Joint endoprosthetics

Joint endoprosthetics is considered one of the most effective methods of surgical treatment of patients with rheumatological diseases. This operation has become an integral part of the rehabilitation treatment of patients with rheumatic pathology and musculoskeletal disorders, since it not only relieves pain, but also restores functional activity and improves the quality of life.

The relevance of this method of surgical treatment is due to the frequency and nature of joint damage. In more than 60% of patients with rheumatic diseases, the joints of the lower extremities are involved in the process. Clinical or radiographic signs of hip joint damage are detected in 36% of patients with rheumatoid arthritis, and the average age of patients at the time of surgery is 42 years. Joint endoprosthetics is also necessary for 5-10% of patients with systemic lupus erythematosus in the event of aseptic necrosis of the femoral head, most often bilateral. This process usually occurs at a young age, it is accompanied by severe pain, limited movement and decreased functional activity.

In the USA, juvenile rheumatoid arthritis is diagnosed annually in 100 thousand children, and the hip joint is affected, according to various authors, in 30-60% of these patients. The decrease in functional activity that occurs with this pathology leads to serious psychoemotional problems in children and adolescents due to their forced isolation and dependence on outside help.

In this regard, rheumatoid arthritis, juvenile chronic arthritis, SLE, ankylosing spondylitis occupy a leading place among indications for joint endoprosthetics.

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Indications for the procedure

The purpose of joint endoprosthetics is to restore the functions of the affected limb. This is achieved by eliminating pain and increasing the range of motion. By restoring the functional state of the patient, the main purpose of joint endoprosthetics is fulfilled - to improve the quality of life. This is especially important for patients with RA, SLE, juvenile chronic arthritis, since most of them are young people of working age, for whom returning to a full active life is the key to successful treatment.

When determining indications and contraindications for joint replacement surgery, the following factors must be assessed:

• intensity of joint pain:
• the degree of severity of functional disorders;
• changes in X-ray examination data;
• information about the patient (age, gender, nature of previous surgical treatment, somatic condition).

When determining the treatment tactics, the stage of the pathological process is of decisive importance. The main clinical sign of damage to the articular surfaces is the severity of pain. In this case, pain is accompanied by corresponding functional disorders and radiographic signs, which are most pronounced in the final stages of the disease. Often, when examining patients, a discrepancy is found between the clinical picture and the severity of radiographic changes. In this case, it is much more difficult to justify the need for surgery. In this situation, the leading criterion for determining indications for joint endoprosthetics is the intensity of pain. However, with RA, increased pain may indicate an exacerbation of the disease. All this requires a comprehensive examination of patients in a specialized department, and surgery should be performed at the remission stage.

Impaired limb function due to damage to the articular surfaces, along with the severity of pain, is considered one of the main indications for joint endoprosthetics. In this regard, quantitative assessment systems are important, allowing changes to be presented in points.

One of the most common systems for assessing the functions of the hip structures is the Harris assessment system. If the score is less than 70, hip replacement with an endoprosthesis is indicated.

The most common system for assessing the condition of the knee is the system described by Insall, which includes a characteristic of the pain syndrome and walking parameters. In addition, the functions of the most affected articular surfaces and the degree of limb deformation are assessed. It should be noted that these methods allow not only to assess the functions before surgery, but also the results of joint endoprosthetics in the early and late postoperative period, as well as the dynamics of recovery and stabilization of the musculoskeletal function.

In addition to the above, there are other approaches and methods that allow for a quantitative assessment of the state of the musculoskeletal system. In this regard, it is advisable to use several approaches to obtain a more comprehensive assessment of functions.

Currently, the patient's age is not considered a criterion determining the possibility of joint endoprosthetics. More important is the assessment of the patient's somatic condition, his activity, lifestyle, needs, and desire to lead an active life.

Thus, the following indications for joint endoprosthetics can be identified.

