ACL Injury

Synonyms in the broadest sense

Ruptured anterior cruciate knee ligaments, ACL, ACL-rupture, cruciate ligament lesion, anterior knee instability, anterior knee ligament insufficiency, chronic insufficiency of the anterior cruciate ligaments of the knee, cruciate ligament rupture, cruciate ligament plastic, cruciate ligament replacement, anterior cruciate ligament of the knee

German: vorderer Kreuzbandriss

Definition

A fresh rupture / injury of the anterior cruciate knee ligament (ACL-Injury) is the complete or partial laceration (rupture) of ligament continuity after exceeding their overexpansion reserves by an external violent force. A previous rupture of the anterior cruciate ligament that usually is caused by an accident persists as a persistent, ligament damage.

Anatomy of the cruciate ligament

Thigh head roll (femoral condyle) Interior meniscus Anterior cruciate ligament (ACL) Shinbone heading (tibia head) Exterior meniscus

Our knee joint may well be designated as a biomechanical miracle. It must endure and balance a multitude of burdens. This task is performed on one hand by the musculature and on the other hand by ligaments, meniscus and the capsule tissues. The cruciate ligaments, of which we process an anterior cruciate ligament and a posterior cruciate ligament, lie crossed-over, as the name suggests, from the middle of the shinbone head to the thigh bone. These ligaments stabilize the knee, according to their course direction "in running direction". That means by attachment to the shinbone that they prevent the femur from extending forward beyond the shinbone or vice versa. The anterior cruciate knee ligament is tightened, if the shinbone attempts to swerve forward; the posterior is tightened if the opposite direction is stressed. In addition, the ligaments have been provided with measurement sensors (proprioceptors), which provide our spinal nerves with important information about the spatial position of the leg. This affects directly the coordination of various muscle groups that participate in walking. Walking is a transaction that is controlled in such an extremely complex manner that to date no computer has been able to duplicate this as perfectly as mankind has mastered it.

Causes for rupture of cruciate ligaments

The causes are often so-called "Flexion-Valgus-Exterior-Rotation-Injuries". That means that the knee was bent involuntarily into a crossed-leg position during a dynamic movement, with the calf being firmly twisted outwards. Typically, such injuries occur while skiing or playing soccer. By loosening the capsule ligament apparatus (ligament rupture, interior ligament rupture, capsule rupture), instability of the knee joint can occur. This movement results is a derailment of the natural rolling-gliding mechanism of the healthy knee joint. A chronic instability leads to continuous cartilage abrasion (knee arthrosis = Gonarthrosis) and damage to the meniscus (meniscus tear / rupture).

Classification

In order to document the extent of the injury (rupture of the anterior cruciate ligament), the anterior drawer test is often performed. Thereby the knee joint is bent to 90° and the foot is fixed to a base. Now, the doctor pulls on the lower leg just below the knee joint and observes, whether the shinbone can be pulled forward in relation to the thigh. This could be an indication of anterior knee joint instability.

Classification of the anterior drawer symptom according to Debrunner:

Grade I (+), slight shift of 3-5 mm

Grade II (++), moderate shift of 5-10 mm

Grade III (+++), significant shift of > 10 mm.

Complaints

Am important illness indicator (symptom) with each acute ligament injury of the knee joint consist of significant pain, which occurs immediately at the moment of the injury (trauma); it disappears immediately thereafter and reoccurs upon renewed stress. By rupturing the ligament structure, blood vessels are simultaneously lacerated (ruptured). Thereby, bleeding occurs in the knee joint (hemarthrosis). If blood is withdrawn, when a needle puncture of the knee joint is undertaken due to a strong knee joint contusion, this is always a strong indication of ligament injury in the knee joint. According to individuals, instability of the knee joint varies after acute symptoms have disappeared. After a rupture of the anterior cruciate ligament, complaints are often made about instability especially when climbing stairs. Sometimes a ruptured cruciate ligament is only diagnosed years after the accident, perhaps because no significant knee instability was established. Sometimes, an anterior cruciate ligament rupture can be combined with a posterior cruciate ligament rupture (posterior cruciate ligament rupture).

