Chapter 32

### Introduction

As for the rupture there is no missing it. I didn’t so much hear it but the “pop” like a thick elastic giving way reverberated through [my] body. It’s distinct—it’s clear what’s happened.

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For many sportspeople, the most fearful injury is that of the acute knee—it can spell the end of a professional career. Even for recreational sportspeople, an acute knee injury may be the catalyst for early arthritis. Acute knee injuries are common in all sports that require twisting movements and sudden changes of direction, especially the various types of football, basketball, netball, and alpine skiing.

### Functional anatomy

The knee joint can be divided into two parts—the tibiofemoral joint with its associated collateral ligaments, cruciate ligaments, and menisci; and the patellofemoral joint, which obtains stability from the medial and lateral retinaculum, and the large extensor mechanism tendons (quadriceps and patellar tendons) which encase the patella distally before its insertion on the proximal tibia. Most commonly we refer to the tibiofemoral joint as the knee joint. The anatomy of the knee joint is shown in Figure 32.1.

###### Figure 32.1

Anatomy of the knee joint

(a) The knee joint (anterior view)

(b) The knee joint (posterior view)

The two cruciate (“cross”) ligaments, anterior and posterior, are often referred to as the “crucial” ligaments, because of their importance in providing knee stability. They are named anterior and posterior in relation to their attachment to the tibia. The anterior cruciate ligament (ACL) prevents forward movement of the tibia in relation to the femur, and controls rotational movement of the tibia under the femur. The posterior cruciate ligament (PCL) prevents the femur from sliding forward off the tibial plateau.

The ACL is essential for control in pivoting movements. If the ACL is not functional, the tibia may rotate under the femur in an anterolateral direction, such as when a sportsperson attempts to land from a jump, pivot, or stop suddenly. The PCL stabilizes the body (femur) above the tibia. In its absence, the femur wants to shift forward on the tibia. This shift forward is accentuated when one tries to run down an incline or descend stairs.

The two collateral ligaments—the medial and the lateral—provide medial and lateral stability to the knee joint. The superficial medial collateral ligament (MCL) is extra-capsular. The deep layer, or coronary ligament, attaches to the joint margins and has an attachment from its deep layer to the medial meniscus. The MCL prevents excessive medial opening (i.e. valgus) of the tibiofemoral joint.

The lateral collateral ligament (LCL) is a narrow strong cord; it has no attachment to the lateral meniscus. It prevents lateral opening of the ...

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