• Severe pain syndrome with impaired limb function when conservative treatment is ineffective and radiological changes are detected.
• Osteoarthritis III-IV radiographic stage.
• Damage to the hip or knee in rheumatoid arthritis, juvenile chronic arthritis, AS and other rheumatic diseases with radiologically detectable bone-destructive changes.
• Aseptic necrosis of the femoral head with progression of head deformity.
• Aseptic necrosis of the condyles of the tibia or femur with progressive valgus or varus deformity of the limb.
• Changes in the hip joint with radiographic signs of protrusion of the acetabulum floor.
• Clinically detected shortening of the limb on the side of the affected articular surfaces in combination with radiographic changes.
• Contracture caused by radiologically detectable bone-destructive changes.
• Fibrous and bony ankylosis.
• Post-traumatic changes that cause a disruption of the support function and the development of pain syndrome.

Indications for endoprosthetics of the metacarpophalangeal joints are:

• joint pain that does not respond to conservative treatment;
• deformation in the metacarpophalangeal joint:
• subluxation or dislocation of the proximal phalanges;
• ulnar deviation that persists during active extension;
• detection of second-degree or higher destruction according to Larsen during radiological examination;
• formation of contracture or ankylosis in a functionally disadvantageous position;
• functionally disadvantageous arc of motion;
• unsatisfactory appearance of the brush.

Preparation

During preoperative preparation and postoperative care of patients with rheumatological diseases, orthopedists face a number of problems related to:

• systemic manifestations of the underlying disease;
• taking DMARDs;
• anesthesiological difficulties;
• technical difficulties:
• concomitant osteoporosis;
• simultaneous damage to many articular surfaces.

One of the systemic manifestations of rheumatic diseases is anemia. Even long-term treatment in the preoperative period sometimes does not give tangible results. An indispensable condition for joint endoprosthetics is the transfusion of an adequate amount of plasma and red blood cells during and after the operation, as well as reinfusion of one's own blood.

Cardiovascular disorders are more common in patients with rheumatoid arthritis than in patients with osteoarthritis. Therefore, in rheumatoid arthritis, a more thorough examination of the cardiovascular system is necessary to determine the surgical risk and conduct adequate preoperative preparation.

When planning a surgical intervention, it is necessary to take into account the medications taken by the patient. There is no convincing data on the negative impact of DMARDs, such as methotrexate, leflunomide, TNF-a inhibitors, on the course of the postoperative period. However, due to the toxicity of these drugs, as well as to reduce the risk of infectious complications, in most cases they are discontinued 1 week before surgery and for the entire period of wound healing.

With long-term use of glucocorticosteroids, atrophy of the adrenal cortex is observed, so such patients need careful monitoring during surgery and in the early postoperative period. If necessary, pulse therapy is performed.

Difficulties in anesthesia are associated with the peculiarities of the course of rheumatological diseases. For example, in juvenile rheumatoid arthritis, damage to the temporomandibular joints in combination with micrognathia can significantly complicate intubation and hinder the restoration of breathing after intubation. The cervical spine is affected in 30-40% of cases of rheumatoid arthritis. Usually the process is asymptomatic, but due to the rigidity of the cervical spine, difficulties with intubation often arise. In patients with instability of C1-C2, there is a risk of damage to the respiratory center during manipulations with the neck during intubation. Difficulties in performing spinal anesthesia may arise due to damage to the spine, ossification of the vertebral ligaments, for example, in patients with ankylosing spondylitis.

Given the multiple lesions of the articular surfaces in rheumatological diseases, a thorough examination of the musculoskeletal system and functional state is considered very important in order to determine the patient's ability to use additional support in the postoperative period. In case of lesions of the shoulder, elbow or wrist joints, patients may have problems using crutches. In such cases, it is often necessary to perform operations on the joints of the upper limbs first. Large articular surfaces of the upper limbs, such as the shoulder and elbow, are less often fitted with prosthetics. In case of pain in the shoulder joints, it is necessary to eliminate the pain as much as possible so that the patient can use additional support.

