Posterior cruciate ligament injuries: causes, symptoms, diagnosis, treatment

Damage of the posterior cruciate ligament (ZKS) is one of the most serious injuries of the capsular-ligament apparatus of the knee joint. They are encountered much less often than ruptures of the anterior cruciate ligament (PKC), they account for 3-20% of all knee joint injuries.

Tears of the posterior cruciate ligament can be isolated or combined with damage to other ligaments and structures of the knee joint (for example, meniscuses, anterior cruciate ligament, collateral ligaments, joint capsule, popliteal tendon, arched ligament). Isolated ruptures of the posterior cruciate ligament account for 40% of all her injuries and 3.3-6.5% of all knee joint injuries.

[1], [2]

What causes damage to the posterior cruciate ligament?

Several mechanisms of damage to the posterior cruciate ligament have been described in the literature. The most common - direct mechanism of injury - a blow on the front surface of the proximal third of the tibia, bent at the knee joint. Such a mechanism is most often encountered in road accidents (impact on the dashboard). Damage of the posterior cruciate ligament began to occur more often during sports, especially in such kinds of sports as football, rugby, hockey, downhill skiing, wrestling. A more infrequent mechanism of damage to the posterior cruciate ligament is the indirect mechanism of trauma - a fall on the knee joint area and a violent overtraining of the tibia in the joint. This leads to a rupture of the posterior section of the joint capsule and the posterior cruciate ligament. Simultaneous damage of the posterior cruciate ligament and anterior cruciate ligament usually occurs when the force of the trauma agent is applied in several planes. This is the rotational moment for a fixed foot with simultaneous application of force from the outside to the inside and from the front to the rear. Trauma of this nature is possible when falling from a height and car accidents. Knowledge and understanding of the mechanisms of damage to the posterior cruciate ligament enable timely diagnosis of the rupture of the posterior cruciate ligament.

Symptoms of a posterior cruciate ligament injury

Because of the difficulty of differentiating the anterior cruciate ligament and the posterior cruciate ligament, when diagnosing the damage, the posterior cruciate ligament is often not diagnosed, which leads to the development of posterior instability and secondary changes in the knee joint. In the absence of treatment, the deforming arthrosis of the knee joint progresses in 8-36% of cases.

The ruptures of the posterior cruciate ligament can be combined with damage to the posterior and / or posterior capsular-ligament structures of the knee joint, depending on the mechanism of the injury.

In the literature there are great disagreements about the treatment of back instability of the knee joint. Some authors try to restore the posterior cruciate ligament at any cost. Others, taking into account the technical difficulties associated with the restoration of the central axis, perform the plastic of active and passive structures of the knee joint, providing a stable position in the lead or lead, as well as controlled internal or external rotation of the shin. Methods of reconstruction include plastic with local tissues, plastic with the use of synthetic tissues, single-channel and two-channel methods, open and arthroscopic methods.

All existing methods and methods of surgical treatment of injuries of the posterior cruciate ligament of the knee joint can be divided into intraarticular and extraarticular. Extra-articular surgery is based on the restriction of the posterior subluxation of the shin. The meaning of extra-articulate stabilization lies in the location of the tendon structures in front of the knee joint rotation center, which creates an obstacle to the posterior subluxation of the tibia when moving in the joint. Currently, extra-articular reconstructions, as an isolated method of stabilization, are rarely used, more often they are an addition to intra-articular stabilization. Extra-articulate stabilization is more expedient to spend at considerable degrees of a deforming arthrosis of a knee joint.

To assess the condition of the knee joint, classical methods of examination are used: anamnesis, elucidation of the mechanism of injury, examination, palpation, measurement of the joint circumference and periarticular segments of the lower extremity to detect muscle hypotrophy, the amplitude of passive and active movements, special tests that detect meniscus lesions, ligamentous structures, instability etc. Of special additional methods of research, ultrasound, MRI, X-ray review, functional radiographs with exercise are used.

Complaints

Patients' complaints are varied and do not always indicate a posterior instability of the knee joint. Patients can complain about:

• discomfort in the knee joint with a semi-bent position of the limb, while climbing and descending the stairs, as well as walking for long distances;
• pain under the patella, resulting from the deflection of the tibia posteriorly;
• instability in the joint when walking on uneven terrain;
• pain in the internal part of the joint, which is associated with degenerative changes in the joint.