Diagnose

If patients with a cruciate ligament rupture reach a doctor, they sometimes suffer very severe knee pain. The knee is usually very swollen within the first few hours after the injury. The doctor tries to examine the knee with so-called stability tests (a.m. drawer test). Due to general painfulness, this is often difficult, since the patient tightens his muscles, because he expects even more pain from the examination. Thus it can occur that the stability examination of the knee joint is of little predicative value after a fresh injury.

A normal X-ray image (Roentgen) indicates eventually existing skeletal injuries (e.g. shinbone head rupture (tibia head fracture)). A significant joint contusion should be punctured, in order to relieve the cartilage and joint capsule from the pressure of the bruise. If the contusion is bloody, a cruciate ligament rupture can be presumed, although this is not yet definitive evidence. Upon the general acceptance of nuclear magnetic resonance imaging (MRT, NMR) as a process to produce an image, the diagnosis of a ruptured cruciate ligament has been simplified. The cruciate ligaments or their remnants can be very well presented in MRI. A diagnosis of ruptured cruciate ligaments can be made with a great degree of certainty. In the figure above, the red arrows indicate a ruptured, cruciate ligament (rupture of the anterior, cruciate ligament). With the aid of nuclear magnetic resonance imaging, the ligament damage can be ascertained. The level images indicate the course of the cruciate ligaments and their points of insertion on the femur or tibia bones. In the event of a rupture, the fibrous strands are not continuous and the localization of the rupture is made possible. Up to a few years ago, one urgently dragged patients with suspected rupture of cruciate ligaments to the OP table. These times have passed, since injuries that have occurred can now be quite accurately diagnosed with the aid of Nuclear magnetic resonance imaging (MRI) and required operations can be planned, as needed. The X-ray image is normally inconsequential with isolated cases of ruptured cruciate ligaments. But since similar symptoms can also be caused e.g. by a Meniscus rupture, it is difficult for amateurs to make a diagnosis.

Here all investigative methods are given once more to diagnose a ruptured / injured anterior cruciate ligament:

Clinical Diagnosis (Examination):

• Observation of swelling of the knee, joint contusion, scope of movement and movement pain
• Observation of the manner of walking, leg axis
• Observation of the femur patellar joint (sliding support of the knee cap)
• Observation of the knee stability and meniscus
• Muscular atrophy (weakening of the muscular relaxation)
• Observation of adjacent joints
• Observation of circulation, mobility and sensitivity (skin sensitivity)

Apparative Diagnosis:

Roentgen (required):

Knee joint in 2 levels, patella (knee cap) tangential

Roentgen (useful):

• Knee joint, p.a. in a standing position in 45 degree flexion
• Frik`s image (tunnel image)
• Fixed image
• Whole leg image under stress
• Function image and special projections

Sonography

• Observation of effusion
• Baker cysts
• meniscus ganglion

Computerized tomography (CT)

• Observation and estimation of special bone fractures, e.g. tibia head fracture

Magnetic resonance imaging (MRI)

• Observation of e.g. cruciate ligaments, lateral ligaments, meniscus, bone injury, bone edema (bone bruise)

Needle puncture

• with synovial analysis to observe contusion: Blood? ligament lesion Fat droplets? bone fracture

Therapy / Operation

As with most things in life, two options exist: either a conservative or a surgical therapy will be strived for. The therapy must be oriented towards the individual circumstances and demands of the patient. A professional athlete will want to return to his sport as quickly as possible and demands that his knee will remain stable under extreme stress situations. The 60 year old chess player will be more able to forego this and thus will be made happy without an operation. Some doctors are of the opinion that an Osteoarthrosis will always occur after a ruptured cruciate ligament without an operation; it is only a matter of time. Therefore, the different therapies will always be hotly disputed. Affected patients must weigh the advantages and disadvantages with their doctors in detail.

