The knee joint is made up of so-called “crossed” lateral and central ligaments. The lateral ligaments, containing a good number of veins, have very few problems forming a scar when involved in a sprain mechanism.
Unfortunately, things are different with crossed ligaments, particularly the hamstring, for which breaking, when it comes to adults, is final with typical mechanical consequences for the knee joint kinematics.
Crossed ligaments occupy a central position within then knee joint. They unite the tibia below to the posterior part of the intercodylian femur line above. Because of their inverted orientation, they were named crossed ligaments by the early anatomists who described them. The hamstring (ACL) is the most anterior. The posterior cruciate ligament (PCL) is situated furthest behind.
Knee joint diagram
As crossed ligaments are made up of very resistant elastic fibers, they play a stabilising role in the knee joint, particularly on the sagittal side (antero-posterior) and depending on leg's rotation axis vis-à-vis the femur.
The vascularisation of the hamstring is fragile. The situation within the joint explains why in cases of mechanical stress, it is often the “all or nothing” law that applies. The ligament breaks completely, as partial breaking is unfortunately rare.
Hamstring rupture leads to excessive anterior mobility of the tibia, as compared to the femur, associated with an amplification of knee rotation about the leg axis (hypermobility of external compartment).
It is easy to imagine how this situation will lead to a new distribution of mechanical constraints in areas for which the knee is not prepared. To the mechanical constraints related to body weight are added those induced by the kinetic energy of movement, even more so in sports.
Another static mechanical factor must be taken into consideration: the global lower limb axis. Thus in cases of genu varum morphology type (knees remaining separate when heels are in contact) the pressure exercised on the knee's internal part, which is naturally stronger, is increased through the rupture of the hamstring. In this case, and even in the absence of intense athletic activity, the demands of everyday life, such as prolonged walking or standing straight, expose the knee to an internal cartilaginous affection.
An initially isolated ligament affection will become more complex through meniscus and cartilage injuries. When certain sport activities are not stopped sprains will recur and accelerate the above-mentioned anatomical effects and hence the arthrosic process.
Rupture of the posterior cruciate ligament (PCL) leads to a recoiling of the higher extremity of the tibia vis-à-vis the femur as well as to axial destabilisation, but less than for a case of ACL rupture.
The anatomical characteristics of PCL can explain why this ligament's ruptures (a lot rarer than those of ACL) rarely call for a surgical solution.
the quasi constant character of total ruptures can explain why, as soon as an injury occurs, the joint becomes the locus of final modification in the distribution of mechanical constraints to be absorbed.
Endoscopic view: healthy hamstring
It may be deduced from an analysis of the anatomical elements considered above. The ultimate evolution is arthrosic knee decompensation.
This development depends on the frequency and intensity of instability episodes that the knee is made to go through, particularly within the framework of athletic activities. The movement that is damaging to the knee is the same one that generates ACL rupture. It is called VFE (valgus, flexion, external rotation) and combines joint flexing, external leg rotation and the knee's moving inward in relation to the hip-ankle axis.
Continuing sport activities that may reproduce these problematic movements (VFE) with unipodal pressure will induce the same feelings of instability, named “new sprains”.
Sudden changes in direction accompanied by pivoting movement with pressure on the injured limb will accelerate the injuries mentioned in the anatomy chapter and will create new ones (distension of lateral ligaments and peripheral capsular structures causing chronic laxity).
It is often said that injuries evolve like “oil spots”, which explains why the meniscus is thus often affected. It is advisable to tell patients suffering from hamstring rupture and having opted out of surgical treatment to choose sport activities that do not involve potential VFE movements (walking and jogging on flat terrain, bicycling).
- The patient's age at the time of the initial trauma.
The younger the patient is when the hamstring rupture occurs, the higher the degenerative potential (chronic knee pain).
- The patient's weight.
Excess weight constitutes a major negative factor.
- Arthrosic decompensation and morphological type of lower limbs.
In cases of hamstring rupture, the patient having a constitutional morphological type characterised by bow-leggedness is exposed to higher risks of arthrosic development on the knee's internal part (excessive mechanical constraints). On the other hand, a patient possessing an inverted morphological type (the ankle is exteriorly situated in relation to the knee = knock-knees) is more protected from arthrosic affections.
Continuing strenuous sport activities involving pressure on the unstable member, accompanied with sudden changes in direction, favour the reproduction of sprain episodes. Such joint failures, which patients call “little sprains”, lead to gradual distension of the knee's joint capsule and secondarily to cartilaginous affections (gonarthrosis).
a – Acute injury
Questioning will reveal the circumstances of initial trauma, which is often linked to sports. The first episode involves a knee positioning in an extreme VFE situation (see chapter on spontaneous development).
