SURGICAL TREATMENT OF LOCALIZED INJURIES TO ARTICULAR SURFACE: THE CURRENT STATE OF THE ISSUE
Privolzhsky Federal Research Medical Centre,
Nizhny Novgorod, Russia
Restoration of localized defects of the hyaline cartilage of the articular surface is an actual problem of the modern medicine. Even small defects of the hyaline cartilage are considered by surgeons as serious injuries relating to further development of arthrosis and evident disorder of joint functioning [16, 2].
The Outerbridge classification (1964) is a common tool for estimation of injuries to the articular surface [41]. This classification estimates deepness and the square of destruction of the articular cartilage. Injuries of degrees I and II do not have clinical manifestations and do not require surgical treatment, whereas degrees of 3 and 4 are deep injuries which often result in fast development of arthrosis and require administration of the common methods of chondroplasty or nudge researchers to development of new techniques.
The objective of the review was estimation of the modern methods of surgical treatment of localized cartilage defects of the articular surface and efficiency of use in dependence on location, deepness, square of an injury, time of an injury, state of a cartilage of the adjacent articular surface and patient’s age.
The main techniques for chondroplasty of articular defects are classified according to the groups (the table).
| Table | ||||||
| The main techniques for chondroplasty of cartilage defects | ||||||
The most common techniques are described below.
The indication to osteoperforative techniques of chondroplasty are local destruction of the cartilaginous tissue expending to the subchondral bone (degree IV according to Outerbridge, 1961) over the area not more than 2 cm2 in patients younger 60 [44]. These techniques are based on the concept of violation of bone integrity with the aim of approaching from deep layers of the spongy bone to the surface of the defect [18].
Abrasive chondroplasty was offered and substantiated by P.B. Magnuson in 1941. In 1979 R.P. Ficat described the arthroscopic technique [28] consisting in extensive removal of the exposed cortical bone to the spongious bone tissue to the depth of 1-3 mm up to exposure of intraosseous vessels and appearance of hemorrhagic exudate. The borders of the defect within the limits of a healthy cartilage were prepared transversely to the subjacent bone resulting in appearance of dish-shaped defect with ideal conditions for retention of the blood, and bone marrow in the region of the injury. The disadvantage of the technique is development of hemarthrosis in early postsurgical period after appearance of extensive bleeding surface in the region of the bottom of the defect [7].
In 1959 K.H. Pridie offered a technique of tunneling [43]. The technique is based on drilling the base of the cartilage defect with the drill of 6 mm diameter and the same intervals between the holes. At the present time, deep multiple drilling of the defect base is made with K-wire or 1.5-3.5 mm drill. However some authors indicate thermal injuries to the subchondral plate during drilling with negative influence on treatment results [27].
There are several modifications of the technique, when subchondral pin tunneling for the femoral bone is conducted in retrograde manner or from unloaded regions of the articular surfaces in the intercondylar pit in parallel with identified regions of chondromalacia [3, 4].
In 1994 J.R. Steadmann [44] described microfracture as a method for treating localized cartilaginous defects of the articular surface. He offered a special awl-perforator for creation of subchondral bone microfractures in the cartilage defect. The negative effect of heating and burn of the bone plate was absent during drilling. At average, 3-4 holes about 4 mm deepness are created per 1 cm2. Arthroscopic awl-perforators have the marks of deepness and different angles of inclination of the operating part: 0°, 30° or 60° from the longitudinal axis. It allows osteoperforation in hard-to-reach areas of the joint [44]. The negative moment is thickening of the subchondral bone plate after creation of microfractures resulting in significant worsening of trophism of the formed regenerate [31].
Summarizing the results of the analysis of the osteoperforative techniques of chondrogenesis stimulation, it is necessary to note that such techniques are often used as a part of treatment algorithm for local cartilage defects and are the options for primary surgical intervention [25]. Wide spreading of the above-mentioned techniques is favored by simplicity of realization and minimal set of necessary surgical tools [48]. The disadvantages of the techniques are weak fixation of blood elements, bone marrow and growth factors in the region of the defect on the surface of the subchondral bone, as well as insecurity during axial load and during motions in the joint [45].
As result of usage of the osteoperforative techniques, the cartilaginous regenerate appears in the defect region. The regenerate is similar with the fibrous cartilage, which has significantly worse biomechanical characteristics in comparison with the hyaline cartilage. The efforts of restoration of cartilage defects with use of such methods show good results in 75 % of patients within the last 5 years [48]. Many authors indicate worsening treatment outcomes over time [6, 33].
