Osteochondral scaffold reconstruction for complex knee lesions: a comparative evaluation

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.

Fabricating the cartilage: recent achievements

This review aims to describe the most recent achievements and provide an insight into cartilage engineering and strategies to restore the cartilage defects. Here, we discuss cell types, biomaterials, and biochemical factors applied to form cartilage tissue equivalents and update the status of fabrication techniques, which are used at all stages of engineering the cartilage. The actualized concept to improve the cartilage tissue restoration is based on applying personalized products fabricated using a full cycle platform: a bioprinter, a bioink consisted of ECM-embedded autologous cell aggregates, and a bioreactor. Moreover, in situ platforms can help to skip some steps and enable adjusting the newly formed tissue in the place during the operation. Only some achievements described have passed first stages of clinical translation; nevertheless, the number of their preclinical and clinical trials is expected to grow in the nearest future.

A dual functional chondro-inductive chitosan thermogel with high shear modulus and sustained drug release for cartilage tissue engineering

We report a chitosan-based nanocomposite thermogel with superior shear modulus resembling that of cartilage and dual pro-chondrogenic and anti-inflammatory functions. Two therapeutic agents, kartogenin (KGN) and diclofenac sodium (DS), are employed to promote chondrogenesis of stem cells and suppress inflammation, respectively. To extend the release time in a controlled manner, KGN is encapsulated in the uniform-sized starch microspheres and DS is loaded into the halloysite nanotubes. Both drug carriers are doped into the maleimide-modified chitosan hydrogel to produce a shear modulus of 167 ± 5 kPa that is comparable to that of articular cartilage (50-250 kPa). Owing to the hydrogel injectability and relatively suitable gelation time (5 ± 0.5 min) at 37 °C, this system potentially constitutes a manageable platform for clinical practice. Moreover, sustained linear drug release for over a month boosts chondro-differentiation of stem cells to eliminate the necessity for multiple administrations. Considering virtues such as thermogel strength and ability to co-deliver anti-inflammatory and chondro-inductive biomolecules continuously, the materials and strategy have promising potential in functional cartilage tissue engineering.

Cell-Free Biomimetic Osteochondral Scaffold for the Treatment of Knee Lesions: Clinical and Imaging Results at 10-Year Follow-up

BACKGROUND

Cell-free devices have been introduced to restore osteochondral defects, avoiding the limitations of cell-based procedures. Among these, an osteochondral scaffold made of type I collagen and hydroxyapatite has been investigated with promising results up to medium-term follow-up. However, the clinical and imaging results over time still need to be documented.

PURPOSE

To evaluate the clinical outcome and tissue maturation at long-term follow-up after the implantation of the osteochondral scaffold.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 24 patients (7 women, 17 men; age, 36 ± 9.5 years) underwent surgical implantation of the osteochondral scaffold and were prospectively evaluated before surgery, at 2-, 5-, and 10-year follow-up. The mean defect size was 2.9 ± 1.4 cm². Patients were evaluated using the International Knee Documentation Committee (IKDC) subjective and objective scores, and the activity level was documented with the Tegner score. Magnetic resonance imaging (MRI) evaluation involved the use of the magnetic resonance observation of cartilage repair tissue score combined with 5 more variables focused on the bone layer.

RESULTS

A statistically significant improvement of all clinical scores was documented from the baseline to the final evaluation. The IKDC subjective score improved from the preoperative level to 2 years (41 ± 13.2 and 77.1 ± 14.6, respectively) (P < .0005), with stable results up to 10 years (77.4 ± 19.4). The IKDC objective score changed from 52% of normal and nearly normal knees before the treatment to 84% at 10 years (P < .0005). Tegner sports activity at the final evaluation (3.8 ± 1.7) was higher compared with the preoperative level (1.6 ± 1.1; P < .05), but it remained significantly lower compared with the preinjury level (5.5 ± 2.6; P < .05). Treatment failed in 1 patient. Persisting graft alterations were observed on MRI scans, although without correlating with the clinical outcome.

CONCLUSION

The regenerative potential of this scaffold is limited, as demonstrated by the signal alterations persisting over time on MRI scans. On the other hand, the clinical improvement was significant and stable over time both in terms of subjective and objective outcomes, including activity level, with overall good results.

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.

A case report of femoral head fracture with osteochondral lesion treated by osteosynthesis and biomimetic scaffold: 2-year clinical and radiological follow-up

The aim of the present study was to present clinical and radiological outcome of a hip fracture-dislocation of the femoral head treated with biomimetic osteochondral scaffold.

An 18-year-old male was admitted to the hospital after a motorcycle-accident. He presented with an obturator hip dislocation with a type IVA femoral head fracture according to Brumback classification system. The patient underwent surgery 5 days after accident. The largest osteochondral fragment was reduced and stabilized with 2 screws, and the small fragments were removed. The residual osteochondral area was replaced by a biomimetic nanostructured osteochondral scaffold. At 1-year follow-up the patient did not complain of hip pain and could walk without limp. At 2-year follow-up he was able to run with no pain and he returned to practice sports. Repeated radiographs and magnetic resonance imaging studies of the hip showed no signs of osteoarthritis or evidence of avascular necrosis. A hyaline-like signal on the surface of the scaffold was observed with restoration of the articular surface and progressive decrease of the subchondral edema.

The results of the present study showed that the biomimetic nanostructured osteochondral scaffold could be a promising and safe option for the treatment of traumatic osteochondral lesions of the femoral head.

Study Design: Case report.

The effect of a micro-visual intervention on the accelerated recovery of patients with kinesiophobia after total knee replacement during neo-coronary pneumonia

BACKGROUND

The global neo-coronary pneumonia epidemic has increased the workload of healthcare institutions in various countries and directly affected the physical and psychological recovery of the vast majority of patients requiring hospitalization in China. We anticipate that post-total knee arthroplasty kinesiophobia may have an impact on patients' postoperative pain scores, knee function, and ability to care for themselves in daily life. The purpose of this study is to conduct a micro-video intervention via WeChat to verify the impact of this method on the rapid recovery of patients with kinesiophobia after total knee arthroplasty during neo-coronary pneumonia.

