Can a biomimetic osteochondral scaffold be a reliable alternative to prosthetic surgery in treating late-stage SPONK?

Multiphasic scaffolds for the repair of osteochondral defects: Outcomes of preclinical studies

Osteochondral defects are caused by injury to both the articular cartilage and subchondral bone within skeletal joints. They can lead to irreversible joint damage and increase the risk of progression to osteoarthritis. Current treatments for osteochondral injuries are not curative and only target symptoms, highlighting the need for a tissue engineering solution. Scaffold-based approaches can be used to assist osteochondral tissue regeneration, where biomaterials tailored to the properties of cartilage and bone are used to restore the defect and minimise the risk of further joint degeneration. This review captures original research studies published since 2015, on multiphasic scaffolds used to treat osteochondral defects in animal models. These studies used an extensive range of biomaterials for scaffold fabrication, consisting mainly of natural and synthetic polymers. Different methods were used to create multiphasic scaffold designs, including by integrating or fabricating multiple layers, creating gradients, or through the addition of factors such as minerals, growth factors, and cells. The studies used a variety of animals to model osteochondral defects, where rabbits were the most commonly chosen and the vast majority of studies reported small rather than large animal models. The few available clinical studies reporting cell-free scaffolds have shown promising early-stage results in osteochondral repair, but long-term follow-up is necessary to demonstrate consistency in defect restoration. Overall, preclinical studies of multiphasic scaffolds show favourable results in simultaneously regenerating cartilage and bone in animal models of osteochondral defects, suggesting that biomaterials-based tissue engineering strategies may be a promising solution.

What Factors are Associated With Conversion to Knee Arthroplasty After Subchondroplasty?

BACKGROUND

Subchondral bone marrow lesions identified on knee MRI are believed to play a role in osteoarthritis-associated pain. The subchondroplasty procedure is an arthroscopically assisted procedure for treating such lesions to avoid larger procedures such as knee arthroplasty. However, the survivorship free of conversion to arthroplasty and the factors associated with an increased likelihood of conversion of subchondroplasty to arthroplasty have not been well defined.

QUESTIONS/PURPOSES

We performed this study to (1) determine the 5-year survivorship of subchondroplasty free from conversion to knee arthroplasty (unicompartmental or total) and (2) identify variables that were associated with progression to knee arthroplasty after a subchondroplasty procedure.

METHODS

In all, 216 patients who underwent a subchondroplasty procedure performed by one surgeon with subchondroplasty experience at a single-center, multilocation facility between September 2014 and August 2017 were retrospectively evaluated to estimate survivorship free from conversion to knee arthroplasty at 5 years. The mean ± SD age and BMI at the time of subchondroplasty procedure were 59 ± 11 years and 33 ± 8 kg/m2, respectively; 60% (129 of 216) of the patients were women. Other variables collected were smoking status and grade and location of chondral lesions. The electronic medical record was reviewed to determine whether the patient had a knee arthroplasty after subchondroplasty. Survivorship free from conversion to knee arthroplasty at 5 years was calculated from a Kaplan-Meier survivorship estimator. Factors associated with progression to knee arthroplasty were examined using t-tests and chi-square analyses. Variables showing evidence of an association with knee arthroplasty were explored further using a Kaplan-Meier survivorship estimator (n = 190).

RESULTS

Kaplan-Meier survivorship free from conversion to knee arthroplasty was 73% (95% CI 67% to 79%) at 5 years after subchondroplasty. We found that age older than 50 years and Grade 4 chondral lesions were associated with conversion to knee arthroplasty. Patients with a Grade 4 chondral lesion had 5-year survivorship of 62% (95% CI 54% to 71%) and 59% (95% CI 50% to 69%) for those older than 50 years with a Grade 4 chondral lesion.