Most commonly, the patient feels a kind of crack and a dislocation or lateral shift of the knee, followed by “reintegration”. Sometimes, the injured person will go through similar instability when exercising leaning pressure after the accident.
The pain, which is of variable intensity, is accompanied by a sensation of inter-joint heat and swelling. The latter may be discreet, in which case it will only be noticed in the hours following the trauma. In cases of athletic injuries, the person concerned has to leave the field. Limping is constant.
joint effusion may have been punctured. A haematic liquid may then probably indicate ligament injury.
Local knee examination will confirm the pain topography, the joint effusion (hydarthrosis or hemarthrosis). In the absence of extreme pain, we are able to administer determining clinical tests (pathognomonic) to analyse the ligaments and find out if the hamstring is injured. The tests in question are “Lackman” (a study of the tibia's front movement in relation to the stretched femur) as well as the “jerk-test” or “pivot shift” (analysing excess mobility of the knee's exterior part in relation to the internal compartment). This second test seeks to reproduce the sensation of instability or dislocation the patient went through in the course of the first injury. This test is often difficult to reproduce because of the apprehension the patient may feel towards it.
b – Chronic injury
In such cases the clinical examination is generally simpler, since the pain is less intense. The patient seeks a consultation for a sprain episode. In fact, the questions asked will allow us to connect this instability episode to an initial trauma, which is sometimes very old and may have even been forgotten by the patient, but which is undeniably the starting point of the ligament pathology that caused the patient to seek a consultation.
Local examination can confirm the Lackman test as well as the jerk-test. Such examination looks for signs of chronic laxity complications (meniscus syndrome, early degenerative injuries).
- A conventional radiological checkup will be carried out in order to analyse the morphological type (bow-leggedness, knock-knees) and to look for early arthrosic injuries.
- An NMR exam may be prescribed if clinical analysis is made difficult, especially because of the pain's intensity or the knee's partial lock. This exam is meant to look for meniscus injuries associated with a cartilage affection.
In the chapter on anatomy, we explained the reason why a rupture of the hamstring exposes the knee to harmful development through final and irreversible modification of the joint kinematics.
The constitution speed of degenerative affections in the absence of treatment depends on the main etiological factors we have mentioned and especially on the frequency and the intensity of instability episodes linked in particular to continuing unsuitable sport activities. Such episodes will lead to a real “joint dislocation” on the ligament level, thus making the surgical treatment which may have been possible at first inefficient or even dangerous (making arthrosic risks possible).
It is then important to give the patient clear and objective information, be it on the diagnosis or the prognosis of this affection. When the injured is in possession of this information, they may make their therapy choice (medical treatment or surgical treatment), keeping in mind that the odds of a successful surgical treatment decrease as the illness gets older and distant ligament injuries appear.
If a surgical option is chosen, the patient, while awaiting surgical intervention, must avoid exposing his/her knee to other instability episodes by choosing specific sport activities. Such activities are always recommended, particularly if their purpose is to regain muscular strength in the injured lower limb.
Medical treatment can never lead to regaining knee stability in the anatomic sense of the word. This does not mean, however, that all patients having crossed ligament rupture should be treated.
The surgical option depends on the patient's wish to play again his/her favourite sport, the functional discomfort felt and the long-term degenerative potential.
The progress made in knee kinematics knowledge helps explain historically the increase and diversity of surgical techniques which have been proposed for 50 years now in order to deal with hamstring ruptures. Modern surgical techniques share increasing similar principles. The number of proposed interventions can be explained by the graft used to offset the lost ligament. We offer here, for didactic purposes, some consensual points regarding the repair of the knee's hamstring.
As a preamble, we must insist on the objective information the patient must receive before undergoing ligament repair (ligamentoplasty). This information must include a real “state of affairs” concerning the injured knee, particularly taking into account the morphological type, the rupture's isolated or complex character, the possible associated meniscus or cartilage injuries, mechanical (excess weight) or sport constraints placed on the joint. The patient will receive an explanation of the technique chosen by the surgeon, post-op constraints concerning professional and athletic incapacity, planning for rehabilitation (re-education).
Thus informed by the healthcare team, the patient is able to make an informed decision.
We may assert, with no special risk, the existence of a kind of consensus on the following points as regards modern knee ligament surgery:
-Sutures or reinsertion of early ACL ligament injuries never give satisfactory results, because of the devascularisation accompanying the initial trauma linked to the hamstring's anatomical conditions. Such techniques, which were used regularly twenty years ago, have now been almost totally abandoned.
-Hopes based on “artificial ligaments” are disappointing. Such implants are not sufficiently similar in texture in configuration to the natural ligament. Artificial ligaments are exposed to premature ruptures due to their rigidity. They sometimes lead to chronic inflammatory reactions of the synovium which may make re-intervention necessary in order to carry out an ablation.
