Vascular lesions associated with bicruciate and knee dislocation ligamentous injury

No effect of dislocation status at arrival in emergency department on outcome of knee joint dislocations

PURPOSE

Knee dislocation is a rare but severe injury of the lower extremities. The aim of this study was to report on the epidemiology, diagnostics and treatment of such injuries and to identify negative predictors of clinical outcomes.

METHODS

This retrospective analysis included all knee dislocations treated at a Level I Trauma Centre in Germany between 2009 and 2021. Medical records were categorised, collected and analysed in a standardised manner. A follow-up visit 1 year after the injury focused on limitations in knee mobility.

RESULTS

A total of 120 knee dislocations were included in the study. 29.3% of patients presented to the emergency department with a dislocated joint, and 17.5% (n = 21) had a neurovascular lesion. At follow-up 12 months after the injury, 65.8% of the patients reported limitations in the range of motion, and 11.7% (n = 14) reported severe limitations in daily activities. Site infections due to surgery occurred in 3.3% of patients. Increased body weight (r = 0.294; p < 0.001 and r = 0.259; p = 0.004), an increased body mass index above 25 kg/m2 (body mass index, r = 0.296; p < 0.001 and r = 0.264; p = 0.004) and deficits in peripheral perfusion as well as sensory and motor function (r = 0.231; p = 0.040 and r = -0.192; p = 0.036) were found to be negative predictive factors for clinical outcome. For posttraumatic neurovascular injury, lack of peripheral perfusion, insufficient sensory and motor function (r = -0.683; p < 0.0001), as well as a higher Schenck grade (r = 0.320; p = 0.037), were identified as independent risk factors. The status of dislocation at the site of the accident and on arrival at the emergency department had no impact on the outcome or neurovascular injury.

CONCLUSION

Knee dislocation is a rare injury with a high rate of severe complications such as neurovascular lesions. In particular, the initial status of neurovascular structures and injury classification showed a relevant negative correlation with the posttraumatic status of nerves and vessels. In particular, patients with these characteristics need close monitoring to prevent negative long-term consequences.

LEVEL OF EVIDENCE

Level III.

[MCL tear with intra-articular dislocation]

A 48-year-old male patient presented with inner skin retraction after a sports accident involving the knee. In a multi-ligament injury it must be assumed that knee dislocation has occurred. Inner skin retraction after knee distortion can result from an intra-articular dislocation of the ruptured medial collateral ligament. Prompt reduction and exclusion of concomitant neurovascular injuries is thus obligatory. After surgical reconstruction of the medial collateral ligament, instability was no longer apparent 3 months postoperatively.

A systematic review on management and outcome of irreducible knee dislocations

BACKGROUND

Irreducible knee dislocations (IKD) are rare and can often be missed or misdiagnosed. The incidence of knee dislocation is quoted between 0.01% and 0.2% of all orthopaedic injuries, with up to 4% of these dislocations sub-classified as irreducible. The primary aim of this systematic review was to analyse cases of IKD described in the literature, with a secondary aim of producing a streamlined approach for managing these patients.

PATIENTS AND METHODS

A systematic review of the literature was conducted on 1st September 2021 in accordance with the PRISMA guidelines using the online databases Medline and EMBASE. The review was registered prospectively in the PROSPERO database. Case reports or clinical studies or reporting on IKD were included. The studies were appraised using the Methodological Index for Non-Randomized Studies (MINORS) tool and Newcastle-Ottawa quality assessment scale.

RESULTS

The search strategy identified 60 studies eligible for inclusion, giving a total of 114 cases of IKD. Posterolateral dislocation was most common, seen in 85% of cases. The dimple sign was present in 70%. All cases required surgical intervention to achieve joint reduction. The most commonly involved structure blocking reduction was the medial collateral ligament (MCL)±medial structures, seen in 52.4%. MCL reconstruction or repair was carried out in 32.3% cases. The overall incidence of neurovascular injury was 9% and the overall complication rate was 14.4%.

CONCLUSION

Based on the findings of this SR we conclude that: the most common type of IKDs are PL dislocations, and the MCL, medial retinaculum and capsule and vastus medialis oblique form the most common structures involved in block to reduction and often will require open reduction and repair in acute setting if arthroscopic reduction fails. The most common pattern of injury to ligament is likely to be ACL, PCL, MCL±other structures but the MCL will be the most commonly repaired ligament. The dimple sign is often present and is highly pathognomonic of IKD. The incidence of neurovascular injury is uncommon. The most common post-operative complications likely to be encountered is medial skin necrosis and postoperative knee stiffness. Therefore, patients should be mobilised as early as possible with ROM in hinge brace.

