TABLE 20-2 External Rotation Limits (100 N Posterior Force, 5 Nm External Moment). 20-5C), indicating that these structures are the primary restraint to this knee motion. When the PCL was also sectioned, the lateral tibial plateau demonstrated a gross posterior subluxation, with a mean posterior translation of 34.2 ± 3.5 mm (23.5 mm from normal). Soft tissue attachments to lateral meniscus and posterior tibia. Statistically significant increases were found at all flexion angles for both cut states. FIGURE 20-1 The curves show the limits of anterior and posterior translation (vertical axis) when a 100-N anteroposterior (AP) force was applied. An anatomic reconstruction of the PLS with the goal of restoring the PLC and meniscus attachments, PMTL, and FCL is described in. PCL insufficiency can be detected on physical examination using a number of … PLS primary restraint adduction-abduction rotation limits. The normal knee motion limits to internal and external tibial rotation are shown in Figure 20-3A. B, Abnormal anterior translation of the medial tibial plateau under loading conditions of 5 Nm (at 30° of knee flexion). Sectioning only PLS: mean increase posterior translation lateral tibial plateau, 8.0 mm (30° flexion) over intact state. The PCL originates from lateral side of posteromedial femoral condyle and attaches to the extreme posterior intracondylar tibial region. The abnormal lateral joint opening places high tensile forces on the PMTL that is not designed to resist varus moments (in the absence of a functional FCL). All of these structures are illustrated in Chapter 2, Lateral, Posterior, and Cruciate Knee Anatomy. Application of the 50-N posterior tibial force had no significant effect on the mean force in the PCL in the intact specimens (INTACT). The goal is to restore normal load-sharing in which the majority of varus-valgus loads and internal-external rotation torques are placed upon the medial and lateral structures and not the cruciate ligaments. The data demonstrate that the FCL is the primary restraint for lateral joint opening, with further increases after the remaining PLS are sectioned. Sectioning PCL and PLS: increases posterior translation medial and lateral tibial plateaus (30°, 90° flexion). This study showed that in normal knees under the conditions of external tibial rotation (5 Nm) and a posterior force (100 N) at 30° of flexion, the lateral tibial plateau displaced a mean of 7.5 ± 2.9 mm. The limit of posterior translation, and therefore the amount of increase, is controlled by the remaining intact structures. The Function of the Meniscofemoral Ligaments. strongest and largest intra-articular ligament in human knee and the primary posterior stabilizer of the knee. Am J Sports Med 21:407–414, 1993.). Increases in external tibial rotation at 90° indicate injury to both the PLS and the PCL, consistent with the dial test (see. Posterior cruciate ligament pain injuries are classified according to the amount of injury to the functional ligament: Grade 1 PCL Sprain: A small partial tear; Grade 2 PCL Sprain: A near complete tear; Grade 3 PCL Tear: A complete tear whereas the ligament becomes non-functional; usually this occurs with injuries to other knee ligaments (most commonly the … Once the PLS are removed, the PCL becomes a primary restraint and large increases in the adduction limit occur with knee flexion. Statistically significant increases in external rotation were found in the ACL + POP + PMTL cut state at 60° of flexion and higher. As described previously, Grood and coworkers. Even so, there are posteromedial oblique capsular fibers from the medial femoral condyle to the tibia, just posterior to the SMCL, that resist internal tibial rotation and posterior tibial translation (after PCL sectioning). A review of the function and biomechanics of the meniscofemoral ligaments. PCL primary restraint to posterior tibial translation throughout knee flexion. This represents the displacement required to tense the PCL to resist further posterior subluxation of the lateral tibial plateau. There are few published data on the true millimeters of tibial subluxation of the medial and lateral compartments (rotatory subluxations) that occur after knee ligament injuries, which are discussed in further detail later in this chapter. There was a large range of posterior tibial subluxations at both 30° (Fig. Statistically significant increases in external rotation were found at all flexion angles for the ACL + POP + PMTL + FCL and the ALL cut states. Cadaveric studies measured