Management in the Emergency Room

2 Management in the Emergency Room Michael E. Hantes and Konstantinos Banios 2.1 Introduction Knee dislocation, or multi-ligamentous injury of the knee, is recognized to be a rare injury, quoted to represent between 0.02% and 0.2% of all orthopedic trauma [1, 2]. However, this figure probably does not represent the whole truth, because of a (common) missed diagnosis after a spontaneous reduction of the dislocation [3]. Dislocation entails the complete disruption of the tibio-femoral articulation (Fig. 2.1), which most commonly presents as an anatomically reduced but highly unstable knee, requiring rupture of a minimum two major stabilizing ligaments. Knee dislocations are potentially limbthreatening injuries, with a high risk of vascular compromise, varied widely, ranging from 3.3% to 64% [4]. Radiographic evidence of dislocation is not always available, and the clinician has to be aware of other signs of a dislocation that may have spontaneously reduced like an hematoma of the popliteal fossa (Fig. 2.2). Approximately 50% of knee dislocations are spontaneously reduced prior to the examination of a clinician. M. E. Hantes (*) · K. Banios Department of Orthopedics, Faculty of Medicine, University of Thessaly, Larisa, Greece e-mail: [email protected] Most knee dislocations are the result of highenergy mechanisms [5]. However, nowadays as obesity becomes a worldwide medical issue, even low-velocity injuries such as ground level falls may lead to knee dislocation. Therefore, evaluating physicians should maintain a high suspicion for a knee dislocation in any obese patient who presents with knee pain following a seemingly innocuous injury. Careful history and physical examination in a systematic approach will aid in identifying patients at risk for this injury. The three most common mechanisms of these injuries include: (a) High-energy trauma due to motor vehicle collision (almost 50%). (b) Sport injuries (33%). (c) Simple falls (12%). A patient with a dislocated knee should be approached very carefully in the emergency department in order to recognize, deal with this severe injury, and avoid misdiagnosis or other complications. 2.2 History and Physical Examination The mechanism of injury is an important factor in guiding evaluation of a knee injury in the emergency department (ED) and in predicting the © ISAKOS 2019 F. Margheritini et al. (eds.), Complex Knee Ligament Injuries, https://doi.org/10.1007/978-3-662-58245-9_2 19 20 Fig. 2.1 Anteroposterior (a) and lateral (b) X-rays of a dislocated knee M. E. Hantes and K. Banios a b Fig. 2.3 Gross deformity of the knee due to knee dislocation and anteriorly dislocated tibia Fig. 2.2 Extensive hematoma of the popliteal fossa and posterior thigh after a knee dislocation ultimate diagnosis. Consider the direction of the force applied to the knee and the position of the knee at the time the force was applied. Inquire about the ability to bear weight immediately after the injury, the development of restrictions of range of motion, the location of pain, loss of sensation, any new swelling and the period of time over which it occurred, and whether a “pop” was felt or heard by the injured patient. As knee dislocations are usually associated with other injuries, the clinician must initially follow the ATLS principles. So it is crucial not to concentrate only to the injured knee but inspect the whole body for any concomitant injury. Hemodynamic instability may result from internal injury or fractures and is the most important consideration for the orthopedic surgeon. As the patient is stabilized, it is important to inspect the affected limb so as to recognize any skin injury (15–30% of knee dislocations are open) [6, 7]. Moreover, the presence of any obvious deformity can reveal the direction of the dislocated tibia (Fig. 2.3). Compare the affected knee with the contralateral one for reference and symmetry. – Palpate bony structures of the knee and note any tenderness. – Patellar tap test can reveal joint effusion. – Note the range of motion (passive and active). – Assess distal pulses and capillary refill distal to the injured knee. – Check for any sensory and motor dysfunction of the affected limb. 2 Management in the Emergency Room 2.3 Vascular Examination The incidence of popliteal artery injury is 3.3%– 64% [4]. Popliteal artery is fixed proximally onto the medial femoral epicondyle at the fibrous insertion of adductor magnus and distally tethered by the tendinous arch of soleus; movement of the artery is restricted leading to traction injury. Because vascular injury is potentially limb threatening, early identification of vascular injury is critical. A delay in the diagnosis increases the time of warm ischemia and the risk for irreversible injury, resulting in the possible need for an above the knee amputation. Up to 20% of patients with vascular compromise will eventually require amputation, increasing to more than 80% with an ischemic time of over 8 h; therefore, early recognition and management of a compromised limb is vital [8]. A recent review of available literature did not demonstrate any association between direction of dislocation and vascular insult [9]. A clinician who suspects a knee dislocation has to examine the leg for two essential things in order to assess vascular integrity of the leg. First, palpate dorsalis pedis and posterior tibial pulses bilaterally and assess for any asymmetry. In the absence of any asymmetry, further assessment is not necessary [10, 11]. Second, the ankle-brachial index (ABI), which is the ratio of the systolic blood pressure measured at the ankle to that measured