The stability of the knee joint, as one of the main elements of the normal functioning of the musculoskeletal system, is ensured by the capsular ligamentous apparatus. Partial or complete ruptures of the knee ligaments over time lead to instability of the joint, involving other, previously undamaged structures in the pathological process. The ligaments of the joint can rupture and tear off from the bone attachment with excessive movements and deviations of the tibia to the sides, with hyperextension of the knee and rotation of the femur along the internal axis.
ANATOMY
Ligaments are strong structures of connective tissue that connect bones to each other. The knee joint is strengthened by two collateral (side) ligaments, which prevent excessive abduction and adduction of the tibia. The medial collateral ligament is located on the inner surface of the knee joint, that is, on the side facing the other knee joint. The lateral collateral ligament is located on the outside of the knee joint. Excessive stretching of these ligaments as a result of injury can result in their rupture. The tear line can be located anywhere in the ligament, both in the center of the ligament and at the place where it attaches to the bones. With significant trauma, combined damage to the collateral and intra-articular ligaments of the knee joint can occur.
Most often in clinical practice, a combination of rupture of the medial collateral and anterior cruciate ligaments is observed. The anterior cruciate ligament is located inside the knee joint, in its central part, and its function is to limit the anterior movement of the tibia relative to the femur. The incidence of medial collateral ligament rupture is higher than that of the lateral collateral ligament, but the likelihood of developing knee instability is higher with the latter type of traumatic injury. One reason for the high incidence of joint instability with lateral collateral ligament rupture is that the medial portion of the tibial plateau has a deeper depression. On the contrary, on the side of the lateral collateral ligament, the tibial plateau has a flat surface, and therefore the amplitude of bone movement in this part of the joint is higher.
The force that causes a rupture of the collateral ligament inevitably leads to damage to the soft tissue near the knee joint. As a result, bruising occurs and traumatic swelling of the joint area develops. Some patients experience damage to intra-articular blood vessels, which causes hemarthrosis - accumulation of blood in the joint cavity. The injury causes pain and stiffness in the joint. Many patients, already in the “acute” period of injury, are worried about instability of the joint: the leg twists if the patient transfers body weight to it. Chronic instability of the knee joint as a result of damage to the collateral ligaments is a fairly common pathology. Instability can occur either as a result of complete disruption of the integrity of the collateral ligament, or due to insufficient function of the ligament due to its incomplete or improper consolidation.
Brief Anatomy of the Knee Joint
The joint is formed by 3 bones: the distal epiphysis of the femur, the proximal epiphysis of the tibia, between which are the lateral and medial menisci, and the patella. There are two groups of ligaments:
1. Extracapsular (located outside the joint cavity):
- tibial or internal collateral;
- fibular or external collateral;
- patellar ligament.
2. Intracapsular (located inside the joint cavity):
- anterior cruciate;
- posterior cruciate.
DIAGNOSTICS
A physical examination (examination, palpation, study of lower limb mobility) allows the doctor to make a presumptive diagnosis of collateral ligament rupture. Physical examination is a valuable diagnostic method, allowing the identification of intra-articular or periarticular ligament rupture in most patients. In the acute period of injury, physical examination is difficult due to severe pain and swelling of the knee joint. In these cases, rest for 5-7 days is prescribed for the injured limb, analgesic medications, and cold (ice packs) on the area of the damaged joint. During this time, the pain subsides and the swelling decreases, which makes it possible to conduct a full physical examination of the knee joint.
X-rays of the knee joint are performed to exclude possible bone fractures due to injury to the knee joint. In order to diagnose a collateral ligament rupture in the presence of symptoms of instability, functional (stress) radiography is necessary. In this case, an x-ray of the joint is taken when the radiologist's assistant moves the patient's lower leg to the side (medially or laterally). The diagnosis is confirmed if widening of the joint space is noted on the side of the collateral ligament rupture. If combined damage to periarticular and intraarticular ligaments, menisci or articular cartilage is suspected, magnetic resonance imaging is indicated. In this case, the image of the knee joint takes the form of a series of longitudinal and transverse sections, which are obtained as a result of digital processing of signals obtained using electromagnetic waves. Magnetic resonance imaging is especially the “gold” standard for diagnosing damage to the soft tissue structures of the knee joint (cartilage, ligaments, tendons). This completely safe and painless research method can be especially useful if the doctor has doubts about the presence of damage to the structures of the knee joint.
Basic principles for diagnosing knee ligament ruptures:
Modern diagnostic equipment and the clinical experience of traumatologists at the Sourasky Medical Center make it possible to make the correct diagnosis and identify the exact location of the rupture without much difficulty.
- Inspection and palpation of the knee joints.
- X-rays of the knee joint (to exclude fractures of the tibia or femur).
- Ultrasound scan of the joint (to confirm hemarthrosis).
- Magnetic resonance imaging (to exclude meniscal tears).
- Diagnostic arthroscopy (to identify ruptures of intra-articular cruciate ligaments, with the possibility of surgical suturing).
TREATMENT
An isolated tear of the lateral or medial collateral ligament rarely requires reconstructive surgery. In these cases, conservative therapy is carried out, which consists of fixing the lower limb extended at the knee joint using a brace or plaster cast. However, many traumatologists prefer not to use external immobilization of the knee joint for an isolated rupture of the medial collateral ligament. Although there is an opposite point of view: external immobilization means should be used for any injury to the knee joint, accompanied by pain and symptoms of instability. Initial treatment for a collateral ligament tear is aimed at reducing pain and traumatic swelling. To do this, it is necessary to rest the injured limb and apply ice packs to the knee joint area. In case of significant injury, it is recommended to take anti-inflammatory drugs (diclofenac, aspirin, ketonal, etc.). When walking, you must use crutches until the lameness disappears.