CONCLUSION

Currently, we recommend a detailed, informed discussion of the risks versus benefits with patients who are considering a subchondroplasty procedure, particularly patients aged 50 years and older and those with Grade 4 chondral lesions. Future randomized trials, including those that compare the subchondroplasty procedure with arthroscopy alone or nonoperative management options, are still needed to confirm the efficacy and role of the subchondroplasty procedure in patients with knee osteoarthritis, because only such prospective studies can determine the success of the procedure.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Treatment of Juvenile Knee Osteochondritis Dissecans with a Cell-Free Biomimetic Osteochondral Scaffold: Clinical and MRI Results at Mid-Term Follow-up

OBJECTIVE

Osteochondral surgical procedures have been described for the treatment of unfixable osteochondritis dissecans (OCD), but only few of them have been studied for juvenile OCD (JOCD) lesions. A cell-free biomimetic osteochondral scaffold showed positive results in adult patients. The aim of this study was to evaluate the results of this scaffold for the treatment of knee JOCD at mid-term follow-up.

DESIGN

Twenty patients (14 males, 6 females) were included in this study. Mean age was 16.2 ± 1.4 years, average defect size was 3.2 ± 1.8 cm², and mean symptoms duration was 20.2 ± 17.9 months. After the implantation of the osteochondral collagen-hydroxyapatite scaffold (Maioregen, Fin-Ceramica, Faenza, Italy), patients were evaluated preoperatively and prospectively at 1, 2, and at final mean follow-up of 6 years (range 5-7 years) with International Knee Documentation Committee (IKDC) subjective and objective, Tegner, and EuroQol visual analogue scale (VAS) scores. MRI evaluation was performed with the MOCART 2.0 score.

RESULTS

All scores showed a significant improvement. IKDC subjective score went from 50.3 ± 17.4 preoperative score to 75.3 ± 14.6 at 1 year (P = 0.002), 80.8 ± 14.6 at 2 years and 85.0 ± 9.3 at 6 years. The Tegner score improved from the preoperative evaluation of 2.6 ± 1.4 to 5.5 ± 2.0 at 6 years (P < 0.0005), although without reaching the level registered before the onset of symptoms. A longer symptoms duration influenced negatively IKDC subjective and Tegner scores up to 2 years (P = 0.003 and P = 0.002, respectively) but did not affect the final outcome. Lesion size did not affect the final result. The MOCART 2.0 score showed a significant improvement between 1-year and final follow-up, but with persisting subchondral alterations.

CONCLUSIONS

This study demonstrated a clinical improvement stable over time with a high survival rate, although with persisting abnormal MRI findings, especially at subchondral bone level. This procedure can be considered a suitable option for the treatment of young patients affected by knee OCD. Level of evidence. Case series, level IV.

Cell-free osteochondral scaffolds provide a substantial clinical benefit in the treatment of osteochondral defects at a minimum follow-up of 5 years

Purpose

The treatment of osteochondral lesions is challenging and no consensus has been established about the best option for restoring both cartilage and subchondral bone. Multilayer collagen-hydroxyapatite scaffolds have shown promising clinical results, but the outcome at a follow-up longer than 5 years still has to be proved. The aim was to evaluate the clinical outcome of patients with a knee isolated osteochondral lesion treated with a biomimetic three-layered scaffold at a minimum 5 years of follow-up.

Methods

Twenty-nine patients (23 males and 6 females, mean age 31.5 ± 11.4 years) were evaluated retrospectively before surgery, at 1 and 2 years and at last follow-up (FU). Visual Analog Scale (VAS) for pain, International Knee Documentation Committee (IKDC) Subjective Score, Tegner-Lysholm Knee Scoring Scale and Tegner Activity Level Scale were collected. Mean FU was 7.8 ± 2.0 years (min 5.1 - max 11.3). The etiology of the defect was Osteochondritis Dissecans or osteonecrosis (17 vs 12 cases).

Results

At 12 months FU the IKDC score improved from 51.1 ± 21.7 to 80.1 ± 17.9 (p < 0.01), Tegner Lysholm Score from 59.9 ± 17.3 to 92.5 ± 9.0 (p < 0.01), VAS from 6.1 ± 2.1 to 1.7 ± 2.3 (p < 0.01) and Tegner Activity Level Scale from 1.6 ± 0.5 to 4.9 ± 1.7 (p < 0.01). The results remained stable at 24 months, while at last FU a statistically significant decrease in IKDC, Tegner Lysholm and Tegner Activity Scale was recorded, though not clinically relevant. Patients under 35 achieved statistically better outcomes.

Conclusions

The use of a cell-free collagen-hydroxyapatite osteochondral scaffold provides substantial clinical benefits in the treatment of knee osteochondral lesions at a minimum follow-up of 5 years, especially in patients younger than 35 years.

