Review: Interventions for Cartilage Disease: Current State-of-the-Art and Emerging Technologies

Return to Play After Knee Articular Cartilage Restoration: Surgical Options, Rehabilitation Protocols, and Performance Outcomes

PURPOSE OF REVIEW

Numerous cartilage restoration techniques have proven to be effective in the treatment of articular cartilage defects. The ultimate goal of these procedures is to improve pain and function, thereby increasing the likelihood of a patient's return to physical activity. Postoperative rehabilitation is a key component for a successful and expedient return to activities. The purpose of this article is to review the current literature regarding common surgical options, rehabilitation protocols, and performance outcomes after operative treatment of articular cartilage defects.

RECENT FINDINGS

Studies have demonstrated improved short- to long-term outcomes in a majority of techniques. However, the clinical benefits of microfracture are short-lived, which has led to the use of alternative procedures. Rehabilitation protocols are not standardized, but emphasis has been placed on bracing, weightbearing, early continuous passive range of motion, and strengthening to improve function. There is growing evidence to suggest that accelerated rehabilitation after matrix-induced autologous chondrocyte implantation may result in superior outcomes compared to delayed rehabilitation. Overall, most techniques result in satisfactory rates of return to play, though existing comparative studies typically include patients with heterogeneous pathology, complicating effective synthesis of outcomes data. In appropriately selected patients, cartilage restoration procedures after articular cartilage injury result in favorable patient-reported clinical outcomes and high rates of return to play. While studies emphasize the critical role that rehabilitation plays with respect to outcomes after surgery, there are substantial inconsistencies in protocols across techniques.

Injectable Scaffold with Microfracture using the Autologous Matrix-Induced Chondrogenesis (AMIC) Technique: A Prospective Cohort Study

Introduction

Autologous matrix-induced chondrogenesis (AMIC) is a one-step surgical cartilage repair procedure involving the insertion of a scaffold into the chondral defect after microfracture. BST-CarGel [Smith and Nephew, Watford, England] is an injectable chitosan-based scaffold which can more easily fill defects with irregular shapes and be used to treat vertical or roof chondral lesions. The study aims to evaluate the clinical outcomes of knee cartilage repair with microfracture surgery and BST-CarGel using the AMIC technique for a minimum of two years.

Materials and methods

A prospective study of patients undergoing cartilage repair with microfracture surgery and BST-CarGel at our institution from 2016 to 2019 was performed. Clinical outcomes were determined using the Lysholm Knee Scoring System and Knee Injury and Osteoarthritis Outcome Score (KOOS). These questionnaires were administered before the surgery and at a minimum of two years after surgery.

Results

A total of 21 patients were identified and recruited into the study. 31 cartilage defects were seen and treated in 21 knees. These included horizontal lesions (e.g., trochlear, lateral tibial plateau), vertical lesions (e.g., medial femoral condyle, lateral femoral condyle) and inverted lesions (e.g., patella). No complications or reoperations were seen in our study population. For the average duration of follow-up of 42.5±8.55 months, there was an average improvement in Lysholm score of 25.8±18.6 and an average improvement in KOOS score of 22.5±15.0.

Conclusion

BST-CarGel with microfracture surgery using the AMIC technique is a safe and effective treatment for cartilage defects in the short to medium term.

Anterior Knee Pain: State of the Art

Anterior knee pain (AKP) is one of the most common conditions to bring active young patients to a sports injury clinic. It is a heterogeneous condition related to multiple causative factors. Compared to the general population, there appears to be a higher risk of development of patellofemoral osteoarthritis in patients with AKP. AKP can be detrimental to the patient's quality of life and, in the larger context, significantly burdens the economy with high healthcare costs. This study aims to present a comprehensive evaluation of AKP to improve clinical daily practice. The causes of AKP can be traced not only to structures within and around the knee, but also to factors outside the knee, such as limb malalignment, weakness of specific hip muscle groups, and core and ligamentous laxity. Hence, AKP warrants a pointed evaluation of history and thorough clinical examination, complemented with relevant radiological investigations to identify its origin in the knee and its cause. Conservative management of the condition achieves good results in a majority of patients with AKP. Surgical management becomes necessary only when it is deemed to provide benefit-when the patient has well-characterized structural abnormalities of the knee or limb that correlate with the AKP clinically or in situations where the patient does not obtain significant or sustained relief from symptoms. AKP has a multifactorial etiology. The treatment strategy must be individualized to the patient based on the patient profile and specific cause identified. Hence, treatment of AKP warrants a pointed evaluation of history and thorough clinical examination complemented with relevant radiological investigations to identify the condition's origin and its cause. A holistic approach focused on the patient as a whole will ensure a good clinical outcome, as much as a focus on the joint as the therapeutic target.

