The knee joint, along with the ankle, are the two most commonly injured joints during sports. Statistics show that in each season, 4.8 – 6.8 out of every 1000 athletes who have no previous injury and do not use a special prevention method suffer a knee injury during a match or training. The mean time lost due to these injuries was reported to be at least 53 days.
Functional anatomy of the knee joint
The knee joint is basically a synovial joint formed by the cartilage-covered articular surfaces of the lower ends of the femur bone and the upper ends of the tibia bone (Figure 1). The patella or kneecap bone is located in front of the knee as an element of the muscle and tendon mechanism that extends the knee between the quadriceps and patellar tendons. The patella articulates with the anterior part of the articular surface of the femur.
Although the fibula is a bone to which the ligaments and muscles associated with the knee attach, it is not included in the bony structure of the knee joint.
Passive stability of the knee is primarily provided by lateral ligaments, cruciate ligaments, and menisci. The lateral ligaments protect the knee from internal and external opening (against varus and valgus forces). The medial lateral ligament consists of two components, one superficial and long, and the other deep and short.
The deep part also adheres to the inner meniscus. The external lateral ligament, which extends from the outer side of the femur to the upper end of the head of the fibula, does not adhere to the external meniscus.
Anteroposterior stability of the knee is provided in the foreground by anterior and posterior cruciate ligaments. These two ligaments also contribute to the lateral stability of the knee and prevent hyperextension and hyperflexion. Hyperextension is also prevented by the thick capsule and connective tissue behind the knee.
The inner and outer menisci, which are crescent-shaped pieces of fibrous cartilage, both help stabilize the knee during movements and provide transmission by softening the impacts that occur between the tibia and the femur bones.
Active stability of the knee is provided by the contraction of the surrounding muscles. The main muscle group that contributes to this stability is the extensor muscle group of the knee (quadriceps) and the flexor muscle group of the knee behind the thigh (hamstring muscles).
Ligament Injuries of Knee Joint
Ligament injuries to the knee joint should be considered serious injuries because of the potential for damage to the passive stability of the knee. They are as common as meniscal injuries and are encountered especially in contact sports such as football, handball, basketball, and skiing.
Ligament injuries of the knee joint are usually the result of a collision with an opponent in contact sports, but they can also occur when the physiological range of motion is exceeded in non-contact rotations and similar movements. As the energy transferred during injury increases, various ligaments are injured at various levels, depending on the position of the knee at the time.
The number of ligaments injured increases in proportion to the severity of the injury. The most common injury mechanisms are:
During sports, the blow to the outer side of the knee usually occurs when the knee is slightly flexed and firmly on the ground.
The knee is pushed inward, forcing the tibia to rotate outward relative to the femur. At first, the deep fiber of the lateral ligament and sometimes the inner meniscus, which is attached to it, are injured. If the impact is stronger, the superficial fiber of the ligament is also loaded and injured. The next stage is the injury of the anterior cruciate ligament. If the impact is too severe, even the posterior cruciate ligament may be injured.
It comes to the inner side of the knee while pressing the ground firmly with the knee slightly flexed.
The knee opens outward, it is the first loaded and injured external lateral ligament. The outer meniscus is less likely to be injured than the inner one, because the outer lateral ligament is not attached to the meniscus. As the severity of the injury increases, the anterior and posterior cruciate ligaments are injured, respectively.
Direct impact causing hyperextension or hyperflexion of the knee:
A frontal impact to the knee causes hyperextension. Indirect traumas can also be effective by the same mechanism. Falling while the knee is flexed is a factor of hyperflexion trauma. They may cause isolated anterior or posterior cruciate ligament injuries.
Rotational injury to the knee without body contact:
It is observed if the shoes are caught on the field floor while the athlete is moving or moving. It is a frequently observed injury mechanism in carpet pitches. Both meniscal and ligament injuries can occur together.
Findings and diagnosis
An important finding in knee injuries is pain. It is noteworthy that while it is very severe at the beginning, it gradually decreases. It gets worse again when the joint is moved or the leg is loaded. Another finding is localized tenderness over the injured lateral ligaments.
Sudden swelling in the joint is also a sign of an intra-articular injury. A swelling that comes on quickly is usually the result of bleeding.
In the interim, it can be confirmed that the cause of the effusion is bleeding by taking a sample of the joint fluid under sterile conditions. Joint instability is an important finding, although it may be difficult to recognize at the time of the initial injury.
After the acute period has passed, the athlete feels that there is a slack in the knee, especially when he starts the match again.
Knee ligament examination
An injured knee joint examination should always be performed by a qualified physician.
Thanks to the examination, it will be possible to prevent injuries early and without causing other injuries. For a correct examination, first of all, the contralateral muscles should be relaxed.
Investigation of the injury mechanism: if the injury mechanism is compatible with one of the previously described mechanisms, it will be easier to make a preliminary diagnosis.
Inspection of the injured area: Swelling may be observed around and even inside the joint. The presence of bruises in the region that fits the lateral ligaments indicates local bleeding and ligament tear.
Tenderness over the lateral ligaments is a valuable finding. Both lateral ligaments should be palpated along their entire tracing. In addition, the collapse of the patella towards the femur when pressed on the patella and its rise when released is an indication of fluid in the joint.
Evaluation of range of motion: Mechanical obstruction of range of motion may be a sign of a meniscal tear.
Stability examination: This examination is essential for the physician to be able to decide whether there is a significant ligament injury.
A successful examination is not possible without adequate muscle relaxation.
Examination of the lateral ligaments:
It is performed separately when the knee is in extension and flexed 20-30 degrees. In the injury of the lateral ligament, the knee will be angled outward (valgus), while in the injury of the lateral lateral ligament, the knee will be angled inward (varus). The degree of instability must be determined by comparing it with the opposite side.