Patients with multiple lesions of the musculoskeletal system usually experience pronounced atrophy of the muscles of the upper and lower extremities, both as a result of the pathological process itself and due to limited mobility and adynamia. In addition, the soft tissues surrounding the joint are often involved in the pathological process. Damage to periarticular tissues means that the mobility and range of motion achieved in the operated joint are often less than would be expected with this type of surgical treatment. Involvement of many articular surfaces in the process often leads to the development of contractures, subluxations and stiffness, which complicates the implementation of restorative functional treatment. In this regard, the participation of an experienced physical therapy specialist in rehabilitation is of great importance.

Evaluation of radiographs is considered a necessary stage of preoperative planning. Based on the radiographic images of the joint elements, the type of endoprosthesis is selected, the size of its elements is determined, and the stages of surgical intervention are planned. In addition, radiographic examination, along with other methods, allows determining the indications for cemented or cementless joint endoprosthetics. When evaluating radiographs of the hip joint, the shape of the femur, the medullary canal of the femur, the acetabulum, the degree of protrusion of the acetabulum bottom, the severity of dysplasia of the elements of the articular surfaces are taken into account, and radiographs of the knee - the relationship of its elements, the degree of bone destruction of the condyles, the severity of the deformation.

Technique joint replacement

Hip replacement

For the surgical intervention, the patient can be placed on his back or on his side. The surgical approaches are different, but the most commonly used and considered most typical are the anterior-external and posterior approaches. In the first case, the surgical intervention can be performed with the patient placed on his back or on his side. When using the posterior approach, the patient is placed on his side.

During surgery, careful hemostasis is necessary due to anemia as a systemic manifestation of the underlying disease, as well as the undesirability of performing blood transfusions in these patients.

An important stage of the operation is considered to be the test reduction of the hip and assembly of the endoprosthesis unit. In this case, the conformity of all elements of the endoprosthesis to each other, their stability, the correctness of the anatomical orientation of the elements relative to each other and the body axes, as well as the range of motion, are checked, and a dislocation test is performed. Only after this is the final installation of the femoral component and the endoprosthesis head performed.

Knee joint endoprosthetics

Joint endoprosthetics are performed with a pneumatic tourniquet on the hip. Parapatellar access is used (external, more often internal). An important stage of the operation is the removal of pathologically altered synovial membrane, which supports inflammation in the articular surfaces and the development of bone destruction. Preserved pathological synovial tissue can cause the development of aseptic instability of the endoprosthesis component.

The technique of installing resection templates, subsequent selection of the necessary components of the endoprosthesis and their placement are considered typical for this operation. The differences are due to the design features of various models and types of endoprostheses.

It is very important to achieve balance of the knee ligament apparatus during joint endoprosthetics surgery. The valgus deformity that develops with rheumatoid arthritis leads to insufficiency of the internal ligament complex of the knee. In this regard, to achieve a good result during surgery, it is necessary to assess the condition of the ligament apparatus and fully balance it.

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Endoprosthetics of the metacarpophalangeal joints

When performing joint endoprosthetics, most patients use a transverse approach in the projection of the heads of the metacarpal bones. At the same time, the most important thing in the operation of endoprosthetics of the metacarpophalangeal joints is not the placement of the implants themselves, but a complex of interventions on the soft tissues surrounding the joint. To eliminate synovitis, synovectomy must be performed without fail.

Next, the cartilage integrity should be assessed and, if joint endoprosthetics are performed, the proximal phalanx should be isolated. In some cases, its dorsal cortex may have a defect, which should be taken into account when resecting the head. Usually, resection of the base of the phalanges is not required. When forming canals, it is important to remember that the phalanx canal is formed first, since its medullary canal is smaller than the metacarpal canal. This is true for metacarpophalangeal joints II, III and V.