limits of anteroposterior (AP) translation, internal-external tibial rotation, varus-valgus rotation under specific forces and moments. An anatomic reconstruction of the PLS with the goal of restoring the PLC and meniscus attachments, PMTL, and FCL is described in Chapter 22, Posterolateral Ligament Injuries: Diagnosis, Operative Techniques, and Clinical Outcomes. It should be noted that a complete description of the translation limits requires an anatomic measurable point on the tibia, which is selected at the midcoronal point of the tibia. (From Grood, E. S.; Stowers, S. F.; Noyes, F. R.: Limits of movement in the human knee. FIGURE 20-12 Limits of external rotation with a 5-Nm moment for intact specimens and with structures cut. A, Intact knees. Conversely, in knees with physiologic laxity, large increases in posterior tibial plateau subluxation may be detected after isolated PLS rupture because there is little resistance provided by the PCL. 2011 Sep. 23(3):135-41. . Increased posterior translation at 30°–45° flexion associated injury to posterolateral structures (PLS), medial ligament structures. The open circles represent the intact knee. It becomes thinner as it approaches the tibia, and it is partially embedded within the joint capsule. Source: Gupte CM, et al. FIGURE 20-3 The limits of internal and external rotation of the tibia when a 5-N torque was applied. The limits of adduction and abduction rotation when a 20 Nm moment was applied. Increases in the limits to adduction (varus angulation) are shown after sectioning the FCL, the posterolateral capsule (PLC; PMTL and PLC), and all structures (PCL, FCL, PMTL, and PLC). Subsequent sectioning of the POP (dark square) resulted in large increases in movement limits. There was no significant increase in posterior translation of the medial tibial plateau at either flexion angle. Additional PLS that may be injured and require repair are the iliotibial band femoral and tibial attachments, meniscal tibial and femoral attachments (including fascicles), the fabellofibular ligament, and the lateral and anterior capsule. POP, popliteus tendon. Under the same loading conditions at 90° of flexion, sectioning only the PLS resulted in a small (2.7-mm) increase in posterior translation of the lateral tibial plateau. to prevent hyper-extension and limits internal rotation, adduction and abduction at the knee joint. When the knee is in extension, it makes an almost 90º turn as it passes anterosuperiorly. Even though buckle transducers have inherent problems in truly measuring ligament tensile-resisting loads, the results show that all three structures are important in resisting external tibial rotation loads and the presumed importance of anatomic reconstruction of these structures. Robinson and coworkers74 conducted a cadaveric study of the medial and posteromedial structures and could not identify a distinct separate POL structure, but did identify an oblique portion of the PMC at which fibers could be tensioned under internal tibial rotation loading. Incidence of posterior cruciate ligament (PCL) injuries is variable. Substantial differences in clinical tests “tight” versus “loose” jointed knees. 11, 45, 47 The mean values of external tibial rotation and the millimeters of AP translation for medial, central, and lateral tibial reference points are shown for 30° and 90° of knee flexion under the predetermined loads applied to the knee joint (100 N posterior load, 5 Nm external rotation torque). Note that increases occur at all flexion angles. PLS, posterolateral structures including fibular collateral ligament (FCL). The data also confirm that the diagnosis of injury to the PLS is based on the final posterior position of the lateral tibial plateau and not on the degrees of external tibial rotation. The millimeters of posterior subluxation of the medial and lateral tibiofemoral compartments after sectioning the PCL and PLS were measured in whole cadaver lower limbs in a testing apparatus previously described.64 The position of the lateral and medial tibial plateaus was determined by three reference points: the AP translation of a point located at the center of each plateau, and the medial and lateral location of points located midway between the tibial edges and the joint centers. The importance of load-sharing of the PLS with the PCL is demonstrated in many studies, which reinforces the need in knees with combined PCL-PLS ruptures to also perform posterolateral reconstructive surgery. It should be noted that a complete description of the