For more organ-specific replacement of isolated defects of the articular surface the group of the methods was offered. The methods are based on transplantation of the intact articular cartilage with subjacent bone blocks. One of the most wide-spread techniques is osteochondral autografting (mosaic chondroplasty). The results of clinical approbation of osteochondral autografting were described by H. Wagner in 1964 [10]. Then the technique was modified, and the arthroscopic tools for its realization were developed [32].
The concept of osteochondral autografting consists in preservation of vitality of chondrocytes of the intact cartilage, which is grafted with subjacent bone tissue. This technique supposes transplantation of the bone-cartilage graft from unloaded departments of the joint into the region of the articular cartilage defect. At that, the donor regions are the anterior lateral regions of the femoral condyle and its intercondylar space [21]. The operation may be realized with only arthroscopic techniques or by means of miniapproaches. The patient’s age is not over 45. The outcome of surgery is filling out the defect with the hyaline cartilage with regions of fibrous cartilaginous tissue along the borders of the cylinders. There is a disputable question about the size and the amount of grafted cylinders. However most authors agree that osteochondral autografting gives the highest efficiency during transplantation of the blocks of 7 mm in diameter with the amount of 3-4 pieces [9]. Therefore, mosaic chondroplasty gives the highest efficiency for young patients with limited defects of the articular surface of 4-6 cm2. According to the various authors, the mid-term good and excellent outcomes were noted in more than 80 % of the cases [2]. Despite of attractiveness of the method, its usage is limited by the small square of donor regions of the joint and additional injuries to tissues of the articular surface during collecting the graft [1].
The problem of limitation and painfulness of donor regions could be solved by replacement of articular surface defects by means of transplantation of orthotopic bone and cartilage allografts of identical sizes [40]. But because of bad outcomes of integration of a bigger graft and the possibility of hepatitis C and B or HIV, the technique did not acquire wide spreading [17, 34].
Limited choice of chondroplasty techniques for extensive defects of the articular surface favored development of the methods on the basis of cellular materials.
The needed researches were initiated in 60s of the last century. However the first data about treatment of posttraumatic defects of the articular surface by means of chondrocyte autografting were published only in 1994. M. Brittberg conducted transplantation of autologous chondrocytes under the periost flap, which was sutured along the borders of the prepared defect of the articular surface [23]. The first stage of diagnostic arthroscopy was realized by means of grafting of the fragment of the intact articular cartilage from the unloaded region, with its following laboratory cultivation during 3 weeks [23].
The indication for chondrocyte autografting is presence of full-thickness cartilage defect of loaded surface over the area from 3-4 to 16 cm2 in young patients [22]. After the first publications the technique has become the real breakthrough in treatment of extensive cartilaginous defects. However presence of complications caused by periosteal hypertrophy and implantation of the periosteum as the tectorial membrane (25-42 % of the cases according to the data from the various authors) resulted in necessity of revision interventions [39].
Later the problem was solved by development and implementation of biocompatible tectorial membranes, which realized mechanical protection of the regenerate during axial and tangential loads, and favored maintenance of the phenotype of the implanted cells [11, 13]. According to some authors, chondrocytes, which are cultivated in the monolayer, lose their phenotype after placement into the region of the defect, as well as lose the ability to produce intercellular matrix and collagen of type 2. Three-dimensional structure of the carrier matrices favors maintenance of the phenotype of the cells [27, 36]. At the present time, the common matrices are based on the collagen, hyaluronic and polyglycolic acids, agarose, alginate, various polymers (PLA, PLLA, PGA, PLDLA) in view of fibers, network or gel [12, 33]. The main criteria of the materials are biocompatibility and resorption within the needed time and without appearance of toxic molecules [19]. Solid carriers favor cellular adhesion and create three-dimensional structure of the regenerate, whereas gels significantly limit metabolism of implanted cellular culture [35].
Originally, the tectorial membranes (used instead of periosteal flap) were used in combination with osteoperforative techniques of chondroplasty [15]. They retained the regenerate in the region of the formed bed, carried the function of mechanical protection that favored more complete replacing the defect by fibrous-cartilaginous tissue – so called autologous matrix-induced chondrogenesis (AMIC) [29, 30, 36, 42].
