Modern aspects of the treatment of Koenig’s disease in children

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Epidemiology and pathogenesis.

Osteochondrosis of the knee joint is a common cause of pain and functional disorders of the knee joint in children and young adults. This is a pathological condition in which the subchondral bone becomes Hypo-and then avascular,which leads to the destabilization of the chondral coating. With the progression of the disease, the cartilage, and more often the bone-cartilage complex in a limited area can completely separate from its bed under the influence of shock and shear forces [8]. This inevitably leads to an anatomical violation of the integrity of the hyaline cartilage of the joint, the formation of free intra-articular bodies, a significant loss of the sliding effect, and the appearance of blocks. [3].

Ambroise Pare described observed "intra-articular mice" in 1558. Koenig was the first author to use the term dissecting osteochondrosis in 1887 and pointed to the role of trauma as a predisposing factor. He also described this process as inflammatory, but in 1926 revised his statement . At the same time, Paget considered the formation of intra-articular free bodies to be a consequence of avascular necrosis. [3]

According to modern ideas of many specialists, dissecting osteochondrosis is a pathological process that affects the subchondral bone of the knee joint. In children and adolescents with open growth plates, it is (juvenile), and in young people with closed growth plates, traditionally dissecting osteochondrosis of adults. The development of the disease at the age of 14 years is considered as a juvenile form of Koenig's disease [8]. In the absence of timely diagnosis and proper treatment, there is a high probability of developing severe degenerative joint changes at a young age [7].

The causes that contribute to the occurrence of the disease include: local ischemic necrosis of the subchondral bone, as a consequence of repeated microtraumas, violation of the process of enchondral ossification, hereditary predisposition and endocrine disorders [5].

Since Koenig's inflammatory theory, numerous hypotheses have been put forward regarding the true pathophysiology underlying the formation and progression of knee joint lesions, but no theory has received a consensus. The histological picture often describes necrosis of the subchondral bone, and it remains unclear whether the presence of necrosis is primary or secondary in the chain of pathogenetic changes [3, 4, 5, 6, 20].

There is a theory of chronic macrotraumatization its proponents claim that the initial stress reaction occurs in the subchondral region of one of the condyles of the hip, and with further loading leads to the formation of a "stress" subchondral fracture. Repeated loading prevents the healing of an impression fracture, and leads to local aseptic osteonecrosis [2]. The free osteochondral fragment is further delaminated and separated from the fracture bed, which leads to unstable deep damage to the hyaline cartilage [28].

In terms of aggregate data of many authors in 69% of cases the lesion is localized in the lateral zone of the medial condyle of the femur, 6% - in the extended, so-called "classic" zone with the capture of the portion of the bottom load surface of the femur, it accounts for 10% in the lower Central load area and 13% in the lower Central loading zone of the lateral condyle of the femur . In 2% of cases, necrotic foci are located in the anterior part of the lateral condyle of the femur [18].

Taking into account the opinions of various authors, the most likely is the polyethological theory of the development of dissecting osteochondrosis in children, it includes chronic microtraumatization, endocrine imbalance, violation of ossification processes in the distal epiphysis of the femur, microcirculation disorders with angiospasm, infectious thrombosis and other causes. [3, 5, 12, 13, 14].

Classification.

Dissecting osteochondrosis of the knee joint is conditionally divided into two forms: juvenile and adult. Juvenile osteochondrosis is characterized by a debut at the age of 10-15 years against the background of unclosed growth zones. Prognostically, this form is considered the most favorable. The adult form can develop into an older one as a rule, usually up to 50 years old. [9]

To assess the extent of damage to the femoral condyle, Milgram J. W. presented a classification of the disease in 1978. In accordance with this classification based on the review radiographs the author identified four stages of the disease:

1. Characterized by the presence of linear transparency in the subchondral bone in the epiphysis zone
2. There is a focus of sclerosis of the subchondral bone with an x-ray transparent zone separating the local lesion from the base of the defect
3. There is a fragmented or collabated zone of dense calcified hyaline cartilage, sometimes involving subchondral bone in the defect cavity
4. Sclerotic bones with an undefined x-ray transparent zone, reactive lines at the base of the defect in the femoral condyle, and the presence of a free intra-articular body are visualized.

Today, the classification proposed by the International society for cartilage restoration (year) . In this classification, dissecting osteochondrosis is also divided into four groups by morphological feature|.

At the first stage, softening of the cartilage is detected without breaking the integrity.