Level of evidence

Level IV.

Multi-layer cell-free scaffolds for osteochondral defects of the knee: a systematic review and meta-analysis of clinical evidence

Purpose

The aim of this study was to analyze the clinical results provided by multi-layer cell-free scaffolds for the treatment of knee osteochondral defects.

Methods

A systematic review was performed on PubMed, Web of Science, and Cochrane to identify studies evaluating the clinical efficacy of cell-free osteochondral scaffolds for knee lesions. A meta-analysis was performed on articles reporting results of the International Knee Documentation Committee (IKDC) and Tegner scores. The scores were analyzed as improvement from baseline to 1, 2, and ≥ 3 years of follow-up. The modified Coleman Methodology Score was used to assess the study methodology.

Results

A total of 34 studies (1022 patients) with a mean follow-up of 35 months was included. Only three osteochondral scaffolds have been investigated in clinical trials: while TruFit® has been withdrawn from the market for the questionable results, the analysis of MaioRegen and Agili-C™ provided clinical improvements at 1, 2, and ≥ 3 years of follow-up (all significantly higher than the baseline, p < 0.05), although with a limited recovery of the sport-activity level. A low rate of adverse events and an overall failure rate of 7.0% were observed, but the overall evidence level of the available studies is limited.

Conclusions

Multi-layer scaffolds may provide clinical benefits for the treatment of knee osteochondral lesions at short- and mid-term follow-up and with a low number of failures, although the sport-activity level obtained seems to be limited. Further research with high-level studies is needed to confirm the role of multi-layer scaffold for the treatment of knee osteochondral lesions.

The development of natural polymer scaffold-based therapeutics for osteochondral repair

Due to the limited regenerative capacity of cartilage, untreated joint defects can advance to more extensive degenerative conditions such as osteoarthritis. While some biomaterial-based tissue-engineered scaffolds have shown promise in treating such defects, no scaffold has been widely accepted by clinicians to date. Multi-layered natural polymer scaffolds that mimic native osteochondral tissue and facilitate the regeneration of both articular cartilage (AC) and subchondral bone (SCB) in spatially distinct regions have recently entered clinical use, while the transient localized delivery of growth factors and even therapeutic genes has also been proposed to better regulate and promote new tissue formation. Furthermore, new manufacturing methods such as 3D bioprinting have made it possible to precisely tailor scaffold micro-architectures and/or to control the spatial deposition of cells in requisite layers of an implant. In this way, natural and synthetic polymers can be combined to yield bioactive, yet mechanically robust, cell-laden scaffolds suitable for the osteochondral environment. This mini-review discusses recent advances in scaffolds for osteochondral repair, with particular focus on the role of natural polymers in providing regenerative templates for treatment of both AC and SCB in articular joint defects.

Repair of large condylar osteochondral defects of the knee by collagen scaffold. Minimum two-year outcomes

INTRODUCTION

Collagen scaffolds are a good surgical option for covering large focal osteochondral defects in the knee. In the recent literature there is a wide range of patient profiles and chondral defect treatments (chondral and osteochondral defects, associated procedures, etc.). The aim of the present study was to evaluate clinical and imaging outcomes with collagen scaffolds and to assess any correlation between medium-term clinical outcome and MRI features. The hypothesis was that there is no correlation between clinical outcome and MRI after 2 years postoperatively.

MATERIAL AND METHODS

A single-center retrospective observational study included all patients receiving a MaioRegen® scaffold for large painful focal osteochondral defect of the femoral condyle. There were 17 patients, with a mean age of 28±9 years. Defect locations comprised 12 medial femoral condyles, 4 lateral femoral condyles and 1 lateral tibial plateau. Mean defect area was 4.5±1.4cm². All patients were evaluated clinically and on KOOS and objective and subjective IKDC scales, with MRI at last follow-up.

RESULTS

At a mean follow-up of 46±17 months, mean subjective IKDC was 67.8±23; KOOS scores were: symptoms, 78±22; pain, 78±23; function, 85±20; sports, 66±27; and activities of daily living, 59±25. MRI MOCART score revealed incomplete scaffold healing in 21.4% of cases, with variable signal intensity within regenerated tissue. Functional scores did not correlate with reconstruction aspect on MRI.