The conservative therapy

After dissipation of acute pains, usually periodic physical therapy will be prescribed after adapting a plastic brace (knee joint orthesis). This improves a strengthening of the muscles; coordination exercises increase the stability of the injured knee joint. In addition, therapy can be made singly or in combination with stimulating current, ultrasonic and cold treatment. Hereby, metabolic transactions will be stimulated which reduce the swelling, increase the circulation and cause a reduction of pain. But it is important to know, that a life-long, consequent, independently performed muscle training is required, in order for the muscles to be able to undertake the tasks of the ruptured cruciate ligaments. For this reason, some individuals do not succeed.

Physical and physiotherapeutic measures

Goals: Functional improvement of the knee joint, muscle structure, improvement of the coordination and proprioception, Prevention of muscle shortening (contractures), reduction of pain, stabilization of the knee joint.

Suitable therapeutic measures

• Physiotherapy (remedial gymnastics)
• joint-protection training
• cryotherapy (cold therapy)
• ultrasonic therapy, electrical current therapy
• ergotherapy
• manual lymph drainage

Orthopedic technique

• Crutchers or forearm-supported canes
• knee braces

The surgical therapy

The decision to operate depends from many factors, as mentioned:

• Age
• Activity
• Profession
• Accompanying injuries (meniscus rupture) etc.

Younger patients, who are active in sports, are usually advised to have an operation, because long-term damages (knee arthrosis) that also occur through even minimal knee instability are also feared.

The most frequent surgical methods are the so-called cruciate ligament plastics. Thereby, a piece of the body’s own tendons is grafted as a cruciate ligament replacement (transplantation) onto the knee. The operation should not be performed immediately after the injury, since the risk of a post-operative joint scarring (arthrofibrosis) is especially great in the first days after an accident. The cruciate ligament sutures that were previously routinely used are practically no longer applied, because they have been demonstrated to be unsuitable. But everything is not accomplished by the operation itself. A similarly strenuous re-treatment is required, such as with the conservative therapy. A 6-week re-treatment until the knee joint achieves complete stress capacity may be the laudable exception, which should be sufficient for our soccer stars time and again. However, generally a 3-month re-treatment time is a good average.

How will an anterior cruciate ligament rupture be treated?

With an anterior cruciate ligament rupture, it is essential to restore the lost, interior support of the knee joint. Hereto, the anterior cruciate ligament must be restored as much as possible to its natural state (anatomically reconstructed). Thereby, the new cruciate ligament (cruciate ligament plastic) should resemble the features and functions of the natural anterior cruciate ligament as much as possible. The application of the so-called knee cap tendons (patella tendons) as well as the so-called hamstring (tendons of the interior, thigh muscle: Musclus semitendinosus and Musculus gracilis) have been shown to be especially useful.

1. The patella tendon graft:
   With the patella tendon plastic, an approximate 1 cm wide piece of the tendon will be removed from the middle third of the knee cap tendon, and in fact with a block of bone, 2 x 1 cm wide, adhering to both ends from the knee cap patella and the shin bone, respectively. The advantage of applying the knee cap tendon is the good attachment possibility. The appended bone blocks will be fixed in the drill channels with so-called interference screws made of Titan or saccharide. The implantation and fixation of the grafts is performed today in a purely arthroscopic manner through a Knee joint endoscopy).
2. The semitendinosus tendon graft
   (tendons that are taken adjacent to the knee joint at the interior portion of the upper thigh).
   This tendon graft will be taken via a small skin incision on the inner side of the shin bone head. According to the length of the tendon tissue that was removed, it will be consolidated to the required length of the cruciate ligament replacement graft. (triplicate or quadruple transplant). The primary tensile strength of a quadruple-hamstring-graft (quadruplicate-laid tendon graft) is approximately double as great as the tensile strength of the normal, human anterior cruciate ligament.
   The advantages of the semitendinosus- and gracilis-grafts are a minimal rate of complication at the site of removal, minimal pain after removing the tendons, and a very, small cosmetic, skin scar.
   Furthermore, this graft rather achieves the firmness of a normal anterior cruciate ligament. Movement limitations are demonstrably less seldom than with the patella tendon graft. The maximal tensile strength of the quadruple-hamstring-graft is still greater than that of the patella tendon graft.
   The slower healing behavior of tendons into the bone channels is regarded as a disadvantage in comparison to the patella tendon graft. The bone blocks of the patella tendons grow within 3-6 weeks; the hamstring-tendons require 10-12 weeks for that. The long-term results of both of these possibilities are about the same for replacing cruciate ligaments with regard to stability and function of the knee joint.

