Cruciate ligaments

Why is cruciate knee ligament damage so famous ?

Probably the most feared injury for footballers, cruciate ligament damage seems to be an insurmountable task in the minds of some players. However, it is essential to know that this injury can be properly rehabilitated in order to regain its pre-injury sensations. Indeed, although long and difficult, the rehabilitation of the cruciate ligaments allows the athlete to regain his or her level, provided that he or she has patience and perseverance. It should be noted that not all cruciate ligament injuries are necessarily operated on, although in high-level sportsmen they are almost systematic. Prevention also plays a particular role in considerably reducing the probability of injury and we will see in this article how to work specifically on it. 

Overall, the cruciate ligaments (ACL and PCL) form the central pivot of the knee and are responsible for limiting excessive anterior/posterior knee movement (1). The ACL acts to resist anterior translation of the tibia but also against internal rotation of the tibia and valgus angulation at the knee. The primary function of the ACLPI is to resist posterior translation of the tibia onto the femur in all knee flexion positions. In 70-80% of cases, cruciate ligament injuries are due to a non-contact mechanism and usually after hyperextension of the knee (2). It should be noted that these injuries are more often found in women or young adolescents. Indeed, there is a predominant role for female hormones, which induce a more consequent ligament laxity. Research has identified oestrogen and progesterone receptors in the ACL, suggesting a hormonal influence in ACL sprains (3). It is also interesting to note that between 20 and 50 degrees of flexion, the stability of the knee joint is less, as both cruciate ligaments are quite loose, which is why it may be wise to work within these ranges of motion in prevention sessions (1). Regardless of gender and type of treatment (surgical or conservative), cruciate ligament injuries are associated with potential long-term complications, including chronic knee instability, meniscus tears, cartilage damage and the development of osteoarthritis. It is estimated that approximately 50% of affected patients will develop signs of osteoarthritis associated with pain and functional impairment within 10 to 20 years of the initial injury (4). 

What tests should be used for diagnosis ?

Some examples of tests that can be used to try and identify an ACL or PCL injury are as follows, although these tests require the advice and opinion of medical professionals. 

• Lachmann trillat : the most recognised ACL test, it consists of testing the ligament in a flexion situation of less than 30°. Good muscular relaxation of the hamstrings is essential in order not to disturb the test or the clinician’s feeling. One hand is placed on the thigh and the other on the anterior tibial tuberosity and the practitioner then applies a shearing and anterior drawer movement. If the stop is soft and not clear, a ligament injury may be suspected. 
  
• Posterior drawer test : This test is used to demonstrate damage to the posterior cruciate ligament. The patient lies on the table with the knee bent at 90° and the therapist sits on his foot. Both hands are placed on the upper 1/3 of the tibia with the thumbs facing the joint space. He then applies pressure to create a posterior drawer and if the stop is soft, then there is a risk of an injury to the LCPI
  

The tests do not replace the results of medical imaging, an MRI is necessary to validate or not the diagnoses already established. 

And anatomically, what are the cruciates and where ?  

Anatomically, the ACL is a ligament that is inserted anteriorly on the tibia and runs superiorly, laterally and posteriorly to attach to the medial side of the external femoral condyle. In fact, it is itself made up of 2 ligaments, one crossed in a sagittal plane and the other in a frontal plane (Anteromedial/Posterolateral). It is an intra-articular but extracapsular structure with limited healing capacity (2). It should also be noted that it is less well vascularised than the LCPI.

The LCPI is a ligament inserted posteriorly on the tibia and runs superiorly, medially and anteriorly to attach to the medial condyle of the femur. It is better vascularised and also composed of 2 twisted bundles (Anteromedial/Posterolateral).

What about rehabilitation ?

A few notions seem essential in the management of cruciate knee ligament injuries. Firstly, it is important to know that the effects of rehabilitation starting before the operation are no longer debatable. This early rehabilitation, started before the operation, helps to limit and anticipate the consequences of the operation on muscles such as the quadriceps and hamstrings, which are essential for the proper function of the lower limb for movement or balance. Active, supervised, closed-chain strengthening should therefore be applied as soon as possible once the pain has subsided. Proprioceptive work, which is also supervised, has also proven to increase the speed of proprioceptive recovery after surgery. 

When communicating with patients, it is necessary to start with a rehabilitation programme of at least 8 months and to adapt it to the evolution of each patient. For sportsmen, it seems easier to count on a period of 6 months of intensive re-education and then to add 2 months of re-athletisation, while continuing the physiotherapy in parallel. Maturation of the plasty is at 12 months, but we often speak of 3 years for the tendon to be identical to the ligament. 

CAUTION: increased monitoring of all movements and the implementation of safe exercises should be implemented between the 2nd and 4th month. This is the period of ligamentisation, when the tendon graft transforms into a ligament in a natural way. However, this conversion implies a significant fragility of the graft. It is therefore recommended not to perform jumps or proprioceptive exercises too intensively during this period in order not to risk a new injury. 

