Bio-Orthopedics: A New Approach to Osteoarthritis and Joint Disorders

Abstract

Osteoarthritis is a major cause of functional limitation and a raising burden in aging population. Lately more research is directed into finding biological enhancement of healing processes in joint dysfunctions. Biological cell-based therapies for cartilage restoration treatment were created to address the need for the long-term viability of repaired tissues. Additionally, the use of biologic therapies is also considered in common disorders affecting ligaments and cartilage. However, if inevitable arthritic changes commence biological therapies offer options to delay the need for arthroplasty. This chapter provides insights into these regenerative, joint preservation techniques for cartilage treatment, osteoarthritis, and other joint disorders.

1. Introduction

Osteoarthritis (OA) is one of the most common joint diseases; characterized mainly by joint pain and functional impairment, due to cartilage degeneration, subchondral bone remodeling, and synovial inflammation [1]. OA affects 7% of the global population [2], making it an important problem to solve for the orthopedic surgeons.

Tissue healing is limited not only by the biochemical environment but also by other coexisting factors such as diabetes, smoking, hypercholesterolemia or local factors, which can further weaken healing [3]. Biological response has been studied for many years in order to optimize the healing processes. These have resulted in cell-based, cytokine-based, and scaffold-based therapies [4]. In this chapter, we analyze current concepts in the use of biological treatments. This book chapter intends to provide a review of the current status of biological therapies for OA and other joint disorders in orthopedics.

2. Biological options

2.1 PRP

Lately, research in OA has moved the attention toward biochemical pathways that can be aimed therapeutically through biological intervention. In the past decade, a great interest has been focused on platelet-rich plasma (PRP). It is one of the “hot topics” of regenerative medicine due to its potential to help in different conditions. PRP has surfaced as a biological therapy for the treatment of cartilage injuries and for intra-articular application to address knee pain. PRP contains cytokines, growth factors, and inflammatory mediators, all capable of stimulating cartilage, subchondral bone, and soft tissue healing [5]. PRP contains a significant number of growth factors and proteins in the alpha granules of platelets, that were observed to have regenerative and analgesic effect [6, 7]. What is more, studies demonstrated that platelet-rich plasma (PRP) has an anti-inflammatory influence and counteracts catabolic processes within the joint [8, 9, 10]. Additionally, it has been shown to promote chondrocyte proliferation and increase the synthesis of collagen and proteoglycans and for this reason, the application of PRP for osteochondral pathologies has increased [5, 11]. PRP can be categorized as leucocyte-rich PRP (L-PRP), leucocyte-poor PRP (LP-PRP), or platelet-poor plasma (PPP) depending on the preparation technique. The ingredients of PRP categories vary, depending on which system is used to prepare the autologous blood, so care must be taken when choosing the method. There is no one gold standard, so injections of PRP can be done once or in cycles of 3 or more injections. PRP is acquired from patients’ peripheral blood. The venous blood is centrifuged in a special probe, according to instructions provided by the manufacturer. When using intra-articularly the PRP is injected into the joint after careful skin disinfection at the needle entry point. The highest beneficial effect is seen at 6 months after cycle of injections, however it may last up to two years [12]. Authors of a meta-analysis of randomized controlled trials using PRP in treatment of knee OA concluded that a statistically significant beneficial effect over placebo was observed at 6 and 12 months [13]. It was also shown that PRP is more effective both in short- or long-term pain and functional recovery when compared to HA [14].