at the brachial artery, should be calculated. To perform this, a clinician needs a manual blood pressure cuff and a Doppler probe. With the patient in the supine position, a blood pressure cuff is placed on the affected ankle above the malleoli. The ultrasound transducer is used to locate the dorsalis pedis or posterior tibial artery signal. The blood pressure cuff is inflated while listening to the Doppler signal. Once the signal has disappeared, the pressure in the cuff is slowly released until the Doppler signal can be heard again. The pressure at which the Doppler signal in the dorsalis pedis or posterior tibial artery returns is the systolic 21 blood pressure value for the ankle. For the brachium, the blood pressure cuff is placed on the arm, and the brachial pulse is located in the antecubital fossa using the ultrasound transducer. The cuff is inflated until the Doppler signal from the brachial artery disappears. The cuff is then gently relieved of pressure until the signal in the brachial artery returns. The pressure at which the Doppler signal returns is the systolic blood pressure in the brachium. To calculate the ABI, the systolic blood pressure measured at the ankle is divided by that measured at the brachial artery. A ratio of less than 0.9 is considered abnormal and necessitates further investigation with arteriography. On the contrary, if the ABI is greater than 0.9, it has been shown that the risk of major arterial lesion approaches 0% [12]. For further investigation, CT angiogram (CTA) is mostly preferred (Fig. 2.4), as it provides a higher sensitivity and specificity and almost one fourth less radiation than conventional one [13]. MR arthrography also shows potential in this setting through its convenience of including venous contrast while conducting a conventional MRI to evaluate ligamentous injury [14]. An algorithm employed at the University of Washington Medical Center for the diagnosis of vascular injury following multiple-ligament knee injuries is presented in Fig. 2.5. Fig. 2.4 CT angiogram image of a patient with popliteal artery occlusion after a knee dislocation 22 M. E. Hantes and K. Banios Diagnose knee dislocation Immediate reduction Physical examination ABI Distal pulse assymetry Distal pulse present Well perfused limb ABI > 0.9 OR Distal pulse present and well pefused limb with ABI < 0.9 Distal pulse absent OR Other signs of vascular injury (distl ischemia, active hemorrhage) Observation for 24 h Obtain arterial and venous duplex 48 h prior to surgery Arteriogram Surgical exploration Fig. 2.5 Algorithm employed at the University of Washington Medical Center for the diagnosis of vascular injury following multiple ligament knee injuries 2.3.1 Neurologic Examination The physical examination should include a detailed neurologic examination including sensation in the tibial, deep peroneal, and superficial peroneal distributions to light touch, pinprick. Motor examination including the flexor and extensor hallucis longus, tibialis anterior, and gastrocnemius as well. The incidence of nerve injury associated with knee dislocation ranges from 4.5% to 40.0%. Most commonly, the common peroneal is the injured nerve. The nerve is at risk for injury as well, similar to the artery, due to its anatomic constraints both proximally and distally. The fibular neck tethers the nerve proximally, and the fibrous arches of the intermuscular septum form the distal tether. Common causes of nerve injuries are fractures (e.g., lateral tibial condyle, fibula head) and tractions of the nerve due to varus stress or hyperextension. Unfortunately, recovery of patients with a neurologic deficit is unpredictable. The outcome depends on the location, the severity, the time of injury, and the age of the patient. Peripheral peroneal nerve injuries in young patients are associated with a better prognosis. 2 Management in the Emergency Room 2.4 Plain X-Rays Frontal and lateral plain films are performed as a standard in the emergency department. These should be performed before (evaluation for concomitant fractures such as Segond or other fractures and direction of displacement) and after reduction to confirm proper joint articulation and congruency. CT after performing reduction is recommended if a fracture is revealed at X-rays. MRI is helpful preoperatively for the diagnosis of ligamentous, meniscal, and articular damage, but it is not necessary in the emergency department. However, it is mandatory after initial management to reveal the whole spectrum of injuries. 2.4.1 23 Reduction of the Dislocation After X-ray confirmation of a knee dislocation, a reduction of the dislocation should be performed. The reduction of the knee should be attempted with the patient under sedation either in the emergency department or at the operating room, for a successful reduction is essential to make a maneuver that reverses the deforming force. Often, gentle in-line traction attempting to bring the knee into extension is enough to reduce a dislocated knee. No manual pressure should be used to aid in any direction, especially in the popliteal fossa, to avoid iatrogenic neurovascular injury. After reduction is done, the knee should be splinted in 20° of flexion so as to provide stability of bony and neurovascular structures, relaxation of soft tissues, and pain relief to the patient. Moreover the splint must prevent posterior subluxation of the tibia to minimize traction of vessels. Opening a window to splint is crucial to allow vascular evaluation of the foot. Successful reduction is confirmed with knee X-rays. If the reduction is unsuccessful, the patient should be taken urgently to the