The second stage is marked by the presence of a stable section of cartilage separation;

In the third stage, a violation of the continuity of the hyaline cover is diagnosed due to the death of cartilage at the site of the pathology without its dislocation

The fourth stage closes the chain of pathological processes and involves a violation of the continuity of the cartilage with the presence of a free fragment, which can be located both within the formed defect and beyond [35].

To divide the dissecting osteochondrosis into groups of the above classification , the criteria obtained as a result of radiation, MRI, ultrasound diagnostics, as well as intraoperative picture of the joint are used

Clinic.

In the initial stages, the disease is latent and is often detected as an accidental x-ray finding during an examination due to a different pathology. The main clinical signs are non-specific: pain, joint discomfort, and edema after exercise [1].

Typical are complaints of pain with axial load on the limb in the position of light flexion in the knee joint, which are amplified when performing rotational movements of the lower leg with a fixed foot. There may be other common clinical manifestations: lameness, smoothness of the contours of the joint, blockages . Active and passive movements in the joint in the absence of free intra-articular bodies are not limited. There may be a pain syndrome in the position of extreme flexion, which is caused by pressure in the projection of the articular surface of the affected condyle [2].

Dissecting osteochondrosis in adults and children differs significantly in the course and prognosis. Given this circumstance, we can assume that we are talking about two different diseases [7]. At the first stage, subchondral necrosis of the spongy bone and bone marrow occurs, but the articular hyaline cartilage still retains its viability. At the end of this stage, there is a weak limited compaction of the bone substance in the necrosis zone [38].

The second stage occurs a few months later (usually 3-4 months) from the onset of the disease. There is a deformation of the bone beams at the border with healthy bone, the trabecular structure of the bone is broken, the structure of the epiphysis is compacted and reduced in height. The articular surface is deformed. The duration of this stage is 3-5 months.

The third stage is characterized by slow resorption of necrotic bone against the background of revascularization. The proliferation of fibrous-cartilage tissue in the form of protrusions leads to fragmentation of the necrotised area of the bone. The duration of this stage is 1-3 years.

The fourth stage is characterized by the replacement of bone fragments, as well as connective tissue and cartilage strands with newly formed spongy bone substance with a rough structure (sometimes with the development of cysts). The duration of the stage varies from 6 months to 2 years. [40].

The clinical picture of dissecting osteochondrosis is characterized by the absence of reliable pathognomonic manifestations, which to a certain extent makes it difficult to make a correct diagnosis in a timely manner [2]. Most often, Koenig's disease occurs in children who are engaged in active sports, but it can also occur in patients who lead a quiet lifestyle.

Late diagnosis of the disease, when there is the development of arthralgic complications (synovitis, pain syndromes, contractures), leads to the prolongation of the pathological process to youth and older age. This, in turn, causes the development of gonarthrosis with a subsequent pronounced decrease in joint function and restriction of the patient's ability to work [2].

The increase in the number of children with Koenig's disease in advanced stages requires doctors to pay more attention to long-term pain syndromes, recurrent synoviitis, blocks and pain contractures of the knee joint. It is necessary to conduct a thorough differential diagnosis of Koenig's disease with meniscal pathology, rheumatoid arthritis, and a number of other specific pathological processes. [3]

Treatment.

The treatment strategy for dissecting osteochondrosis depends on the stage of the disease and the severity of the clinical picture. There are surgical and conservative treatment. In the recent past, the main method of treatment of dissecting osteochondrosis of the knee joint was arthrotomy with the removal of free intra-articular bodies. Most often, arthrotomy was performed in the final stages of the disease, when there was a bone defect in the area of the femoral condyle. Treatment directly depends on both the patient's age and the stage of the pathological process [38].

Many authors prefer conservative treatment in the treatment of juvenile dissecting osteochondrosis in young patients with unclosed growth zones and open epiphyses[5, 6].

Conservative treatment is effective at an early stage of the disease, when there are no pronounced radiological changes in the bone, and only edema of the bone substance is detected on MRI. At the stage of reduced magnetic resonance signal from the affected area of the bone, conservative treatment is also possible, but the risk of irreversible changes in microcirculation is higher, and therefore, the probability of adverse outcomes increases. [13, 14].

Most children suffering from juvenile osteochondritis can be successfully treated conservatively [6, 19]. Active physical activity is not recommended for a child. Perform immobilization of the limb by means of unloading orthosis for a period of 6-12 weeks. A course of physiotherapy is prescribed.

If the patient regresses pain, there is a positive radiological dynamics. then after 12 weeks, it is allowed to start sparing loads on the diseased limb, excluding active sports and forced physical activity . [7].

