Clinical outcome of autologous chondrocyte implantation at 5 years in US subjects

Boosting chondrocyte bioactivity with ultra-sulfated glycopeptide supramolecular polymers

Although autologous chondrocyte transplantation can be effective in articular cartilage repair, negative side effects limit the utility of the treatment, such as long recovery times, poor engraftment or chondrogenic dedifferentiation, and cell leakage. Peptide-based supramolecular polymers have emerged as promising bioactive systems to promote tissue regeneration through cell signaling and dynamic behavior. We report here on the development of a series of glycopeptide amphiphile supramolecular nanofibers with chondrogenic bioactivity. These supramolecular polymers were found to have the ability to boost TGFβ-1 signaling by displaying galactosamine moieties with differing degrees of sulfation on their surfaces. We were also able to encapsulate chondrocytes with these nanostructures as single cells without affecting viability and proliferation. Among the monomers tested, assemblies of trisulfated glycopeptides led to elevated expression of chondrogenic markers relative to those with lower degrees of sulfation that mimic chondroitin sulfate repeating units. We hypothesize the enhanced bioactivity is rooted in specific interactions of the supramolecular assemblies with TGFβ-1 and its consequence on cell signaling, which may involve elevated levels of supramolecular motion as a result of high charge in trisulfated glycopeptide amphiphiles. Our findings suggest that supramolecular polymers formed by the ultra-sulfated glycopeptide amphiphiles could provide better outcomes in chondrocyte transplantation therapies for cartilage regeneration. STATEMENT OF SIGNIFICANCE: This study prepares glycopeptide amphiphiles conjugated at their termini with chondroitin sulfate mimetic residues with varying degrees of sulfation that self-assemble into supramolecular nanofibers in aqueous solution. These supramolecular polymers encapsulate chondrocytes as single cells through intimate contact with cell surface structures, forming artificial matrix that can localize the growth factor TGFβ-1 in the intercellular environment. A high degree of sulfation on the glycopeptide amphiphile is found to be critical in elevating chondrogenic cellular responses that supersede the efficacy of natural chondroitin sulfate. This work demonstrates that supramolecular assembly of a unique molecular structure designed to mimic chondroitin sulfate successfully boosts chondrocyte bioactivity by single cell encapsulation, suggesting a new avenue implementing chondrocyte transplantation with supramolecular nanomaterials for cartilage regeneration.

Prognostic factors for the management of chondral defects of the knee and ankle joint: a systematic review

Purpose

Different surgical techniques to manage cartilage defects are available, including microfracture (MFx), autologous chondrocyte implantation (ACI), osteoarticular auto- or allograft transplantation (OAT), autologous matrix-induced chondrogenesis (AMIC). This study investigated the patient-related prognostic factors on the clinical outcomes of surgically treated knee and ankle cartilage defects.

Methods

This study followed the PRISMA statement. In May 2022, the following databases were accessed: PubMed, Google Scholar, Embase, and Scopus. All the studies investigating the outcomes of surgical management for knee and/or talus chondral defects were accessed. Only studies performing mesenchymal stem cells transplantation, OAT, MFx, ACI, and AMIC were considered. A multiple linear model regression analysis through the Pearson Product–Moment Correlation Coefficient was used.

Results

Data from 184 articles (8905 procedures) were retrieved. Female sex showed a positive moderate association with visual analogue scale at last follow-up (P = 0.02). Patient age had a negative association with the American Orthopaedic Foot and Ankle Score (P = 0.04) and Lysholm Knee Scoring Scale (P = 0.03). BMI was strongly associated with graft hypertrophy (P = 0.01). Greater values of VAS at baseline negatively correlate with lower values of Tegner Activity Scale at last follow-up (P < 0.0001).

Conclusion

The clinical outcomes were mostly related to the patients’ performance status prior surgery. A greater BMI was associated with greater rate of hypertrophy. Female sex and older age evidenced fair influence, while symptom duration prior to the surgical intervention and cartilage defect size evidenced no association with the surgical outcome. Lesion size and symptom duration did not evidence any association with the surgical outcome.

Synthesis of degradable double network gels using a hydrolysable cross-linker

Double network (DN) gels have remarkably high mechanical strength and toughness and can be potentially applied in biomedical applications such as cartilage regeneration. However, most DN gels synthesised by usual...

3D MRI of Articular Cartilage

Osteoarthritis, characterized by the breakdown of articular cartilage and other joint structures, is one of the most prevalent and disabling chronic diseases in the United States. Magnetic resonance imaging is a commonly used imaging modality to evaluate patients with joint pain. Both two-dimensional fast spin-echo sequences (2D-FSE) and three-dimensional (3D) sequences are used in clinical practice to evaluate articular cartilage. The 3D sequences have many advantages compared with 2D-FSE sequences, such as their high in-plane spatial resolution, thin continuous slices that reduce the effects of partial volume averaging, and ability to create multiplanar reformat images following a single acquisition. This article reviews the different 3D imaging techniques available for evaluating cartilage morphology, illustrates the strengths and weaknesses of 3D approaches compared with 2D-FSE approaches for cartilage imaging, and summarizes the diagnostic performance of 2D-FSE and 3D sequences for detecting cartilage lesions within the knee and hip joints.