2.2 Hyaluronic acid

HA is a non-sulphated glycosaminoglycan that consists of D-glucuronic acid and N-acetylglucosamine units. It ensures tissue hydration due to its hydrophilic properties and high solubility in an aqueous environment [15]. In a healthy joint it is produced by the synovium, exactly the type B synoviocytes and fibroblast. Its role is to preserve the viscoelastic and functional characteristics of the articular cartilage [16] in the same time promoting chondrocytes proliferation and differentiation [17]. Additionally, it provides joint lubrication and shock absorption. Interestingly in a study HA was shown to inhibit tissue nociceptors [16]. HA also inhibits IL-1β-induced oxidative stress and the inflammatory mediators, such as metalloproteases (MMP-13), nitric oxide (NO), and prostaglandin (PGE2) [18]. Various HA compounds are available that differ in molecular weight (MW), composition, and dosage regimens. High MW HA consists of molecules ranging from 3000 kDa to 6000 kDa; medium MW from 1500 to 3000 kDa; low MW has been described as ≤1500 kDa. High molecular weight was proven to increase the fluid retention into the joint and to have greater anti-inflammatory effect than low MW HA [19]. Clearance rate of HA is another important factor influencing its effectiveness. That is why stabilizers have been introduced to slow down the clearance rate. One of the used options is trehalose, a disaccharide that acts as a protector of HA. In an in vitro model hyaluronic acid combined with trehalose had improved resistance to hyaluronidase enzyme compared to standard therapy [20]. Additionally in a randomized controlled trial comparing 1% trehalose hyaluronic acid (T-HA) versus non-trehalose hyaluronic acid (NT-HA) for patients with OA KOOS, VAS and IKDC improved for T-HA group at 6 months post-injection while for NT-HA patients it decreased to baseline. The difference was reported statistically significant (P < 0.05) [21]. At our institution we are currently conducting two clinical trials on the use of new formulations of HA for the treatment of knee OA. Particularly, one consists of a high chain (1800–2600 KDalton) combined with Niacinamide, an excipient that protects the acid from hyaluronidase degradation activity, promoting longer HA stability. Our preliminary results confirm a more durable effect of HA with Niacinamide compared to standard HA in patients affected with knee OA, at 6-month follow-up. We are also evaluating the efficacy of a second product of HA combined with Collagen type I which reinforces the cartilaginous matrix deteriorated by the ongoing pathological processes of osteoarthritis. We are testing it in young athletic patients to evaluate if they can have more benefits when compared with other therapies.

2.3 Adipose stem cells

An Autologous Microfragmented Adipose Tissue (MFAT) and Stromal Vascular Fraction (SVF) in contrast to peripheral blood has 25,000 times more reparative cells [22]. MFAT is acquired from adipose tissue from abdominal or supragluteal area with a special lipoaspirate cannula. Lipoaspirate is transferred to the special low-pressure cylindrical system and combined with saline solution and then mixed. A final product is a concentration of pericytes and MScs. This is then applied into the joint through an injection or during arthroscopy. Promising results have been shown in literature. In multi-centric, international, open-label study evaluating the outcomes of MFAT injections in patients with knee OA at 2-year follow-up significant functional and quality of life improvement was seen in 88% of patients [23]. In a prospective randomized control trial comparing leukocyte-poor PRP combined with HA and MFAT no significant superiority was seen for either group, both procedures were found to be safe with no major complications showing good results at mid-term follow-up [24]. Additionally, a new technique using SVF and platelet-rich plasma to treat knee osteoarthritis (OA) has been recently described. First, the adipose tissue is harvested from abdominal area with the harvester cannula connected to syringe (Figure 1). Meanwhile, leucocyte-poor platelet-rich plasma (LP-PRP) preparation is performed. The harvested fat is transferred to an ACP double syringe for first-round centrifugation with an end product of a middle fraction that is the condensed fatty tissue containing the stromal vascular fraction (SVF) (Figure 2). After fragmentation the lipoaspirate is transferred back to the ACP double syringe for second-round centrifugation. After centrifugation the SVF fraction is retrieved. Lastly the SVF is combined with LP-PRP injected into the patient’s knee joint (Figure 3) [25].

Figure 1.

Lipoaspiration with a 2.1 mm × 15 cm harvester cannula connected to syringe with Johnnie snap locking system through 5 mm skin cut after infiltrating the fatty tissue with a tumescent solution.

Figure 2.

Lipoaspirate transferred into ACP double syringe.

Figure 3.

Injection of the final product, 5 mL of leucocyte-poor platelet-rich plasma (LP-PRP) and 3 mL of SVF in a 10-mL syringe.