Currently, popular tools are chondroprotectors and synovial fluid prostheses [14].

Conservative treatment for stage 1-2 of Koenig's disease is aimed at optimizing regeneration processes, for which until recently electromagnetic stimulation was used in combination with joint unloading [11]. The duration of conservative therapy in this case is from 10 to 18 months. During this period, sports activities are completely excluded and a strict protective regime is recommended. For a period of up to two months, unloading of the joint is prescribed, the patient must walk on crutches, without stepping on the sick leg. When reducing the pain syndrome, the complex of conservative therapy includes a course of physical therapy that includes non-strength isometric exercises [21].

It is advisable to conduct repeated courses of treatment. In a recently published retrospective study of 42 patients with juvenile dissecting knee osteochondritis (66%), patients with stable injuries were able to recover after conservative treatment and persistent remission [13, 14].

The nature of the course of the disease and the effectiveness of conservative treatment are influenced by factors such as the size of the pathological focus, age and gender. Localization of the process on the condyle remains controversial [5, 6].

In modern special literature devoted to conservative treatment, the main principles of achieving a positive result are formulated. This is an orthopedic regime with a reduction in sports loads and the creation of rest for the affected segment, a comprehensive medical treatment aimed at activating recovery, including local injection therapy, and regenerative medicine resources. Physiotherapy procedures to reduce pain, improve trophic function, and activate repair. [12, 14].

Surgical treatment is indicated in cases where conservative measures are ineffective, as well as in unstable lesions, especially in adults [14].

A number of authors recommend surgical treatment in children with dissecting osteochondrosis only when the disease progresses, limiting the removal of free bodies [36, 37, 40].

According to most authors, the results of surgical treatment of Koenig's disease are better in young patients in the age group from 6 to 12 years, which is due to the large reparative potential. Unsatisfactory anatomical and functional outcomes correlate with atypical sites of cartilage damage, multiple lesions, and the presence of concomitant diseases [37].

Surgical options include simple removal of a fragment or free intra-articular body, reparative osteoperforation of the subchondral bone, fragment refixation, microfracturation with osteochondral autografts and various cellular technologies. [11, 16, 17].

The technical capabilities of minimally invasive arthroscopic surgery are increasing every year [10, 11, 12].

The goal of surgical treatment is to restore the articular surface of the knee joint in the shortest possible time. it is advisable to resort to osteoinductive methods, in cases of vitalized lesions, in cases of osteonecrosis, or reconstructive with the removal of fragments or free bodies [24, 25, 26].

In cases where signs of instability of the knee joint are detected, surgical treatment is indicated regardless of the patient's age. Areas of articular cartilage are considered to be vitalized, with the preservation of the subchondral layer and complete congruence of the articular surfaces [25].

Non-viable cartilage injuries include those that cannot be preserved and stabilized, since they are present as free intra-articular bodies or are fragmented, violate the congruence of articular surfaces, and also determine the pathology of the subchondral bone [17].

Recently , the most common surgical method of treating patients with this pathology is arthroscopic, in which the size of the hyaline cartilage defect is determined and, if necessary, the possible refixation of the separated fragment is performed. Fixation is recommended in cases of fresh injuries (up to 3 weeks) and the presence of a large, suitable for this purpose ,osteo-chondral fragment. In other situations, it is advisable erase, abrasive chondroplasty curette with the formation of stable edges of the cartilage defect of microproteinuria defect, the need to count on inducing the formation of fibrous cartilage [1].

A commonly used technique today is arthroscopic refixation of a detached bone-cartilage block. Bruns J points out a number of technical difficulties and recommended fixing only large detached fragments [32].

Totch F. and Tisci MJ. found that the defect in the region of the condyle was filled with fabric, named them vibrogram. Repeated traumatization of this zone or a slight load led to degeneration of the cartilage surface [27].

Crawforrd D. Safran MR used a Kirschner spoke as a fixing material [ 38]

Hughes JA et al. at the same time, it is believed that open arthrotomy and internal fixation of free bone-cartilage blocks of significant size using Kirschner spokes is much more effective than removing fragments and curetting the bottom of the niche [ 33].

However, a number of authors still did not recommend using this technique due to frequent migration of spokes and free fragment, noting a very low survival rate [27, 38].

Krappel F. A, et al. published data on the technique of defect plasty in patients with dissecting osteochondritis using allogeneic and autogenous osteochondral grafts. The method consists in closing the niche with grafts from other areas of the articular surfaces [34].