Carrier matrices became more wide spread in combination with chondrocyte autografting. In 1998 P. Behrens et al. conducted the first transplantation of autologic chondrocytes cultivated on the dual-layer matrix composed of pig collagen of types 1 and 3 [19]. The technique supposed two-stage surgical intervention. The first stage included harvesting of necessary volume of the cartilage and unloaded region of the joint with following traditional monolayer cultivation of chondrocytes during 3-4 weeks until 15-20 million of the cells were achieved. The matrix was inoculated with chondrocytes and was cultivated in autoserum during 3 days. As result, three-dimensional regenerate was developed with smooth distribution of the cells over the whole square of the carrier, which was implanted into the region of the prepared defect during the second stage [33, 37]. According to the authors’ reports, the good outcomes were found in 75 % of the patients during 10 years of the follow-up [24, 48]. However, some authors indicate the comparability between long term results of treatment, the techniques of chondrocyte autografting and osteoperforation during similar conditions [14].
Low regeneration capability of chondrocytes cultivated in monolayer or on the matrix resulted in development of the new cultivation method – three-dimensional aggregation of autologous chondrocytes with formation of chondrospheres, when cellular aggregation happens in the solution without physical or chemical stimulation [47]. As result of two week cultivation of chondrocytes, the spheres of 500-800 µm appear, and the number of the cells is two times higher than the cellular amount for the same volume of native cartilaginous matrix. During moving to the injury region, the chondrocytes adhere to the borders of the defect and merge together on the surface of the chondrosheres. It allows refusal from additional measures for fixation of the regenerate. The disadvantages of the implantation technique of chondrospheres are high costs of chondrocyte cultivation, need for two-stage intervention, additional injuries to healthy cartilage tissues during collecting the cultivation materials [48].
Many authors note the event of differentiation of chondrocytes after implantation from favorable conditions of cultivating medium to the region of the prepared defect, where aggressive conditions for life of the cells appear within next several days. Because of development of aseptic inflammation many implanted cells die, other cells lose their phenotype [26]. Moreover, the proliferation potential of the chondrocytes decreases with age that significantly limits usage of the techniques of chondrocyte implantation in patients of older age groups [38].
The scientists started using of precursor cells from other tissues in their attempts to increase the regeneration potential of implanted cells. Fat tissue and synovial membrane are used for such aims in most cases. Directed chondroblast differentiation of such cells is possible during development of optimal conditions of cultivating medium. However after placement of cellular culture into the region of the cartilaginous defect, the forcedly cultivated cells quickly lose their phenotype and the ability to produce collagen of type 2 and hyaline-specific markers [5].
Bone marrow stroma cells (BMSC) present a perspective direction for restoration of localized defects of the articular cartilage. Owing to the properties of plural potency under influence of microenvironment of the region of the cartilage defect, BMSC are able to differentiate towards chondrocytes [29]. The value of the technique is strengthened by the possibility of use of allogenic stromal cells of bone marrow. Considering relatively low costs of cultivation, it allows single-stage replacement of the articular surface defect by means of the cellular graft [46]. The techniques of puncture introduction of BMSC after preliminary tunneling of the base of the defect are described. However the negative moment is development of dense scars in the region of administration, irregular distribution of the cells over the articular surface and development of adhesions and joint stiffness [48]. For provision of required concentration of the cells in the region of the defect the method of chondroplasty with use of nanoferretic-labeled BMSC and a directional magnetic field are used [48]. There are some publications of the chondroplasty techniques on the basis of BMSC as part of various carrier gels. However many researchers think that such conditions result in loss of the ability of receptor and chemical interaction with each other and with periphery and the base of the defect. Also trophism of the regenerate is disarranged because of the physical properties of the gel [26]. The best results of treatment are related to BMSC in combination with the tectorial membrane. There are some methods of puncture introduction of cellular suspension with use of the soft catheter into the region of the prepared defect covered with the membrane, but such introduction does not result in uniformity of distribution of cellular culture in the region of the defect [8, 9].
The next stage is BMSC implanting after preliminary cultivation on different solid carriers. The tectorial membranes are commonly used as matrices [46]. BMSC cultivation may be realized without additional injuries to the joint in contrast to autochondrocyte cultivation. Bone marrow stromal cells are characterized by higher regeneration and proliferation potential in comparison with chondrocytes. It holds out a hope of good long term results of treatment of local injuries to the articular cartilage which are restored with such techniques.
Despite of the wide range of techniques for repair of localized defects of the articular cartilage (from the techniques of osteoperforation to tissue bioengineering) none of them results in complete organ-specific restoration of cartilaginous hyaline tissue. The surgeons approach to salvation of the problem after development of each new method.