Examination and physical examination

When looking at, pay attention to the nature of the gait, the presence of lameness. For all kinds of instability of the knee joint, attention is paid to the axis of the lower extremity (varus or valgus deviation, recurrence). The examination is continued in the patient's lying position for comparison with a healthy limb.

Chronic back instability is much easier to diagnose than an acute rupture of the posterior cruciate ligament. The most frequent complaint of patients in case of acute damage is pain in the knee joint. The presence of significant effusion in the joint is rarely observed, since the blood due to rupture of the posterior part of the capsule (the joint tightness is broken) can spread along the interfascial spaces of the shin. Most patients with ruptures of the posterior cruciate ligament do not report a flick at the time of injury, which is often heard when the anterior cruciate ligament ruptures. Soreness and hematoma in the popliteal fossa should alert the clinical doctor with regard to rupturing the posterior cruciate ligament. In this case, a detailed explanation of the mechanism of the trauma may be helpful in establishing the correct diagnosis (for example, a direct impact of the front of the shin on the dashboard in car accidents is the most characteristic mechanism of injury). Patients with a rupture of the posterior cruciate ligament can move independently with full load on the limb, but the shin is slightly bent at the knee joint, the victim avoids full extension of the shin and its external rotation. Particular attention during examination should be paid to bruises and abrasions of the skin on the front surface of the knee due to a direct stroke, the presence of bruising in the popliteal fossa. It is important to remember that the absence of effusion in the joint does not exclude a serious injury to the capsular-ligament structures of the knee joint.

If the damage of the posterior cruciate ligament is combined with damage to other ligaments of the knee joint, the effusion in the joint will be much greater. With multiple ligament ruptures, there is a risk of damage to the neurovascular structures. Especially often this happens when the shin is dislocated in the knee joint. Approximately 50% of the shank dislocations recover spontaneously during the trauma, so during the medical examination they are not detected, which leads to incorrect diagnosis and inadequate treatment. Therefore, in all cases careful monitoring of blood circulation and sensitivity of the lower limb is necessary. In doubtful cases, you can perform a Doppler scan of the vessels of the lower limb and EMG.

Tests used to diagnose damage to the posterior cruciate ligament

The first step in the clinical examination of a damaged knee joint is the differentiation between the pathological anterior and posterior shank displacement. Normally at 90 ° flexion of the tibial plateau protrudes anteriorly from the condyles of the thigh by about 10 mm. With posterior instability, the tibia is displaced posteriorly under gravity. The symptom of the anterior "drawer" revealed from this position will be false positive, which can lead to incorrect treatment of the pathology and incorrect diagnosis.

• The test of the posterior "drawer" when bending at the knee joint to a 90 ° angle is the most accurate test for diagnosing a rupture of the posterior cruciate ligament. The degree of displacement is determined by the change in the distance between the anterior surface of the medial plateau of the tibia and the medial condyle of the thigh. Normally the plateau is located 1 cm in front of the condyles of the thigh. The posterior "drawer" is classified as grade I (+) with 3-5 mm of tibial displacement, with the tibial plateau located in front of the condyles of the thigh; II degree (++) - at 6-10 mm, the tibial plateau is at the level of the condyles of the thigh, grade III (+++) - at 11 mm or more, the plateau of the tibia is behind the femoral condyles.

The degree of displacement in the sagittal direction is evaluated by flexing the knee joint at an angle of 30 °. A slight increase in displacement at 30 °, and not at 90 ° flexion, may indicate damage to the back of the non-lateral complex (ZLK). The test of the rear drawer is difficult to perform in an acute period due to swelling and restriction of flexion of the knee joint. In case of acute damage, you can use the back Lachman test.