The Role of Magnetic Resonance Imaging in Autologous Matrix-Induced Chondrogenesis for Osteochondral Lesions of the Talus: Analyzing MOCART 1 and 2.0

OBJECTIVE

To determine the role of magnetic resonance imaging (MRI) MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) 1 and 2.0 scores in the assessment of postoperative outcome after autologous matrix-induced chondrogenesis (AMIC) for the treatment of osteochondral lesions of the talus (OLTs). It was hypothesized that preoperative patient factors or OLT morphology are associated with postoperative MOCART scores; yet postoperative clinical outcome is not.

STUDY DESIGN

Cohort study; Level of evidence, 4. This study evaluated isolated AMIC that were implanted on the talus of 35 patients for the treatment of symptomatic OLT. Tegner and AOFAS (American Orthopaedic Foot and Ankle Society) scores were obtained at an average follow-up of 4.5 ± 1.8 years and postoperative MRI scored according to the MOCART 1 and 2.0.

RESULTS

OLT size showed significant correlation with postoperative MRI scores (MOCART 1: P = 0.006; MOCART 2.0: P = 0.004). Bone grafting was significantly associated with a MOCART 1 subscale (signal intensity of repair tissue; P = 0.038). Age and defect size showed significant correlations with MOCART 2.0 subscales (P < 0.05). Patients with shorter follow-up had a significantly higher MOCART 1 score and a trend toward better MOCART 2.0 scores than patients with longer follow-up (64.7 vs. 52.9 months, P = 0.02; 69.4 vs. 60.6 months, P = 0.058). No MOCART score was associated with postoperative patient-reported outcomes (n.s.).

CONCLUSION

Osteochondral lesion size is associated with postoperative MOCART scores in patients treated with AMIC for OLTs, with decreasing MOCART scores over time. Yet clinical outcome does not correlate with any MOCART score. Thus, MOCART assessment seems to have no significant role in the postoperative treatment of asymptomatic patients that underwent AMIC for OLTs.

Treating Full Depth Cartilage Defects with Intraosseous Infiltration of Plasma Rich in Growth Factors: An Experimental Study in Rabbits

OBJECTIVE

Intraarticular (IA) administration of platelet-rich plasma (PRP) has been proposed as a new strategy to halt osteoarthritis (OA) progression. In patients with severe OA, its potential is limited because it is unable to reach the subchondral bone, so a new strategy is needed, and intraosseous (IO) infiltration has been suggested. The purpose is to assess the impact of IA together with IO infiltration of plasma rich in growth factors (PRGF) in serum hyaluronic acid (HA) and type II collagen cleavage neoepitope (C2C) levels.

DESIGN

A total of 32 rabbits were included in the study and randomly divided into 2 groups: control and treatment. A 4-mm chondral defect was created in the medial femoral condyle and IA followed by IO infiltration were performed. Serum C2C and HA levels were measured using enzyme-linked immunosorbent assay (ELISA) tests before infiltration and 28, 56, and 84 days post-infiltration.

RESULTS

Significant lower C2C serum levels were obtained in treatment group (IA + IO infiltration of PRGF) at 84 days post-infiltration than in control group (IA infiltration of PRGF + IO infiltration of saline solution), while no significant differences between groups were reported at any other study times. Regarding HA, at 56 days post-infiltration, greater significant levels were seen in the treatment group. However, at 84 days post-infiltration, no significant differences were obtained, although lower levels were reported in the treatment group.

CONCLUSIONS

Despite inconclusive, the results suggest that the combination of IA and IO infiltration with PRGF may enhance cartilage and subchondral bone regeneration, but further studies are needed.

The MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) 2.0 Knee Score and Atlas

OBJECTIVE

Since the first introduction of the MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score, significant progress has been made with regard to surgical treatment options for cartilage defects, as well as magnetic resonance imaging (MRI) of such defects. Thus, the aim of this study was to introduce the MOCART 2.0 knee score - an incremental update on the original MOCART score - that incorporates this progression.

