3.3.2. Qualitative Data
The Lachman test is used widely in clinical setting as it is fast and easy to perform for assessing the instability of the knee . The test is performed with the patient supine and the knee relaxed at 20° to 30° of flexion. The examiner places one hand on the distal end of the thigh and the other hand behind the proximal end of the tibia. The tibia is then translated anteriorly on the femur, and the endpoint is assessed as firm (intact ACL) or soft (injured ACL). An injured ACL should be graded either I < 2 mm, II 2 to 5 mm, III > 5 mm.
The literature lacks consensus on the usefulness of the Lachman test as a measure of anterior knee stability. Its reliability and validity range from 87% to 97% and 91% to 97%, respectively [12,28,48]. One of the disadvantages of the Lachman test is the difficulty for examiners with smaller hands to perform it properly. It is restricted to examiners with larger hands to properly perform it [49,50], as it needs a firm griping of the femur to displace the tibia anteriorly. As a result, conducting the test in a prone position has been proposed and yielded a positive alternative to the Lachman test . Moreover, Muller et al.  examined the proficiency in performing the prone Lachman test as opposed to the classic Lachman. They showed that prone Lachman yielded 78% of positive predictive value while the classic Lachman 28%. The prone Lachman test uses gravity to pull down the femur, which will let the examiner grip and displace the tibia in both hands . Consequently, the size of the knee may be an important factor in deciding which knee instability measure should be used to assess knee stability.
Pivot Shift Test
Galway, Beaupre and MacIntosh  initially described the pivot shift test as an examination tool of functional knee instability. This is performed with the patient supine with the examiner standing lateral to the patient holding the knee and ankle in 20° of internal rotation, with the patient`s hip flexed to 30°. A valgus force is applied to the proximal tibia, to create impingement of the plateau on the femur. The knee is then flexed and assessed for a clunk due to the reduction of the displaced tibia on the femur, which normally occurs between 20° and 30°. The motion is then graded as: 0 = no clunk, I = glide, II = clunk and III = gross clunk with locking. A false negative may be obtained in patients with Iliotibial Band (ITB) pathology, medial collateral ligament injury, a bucket handle meniscus tear or a flexion contracture. A false positive pivot shift may be present in a patient with increased laxity. Comparison with the uninjured knee should always be undertaken.
There is a controversy in the literature on the usefulness of the pivot shift test. The controversy surrounds the various techniques used by clinicians when performing the pivot shift test. Variations exist particularly in the degree of knee flexion, hip flexion and tibial internal rotation . It is difficult to assess the effect on the test outcome of associated injuries to the knee and the limited range of motion in knees with injured meniscus . Similarly, the subjectivity on the amount of the applied valgus force whilst doing the test leads to difficulties in replicating the test for confirmation . The specificity of the pivot shift test has been shown to be dependent on whether or not the patient is anaesthetized . It ranges from 32% without to 85% with anaesthesia; this result was confirmed by Kuroda et al. , who theorised that muscular resistance can suppress the pivot shift manoeuver.
Anterior Drawer Test
The anterior drawer test specifically assesses the anterior stability of the knee . Several studies reported that clinicians use it widely in both clinics and operation theatres [16,38,54,58,59,60]. It is performed in a supine position, with the knee at 90° flexion and the hip at 45° flexion. The examiner sits on the patient’s tested foot and with one or both hands grasping the proximal end of the leg aligning the thumb(s) with the anterior joint line. The tibia is then pulled anteriorly, and an assessment is made of the relative translation of the tibia on the femur. The tibia should displace within a similar range to the sound knee. If an excessive displacement occurs in the injured knee compared to the sound knee and a soft endpoint is felt, it is assumed that there is an ACL injury yet to be confirmed with an objective knee instability measure.
The anterior drawer test has an agreement in the literature regarding its usefulness [38,59]. Mitsou et al.  highlighted the difficulty in performing the anterior drawer test at the acute stage following a suspected ACL injury. In addition, they reported specificity ranged from 78% to 99% when patients were examined under general anaesthesia. On the other hand, Scholten et al.  concluded that such a test is of unproven value. It has been shown that failure to quantify the amount of displacement of the tibia on the femur and inability to use it in the acute stage of injury were weaknesses of this test.