• Reverse Lachman-test (back Lachman-test). As with the normal Lachman test, the knee joint is held in the same way at 30 ° flexion, the tibia is displaced posteriorly. The displacement of the tibia posterior to the hip indicates a rupture of the posterior cruciate ligament.
• Trillat test - back shift of the tibia when flexing in the knee joint to an angle of 20 °.
• The test of the posterior trough (sag, Godfrey test) is a decrease in the convexity of the tuberosity of the lumbar bone in comparison with the healthy limb. To perform this test, the patient lies on his back with bent knee and hip joints to a 90 ° angle. The doctor holds the foot of the patient by the toes of the foot. Under the action of gravity, a shift of the tibia occurs.
• Active test of the quadriceps femoris - when bending at the knee joint to a 90 ° angle and a fixed foot during the tension of the quadriceps muscle of the thigh, the shin extends from the position of the posterior subluxation (reduction).
• Test of active elimination of posterior subluxation. The studied limb is bent at the knee joint to an angle of 15 °, with an active raising of the limb 2-3 cm from the surface, the posterior subluxation of the shank in the knee joint is eliminated.
• Test of passive elimination (reduction) of the posterior subluxation of the shin. Similar to the previous test, the only difference being that when the lower limb is raised behind the heel, the proximal section of the sulcus is displaced anteriorly.
• Dynamic test of the rear change of the fulcrum. Flexion in the hip joint 30 ° at small bending angles in the knee joint. With full extension, the posterior subluxation of the tibia is eliminated with a click.
• Symptom of the rear "drawer" in the position of the patient lying on his stomach at 90 ° flexion in the knee joint. With a passive posterior displacement of the shin, its posterior subluxation occurs. The foot is shifted towards the combined injury.
• Test tibia external rotation is performed in the prone position of the patient at 30 ° and 90 ^e flexion of the knee. Isolated damage of the posterolateral structures gives the maximum increase in external rotation at 30 °, and the combined injuries of the posterior cruciate ligament and ZLK increase the degree of excessive external rotation at 90 ^e flexion. The degree of rotation is measured by the angle formed by the medial border of the shin and the axis of the femur. Comparison with the contralateral side is mandatory. The difference of more than 10 ^{D is} considered pathological.

Since the injuries of the posterior cruciate ligament are rarely isolated, all patients need to conduct a clinical examination of other ligaments of the knee joint. Abdominal and adduction tests are used to identify the inconsistency of the peroneal and lumbar collateral ligaments. The study is carried out in the position of complete extension of the tibia and at 30 ° flexion in the knee joint. By the degree of abduction of the tibia in the sagittal plane, it is possible to judge the degree of damage to the capsular-ligament structures. The increase in varus deviation at 30 ° flexion in the knee joint indicates damage to the peroneal collateral ligament. An additional slight increase in varus deviation with full extension is compatible with damage to both of these structures. If there is a large degree of varus deviation with full extension, then there may be a combination of damage to ZLK, ZKS and PKS.

Diagnosis of posterior cruciate ligament injury

Radiographic examination

Radiography is the most reliable method of examination of the knee joint. Evaluation of radiographic images is very important. Calcifications and osteophytes in the posterior intercondylar region not only indicate chronic injury of the posterior cruciate ligament, but may also interfere with surgical intervention. Degenerative changes are often present in the medial and femoral-patellar articulation. To determine the posterior displacement of the tibia relative to the femur, functional radiographs with a load are performed. Various adjustments are used to shift the lower leg. The lower limb is placed on a special pedestal, with an angle of flexion in the knee joint to 90 °, the foot is fixed, the shank is shifted backwards by means of special rods to the maximum position.

Magnetic resonance imaging

The most informative of non-invasive instrumental methods of investigation is magnetic resonance imaging (MRI), which allows visualizing both bone and soft tissue structures of the knee joint.

The accuracy of diagnosis with MRI, according to different authors, is 78-82%. With MRI, the rupture of the posterior cruciate ligament is determined better than the anterior cruciate ligament. The anterior cruciate ligament is brighter than the posterior cruciate ligament. The fibers of the posterior cruciate ligament are parallel, and the fibers of the anterior cruciate ligament are twisted. The lack of continuity of the fibers or their chaotic orientation indicate a ligament rupture. The intact posterior cruciate ligament is defined from behind as a convex, homogeneous structure of low signal intensity. A break increases the intensity of the signal. Bleeding zones and edema (with acute rupture) look like limited areas of increased signal intensity. MRI is 100% informative with complete ruptures of the posterior cruciate ligament. Partial ruptures and damage during ligament are more difficult to recognize. With the extension of the lower leg, the posterior cruciate ligament has a slight posterior bias in the sagittal plane.