translation limits requires an anatomic measurable point on the tibia, which is selected at the midcoronal point of the tibia. However, the problem remains that the single reconstruction will be subjected to much higher in vivo loading conditions with the added load-sharing of the remaining competent PLS. In intact knees that had low values for posterior tibial displacements, ligament cutting resulted in a small increase in posterior subluxation, which was often lower than that measured in the normal “physiologically loose” knees. PCL, posterior cruciate ligament and ligaments of Humphry and Wrisberg cut in addition to the PLS and FCL. The normal anterior and posterior translation knee limits are shown in. Cruciate ligaments of knee ( attachment , function & injury) English , DR. SAMEH GHAZY - YouTube. The data show that the PCL is a primary restraint to posterior tibial translation throughout knee flexion, with the exception of a small increase in posterior translation at full extension when the PLS are cut. Increases in external tibial rotation at 90° indicate injury to both the PLS and the PCL, consistent with the dial test (see Chapter 22, Posterolateral Ligament Injuries: Diagnosis, Operative Techniques, and Clinical Outcomes). Application of the 50-N posterior tibial force had no significant effect on the mean force in the PCL in the intact specimens (INTACT). Statistically significant increases in external rotation were found at all flexion angles for the ACL + POP + PMTL + FCL and the ALL cut states. (1-tailed test, *P < .05; ***P < .001 after correction of multiple comparisons). : The role of the lateral extra-articular restraints in the anterior cruciate ligament–deficient knee. FIGURE 20-16 Tibiofemoral position at 30° of knee flexion. All of the PLS provide important restraints to external tibial rotation, whereas the PFL serves as a secondary restraint in providing a fibular origin to the PMTL. The purpose of this chapter is to provide a summary of the important biomechanical principles gained from studies from the authors’ laboratory and other investigations regarding the posterior cruciate ligament (PCL) and posterolateral structures (PLS). LaPrade and colleagues41 conducted an in vitro cadaveric knee study in which a specially designed buckle transducer was attached to the FCL, popliteus tendon, and PFL. These data agree with the external tibial knee motion limits previously reported,25 in which small and insignificant increases in external tibial rotation occurred at 90° after PLS sectioning. C, Abnormal posterior translation of the lateral tibial plateau plus abnormal anterior translation of the medial tibial plateau after sectioning both the medial and the lateral ligament structures. Application of the 50-N posterior tibial force had no significant effect on the mean force in the PCL in the intact specimens (INTACT). Sectioning the PFL in the intact knee produced no statistically significant changes in motion limits, whereas sectioning both the popliteus tendon and the PFL together (removing the function of the PMTL) produced a small increase in external rotation from 3° to 5°. J Bone Joint Surg Am 75:387–394, 1993.). This indicates that tests for rotatory subluxations of the knee joint are limited by the ability to quantitatively determine the millimeters of AP translation of the medial or lateral tibiofemoral joint under external rotation loads and variability between examiners should be expected. The knee is composed of four major ligaments: the ACL, lateral collateral ligament (LCL), medial collateral ligament (MCL), and posterior cruciate ligament (PCL). If playback doesn't begin shortly, try restarting your … The PCL and PLS were sectioned in 15 knees first separately and then in combination to measure the resultant abnormal knee motion limits to simulate isolated and combined ligament ruptures. The posterior cruciate ligament prevents the femur from sliding forward on the tibia (or the tibia from sliding backward on the femur). A series of studies were conducted in cadaveric knees to measure the limits of anteroposterior (AP) translation, internal-external tibial rotation, and varus-valgus rotation (using a six-degrees-of-freedom electrogoniometer) under specific forces and moments with a verified testing apparatus previously described. The knee joints were subjected to AP forces (67 N), varus-valgus torques (12 Nm) and internal-external rotation torques (6 Nm). FIGURE 20-13 Limits of external rotation with a 5-Nm moment for intact specimens and with ACL + ALS (iliotibial band and anterolateral capsule) + FCL and ALL structures (ACL + ALS + FCL + PMTL + POP) cut. Posterior subluxation medial and lateral tibiofemoral compartments measured after sectioning posterior cruciate ligament (PCL), posterolateral structures (PLS). An in vitro ligament sectioning study in cadaveric knees. The PLC slackens with knee flexion, providing less of a contribution to these motions. The primary posterolateral structures of the knee joint are the fibular collateral ligament (FCL) and popliteus muscle-tendon-ligament unit (PMTL), including the popliteofibular ligament (PFL) and posterolateral capsule (PLC). The degrees of external rotation and the millimeters of AP translation for medial, central, and lateral points are shown for two specimens, one with the least posterior tibial subluxation and one with the greatest posterior tibial subluxation. In knees with physiologic laxity, large increases in posterior tibial plateau subluxation may be detected after isolated PLS rupture because there is little resistance provided by the PCL. The limits to adduction (varus angulation) are graphed in Figure 20-625 after sectioning the FCL, the PLS (PMTL and PLC), and all structures (PCL, FCL, PMTL, and PLC). 20-18). In acute knee injuries, this fibular attachment should be repaired if possible; however, graft reconstruction for the FCL and popliteus tendon tibial-femoral attachments is advocated (see Chapter 22, Posterolateral Ligament Injuries: Diagnosis, Operative Techniques, and Clinical Outcomes). The intact FCL limits external rotation at all flexion angles after the ACL + POP + PMTL are sectioned. The PCL and PLS were sectioned in 15 knees first separately and then in combination to measure the resultant abnormal knee motion limits to simulate isolated and combined ligament ruptures.25 The PLS in this investigation included the FCL, PMTL, and PLC. In a knee with a combined deficiency of the PCL and the PLS, the abnormal posterior tibial translation is at least four to five times the normal limit throughout knee flexion. For example, when 15° of increased external tibial rotation is measured after cutting the PLS, the resultant abnormal millimeters of posterior translation of the lateral tibial condyle are unknown. Subsequent sectioning of the POP (dark square) resulted in large increases in movement limits. This is the amount that the clinician may palpate on the lateral tibiofemoral step-off with external tibial rotation in knees with ruptures to the PLS (compared with the opposite knee). In these ligament-cutting experiments, the popliteus tendon was sectioned from the femoral attachment, which effectively removed the entire popliteus muscle tendon and PFL static function. Posterior tibial translation (PTT) in response to a posterior load of 134 N (mean ± standard deviation [SD]). The objective of the study was to quantify the multidimensional deformation of the posterior cruciate ligament. [Guideline] Lee BK, Nam SW. Rupture of posterior cruciate ligament: diagnosis and treatment principles. Only small increases were noted after sectioning the PFL as long as the popliteus tendon attachments remained intact. 20-3B). J Bone Joint Surg Am 69:233–242, 1987.). Many structures work in synergy to resist hyperextension, and it is therefore not surprising that sectioning only the PLS or PCL results in a small increase. Proprioceptive function after isolated single-bundle posterior cruciate ligament reconstruction with remnant preservation for chronic posterior cruciate ligament injuries. The resisting function of the FCL, popliteus tendon, and PFL is described in separate studies later in this chapter. J Bone Joint Surg Am 70:88–97, 1988. Otherwise, the majority of forces are placed on the ACL or PCL grafts, which may stretch out or fail postoperatively. The normal limits of adduction and abduction rotation are shown in Figure 20-5A. In a separate study in the authors’ laboratory, Wroble and associates97 reported the effect on external tibial rotation when only the popliteus tendon was sectioned in ACL-deficient knees (Fig. The PMTL includes (1) the muscular tibial origin, (2) the fibular origin (PFL), (3) the merging of both of these components to the popliteal tendon inserting on the lateral femoral condyle, (4) the inferior and superior popliteomeniscal fascicles forming the popliteal hiatus, and (5) the soft tissue attachments to the lateral meniscus and posterior tibia. (A–C, From Pasque, C.; Noyes, F. R.; Gibbons, M.; et al. This is because it is also necessary to measure