MATERIALS AND METHODS

The volume of cartilage defect filling is now assessed in 25% increments, with hypertrophic filling of up to 150% receiving the same scoring as complete repair. Integration now assesses only the integration to neighboring native cartilage, and the severity of surface irregularities is assessed in reference to cartilage repair length rather than depth. The signal intensity of the repair tissue differentiates normal signal, minor abnormal, or severely abnormal signal alterations. The assessment of the variables "subchondral lamina," "adhesions," and "synovitis" was removed and the points were reallocated to the new variable "bony defect or bony overgrowth." The variable "subchondral bone" was renamed to "subchondral changes" and assesses minor and severe edema-like marrow signal, as well as subchondral cysts or osteonecrosis-like signal. Overall, a MOCART 2.0 knee score ranging from 0 to 100 points may be reached. Four independent readers (two expert readers and two radiology residents with limited experience) assessed the 3 T MRI examinations of 24 patients, who had undergone cartilage repair of a femoral cartilage defect using the new MOCART 2.0 knee score. One of the expert readers and both inexperienced readers performed two readings, separated by a four-week interval. For the inexperienced readers, the first reading was based on the evaluation sheet only. For the second reading, a newly introduced atlas was used as an additional reference. Intrarater and interrater reliability was assessed using intraclass correlation coefficients (ICCs) and weighted kappa statistics. ICCs were interpreted according to Koo and Li; weighted kappa statistics were interpreted according to the criteria of Landis and Koch.

RESULTS

The overall intrarater (ICC = 0.88, P < 0.001) as well as the interrater (ICC = 0.84, P < 0.001) reliability of the expert readers was almost perfect. Based on the evaluation sheet of the MOCART 2.0 knee score, the overall interrater reliability of the inexperienced readers was poor (ICC = 0.34, P < 0.019) and improved to moderate (ICC = 0.59, P = 0.001) with the use of the atlas.

CONCLUSIONS

The MOCART 2.0 knee score was updated to account for changes in the past decade and demonstrates almost perfect interrater and intrarater reliability in expert readers. In inexperienced readers, use of the atlas may improve interrater reliability and, thus, increase the comparability of results across studies.

Trochlear Dysplasia Does Not Affect the Outcomes of Patellofemoral Autologous Chondrocyte Implantation

PURPOSE

To evaluate the influence of trochlear dysplasia on clinical outcomes after autologous chondrocyte implantation (ACI) for the treatment of large cartilage lesions in the patellofemoral joint (PFJ) with a minimum of 2 years' follow-up.

METHODS

We performed a retrospective review of prospectively collected data of all patients submitted to cartilage repair with ACI for focal cartilage defects in the PFJ by a single surgeon. Patient factors, lesion morphology, and preoperative and postoperative patient-reported outcome measures including the Knee Injury and Osteoarthritis Score, Lysholm score, Tegner activity level, and International Knee Documentation Committee Subjective Knee Evaluation Form score were collected. Two independent observers assessed preoperative imaging to determine the presence and grade of trochlear dysplasia. Patients were stratified into 2 groups based on the presence or absence of trochlear dysplasia. Patients without trochlear dysplasia served as controls. Patients were matched 1:1 for sex, age, body mass index, lesion size, and location.

RESULTS

Forty-six patients who underwent ACI in the PFJ with a mean follow-up period of 3.7 ± 1.9 years (range, 2-9 years) were enrolled in this study (23 in the trochlear dysplasia group vs 23 in the normal trochlea group). The patients' mean age was 30.1 ± 8.8 years. Patient-reported outcome measures at final follow-up did not differ between the 2 groups (P > .05). No difference in failure rates was seen between the 2 groups (n = 1 [4.3%] vs n = 1 [4.3%], P > .999). Additionally, no difference in clinical outcomes was seen between patients with high-grade dysplasia (19 patients; Dejour types B-D) and patients without dysplasia (19 patients) (P > .05).

CONCLUSIONS

ACI in the PFJ provides favorable outcomes even in patients with trochlear dysplasia, which are comparable to those in patients with normal trochlear anatomy. Thus, trochlear dysplasia seems to not influence the clinical outcomes of ACI in the PFJ.

LEVEL OF EVIDENCE

Level III, retrospective comparative trial.

Perspectives on Synthetic Materials to Guide Tissue Regeneration for Osteochondral Defect Repair

Regenerative engineering holds the potential to treat clinically pervasive osteochondral defects (OCDs). In a synthetic materials-guided approach, the scaffold's chemical and physical properties alone instruct cellular behavior in order to effect regeneration, referred to herein as "instructive" properties. While this alleviates the costs and off-target risks associated with exogenous growth factors, the scaffold must be potently instructive to achieve tissue growth. Moreover, toward achieving functionality, such a scaffold should also recapitulate the spatial complexity of the osteochondral tissues. Thus, in addition to the regeneration of the articular cartilage and underlying cancellous bone, the complex osteochondral interface, composed of calcified cartilage and subchondral bone, should also be restored. In this Perspective, we highlight recent synthetic-based, instructive osteochondral scaffolds that have leveraged new material chemistries as well as innovative fabrication strategies. In particular, scaffolds with spatially complex chemical and morphological features have been prepared with electrospinning, solvent-casting-particulate-leaching, freeze-drying, and additive manufacturing. While few synthetic scaffolds have advanced to clinical studies to treat OCDs, these recent efforts point to the promising use of the chemical and physical properties of synthetic materials for regeneration of osteochondral tissues.

