs) are a challenging clinical entity because of the increased number of ligaments involved, associated injuries, diagnosis, decision making about the optimal treatment and rehabilitation. These injuries are not as rare as previously reported; therefore a high level of suspicion and a thorough and systematic evaluation are mandatory to avoid missed or late diagnosis. Furthermore, some injuries may be misdiagnosed because about 50% of knee dislocations are reported to reduce before presentation. Historically, multiligament knee injuries were reported in association with knee dislocations ( Figs. 11.1 and 11.2 ); however, improved understanding of these injuries and better diagnostic tools have shown that not all MLKIs are caused by knee dislocations. True knee dislocations are rare and are associated with a higher risk of neurovascular injuries, ^, which can further complicate the injury and affect the prognosis. ^, It is important to diagnose and treat all injured structures because failure to address all injured structures can compromise knee function, leading to ligament reconstruction failure and poor outcomes.

Epidemiology and Injury Patterns

Previous studies reported that multiligament knee injuries caused by knee dislocations accounted for about 0.02% to 0.2% of all orthopaedic injuries. In a study based on registry data, Arom et al. estimated that the incidence of MLKI may be as high as 0.072 per 100 patient years.

Historically, knee dislocations have been associated with high-energy trauma such as motor vehicle accidents, falls from heights and farm or industry injuries. In the 19th and early 20th centuries the mechanisms of injury reported in the literature usually included more dramatic mechanisms such as a cart and horse falling on its owner, a man on horseback whose leg was pinned between a rail and the horse from which he was being thrown and, less often, some less dramatic injury mechanisms such as falls. With the advent of motorised vehicles, industrialisation and sports participation, the mechanisms of injury have changed.

Some studies have reported that 44% to 47% of MLKIs in their series were caused by sporting injuries. ^, With increasing sports participation, it is important to be aware of the possibility of complex knee injuries, despite an apparent low-energy mechanism, because these injuries can have devastating consequences if not properly diagnosed and managed. Furthermore, with the growing global burden of obesity, it is important to be aware of ultra-low-velocity knee dislocations and MLKI in obese individuals. Morbidly obese patients who sustain ultra-low-velocity MLKI have a high risk of neurovascular injuries and postoperative complications. The injury mechanism will differ depending on the clinical setting (trauma centre versus elective surgery centre), location (city, populations, country) and activities that are common in that area.

The medial side is the most commonly injured side of the knee, and up to 78% of high-grade (grade III) MCL injuries have an associated lesion, especially cruciate ligament and meniscus injuries. ^, Geeslin et al. reported that only 28% of posterolateral corner (PLC) knee injuries were isolated injuries, suggesting that most PLC injuries are combined ligament injuries or MLKI. Moatshe et al. reported that medial and lateral side injuries in knee dislocations (KDs) accounted for 52% and 28%, respectively, whereas Becker et al. reported a higher incidence of lateral injuries (knee dislocation grade III lateral (KDIII-L)), accounting for 43% of knee dislocations in a level 1 trauma centre.

Concomitant meniscal and cartilage injuries are common in multiligament injuries. Moatshe et al. reported that the incidence of meniscal injury in conjunction with multiligament knee injury was 37.3%, whereas the incidence of concomitant cartilage injury was 28.3%. Krych et al. reviewed a series of 122 knees and found that meniscal or chondral injury was present in 76% of cases. Richter et al. found that meniscal injury was only present in 15% of cases of multiligament knee injury, suggesting a lower prevalence. In a study on 194 sports-related MLKIs, LaPrade et al. found that 30% of the patients had chondral injuries and 55% had meniscal injuries. There has been increasing focus on meniscal root injuries; however, data on meniscal root injuries in the setting of MLKI are still lacking.

Diagnosis