Throughout this rehabilitation, the work will always be based on the notion of progressiveness, leading to a phase of reathletisation with or without the ball depending on the period and the player’s feelings. The psychological aspect is not often addressed, but positive communication and encouragement can improve the player’s feelings. It is necessary for the player to be aware that the physical and proprioceptive recovery will take time and that it is essential never to rush the process. 

And most importantly, how can cruciate ligament damage be prevented ?

Overall, it has been shown that BMI (Body Mass Index) is a determining risk factor for cruciate ligament injuries but also for knee injuries in general. Indeed, it goes without saying that a heavier person will have a greater impact on the structures of his joint each time he stands or lands. Regarding more specific prevention to protect the knee, it has been shown that a pre-season programme combined with a maintenance programme is very effective (5). This programme should be started about 6 weeks before the intense efforts found during matches if we want to give the body time to evolve physiologically (2). It is not simply a matter of strengthening the stabilisation capacities before starting the season, but rather of continuing the training, so as to maintain the benefits over the long term. 

The most obvious concept is probably the one based on proprioceptive strengthening. However, it needs to be worked on in a precise and varied way in order to prepare the knee to face many different situations. The control of the landing is undoubtedly the point to work on and this by modifying the visual or proprioceptive inputs to the maximum. Thus, it is recommended to perform unipodal, bipodal, open or closed eyes exercises or to disrupt the athlete’s sound inputs with music or additional information. The introduction of imbalance in the propulsion, jumping or landing phase also provides an opportunity to work in depth on the rapid adaptive capacities. Furthermore, Hewett and Myer (6) have shown that the mechanism of non-contact ACL injuries also includes poor trunk control, increasing the importance of also working on trunk proprioception and upper limb position during jumps. On the other hand, trunk musculature and position are also closely related to non-contact ACL injuries because of their influence on hamstring activation (7). The meta-analysis by Gagnier et al. also demonstrated the effectiveness of this neuromuscular training and educational intervention, which appears to reduce the incidence of ACL injuries by approximately 50% (8).

In terms of strengthening, it is important to target the hamstrings primarily as they prevent anterior translation of the tibia by functioning as ACL agonists (5). Nyland et al (9) have also shown that hamstring fatigue leads to deficits in dynamic knee control in the transverse plane, thereby increasing the risk of injury. Gluteus maximus and gluteus medius strength are equally crucial in reducing femoral rotation and valgus of the knee on landing or during changes in direction (10). 

In the literature, many programmes incorporate plyometric exercises into their regimen, representing exercises that alternate eccentric and then concentric contractions of the same muscle. These exercises can be imaged with jumping and repetition sequences. These have been shown to decrease landing forces, reduce hip adduction and abduction moment, increase lower limb strength and decrease the incidence of serious injury (11). Plyometrics can also address differences in leg strength and dominance by rebalancing muscle ratios in a functional manner most of the time. The results of plyometric training programmes confirm and emphasise the role of the hip musculature in dynamic stabilisation and control of the alignment of the lower limb at the moment of ground contact, allowing the quality of landing to be optimised at each stance (12). However, if one or more weaknesses in these muscles are present, then it will be more difficult to stabilise and align the knee with the rest of the lower limb if the hip is flexed, resulting in an increased risk of knee injury. The literature also suggests that increased preparatory activity of the adductors and this adductor-abductor coactivation through plyometrics has been shown to be beneficial in maintaining hip stability. 

Regarding splints or strapping, it is necessary to be careful. If these restraints are only used for preventive purposes, the literature shows inconclusive effects regarding their effectiveness (13). When used in matches or during training, they can certainly limit torsions or rotations slightly, but they can nevertheless reduce sprint speed, increase muscle fatigue and above all reduce internal proprioceptive control over the long term. These decreases in the stabilising capacities of the joint imply effects that are totally contradictory to everything that is proposed during the session to reduce the risk of injury. However, it is important to bear in mind that we are talking here about preventive splints and not those worn after an injury. 

The little extra that changes everything : Good ankle mobility ! 

A particularly underrated concept in the importance of knee injury prevention is good ankle mobility in dorsal flexion. Indeed, a greater range of motion in passive dorsiflexion of the ankle was associated with greater movement in knee flexion. The knee can therefore be more involved in the stability of the lower limb as it can make more effective use of its active stabilisation capabilities. This improved ankle mobility allows the knee to remain in a vertical axis, directly avoiding the risk of injury or slippage. It should also be noted that this increase in amplitude reduces the reaction forces on the ground during landings.  

In addition, the increased extensibility of the plantar flexors associated with this good amplitude of dorsiflexion movements can indirectly contribute to reducing the load on the anterior cruciate ligament (14).

To summarise, improved ankle mobility allows the knee to better absorb stress without the risk of buckling as a result of ankle locking, directly inducing violent, non-knee centred stress. 

References :