METHODS

Using convenience sampling method, 78 patients with kinesiophobia after artificial total knee arthroplasty who met the exclusion criteria were selected and randomly grouped, with the control group receiving routine off-line instruction and the intervention group receiving micro-video intervention, and the changes in the relevant indexes of the two groups of patients at different time points on postoperative day 1, 3 and 7 were recorded and analyzed.

RESULTS

There were no statistical differences in the scores of kinesiophobia, pain, knee flexion mobility (ROM) and ability to take care of daily life between the two groups on the first postoperative day (P > .05). On postoperative day 3 and 7, there were statistical differences in Tampa Scale for kinesiophobia, pain, activities of daily living scale score and ROM between the two groups (P < .01), and the first time of getting out of bed between the two groups (P < .05), and by repeated-measures ANOVA, there were statistically significant time points, groups and interaction effects of the outcome indicators between the 2 groups (P < .01), indicating that the intervention group reconstructed the patients' postoperative kinesiophobiaand hyperactivity. The level of pain awareness facilitates the patient's acquisition of the correct functional exercises to make them change their misbehavior.

CONCLUSIONS

WeChat micro-video can reduce the fear of movement score and pain score in patients with kinesiophobia after unilateral total knee arthroplasty, shorten the first time out of bed, and improve their joint mobility and daily living ability.

ETHICS

This study has passed the ethical review of the hospital where it was conducted and has been filed, Ethics Approval Number: 20181203-01.

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.

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.

A Composite Chitosan-Reinforced Scaffold Fails to Provide Osteochondral Regeneration

Several biomaterials have recently been developed to address the challenge of osteochondral regeneration. Among these, chitosan holds promises both for cartilage and bone healing. The aim of this in vivo study was to evaluate the regeneration potential of a novel hybrid magnesium-doped hydroxyapatite (MgHA), collagen, chitosan-based scaffold, which was tested in a sheep model to ascertain its osteochondral regenerative potential, and in a rabbit model to further evaluate its ability to regenerate bone tissue. Macroscopic, microtomography, histology, histomorphometry, and immunohistochemical analysis were performed. In the sheep model, all analyses did not show significant differences compared to untreated defects (p > 0.05), with no evidence of cartilage and subchondral bone regeneration. In the rabbit model, this bone scaffold provided less ability to enhance tissue healing compared with a commercial bone scaffold. Moreover, persistence of scaffold material and absence of integration with connective tissue around the scaffolds were observed. These results raised some concerns about the osteochondral use of this chitosan composite scaffold, especially for the bone layer. Further studies are needed to explore the best formulation of chitosan-reinforced composites for osteochondral treatment.

Reconstructing Bone with Natural Bone Graft: A Review of In Vivo Studies in Bone Defect Animal Model

Bone defects caused by fracture, disease or congenital defect remains a medically important problem to be solved. Bone tissue engineering (BTE) is a promising approach by providing scaffolds to guide and support the treatment of bone defects. However, the autologous bone graft has many defects such as limited sources and long surgical procedures. Therefore, xenograft bone graft is considered as one of the best substitutions and has been effectively used in clinical practice. Due to better preserved natural bone structure, suitable mechanical properties, low immunogenicity, good osteoinductivity and osteoconductivity in natural bone graft, decellularized and demineralized bone matrix (DBM) scaffolds were selected and discussed in the present review. In vivo animal models provide a complex physiological environment for understanding and evaluating material properties and provide important reference data for clinical trials. The purpose of this review is to outline the in vivo bone regeneration and remodeling capabilities of decellularized and DBM scaffolds in bone defect models to better evaluate the potential of these two types of scaffolds in BTE. Taking into account the limitations of the state-of-the-art technology, the results of the animal bone defect model also provide important information for future design of natural bone composite scaffolds.

Novel alginate biphasic scaffold for osteochondral regeneration: an in vivo evaluation in rabbit and sheep models

Current therapeutic strategies for osteochondral restoration showed a limited regenerative potential. In fact, to promote the growth of articular cartilage and subchondral bone is a real challenge, due to the different functional and anatomical properties. To this purpose, alginate is a promising biomaterial for a scaffold-based approach, claiming optimal biocompatibility and good chondrogenic potential. A previously developed mineralized alginate scaffold was investigated in terms of the ability to support osteochondral regeneration both in a large and medium size animal model. The results were evaluated macroscopically and by microtomography, histology, histomorphometry, and immunohistochemical analysis. No evidence of adverse or inflammatory reactions was observed in both models, but limited subchondral bone formation was present, together with a slow scaffold resorption time.The implantation of this biphasic alginate scaffold provided partial osteochondral regeneration in the animal model. Further studies are needed to evaluate possible improvement in terms of osteochondral tissue regeneration for this biomaterial.

A multilayer biomaterial for osteochondral regeneration shows superiority vs microfractures for the treatment of osteochondral lesions in a multicentre randomized trial at 2 years

PURPOSE

The increasing awareness on the role of subchondral bone in the etiopathology of articular surface lesions led to the development of osteochondral scaffolds. While safety and promising results have been suggested, there are no trials proving the real potential of the osteochondral regenerative approach. Aim was to assess the benefit provided by a nanostructured collagen-hydroxyapatite (coll-HA) multilayer scaffold for the treatment of chondral and osteochondral knee lesions.

METHODS

In this multicentre randomized controlled clinical trial, 100 patients affected by symptomatic chondral and osteochondral lesions were treated and evaluated for up to 2 years (51 study group and 49 control group). A biomimetic coll-HA scaffold was studied, and bone marrow stimulation (BMS) was used as reference intervention. Primary efficacy measurement was IKDC subjective score at 2 years. Secondary efficacy measurements were: KOOS, IKDC Knee Examination Form, Tegner and VAS Pain scores evaluated at 6, 12 and 24 months. Tissue regeneration was evaluated with MRI MOCART scoring system at 6, 12 and 24 months. An external independent agency was involved to ensure data correctness and objectiveness.

