Drawer test

Abstract: Posterolateral drawer tests and external rotational recurvatum tests are used to detect posterolateral rotatory instability. A specific manner of performance of these tests is necessary to properly interpret the nature of acute and chronic knee conditions. The posterolateral drawer test is performed at 80 degrees of knee flexion and is maximum in 15 degrees of external rotation. Since the posterior cruciate ligament is intact in posterolateral rotatory instability, the posterior drawer will be negative on maximum internal tibial rotation. Fibrous scar tissue may conceal an otherwise positive posterolateral drawer sign in the chronic condition. The external rotational recurvatum test examines the knee in extension. Tightness and spasm of the biceps femoris and semimembranosus may obscure a positive external rotational recurvatum test in the acute or chronic condition. The external rotational recurvatum test will be negative when the anteromedial and intermediate bundles of the anterior cruciate ligament are intact owing to their contact with the intercondylar shelf in extension. The posterolateral drawer and the external rotational recurvatum can be subtle tests and require careful observation for accurate evaluation of both the acute or chronic condition of the knee joint.

Abstract: Posterolateral rotatory instability of the knee, a poste rior rotational subluxation of the lateral tibial plateau in relation to the lateral femoral condyle, is an unusual condition. Twelve cases of acute posterolateral rotatory instability are presented with an average followup of 7.5 years after surgical repair. Clinical signs suggestive of this injury included posterolateral knee tenderness, and a contusion or abrasion over the anteromedial aspect of the tibia. Indications for operative repair in cluded a 2+ or greater varus instability of the knee at 30° flexion in association with a positive external rota tion recurvatum or posterolateral drawer test. At oper ation, the consistent finding was a tear in the arcuate ligament complex in all patients.Primary operative repair resulted in stable and func tional knees in 8 of 11 patients without evidence of degenerative joint disease at 7½ years postinjury. Roentgenographic evidence of degenerative joint dis ease was present in three patients, two of whom ...

Abstract: An apparently normal knee was examined in each of 100 subjects while they were under general or epidural anesthesia for an unrelated operation. The Lachman, anterior drawer, posterior drawer, and pivot-shift tests were negative in all knees. All knees were stable to varus and valgus stress at both 0 and 30 degrees of flexion. The external-rotation recurvatum test also was negative in all knees. A positive reversed pivot-shift sign was present in 35 per cent of the knees, suggesting that it may not signify abnormality, at least not without a negative test on the contralateral knee. The results of the posterolateral drawer test were variable, difficult to quantify, and did not always have a firm end-point. The amount of maximum external rotation of the tibia, measured from the reference line of the medial border of the foot, was extremely variable at both 30 and 90 degrees of flexion of the knee. External rotation, as determined by this reference, was slightly greater (averaging 9 degrees) at 90 than at 30 degrees of flexion. The normal range of maximum external rotation of the foot was 10 to 45 degrees at 30 degrees of flexion of the knee and 15 to 70 degrees at 90 degrees of flexion. The presence of a large angle of external rotation and a positive reversed pivot-shift sign correlated strongly with increased ligamentous laxity and mild varus alignment of the knee.

Abstract: Anterior cruciate ligament (ACL) deficiency can result in serious degenerative stifle injuries Although tibial plateau leveling osteotomy (TPLO) is a common method for the surgical treatment of ACL deficiency, alternative osteotomies, such as a leveling osteotomy based on the center of rotation of angulation (CBLO) are described in the literature However, whether a CBLO could represent a viable alternative to a TPLO remains to be established The aim of this study is to compare TPLO and CBLO effectiveness in treating ACL rupture First, a computational multibody model of a physiological stifle was created using three-dimensional surfaces of a medium-sized canine femur, tibia, fibula and patella Articular contacts were modeled by means of a formulation describing the contact force as function of the interpenetration between surfaces Moreover, ligaments were represented by vector forces connecting origin and insertion points The lengths of the ligaments at rest were optimized simulating the drawer test The ACL-deficient model was obtained by deactivating the ACL related forces in the optimized physiological one Then, TPLO and CBLO treatments were virtually performed on the pathological stifle Finally, the drawer test and a weight-bearing squat movement were performed to compare the treatments effectiveness in terms of tibial anteroposterior translation, patellar ligament force, intra-articular compressive force and quadriceps force Results from drawer test simulations showed that ACL-deficiency causes an increase of the anterior tibial translation by up to 52 mm, while no remarkable differences between CBLO and TPLO were recorded Overall, squat simulations have demonstrated that both treatments lead to an increase of all considered forces compared to the physiological model Specifically, CBLO and TPLO produce an increase in compressive forces of 54% and 37%, respectively, at 90° flexion However, TPLO produces higher compressive forces (up to 16%) with respect to CBLO for wider flexion angles ranging from 135° to 117° Conversely, TPLO generates lower forces in patellar ligament and quadriceps muscle, compared to CBLO In light of the higher intra-articular compressive force over the physiological walking range of flexion, which was observed to result from TPLO in the current study, the use of this technique should be carefully considered