It is also necessary to cut off the ulnar portions of the dorsal interosseous muscles with the adjacent ligaments. In the metacarpophalangeal joint II, this can cause finger rotation, so if the correction of ulnar deviation can be performed without this procedure, cutting off these muscles should be avoided. Such manipulation is performed not only during joint endoprosthetics, but also during synovectomy, then (given the time reserve) it is possible to transfer these tendons to the radial side of the adjacent finger. Since the deformation is also caused by the ulnar displacement of the extensor tendons, their radialization is performed by any method available to the surgeon.

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Operating characteristics

To assess the effectiveness of joint endoprosthetics, both instrumental diagnostic methods (mainly radiography) and numerous scales and questionnaires are used. X-ray images can be used to assess the dynamics of the endoprosthesis stability, the correctness of the location of its elements, the degree of their migration, the appearance and severity of osteolysis. The intensity of pain is assessed both by the patient himself using a visual analogue scale and by the doctor when checking the functioning of the operated joint, the possibility of loading the operated limb, the need for additional support, when walking up the stairs and over long distances. Only by taking into account a set of factors can an objective assessment of the effectiveness of the operation be given.

After joint endoprosthetics in patients with rheumatological diseases, many researchers note good remote results: increased functional activity and decreased pain. It was shown that 10 years after joint endoprosthetics, most patients did not experience pain or the pain was insignificant. However, it is believed that pain in patients with rheumatic diseases is the most variable symptom, and the restoration of functional activity is significantly worse than in patients with other pathologies, which is due to the polyarticular nature of the lesion and the systemic nature of the rheumatological disease. In this situation, it is not always possible to objectively assess the functional state of one specific joint.

Factors Affecting the Effectiveness of Joint Replacement Surgery

The effectiveness of joint replacement is determined by many factors, such as:

• patient's somatic condition:
• disease activity and severity of systemic disorders;
• number of affected articular surfaces;
• stages of damage to the operated joint, the degree of its destruction and the severity of changes in the periarticular tissues;
• preoperative planning and selection of endoprosthesis;
• individually selected adequate rehabilitation program; qualification of medical personnel.

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Alternative methods

Alternative methods include arthroplasty, corrective osteotomy of the femur and tibia, arthrodesis. However, with the development of joint endoprosthetics and the improvement of endoprosthesis models, the indications for using the above methods are narrowing. For example, isolated corrective osteotomy, the purpose of which is to change the load axis and unload the affected part of the joint, in recent years has increasingly been performed by unicompartmental joint endoprosthetics, and arthrodesis is used very limitedly and according to strict indications.

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Contraindications to the procedure

Contraindications to joint endoprosthetics are determined taking into account the risk of intraoperative and postoperative complications, anesthetic risk. The patient's psychoemotional state is taken into account, as well as the feasibility of the operation in terms of further ability to lead an active life.

The following main contraindications to surgical treatment can be identified.

• Unsatisfactory somatic condition of the patient, identification of severe concomitant diseases that significantly increase the anesthetic risk and the risk of developing intraoperative or postoperative complications.
• Detection of foci of infection both at the site of the planned surgical intervention and at distant sites.
• Mental disorders that prevent the patient from adequately assessing his condition and following the postoperative regimen.
• Multiple soft tissue lesions that prevent the patient from using the operated limb or crutches for walking after surgery.

The last contraindication for joint endoprosthetics surgery is not considered absolute. In this case, it is possible to consider options for staged surgical treatment with preliminary restoration of the functions of other articular surfaces, which will allow the patient to regain the ability to stand and use additional support for walking.

Contraindications to endoprosthetics of the metacarpophalangeal joints, in addition to general ones (skin condition, patient’s psyche, etc.), include:

• dislocated articular surfaces with shortening of more than 1 cm or with severe loss of cortical bone;
• articular structures with fixed swan neck deformity and limited flexion at the proximal interphalangeal joint;
• destruction of the extensor tendons as a result of injury or underlying disease.