RESULTS

A statistically significant improvement of all clinical scores was obtained from basal evaluation to 2-year follow-up in both groups, although no overall statistically significant differences were detected between the two treatments. Conversely, the subgroup of patients affected by deep osteochondral lesions (i.e. Outerbridge grade IV and OCD) showed a statistically significant better IKDC subjective outcome (+12.4 points, p = 0.036) in the coll-HA group. Statistically significant better results were also found for another challenging group: sport active patients (+16.0, p = 0.027). Severe adverse events related to treatment were documented only in three patients in the coll-HA group and in one in the BMS group. The MOCART score showed no statistical difference between the two groups.

CONCLUSIONS

This study highlighted the safety and potential of a biomimetic implant. While no statistically significant differences were found compared to BMS for chondral lesions, this procedure can be considered a suitable option for the treatment of osteochondral lesions.

LEVEL OF EVIDENCE

I.

Hydrogels for Cartilage Regeneration, from Polysaccharides to Hybrids

The aims of this paper are: (1) to review the current state of the art in the field of cartilage substitution and regeneration; (2) to examine the patented biomaterials being used in preclinical and clinical stages; (3) to explore the potential of polymeric hydrogels for these applications and the reasons that hinder their clinical success. The studies about hydrogels used as potential biomaterials selected for this review are divided into the two major trends in tissue engineering: (1) the use of cell-free biomaterials; and (2) the use of cell seeded biomaterials. Preparation techniques and resulting hydrogel properties are also reviewed. More recent proposals, based on the combination of different polymers and the hybridization process to improve the properties of these materials, are also reviewed. The combination of elements such as scaffolds (cellular solids), matrices (hydrogel-based), growth factors and mechanical stimuli is needed to optimize properties of the required materials in order to facilitate tissue formation, cartilage regeneration and final clinical application. Polymer combinations and hybrids are the most promising materials for this application. Hybrid scaffolds may maximize cell growth and local tissue integration by forming cartilage-like tissue with biomimetic features.

Clinical and imaging outcome of osteochondral lesions of the talus treated using autologous matrix-induced chondrogenesis technique with a biomimetic scaffold

BACKGROUND

The purpose of our study was to assess the clinical and imaging outcome of autologous matrix-induced chondrogenesis (AMIC) technique consisting of microfractures followed by the filling of osteochondral lesions of the talus (OLTs) with a cell-free biphasic collagen-hydroxyapatite osteochondral scaffold (MaioRegen).

METHODS

Sixteen patients (eight males, age: 42.6 ± 18.4, range 14-74) with OLT repaired using AMIC technique, with implantation of MaioRegen, were clinically evaluated through the American Orthopedic Foot and Ankle Society Score (AOFAS) and a 10-point Visual Analogue Scale (VAS) pain score after a mean follow-up of 30 ± 16.9 months. The MRI examinations were performed 12 and 24 months after surgery. A paired t-test was applied to compare pre- and post-operative clinical findings (VAS and AOFAS) and Magnetic resonance observation of cartilage repair tissue (MOCART) score changes in the follow-up. To assess the correlation between variation of AOFAS and MOCART scores, the Pearson's correlation coefficient was calculated.

RESULTS

No complications after surgery were encountered. From pre-operative to post-operative values, there was a significant (P < 0.001) reduction of mean VAS pain score (6.3 ± 0.9,range: 4-8 and 2.9 ± 1.8,range: 0-6, respectively) and increase of AOFAS score (60.2 ± 7.8,range: 50-74 and 77.4 ± 16.2,range: 50-100, respectively). Among 16 patients, six (37%) were not satisfied at the end of follow-up, six (37%) were moderately satisfied and four (25%) were highly satisfied. The treatment was considered failed in five out of 16 patients (31%). Among them, four (25%) required re-interventions with implantation of ankle prostheses, whereas one patient was treated with a further AMIC technique combined with autologous bone graft and platelet-rich plasma. The mean MOCART score was 41.9 ± 14.6 (25-70) 12 months after surgery and 51.9 ± 11.6 (30-70) after 24 months, with a statistically significant increase (P = 0.012). However, no correlation was seen between AOFAS and MOCART changes (r = 0.215, p = 0.609).

CONCLUSION

The high rates of treatment failure encountered in our study using MaioRegen need to be confirmed by larger studies and should induce the scientific community questioning the reliability of this biomimetic scaffold for the treatment of OLTs.

One-Step Treatment for Patellar Cartilage Defects With a Cell-Free Osteochondral Scaffold: A Prospective Clinical and MRI Evaluation

BACKGROUND

The treatment of symptomatic cartilage defects of the patella is particularly challenging, and no gold standard is currently available.

PURPOSE

To evaluate the clinical results of a biphasic cell-free collagen-hydroxyapatite scaffold and to evaluate osteochondral tissue regeneration with magnetic resonance imaging (MRI).

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Thirty-four patients (18 men and 16 women; mean ± SD: age, 30.0 ± 10 years) were treated by scaffold implantation for knee chondral or osteochondral lesions of the patella (area, 2.1 ± 1 cm²). The clinical evaluation was performed prospectively at 12 and 24 months via the IKDC (International Knee Documentation Committee; objective and subjective) and Tegner scores. MRI evaluation was performed at both follow-ups in 18 lesions through the MOCART score (magnetic resonance observation of cartilage repair tissue) and specific subchondral bone parameters.

RESULTS

A statistically significant improvement in all the scores was observed at 12- and 24-month follow-up as compared with the basal evaluation. The IKDC subjective score improved from 39.5 ± 14.5 to 61.9 ± 14.5 at 12 months ( P > .0005) with a further increase to 67.6 ± 17.4 at 24 months of follow-up (12-24 months, P = .020). The MRI evaluation showed a stable value of the MOCART score between 12 and 24 months, with a complete filling of the cartilage in 87.0% of the lesions, complete integration of the graft in 95.7%, and intact repair tissue surface in 69.6% at final follow-up. The presence of osteophytes or more extensive bony overgrowth was documented in 47.8% of the patients of this series, but no correlation was found between MRI findings and clinical outcome.

CONCLUSION

The implantation of a cell-free collagen-hydroxyapatite osteochondral scaffold provided a clinical improvement at short-term follow-up for the treatment of patellar cartilage defects. Women had lower outcomes, and the need for realignment procedures led to a slower recovery. MRI evaluation showed some abnormal findings with the presence of bone overgrowth, but no correlation has been found with the clinical outcome.

