Medial Tibial Plateau

Hashemi J, Chandrashekar N, Mansouri H, Gill B, Slauterbeck JR, Schutt RC Jr, Dabezies E, Beynnon BD (2010) Shallow medial tibial plateau and steep medial and lateral tibial slopes new risk factors for anterior cruciate ligament injuries. Am J Sports Med 38(l) 54—62... 

Fig. 14.8. Types of tibial plateau fractures I, split fracture of the lateral tibial condyle II, split fracture with associated depression III, depressed fracture of the lateral tibial plateau IV, fracture of the medial tibial plateau V, bicondylar fracture (can be T or Y shaped) VI, bicondylar fracture with metaphyseal/diaphyseal association...

The femorotibial joint consists of two compartments medial and lateral. The medial compartment is composed of the larger medial condyle and the concave superior aspect of the medial tibial plateau and has a wider anteroposterior diameter compared with the lateral one. The lateral compartment is formed by the smaller lateral condyle and the flat or convex articular surface of the lateral tibial plateau. The medial compartment gives stability to... 

The anatomy of the ACL in relation to the knee joint architecture. Proximally, it is attached to the posterior aspect of the medial surface of the lateral femoral condyle, passing in front of the PCL and attaching distally on the tibial plateau. 

When an ACL is ruptured, the axis of rotation shifts more medially and the tibial rotation causes a coupled anterior tibial translation, magnifying the movements of the tibial plateau. The primary insult is thus to the lateral compartment, mainly the posterior aspect, and injury to the medial compartment occurs secondarily. The lateral compartment is most frequently injured mainly because it can sublux more easily. 

Joint compressive force equivalent to body weight results in increases in ACL strain [3, 7] and ACL force [13], because anterior force is generated in association with joint compressive force due to the posteroinferior slope of the tibial plateau [11]. As a result, the neutral position of the tibia shifted anteriorly in response to joint compressive loading [7, 31]. Therefore, the anterior laxity, defined as a translation of the knee from the neutral position in response to an externally applied anterior force, decreases under the application of compressive loading. It is reported that anterior tibial subluxation of ACL-deficient knees is more significant in lateral side than in medial side in response to weight bearing [18]. 

Fig. 10.6 The proposed noncontact ACL injury mechanism, (a) An unloaded knee, (b) When valgus loading is applied, the MCL becomes taut and lateral compression occurs, (c) This compressive load causes a lateral femoral posterior displacement, probably due to the posterior slope of lateral tibial plateau, and the tibia translates anteriorly and rotates internally, resulting in ACL rupture, (d) After the ACL is tom, the primary restraint to anterior translation of the tibia is gone. This causes the medial femoral condyle to also be displaced posteriorly, resulting in external rotation of the tibia...

Several studies have attempted to objectively evaluate the Lachman test by subjective assessment. Lerat et al. [22] examined the anterior/posterior displacement in 563 normal knees and 487 ACL-deficient knees using stress radiography with an anterior load of 9 kg at 20° knee flexion angle, which mimicked the Lachman test. They used the posterior femoral condyle and posterior tibial plateau as reference points on radiography and measured the anterior/posterior translation in both the medial and lateral compartments. Logan et al. [23] investigated the Lachman test... 

Furthermore, ACL tears are often associated with injuries to additional structures, such as the medial collateral ligament, meniscal tears, and Segond fracmres, which are capsular avulsion fractures of the lateral tibial plateau, found in 6-13 % of ACL ruptures [27] (Fig. 12.4C). 

Width and depth of the tibial plateau (width in A-P view in % from medial to lateral, depth in lateral view in % from anterior to posterior). 

In the knee, the medial and lateral condyles of the femur articulate with tibial plateau (Fig. 14.1). The... 

---