The rolimeter (Aircast Europa, Neubeuern, Germany) is a portable knee arthrometer used to measure anterior-posterior displacement of the tibia on the femur while performing the Lachman test . It is performed whilst the patient is positioned supine with 30° flexion of the tested knee. Next, a proximal convex pad is placed over the patella and a distal pad placed over the tibia with a strap. The two pads are connected a few inches above the limb by a steel bar. A feeler should be placed over the tibial tubercle; the Lachman test is performed after the device has been zeroed. To that end, the anteroposterior displacement of the tibia on the femur is measured in increments of 2 mm by the marks on the feeler. A difference of 4 mm or greater, in comparison with the uninjured knee, is suggestive of an ACL injury .
Rolimeter provides an economic, exact and simple device for quantifying anterior knee joint instability . Among 20 healthy participants and 18 patient with chronic ACL injury, Ganko et al.  assessed the reliability of the rolimeter as opposed to the KT-1000. In the mean knee displacement, both devices showed strong correlation (r = 0.73, p < 0.001) for the injured knees, while there was no significant correlation in their uninjured knees (r = 0.32, p > 0.10). Hence, they concluded that, with experienced examiners, the rolimeter is a valid method to assess anterior knee instability. However, its specificity as a standalone measure of knee stability (84.3) was questioned when compared to its results alongside clinical examination (92.4) . This was justified based on the fact that the rolimeter does only measure the anterior-posterior stability rather than the rotational stability of the knee . The use of the rolimeter as a standalone measure can give false negative results with the notion that knee stability is maintained by both anterior-posterior and rotational mechanical stability .
This is a computerized navigation system designed to assist surgeons during knee ligament reconstructions and arthroplasty surgery . It uses kinematic measurements along with bone-morphing technology to determine data on alignment, kinematics and morphologic characteristics of the knee . Pins are placed within the tibia and femur; attached to these pins are markers, which are detected by the computer sensors and registered relative to predefined anatomical locations. Based on the movement of these markers relative to each other, small displacements can be detected and used to quantify knee joint stability during surgery [63,64].
The navigation system remains the gold standard for the measure of anterior-posterior knee laxity due to its precision, validity and accuracy [36,45,63,64,65]. Pearls et al.  investigated the reliability and repeatability of using a knee navigation system in knee instability examination by comparing the navigation system to a robotic testing system. Intra-class Correlation Coefficients (ICC) were used to assess the correlation between the two systems. The authors reported that the surgical navigation system is a precise intraoperative tool to quantify translational and rotational knee instability. The ICCs were all statistically significant at p < 0.01, and the overall ICC was 0.9976. Continuous developments to the knee navigation system have provided the ability to measure rotational knee stability in addition to the translational stability . Nevertheless, it is strictly used in connection with surgery. The use of navigation systems is limited to surgical procedures; it is expensive, invasive and requires surgical experience, due to the need for accurate fixation of sensors in the femur and tibia . Thus, it is a good research and clinical tool; however, it cannot be used on-field or within a clinical setting to aid in decision making .
The Genucom Knee Analysis System
The Genucom knee analysis system (FARO Medical Technologies Inc., Montreal, QC, Canada) is a computerized device developed in the1980s to objectively measure knee stability in different planes (e.g., sagittal and frontal planes) . The participant’s tested knee is positioned in 20° flexion and the thigh secured with restraints. An electro-goniometer is attached to the thigh, with anatomical markers placed on the medial and lateral femoral condyle, patella and tibial crest. The markers are digitized, and then, the relative displacement of the knee is recorded in addition to the distance between the markers .
The Genucom knee analysis system is the only objective instrument to provide a multiplanar measure of knee stability, but it is more complicated and time consuming to use compared to other measures [30,67]. Furthermore, it has poor sensitivity, and its cost-effectiveness has been questioned . As a result, it has fallen out of common use.
The KT-1000/KT-2000 Arthrometer
- Fino. Jerez. Откуда-то сверху накатывали приглушенные волны классической музыки.