2.4 Bone marrow aspirate

MSCs have multi-differentiation ability, which is why they have been identified as an attractive cell source to regenerate tissue. MSC represents only 0.0001 to 0.01% mononuclear cells in bone marrow aspirates [26]. Bone marrow aspirate concentrate (BMAC) consists of variety of growth factors such as the platelet-derived growth factor (PDGF), transforming growth factor-beta (TGF-β), and bone morphogenetic proteins (BMP)-2 and BMP-7, known to have anabolic and anti-inflammatory effects [27]. Hypothetically MSCs, rather than contributing to tissue formation, act as site-regulated “drugs stores” by releasing immunomodulatory factors activated by local injury [28].

BMAC with a Hyaluronic scaffold (Hyaff) has been used to treat chondral lesions of the knee with good clinical outcomes at long-term follow-up using [29, 30, 31]. This treatment was not only successful for single lesions but also in cases of multiple compartment injury, extensive lesions, or in older patients [30, 32, 33]. The composition of BMAC and what could be its mechanism of action has been a point of interest lately. Preliminary data seem to indicate there was no correlation between the clinical outcome and the number of Colony Forming Units (CFU; indirect estimation of the number of MSCs) found in bone marrow aspirate [29]. Interestingly, bone marrow aspirate harvested with Marrow Cellution system was shown to contain a relatively high CFU-fs/mL and CD34+/mL and therefore not requiring centrifugation. The level of CFU-fs/mL was significantly higher in comparison to BMAC in side-by-side evaluation from the same patient [34].

Although the use of BMAC shows good effects in cartilage repair surgery, its use as an injectable therapy is not so common. As a recent RCT has shown, there was no superiority of BMAC over PRP in knee OA therapy [35]. Though BMAC is one of the most appealing sources for cartilage defect repair, several aspects such as safety, amount of aspirate, and scaffold requirement require further investigation.

3. Applications

3.1 Ligament repair

After a ligament is injured, a cascade of processes begins, it is characterized by cellular proliferation, migration, and collagen production. However, the process of platelet fibrin clot formation is significantly deficient in the cases of intra-articular injury [36]. Synovial fluid has been shown to reduce ACL fibroblast proliferation and migration, thus delaying tissue healing [37]. What is more, the presence of circulating plasmin in the joint space has been suggested to be the cause of suboptimal clot formation [38]. Without clot, the torn ligamentous fibers remain separated after injury and subsequent tissue repair is impaired.

PRP contains growth factors that enhance the processes related to cellular activity and their arrival at the area of the lesion. Platelet-derived growth factor (PDGF) and transforming growth factor-β (TGF-β) stimulate cell population’s activation, migration, and proliferation. Fibroblast growth factor (FGF) is vital in collagen synthesis stimulation and fibroblast proliferation, both important elements in the tendon structure [39]. Due to these biological properties, PRP has been suggested to enhance the healing processes in ligaments.

For example, one study showed that the addition of PRP to the sutured ACL repairs did not improve AP knee laxity, maximum tensile load, or linear stiffness of the ACL after 14 weeks in vivo, compared to ACL repair without the addition of PRP [40]. However, when used with a collagen-PRP scaffold, the same author reported a significant improvement in load at yield, maximum load, and linear stiffness at four weeks. The PRP effect alone in ACL repair remains debatable, with significant graft maturation enhancement over time but no clear benefits on clinical outcomes [39].

Mixed results were also found with PRP administration in MCL lesions. LaPrade et al. described that one dose of either PPP or increasing twice the amount of PRP injected at the time of injury did not enhance ligament healing [41]. Furthermore, authors found that a four-time fold increase in the administered dose of PRP showed a significant adverse outcome on ligament strength six weeks after injury. In contrast, in a biomechanical analysis study by Yoshioka et al., there was a significant increase in the structural properties of MCLs in rabbits given leukocyte-poor PRP relative to controls [42].

Other cell therapies reported for ligament healing enhancement included dermal fibroblasts, which were shown to have promising properties in an in vivo models [43]. Adult MSCs represent a known cellular therapy used for tendon engineering; these cells’ self-renewal capacity and multi-lineage differentiation potential have become common treatment. Bone marrow stromal cells embedded on polylactide or glycolide sutures have shown higher collagen production and DNA content than sutures seeded with anterior cruciate ligament fibroblasts and skin fibroblasts [41].