Tibial Allograft Transfer for Medial Tibial Plateau Resurfacing

A large cartilage lesion of the tibial plateau with a deficient meniscus in a young patient is a challenging pathology for the orthopaedic surgeon due to the limited options available. While hemiarthroplasty procedures can be an option, the risk of revision in a young patient is high, and therefore a reconstructive procedure is advocated. The purpose of this Technical Note is to describe our technique for tibial plateau resurfacing, including the preparation and implantation of a medial tibial plateau and medial meniscal allograft, in a patient with a post-traumatic KD-4 knee dislocation with a medial tibial plateau rim fracture, medial meniscus deficiency, and medial tibiofemoral joint subluxation.

Tri-layered composite plug for the repair of osteochondral defects: in vivo study in sheep

Cartilage defects are a source of pain, immobility, and reduced quality of life for patients who have acquired these defects through injury, wear, or disease. The avascular nature of cartilage tissue adds to the complexity of cartilage tissue repair or regeneration efforts. The known limitations of using autografts, allografts, or xenografts further add to this complexity. Autologous chondrocyte implantation or matrix-assisted chondrocyte implantation techniques attempt to introduce cultured cartilage cells to defect areas in the patient, but clinical success with these are impeded by the avascularity of cartilage tissue. Biodegradable, synthetic scaffolds capable of supporting local cells and overcoming the issue of poor vascularization would bypass the issues of current cartilage treatment options. In this study, we propose a biodegradable, tri-layered (poly(glycolic acid) mesh/poly(l-lactic acid)-colorant tidemark layer/collagen Type I and ceramic microparticle-coated poly(l-lactic acid)-poly(ϵ-caprolactone) monolith) osteochondral plug indicated for the repair of cartilage defects. The porous plug allows the continual transport of bone marrow constituents from the subchondral layer to the cartilage defect site for a more effective repair of the area. Assessment of the in vivo performance of the implant was conducted in an ovine model (n = 13). In addition to a control group (no implant), one group received the implant alone (Group A), while another group was supplemented with hyaluronic acid (0.8 mL at 10 mg/mL solution; Group B). Analyses performed on specimens from the in vivo study revealed that the implant achieves cartilage formation within 6 months. No adverse tissue reactions or other complications were reported. Our findings indicate that the porous biocompatible implant seems to be a promising treatment option for the cartilage repair.

Morphological characteristics of cartilage-bone transitional structures in the human knee joint and CAD design of an osteochondral scaffold

Background

There is a lack of understanding of the morphological characteristics of the cartilage-bone interface. Materials that are currently being used in tissue engineering do not adequately support the regeneration of bone and cartilage tissues. The present study aimed to explore the morphological characteristics of cartilage-bone transitional structures in the human knee joint and to design a biomimetic osteochondral scaffold based on morphological data.

Methods

Histology, micro-computed tomography (micro-CT), and scanning electron microscopy (SEM) were used to investigate the microstructure of the cartilage-bone transitional structures. Morphological characteristics and their distribution were obtained and summarized into a biomimetic design. A three-dimensional model of a biomimetic osteochondral scaffold was CAD designed. A prototype of the resulting subchondral bone scaffold was constructed by stereolithography using resin.

Results

Micro-CT revealed that subchondral bone presented a gradually changing structure from the subchondral to spongy bone tissue. The subchondral bone plate was more compact with ~20 % porosity compared with ~60 % porosity for the spongy bone. Histology and SEM showed that cartilage was stabilized on the subchondral bone plate by conjunctions, imbedding, interlocking, and binding forces generated by collagen fibers. Some scattered defects allow blood vessel invasion and nutritional supply.

Conclusions

The subchondral bone plate is not an intact plate between the cartilage and bone cavity, and some scattered defects exist that allow blood vessel invasion and nutritional supply. This characteristic was used to design an osteochondral scaffold. This could be used to construct an osteochondral complex that is similar to native bones.

Poor osteochondral repair by a biomimetic collagen scaffold: 1- to 3-year clinical and radiological follow-up

INTRODUCTION

Treatment of osteochondral injuries is challenging, and no gold standard has been established. Layered cell-free scaffolds are a new treatment option for these defects. The aim of this study was to evaluate the osteochondral repair in patients treated with the MaioRegen(®) scaffold, a cell-free biomimetic scaffold consisting of type I collagen and hydroxyapatite. Treatment using this scaffold has previously shown promising clinical results.

METHODS

Ten patients with osteochondral lesions in the knee (n = 6) or in the talus (n = 4) were enrolled. The patients underwent pre-operative MRI and CT scans and were assessed at 1- and 2.5-year timescales post-operatively. The cartilage and bone formations were evaluated semi-quantitatively using the MOCART score. Knee patients were clinically evaluated using KOOS, subjective IKDC and Tegner scores, whereas ankle patients were evaluated using AOFAS Hindfoot and Tegner scores.

RESULTS

Two patients were re-operated and excluded from further follow-up due to treatment failure. None of the patients had complete regeneration of the subchondral bone evaluated using CT. At 2.5 years, 6/8 patients had no or very limited (<10 %) bone formation in the defects and 2/8 had 50-75 % bone formation in the treated defect. MRI showed no improvement in the MOCART score at any time point. The IKDC score improved from 41.3 to 80.7, and the KOOS pain subscale improved from 63.8 to 90.8 at 2.5-year follow-up. No improvement was found with the remaining KOOS subscales, the Tegner or AOFAS Ankle-Hindfoot score.

CONCLUSION

Treatment of osteochondral defects in the ankle and knee joint with a biomimetic scaffold resulted in incomplete cartilage repair and poor subchondral bone repair at 1- and 2.5-year follow-up. Clinical significant improvements were observed. These results raise serious concerns about the biological repair potential of the MaioRegen(®) scaffold, and we advise to use the MaioRegen(®) scaffold with caution.

LEVEL OF EVIDENCE

Prospective therapeutic study, Level IV.