DISCUSSION/CONCLUSION

3D collagen scaffolds yield good medium-term clinical outcomes in large osteochondral defects of the knee. There is, however, a discrepancy between MRI features of the recipient site and objective and subjective clinical scores. These scaffolds may be a good option for treating large focal osteochondral defects in knees of young patients, but MRI does not provide satisfactory medium-term assessment.

Cell-Free Osteochondral Scaffold for the Treatment of Focal Articular Cartilage Defects in Early Knee OA: 5 Years' Follow-Up Results

The purpose of this study was to investigate the clinical results at five years' follow-up of a tri-layered nanostructured biomimetic osteochondral scaffold used for focal articular cartilage defects in patients meeting the criteria of early osteoarthritis (EOA). The study population comprised 22 patients (mean age: 39 years), prospectively assessed before surgery, at 24 and 60 months' follow-up. Inclusion criteria were: at least two episodes of knee pain for more than 10 days in the last year, Kellgren-Lawrence OA grade 0, I or II and arthroscopic or MRI findings according to the European Society of Sports Traumatology, Knee Surgery & Arthroscopy (ESSKA) criteria. Clinical results demonstrated significant improvement in International Knee Documentation Committee (IKDC) subjective and objective scores and in Tegner score, although activity level never reached the pre-injury level. The complication rate of this study was 8.3%. Two patients underwent re-operation (8.3%), while a comprehensive definition of failure (including both surgical and clinical criteria) identified four failed patients (16.6%) at this mid-term follow-up evaluation. The use of a free-cell osteochondral scaffold represented a safe and valid alternative for the treatment of focal articular cartilage defects in the setting of an EOA, and was able to permit a significant clinical improvement and stable outcome with low complication and failure rates.

Cell-Free Biomimetic Osteochondral Scaffold: Implantation Technique

This 1-stage cell-free scaffold-based technique is indicated for the treatment of full-thickness chondral and osteochondral lesions in the knee, regardless of the lesion size. The aim of the procedure is restoration of the osteochondral unit while avoiding the issues of donor site morbidity and those related to cell management.

Description

The surgical technique is simple and can be performed as a 1-stage procedure. The lesion site is visualized through a standard knee medial or lateral parapatellar arthrotomy. The defect is prepared by excision of the injured cartilage and subchondral bone to ensure adequate bone-marrow blood flow and to create a squared, regularly shaped lodging for the device. The scaffold is then shaped and sized according to the dimensions of the prepared lesion site and implanted by press-fitting or with addition of fibrin glue. Finally, the complete range of motion is tested to assess the stability of the implant before and after releasing the tourniquet.

Alternatives

Nonsurgical alternatives have been reported to include nonpharmacological modalities, such as dietary supplements, and pharmacological therapies as well as physical therapies and novel biological procedures involving injections of various substances¹. There are several surgical alternatives, including among others microfracture, mosaicplasty, osteochondral allograft, and total knee arthroplasty, depending primarily on the disease stage and etiology as well as the specific patient conditions^2,3.

Rationale

This cell-free device is engineered in 3 layers to mimic the structure and composition of the osteochondral unit in order to guide resident cells toward an ordered regeneration of both bone and cartilage layers, providing a better quality of regenerated articular surface. The treatment approach offers a useful alternative to current procedures in the field of osteochondral lesions, in particular for young and middle-aged patients affected by symptomatic defects in which subchondral bone is likely involved. The advantages of this scaffold include the ability to perform a 1-stage surgical procedure, off-the-shelf availability, a straightforward surgical technique, and lower costs compared with cell-based regenerative options. Furthermore, in contrast to some more traditional treatments, it can be used for large lesions.