LEVEL OF EVIDENCE

IV.

Guidelines for the acute care of severe limb trauma patients

GOAL

To provide healthcare professionals with comprehensive multidisciplinary expert recommendations for the acute care of severe limb trauma patients, both during the prehospital phase and after admission to a Trauma Centre.

DESIGN

A consensus committee of 21 experts was formed. A formal conflict-of-interest (COI) policy was developed at the onset of the process and enforced throughout. The entire guidelines process was conducted independently of any industrial funding (i.e., pharmaceutical, medical devices). The authors were advised to follow the rules of the Grading of Recommendations Assessment, Development and Evaluation (GRADE®) system to guide assessment of the quality of evidence. The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasised. Few recommendations remained non-graded.

METHODS

The committee addressed eleven questions relevant to the patient suffering severe limb trauma: 1) What are the key findings derived from medical history and clinical examination which lead to the patient's prompt referral to a Level 1 or Level 2 Trauma Centre? 2) What are the medical devices that must be implemented in the prehospital setting to reduce blood loss? 3) Which are the clinical findings prompting the performance of injected X-ray examinations? 4) What are the ideal timing and modalities for performing fracture fixation? 5) What are the clinical and operative findings which steer the surgical approach in case of vascular compromise and/or major musculoskeletal attrition? 6) How to best prevent infection? 7) How to best prevent thromboembolic complications? 8) What is the best strategy to precociously detect and treat limb compartment syndrome? 9) How to best and precociously detect post-traumatic rhabdomyolysis and prevent rhabdomyolysis-induced acute kidney injury? 10) What is the best strategy to reduce the incidence of fat emboli syndrome and post-traumatic systemic inflammatory response? 11) What is the best therapeutic strategy to treat acute trauma-induced pain? Every question was formulated in a PICO (Patient Intervention Comparison Outcome) format and the evidence profiles were produced. The literature review and recommendations were made according to the GRADE® methodology.

RESULTS

The experts' synthesis work and the application of the GRADE method resulted in 19 recommendations. Among the formalised recommendations, 4 had a high level of evidence (GRADE 1+/-) and 12 had a low level of evidence (GRADE 2+/-). For 3 recommendations, the GRADE method could not be applied, resulting in an expert advice. After two rounds of scoring and one amendment, strong agreement was reached on all the recommendations.

CONCLUSIONS

There was significant agreement among experts on strong recommendations to improve practices for severe limb trauma patients.

[Emergency treatment of dislocation of large joints]

Joint dislocations are always accompanied by rupture of the joint capsule. Depending on the forces exerted on the joint as well as individual bone quality, fractures (dislocation fractures) and injuries to ligaments occur. As blood vessels and nerves can also be damaged, reduction is an urgent measure. Only impaired peripheral perfusion, loss of motor function or sensation justify reduction without radiological documentation. As reduction can be a painful procedure, analgosedation is nearly always necessary. Evidence for superiority of individual maneuvers is weak. Reduction is followed by immobilization and documented by another control X‑ray. Follow-up treatment depends on concomitant injuries, age and individual demands on joint function. Even with correct follow-up treatment, deficits often persist. This article deals with the diagnostics and treatment of dislocations of the shoulder, elbow, hip, patella and knee.

Controversies in acute multiligamentary knee injuries (MLKI)

Multiligament injuries of the knee (MLKI), remain an infrequent pathology especially in developed countries compared to mono-ligament lesions. In Colombia, MLKI is frequent due to the high accident rate on motorcycles. In the city of Bogota alone, about 160 motorcycle accidents have been estimated daily, being one of the cities that proportionately use this means of transport less compared to small cities. The term MLKI, include all ruptures of two or more major ligaments and therefore it has a broad spectrum of clinical presentation which creates a great challenge for the orthopedists and the surgeons envolved in this topic. The literature is rich in studies level IV but very poor in level I and level II, which generates controversies and little consensus in the diagnosis and treatment of this pathology. However there has been a gradual and better understanding of all factors involved in the treatment of MLKI that has improved the functional results of these knees in our patients, in fact we currently are more precise to achieve accurate diagnosis, evolved from not surgical approach to operate most, applying new anatomical and biomechanical concepts, with specialized and skill surgical techniques with more stable and biocompatible fixation implants, which allow in most cases to initiate an early integral rehabilitation program. Nevertheless due to the complexity and severity of the lesions, in some patients the functional results are poor. The goal of this revision is to identify the most frequent controversies in the diagnosis and treatment of MLKI, defining which of them are agreed according to what is reported in the literature and share some concepts based from the experience of more than 25 years of the senior author (MM) in the management of these injuries. LEVEL OF EVIDENCE: V - Expert Opinion.