It should be noted that the contraindications listed above are considered relative (except for septic processes of the skin in the area of the operation), i.e. the operation is possible, but the effect and consequences are poorly predictable. Thus, with the development of fibrous ankylosis in the proximal interphalangeal joint, joint endoprosthetics can be performed, but the functions of the hand, naturally, will not be restored to the level that could be expected in patients with intact movements.

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Complications after the procedure

The most common complication after joint endoprosthetics is considered to be the development of instability of the endoprosthesis elements. Violation of bone tissue restoration in rheumatic disease associated with the development of secondary osteoporosis are unfavorable factors during joint endoprosthetics.

It is known that the development of osteoporosis and the risk of instability of the endoprosthesis in rheumatic disease are caused, on the one hand, by the influence of the underlying disease, the activity of the inflammatory process, reduced physical activity, the severity of functional disorders, and on the other hand, by the drugs used for treatment, which inhibit local growth factors and disrupt the adaptation of the bone to stress loads. In this regard, the risk of instability of the endoprosthesis elements in patients is increased. With the development of instability, clinically manifested by severe pain and impaired support ability of the limb, in most cases there is a need for revision arthroplasty.

Functionally, instability is associated with the mobility of the endoprosthesis under relatively small loads. During revision, the amplitude of displacement can range from several millimeters to several tens of millimeters. Radiologically, instability is detected by the appearance of a clearing zone between the implant (or cement) and the bone.

Data on instability development are highly variable. In one study, 6 years after hip arthroplasty, radiographic signs of acetabular component instability were detected in 26% of cases, and femoral instability in 8%. In another study, 8 years after cemented endoprosthetics, radiographic signs of instability were observed in 57% of patients. However, changes detected radiographically do not always have clinical manifestations. Thus, one study showed that in the period from 2 to 6 years after joint arthroplasty, none of the 30 patients operated on underwent revision surgeries, although small resorption zones were observed around 43% of femoral and 12.8% of acetabular components of the endoprostheses.

Other complications include:

• dislocation of the femoral component after total hip arthroplasty (according to various authors, the incidence of this complication is “about 8%);
• secondary infection (1-2% of cases);
• fractures of the femur and tibia proximal and distal to the components of endoprostheses (0.5% of cases):
• stiffness after knee replacement (1.3-6.3% of cases);
• damage to the extensor mechanism (1.0-2.5% of cases).

Complications after endoprosthetics of the metacarpophalangeal joints include, in addition to infections, implant fracture, development of silicone synovitis, loss of the initially achieved range of motion, and relapse of ulnar deviation.

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Care after the procedure

In the postoperative period, from the second day, patients should start moving: walking with crutches with a measured load on the operated limb, doing therapeutic exercise. It is necessary to start active and passive movements in the operated joint early, passive development of movements with the help of special devices. This is considered a guarantee of subsequent good functioning of the limb.

By the day of discharge (but removal of stitches), the range of motion in the knee should be at least 100, the patient should be able to fully care for himself, walk up the stairs. After hip arthroplasty in the postoperative period, there are temporary restrictions in movements (flexion, adduction, external rotation). These measures are necessary to prevent dislocation in the joint.

The rehabilitation period after endoprosthetics of the metacarpophalangeal joints is about 6 weeks and includes occupational therapy, classes with objects, physiotherapy, and wearing a dynamic splint.

References

Guidelines for Primary Knee Arthroplasty. Second edition, revised and supplemented, Kulyaba T.A., Kornilov N.N., Tikhilov R.M. St. Petersburg: R.R. Vreden National Medical Research Center of Traumatology and Orthopedics, 2022.

Hip replacement for coxarthrosis. Zagorodniy N.V., Kolesnik A.I., Kagramanov S.V. [et al.]. GEOTAR-Media, 2022.

Endoprosthetics for injuries, damages and diseases of the hip joint. Guide for doctors. Nikolenko V.K., Buryachenko B.P., Davydov D.V., Nikolenko M.V. Publishing House Medicine, 2009

Hip replacement. Fundamentals and practice. Zagorodniy N.V. Geotar-Media Publishing House, 2013