Which of the available techniques for replacing cruciate ligaments will finally be implemented depends on many factors, such as e.g. age, sex, profession, sport activities, height, weight and tissue structure. The fixation of the graft occurs either with so-called interference screws (also obtainable from materials that can be dissolved) or with titan clamps. Although the techniques appear to be relatively complicated, the rate of success is good following an operation to replace cruciate ligaments, especially if no essential supplemental injuries exist. This aspect argues in favor of the earliest possible repair of such a situation.

The anatomical reconstruction of the original course of the anterior cruciate ligament is decisive for the surgical success of an anterior cruciate ligament plastic by means of semitendinosus tendons or patella tendons. For example one can recognize to the right the optimal course of a transplanted semitendinosus plastic. The ends of the tendons are fixed to the bone with a so-called Endobutton. Hereby the primary stability of the new cruciate ligament will be guaranteed. In the subsequent healing process the tendon transplant must then grow into the bone.

The two standard transplants for a cruciate ligament plastic are the patella tendons (refer to the figure below) as well as the semitendinosus tendons / gracilis tendons (refer to the figure above). For the knee cap tendons (patella tendons) generally the middle third of the patella tendon will be removed with a bone block attached to both ends. In order to remove the semitendinosus tendon, the tendon will be removed from the bone by means of a small opening in the skin; then it is detached from its muscle body with a stripper. The tendon residue forms a scar without any essential, demonstrable loss of function with its environment.

Interior reinforcement operation

In acute and sub acute cases, i.e. if the accident, itself, happened in the not too distant past, a treatment method consists therein to reinforce the „old“ anterior cruciate ligament .from within with a new structure and thereby to restore the conditions, which very closely resemble the original circumstances. This technique, which is offered quite infrequently, has the following advantages:

1. One’s "own" anterior cruciate ligament with its so-called proprioceptors, i.e. nerve sensors, which are very important for the fine-tuning of movement and muscle actions, can be extensively retained. This is naturally not possible with a replacement graft.
2. The grafted tendon material (quadruple semitendinosus tendon) is unsheathed from the onset, which provides ideal growth adaptation conditions for the implanted material.

Unfortunately, this special technique is unsuitable for chronic instabilities, which lie partially in the distant past, since in these instances the "old" anterior cruciate ligament is usually no longer available. It is regrettable that long-term results are not available, so that an unreserved recommendation cannot be made at this time about this OP technique.

How is a ruptured posterior cruciate ligament treated? More about this subject is given on the page posterior cruciate ligament rupture.

Aftertreatment

Mal schaun wie das mit den tabellen werden soll...

Complications

The following pertain to general complications:

• Infection, disruption of wound healing
• Thrombosis, pulmonary embolism
• Damage to tissues and nerves
• Movement limitations
• Residual instability

A feared complication after an operation to replace cruciate ligaments is the Arthrofibrosis. Hereby one interprets an excessive scarring of the joint with partial stiffening of the knee joint. The danger of an arthrofibrosis is especially increased in the first week after the rupture of the cruciate ligament; therefore, the operation is usually performed with a 6-week delay after the accident.

Prognosis

It has been scientifically demonstrated, that a rupture of the cruciate ligament can cause irreparable damage to the knee joint. With a high degree of certainty, a knee joint will demonstrate premature cartilage damage (gonarthrosis). This cartilage wear is caused by the instability of the knee joint. Even instability of the knee joint that the patient barely notices can cause premature cartilage attrition. Whether a cruciate ligament plastic can exert a positive effect on this process has not been scientifically, demonstrated unequivocally, but a positive effect is presumed according to subjective estimates.