Which Risk Factors Predict Knee Ligament Injuries in Severely Injured Patients?-Results from an International Multicenter Analysis

Introduction: Ligament injuries around the knee joint and knee dislocations are rare but potentially complex injuries associated with high-energy trauma. Concomitant neurovascular injuries further affect their long-term clinical outcomes. In contrast to isolated ligamentous knee injuries, epidemiologic data and knowledge on predicting knee injuries in severely injured patients is still limited. Methods: The TraumaRegister DGU^® (TR-DGU) was queried (01/2009–12/2016). Inclusion criteria for selection from the database: maximum abbreviated injury severity ≥ 3 points (MAIS 3+). Participating countries: Germany, Austria, and Switzerland. The two main groups included a “control” and a “knee injury” group. The injury severity score (ISS) and new ISS (NISS) were used for injury severity classification, and the abbreviated injury scale (AIS) was used to classify the severity of the knee injury. Logistic regression analysis was performed to evaluate various risk factors for knee injuries. Results: The study cohort included 139,462 severely injured trauma patients. We identified 4411 individuals (3.2%) with a ligament injury around the knee joint (“knee injury” group) and 1153 patients with a knee dislocation (0.8%). The risk for associated injuries of the peroneal nerve and popliteal artery were significantly increased in dislocated knees when compared to controls (peroneal nerve from 0.4% to 6.7%, popliteal artery from 0.3% to 6.9%, respectively). Among the predictors for knee injuries were specific mechanisms of injury: e.g., pedestrian struck (Odds ratio [OR] 3.2, 95% confidence interval [CI]: 2.69–3.74 p ≤ 0.001), motorcycle (OR 3.0, 95% CI: 2.58–3.48, p ≤ 0.001), and motor vehicle accidents (OR 2.2, 95% CI: 1.86–2.51, p ≤ 0.001) and associated skeletal injuries, e.g., patella (OR 2.3, 95% CI: 1.99–2.62, p ≤ 0.001), tibia (OR 1.9, 95% CI: 1.75–2.05, p ≤ 0.001), and femur (OR 1.8, 95% CI: 1.64–1.89, p ≤ 0.001), but neither male sex nor general injury severity (ISS). Conclusion: Ligament injuries and knee dislocations are associated with high-risk mechanisms and concomitant skeletal injuries of the lower extremity, but are not predicted by general injury severity or sex. Despite comparable ISS, knee injuries prolong the hospital length of stay. Delayed or missed diagnosis of knee injuries can be prevented by comprehensive clinical evaluation after fracture fixation and a high index of suspicion is advised, especially in the presence of the above mentioned risk factors.

ACR Appropriateness Criteria® Acute Trauma to the Knee

Acute trauma to the knee is a common presentation seen in the emergency department. After a routine clinical examination, imaging is frequently performed to facilitate the diagnosis and almost always starts with radiographs. If clinically indicated, advanced cross-sectional imaging may then be performed for further evaluation. CT is often performed for preoperative planning of the complex tibial plateau and distal femur fractures. Currently, MRI is the study of choice for evaluation of bone marrow, internal derangements, and other soft-tissue injuries about the knee joint. In patients with knee dislocations, MR angiography may be performed simultaneously with MRI for evaluation of internal derangements and vascular injuries with less morbidity compared to conventional angiography. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Varus mechanism is associated with high incidence of popliteal artery lesions in multiligament knee injuries

PURPOSE

This study aims to identify multiple ligament knee injury patterns that possess a high-risk of vascular lesion.

METHODS

We retrospectively compared torn ligament patterns and the presence of vascular lesions confirmed by magnetic resonance imaging and computed tomography angiography from 122 consecutive patients with diagnoses of multiple ligament knee injury made at the emergency department between January 2012 and December 2017. Patients were not eligible if they had an ipsilateral lower extremity lesion (dislocations or fractures at another level), initial evaluation at another hospital, or follow-up for less than 12 months. The primary outcomes were the comparison between the imaging findings of torn structures patterns and the presence of a vascular lesion.

