Doctor Philippe Paillard 
Partial anterior cruciate ligament or ACL damage
Partial anterior cruciate ligament or ACL damage can be sustained as a result of a twisting movement of the knee. The damage can be assessed using the Lachman test. A firm endpoint and little or no translation are an indication of grade 2 ligament damage with elongation but continuity of the fibers. This may correspond to a simple hemorrhage on the MRI at the femoral attachment or an elongated but continuous appearance of the ligament on the MRI or with an arthroscopy. The percentage of ruptured fibers could also be a criterion for partial tears affecting 25 to 75% of the fibers, or high grade (> 50 %) and low grade (<50 %) subdivisions. If the femoral attachment is damaged, interstitial tears can be considered as partial ruptures. The diagnosis of partial ACL damage is based on a feeling of instability, an asymmetric Lachman test generally with a firm endpoint, absence of pivot shift or rotary translation, weak differential TELOS or GNRB laxity, and the 3D CUBE MRI appearance of the ACL.
Symptoms of partial ACL damage
When the trauma occurs, the person may hear a popping sound. Then comes the pain and/or swelling resulting in restricted movement and difficulty in straightening the knee. Walking is also painful and the patient feels knee instability. To detect partial ACL damage, there is nothing better than a clinical examination. An arthroscopy can be used for a clinical assessment of partial ruptures as well as to determine the extent of the damage. A Cube MRI can also be used to detect partial damage, but not to obtain a firm diagnosis.
Treatment of partial ACL damage
The treatment of partial ACL damage depends on the patient’s symptoms, the results of the physical examination, the remaining ligaments, sports activities, the level of sport, work demands… Surgery is not required with partial ACL damage. It is possible to recover a normal knee within a few weeks. However, medical and functional treatment is necessary to recover complete mobility. The patient must take anti-inflammatories and wear a ligament knee brace for 3 to 6 weeks. In most cases, these treatments work very well. Nevertheless, episodes of instability can be observed during walking or when resuming sport. Medical and functional therapy is most suitable for people who do not do much sport, as there is a lower risk of ending up with a functionally unstable knee. However, surgery is recommended for athletes, especially in the case of pivoting sports (football, tennis, handball, rugby, etc.).
Conservative post-op therapy must be initiated after the procedure: brace, rehabilitation, and muscle strengthening. After complete healing, which takes around 3 months, a full return to sports activities is possible. However, some patients having undergone functional therapy turn to sports that are less strenuous on the knee. Stability and function are acceptable if rotational activities are restricted.