Often next to the posterior cruciate ligament is a fibrous cord that connects the horn of the external meniscus with the hip limb. This is the anterior or posterior meniscofemoral ligament (Wrisberg or Hemphrey).

MPT can be used to assess the condition of meniscuses, articular surfaces and knee joints that are not visible on conventional radiographs and can not be distinguished by computed tomography. However, a standard MRI is usually not informative for assessing CLD.

Ultrasonography

Ultrasound examination allows to study the state of the soft tissues of the knee joint, the surface of bone and cartilage, and also to reduce the echogenicity of the edema of tissues, the accumulation of fluid in the joint cavity or periarticular formations.

The most accessible and convenient place for the study of cruciate ligaments is the popliteal fossa. This is the attachment site of the distal sections of the ligament. Both cruciate ligaments on sonograms are visible as hypoechoic bands in the sagittal section. The anterior cruciate ligament is best examined transversely in the popliteal fossa. A comparative study of the contralateral joint is mandatory.

Complete ligament damage is detected as a hypo or anechogenous formation at the attachment site to the femoral or tibia. Partial or total ligament damage appears as a global thickening of the ligament.

Ultrasound can be used to detect damage to the cruciate ligaments, knee joint meniscuses, collateral ligaments, soft tissue structures surrounding the knee joint.

[3], [4]

Treatment of posterior cruciate ligament injury

In the acute period of trauma (up to 2 weeks) with the detachment of the posterior cruciate ligament from the internal condyle of the thigh, the stump of the ligament can be re-established to the place of anatomical attachment using arthroscopic technique.

In the case of development of chronic back instability of the knee joint with a compensated form, conservative treatment is carried out, including therapeutic gymnastics aimed at strengthening the muscles that prevent the pathological posterior shank displacement, massage, electrostimulation of the quadriceps muscle of the thigh.

The subcompensated or decompensated back instability of the knee joint can only be eliminated promptly. For this purpose, intra-articular autoplastic or alloplastic (for example, lavsanoplastic) and extra-articular (aimed at activating the activity of the periarticular muscles) are performed by stabilizing operations.

In the department of athletic and ballet injury of FGU 1 DITO with damage to the posterior cruciate ligament, arthroscopic intra-articular stabilizing operations using a single-bundle or two-beam autograft from the patellar ligament are performed.

Rear static stabilization using a single-beam autograft from the patellar ligament

This type of surgery is used in patients with injuries of the posterior cruciate ligament and meniscus, one of the collateral ligaments, and also in the case of anteroposterior instability (i.e., simultaneous restoration of the anterior cruciate ligament and posterior cruciate ligament).

At the first stage, arthroscopic diagnosis of the knee cavity is performed, all necessary manipulations are performed (for example, meniscus resection, anterior cruciate ligament dissection, treatment of chondromalation and cartilage defects, removal of free intraarticular bodies), and grafts from the patellar ligament are taken. From the additional posterior-medial access, examine the posterior edge of the tibia and release it from the Scar tissue. By analogy with the location of the native posterior cruciate ligament, the location of the exit of the intraosseous canal is determined - 1-1.5 cm below the posterior edge of the tibia in its middle. In the calculated location for the tibial canal, the needle is guided through a stereoscopic system. To determine the correct position of the needle, intraoperative radiographs in the lateral projection are performed.

A cannulated drill is introduced along the guide wire, the size of which depends on the size of the bone graft blocks. To avoid damage to the neurovascular structures, a special defender is used.

The position of the shin at this moment is the maximum extension anteriorly.

Next, examine the internal condyle of the femur and choose a place for the intraosseous canal, a reference point is the natural arrangement of the posterior cruciate ligament. In the calculated place, guide the needle. When performing the femoral canal, it is necessary to maintain a constant bending angle in the knee joint (110-120 °) for correct positioning and facilitating the boring of the canal, as well as reducing the likelihood of damage to cartilage on the lateral condyle of the thigh. A drill is inserted on the needle and the intraosseous canal is drilled.