RESULTS

We identified 48 eligible patients (50 knees) with multiligamentary knee lesions, of whom eight had popliteal artery damage, yielding an incidence of 16%. Our clinical examination detected six of these patients that were classified, according to the Schenck system, as KD-IIIL (6 knees) and KD-IIIM (2 knees). The odds of having a popliteal artery injury is 4.69 to 1 with a KD-IIIL injury that with any other type of injury on that classification (95% CI 0.960-22.98).

CONCLUSIONS

This data suggests that varus forces causing enough energy to produce a KD-IIIL lesion possess a higher popliteal artery injury risk, making recommendable a thorough examination of the vascular integrity when diagnosing a KD-IIIL lesion.

Evaluation and Management of Knee Dislocation in the Emergency Department

BACKGROUND

Knee dislocations are a potentially limb-threatening injury, and it is essential that emergency medicine clinicians are aware of them.

OBJECTIVE

This article provides a review of the diagnosis and management of knee dislocation for the emergency provider.

DISCUSSION

Knee dislocations are uncommon injuries with the potential for significant morbidity. A thorough history and examination are important, because 50% of dislocations may have reduced before arrival to the emergency department. Knee dislocations should be quickly reduced in the emergency department setting. The presence of equal pulses does not exclude vascular injury, and all patients should undergo serial vascular examinations and evaluation with ankle-brachial indices. Those with abnormal ankle-brachial indices should receive computed tomographic angiography. Radiographs are important to identify any fractures, while magnetic resonance imaging may be deferred until after admission.

CONCLUSION

Knee dislocation is a potentially dangerous medical condition requiring rapid diagnosis and management. It is essential for emergency clinicians to know how to diagnose and treat this disorder.

Knee dislocation with popliteal artery disruption: A nationwide analysis from 2005 to 2013

Objective

Few have compared short-term outcomes following knee dislocations with or without concomitant popliteal artery disruption (PAD).

Methods

The Nationwide Inpatient Sample was used to identify 2175 patients admitted for knee dislocation from 2005 to 2013 (concomitant PAD: n = 210/9.7%; without: n = 1965/90.3%).

Results

Patients with PAD were younger, more often male, Black and Hispanic, and with Medicaid (all p ≤ 0.013). PADs were associated with 11.0-times higher odds of increased LOS (95%CI, 6.6-18.4) and 2.8-times higher odds of experiencing any complication (95%CI, 2.03-3.92). Female sex was a protective factor against increased LOS, (OR = 0.65; 95%CI, 0.48-0.88).

Conclusion

High suspicion index should be maintained for concomitant vascular injuries following knee dislocations.

Management of knee dislocation prior to ligament reconstruction: What is the current evidence? Update of a universal treatment algorithm

Traumatic knee dislocation is a rare but potentially limb-threatening injury. Thus proper initial diagnosis and treatment up to final ligament reconstruction are extremely important and a precondition to successful outcomes. Reports suggest that evidence-based systematic approaches lead to better results. Because of the complexity of this injury and the inhomogeneity of related literature, there are still various controversies and knowledge gaps regarding decision-making and step-sequencing in the treatment of acute multi-ligament knee injuries and knee dislocations. The use of ankle-brachial index, routine or selective angiography, braces, joint-spanning or dynamic external fixation, and the necessity of initial ligament re-fixation during acute surgery constitutes current topics of a scholarly debate. The aim of this article was to provide a comprehensive literature review bringing light into some important aspects about the initial treatment of knee dislocation (vascular injury, neural injury, immobilization techniques) and finally develop an accurate data-based universal algorithm, enabling attending physicians to become more acquainted with the management of acute knee dislocation.

Review article: Best practice management of common knee injuries in the emergency department (part 3 of the musculoskeletal injuries rapid review series)

Knee injuries are a common presentation to the ED and are often difficult to assess and definitively diagnose due to the patient's acute pain, effusion and guarding. The quality of ED care provided to patients with fractures or soft tissue injuries of the knee is critical to ensure the best possible outcomes for the patient. This rapid review investigated best practice for the assessment and management of common knee injuries in the ED. Databases were searched in 2017, including PubMed, CINAHL, EMBASE, TRIP and the grey literature, including relevant organisational websites. Primary studies, systematic reviews and guidelines were considered for inclusion. English-language articles published in the past 12 years that addressed the acute assessment, management, follow-up plan or prognosis were included. Data extraction of included articles was conducted, followed by quality appraisal to rate the level of evidence where possible. The search revealed 2250 articles, of which 54 were included in the review (n = 8 primary articles, n = 28 systematic reviews, n = 18 guidelines). This rapid review provides clinicians managing fractures and soft tissue injuries of the knee in the ED, a summary of the best available evidence to enhance the quality of care for optimal patient outcomes. There is consistent evidence to support undertaking a thorough history and physical examination, including the application of special tests and clinical decision rules for imaging. In the undifferentiated knee injury, expedited follow up and further imaging is recommended to improve patient outcomes and cost-effectiveness.