Chemical and morphological gradient scaffolds to mimic hierarchically complex tissues: From theoretical modeling to their fabrication

Porous multiphase scaffolds have been proposed in different tissue engineering applications because of their potential to artificially recreate the heterogeneous structure of hierarchically complex tissues. Recently, graded scaffolds have been also realized, offering a continuum at the interface among different phases for an enhanced structural stability of the scaffold. However, their internal architecture is often obtained empirically and the architectural parameters rarely predetermined. The aim of this work is to offer a theoretical model as tool for the design and fabrication of functional and structural complex graded scaffolds with predicted morphological and chemical features, to overcome the time-consuming trial and error experimental method. This developed mathematical model uses laws of motions, Stokes equations, and viscosity laws to describe the dependence between centrifugation speed and fiber/particles sedimentation velocity over time, which finally affects the fiber packing, and thus the total porosity of the 3D scaffolds. The efficacy of the theoretical model was tested by realizing engineered graded grafts for osteochondral tissue engineering applications. The procedure, based on combined centrifugation and freeze-drying technique, was applied on both polycaprolactone (PCL) and collagen-type-I (COL) to test the versatility of the entire process. A functional gradient was combined to the morphological one by adding hydroxyapatite (HA) powders, to mimic the bone mineral phase. Results show that 3D bioactive morphologically and chemically graded grafts can be properly designed and realized in agreement with the theoretical model. Biotechnol. Bioeng. 2016;113: 2286-2297. © 2016 Wiley Periodicals, Inc.

Cartilage tissue engineering: From biomaterials and stem cells to osteoarthritis treatments

Articular cartilage is a non-vascularized and poorly cellularized connective tissue that is frequently damaged as a result of trauma and degenerative joint diseases such as osteoarthrtis. Because of the absence of vascularization, articular cartilage has low capacity for spontaneous repair. Today, and despite a large number of preclinical data, no therapy capable of restoring the healthy structure and function of damaged articular cartilage is clinically available. Tissue-engineering strategies involving the combination of cells, scaffolding biomaterials and bioactive agents have been of interest notably for the repair of damaged articular cartilage. During the last 30 years, cartilage tissue engineering has evolved from the treatment of focal lesions of articular cartilage to the development of strategies targeting the osteoarthritis process. In this review, we focus on the different aspects of tissue engineering applied to cartilage engineering. We first discuss cells, biomaterials and biological or environmental factors instrumental to the development of cartilage tissue engineering, then review the potential development of cartilage engineering strategies targeting new emerging pathogenic mechanisms of osteoarthritis.

Surgical treatment of early knee osteoarthritis with a cell-free osteochondral scaffold: results at 24 months of follow-up

PURPOSE

"Early Osteoarthritis (EOA)" has been defined combining clinical, imaging and surgical parameters, with the aim to identify patients in early degenerative phases, who might benefit from the use of available regenerative procedures. Aim of this first clinical trial is to prospectively evaluate the results obtained in a group of patients meeting the inclusion criteria of "EOA" as proposed by the ESSKA Cartilage Committee, and surgically treated with the implantation of a multi-phasic osteochondral scaffold.

METHODS

23 patients were prospectively evaluated at 12 and 24 months of follow-up. Etiology of the chondral or osteochondral defect was rated as microtraumatic or degenerative in 18 cases, and traumatic in 5 cases. Patients included were complaining of clinical symptoms like knee pain and affected by chondral and osteochondral lesions located at the femoral condyles or trochlea and MRI findings demonstrating articular cartilage degeneration and/or meniscal degeneration and/or subchondral bone marrow lesions.

RESULTS

All patients increased significantly in any clinical score adopted. The IKDC subjective score increased from 42.8 ± 13.8 at basal evaluation to 74.3 ± 17.4 at 12 months' (p < 0.0005), being stable (74.9 ± 20.4) up to the final follow-up of 24 months. Tegner score showed a statistically significant improvement in sports activity from 3.3 ± 2.7 pre-operative to 4.6 ± 2.2 at 12 months (p < 0.005), with a slight improvement to the final evaluation (4.7 ± 2.1; n.s.). However, the activity level was significantly lower than the pre-injury one (6.1 ± 2.6; p = 0.004). A significant difference was shown between patients younger versus older than 40 years, with younger patients had better clinical improvement (76.0 ± 18.6 vs 45.1 ± 38.8 respectively, p = 0.037).

CONCLUSIONS

The implantation of a multi-phasic osteochondral scaffold represents a good option after failure of conservative management for Early OA patients, where younger age represent an important factor for a better outcome. Longer follow-up is needed to evaluate the benefit over time.

LEVEL OF EVIDENCE

IV, case series.

Biomimetic biphasic scaffolds for osteochondral defect repair

The osteochondral defects caused by vigorous trauma or physical disease are difficult to be managed. Tissue engineering provides a possible option to regenerate the damaged osteochondral tissues. For osteochondral reconstruction, one intact scaffold should be considered to support the regeneration of both cartilage and subchondral bone. Therefore, the biphasic scaffolds with the mimic structures of osteochondral tissues have been developed to close this chasm. A variety of biomimetic bilayer scaffolds fabricated from natural or synthetic polymers, or the ones loading with growth factors, cells, or both of them make great progresses in osteochondral defect repair. In this review, the preparation and in vitro and/or in vivo verification of bioinspired biphasic scaffolds are summarized and discussed, as well as the prospect is predicted.

Adipose-Derived Mesenchymal Stem Cells for the Treatment of Articular Cartilage: A Systematic Review on Preclinical and Clinical Evidence

Among the current therapeutic approaches for the regeneration of damaged articular cartilage, none has yet proven to offer results comparable to those of native hyaline cartilage. Recently, it has been claimed that the use of mesenchymal stem cells (MSCs) provides greater regenerative potential than differentiated cells, such as chondrocytes. Among the different kinds of MSCs available, adipose-derived mesenchymal stem cells (ADSCs) are emerging due to their abundancy and easiness to harvest. However, their mechanism of action and potential for cartilage regeneration are still under investigation, and many other aspects still need to be clarified. The aim of this systematic review is to give an overview of in vivo studies dealing with ADSCs, by summarizing the main evidence for the treatment of cartilage disease of the knee.