-Autologus grafts (patella tendon, ACL) are preferred to artificial ligaments as they are not rejected and are quite resistant.
-Arthroscopy seems to be the most appropriate means for positioning the graft in the joint in the best possible way. This positioning which is called “isometric” aims to avoid abnormal use of the ligamentoplasty thus giving it a longer life. Isometry helps recover amplitudes thanks to constant and non-excessive tension on the graft, from stretching to complete flexing of the knee. Arthroscopy has also the advantage of making a precise checkup of the knee joint (treatment of associated meniscus or cartilage injuries). Joint endoscopy allows for carrying out ligamentoplasty through so-called “mini-invasive” surgery, giving more favourable conditions for quick functional recovery.
-The new ligament's tibial and femoral anchoring devices can most often be dissolved, thus avoiding the stress of possible re-intervention in order to ablate the fastening material.
-In some cases of high peripheral capsule and ligament distension (old chronic laxity), a so-called “extra-joint” plasty will be associated to the repair of the hamstring within the joint. This technique's aim is to limit abnormal mobility within the external compartment and to significantly improve comfort thanks to an increase in joint stability.
Endoscopic view: Hamstring injuries
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Endoscopic view: Kenneth Jones type Ligamentoplasty
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Ligamentoplasty techniques used in endoscopy have led to reducing very significantly stay-in periods (2 to 3 days). Post-operation pains have been reduced thanks to the much less invasive character of the surgical techniques involved (short incision, with no subcutaneous detachment). Such techniques are compatible with the non-use of post-operation draining. Many anaesthetist teams choose to carry out femoral and sciatic nerves (crural) blockade so as to manage post-operation pain in the best possible way.
Some techniques allow for immediate post-op pressure, walking is then done with the help of crutches during the first two weeks. Using a removable splint depends on the surgeon's usual preference.
Depending on the patient's professional activity, temporary total incapacity may vary on average from 6 to 12 weeks.
- Driving may be possible after the 3rd post-op week.
- Re-education is to be followed daily for the first 6 weeks. Mini-invasive surgical techniques have led to simpler re-education procedures, by reducing painful phenomena and scar inflammation processes. Re-education is best conducted at the physiotherapist's practice.
The physiotherapist will try to make the patient, regularly and gradually, recover joint flexing amplitudes and reach complete amplitudes in 6 to 8 weeks, with an intermediate stage of 80° flexing in the 3rd week and 110° to 115° on the 30th day. Postures will be realised to avoid the constitution of a flexum (inability to regain complete knee stretching). Massages, physio- and hydrotherapy will be used to decrease inflammatory reactions and to relax the muscles so as to increase amplitude. Regaining muscle strength and proprioceptive senses most generally occur after the first post-op month. The physiotherapist will explain to the patient the exercises he/she must personally make several times a day, so as to improve the active knee structure, easier walking and subjective joint stability. The following functional gains maybe be considered as proof of good evolution: abandoning crutches in the 2nd post-operation week, walking without limping on the 30th day, acquiring 80% of flexion on the 6th post-operation week, absence of limitations on stretching on the 30th post-operation day, resuming swimming activities on the 30th post-operation day, cycling on the 45th post-operation week.
- Resuming sport activities is most often possible at the end of the 2nd post-operation month. Such activities must be selective and gradual, giving preference at first to swimming, cycling, jogging on even and stable terrain. Sports involving sudden changes in direction and pressure on one foot may be started as soon as the injured person has regained essential proprioceptive senses and all amplitudes. Resuming involvement in competitions may occur on average, and depending on the kind of sport practised, between the 3rd and 6th post-operation months. The higher post-operation loss is, the longer the regaining of muscular mass volume in the operated member will take. The speed at which recovery occurs depends directly on the efforts the operated person will personally make by following the exercises taught by the physiotherapist. The patient may feel that his/her knee is more or less stable, when it is perfectly stable on the ligament level but has insufficient muscular sheathing. Increase in strength and muscular volume is always accompanied by an improvement in the operated joint's subjective stability.
Complications may be involved when ligament reparis is carried out in the context of an isolated injury, particularly when no associated cartilage affection occurs.
In ascending order of gravity, we may mention:
Persistent joint effusion:
It may lead to residual pains and hinder the regaining of flexing amplitudes. Such effusion is part of the normal and usual scar inflammatory reactions. Such reactions usually disappear at the end of the 2nd post-operation month, thus leading to a gradual drying up of the joint. The strongest effusions, which limit flexing, may be evacuated through puncturing. In some cases, joint effusion may last several months (4 to 6) and lead to rejection of the graft's grafting materials within the joint.