Combinations of cellular isolates and scaffolding have a promising role in treating tendon and ligament injury. In a prospective case series involving 50 patients (mean age 28.3 years), it was shown that ACL primary repair combined with bone marrow stimulation and BMAC-Hyaluronic acid bioabsorbable scaffold is an efficient method to restore knee stability and function in young athletes with acute partial ACL tears, after 10-year of follow-up [44, 45].

3.2 Meniscal repair

Even though techniques of repair have changed, many new instruments have been developed, still in the literature the failure rate of meniscus repair is reported to be around 20–25% [46]. Biological healing enhancement for the meniscal lesions treatment may be one of possible options to alter the outcomes [47].

Possible options for biological enhancement of menisci healing include rasping, needling, using a fibrin clot, platelet-rich plasma, bone marrow aspirate, and a scaffold with bone marrow addition [48].

In the 2019 ESSKA consensus on traumatic meniscus tears rasping, needling, and fibrin clot weak evidence was reported [48]. Although similar conclusion was reached in case of PRP use, a study that was not included in the consensus shown promising results. A prospective, randomized, double-blind, placebo-controlled trial with 37 patients with unstable complete vertical longitudinal tears, half treated with repair and placebo and half with repair and PRP. Same suturing all-inside technique was used. At 18-month follow-up the healing rate of tears was superior in the PRP-treated group (85% versus 47%) [49].

In another study on 550 patients treated for meniscal tears, authors found that the use of PRP resulted in improved survival of isolated meniscal repairs, but had no effect on survival of meniscal repairs with coexisting ACL reconstruction [50].

Bone marrow represents a great potential in healing enhancement. A prospective, randomized, double-blind, parallel-group, placebo-controlled study analyzing complete vertical meniscus tears in 40 patients randomized into two groups both using same suturing technique but one with addition of bone marrow venting procedure. Interestingly, the authors found a significant improvement of healing rate (rated by Second-Look Arthroscopy) in the bone marrow venting group compared to repair alone [51]. Another interesting study by Piontek et al. involved the use of meniscus suture with a collagen membrane wrapping together with bone marrow aspirate to treat combined and complex meniscal tears. They found a statistically significant improvement in subjective scores between the preoperative, 2-year follow-up, and 5-year follow-up [52, 53].

3.3 Healing the cartilage

Bone marrow stimulation techniques refer to methods using bleeding from subchondral marrow space and further formation of fibrin clot, which functions as scaffold for subchondral stem cell migration and consequent formation of fibrocartilage. In general, full-thickness cartilage lesion of a surface area < 1 cm² is considered an indication for a bone marrow stimulation technique as an isolated procedure [54]. Although, one should be aware that these recommendations should be carefully considered for every patient individually.

Microfracture is most commonly known and used procedure due to availability, simplicity, and small cost [55, 56, 57]. The lesion should be prepared, loose cartilage should be removed, and borders made perpendicular to subchondral bone and then holes should be made with an arthroscopic awl. As the saline pressure is lowered, the release of fat droplets and the bleeding begins which will later form a clot on the defect [56, 58, 59]. Studies have shown that this fibrocartilage matrix consists mainly of type I collagen and other non-collagenous proteins, making this tissue more delicate and less elastic, that is why it is common for the initial satisfactory results to deteriorate over long term [60, 61, 62]. Better results may be expected in younger patients with smaller lesions. This technique should be used cautiously as it may damage the subchondral bone and lead to the formation of microcysts, therefore, compromising the articular surface for future procedures [63].

Autologous Matrix-Induced Chondrogenesis (AMIC) is based on the same idea as microfracture but supported with a porcine collagen scaffold [64]. This technique is indicated for focal chondral or osteochondral defects, Outerbridge classification grade 3–4 with a defect size of 1.0–8.0 cm^2, and patient age of 18 to 55 years old [3]. After the defect is treated with microfracture a scaffold is added to cover the lesion and to allow the ingrowth of mesenchymal stem cells (MSCs) from the subchondral bone. The main advantage of the AMIC procedure is no donor site morbidity and the possibility of arthroscopic approach. The procedure is also inexpensive compared to autologous chondrocyte implantation (ACI). Good clinical results of AMIC in mid-term follow-ups have been described [65].