Meniscal Scaffolds - Preclinical Evidence to Support their Use: A Systematic Review

Arthroscopic meniscal treatment is the most common procedure performed in the orthopedic practice. Current management of meniscal pathology relies on different therapeutic options, ranging from selective meniscectomy, suturing, and to meniscal replacement by using either allografts or scaffolds. The progresses made in the field of regenerative medicine and biomaterials allowed to develop several meniscal substitutes, some of those currently used in the clinical practice. Before reaching the clinical application, these devices necessarily undergo accurate testing in the animal model: the aim of the present manuscript is to systematically review the scientific evidence derived by animal model results for the use of meniscal scaffolds, in order to understand the current state of research in this particular field and to identify the trends at preclinical level that may influence in the near future the clinical practice. Thirty-four papers were included in the present analysis. In 12 cases the meniscal scaffolds were used with cells to further stimulate tissue regeneration. With the exception of some negative reports regarding dacron-based scaffolds, the majority of the trials highlighted that biomaterials and bio-engineered scaffolds are safe and could play a beneficial role in stimulating meniscal healing and in chondral protection. With regard to the benefits of cell augmentation, the evidence is limited to a small number of studies and no conclusive evidence is available. However, preclinical evidence seems to suggest that cells could enhance tissue regeneration with respect to the use of biomaterials alone, and further research should confirm the translational potential of cell-based approach.

Scaffold-based cartilage treatments: with or without cells? A systematic review of preclinical and clinical evidence

PURPOSE

Regenerative scaffold-based procedures are emerging as a potential therapeutic option for the treatment of chondral and osteochondral lesions. In general, we can summarize most of the recent developments to reach clinical application into 2 major trends: the use of different cell sources or the application of biomaterials as a cell-free approach. The aim of this systematic review was to analyze both preclinical and clinical studies on these new trends to understand how the available evidence supports the use of cell sources or justifies the cell-free approach for the scaffold-based treatment of cartilage lesions.

METHODS

The research was performed using the PubMed database by looking at studies published in the English language referring to chondral or osteochondral defect repair with scaffold-based procedures until the end of 2013. The following strings were used: ("cartilage"[MeSH] AND "tissue scaffolds"[MeSH]).

RESULTS

The search showed an increasing number of published articles each year for both scaffold-based approaches, identifying a total of 305 articles. Among clinical trials, 116 used cell-based scaffold treatments and 11 used scaffolds alone. In the preclinical setting, a scaffold/cell combination was the most used treatment approach (133 v 45 articles), with mesenchymal stem cells (MSCs) being the favorite cell type. Bone marrow was the most used cell source, but other sources are gaining interest. Among articles comparing scaffolds with or without cells, the majority reported superior results for cells (71 of 89 articles). In the clinical setting, most of the articles analyzed chondrocyte-based scaffolds, with only 7 studies using MSCs; all cells were from bone marrow. Despite the lower number of articles, cell-free scaffolds are gaining popularity, with a recent increase in published studies showing promising results.

CONCLUSIONS

This systematic review underlined the difficulties in understanding the real need for cells to increase the scaffold-based cartilage healing potential because of the heterogeneity of products used as well as the design of the published studies. Scaffold and cell combinations were the most investigated option in the preclinical setting, showing generally superior results, but in the clinical setting, both strategies remain used. In particular, although chondrocytes are the most commonly used cell type, research showed increasing interest in the potential of MSCs for cartilage regeneration. However, the difficulties in managing cell cultures, together with the development of a new generation of materials able to exploit the intrinsic tissue regeneration ability, justifies the clinical use of cell-free scaffolds, with increasing literature and promising preliminary results.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I to IV studies.

A new injectable biphasic hydrogel based on partially hydrolyzed polyacrylamide and nanohydroxyapatite as scaffold for osteochondral regeneration

Fabrication of an injectable biphasic hydrogel based on partially hydrolyzed polyacrylamide (HPAM), nanocrystalline hydroxyapatite (nHAp), and chromium acetate (Cr(iii)) as a novel scaffold for osteochondral repair has been attempted.

Tibial plateau lesions. Surface reconstruction with a biomimetic osteochondral scaffold: Results at 2 years of follow-up

INTRODUCTION

Tibial plateau articular pathology caused by post-traumatic or degenerative lesions is a challenge for the orthopaedic surgeon and can lead to early osteoarthritis. The aim of the present study was to evaluate the results of treatment of these complex defects with implantation of an osteochondral scaffold, which is designed to target the cartilage surface and to reconstruct joint anatomy by addressing the entire osteochondral unit.

MATERIALS AND METHODS

Eleven patients (5 female and 6 male) with a mean age of 37.3 ± 11.0 years and osteochondral lesions of the tibial plateau (mean 5.1 ± 2.7 cm(2); range 3.0-12.5 cm(2)) were treated with the implantation of an osteochondral biomimetic collagen-hydroxyapatite scaffold (Maioregen(®), Fin-Ceramica, Faenza, Italy). Comorbidities were addressed taking care to restore the correct limb alignment. Patients were evaluated pre-operatively and prospectively followed-up for 2 years using the International Knee Documentation Committee (IKDC) subjective and objective scores; activity level was documented using the Tegner score.

RESULTS

Three patients experienced minor adverse events. No patients required further surgery for treatment failure during the study follow-up period, and 8 patients (72.7%) reported a marked improvement. The IKDC subjective score improved from 42.5 ± 10.2 before treatment to 69.8 ± 19.0 at 12 months (p<0.05), with stable results at 24 months. The IKDC objective score increased from 27.3% normal and nearly normal knees before treatment to 85.7% normal and nearly normal knees at 24 months of follow-up. The Tegner score increased from 2.3 ± 2.1 before treatment to 4.8 ± 2.4 at 12 months (p<0.05), and was stable at the final follow-up.

CONCLUSION

The present study on the implantation of an osteochondral scaffold for the treatment of tibial plateau lesions showed a promising clinical outcome at short-term follow-up, which indicates that this procedure can be considered as a possible treatment option, even in these complex defects, when comorbidities are concomitantly addressed.