and compute the center of tibial rotation to determine the effect of the increase in degrees of external tibial rotation on the lateral and medial tibiofemoral compartments. No change was found in external tibial rotation. A, Intact knees. There are three possible positions for each plateau: anterior subluxation, normal position, or posterior subluxation. The static stabilizing function of the PMTL that requires surgical reconstruction has been debated. Note that increases occur at all flexion angles. The authors concluded that the POL has a much larger role than the SMCL and DMCL in resisting posterior tibial translation and internal tibial rotation. In another group of knees, the PCL, FCL and PLC were first sectioned, followed by the PFL and then the popliteus tendon. The authors have encountered knees requiring revision of a failed posterolateral procedure in which only the PMTL was reconstructed, leaving a partially or completely insufficient FCL. The goal is to restore normal load-sharing in which the majority of varus-valgus loads and internal-external rotation torques are placed upon the medial and lateral structures and not the cruciate ligaments. 8. Knee Surg Sports Traumatol Arthrosc. The effect of sectioning the secondary medial restraints resulted in a marked increase in posterior tibial translation. The increases in the mean force in the ACL after ligamentous section were significant at all angles of flexion; the increases in the mean force in the PCL were significant from 45° to 90° of flexion. The degrees of external rotation and the millimeters of AP translation for the medial, central, and lateral points are shown for two specimens, one with the least posterior tibial subluxation and one with the greatest posterior tibial subluxation (100 N posterior load, 5 Nm external rotation torque). FIGURE 20-10 Graph shows the increase in external rotation (A), varus rotation (B), and posterior translation (C) from the intact knee when the PFL and popliteus tendon were sectioned. The normal knee motion limits to internal and external tibial rotation are shown in Figure 20-3A. PCL, posterior cruciate ligament and ligaments of Humphry and Wrisberg cut in addition to the PLS and FCL. In acute knee injuries, this fibular attachment should be repaired if possible; however, graft reconstruction for the FCL and popliteus tendon tibial-femoral attachments is advocated (see Chapter 22, Posterolateral Ligament Injuries: Diagnosis, Operative Techniques, and Clinical Outcomes). 20-5B). Unlike the anterior cruciate ligament (ACL), the posterior cruciate ligament (PCL) has an intrinsic ability to heal and may regain continuity following an injury; however, in a PCL-deficient knee, gravity and the forces on the joint from the hamstring muscles can potentially cause the tibia to be positioned in a posteriorly subluxed location relative to the femur [ 17, 25, … B, PCL is cut first. Classification rotatory subluxations based on final position (translation, millimeters) of medial and lateral tibial plateaus under defined loading conditions. A, Intact knees. Sectioning only the PLS resulted in a mean increase in posterior translation of the lateral tibial plateau of 8.0 mm at 30° of flexion over the intact state (P < .01), and a smaller increase of 2.7 mm at 90° of flexion. After sectioning the FCL and the other PLS, large increases were noted in resisting tensile forces in both cruciate ligaments under varus loading (Fig. The data demonstrate that the FCL is the primary restraint for lateral joint opening, with further increases after the remaining posterolateral structures are sectioned. In these ligament-cutting experiments, the popliteus tendon was sectioned from the femoral attachment, which effectively removed the entire popliteus muscle tendon and PFL static function. 20-16) and 90° of knee flexion (Fig. 20-18). Sectioning PCL and PLS: further increase in external tibial rotation (30°, 90° flexion). FIGURE 20-18 Three types of tibiofemoral situations observed with increased external tibial rotation. It should be noted that a complete description of the translation limits requires an anatomic measurable point on the tibia, which is selected at the midcoronal point of the tibia. The Posterior Cruciate Ligament (PCL) is one of the four major ligaments of the knee joint that functions to stabilize the tibia on the femur. Sectioning both the PCL and the PLS caused significant increases in posterior translation of both the medial and the lateral tibial plateaus at 30° and 90° of flexion (, The