The next stage of the operation is to perform a transplant into the cavity of the knee joint. The transplant is fixed with an interference titanium or biorassable screw. During the insertion of the screw, it is necessary to tighten the transplant as much as possible to avoid winding it around the screw.

The transplant is then fixed in the tibial canal with an interferential screw when the knee is bent at the knee joint to 90 ° and maximally withdrawn from the position of the posterior subluxation. After fixing the transplant on the operating table, control radiographs in the direct and lateral projections are performed. After the operation is completed, the limb is fixed with the tire. The angle of flexion of the shank in the knee joint in the tire is 20 °.

Rear static stabilization of the knee joint using a two-beam graft

Indication for this operation is considered total instability of the knee (damage to the posterior cruciate ligament, anterior cruciate ligament and collateral ligaments). The use of a two-beam graft for this type of instability can sufficiently eliminate the shin rotation.

At the first stage, arthroscopic diagnosis of the knee joint and necessary surgical manipulations for concomitant intraarticular pathology are performed similarly. An autograft of 13 mm width is taken from the patellar ligament with two bone blocks from the lower pole of the patella and tuberosity of the tibia. The tendon part of the transplant and one bone block are dissected into two parts.

The next stage of the operation (the allocation of the attachment of the posterior cruciate ligament to the tibia, the formation of the tibial canal) is carried out in exactly the same way as when using a single-beam graft. Then proceed to the implementation of the femoral canals. The center of the canal for the anterolateral beam is located at a distance of 7 mm from the edge of the articular cartilage and 7 mm from the intercondylar fossa, and the center of the channel for the median posterior beam is 4 mm from the edge of the articular cartilage and 15 mm from the intercondylar fossa roof. In the planned points alternately guide the spokes, drill the channels, first zadnemedialny, and then anterolateral. Next, a graft is performed. The first is carried out and the posteromedial fascicle is fixed. Then, with the full extension of the tibia in the knee joint, the distal end of the transplant is fixed in the tibial canal. After this, the shin in the knee joint is bent to 90 °, the anterior medial bundle is stretched and, at the maximum excision of the tibia from the position of the posterior subluxation, is fixed.

Arthroscopic treatment of popliteal cysts (Baker cysts)

Very frequent consequences of intraarticular injuries and diseases of the knee joint, which significantly violate its functions and the tolerance of physical exertion, are cysts formed in the popliteal region. According to different authors, the probability of popliteal cysts in various pathological processes in the knee joint is from 4 to 20%.

Popliteal cysts, or Baker's cysts, are not true cysts. These are volumetric formations in the popliteal fossa containing a fluid that have a synovial membrane and are usually associated with the knee joint.

The extensive introduction in recent years of arthroscopic techniques for the diagnosis and treatment of injuries and diseases of the knee joint, as well as information on the anatomical and functional features of the joint, obtained during endoscopic examination of the knee joint, formed the basis for a new direction in the treatment of poplite cysts. The use of arthroscopy allowed to prove that cysts of the popliteal region develop as secondary pathological changes against the background of injuries of intraarticular structures and degenerative diseases of the knee joint.

Popliteal cysts come from mucous bags of the knee joint - closed cavities, in some cases isolated, in others having a communication with the joint cavity or with an adjacent cyst. The substrate for the appearance of these cysts is the stretching of the popliteal region, communicating with the cavity of the knee joint (in particular, the bag located between the tendons of the medial head of the gastrocnemius and semimembranous muscle). An increase in the volume of fluid in the cavity of the knee joint leads to the accumulation of fluid in the bag and the occurrence of the popliteal cyst.

Carrying out arthroscopy allows to reveal a popliteal cyst. It has the appearance of a capsule defect in the posterior part of the knee joint, it is localized more often in its medial part at or above the joint gap, usually has a rounded shape and sizes from 3 to 10 mm, rarely - the appearance of a slit-shaped capsule defect up to 12-15 mm in length.

Restoration of normal interrelations of intraarticular structures in the knee joint helps cure the cyst. In order to prevent the recurrence of cysts and to achieve a more reliable result of treatment when an anastomosis of the cyst is detected, in addition to sanation, anasthenia cysts are coagulated.