Osteochondral repair by a novel interconnecting collagen-hydroxyapatite substitute: a large-animal study

A novel three-dimensional bicomponent substitute made of collagen type I and hydroxyapatite was tested for the repair of osteochondral lesions in a swine model. This scaffold was assembled by a newly developed method that guarantees the strict integration between the organic and the inorganic parts, mimicking the biological tissue between the chondral and the osseous phase. Thirty-six osteochondral lesions were created in the trochlea of six pigs; in each pig, two lesions were treated with scaffolds seeded with autologous chondrocytes (cell+group), two lesions were treated with unseeded scaffolds (cell- group), and the two remaining lesions were left untreated (untreated group). After 3 months, the animals were sacrificed and the newly formed tissue was analyzed to evaluate the degree of maturation. The International Cartilage Repair Society (ICRS) macroscopic assessment showed significantly higher scores in the cell- and untreated groups when compared with the cell+ group. Histological evaluation showed the presence of repaired tissue, with fibroblast-like and hyaline-like areas in all groups; however, with respect to the other groups, the cell- group showed significantly higher values in the ICRS II histological scores for "cell morphology" and for the "surface/superficial assessment." While the scaffold seeded with autologous chondrocytes promoted the formation of a reparative tissue with high cellularity but low glycosaminoglycans (GAG) production, on the contrary, the reparative tissue observed with the unseeded scaffold presented lower cellularity but higher and uniform GAG distribution. Finally, in the lesions treated with scaffolds, the immunohistochemical analysis showed the presence of collagen type II in the peripheral part of the defect, indicating tissue maturation due to the migration of local cells from the surroundings. This study showed that the novel osteochondral scaffold was easy to handle for surgical implantation and was stable within the site of lesion; at the end of the experimental time, all implants were well integrated with the surrounding tissue and no signs of synovitis were observed. The quality of the reparative tissue seemed to be superior for the lesions treated with the unseeded scaffolds, indicating the promising potential of this novel biomaterial for use in a one-stage procedure for osteochondral repair.

A one-step treatment for chondral and osteochondral knee defects: clinical results of a biomimetic scaffold implantation at 2 years of follow-up

The increasing interest in the role of subchondral bone with regard to articular surface disease led to the development of new bioengineered strategies. Aim of this study is to evaluate the clinical and MRI outcome after the implantation of a nanostructured biomimetic three-phasic collagen-hydroxyapatite construct for the treatment of chondral and osteochondral defects of the knee in a large cohort of patients. Seventy-nine patients (63 M, 16 W), affected by grade III-IV femoral condyle or trochlea chondral lesions or osteochondritis dissecans (OCD) were consecutively treated. Mean age was 31.0 ± 11.3 years, mean lesion size was 3.2 ± 2.0 cm(2). Fifty patients underwent previous surgeries, concurrent procedures were necessary in 39 cases. The clinical outcome was evaluated using the IKDC and Tegner scores at 12 and 24 months of follow-up. At follow-up times an MRI was performed and evaluated with the MOCART score. All the scores improved significantly from the baseline. IKDC subjective score showed a further increase between 12 and 24 months of follow-up, and 82.2% of the patients improved their symptoms at the final evaluation. Patients affected by OCDs had better results than those with degenerative lesions. Some abnormal MRI findings were present, even though no correlation was found with the clinical outcome. This one-step biomimetic approach developed to favor osteochondral tissue regeneration is effective in treating knees affected by damages of the articular surface, leading to a significant clinical improvement. However, abnormal MRI findings were present, even if not correlated with the clinical outcome.

Single-plug autologous osteochondral transplantation: results at minimum 16 years' follow-up

Different techniques have been proposed for the treatment of cartilage defects. Among the currently available options, autologous single-plug osteochondral transplantation is one of the few to be applied to address small and medium lesions. The goal of the current study was to document the long-term clinical outcome of a cohort of patients treated by this surgical strategy, which consists of harvesting a single osteochondral plug from a less weight bearing area of the knee and implanting it on the defect site by press-fit technique. Fifteen patients were enrolled. Age at surgery was 30.2±15.3 years, and body mass index was 22.5±3.0 kg/m(2). The inclusion criteria were clinical symptoms, such as knee pain or swelling, and grade III to IV chondral and osteochondral knee lesions. Patients were prospectively evaluated up to a mean of 17.5±3.5 years of follow-up by using Lysholm, International Knee Documentation Committee (IKDC) subjective, and Tegner scores. A significant improvement was noted in all clinical scores. In particular, the IKDC subjective score increased from 34.5±23.6 to 66.3±26.4 (P=.001). The Lysholm score showed a similar trend. From a baseline value of 47.8±29.5, the score increased to 79.8±24.6 at the last evaluation (P=.001). A significant increase in Tegner score was observed at the 2-year evaluation, with stable results up to the last follow-up. Four failures were reported, which in 3 cases occurred at mid- to long-term follow-up, confirming that this technique can be considered a suitable option for the treatment of small and medium chondral and osteochondral lesions in young patients.

Clinical results of multilayered biomaterials for osteochondral regeneration

Several techniques have been used during the years to treat chondral and osteochondral lesions. Among them, the emerging trend in the field of osteochondral regeneration is to treat the entire osteochondral unit by implanting cell-free scaffolds, which provide a three-dimensional support for the cell growth and may act themselves as stimuli for an "in situ" tissue regeneration. Various multi-layered products have been proposed that mimic both the subchondral bone and the cartilaginous layer. Among these, three have currently been reported in the literature. One has been widely investigated: it is a nanocomposite three-layered collagen-hydroxyapatite scaffold, which is showing promising results clinically and by MRI even at mid-term follow-up. The second is a PLGA-calcium-sulfate bilayer scaffold: however, the literature findings are still controversial and only short-term outcomes of limited case-series have been published. The most recent one is a solid aragonite-based scaffold, which seems to give promising clinical and MRI outcomes, even if the literature is still lacking more in-depth evaluations.Even though the Literature related to this topic is quickly increasing in number, the clinical evidence it is still limited to some case series, and high-level studies are needed to better demonstrate their real effectiveness.

Treatment of Large Knee Osteochondral Lesions With a Biomimetic Scaffold: Results of a Multicenter Study of 49 Patients at 2-Year Follow-up

BACKGROUND

Osteochondral knee lesions represent a challenging condition encountered by orthopaedic surgeons. A variety of methods have been developed to repair articular cartilage defects. However, these techniques are limited by donor site morbidity or by the requirement for a staged procedure.

