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Doctor Joël MIRBEY

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Doctor Frédéric GIVRY

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Gonarthrosis

Definition

Gonarthrosis is defined as the cartilage affection of the knee joint.

The cartilage, a white substance, with a mother of pearl colour, perfectly smooth, covers the extremities of the bones so as to prevent a direct interposition between the bone structures. Soft to the touch, this structure is very resistant to the conditions of physiological use of the joint. The vascularisation of the cartilage and the possibilities of regeneration are bad, which explains why, as soon as there is an injury, the latter becomes final. This affection is shown macroscopically by a rough, abrasive aspect. This aspect can jeopardize the corresponding cartilaginous surface whenever the joint is solicited, particularly by the weight of the body (mirror affection).

Thankfully, most known injuries are very localised and are not prone to worsening.

All injury levels may occur: from very superficial injuries involving a simple crack in the cartilage to major cartilage affections which lead to exposing, i.e. stripping the bone tissue that faces this injury.

The term arthrosis includes all cartilage affections whatever their extent and depth may be.

Symptomatic expression of the most superficial injuries is most often non-existent. However, serious cartilage affections, involving real chondral avulsions on a sometime extensive area, will constantly lead to clinical measures. Superficial affections having functional by-effects necessitate medical treatment. Medical treatment may be suggested for arthrosic affections generating serious discomfort.

 

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Endoscopic view: healthy cartilage

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Endoscopic view: pathological cartilage

Anatomy of the Knee

It is customary to define three spaces or three different compartments at the knee joint level.

We shall speak of the internal compartment, corresponding to the femoral condyle and the internal tibial plateau, of the external compartment, corresponding to the lateral condyle and the external tibial plateau, and of the femoral-patellar compartment (the space situated between the deep side of the patella and the front part of the lower femur extremity).

When a cartilage affection reaches only one compartment, we will use the term uni-compartment arthrosis. For an affection of the three compartments, we will speak of a tri-compartment arthrosis or pangonarthrosis.

Etiology

The causes behind the emergence of arthrosic injuries of the knee are numerous. They are sometimes linked together, thus explaining the occurrence of degenerative injuries that handicap patients who are young and active.

-Post-traumatic arthrosic injuries:
A displaced joint fracture will affect the facing cartilage. This chondral disruption is all the more imporant as the fracture injury is made up of multiple small size fragments. If the surgical intervention was carried out in order to reposition in a perfect way the fragments resulting from the initial trauma, the weak healing capacities of the cartilage will lead to an irregular cartilage tissue, with an abrasive surface, which may inure the facing healthy cartilage.

-bow-legged and knock-knees morphological type: (see knee ligament injuries)
A patient having a bow-legged morphological type is more prone to internal compartment cartilage affections. Thus, in vertical and unipodal position the mechanical constraints connected with body weight and kinetic energy are stronger in the internal (medial) femur-tibia space than in the external (lateral) femur-tibia space. On the contrary, the patient having knock-knees (outside-oriented leg axis) and for the same reasons, will use the lateral compartment more.
In both cases, excess weight increases the arthrosic potential.

-Malposition or femur-patella dysplasia syndrome.
The patella's external shift in relation to the trochlear ring, through which the patella moves, creates excessive constraints on the external part, which may generate arthrosic injuries.

-Chronic ligament laxity (See chapter on knee ligament injuries).
The direct relations existing between knee ligament instability, particularly through hamstring rupture, and arthrosic injuries has already been explained.

-Knee osteonecrosis and osteochondritis.
Such pathologies, which are often of vascular origin, localised within only one compartment, may lead to arthrosic injuries, all the more difficult to treat as they likely to occur in young and athletic patients.

-Synovium chondromatosis and other degenerative synovium pathology.
Such primitive synovium affections, which are thankfully rare, may induce premature gonarthrosis by disrupting joint and chondral metabolism.

-Primitive gonarthrosis.
We talk of primitive gonarthrosis when no specific etiology can explain the occurrence of chondral injuries which sometimes develop rapidly in patients having a previously healthy knee. The notion of family predisposition is often found to exist. Primitive gonarthrosis represents a very high percentage of degenerative injuries necessitating surgical treatment.