Knee Dislocations in Sports Injuries

Knee dislocations are devastating when they occur on the athletic field or secondary to motor sports. The complexity of presentation and spectrum of treatment options makes these injuries unique and extremely challenging to even the most experienced knee surgeons. An astute appreciation of the treatment algorithm is essential to plan individualized management since no two complex knee dislocations are ever the same. Moreover, attention to detail and finesse of surgical technique are required to obtain a good functional result and ensure return to play. Over the past 10 years, our service has treated 43 competitive sportsmen with knee dislocations, and this experience forms the basis for this narrative review.

Knee dislocation and vascular injury: 4 year experience at a UK Major Trauma Centre and vascular hub

INTRODUCTION

Knee dislocation is a rare but potentially devastating injury. Quoted rates of associated vascular compromise vary dramatically between 3.3% and 64%, and the best approach to investigate and diagnose such an injury remains controversial. We aim to evaluate our own 4-year experience of knee dislocation and vascular injury as a UK Major Trauma Centre and vascular hub.

METHODS

Knee dislocation was defined as disruption of at least two major stabilising ligaments of the knee and gross instability requiring an operation. Patients were identified from the Department of Trauma and Orthopaedics patient database across a 4 year period from 2010 to 2014. Electronic patient records, imaging and hard notes were retrieved and reviewed retrospectively and relevant information recorded.

RESULTS

Twenty-five cases of knee dislocation were identified. Male to female ratio was 11.5:1 with a mean age of 33 years (range 17-71). One patient had a vascular injury which ultimately required a femoro-popliteal bypass graft. Twenty-four patients had documented examination findings pertaining to the vascular status of the limb. Seventeen patients had specific reference to the presence or absence of pedal pulses. The remaining seven cases were documented as either "warm well perfused" or "neurovascularly in-tact". Nine patients were discharged directly from the emergency department with outpatient follow up. All admitted cases had documented vascular examination findings the following day. Two patients had additional adjunctive non-invasive investigations. No patients were examined with duplex ultrasound, although two patients had pulses confirmed with hand-held doppler ultrasound. Three patients had an angiogram. Four cases have a documented discussion with or review from a vascular surgeon.

DISCUSSION AND CONCLUSIONS

Our rates of vascular injury are in line with the most recent and largest study to date. Non-invasive investigation and selective angiography has been safe in identifying significant vascular compromise, however, there is inconsistency in management pathways, and too much reassurance attributed to the presence of pedal pulses on initial examination. Safety and consistency could be improved with the introduction of a formalised evidence-based protocol for the initial evaluation of knee dislocation and vascular injury.

A Two-stage procedure for the treatment of a neglected posterolateral knee dislocation: Gradual reduction with an Ilizarov external fixator followed by arthroscopic anterior and posterior cruciate ligament reconstruction

BACKGROUND

Neglected knee dislocations are extremely uncommon and their management cannot be evidence-based since only a few case reports have been published describing different treatment methods. We present the case of a young man with a neglected posterolateral knee dislocation and a concomitant sciatic nerve injury.

METHODS

A two-stage treatment strategy with gradual reduction using the Ilizarov technique and subsequent arthroscopic anterior and posterior cruciate ligament reconstruction was followed.

RESULTS

The two-stage treatment approach led to a satisfactory clinical outcome. At the latest follow-up evaluation the patient was fully ambulatory and the knee was painless with no anteroposterior instability.

CONCLUSIONS

In neglected knee dislocations treatment optios are guided by the severity of the concomitant injuries and the status of articulating surfaces. Gradual reduction with the Ilizarov technique and subsequent arthroscopic ligamentous reconstruction is a reliable alternative to open surgical procedures.