In acute lesions, use of autologous cartilage is an optimal alternative to repair a cartilage defect. It is described that covering an acute cartilage defect with minced fragments from a large piece of cartilage achieves good clinical results [66]. In this technique a large chondral fragment is minced into multiple small ones (<1 x 1 x 1 mm) with a scalpel. First, the cartilage lesion is debrided and drilled into the subchondral bone using a 1.4 mm K-wire. Then, minced cartilage fragments are placed into the defect and attached using fibrin glue. This concept is known since 1980s. The procedure using minced cartilage was modified and combined with various materials to become Cartilage Autograft Implantation System (CAIS) [67]. A cartilage paste (smaller cartilage size) was demonstrated to significantly increase extracellular matrix production [68]. Recently 10–23-year long-term results were reported in 74 patients cured with Articular Cartilage Paste Graft, the biopsies of the healed tissue revealed that 14 (48.3%) contained hyaline-like cartilage, 24 (82.8%) fibrocartilage with GAG, 10 (34.5%) fibrocartilage without GAG, and 3 (10.3%)fibrous tissue [69].

Osteochondral Autograft Transfer System (OATS) may be done in a single-stage procedure, arthroscopically or through arthrotomy. Cylindrical plugs are collected from donor sites from non-articulating regions. The plug consists of not only cartilage but also the subchondral bone, that is why it may recreate the osteochondral unit in cartilage lesions with damaged subchondral bone. This method is one of the few that has the advantage of restoring the hyaline cartilage. OATS is usually used for lesions smaller than 2 cm². In a 17-year prospective multicentric study performed in 383 found good to excellent results in 91% of femoral mosaicplasty, 86% of tibial, and 74% of patellofemoral mosaicplasty [70]. However, Wu et al. have shown that osteochondral plugs protruding 1 mm caused drastically increased contact pressures within the joint. Additionally, treatment using the OAT technique is restricted by the availability of autologous tissue, as donor site morbidity is a concern if multiple grafts are harvested.

Fresh osteochondral allograft is used mostly in lesions where OATS cannot be performed. The advantages of using allografts include the plasticity of graft sizing and the chance to treat the entire lesion with a one transplanted plug and no donor site morbidity. Some disadvantages include lower chondrocyte viability due to storage and managing and potential immunogenic response concerns.

ACI consists of two steps: first, a piece of healthy cartilage is obtained from a non-weight bearing area and subsequently expanded in vitro. The second step is grafting of the chondrocyte suspension into the defect [57]. Four generations of ACI have been introduced through the years. The first generation [71] is based on infusion of the chondrocyte suspension under periosteal flap, while in second generation the chondrocyte suspension is injected under a collagen membrane. The third generation also known as matrix-induced autologous chondrocyte implantation (MACI) is a combination of the expanded chondrocytes embedded on a scaffold which is implanted in the cartilage defect. The fourth generation which is a one-step procedure with chondrocyte isolation through biopsies and direct implantation. Long-term results with ACI first-generation method were published with good term results at 20-year follow-up [72]; However, some studies report significantly better functional outcomes in patients who underwent second-generation ACI compared to patients with first-generation ACI [73, 74] ACI in comparison with bone marrow stimulating techniques such as microfracture has shown to be superior to time due to longer-lasting effects. Although the final tissue is still fibrocartilage, it is more “hyaline-like” in contrast to the one after microfracture procedure [32, 75]. ACI has proven a durable solution in treatment of large full-thickness cartilage lesions, but the need for two surgical interventions, the cost of chondrocyte culture, and equal results compared to one-step biological scaffolds stay the ACI technique’s major drawbacks.