AMIC-Autologous Matrix-Induced Chondrogenesis Technique in Patellar Cartilage Defects Treatment: A Retrospective Study with a Mid-Term Follow-Up

BACKGROUND

Knee cartilage defects can be retrieved in 60% of patients undergoing knee arthroscopy, especially in the patellofemoral joint. Different techniques have been proposed to treat patellar defects, although most of them are associated with short-term results. In this study Autologous Matrix Induced Chondrogenesis (AMIC), combining subchondral microfractures with a collagen membrane (type I and III collagen), was used in the treatment of isolated patellar cartilage defects.

METHODS

Twenty-four patients were enrolled in this retrospective study. Subjective-International Knee Documentation Committee (IKDC), Visual Analog Scale for Pain (VAS), and Kujala score were collected at 1, 3, 6, and 12 months after surgery, whereas the Tegner Activity Level Scale was determined preoperatively and at final follow-up (final-FU). The same postoperative management and rehabilitation protocol was adopted for all the patients.

RESULTS

Fourteen patients met the inclusion-exclusion criteria and were evaluated at a mean final-FU of 68.2 months (range 25.4-111.2). At 12 months, Kujala, IKDC, and VAS scores significantly increased in comparison to the preoperative assessment, whereas no statistically significant differences were reported between 12 months and final follow-up.

CONCLUSION

This study demonstrated very good results throughout the follow-up, also in sports patients. The AMIC technique, together with an adequate rehabilitation protocol, can be considered as a reliable one-step alternative for the treatment of large isolated patellar cartilage defects.

Tibiofemoral joint structural change from 2.5 to 4.5 years following ACL reconstruction with and without combined meniscal pathology

Background

People who have had anterior cruciate ligament reconstruction (ACLR) are at a high risk of developing tibiofemoral joint (TFJ) osteoarthritis (OA), with concomitant meniscal injury elevating this risk. This study aimed to investigate OA-related morphological change over 2 years in the TFJ among individuals who have undergone ACLR with or without concomitant meniscal pathology and in healthy controls. A secondary aim was to examine associations of baseline TFJ cartilage defects and bone marrow lesions (BML) scores with tibial cartilage volume change in ACLR groups.

Methods

Fifty seven ACLR participants aged 18–40 years (32 isolated ACLR, 25 combined meniscal pathology) underwent knee magnetic resonance imaging (MRI) 2.5 and 4.5 years post-surgery. Nine healthy controls underwent knee MRI at the ~ 2-year intervals. Tibial cartilage volume, TFJ cartilage defects and BMLs were assessed from MRI.

Results

For both ACLR groups, medial and lateral tibial cartilage volume increased over 2 years (P <  0.05). Isolated ACLR group had greater annual percentage increase in lateral tibial cartilage volume compared with controls and with the combined group (P = 0.03). Cartilage defects remained unchanged across groups. Both ACLR groups showed more lateral tibia BML regression compared with controls (P = 0.04). Baseline cartilage defects score was positively associated with cartilage volume increase at lateral tibia (P = 0.002) while baseline BMLs score was inversely related to medial tibia cartilage volume increase (P = 0.001) in the pooled ACLR group.

Conclusions

Tibial cartilage hypertrophy was apparent in ACLR knees from 2.5 to 4.5 years post-surgery and was partly dependent upon meniscal status together with the nature and location of the underlying pathology at baseline. Magnitude and direction of change in joint pathologies (i.e., cartilage defects, BMLs) were less predictable and either remained stable or improved over follow-up.

Electronic supplementary material

The online version of this article (10.1186/s12891-019-2687-9) contains supplementary material, which is available to authorized users.

Rationale and pre-clinical evidences for the use of autologous cartilage micrografts in cartilage repair

BACKGROUND

The management of cartilage lesions is an open issue in clinical practice, and regenerative medicine represents a promising approach, including the use of autologous micrografts whose efficacy was already tested in different clinical settings. The aim of this study was to characterize in vitro the effect of autologous cartilage micrografts on chondrocyte viability and differentiation and perform an evaluation of their application in racehorses affected by joint diseases.