Sensitivity and inflammatory reactions in the graft removal area: mini-invasive surgery has greatly limited the frequency of such symptoms which, in extreme cases, may last 8 to 12 months. Such reactions do not usually hinder active re-education. Similarly, skin sensitivity on the front side of the side may be experienced for one year, particularly when kneeling down.
Post-operation joint stiffness:
This is a rather rare complication when the knee has been perfectly prepared for ligamentoplasty and presents no amplitude limitation before the intervention. However, post-operation pains in patients with anxious temperament may delay amplitude recovery as compared to the ideally planned evolution. In such cases, re-education lasts longer with an emphasis on muscular stretching and stretching and forced flexing postures . It is usually considered that on the intervention's anniversary, amplitudes that have not been regained will permanently disappear.
When flexing is limited to just a few degrees, no effects will be felt on athletic performance. However, if a small stretching deficit (flexum) continues, it may have functional consequences leading to the interruption of some sport activities.
Non-complicated post-operation stiffness, as an algodystrophy syndrome, may, in rare cases, call for an intervention to mobilise the joint, under general anaesthetic, so as to effect a rupture of the adhesive scar which has caused the stiffness. Such intervention will lead to conserving joint amplitudes only if it is followed by immediate willing and active re-education.
It involves the occurence, in the weeks following the intervention, of pains most often hindering re-education and thus generating amplitude limitation that are sometimes of major strength. The knee is then hot and the skin hypersensitive when touched. Radiological check up may substantiate specific demineralisation signs, as scintigraphy confirms bone hyperactivity as compared to a healthy knee. The occurrence of algodystrophy syndromes has been highly reduced through the absence of post-operation immobilisation. However, the un predictable occurrence of such complication can at best delay the awaited eventual condition and, in worst cases, lead to a painful, amyotrophic knee ankylosis, with little resistance to effort.
Treatment of algodystrophy remains medical. Any intervention, even if it is carried out long after recovery, remains uncertain as to the expected functional results, since algodystrophy syndrome may always return.
Persistant post-operation pains:
Some knees may stay in pain long after intervention and with no obvious clinical symptoms indicating complications (latent infection, algodystrophy, inability to tolerate grafting materials, cartilage affection of one or several knee compartments). Such rare cases pose problems concerning the resumption of professional or sport activities in acceptable conditions.
They may be observed in all lower limb surgeries. Modern surgical techniques, thanks to their being compatible with exercising immediate pressure on the limb and with no long-term immobilisation, have greatly limited the occurrence of such complications. Anticoagulant treatment is systematically prescribed after intervention. It is adapted to the patient's possible personal and familial medical history.
Early post-oeration septic arthritis cases are quite rare. The good reliability of sterilisation processes, the use of disposable devices, the making of short pathways at first, and the thorough washing of arthroscopic joints, all contribute to limiting risks of infection.
Infectious complications are often the consequence of certain predispositions. We may emphasise the negative role of diabetes, of underlying arteriopathy of the lower limbs, and chronic tobacco addiction.
The occurrence of such complication will lead to heavy medical and sometimes surgical care. It constantly tarnishes the eventual functional results.
If instability is associated to locking episodes linked to meniscus affection, such episodes will disappear thanks to the treatment administered at the time of arthroscopy.
Repair of the failing cruciate ligament will lead to regaining a stable knee, i.e. to the disappearing of the insecurity episodes that have led the patient to seek therapy.
It is important to remember that subjective stability will not be really reconvered until the patient has regained muscular mass on the operated side that is equivalent to the healty one's.
If intra-joint plasty has not been ideally positioned, it may undergo abnormal mechanical constraints which may lead to its distension, or even a new rupture. An optimal positioning of the new ligament, undertaken under endoscopy, will limit in a major way this unwanted development.
We should emphasise that repairing a ligament does not mean that a recurring rupture is out of the question, even if the quality of the ligamentoplasty is perfect. Indeed, a trauma felt on the operated joint which is of the same nature as the one that has caused the first accident will obviously have the same effect on the ligamentoplasty. Such incident does not indicate a kind of defect in the technique but an unfortunate etiological event that may lead to re-intervention.
It is possible for patients who are athletes and have an ligament injury that is isolated or associated to simple meniscus affections to resume sport activities. The faster the lower limb's muscular strength is regained the faster will resuming sport activities be possible. Personal motivation constitutes a determining factor as to the patient's aptitude to fin the pre-injury performance level.
In cases where results, on the functional plane, are considered insufficient by the patient, as soon as the knee objectively reaches stability, it is logical to expect a decrease in the longterm degenerative potential through the stabilising intervention that was carried out.