operating room for a reduction under general anesthesia (in many cases, the irreducible knee has pinched or threatened skin, particularly on the medial aspect of the knee). If closed reduction performed under anesthesia is unsuccessful, the surgeon should proceed to an open reduction of the knee. One of the Fig. 2.6 The dimple sign: skin dimple between the medial femoral condyle and the medial tibial plateau. This patient had an open unrecognized knee dislocation and managed with wound closure initially reasons for an irreducible knee dislocation is the so-called dimple sign. The dimple sign: When the knee is gently brought into extension, a worsening skin dimple between the medial femoral condyle and the medial tibial plateau can be a sign that closed reduction will be unsuccessful. The skin dimple is a sign that the medial femoral condyle has buttonholed through the medial joint capsule, and the MCL has become entrapped and is being pulled into the joint with the gentle traction (Fig. 2.6). Multiple case reports cite this as a sign for an irreducible knee dislocation and recommend open reduction in the operating room [15]. Unfortunately, it may not be visualized in many cases due to diffuse swelling of the knee. A midline surgical incision with a medial parapatellar arthrotomy is useful to address the acute dislocation and later ligament reconstruction. A recent review of the literature identified that KD-III is the predominant injury pattern in irreducible dislocations, which refer to ruptures of ACL, PCL, and MCL or LCL (79.5%) [16]. The interposed tissue is likely to be MCL or medial retinaculum, but all surrounding structures cannot be neglected. Once the knee is reduced, repeat neurologic and vascular examination are done immediately. With any vascular compromise or asymmetry in ABIs whereby the affected leg is less than 0.9, surgical exploration is warranted. 24 M. E. Hantes and K. Banios Compartment syndrome development is another potential complication of a knee dislocation. High suspicion of compartment syndrome and close monitoring of the leg, through clinical examination or through invasive measurements of the intra-compartmental pressure (ICP), should be performed. In case of compartment syndrome development, immediate fasciotomy of all four compartments is necessary, and it should be performed without any delay. Moreover, care must be taken not to elevate the injured limb above heart level in order to avoid perfusion depression. 2.5 Examination of Knee Stability Examination of ligamentous integrity is usually limited secondary to patient discomfort, and some of the most specific diagnostic tests require patient cooperation, which is difficult under these circumstances. However, the physician could attempt a gentle examination, and probably intraarticular injection of lidocaine after aspiration of any hemarthrosis can aid in patient’s comfort. Clues to ligament injury in a spontaneously reduced knee dislocation are any asymmetry in the joint space, minor subluxations in any direction, and Segond fractures. The Lachman test and the anterior drawer test (ACL rupture), varus/valgus stressing (MCL/ LCL compromise), and posterior sag (PCL disruption) are the most reliable maneuvers in the acute setting. The pivot shift, dial test, reverse pivot shift, and weight-bearing examinations are impractical at the bedside but can aid in the diagnosis while under anesthesia. 2.6 Emergent Surgery Absolute surgical indications in patients with a knee dislocation include (a) vascular injury, (b) irreducible dislocations, (c) gross instability on examination with failure to maintain joint reduction, (d) open injuries, and (e) inability to tolerate mobilization in a brace, whether due to pain or noncompliance [17–19]. Associated fractures, avulsion-type injuries, and ligamentous hypermobility often benefit from surgical repair, although this can be done in a later stage. The determination of instability is made with a thorough ligamentous examination and an examination under anesthesia with fluoroscopic stress views in the operating room. If a patient has gross instability and reduction cannot be maintained, then there is a risk of repetitive trauma to the posterior vascular structures (popliteal artery) making them more vulnerable for thrombosis, and this is an indication to apply an external fixator to maintain stability. As for the vascular injury, the rationale for external stabilization is: (a) To stabilize the vascular repair in case of a vascular injury which requires surgical intervention. (b) To protect from further vascular trauma when a vascular surgery is not necessary. In case of an open dislocation, it is obvious that as an open trauma the surgeon has to do a thorough irrigation and debridement of foreign material and nonviable tissues. Furthermore placing an external fixator prevents from further trauma to the soft tissues and also makes mobilization of the patient possible. Another indication for placing external fixator is patient’s inability to tolerate mobilization in a brace either due to pain (probably the brace does not hold the limb in a stable fashion) or due to incompliance especially in obese patients. As external fixator is applied, it is mandatory to perform X-rays in order to confirm the correct articulation of the joint and the correct positioning of the pins. The advantages of using spanning external fixation include skin assessment, compartment pressure observation, and monitoring the neurovascular status of the affected limb. The main indications for initial application of external fixation are: 1. 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