Dynamic Intraligamentary Stabilisation (DIS)

Patient information on new surgical techniques for rupture of the anterior cruciate ligament


Rupture of the anterior cruciate ligament is the most common ligament injury of the knee joint. The injury usually arises from weight-bearing flexion of the knee and outward rotation of the lower leg, which leads to a sudden overloading of the anterior cruciate ligament. If a force of more than 200 kg is exerted on the knee, the anterior cruciate ligament will rupture. In Switzerland alone, more than 7000 anterior cruciate ligament ruptures require surgery every year, most commonly happening when skiing or playing football. Interestingly, more women than men suffer this injury when undertaking the same sporting activities. Until now it was commonly believed that the cruciate ligament would not heal by itself and the knee joint would therefore remain unstable. The only way this could be remedied in the past was by replacing the cruciate ligament with a tendon graft from the leg. However, a research group at the Sonnenhof Orthopaedic Hospital in Switzerland, under the direction of Prof. Dr. Stefan Eggli, has now developed a procedure, which can bring about natural healing of the ruptured cruciate ligament.



The function of the anterior cruciate ligament

The main function of the anterior cruciate ligament is the stabilisation of the knee joint. In particular, the cruciate ligament limits the forward movement of the lower leg. In addition, the anterior cruciate ligament is the ‘antenna’ of the knee joint. The numerous sensitive nerve fibres in this ligament continuously transmit messages about the positioning of the knee joint back to the thigh and lower leg and therefore play a definitive role in controlling the normal movement process. Rupture of the cruciate ligament results in a loss of this control function, a feeling of tentativeness and instability of the knee joint, the severity of which is determined by muscle condition.


Conventional treatment methods

In the past, it was not possible to save the patient’s own cruciate ligament after a rupture. It was therefore necessary to completely remove the ligament and replace it with a donor tendon from the same leg. Whilst this ‘donor’ ligament does re-stabilise the knee joint, it cannot assume the control function of the original cruciate ligament, as it no longer has any nerve fibres and is, de facto, dead. It is well known from the literature that whilst the knee joint stability can be re-established, the function and feel of the knee joint is rarely judged to be normal by the patients.



Natural healing of the ligament DIS

Knee joint surgery on patients at the Sonnenhof Orthopaedic hospital, under the direction of Prof. Dr. med. Stefan Eggli, has now been able to demonstrate that with a new procedure known as ‘dynamic stabilisation of the knee joint’, the ruptured cruciate ligament can be immobilised such that spontaneous healing can take place. The core element of this ‘dynamic intraligamentary stabilisation’ (DIS) was developed in cooperation with the innovation group at the medical technology company, Mathys AG Bettlach, Switzerland. It consists of a polyethylene suture - anchored in the thigh - and a spring screw system in the lower leg, which stabilises the knee joint every time it moves. This achieves the appropriate level of immobilization required for the rupture to the cruciate ligament to heal. In addition, a microfracturing procedure is carried out, which transports stem cells to the rupture site, thus further promoting healing of the ligament.

Indications for the procedure

In principle every newly ruptured cruciate ligament is suitable for the DIS procedure. The more actively involved a person is in sport, the more he or she needs the function of the anterior cruciate ligament. Immediate surgery is therefore recommended for highly active young people, but with older patients who do not undertake a high-level of sport, more conservative therapy can also achieve a good result. The decisive factor is whether the thigh muscles are able to stabilise the knee joint well and intensive physiotherapy is necessary to achieve this. If, however, in spite of this the required level of stability cannot be achieved, the next step is surgery to stabilise the knee. In the latter case, the only suitable procedure would be conventional stabilisation surgery, which involves removal of the rest of the cruciate ligament nerve fibres and a tendon graft. 
It is therefore essential to decide immediately post-accident whether a DIS procedure should be carried out, in an attempt to retain the patient’s own cruciate ligament.


Post-operative treatment

The surgery usually takes less than an hour and can be carried out using epidural (caudal) anaesthesia. The period of hospitalisation is between two and four days, depending on post-operative pain. The leg is placed in a thigh splint for four days, so that initial healing can take place. The level of weight bearing is then determined by the level of pain, but the aim is to become fully weight bearing as soon as possible. An exception to this can be an injury also involving a tear in the meniscus, where for a certain period of time, the knee joint cannot be fully weight-bearing.
A course of physiotherapy is introduced immediately, in order to mobilise the knee joint, build up strength and monitor muscle control. It is also important to prescribe anti-thrombolytic medication for a minimum of 10 days. This is usually in the form of an injection or a daily tablet. The first check-up is carried out by the surgeon three weeks after the operation and if all is well, the patient can commence running after 6 weeks; ‘stop and go’ sports after 12 weeks; contact sports (football, hockey) and skiing after 5 months.


Advantages and the future

The major advantage of this method, as compared to the conventional cruciate ligament graft, lies in the ability to retain the patient’s own living cruciate ligament and therefore its function as the ‘knee joint antenna’. In addition, it is no longer necessary to take a tendon from somewhere else, which considerably reduces the surgical intervention. Prof. Eggli and his team are therefore of the opinion that in the future it will be possible to carry out this type of operation on an outpatient basis, in contrast to conventional cruciate ligament reconstruction, which requires approximately three days in hospital. The Bern research team also expects that the healing process will also be much quicker than before, which for the ambitious sportsman or woman will be a decisive factor. And ultimately, the first results show that after 6 months, patients are virtually unaware of any difference between their injured knee and the other one and have practically normal knee joint function. 

Highest recognition for Bern research team

At the annual meeting of the German Association for Orthopaedics and Accident Surgery (DGOU Berlin 2011), the highest paid research prize went abroad. 
The German prize for innovation was awarded for the new ‘dynamic intraligamentary stabilisation’ procedure, which was developed by the knee research team at the Sonnenhof Klinik and Inselspital in Bern, Switzerland under the direction of Prof. Dr. med. Stefan Eggli. The award recognises the research in particular as a forward-looking technique, which allows patients to retain their anterior cruciate ligament after trauma.