Nakamae A and co. it was suggested to fix grafts or a detached fragment using AO/ASIF screws [40]. Osteosynthesis with screws provides interfragmental compression and mechanical strength, which creates favorable conditions for the flow of biological regeneration processes. Removal of metal structures is recommended no earlier than 8 weeks [36].

Biodegradable implants are promising. since there is no need to repeat the operation to remove the structure. Some authors Express doubts about the need for interfragmental compression using such screws, given their rapid enzymatic degradation [30], reactive synovitis accompanying implanted structures complicates the recovery process of patients [32].

The results of reconstructive operations using biodegradable implants, cannulated screws and screws with partial threads do not show statistical differences. [29].

According to a number of authors, fragmented areas of cartilage, regardless of size, are subject to simultaneous removal, because they are considered unstable, because they consist of coarse-fiber connective tissue, lack vascularization and can cause instability of the knee joint. [31, 32, 34]

Simple in execution and popular treatment method today is microfracturation, as a way to stimulate regenerative processes of the bone marrow [38, 40]. The technique consists in creating micro-fractures after curettage at the site of the affected area of the subchondral bone.

Microfracturing is performed with a special arthroscopic chisel, applying notches to a depth of 2-4 mm with a distance between them of about 4 mm [5]. As a result, a so-called superglue is formed in the injury zone, which is the optimal environment for stem cells migrating from the bone marrow, ensuring the formation and replacement of the joint surface defect with fibrous cartilage [11].

Microfracturation is indicated in cases of osteonecrosis foci less than 4 cm2 in size. According to the method, artificially created micro-fractures allowed to obtain satisfactory results with a follow-up period of 11 years [32] However, a systematic analysis of 28 studies involving 3122 patients showed inconclusive results of observations after 2 years [28].

One of the minimally invasive methods of surgical treatment of dissecting osteochondrosis is revasularizing osteoperforation. This method, which causes osteoinduction, showed satisfactory results in 72% of cases, especially with lesions less than 2 cm2 [39] .

Revascularizing osteoperforation is most often performed under arthroscopic control, less often by miniarthrotomy. Open fixation is performed in cases of unstable lesions with a sufficiently large subchondral component. [2, 36]. To perform the technique, a Kirschner spoke or a thin awl is used. Perforation channels are directed perpendicular to the articular surface and penetrate deep to 2-4 cm in the thickness of the condyle 5-6 mm of intact bone is considered the optimal distance between the perforated holes [5, 9].

However, the results of this technique showed that in the late stages, in the presence of flotation of the bone-cartilage fragment, its effectiveness does not exceed 50%, and in cases of sequestration, the effectiveness of revascularizing osteoperforation remains extremely doubtful. [7, 12, 13]

Promising experimental and clinical results were shown by the combined treatment method, which includes microfracturing, filling the defect with crushed autochrystal and covering it with a collagen membrane suspended in the platelet-rich autoplasm [2].

Mosaic autoosteochondroplasty is used for large lesions with a violation of the integrity of the subchondral bone, for which microfracturation is not sufficient [10, 11].

There are a large number of articles in the literature on the application of this technique. [23, 24, 27]. It includes the collection of osteochondral grafts in the form of cylinders from non-loaded zones and their implantation in the area of the lesion with the help of special tools. The number of transplanted osteochondral areas depends on the area of the affected area . Good results of this method were obtained in 79-94%, and radiographically confirmed integration of the graft with a follow-up period of 18 months [24, 26]. However, according to other authors, an important disadvantage of the method is the non-curable pain syndrome in the area of the donor bed [16, 17].

Autotransplantation of chondrocytes is indicated for single osteochondral lesions larger than 10 cm2[9, 11] . The method is carried out in two stages. At the beginning of arthrocopy, the chondromalacia focus is sanitized and the biomaterial is collected. Chondrites are cultured in vitro for three to four weeks, under special conditions . Then, by repeated arthroscopy, the resulting mass of cultured chondrocytes is implanted into the focus after preparing the bed. The operation is completed by the Last sealing of the defect filled with new chondrocytes using a membrane . which, among other things, is an additional means of fixing [24].

Clinical results of follow-up from two to ten years showed satisfactory results in 71-91% of cases[34], especially in children and adolescents with osteonecrosis foci less than 6 cm2 in size. In larger foci, chondrite implantation may be combined with elements of bone autoplasty after osteoperforation or intra-focal resection [38].

The result of microproteinuria, autoandrophilia and autoindentation chondrites restitution cartilage cover was different. Many authors have recognized that microfracturing leads to the formation of hyaline cartilage (type II collagen), which grows in the spaces between the osteochondral cylinders of mosaic plastic. [33].