Clinical Symptoms

Questioning helps find, as the case may be, one of the etiological factors given in the previous chapter along with its characteristic clinical symptoms. When gonarthrosis is constituted, clinical diagnosis is easy.

Pain constitutes the main symptom. It follows a so-called “mechanical” rhythm. It is quite strong at getting-up time and may diminish once the joint is active then increase again with fatigue. It then transforms into a kind of painful discomfort which gradually imposes a limitation in physical capacities with a reduction in walking space. As pain constitutes one of the determining factors for surgical intervention, it would be good to conduct a rigorous checkup to define its frequency, its intensity, the duration of the attacks, whether it occurs only during the day or permanently, the effects on sleep.

Cracking is constant whenever cartilage injuries are deep. They are caused by bone pieces' coming into contact.

Joint effusion (hydarthrosis) is constantly encountered in well-developed arthrosic injuries. The volume and hence the discomfort linked to the effusion develop along with the physical constraints imposed on the joint.

Joint stiffness is caused by effusion but especially by the altering of cartilage components whose role is to ensure the smooth sliding of bone pieces one against the other with minimal friction. Chronologically, stiffness reaches flexing. The limiting of stretching corresponds to older and more serious affections. Functional discomfort then becomes permanent, since in vertical position the knee can no longer be placed in hyperflexing position (recurvatum). This so-called “lock” position corresponds to leaving the thigh's muscles unused. Joint stiffness is made worse in cases where associated intra-joint foreign bodies are present.

Joint instability is frequently witnessed in cases of advanced gonarthrosis. It is often caused by freely mobile foreign bodies intervening between bone endings while exercising pressure. This instability is also caused by the ligament distensions leading to gonarthrosis. Instability episodes may be strong, accompanied by recurrent falls leading to traumatic injuries at a certain distance from the gonarthrosis (femur head, ankle, shoulder, wrist, ...).

In severe cases of gonarthrosis, the knee looks, when locally examined, constantly misshapen, due to joint stiffness and the proliferation, on cartilage affection areas, of osteophytes. Such bone surface shapes can be easily fingered, especially on the knee's internal side.

Paraclinical Exams

In most cases, diagnosis of gonarthrosis is easy. A clinical exam is sufficient.

The radiological checkup's aim is to define the depth of the injuries and their single or mutli-compartment location. It allows us to explain to the patient, in a clear way, the pathology from which he/she is suffering. Finally, the standard radiological checkup is indispensable in defining the surgical therapeutic strategy.

The NMR examination is useful for diagnosing early injuries, which are sometimes painful and undetected by the standard radiological checkup.

Evolution without any Treatment

Surgical treatment is efficient, leading to a high decrease in pain for early and localised arthrosic injuries. There are many methods which may be used in surgical treatment, of which we may mention the therapeutic arsenal we possess of analgesics, anti-inflammatories, muscle relaxants, physiotherapy, and weight loss.

Be it with or without surgical treatment, knee arthrosis may evolve in such a way as to functionally affect the quality of life, thus necessitating a surgical solution. Such solution's purpose is to improve stability and comfort, but also to reduce chronic medical intake, which has its own complications.

Severe gonarthrosis is always accompanied by a high reduction in walking area (sometimes the patient's autonomous space is reduced to ten metres round). Pain is then constant and affects sleep quality. Joint stiffness in stretching as well as in flexing hinders the possibility of making everyday movements (washing and cleaning oneself, getting dressed, driving a car...).

The situation becomes intolerable when limp walking necessitates the use of crutches or when joint instability leads to recurrent falling.

A better detection of gonarthrosis has now made this kind of scenario rather rare. However, such developments may still be observed when the patient's overall state is no longer compatible with surgical intervention effected in sufficiently secure conditions.

Surgical Treatment

Higher life expectancy rates and improvement in surgical techniques have contributed to the increase in the number of patients who may take advantage of surgical treatment. The way patients are selected for surgical treatment is done based on the effects age, the patient’s overall state, topography and depth of injuries, joint instability while walking and fast aggravation of arthrosic lesions have on everyday life.

This real “stock-taking” is meant to allow for a better definition of the most suitable moment for surgical intervention, so as to optimise the intervention’s results and minimise its risks. A patient who has become tired through constant pain, stiffness, and sedentary activity will obtain less satisfactory functional results through heavier re-education, as compared to the benefits this same patient may enjoy through earlier surgical intervention.

