Posterior Ligament Injury

Isolated anterior column compression fractures do not result in neurological injury. Neurological injury in this setting should raise the suspicion of associated disc herniation. With compressions greater than 50 degrees, the middle column acts as a fulcrum and can lead to posterior ligamentous injuries. 

Posterior cruciate ligament injuries (PCL), as in adults, are less common than ACL injuries. In infants and children, it must he remembered that the PCL lies in a more horizontal position than in adults and this must not be confused with injury. Secondary signs of a PCL tear include posterior suhluxation of the tibia, associated tears of the ACL, meniscal tears and avulsion of the tibial insertion (Ross and Chesterman 1986). 

Subluxation of C2 over C3 is associated with inter-vertebral disc injury and also injury to the posterior ligaments and muscles. 

Specific clinical tests in ankle injuries include the anterior drawer and the talar tilt. The anterior drawer maneuver is applied by immobilizing the patient s distal tibia with one hand while applying pressure against the back of the foot with the other (Fig. f6.12a). In complete tears of the anterior and posterior ligaments, and especially of the anterior talofibular ligament, the talus is shifted anteriorly... 

Nakamae et al. also evaluated the biomechanical function of ACL remnants using a navigation system for anteroposterior and rotational knee stability in patients with a complete ACL injury [24]. Patients in groups 1 (bridging between the posterior cruciate ligament and tibia) and 2 (bridging between the intercondylar... 

Avulsion fractures of the posterior inferior iliac spine and the transverse process of the 5 lumbar vertebra are rare but indicative of severe trauma. The former occurs as a result of external rotation of the hemi-pelvis which avulses the sacrospinous ligament at its insertion. The latter injury results when the ilio-lumber ligament is avulsed from the tip of the transverse process of L5 by shearing forces in the vertical plane. These injuries should arouse suspicion of pelvic instability. 

This is the most severe type and results in total sacroiliac joint disruption. Features of the Type 1 and 2 pattern may be present. There is widening of the sacroiliac joint and there is diastasis both posteriorly as well as anteriorly due to the posterior sacroiliac ligament rupture. On clinical examination, the hemi-pelvis is unstable in all directions of force and typically requires operative stabilisation. It is possible for the sacroiliac joint to remain intact but there is fracture of the sacroiliac bone. Complications include bladder rupture, and vascular injury (Figs. 12.8,12.9). 

Fig. 12.7. There is diastasis of the symphysis pubis and widening of the left sacro-iliac joint. Stability was maintained as the posterior sacro-iliac ligaments remain intact. This is an AP Type 2 injury...

This is usually the result of forces transmitted through the axial skeleton from an impact into the head and shoulders through to the lower limbs. There may be symphyseal diastasis, anterior arch fractures or posterior disruption of the sacroiliac joints with cephalic displacement. Vertical injuries are often severe with disruption of all the ligaments plus associated pelvic instability. Radiographs demonstrate ipsilateral or contralateral pubic rami fractures, with disruption of the sacroiliac joint. The major differentiating feature from compression injuries is the cephalic displacement of the pelvis on the side of the impact (Fig. 12.14). 

The dislocation is described according to the direction of tibial displacement relative to the femur. Anterior dislocation is the commonest type, and is associated with disruption of the anterior cruciate ligament, the posterior joint capsule and popliteal artery damage. Posterior dislocation can also be associated with arterial injury. Rotary or posterolateral dislocation is caused by force abduction and internal rotation. On the lateral radiograph, the femoral condyle is in profile but the tibia is rotated posterolaterally and the proximal tibiofibular joint is seen in its entirety. An early complete assessment and documentation of the neurovascular status of the leg distally is vital. Also look for signs of compartment syndrome. 

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