A method of combined transplantation of auto - and allogeneic bone-cartilage grafts is known [1, 7, 15].

In 1990, there was a report of an attempt to transplant the rib autochondria. Cartilage defects of the 3rd-4th degree were closed with a perichondral graft, which was fixed with a fibrin glue [7, 32].

After 1 year, arthroscopic examination revealed that the cartilage defect was filled up to 90%, but after 8 years, it was found that 20% of cases were accompanied by enchondral ossification of the transplanted cartilage [16].

LaPrade and co-authors analyzed the results of biopsies of patients who underwent autotransplantation of chondrocytes observed the appearance of fibrous cartilage without signs of integration with surrounding tissues, and considered that the term "hyaline-like" is incorrect [31]

Homming used perichondral transplantation for hyaline cartilage defects of the knee joint of various origins [31]

Even earlier, the defects were filled with a periosteum, which is placed with its cambial layer on the surface of the bone defect after its debridement. In a repeated study, most of these patients did not show signs of chondroregeneration at the site of plastic surgery during arthroscopy [6, 32].

The results were generally satisfactory, taking into account the medium-term duration of observations [27, 29, 30]. The disadvantages of this method are the cost, availability and viability of the graft, as well as the likelihood of immunological reactions. [15].

Cell culture technologies are actively developing all over the world. In 1994, scientists from Sweden published the results of the use of autotransplantation of cultured chondrocytes (ACI) in the treatment of hyaline cartilage defects in the knee joint [32]. The method includes two step operations: 1. collection of 200-300 mg of cartilage from the unloaded joint surface, chondrocyte culture for 4-6 weeks, 2. introduction of chondrocytes under the closed periosteal flap defect [33, 12]. The disadvantages include a high risk of developing periosteal hypertrophy and arthrofibrosis of the joint, which require revision and joint mobilization interventions [33].

Subsequently, various inert collagen membranes were used to close the transplanted chondrocytes [3, 34]. In 2012, the third generation of ACI techniques based on the use of biological matrices was proposed. [12]

Another type of cell technology development is matrix-induced autogenous chondrogenesis, which is performed using a matrix consisting of pig collagen types I and III. The matrix can be fixed with either sutures or fibrin glue. The advantages of this method include a single-stage operation without preliminary cartilage sampling and economic feasibility, due to the lack of need for chondrocyte cultivation [39].

According to some data, mesenchymal stem cells are a good alternative to ACI and AMIC, showing good long-term results. [43, 39].

Having studied the opinion of many authors, we believe that the key to successful replacement of a cartilage defect is the production of collagen using the culture of its own chondrocytes. When tissue is taken from the donor site, chondrocytes produce type II collagen. During their cultivation, their properties change. If chondrocytes form a monolayer culture, they begin to produce type I collagen. After placing this culture in the defect on the articular surface, type II collagen is produced again [19]. After implantation, chondrocytes are located on the border with a healthy layer of cartilage and later fully integrate with it

In our opinion, the surgical tasks are to restore the congruence of articular surfaces by improving the vascularization of the affected area, rigid fixation of an unstable fragment, and protection of the supporting part of the loaded condyle in the postoperative period. Due to the rarity of this pathology and the lack of research with a high level of evidence, further development of treatment methods is necessary.

About the authors

Alexander A. Vorotnikov

Stavropol State Medical University, Federal State Budgetary Educational Institution of the Ministry of health of the Russian Federation

Email: vorotnikov@mai.ru

MD, PhD, Professor, Head of the Department of traumatology and orthopedics with a course of CPE

Russian Federation, Stavropol

George A. Airapetov

Stavropol State Medical University, Federal State Budgetary Educational Institution of the Ministry of health of the Russian Federation

Email: airapetovga@yandex.ru

MD, PhD, associate Professor of the Department of traumatology and orthopedics with a course of CPE

Russian Federation, Stavropol

Vacheslav A. Vasyukov

Stavropol State Medical University, Federal State Budgetary Educational Institution of the Ministry of health of the Russian Federation

Author for correspondence.
Email: argus-1971@mail.ru
ORCID iD: 0000-0001-9862-1726

assistant of the Department of traumatology and orthopedics with a course of CPE

Russian Federation, Stavropol

Vladimir G. Yagubov

Stavropol State Medical University, Federal State Budgetary Educational Institution of the Ministry of health of the Russian Federation

Email: Wvova26@yandex.ru

assistant of the Department of traumatology and orthopedics with a course of CPE

Russian Federation, Stavropol

References

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