Surgical care for gonarthrosis may be done through conservation treatment (osteotomy involving axial readjustment) or arthroplasty treatment (prosthesis replacement). In the latter case arthroplasty may involve one compartment (single-condyle prosthesis) or the knee’s three compartments (tri-compartment prosthesis) We may also mention the existence of rather rare cases involving the prosthetic replacement of the space between the patella and the femur (femur-patella prosthesis).

Osteotomy involving axial readjustment of the knee’s tibia.
The site where a bone cut may be effected may rarely involve the lower extremities of the femur (bow-leggedness). It most often involves the upper part of the tibia (knock-knees). In this latter case, the bone section is meant to reposition the leg’s axis toward the exterior, so as to reduce mechanical constraints between the femur and the tibia in the knee’s internal part. Indications are most favourable for a young patient having moderate arthrosic injuries that are limited to the internal compartment alone. Intervention is outside the joint. The bone cut is fixed through a device allowing immediate recovery of joint mobility with partial pressure for three or four weeks (staples, compression plate). The operation reduces pressure and hence mechanical constraints at the level of the area affected by the degenerative process. Arthrosis is then slowed down and the pain syndrome reduced (See radiographic pre- and post-op image).

The patient may usually hope, when the fixed installation is good, for a lasting improvement of 10 to 15 years. This technique always offers the possibility of future knee arthroplasty.


Single-condyle arthroplasty (Internal or lateral single-compartment prosthesis SCP)
The surgeon has arthroplasties (prostheses) that may be suitable for reconstituting only one knee compartment (medial or lateral). Intervention is suggested for cases where cartilage structures have disappeared in one single compartment or when there is bone necrosis (osteonecrosis) at the level of the bone tissue situated at the contact zone of the cartilage.

single-compartment or single-condyle prosthesis is meant, in principle, to offset losses in failing cartilage zones through the use of compatible inert components, so as to eliminate the bone contact causing the pain syndrome while conserving joint mobility. This type of intervention, which spares the other knee compartments, is suitable for use in cases where arthrosis spreads all over and calls for later implanting of a so-called total prosthesis (tri-compartment prosthesis).

Intervention is carried out using mini-invasive surgery (MIS). This modern procedure is made possible through suitable instruments making it possible to effect short incisions on the front side of the joint (10 cm).

The prosthesis' shape is so designed as to best replicate the knee joint's physiological conditions as far as mobility and stability are concerned. The types of implants available when the patient is treated outside any excessive stiffness allow us to create amplitudes that are close to those observed in a healthy knee (complete stretching, 130° flexing). The femoral part is made of metallic alloy. The tibial structure is composed of high-density polyethylene over a metal base that is often made of titanium. The prosthesis may be either cemented to the bone or implanted without cementing. In the latter case, the coating that is in contact with the bone is made up of “micro-granules” compatible with secondary re-occupation by the bone tissue. Hydroxy-apatitis coating (micro-crystal structures), which resorbs while at the same time stimulating the implant's bone re-occupation, represents a modern way of anchoring non-cemented prostheses on the bone. Current trends call for the use of non-cemented prostheses so as to ensure durability, all the more so as this type of prosthesis is readily used on patients who are still young.

The surgeon possesses specific instruments allowing him/her to best position the implants, so as to reduce mechanical constraints and optimise joint suppleness.

The operation should also allow for a restitution of a satisfactory axis for the lower limb, so as to maintain harmony between the constraints of the prosthetic and the conserved compartments.

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Photograph: single-condyle arthroplasty implant (internal or lateral SCP)

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Radiography: Installation of a single-condyle prosthesis

Tri-compartment arthroplasty (total prosthesis).
This type of implant is reserved for patients suffering from arthrosic injuries involving the medial and lateral compartments (pangonarthrosis). Such prostheses have a triple purpose : replacing the defective knee cartilage, recovering the physiological axis of the lower limb while improving joint suppleness and stability.

