Introduction

• ACL injuries are common, occurring in approximately one in 3000 people in the United States annually.

• ACL injuries are most commonly the result of a noncontact athletic injury; however. they can result from various forms of trauma.

• The diagnosis of an ACL tear can typically be made from a thorough history and physical examination. Imaging studies, specifically magnetic resonance imaging (MRI), can be a valuable aid in making the diagnosis and identifying associated injuries.

• Nonoperative management of ACL tears in young, active patients often fails, resulting in persistent instability, and meniscal damage. However, nonoperative management in older, more sedentary patients has been associated with good outcomes.

• Arthroscopic ACL reconstruction has been a generally successful operation at restoring knee stability and returning patients to a high level of sporting activity.

• Reconstruction can be performed with a variety of graft choices and fixation options. Overall outcomes, regardless of graft choice, have been favorable.

Figure 51-1 The Lachman test. With the knee in 20 to 30 degrees of flexion, the examiner stabilizes the femur with one hand while imparting an anterior force to the tibia with the other hand. Assessment of translation and endpoint is recorded. Translation is recorded as follows: I = 0 to 5mm, II = 6 to 10mm, III = >10mm; A = firm endpoint, B = soft endpoint.

Figure 51-1 The Lachman test. With the knee in 20 to 30 degrees of flexion, the examiner stabilizes the femur with one hand while imparting an anterior force to the tibia with the other hand. Assessment of translation and endpoint is recorded. Translation is recorded as follows: I = 0 to 5mm, II = 6 to 10mm, III = >10mm; A = firm endpoint, B = soft endpoint.

Degree of translation and presence or absence of an endpoint is assessed. The degree of laxity is graded as a comparison with the contralateral, uninvolved knee. The absence of a firm endpoint is indicative of ACL deficiency. Muscle splinting, effusion,

Figure 51-2 The pivot-shift is performed with the hip in slight abduction and with a valgus force applied to the extended knee. The knee is brought into flexion (from full extension) and the tibia reduces. The severity of the reduction (spin, jump, locked out) is graded.

and rotation of the leg may interfere with accurate Lachman testing. The anterior drawer is performed with the knee in neutral rotation and flexed to 90 degrees. The foot is stabilized with the examiner's thigh and an anterior stress is applied to the tibia. This test is not considered as sensitive for ACL deficiency as the Lachman.6 Last, the pivot-shift is used to determine the rotational competency of the ACL. A positive pivot-shift is considered pathognomonic of ACL deficiency. In the ACL-deficient knee, the tibia sits in an anteriorly subluxed and internally rotated position. An axial load and a valgus torque is applied to the knee as it is brought into flexion. When the knee reaches a position of 15 to 20 degrees of flexion, the tibia reduces, thus producing the pivot shift. This phenomenon is graded as a grade 1 (spin), grade 2 (jump), and grade 3 (transient lock) based on the degree of the reduction. The sensitivity of this maneuver is poor in the awake patient, but it is very sensitive and specific when performed in a patient under anesthesia6,7 (Fig. 51-2).

In addition to a thorough ligamentous and meniscal evaluation as described in Chapter 46, attention should also be paid to the patella. A patient with an acute patellar dislocation may present in a similar fashion and with a painful, swollen knee with a large hemarthrosis. This diagnosis must be considered when evaluating a patient with an injury suspected of being an ACL tear.

Plain radiographs are the first-line imaging modality for any acutely injured knee and should be obtained if there is any suspicion of an ACL injury. Standard posteroanterior flexion, lateral, and Merchant views should be obtained. Radiographs should be assessed for possible fractures. Occasionally, a small lateral capsular avulsion fracture of the tibial plateau can be visualized on plain films. This finding is termed a Segond fracture and has been said to be pathognomonic of an ACL injury (Fig. 51-3). Additionally, tibial spine avulsion fractures may be seen in skeletally immature and middle-aged patients with clinical examinations that are suspicious for ACL injury. In the chronic setting, intercondylar notch osteophytes, blunting of the inter-condylar eminence, and accentuation of the sulcus terminalis may be observed. This accentuation of the sulcus terminalis has been termed the lateral notch sign (Fig. 51-4). Plain radiographs are also useful for assessment of overall limb alignment and degree of degenerative changes, if present.

MRI remains the gold-standard imaging modality for ACL injury. The reported sensitivity of MRI for detecting ACL injury is in excess of 90% to 95%.8,9 Fiber discontinuity, ligament edema, and hemorrhage can be readily detected by MRI and are characteristic of an acute ACL tear (Fig. 51-5). In addition, the MRI scan often demonstrates a characteristic bone bruise pattern in the posterolateral tibial plateau and anterolateral femoral condyle with acute ACL injury. These bruises have been reported in approximately 80% of acute injuries.10,11 The significance and long-term prognostic implications of these "bone bruises" on the natural history of the ACL-deficient knee are unknown at this time11 (Fig. 51-6). MRI is also very useful for detecting associated meniscal, chondral, and ligamentous injuries, which are important to surgical planning.

Was this article helpful?

0 0
Cure Tennis Elbow Without Surgery

Cure Tennis Elbow Without Surgery

Everything you wanted to know about. How To Cure Tennis Elbow. Are you an athlete who suffers from tennis elbow? Contrary to popular opinion, most people who suffer from tennis elbow do not even play tennis. They get this condition, which is a torn tendon in the elbow, from the strain of using the same motions with the arm, repeatedly. If you have tennis elbow, you understand how the pain can disrupt your day.

Get My Free Ebook


Post a comment