Treatment of unstable knee osteochondritis dissecans in the young adult: results and limitations of surgical strategies-The advantages of allografts to address an osteochondral challenge

Joint surface incongruence resulting from osteochondritis dissecans (OCD) alters the articular physiologic congruence, increasing the contact stress on adjacent joint surfaces and accelerating wear and the cascade of joint degeneration. Accordingly, the restoration of articular surface integrity is of major importance, especially in young adults where, in lesions left untreated or following simple fragment excision, early osteoarthritis can be anticipated. Therefore, the treatment algorithm in unstable knee OCD of the young adult foresees surgical options to restore the articular surface. Several procedures have been proposed, including refixation of the detached fragment bone marrow stimulation, osteochondral autograft implantation, fresh osteochondral allograft transplantation, and cell-based or cell-free regenerative techniques. The aim of this review was to summarize the evidence for these surgical strategies, reporting their results and limitations. The overall evidence documents positive results for each of the assorted surgical procedures applied to treat unstable OCD, thus indicating support for their selected use to treat osteochondral defects paying particular attention to their specific indications for the lesion characteristics. The fixation of a good quality fragment should be pursued as a first option, while unfixable small lesions may benefit from autografts. For large lesions, available cell-based or cell-free osteochondral scaffold are a feasible solution but with limitation in terms of regenerated tissue quality. In this light, fresh allografts may offer articular surface restoration with viable physiologic osteochondral tissue providing a predictably successful outcome, and therefore they may currently represent the most suitable option to treat unstable irreparable OCD lesion in young adults. LEVEL OF EVIDENCE: V.

MaioRegen Osteochondral Substitute for the Treatment of Knee Defects: A Systematic Review of the Literature

BACKGROUND

This study aims to investigate the clinical and radiological efficacy of three-dimensional acellular scaffolds (MaioRegen) in restoring osteochondral knee defects.

METHODS

MEDLINE, Scopus, CINAHL, Embase, and Cochrane Databases were searched for articles in which patients were treated with MaioRegen for osteochondral knee defects.

RESULTS

A total of 471 patients were included in the study (mean age 34.07 ± 5.28 years). The treatment involved 500 lesions divided as follows: 202 (40.4%) medial femoral condyles, 107 (21.4%) lateral femoral condyles, 28 (5.6%) tibial plateaus, 46 (9.2%) trochleas, 74 (14.8%) patellas, and 43 (8.6%) unspecified femoral condyles. Mean lesion size was 3.6 ± 0.85 cm². Only four studies reported a follow-up longer than 24 months. Significant clinical improvement has been reported in almost all studies with further improvement up to 5 years after surgery. A total of 59 complications were reported of which 52 (11.1%) experienced minor complications and 7 (1.48%) major complications. A total of 16 (3.39%) failures were reported.

CONCLUSION

This systematic review describes the current available evidence for the treatment of osteochondral knee defects with MaioRegen Osteochondral substitute reporting promising satisfactory and reliable results at mid-term follow-up. A low rate of complications and failure was reported, confirming the safety of this scaffold. Considering the low level of evidence of the study included in the review, this data does not support the superiority of the Maioregen in terms of clinical improvement at follow-up compared to conservative treatment or other cartilage techniques.

Use of a Biomimetic Scaffold for the Treatment of Osteochondral Lesions in Early Osteoarthritis

The aim of this study is to investigate clinical and radiographic outcomes of a biomimetic scaffold for the treatment of osteochondral knee lesions in patients with early OA. Study population was represented by 26 patients with a mean age of 44 years affected by early OA. Inclusion criteria were two episodes of knee pain for more than 10 days in the last year, Kellgren-Lawrence OA grade 0 or I or II, and arthroscopic findings of cartilage defects. Nineteen patients had a previous surgery, 11 of which were revision surgeries of osteochondral unit. All patients were treated with a biomimetic scaffold with a tri-layered structure of type I equine collagen and magnesium-enriched hydroxyapatite. Clinical outcomes were evaluated using the IKDC, Lysholm, VAS, KOOS, and Tegner scores at baseline and at an average follow-up of 35 months. Magnetic resonance imaging (MRI) was performed at follow-up time in 19 patients. Clinical outcomes showed significant improvement in VAS, Lysholm, IKDC subjective score, and KOOS subscales in 69% of the patients. Complication rate of this cases series was 11%, with no surgical failure, although 31% of patients did not reach a significant improvement and were thus considered as clinical failure. MRI analysis showed integration of the scaffold only in 47% of the patients, with partial regeneration of the subchondral bone. No correlation between clinics and radiological images was found. The use of a biomimetic osteochondral scaffold in the setting of an early OA, alone or associated with other procedures, appeared to be a valid and safe option, able to provide good and stable clinical outcomes with high patient's satisfaction and low complication rate.