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Photograph: Tri-compartment arthroplasty implant (total prosthesis)

While both cemented and non-cemented fixing is possible, the current tendency is to limit the use of cement, so as to improve the prosthesis life-span. The femoral part is made up of complex metal alloy. The tibial part is made from high-density polyethylene usually fixed to a metal base inserted in the upper part of the tibia. The base may be fixed or mobile. In the latter case, the knee joint may undergo flexing and stretching movements but also tibia rotation in relation to the femur, thus improving comfort while walking and stability. The patellar part is made up of polyethylene, which is sometimes fixed on a metal base.

The design of the prosthetic components is adapted to recovering maximum suppleness of 130° in flexion for full stretching. Such operations are often carried out on knees having serious ligament failure. The implants are also studied in such a was as to compensate ligament insufficiencies on the frontal and sagittal planes.

The intervention generally takes a little longer than the one for single-condyle arthroplasty, but the latter's principles are well-adapted to tri-compartment arthroplasty (mini-invasive surgery, applying pressure immediately after the intervention, starting re-education and seeking to recover mobility the day after the intervention).

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Radiography: pathological joint

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Radiography: tri-compartment arthroplasty (total prosthesis)

Such interventions may be carried out under general anaesthetic or under local-regional anaesthetic (spinal analgesia). Anaesthetic Pre-op consultation, which should legally take place several days before the intervention, is meant to define the type of anaesthetic most suitable for each patient.

The introduction of mini-invasive surgery and the possibility of making such interventions without post-op drainage have contributed to reducing significantly the in-stay period for this surgery (4 to 8 days). Efficient care for pain has contributed to improving prosthetic intervention results, thus allowing for early and active re-education, which is necessary for optimising eventual joint suppleness.

Pain-care methods depend on the type of intervention, the patient, the patient's medical history, and the preferences of the anesthetist and surgeon. Pre-anaesthetic consultation helps explain to the patient the modalities concerning post-operation pain-care.

Be they cemented or non-cemented, modern arthroplasties are compatible, in the majority of cases, with applying full pressure on the operated limb the day after the intervention. Walking is to be secured with crutches. Some surgeons recommend the use, for a few days, of a removable knee splint, others advise against it.

Regaining flexion is done through early daily re-education, which may be either manual or controlled electrically. The flexing progression curve varies according to various factors. Reaching 90° flexing on the 4th post-op day constitutes a guarantee, as regards obtaining permanent optimal flexing according to the prosthesis' mechanical specifications (120 to 135°).

Many surgeons have integrated into their protocol the detection of any possible vein complications, carrying out systematically doppler-graphic examination so as to best adapt the preventive anticoagulant treatment. Improvements made to the technical conditions of arthroplastic surgery has led to a decrease in the percentage of patients sent to re-education centers on leaving the clinic.

Incapacity and rehabilitation

  • Total temporary incapacity varies from 2 to 4 months, depending on age, the type of intervention, the knee's medical history, and re-education conditions.

 

  •  Good evolution corresponds to recovering a permanent amplitude of 80% in 6 weeks, the final amplitude may only be definitively reached in the 6th month after the intervention.

 

  •  Heat felt in the operated knee disappears between the 6th and 12th months.

 

  •  The patient stops using crutches between the 3rd and 5th weeks.

 

  •  Daily re-education is best followed at home with a physiotherapist for a period of 2 to 3 months.

 

  •  Driving may be resumed on the 30th day after the intervention.

 

  •  The patient can walk freely without any limits imposed.

 

  •  Non-violent sports are allowed. Cycling and swimming are recommended. Such activities help the knee muscles recover.

 

  •  Anticoagulants are stopped on average on the 30th post-operation day.

Complications

We will first mention, in ascending order of seriousness, temporary and banal post-operation clinical symptoms, and then consider complications related to the prosthetic surgery of the knee.

  •  Joint effusion:

It is constant in the first weeks and will most often disappear on the 30th day. If it is strong, it will delay flexing recovery and will have to be punctured.

  •  Inflammation around the joint:

It is usual to have inflammation accompanied by an increase in knee skin temperature – it is a sign of healing and does not indicate the presence of an infection, especially if this inflammation constitutes an isolated symptom.