MATERIALS AND METHODS

Matched human chondrocytes and micrografts were obtained from articular cartilage using Rigenera® procedure. Chondrocytes were cultured in the presence or absence of micrografts and chondrogenic medium to assess cell viability and cell differentiation. For the pre-clinical evaluation, three racehorses affected by joint diseases were treated with a suspension of autologous micrografts and PRP in arthroscopy interventions. Clinical and radiographic follow-ups were performed up to 4 months after the procedure.

RESULTS

Autologous micrografts support the formation of chondrogenic micromasses thanks to their content of matrix and growth factors, such as transforming growth factor β (TGFβ) and insulin-like growth factor 1 (IGF-1). On the other hand, no significant differences were observed on the gene expression of type II collagen, aggrecan, and SOX9. Preliminary data in the treatment of racehorses are suggestive of a potential in vivo use of micrografts to treat cartilage lesions.

CONCLUSION

The results reported in this study showed the role of articular micrografts in the promoting chondrocyte differentiation suggesting their potential use in the clinical practice to treat articular lesions.

Silk/Fibroin Microcarriers for Mesenchymal Stem Cell Delivery: Optimization of Cell Seeding by the Design of Experiment

In this methodological paper, lyophilized fibroin-coated alginate microcarriers (LFAMs) proposed as mesenchymal stem cells (MSCs) delivery systems and optimal MSCs seeding conditions for cell adhesion rate and cell arrangement, was defined by a Design of Experiment (DoE) approach. Cells were co-incubated with microcarriers in a bioreactor for different time intervals and conditions: variable stirring speed, dynamic culture intermittent or continuous, and different volumes of cells-LFAMs loaded in the bioreactor. Intermittent dynamic culture resulted as the most determinant parameter; the volume of LFAMs/cells suspension and the speed used for the dynamic culture contributed as well, whereas time was a less influencing parameter. The optimized seeding conditions were: 98 min of incubation time, 12.3 RPM of speed, and 401.5 µL volume of cells-LFAMs suspension cultured with the intermittent dynamic condition. This DoE predicted protocol was then validated on both human Adipose-derived Stem Cells (hASCs) and human Bone Marrow Stem Cells (hBMSCs), revealing a good cell adhesion rate on the surface of the carriers. In conclusion, microcarriers can be used as cell delivery systems at the target site (by injection or arthroscopic technique), to maintain MSCs and their activity at the injured site for regenerative medicine.

Patellofemoral Cartilage Repair

Purpose of Review

This review provides an overview of well-established and newly developed cartilage repair techniques for cartilage defects in the patellofemoral joint (PFJ). An algorithm will be presented for approaching cartilage defects considering the distinct anatomy of both the patellar and trochlear articular surfaces.

Recent Findings

Recent studies on cartilage repair in the PFJ have demonstrated improved outcomes in an attempt to delay or obviate the need for arthroplasty, and improve symptoms in young patients. While autologous chondrocyte implantation shows good and excellent outcomes for chondral lesions, osteochondral defects are adequately addressed with osteochondral allograft transplantation. In case of patellar malalignment, concomitant tibial tubercle osteotomy can significantly improve outcomes. Particulated cartilage and bone marrow aspirate concentrate are potential new alternative treatments for cartilage repair, currently in early clinical studies.

Summary

Due to the frequency of concomitant anatomic abnormalities in the PFJ, a thorough clinical examination combined with careful indication for each procedure in each individual patient combined with meticulous surgical technique is central to achieve satisfying outcomes. Additional comparative studies of cartilage repair procedures, as well as investigation of newer techniques, are needed.

Update on mesenchymal stem cell therapies for cartilage disorders

Cartilage disorders, including focal cartilage lesions, are among the most common clinical problems in orthopedic practice. Left untreated, large focal lesions may result in progression to osteoarthritis, with tremendous impact on the quality of life of affected individuals. Current management strategies have shown only a modest degree of success, while several upcoming interventions signify better outcomes in the future. Among these, stem cell therapies have been suggested as a promising new era for cartilage disorders. Certain characteristics of the stem cells, such as their potential to differentiate but also to support healing made them a fruitful candidate for lesions in cartilage, a tissue with poor healing capacity. The aim of this editorial is to provide an update on the recent advancements in the field of stem cell therapy for the management of focal cartilage defects. Our goal is to present recent basic science advances and to present the potential of the use of stem cells in novel clinical interventions towards enhancement of the treatment armamentarium for cartilage lesions. Furthermore, we highlight some thoughts for the future of cartilage regeneration and repair and to explore future perspectives for the next steps in the field.