Function of the knee joint

The function of the knee is to enable movement, but also to transfer the weight of the body to the feet during walking. The articular bodies in the knee area are a combination of the convex articular surface of the thigh bone (femur) and the almost flat articular surface of the shin bone (tibia). In this way, the mobility of the knee is increased, but its stability is also significantly reduced. In order to increase the stability of the knee, the correct function of the knee stabilizer is of great importance.

Stabilizers are divided into active and passive. Active stabilizers are muscles that are among the strongest in the human body and at the same time move the joint. Passive stabilizers are: ligaments, the joint capsule and menisci. The most important ligaments of the knee are: medial (internal) and lateral (outer) collateral ligament and anterior and posterior cruciate ligaments.

Posterior cruciate ligament (PCL)

The posterior cruciate ligament (PCL) is one of the 4 key ligaments responsible for knee stability. The PCL is primarily responsible for preventing excessive posterior displacements of the lower leg in relation to the upper leg, i.e. displacement of the tibia (shin bone) in relation to the femur (thigh bone), and is also important in stabilizing the joint during tibia rotation. The anterior and posterior cruciate ligaments inside the knee form an X-shaped (crossing) structure, hence their name. PCL injuries most often occur in traffic accidents and in athletes, i.e. in cases of impact or falling on a bent knee. PCL injuries are less common than anterior cruciate ligament (ACL) injuries and account for 5-20% of all knee ligament injuries.

Anatomy of the knee

• Femur – thigh bone
• Patella – kneecap
• Tibia – shin bone
• Fibula – smaller bone of the lower leg
• Collateral ligaments – tough, elastic connective tissue that surrounds a joint to provide stability
• Cruciate ligaments - the anterior and posterior cruciate ligaments in the knee form the letter X, and ensure rotational stability and prevent excessive movements of the lower leg in relation to the upper leg.
• Menisci – curved cartilaginous parts in the joint that serve as shock absorbers that absorb the load, increase the contact of joint surfaces, etc.
• Muscles – serve to dynamically stabilize the joint

Mechanism of PCL injury

Acute injuries of the posterior cruciate ligament (PCL) are most often the result of a blow to the bent knee (so-called dashboard injury) and can also occur with hyperextension of the knee with rotation or lateral force or with non-contact hyperflexion of the knee with an outstretched foot.

The activities that most often lead to a PCL injury are:

• high impact trauma to the upper leg during car accidents
• fall on a bent (flexed) knee with the foot in plantar flexion (extended foot)
• contact sports

Such situations can lead to ligament injury that can result in a complete rupture (rupture), a partial rupture, or a minor injury (strain) that does not lead to rupture of the ligaments.

PCL injuries often result in other knee injuries, such as injuries to the posterolateral corner, injuries to other knee ligaments, and cartilage and meniscus injuries.

Symptoms of a PCL injury

Early signs:

• "popping sound" at the time of injury
• the knee "gave way" at the time of the injury
• pain and inability to continue activities after the injury
• swelling of the knee

Later signs:

• a feeling of less instability in the knee
• pain in the back of the knee

What to do immediately after an injury?

Immediately after an injury, it is necessary to reduce pain and swelling in the knee using the acronym R.I.C.E. that can be performed in your own home:

• Rest – It is necessary to reduce the load on the knee
• Icing - It is necessary to cool the knee with ice packs every 2 hours for 20 minutes in order to reduce swelling
• Compression – It is necessary to wrap the knee with an elastic or other bandage
• Elevation – In a lying position, it is necessary to place pillows under the injured leg, the leg must be elevated above the heart

When to consult a doctor?

In the event of an injury that has caused a suspicion for a PCL tear, contact your doctor as soon as possible. The PCL is an extremely important structure in the knee, with many functions, especially in people who want to play sports. It is important to ensure timely diagnosis and adequate therapy for each patient. Early intervention is particularly important in order to prevent the progression of the injury in case of a partial rupture and to prevent further damage to the joint. Moreover, even mild pain often causes limping, which, if it persists, significantly changes biomechanics and puts stress on other structures and joints.

Risk factors for PCL injury

• certain sports such as football, basketball, rugby and other sports in which there are frequent collisions, i.e. falling to the knees
• poor general condition
• inadequate sports shoes and equipment
• previous knee injuries

Complications of PCL injury

The integrity of the PCL is critical in maintaining knee stability. An unstable knee is one of the key risk factors in the development of osteoarthritis in later life and a risk factor for other knee injuries such as meniscus tears or cartilage damage.