HA-BMAC developed 30 years ago, allows the treatment of larger cartilage lesions in a one-step surgery. This method provided good long-term results [29, 30, 32, 33] and demonstrated its superiority to microfracture. Additionally, it can be used in multiple compartment and extensive lesions or in older patients [30, 32, 33]. The senior authors’ selected method is a one-step cartilage repair with a three-dimensional hyaluronic acid-based scaffold “Hyalofast” (Anika Therapeutics, Bedford, Massachusets, U.S.) combined with activated bone marrow aspirate concentrate (HA-BMAC). Contrasted with two-step MACI, the clinical outcomes have not shown a significant difference and also there was no relationship between the clinical outcome and the number of Colony Forming Units (CFU) found in bone marrow aspirate [29].

Depending on the lesion’s extent and location the procedure is done through a small arthrotomy or arthroscopically. Loose cartilage is removed, vertical walls are made around the periphery of the defect with special chondrectomes. Then the calcified cartilage layer must be thoroughly removed without damaging the subchondral plate (Figure 4A). The defects are measured with aluminum foil templates which are later used to cut out a matching hyaluronic acid scaffold. Bone marrow is collected from the iliac crest and centrifuged to obtain a concentrated bone marrow which is later mixed with Batroxobin (Plateltex®act-Plateltex S.R.O. Bratislava, SK) to create a clot. The hyaluronic acid-based scaffold and clot are combined to create a biologically active structure for cartilage repair. The HA-BMAC is placed on the lesion and secured with fibrin glue (Figure 4B). Afterward, the knee is cycled to check stability [63]. Sadlik et al. demonstrated a variation of this technique using morselized bone graft to fill the lesion and then covered with hyaluronic acid scaffold embedded with BMAC [76].

Figure 4.

(A) chondral defect on the patella after removal of loose cartilage and a calcified layer of subchondral bone with perpendicular borders of the lesion prepared for scaffold implantation. (B) The lesion after implantation of the HA-BMAC secured with fibrin glue.

3.4 Healing the subchondral bone (OCP)

BMAC may as well be used to treat subchondral bone pathologies. Cartilage and subchondral bone work as a unit and over the last few years a debate on the function of subchondral bone has been going on. Bone marrow lesions (BMLs) are the focal defects in the subchondral bone and can be identified by magnetic resonance imaging (MRI). Number of pathologies may be causing such lesions with an ischemic, mechanical or reactive background. When assessing a patient with BML it is vital to evaluate whether the lesion is reversible and irreversible [77]. Both biological and mechanical improvement of osteochondral unit can be achieved with Osteo-Core-Plasty (Marrow Cellution™) a minimally invasive subchondral bone augmentation. This technique may also be used to treat insufficiency fractures, subchondral cysts, and osteonecrosis [78].

This method is made of two parts, first being the aspiration of bone marrow and second application of the material into the defect. Bone marrow is aspirated from the iliac crest. Application may be done arthroscopically or through an open approach, both need fluoroscopic assistance. Necrotic Tissue Zone is recognized under fluoroscopy on AP and lateral images. In an open technique the lesion is debrided, and necrotic bone underneath is separated and removed. In an arthroscopic technique a K-wire is put to target zone from outside the joint and a cannulated drill bit is inserted over the K-Wire. Then Marrow Cellution Bone Core Graft is delivered to the necrotic zone with Extraction/Delivery Tool in both open and arthroscopic approach. The bone core graft is pressed with a probe to aim point. Finally, aspirated Marrow Cellution™ is injected to the necrotic site or in case of an open procedure the Marrow Cellution™ Saturated Matrix Scaffold Membrane is used [79]. In Osteo-Core-Plasty, there is no need for centrifugation and the surgeon can apply the aspirate to the target zone [80].

4. Conclusion

OA is a raising problem and many opportunities to treat cartilage lesions and early OA have been reported. Cell therapies using chondrocytes, MSCs, and other cell sources have been used to treat joint pathologies. In order to obtain the best cartilage quality, these cartilage preserving/regenerating methods combined with addressing coexisting intraarticular pathologies or limb alignment issued. The biology of the articular cartilage must be fully understood before cartilage repair technologies can advance further. Collecting evidence of experimental studies on novel techniques for biological healing is vital to advance the treatment possibilities for patients. Therefore, use of the most appropriate line of treatment and proper patient selection is key to improving results.