Popliteal artery injury associated with blunt trauma to the knee without fracture or dislocation

Popliteal artery injuries are frequently seen with fractures, dislocations, or penetrating injuries. Concern about arterial injury and early recognition of the possibility of arterial injury is crucial for the salvage of the extremity. This article provides an outline of the diagnostic challenges related to these rare vascular injuries and emphasizes the necessity for a high level of suspicion, even in the absence of a significant penetrating injury, knee dislocation, fracture, or high-velocity trauma mechanism. The importance of a detailed vascular examination of a blunt trauma patient is emphasized.

Pediatric Knee Dislocations and Physeal Fractures About the Knee

Given the high incidence of vascular and neurologic injury associated with pediatric knee dislocations and displaced physeal injuries about the knee, a thorough understanding of the clinical and radiographic signs associated with these injuries, relevant anatomy, workup, reduction techniques, and surgical management is crucial. A higher incidence of these injuries in children is anticipated because of increased participation in high-energy activities that result in contact or collision during sports or recreation. Complications, such as vascular and nerve injuries and compartment syndrome, can be diagnosed early in the workup to prevent catastrophic outcomes. The clinical examination should include evaluation of the motor and sensory status of the limb, palpation of pulses, and measurement of ankle brachial indices. Radiographic examination should include plain radiography and supplemental advanced imaging, if indicated. Vascular imaging or expert consultation should be considered when the pulse or ankle brachial index is abnormal on clinical examination. Selection of nonsurgical or surgical treatment depends on the fracture pattern and stability.

Radiological assessment of irreducible posterolateral knee subluxation after dislocation due to interposition of the vastus medialis: a case report

Knee dislocation is a serious and relatively uncommon traumatism that every emergency room is supposed to diagnose and treat rapidly. Most of the time these dislocations reduce spontaneously or with closed reduction. If a subluxation persists, an incarceration of soft tissue in the joint must be suspected. Irreducible knee subluxations after dislocation are rare entities better described in the orthopaedic than in the radiological literature. However, the initial radiological assessment is an important tool to obtain the correct diagnosis, to detect neurovascular complications, and to plan the most suitable treatment. In cases of delayed diagnosis, the functional prognosis of the joint and even the limb may be seriously compromised primarily because of vascular lesions. Thereby, vascular imaging is essential in cases of dislocation of the knee, and we will discuss the role of angiography and the more recent use of computed tomography angiography or magnetic resonance angiography. Our patient presented with an irreducible knee subluxation due to interposition of the vastus medialis, and we will review the classical clinical presentation and 'do not miss' imaging findings on conventional radiography, computed tomography angiography, and magnetic resonance imaging. Finally, we will also report the classical imaging pathway indicated in knee dislocation, with a special emphasis on the irreducible form.

The changing demographics of knee dislocation: a retrospective database review

BACKGROUND

Knee dislocations are uncommon but devastating orthopaedic injuries. Little is known about their frequency and the types of patients who are affected.

QUESTIONS/PURPOSES

Using a large national insurance database, we determined (1) the incidence of knee dislocation in patients with orthopaedic injuries and examined the incidence as a function of (2) year of diagnosis, (3) dislocation type (open versus closed, direction), and (4) patient demographic factors (sex, age).

METHODS

We searched the PearlDiver database, a national database of private insurance records consisting of 11 million patients with orthopaedic diagnoses, using diagnosis (ICD-9-CM) codes for knee dislocation between the years 2004 and 2009. The PearlDiver database does not include Medicare, Medicaid, or uninsured patients. Patients were stratified by age, sex, and year of diagnosis. Incidence was defined as the number of dislocation events per 100 patient-years.

RESULTS

We identified 8050 dislocations, representing an incidence of 0.072 events per 100 patient-years between 2004 and 2009. Annual dislocation incidence did not increase during the 6-year study period. Of the 8050 dislocations, 1333 (17%) were open and 6717 (83%) were closed, representing an incidence of 0.060 per 100 for closed dislocations and 0.012 per 100 for open dislocations. The most common direction of dislocation was unspecified or other (65%), followed by anterior (13%), lateral (11%), posterior (6%), and medial (5%). Of the patients sustaining dislocations, 4172 (52%) were female and 3878 (48%) were male. Males displayed an increased risk of knee dislocation compared to females (odds ratio = 1.09). The mean patient age was 35 years, and patient age was inversely correlated to the incidence of knee dislocation (10-year odds ratio = 0.77).

CONCLUSIONS

Our data suggest that knee dislocation might represent a significantly larger burden among orthopaedic injuries than previously thought. The finding that males and females have a nearly equal risk of knee dislocation enhances the diagnosing physician's clinical suspicion of this injury. Future large prospective studies analyzing the various causes of knee dislocation could provide insight into the changing demographics of this injury.