Diagnostics

Preparation for examination

Before seeing an orthopedic specialist, it is important for the patient to prepare answers to the following questions:

• When did the injury occur?
• What were you doing when the injury occurred?
• Did you hear a "pop" at the time of the injury?
• Was the knee swollen after the injury?
• Have you ever injured your knee before?
• Are your symptoms constant or do they appear occasionally?
• Has your knee ever locked up?
• Do you feel instability in your injured knee?

Orthopedic examination and consultation

Rupture of the posterior cruciate ligament (PCL) is a diagnosis that is made based on knowledge of the mechanism of injury, clinical examination and radiological methods.

The clinical examination includes tests to assess the stability of the knee, tests to detect injuries to other structures such as the meniscus, testing the range of motion and assessing the functionality of the entire knee. The orthopedic specialist will compare the function of the injured and healthy knee and make a decision on possible additional diagnostic procedures.

Radiological diagnostics

In order to confirm the diagnosis of PCL injury in clinically unclear cases, magnetic resonance imaging of the knee is performed. Magnetic resonance (MR) of the knee is a non-invasive examination to obtain quality data on the state of all structures of the knee joint. After determining the type and extent of the injury, a decision on further treatment follows.

Do you need an MRI scan? Book your appointment now because we don't have a waiting list!

Treatment

Treatment of PCL injuries can be surgical or conservative. In case of incomplete ruptures of the PCL, non-operative (conservative) treatment is sufficient, while in the case of complete ruptures of the PCL, it is most often necessary to perform an operation to reconstruct the posterior cruciate ligament.

Conservative treatment

Conservative, i.e. non-operative treatment consists in strengthening the musculature and improving proprioception (sense of positional awareness) of the knee. In the case of an incomplete rupture, it is extremely important to introduce an early immobilization orthosis in order to induce scar healing - this is where the early visit to an orthopedic specialist and precise diagnostics play a key role. In this way, the muscles, by actively stabilizing the knee, try to replace the lack of an important passive stabilizer such as the posterior cruciate ligament - if the damage is not too great. It should be emphasized that by strengthening the musculature that acts on the knee joint, the rotational stability of the knee, which is ensured by the cruciate ligaments, cannot be achieved.

Preoperative rehabilitation

The goal of preoperative rehabilitation is to reduce pain and swelling, while at the same time strengthening the musculature and restoring the range of motion in the injured knee. The results of surgery in a stiff and swollen knee are worse than in patients with full range of motion and no swelling.

In the case of older people with a PCL injury or in individuals who do not intend to play sports or whose work does not require physical activity, this form of physical therapy can be the definitive treatment. By strengthening the muscles, the knee becomes more stable, and it is necessary to maintain the musculature in order to avoid unwanted complications.

Operative treatment

People with a complete rupture of the posterior cruciate ligament develop degenerative joint changes more quickly and are significantly more susceptible to re-injure the knee. For this reason, surgery is recommended in:

• in younger and motivated people
• athletes (professional and recreational)
• in patients with associated injuries to the meniscus or other ligaments
• in patients with a functionally unstable knee

The operation consists of reconstructing the posterior cruciate ligament. The entire operation is performed arthroscopically, under spinal anesthesia or general anesthesia. The course of the operation is monitored on a monitor and, if desired, the patient can watch the operation and communicate with the operator. During the operation, the operator removes the damaged ligament, while a part of the injured person's tissue (autograft) is used for reconstruction. Most often, a part of the tendons of the muscles of the back part of the upper leg (tendons of the semitendinosus and gracilis muscles) or the central part of the patellar ligament of the same knee is used. Such a graft can be fixed with a completely resorbable material that slowly resorbs over time, i.e. melts inside the body after the graft has healed.

Book an appointment for an examination and find out all the detailed information about the mentioned procedure.

Postoperative rehabilitation

After the surgery, the patient is transferred to the department where physical therapy is started. Together with the physiotherapist, the patient can walk on crutches and behave with the operated leg. The patient usually spends one night in the hospital after the procedure and is discharged from the hospital in the morning after dressing the surgical wounds and physical therapy.

Risks of surgery

As with any surgical procedure, there are risks with PCL reconstruction such as bleeding or infection of the surgical wound. Other risks with PCL reconstruction can be:

• knee pain or stiffness
• poor healing of the graft ("new" ligament)
• rupture of the graft after returning to sports
• postoperative rehabilitation

It takes several months for the graft to fully fuse, and before that time no greater load on the knee is allowed. Correct postoperative rehabilitation is complex and extremely important for the complete recovery of stability and function of the knee and generally lasts 5 to 6 months per operation. Before returning to normal physical activities, it is necessary to make several control examinations in which the current function of the knee joint and the "new" ligament will be examined. After the physical therapy, the athlete needs good kinesiotherapy in order to balance the musculature, increase stability and reduce the possibility of re-injury of the PCL.