mean values of the external tibial rotation limits for the intact knees and after sectioning the PLS and PLS/PCL are shown in, External Rotation Limits (100 N Posterior Force, 5 Nm External Moment). (From Petersen, W. J.; Loerch, S.; Schanz, S.; et al. All of the biomechanical studies show the effects of the PLS at the maximum limits of internal-external rotation under defined torques. It is important to note that the posterior subluxation of the lateral tibial plateau varied from 10 mm to 18 mm at 30° of flexion and from 9 mm to 18 mm at 90° of flexion. The ligament sectioning of the PLS was varied in order to more precisely define the restraining function of the individual structures. Arthroscopically Pertinent Anatomy of the Anterolateral and Posteromedial Bundles of the Posterior Cruciate Ligament Categories Muscles Tendons Tags Knee, Muscles Tendons, Nerves, Tibia and Fibula Post navigation. Its mean length is 38 mm and mean width is 13 mm. The data shown in Figure 20-9 demonstrate the increase in posterior tibial translation after sequential ligament sectioning of the medial and posteromedial structures. 20-3C), which is greatest at 30° of knee flexion. FIGURE 20-17 Tibiofemoral position at 90° of flexion. C, Posterolateral structures (FCL, capsule, PMTL) are cut first. FIGURE 20-2 Severe posterior tibial subluxation is shown in a chronic PCL-deficient knee, which is either due to physiologic laxity of the remaining secondary restraints or the result of a traumatic injury. There are few published data on the true millimeters of tibial subluxation of the medial and lateral compartments (rotatory subluxations) that occur after knee ligament injuries, which are discussed in further detail later in this chapter.64. C, Posterolateral structures (FCL, capsule, PMTL) are cut first. Posterior subluxation medial and lateral tibiofemoral compartments measured after sectioning posterior cruciate ligament (PCL), posterolateral structures (PLS). It also helps prevent hyperextension of the knee, and resistance to … All of the biomechanical studies show the effects of the PLS at the maximum limits of internal-external rotation under defined torques. : Posterior subluxations of the medial and lateral tibiofemoral compartments. Sectioning both the PCL and the PLS caused significant increases in posterior translation of both the medial and the lateral tibial plateaus at 30° and 90° of flexion (P < .01). Anatomy of the Upper Limb. 100 N force applied to determine the AP limits, 5 Nm for internal-external rotation limits, 20 Nm for adduction-abduction (varus-valgus) limits from 0° to 100° of knee flexion. With progressive knee flexion, the FCL provides a higher contribution to varus rotation and the PMTL provides a higher contribution to resisting external tibial rotation and posterior tibial translation. The limits of adduction and abduction rotation when a 20 Nm moment was applied. Effect of sectioning the posterior cruciate ligament and posterolateral structures. Am J Sports Med 21:407–414, 1993.). The limits to adduction (varus angulation) are graphed in. In a separate study in the authors’ laboratory, Wroble and associates97 reported the effect on external tibial rotation when only the popliteus tendon was sectioned in ACL-deficient knees (Fig. 20-14) of flexion. Considerable variability was present between specimens in the amount of measured external tibial rotation at 30° (see Fig. 20-17). Abstract. Effect on Internal-External Tibial Rotation Limits. This is because the posterior cruciate ligament has a dense sheath that protects the posterior cruciate ligament while it is healing. The difference between the ACL + ALS + FCL and the ALL curves represents the restraining function of the PMTL and POP toward external rotation. The FCL and PMTL provide important contributions and act together at low- to mid-flexion positions. (From Noyes, F. R.; Stowers, S. F.; Grood, E. S.; et al. Merging of these components to popliteal tendon inserting on the lateral femoral condyle. Limits of external rotation with a 5-Nm moment for intact specimens and with structures cut. Knee Surg Relat Res. The posterior cruciate ligament (PCL), along with the anterior cruciate ligament, stabilises the knee joint. 20-5B). (From LaPrade, R. F.; Tso, A.; Wentorf, F. A.: Force measurements on the fibular collateral ligament, popliteofibular ligament, and popliteus tendon to applied loads. 20-7) and in the PCL under posterior tibial loads and external tibial torques (Fig.
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