PURPOSE

To assess the effectiveness of a biomimetic osteochondral scaffold for the treatment of large osteochondral knee lesions.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

From 2009 to 2011, a total of 49 patients affected by isolated large osteochondral knee lesions (mean [± SD] size, 4.35 ± 1.26 cm2) were treated with the biomimetic scaffold. Patients were evaluated using the International Knee Documentation Committee (IKDC), Tegner, and visual analog scale (VAS) pain scores, as well as magnetic resonance imaging (MRI) up to 3-year follow-up. The MOCART (magnetic resonance observation of cartilage repair tissue) score was performed to analyze different variables. Biopsies were carried out in 5 patients. Four of the 5 second-look arthroscopies and biopsies were performed on patients with failed results because of ethical issues.

RESULTS

The mean IKDC subjective score increased significantly from 45.45 ± 19.29 preoperatively to 70.86 ± 18.08 at 1-year follow-up and to 75.42 ± 19.31 at 2-year follow-up (P < .001). The IKDC objective score changed from 50% normal and nearly normal knees before treatment to 89.79% at the 2-year follow-up. There was a statistically significant improvement (P < .005) in VAS score from the preoperative level (6.69 ± 1.88) to the 2-year follow-up (1.96 ± 2.47). Tegner scores increased (P < .001) from the preoperative value (2.20 ± 0.67) to the 2-year follow-up (4.9 ± 1.73) without achieving preinjury level. A correlation was found between the IKDC subjective score and age (P < .001, r = -0.497, ρ = -0.502). Patients affected by osteochondritis dissecans (OCD) achieved a statistically significantly better outcome (P < .05). A subgroup of 19 competitive athletes showed a statistically significantly improvement (P < .001) in the subjective IKDC (86.5 ± 13.2) compared with the nonathletic subpopulation (69.03 ± 19.41) at the 2-year follow-up. The MRI findings of 30 patients were available at 2-year follow-up: 70% showed complete filling of the lesion, 63.3% had an intact articular surface, and 86% had mild or no effusion. In all cases, in dual T2-weighted fast spin echo sequence, the repair tissue showed a hyperintensive signal with respect to the surrounding subchondral bone; however, no edema was observed.

CONCLUSION

The study findings indicate that the biomimetic scaffold that was investigated is an off-the-shelf, cell-free, and cost-effective implant that can regenerate either cartilage or subchondral bone. The scaffold allows a 1-step surgical procedure that can be used for osteochondral lesions, OCD, and in some cases osteonecrosis.

Fibrin glue improves osteochondral scaffold fixation: study on the human cadaveric knee exposed to continuous passive motion

OBJECTIVE

To evaluate stability and integrity of bi-layer and three-layer collagen-hydroxyapatite (C-HA) osteochondral scaffolds in a human cadaveric knee exposed to continuous passive motion (CPM) with and without loading and the role of added fibrin glue to improve the press-fit fixation of C-HA scaffolds.

DESIGN

Osteochondral lesions (2.0 × 1.5 cm) were chiseled out on both condyles and trochlea in eight human cadaveric knees. A total of 24 bi-layer (5 mm, four in each condyle) or three-layer C-HA scaffolds (8 mm, eight in the trochlea, four in each condyle) were first press-fit implanted and underwent testing with CPM, 90 cycles, 0°-90°. The second set of 24 scaffolds was implanted in cleaned lesions with the addition of fibrin glue. Two knees with fibrin glue fixation were additionally exposed to 15 kg loading, with 30 cycles of CPM, 0°-30°. Then, the knees were reopened and the scaffolds were evaluated using semi-quantitative Drobnic and modified Bekkers scores.

RESULTS

All but two scaffolds remained in the lesions site throughout CPM. Two implants failed: both were bi-layer osteochondral scaffolds, press-fit implanted at the lateral femoral condyle (LFC). A statistically significant difference was obtained between press-fit and fibrin glue implants with both Drobnic (2.9 ± 0.7 vs 4.3 ± 0.1, P < 0.0005) and Bekkers (3.3 ± 1.0 vs 5.0 ± 0.1, P < 0.0005) scores. Additional knee loading did not affect fibrin glue scaffold fixation or integrity.

CONCLUSION

This cadaveric study showed fibrin glue notably improved bi-layer or three-layer C-HA scaffold press-fit fixation regardless of lesion location. It is therefore recommended that fibrin glue be used during surgery to improve early post-operative C-HA scaffold stability and integrity.

Mesenchymal stem cells in the treatment of traumatic articular cartilage defects: a comprehensive review

Articular cartilage has a limited capacity to repair following injury. Early intervention is required to prevent progression of focal traumatic chondral and osteochondral defects to advanced cartilage degeneration and osteoarthritis. Novel cell-based tissue engineering techniques have been proposed with the goal of resurfacing defects with bioengineered tissue that recapitulates the properties of hyaline cartilage and integrates into native tissue. Transplantation of mesenchymal stem cells (MSCs) is a promising strategy given the high proliferative capacity of MSCs and their potential to differentiate into cartilage-producing cells - chondrocytes. MSCs are historically harvested through bone marrow aspiration, which does not require invasive surgical intervention or cartilage extraction from other sites as required by other cell-based strategies. Biomaterial matrices are commonly used in conjunction with MSCs to aid cell delivery and support chondrogenic differentiation, functional extracellular matrix formation and three-dimensional tissue development. A number of specific transplantation protocols have successfully resurfaced articular cartilage in animals and humans to date. In the clinical literature, MSC-seeded scaffolds have filled a majority of defects with integrated hyaline-like cartilage repair tissue based on arthroscopic, histologic and imaging assessment. Positive functional outcomes have been reported at 12 to 48 months post-implantation, but future work is required to assess long-term outcomes with respect to other treatment modalities. Despite relatively positive outcomes, further investigation is required to establish a consensus on techniques for treatment of chondral and osteochondral defects with respect to cell source, isolation and expansion, implantation density, in vitro precultivation, and scaffold composition. This will allow for further optimization of MSC proliferation, chondrogenic differentiation, bioengineered cartilage integration, and clinical outcome.