Anterior cruciate Ligament

The incidence of ligamentous lesions of the knee joint is still increasing. Sports injuries in soccer and alpine skiing are the main cause for ACL ruptures. The typical injury pattern is caused by mechanical overload of the knee joint in flexion, external rotation and valgus position. The external rotational forces may lead to lesions of the medial collateral ligament and to strain or even rupture of the ACL. Quite frequently there are associated lesions of the menisci. The ACL is a very important stabilizer of the knee joint. Patients with a torn ACL feel some laxity and suffer from “giving way” episodes, mainly during their sports activities. Even well developed muscles can only partially compensate for the mechanical instability of the joint. Many patients can continue their previous sport but have to accept a lower activity level. Particularly sports like soccer, handball, tennis, basketball or alpine skiing (“rotational sports”) are very demanding to the knee joint and difficult to continue. The laxity and the disturbed joint mechanics (increased friction, pathological changes of the centre of rotation and higher peak forces) are the reason for subsequent damages to the menisci and cartilage on the long run, which is the onset of osteoarthritis. Therefore especially patients with higher sports activity level need early operative treatment. The primary goal of the operation is to stabilize the joint and to avoid late posttraumatic degenerations of the joint after ACL rupture. Since the suture of a ruptured ACL does not give good results for biological reasons, the ACL should be augmented or replaced with autologus tendon material. Today ACL reconstruction with autologus material has reached a very high technical level and is based on a vast experience over decades. Artificial ACL implants have shown poor long term results and are given up almost completely.


Today the graft material of choice are tendons from the flexor muscles (hamstrings) like semitendinosus tendon and gracilis tendon or patella tendon (BPTB) and quadriceps tendon also. These tendons have proven their value as graft material over many years. Their tensile strength and elasticity is similar to the natural ACL. In numerous studies from different authors excellent results are documented. The tendon of the semitendinosus muscle is becoming the graft material mostly used. The harves-ting of the tendon is very well tolerated without losses of muscular strength or range of movement. The excision of the tendon is done by the help of a stripper through a small skin incision which leaves a barely visible scar. The ACL reconstruction is done completely endoscopically and causes much less surgical trauma than the former conventional operations. There is much less pain and early functional treatment makes rehabilitation rather easy. The crucial part of the operation is the exact placement of the bony tunnels which are the insertion points of the transplant. These points have to be placed exactly where the natural ligament originates. By the help of very precise aiming devices the drill holes are made under arthroscopic control. In order to increase tensile strength the original semitendinosus tendon is folded three to four times (tripled or quadrupled graft). After its final preparation the graft is pulled through the tibial tunnel into the femoral drill hole where it is fixed with resorbable pins (cross-pin-fixation). As an alternative the graft can also be fixed over a small titanium plate (endobutton). For fixation at the tibia we use a small titanium button. This new system gives a very stable anchorage which is essential for the biological incorporation of the tendon. Normally, the removal of implant material like graft and button is not necessary. Associated lesions of the menisci and of the cartilage can be treated at the same occasion. ACL reconstructions are done normally on an outpatient basis or as day cases.

The rehabilitation program after ACL reconstruction is a combination of early functional treatment and intensive muscle exercises as well as a training program for automatic control and coordination. Continuous passive motion (CPM) and partial weight bearing are favourable for transplant healing and nutrition of the cartilage. Electrical stimulation may be useful for the improvement of the muscular function. For protection an adjus-table knee brace is applied.

Teamwork between patient, physiotherapist and surgeon is essential for a satisfactory outcome of the procedure. Most patients will reach full weight bearing after three to five weeks. This depends on the quality of their active muscular control. Whereas immediately after the intervention physiotherapy with sessions of 30 minutes are done three to four times a week, after the third week postoperatively, intensive therapy with 2-hour-sessions are started for at least three times a week. Depending on the possible knee flexion, work on an exercise bike is an excellent form of muscle training and work-out in general. After the muscles or the thigh are well built up, rotational sports like soccer, handball, basketball and alpine skiing can be practised again. The functional results after ACL reconstruction are usually very good and as a routine the patients can continue their sports on their previous level.

Step one (3.3 MB)
Step two (1.0 MB)
Step three (1.6 MB)