  •  A feeling of knee “ankylosis”:

It is usual, in the first weeks following the prosthetic intervention, that walking again after a long period of inactivity be accompanied by a feeling of ankylosis or loss of mobility. Whenever this impression may be experienced, it most often disappears in the 3rd or 4th month after the operation.

  •  Post-op joint stiffness:

Its occurrence has been quite a bit reduced thanks to improving techniques. Objective evaluation of stiffness is still difficult. It depends on the pre-operation condition of the knee. It is considered problematic if after a period of normal amplitude recovery, the patient starts losing the stretching and flexing they have regained. In some rare cases, it is possible to recommend joint remobilisation under analgesics, so as to avoid the constitution of an irreversible inter-joint adherence process.

  •  Algo-neuro-dystrophy syndrome:

It emerges sometimes early and is characterised by a hot hyperalgesic knee. It may severely hinder re-education conditions and lead to joint stiffness. Once it has been confirmed by radiographic and scintigraphic examinations, algodystrophy syndrome must be specifically treated using suitable re-eduction and possibly hormone therapy, with the aim of regaining the metabolism regulating calcium incorporation on the bone tissue.

  •  Thromboembolic complications:

They may occur for all surgery involving a lower limb. They may be detected and prevented through post-operation doppler-graphic exams. They are most often benign, but may alter the final result by slowing down re-education.

  •  Infectious conditions:

Two clinical pictures may be observed:

  • * Early post-operation septic arthritis is fortunately rare. The reliability of sterilisation procedures, the use of disposable devices, making passages that are first short, and abundant rinsing during the operation, as well as helping patients be more prepared all constitute factors that help limit risks of infection. If such complications do occur, the responsible germ must be identified, antibiotic therapy adapted to the germ must be set up, and sometimes surgical re-intervention may be necessary.
  • * Latent infections: a prosthesis implanted in perfectly aseptic conditions may be subject to secondary contamination through an area located at a certain distance (pharyngitis, abscess, whitlow, dental infection, urinary infection, ....). Be it a septic grafting on an initially clean prosthesis or a latent initial infection, a new intervention is not an obligation. Suitable antibiotic therapy, once the responsible germs are identified, may lead to the patient's recovery. A long medical and biological follow-up is indispensable.
  •  Loosening of prosthesis:

systematic radiological follow-up or the emergence of chronic pain may reveal a loosening of the implants off the bone structures. A loosening edge may appear through radiology. The loosening may occur without infectious complications or as a consequence of an infection of the prosthesis site. A new intervention is usually necessary in order to solve this problem.

  •  Joint instability when walking.

In cases of serious ligament deterioration, the knee may become unstable when the person walks. Specific prosthesis models, which are currently available, offset ligament weakness and improve the patient's comfort (prosthesis with a hinge, reconstitution prosthesis).

  •  Chronic knee pain:

In such cases, the patient notices real improvement after the intervention, but the knee remains chronically in pain, and the clinical check-up and radiological follow-up do not reveal anything. It is then advisable to look for either an algodystrophy syndrome or an underlying infection. A small percentage of knees continue to hurt without any apparent reason.

  •  Intolerance toward the implanted materials (Nickel): it occurs much more rarely. Pain, joint swelling and pseudo-inflammatory aspects may constitute symptoms indicating such intolerance to implanted materials.

Results

The increasing number of prostheses implanted bears witness to the effectiveness of surgical treatment of severe gonarthrosis.

Results are analysed in terms of the patient's comfort level, but also in terms of the reduction in medicine intake (analgesics, anti-inflammatories), whose risks cannot be underestimated.

- In cases of a pathology limited to one joint, arthroplasty will lead to an end of analgesics and anti-inflammatories intake.

- Joint amplitudes increase by an average of 20% compared to the post-operation situation. Hence, a knee which had a post operation flexion of 90% should regain after re-education amplitudes of 115 to 120°.

- Reduced pain and increased objective knee stability lead to improving the patient's walking ability and autonomy (which has a positive effect on the cardiovascular system).

- Patients may most often resume driving on the 30th day after the operation. Non-violent sports (swimming pool, cycling, hiking...) are authorised from the 2nd post-operation month. Violent sport activities are not recommended, mostly because of risk factors concerning prosthesis fracture.

- Eliminating chronic and insomnia-related pains will help improve the patient's psychological condition.