LEVEL OF EVIDENCE

Level IV, prognostic study. See Instructions for Authors for a complete description of levels of evidence.

Vascular and nerve injury after knee dislocation: a systematic review

BACKGROUND

Vascular injury is a devastating complication of acute knee dislocation. However, there are wide discrepancies in the reported frequency of vascular injury after knee dislocations, as well as important differences among approaches for diagnosis of this potentially limb-threatening problem.

QUESTIONS/PURPOSES

We determined (1) the frequency of vascular and neurologic injury after knee dislocation and whether it varied by the type of knee dislocation, (2) the frequency with which surgical intervention was performed for vascular injury in this setting, and (3) the frequency with which each imaging modality was used to detect vascular injury.

METHODS

We searched the MEDLINE(®) literature database for studies in English that examined the clinical sequelae and diagnostic evaluation after knee dislocation. Vascular and nerve injury incidence after knee dislocation, surgical repair rate within vascular injury, and amputation rate after vascular injury were used to perform a meta-analysis. Other measures such as diagnostic modality used and the vessel injured after knee dislocation were also evaluated.

RESULTS

We identified 862 patients with knee dislocations, of whom 171 sustained vascular injury, yielding a weighted frequency of 18%. The frequency of nerve injuries after knee dislocation was 25% (75 of 272). We found that 80% (134 of 160) of vascular injuries underwent repair, and 12% (22 of 134) of vascular injuries resulted in amputation. The Schenck and Kennedy knee dislocation classifications with the highest vascular injury prevalence were observed in knees that involved the ACL, PCL, and medial collateral liagment (KDIIIL) (32%) and posterior dislocation (25%), respectively. Selective angiography was the most frequently used diagnostic modality (61%, 14 of 23), followed by nonselective angiography and duplex ultrasonography (22%, five of 23), ankle-brachial index (17%, four of 23), and MR angiography (9%, two of 23).

CONCLUSIONS

This review enhances our understanding of the frequency of vascular injury and repair, amputation, and nerve injuries after knee dislocation. It also illustrates the lack of consensus among practitioners regarding the diagnostic and treatment algorithm for vascular injury. After pooling existing data on this topic, no outcomes-driven conclusions could be drawn regarding the ideal diagnostic modality or indications for surgical repair. In light of these findings and the morbidity associated with a missed diagnosis, clinicians should err on the side of caution in ruling out arterial injury.

Current concepts in acute knee dislocation: the missed diagnosis?

Traumatic knee dislocation is a serious and potentially limb threatening injury that can be easily missed if meticulous history and examination have not been employed. Neurovascular injuries are common in this condition, and due diligence should be given to their thorough evaluation at time of secondary survey so as to avoid complications such as ischaemia, compartment syndrome and eventual amputation. There is growing evidence in the literature that morbid obesity is associated with low energy knee dislocation, therefore this should be considered when assessing this cohort of patients presenting with an acute knee injury. Early operative intervention especially with multi ligaments involvement is the preferable strategy in the management of this acute injury. Controversy exists whether to reconstruct or repair damaged structures, and whether to adopt a one stage or two stage reconstruction of the cruciate ligaments. Early rehabilitation is important and essential to achieve satisfactory outcomes. This article is an evidence-based overview of this rare but devastating injury.

Acute knee dislocation

Traumatic knee dislocations are relatively rare yet serious injuries. They remain under diagnosed injuries in view of the frequency with which they can present having spontaneously reduced. Diagnosis requires a high index of clinical suspicion on presentation of all knee injuries. Careful, repeated and vigilant monitoring for neurovascular compromise following diagnosis, appropriate investigations and early involvement of surgeons with a specialist interest in knee ligament injury are important factors in managing these injuries. The prognosis has improved in recent years following establishment of some consensus on the evaluation, investigation, management and rehabilitation of these injuries and this article presents an evidence based review of these principles.

Popliteal lesion due to traction during unicompartmental knee revision surgery

Popliteal artery injury is a rare but known complication in knee surgery. Only one article in current literature reports that the risk increases during revision knee surgery. A new case is described in which an injury to the popliteal artery occurred during lateral unicompartmental to total knee arthroplasty revision surgery. This vascular injury occurred 5-10 cm below the tibial resection level in a healthy patient with a history of cruris fracture with plate osteosynthesis and lateral unicompartmental knee arthroplasty. This paper stresses the importance of being aware that trauma and surgery can create fibrosis in which the popliteal artery can get fixated, thus reducing the scope for safe manipulation of the knee during secondary surgery.

