The cruciate ligaments of the knee joint are located centrally in the knee. They connect the femur and tibia and ensure stable mobility of the joint. Other ligaments and the muscles surrounding the knee support the anterior and posterior cruciate ligaments in this function.
Cruciate ligament ruptures usually affect the anterior cruciate ligament. The injury is often the result of sports accidents. The risk of sports injuries is highest in sports such as
- Soccer and other ball sports,
- skiing,
- tennis,
- kitesurfing,
- trampolining.
They require abrupt braking and acceleration in combination with complex knee movements.
In contrast, the posterior cruciate ligament tears much less frequently. Such injuries result from direct force on the bent knee, for example in martial arts or traffic accidents.
The position of the cruciate ligaments in the knee joint © Henrie | AdobeStock
Cruciate ligament surgery is the most common procedure for the surgical treatment of a torn cruciate ligament. During the procedure, the surgeon removes the non-functional, torn parts of the cruciate ligament from the knee joint. He then replaces it with a transplant.
Basically, the transplant can be
- a tendon from the patient's own body,
- donor material or
- synthetic replacement material
can be considered.
Almost all operations today rely on autologous transplants. In most cases, one of these three autologous tendons or tendon parts is used:
- the semitendinosus tendon belonging to the posterior thigh flexor muscles: today the standard choice for non-professional athletes
- a piece of the quadriceps tendon of the large thigh muscle
- a piece of the patellar tendon located below the kneecap
The function of the removed semitendinosus tendon is compensated for by neighboring tendons.
In principle, the muscles surrounding the knee can compensate more or less well for a torn cruciate ligament. Once the acute pain and swelling have subsided, the injured knee is typically mobile and able to bear weight again.
However, the tear often leads to abnormal instability of the knee joint. The patient also notices this.
If left untreated, a cruciate ligament tear also leads to incorrect loading of the knee. This often results in subsequent injuries or osteoarthritis of the knee joint. Osteoarthritis is the painful wear and tear of a joint. In its later stages, osteoarthritis is a frequent cause for the use of an artificial joint.
A torn cruciate ligament cannot grow back together and heal on its own. In order to avoid the consequential damage described above, cruciate ligament surgery is often unavoidable.
Cruciate ligament surgery is generally performed a few weeks to months after the injury. By then, the swelling of the knee caused by the injury has subsided and the joint can move well again.
During this time, the patient should train their joint, for example as part of physiotherapy. This restores normal mobility and muscles and trains movements that are gentle on the joint.
Sometimes, especially in older patients, this form of conservative therapy is already sufficient.
A cruciate ligament plastic surgery is recommended if:
- there is a high sporting or occupational mobility requirement,
- patients are subjectively unable to cope with the injury,
- the knee joint shows significant instability or
- other structures of the joint areinjured.
Even after an attempt at conservative treatment, it is not too late for surgery.
Minimally invasive knee arthroscopy (arthroscopy) is the most common and gentlest procedure for cruciate ligament plastic surgery. The procedure typically takes between 45 and 90 minutes.
General anesthesia or spinal anesthesia can be used to eliminate pain during the operation. The latter blocks the sensation of pain in the lower half of the body.
Knee joint surgery is performed using an arthroscope. This is a thin camera that the surgeon inserts into the joint through small incisions. The camera image from inside the joint is then enlarged and displayed on a screen.
The surgeon first uses the arthroscope to gain an overview of the damage to the cruciate ligament. He also looks to see if there are any accompanying injuries. If such injuries are visible, they are treated, for example by suturing or partially removing damaged parts of the meniscus or cartilage surgery.
The surgical team then removes the tendon intended for transplantation through a 3-4 cm long incision. It is then prepared for transplantation.
The tendon is then transplanted. Using the fine surgical instruments of the arthroscope, the surgeon first removes the remains of the torn cruciate ligament. The attachment points of the ligament to the bone are left in place. Here he drills fine holes in the femur and tibia. The graft is fixed into these holes.
Finally, the surgeon inserts a small drainage tube if necessary. This drains fluid from the operated joint over the next few hours. He then sutures the surgical wounds.
You will remain in hospital for one to two days after the operation. During this time, with the support of hospital staff, you will make your first brief attempts to stand up and walk using crutches. It is important to keep the joint in an extended position for the first 24 hours. This prevents the freshly transplanted tendon from shortening.
To reduce the risk of thrombosis, you should resume physical activity as soon as possible. Thromboses are vascular blockages caused by small blood clots. They can form if you are inactive for too long. For the same reason, you must first inject blood-thinning medication after the operation and wear compression stockings if necessary.
In the following weeks, you will carefully get your knee "back into action" under intensive physiotherapeutic supervision. In the first few weeks, you must not bend or strain it too much. Cooling, elevating the leg and manual lymph drainage reduce the joint swelling.
After 4 to 6 weeks, patients are usually able to fully bend their knee. They also no longer need walking aids.
How quickly you can start doing sport again depends on the individual. Physiotherapists and sports physicians use so-called return-to-sports tests to assess how resilient the operated knee already is. On average, athletic cruciate ligament plastic surgery patients can
- cycle and swim on the road again after six weeks,
- jogging and more demanding biking after three to six months, and
- skiing, ball sports and martial arts after nine to twelve months.
Infections of the operated joint are among the most critical, but very rare complications of cruciate ligament surgery. An infection can affect up to 0.8 percent of patients and, in the worst case, destroy the joint.
Patients also rarely suffer from scarring in the joint after the procedure (arthrofibrosis). Scars can cause the knee to stiffen. A second operation is then necessary to correct the scars.
The most common complication is a new cruciate ligament rupture on the operated or opposite side (also increased risk). This complication affects around 10 to 15 percent of injured people. Young and active people in particular have an increased risk of this.
The donor site of the transplant can also cause problems. If a patellar tendon is used as a graft, around half of patients still suffer from pain 1-2 years after the operation.
According to study results, cruciate ligament surgery produces better results than conservative treatment. However, this requires good cooperation from the patient. The patient must consistently build up their muscles and not put too much weight on the joint too early.
Patients who have undergone surgery achieve a higher level of performance on average than patients who have only undergone physiotherapy. According to current studies, the replacement of the anterior cruciate ligament is clearly recommended, especially for young (including children) and active patients. Surgery is then also used to prevent consequential damage and a reduction in physical activity.
Isolated cruciate ligament ruptures generally have a very good prognosis. These are tears without any other accompanying damage to the joint.
Whether the replacement of the cruciate ligament can prevent or delay the later development of osteoarthritis in the injured knee is controversial. Initial long-term studies following anatomical cruciate ligament reconstruction show that surgical stabilization of the joint has a positive effect in this case.