To reduce pain in the acute period, the use of transcutaneous electrical nerve stimulation (TENS) may be indicated. After severe pain subsides and swelling decreases, physical therapy is added to the complex of conservative therapy. The purpose of physical therapy is to restore the normal range of motion in the damaged joint and restore the strength of the muscles of the limb (especially the quadriceps muscle located in the anterior region of the thigh). It has now been shown that early administration of physical therapy leads to a more rapid and complete restoration of knee joint function and a reduction in the overall duration of the rehabilitation period. If, after restoring muscle strength and joint function, the patient still has symptoms of instability, the patient must use external immobilization devices (braces) during physical activity. In some cases, the surgeon may offer you surgical treatment.
Surgical treatment is usually indicated for combined damage to the collateral ligament and other structures of the knee joint. Some surgeons believe that with a combined rupture of the medial collateral and anterior cruciate ligaments, surgery is necessary to restore the function of both ligaments. Other experts disagree with this opinion. They propose to perform anterior cruciate ligament replacement after a course of conservative treatment aimed at restoring the integrity of the collateral ligament. Time will tell which approach is optimal. During reconstructive surgery, a skin incision is made in the area of projection of the torn collateral ligament. If the ligament is torn off in the area of its attachment to the bone, then the ligament is fixed using metal fixators or strong synthetic threads. In case of a median rupture of the collateral ligament, the ends of the ligament are sutured to each other. With “old” ruptures, suturing of the collateral ligament is in many cases not possible due to the appearance of scar changes in the torn ligament. To eliminate instability of the knee joint in these cases, the torn collateral ligament is replaced with an autograft. What it is? An autograft is a piece of ligament or tendon that is taken from another location from a patient during surgery. In most cases, the tendon of the semitendinosus muscle, one of the muscles of the posterior thigh, is used as a graft. Recent studies have shown that harvesting of the semitendinosus tendon does not result in decreased lower extremity strength due to compensatory hypertrophy of other thigh muscles. The ends of the autograft are attached to the bone using metal screws or strong synthetic threads.
General information about damage
Anterior cruciate ligament reconstruction is the most common knee ligament procedure. The remaining ligaments of this section of the lower extremities are much less likely to be injured and rarely require surgical intervention. For example, the ACL is injured approximately 15 times more often than the PCL. Some sources even indicate that it is 30 times. The explanation for this is the specific anatomical structure of the ACL: it is longer and thicker than the posterior connective tissue cord.
Image of gaps.
Violation of integrity, namely its ruptures, mainly occurs due to sports injuries, as well as as a result of falls with legs fixed parallel to the surface (skier injuries), unsuccessful landings after a jump on straightened legs. Damage to the ligamentous bundles can also occur due to a strong blow to the back of the knee, twisting and sudden movements, for example, during a sharp turn or sudden braking while running. It is possible to recognize that a particular ligament has been damaged only through certain diagnostic tools:
- MRI (CT and X-ray are less effective);
- diagnostic arthroscopy;
- special clinical tests, for example, “anterior drawer”, Lachman, Pivot Shift test, etc.
What does the injury look like on an MRI?
As for the symptoms that may indicate a similar problem, they are pronounced, especially in the early period. The clinical picture of a complete rupture is as follows:
- cracking immediately at the moment of rupture;
- acute severe pain in the knee;
- the painful syndrome intensifies with any attempt to move the leg;
- the lower leg is shifted forward;
- rapid increase in swelling;
- hemorrhage in the joint;
- dysfunction of supporting ability.
The above signs are inherent in diseases of other components of this joint, so to confirm it you will definitely need to undergo an examination by a traumatologist and diagnostic procedures. Depending on the severity of the rupture (micro rupture, partial or complete), the doctor will select adequate treatment tactics. For non-serious injuries, conservative therapy is used; complex cases require surgical treatment.
Due to the destructuring of the frontal cruciate ligament, the biomechanics of the joint as a whole suffers: joint instability and pathological displacement of the articular surfaces relative to each other occur. This adversely affects the cartilaginous coverings of interacting bone units - they begin to suffer from irrational loads during movements. If the ligamentous apparatus is not corrected in time, gonarthrosis may develop, which leads to serious degeneration of not only the articular cartilage, but also the menisci.
Torn fibers are visible through the arthroscope.
Attention! A completely torn anterior cruciate ligament of the knee joint without plastic surgery is not able to unite and heal on its own. Therefore, to restore its functionality, if the defect is truly serious, an arthroscopic procedure is prescribed to restore the integrity of the ACL.
REHABILITATION
Small tears of the medial or lateral collateral ligaments heal within 4-6 weeks. For more serious ligament ruptures, the rehabilitation period is extended to 2 months. A complete tear of the collateral ligament takes at least 3 months to heal, although surgery is sometimes required to restore the integrity of the ligament. Rupture of the lateral collateral ligament more often leads to the development of instability of the knee joint, which is an indication for surgical treatment. After suturing the collateral ligament, a dosed load on the operated leg is indicated, for which it is necessary to use crutches. After collateral ligament replacement, the load on the operated limb must be limited for 12 weeks after surgery. Many doctors prescribe patients to wear braces and knee pads to stabilize the knee joint.