Radiologic review of knee dislocation: from diagnosis to repair

OBJECTIVE

This imaging-based article systematically reviews traumatic knee dislocations. After completion, the reader should be familiar with the definition, epidemiology, cause, and classification schemes associated with these injuries, as well as the importance of timely diagnostic imaging and an accurate, detailed description of findings, particularly as it relates to MRI interpretation. Finally, information our orthopedic surgical colleagues consider critical for the preoperative planning and reconstruction of the multiple ligament knee injury will be discussed.

CONCLUSION

Although uncommon, traumatic knee dislocations are an important potentially limb-threatening injury, which if not emergently recognized and appropriately managed, can result in significant patient morbidity, joint dysfunction, chronic pain, and long-term disability. A radiologist familiar with the imaging appearance and potential neurovascular complications associated with these injuries can play an integral role in the multidisciplinary team that manages this increasingly recognized clinical entity.

Relevancy and reproducibility of magnetic resonance imaging (MRI) interpretation in multiple-ligament injuries and dislocations of the knee

INTRODUCTION

After multiple-ligament injuries and dislocations of the knee, clinical assessment of the soft tissues is difficult and MRI is generally performed.

HYPOTHESIS

MRI is a reliable examination, providing a precise and reproducible assessment of soft-tissue lesions after multiple-ligament injuries or dislocations of the knee.

MATERIALS AND METHODS

Forty patients presenting multiple-ligament lesions of the knee were included in this multicenter prospective study. All had an MRI of the knee in the 48 h following their accident. Thirty-four patients were treated surgically. A 17-item standardized interpretation guide was created. Intraobserver reproducibility was assessed by comparing the interpretations of five surgeons at two different times 3 weeks apart. Interobserver reproducibility was evaluated by comparing the results of the interpretations of 40 MRIs performed by three pairs of surgeons. The relevance of the MRI interpretations was determined by comparing the results of the surgeons to those of a radiologist and with the data from the surgical reports.

RESULTS

The overall intraobserver and interobserver agreement was low. Comparing the surgeon's results with the radiologist's results and the surgical data, the agreement was low.

DISCUSSION

After multiple-ligament injuries and dislocations of the knee, a precise diagnosis is necessary. This study provides an isolated demonstration of the lack of precision and reproducibility of MRI interpretations for the diagnosis of the lesion's topography. MRI should be integrated into a complete assessment with a precise clinical exam and stress X-rays.

LEVEL OF EVIDENCE

Level IV, prospective case-control study.

[Vascular injuries associated with dislocation of the knee: diagnosis protocol]

INTRODUCTION

Knee dislocation is an unusual condition, and can have catastrophic consequences, such as vascular and neurological complications, in addition to the ligament injuries.

OBJECTIVE

The aim of this study is to analyse the effectiveness of a protocol of early diagnosis of vascular injuries associated with knee dislocations.

MATERIALS AND METHODS

A retrospective study was conducted which included acute knee dislocations treated in our institution, with a minimum of 12 months follow-up, between 1999-2010. A diagnostic protocol based on physical examination and ankle-brachial index was used in order to detect vascular injuries.

RESULTS

Ten dislocations, 30% with popliteal artery injury, were diagnosed early and received emergency treatment within 8 hours. There were associated neurological injuries in two patients. There were no amputations.

CONCLUSIONS

The systematic use of this protocol has avoided consequences of late diagnosis and has drastically reduced the abusive use of invasive tests, such as arteriography.

Diagnosis and management of knee dislocations

An acute knee dislocation is an uncommon injury, with a high rate of associated vascular and neurologic injuries as well as potentially limb-threatening complications. High-energy trauma is the most common cause of an acute knee dislocation, although lower-energy injuries, such as those sustained during athletic competition, are increasing in incidence. Injuries to the popliteal artery and common peroneal nerve are relatively common, requiring a high index of suspicion and complete neurovascular examination in a timely fashion. All cases of suspected knee dislocation should have an ankle-brachial index performed, reserving arteriography for those with an abnormal finding. Initial management consists of closed reduction, if possible, and application of a hinged brace or external fixator. Definitive management remains an area of controversy, although anatomic surgical repair or reconstruction is favored by most surgeons to help optimize knee function. Most patients treated for a knee dislocation can expect to return to their daily activities, but with less predictable returns to sporting activities.