Anterior cruciate ligament
The typical injury mechanism is an overload of the knee joint in bending, external rotation, and knock knee positioning. The rotational forces having an effect on the knee injure the interior ligament, and often also injure the internal and external meniscus. This leads to overstretching or to a tear of the anterior cruciate ligament.
The anterior cruciate ligament is a crucial stabilizer. The patient with a torn cruciate ligament complains about a feeling of unsteadiness, and above all complains of the knee joint "giving away" during sports. A very well conditioned musculature can in part balance out the instability. One can usually no longer engage in sports like football, handball, tennis, basketball, and Alpine skiing (sports with rotational movements). Instability and the related disturbance of the joint mechanics (increased friction, change in the rotational point, and change in the distribution of the pressure) in the long run cause further damage to the inner and outer meniscus and to the cartilage. This is the beginning of an arthrosis. That is why especially in patients who are athletes the unstable knee joints should be operated on as soon as possible. The primary goal of the operation is to make the joint "stable" in order to prevent further damage to the meniscus and the joint cartilage. Since the single ligament suture on biological grounds cannot bring about stability, strengthening must take place or a replacement must be made with the body's own ligament material.
In most cases, we use the semitendinous ligament as the replacement for the cruciate ligament. As an alternative, we use the patellar ligament or the quadriceps ligament. The substitute ligaments have proven themselves over many years in cruciate ligament surgery. The ligament material has a similar resistance to tearing and an elasticity similar to the natural cruciate ligament. Many studies have proved the excellent results. The semitendinous ligament is one of several bending ligaments on the knee. Removal of the ligament is tolerated without loss of strength or mobility. Removal of the ligament through a small skin incision on the interior side of the knee leaves a barely visible scar. The anterior cruciate ligament replacement operation, performed by arthroscopy, is a much less stressful operation for the joint than are open operations. The pains after the operation are much less, and the rehabilitation can be begun quite early on. The exact placement of the bone canals in the insertion points of the original cruciate ligament is crucial for the success of the operation. The use of precise targeting tools allows these boreholes to be made exactly under arthroscopic monitoring. In order to maintain sufficient resistance to tearing, the ligament is folded 3 or 4 times.
The replacement ligament is first drawn into the joint through the bored canal at the head of the leg bone, and then fastened in the bony canal of the thigh with the aid of two resorbable pins (cross pin anchoring). The alternative fixation with a small titanium plate in conformity with the folding plug principle has also proved to be successful. We use a small titanium knob to fasten the ligament to the head of the leg bone. This new fastening principle allows a very stable anchoring and guarantees ligament healing without problems. Later removal of the metal can usually be dispensed with. Accompanying damage to the menisci or to the cartilage can be treated at the same time. In promising cases, the meniscus can be sutured and thus maintained. Cruciate ligament replacement operations are done on an outpatient or short-term inpatient stay basis.
Rehabilitation after an anterior cruciate ligament operation essentially consists of early movement exercises, an intensive muscle build up program, and coordination training. Continuous movements on a passive movement machine and incrementally increased load bearing have a very positive effect on feeding the cartilage and healing the area of the transplant. The muscle atrophy of the thigh can be reduced by using muscle stimulation devices. To protect the transplant, for several weeks a removable and adjustable splint (orthosis) should be worn.
Only good cooperation among the patient, physical therapist, and an experienced operating physician leads to a good result of the operation. Most patients achieve full load bearing after 3-5 weeks. Expanded outpatient rehabilitation begins in the third week. The bicycle ergometer has proved itself the best item as a training device. With well redeveloped thigh musculature and regained stability, after 6-8 months rotation sports like football, handball, basketball, and Alpine skiing can be begun again. As a rule, the results of the operation after anterior cruciate ligament reconstruction can be called very good. In most cases, patients can continue their support at a high level.