If the pain is severe enough to prevent the examination, the examination can be postponed for two or three days or it can be done under anesthesia.
In a moderate CL injury, angulation of the knee to the valgus while the knee is at 20 degrees of flexion indicates injury to the deep fibers of the CL. If there is a comfortable angulation of the valgus even in full extension, it probably indicates injury to the anterior cruciate ligament along with the superficial fiber.
Anterior drawer test (Figure 4): Examination of the anterior cruciate ligament and the anterior lateral ligament together.
When the patient is lying on his back and the knee is flexed to 90 degrees, when the knee is pulled forward after the knee, the tibia coming forward is a sign of cruciate ligament insufficiency. If the same examination is performed with the knee in external rotation, anterior slip increases in medial collateral ligament insufficiency.
Lachmann test (Fig. 5):
Examines the anterior cruciate ligament. When the patient is lying on his back and the knee is flexed 20-30 degrees, when the thigh is fixed with one hand and then the knee is pulled forward with the other hand, the tibia coming forward is an important finding of anterior cruciate ligament insufficiency.
Posterior drawer test (Figure 6): It is used in the examination of the posterior cruciate ligament. When the patient is lying on his back and the knee is flexed to 90 degrees, when the knee is pulled forward after the knee, the tibia coming forward indicates a cruciate ligament insufficiency.
However, the final point of the knee in posterior cruciate ligament failure is the normal situation observed in the opposite knee. When the forward pull is terminated, the knee bends back again.
The physician decides whether a radiological examination is required in an injured knee according to the examination result. When examination is necessary, first of all, x-ray examination is performed. With this examination, it can be determined that the bone fragments are broken off from the attachment points of the ligaments to the bone.
If the physician deems it necessary, an MRI examination will give information about the condition of the ligaments and menisci with an accuracy rate of up to 95%.
Treatment of lateral ligament injuries
Treatment of lateral ligament injuries depends on the injured ligament, the level of injury, and other accompanying injuries. What needs to be done immediately at the time of injury is to stop the sport, relieve the joint from the load, apply a bandage around the knee and start cold compresses. If the knee joint is very unstable, an external brace may also be used (eg splint). After that, the patient should be brought to a doctor as soon as possible.
Injuries to the lateral ligament alone are usually treated conservatively. While only a bandage and special hinged knee brace can be given in a stage I injury (slight stretch in the ligament), it is preferred to use a plaster cast for up to 3 weeks and then use a special hinged knee brace in Stage II (tear in the ligament, but its continuity is preserved) and III (complete tear). is done.
A hinged knee brace is used for Stage I lateral ligament injury alone. While a 3-week plaster fixation is preferred in Stage II, repair of torn ligaments and adjacent tissues with an open surgical intervention in Stage III (complete tear) comes to the fore. After the repair, the plaster fixation takes 3 weeks and then special knee pads are used.
After all lateral ligament injuries, exercises are given even in plaster in order to preserve the functions of the quadriceps and hamstring muscles. After the plaster is removed, it is taken into an intense exercise program.
Treatment of cruciate ligament injuries
Surgical repair methods are not used today when the cruciate ligament is torn. Instead, the reconstruction of the ligaments, that is, the replacement of another tissue, is preferred.
The decision to reconstruct the cruciate ligament tear is made by considering many criteria such as the patient’s age, activity level, sportive level, previous injuries, and accompanying injuries.
In an anterior cruciate ligament tear, early reconstruction is performed in a young patient under the age of 24 -25 who wants to continue to do sports at any level, while in a businessman over the age of 35 who was injured while playing on a weekend, non-surgical methods may be preferred to follow-up the patient.
If there are signs of ligament failure in the future in this patient (such as frequent knee rotation, feeling of insecurity while doing sports, feeling of emptying while descending the stairs), we always have a chance for surgical intervention. In isolated posterior cruciate ligament injuries, non-surgical methods are more preferred in the early period.
In the early period of conservative treatment of cruciate ligament injury, it is followed by immobilization with plaster or special knee braces until the swelling in the joint decreases and the pain becomes unbearable (approximately 10 days). Even during this time, isometric muscle exercises are performed.
Exercises to gain full range of motion are added after the knee is moved. Return to sports should be after full joint movement and adequate muscle strength (80% of the opposite side) is gained.
Today, many different tissues can be used in the reconstruction of cruciate ligaments. These tissues are classified according to the regions they are taken from and from whom they are taken.
If tissue is to be taken from the patient’s own knee, the options we have are as follows: Patellar tendon graft taken together with the block from the patella and tibia, containing the middle 1/3 of the patellar tendon (Figure 7), Grafts containing the knee flexors (hamstring tendons) (Figure 8) Middle part of the quadriceps tendon Quadriceps tendon graft with a bone block from the patella, together with a cadaver graft.
Today, the gold standard in ACL reconstruction is the technique in which the middle 1/3 of the patellar tendon is used. Techniques using hamstring tendons are also preferred in daily use, with almost the same success rate and lower postoperative donor site complaints.
During the reconstruction, firstly, arthroscopic joint examination is performed and after the treatment of intra-articular problems is completed, the graft (such as patellar tendon or hamstring) to be used is prepared. Then, tunnels are opened first in the tibia and then in the femur and the graft is placed in these tunnels (Figure 9).
The stability of the graft in the tunnel is ensured by a suitable fixation method. This method is usually screw in bone-containing graft parts, and various suspension methods or staple techniques in tendinous grafts. After these attempts, return to contact sports takes 6 months at the earliest, and it can take up to 1 year. In order to return to sports, the condition that the muscle strength reaches 80% of the opposite side is also sought in this group.