A Collagen-Mimetic Organic-Inorganic Hydrogel for Cartilage Engineering

Promising strategies for cartilage regeneration rely on the encapsulation of mesenchymal stromal cells (MSCs) in a hydrogel followed by an injection into the injured joint. Preclinical and clinical data using MSCs embedded in a collagen gel have demonstrated improvements in patients with focal lesions and osteoarthritis. However, an improvement is often observed in the short or medium term due to the loss of the chondrocyte capacity to produce the correct extracellular matrix and to respond to mechanical stimulation. Developing novel biomimetic materials with better chondroconductive and mechanical properties is still a challenge for cartilage engineering. Herein, we have designed a biomimetic chemical hydrogel based on silylated collagen-mimetic synthetic peptides having the ability to encapsulate MSCs using a biorthogonal sol-gel cross-linking reaction. By tuning the hydrogel composition using both mono- and bi-functional peptides, we succeeded in improving its mechanical properties, yielding a more elastic scaffold and achieving the survival of embedded MSCs for 21 days as well as the up-regulation of chondrocyte markers. This biomimetic long-standing hybrid hydrogel is of interest as a synthetic and modular scaffold for cartilage tissue engineering.

The partial femoral condyle focal resurfacing (HemiCAP-UniCAP) for treatment of full-thickness cartilage defects, systematic review and meta-analysis

Knee osteochondral defects are a common problem among people, especially young and active patients. So effective joint preserving surgeries is essential to prevent or even delay the onset of osteoarthritis for these group of patients. This study aims to critically appraise and evaluate the evidence for the results and effectiveness of femoral condyle resurfacing (HemiCAP/ UniCAP) in treatment of patients with focal femoral condyle cartilage defect. Using the search terms : HemiCAP, UniCAP, Episurf, focal, femoral, condyle, inlay and resur-facing, we reviewed the PubMed and EMBASE and the Cochrane Database of Systematic Reviews (CDSR) to find any articles published up to March 2020. The short term follow-up of the HemiCAP shows (6.74 %) revision rate. However, 29.13 % loss of follow up let us consider these results with caution especially if the revision rate progressively increased with time to 19.3 % in 5-7 years with no enough evidence for the long term results except the data from the Australian Joint Registry 2018, where the cumulative revision rate was 40.6 % (33.5, 48.4) at ten years. The UniCAP that used for defect more than 4 cm 2 has a high revision rate (53.66 %) which is considered unacceptable revision rate in com-parison to another similar prosthesis such as Uni-Knee Arthroplasty (UKA). The evidence from published studies and our meta- analysis suggests that partial resurfacing of the femoral condyle (HemiCAP) doesn’t support its usage as a tool to treat the focal cartilage defect in middle- aged patients. The UniCAP as femoral condyle resurfacing has very high revision rate at 5-7 years (53.66 %) which make us recommend against its usage.

The effect of different cross-linking conditions of EDC/NHS on type II collagen scaffolds: an in vitro evaluation

The purpose of this paper is to analyze the properties of porcine cartilage type II collagen scaffolds crosslinked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxy-succinamide (EDC/NHS) under different conditions. The porous EDC/NHS-crosslinked scaffolds were obtained through a two-step freeze-drying process. To determine the optimal crosslinking condition, we used different solvents and various crosslinking temperatures to prepare the scaffolds. Three crosslinking solutions were prepared with different solvents, photographs were taken with a flash in the darkroom, and light transmission was observed. Type II collagen was crosslinked on a horizontal shaker at a speed of 60 r/min according to the above grouping conditions, and then the structural change of the scaffold in each group was observed. To investigate the swelling ratio and the in vitro degradation of the collagen scaffold, tests were also carried out by immersion of the scaffolds in a PBS solution and digestion in type II collagenase, respectively. The influence of the scaffolds on the proliferation of chondrocytes was assessed by the methyl thiazolyl tetrazolium colorimetric assay. The morphology of the crosslinked scaffolds cocultured with chondrocytes was characterized by a scanning electron microscope. The results proved that 75% alcohol and a crosslinking temperature of 37 °C are recommended. Collagen fibrils are more densely packed after crosslinking with EDC/NHS and have a more uniform structure than that of noncrosslinked ones. The EDC-crosslinked scaffolds possessed excellent mechanical property and biocompatibility.

Autologous Chondrocyte Implantation "Segmental-Sandwich" Technique for Deep Osteochondral Defects in the Knee: Clinical Outcomes and Correlation With Magnetic Resonance Imaging Findings

Background

Symptomatic osteochondral defects are difficult to manage, especially in patients with deep (>8-10 mm) empty defects. The restoration of articular congruence is crucial to avoid the progression to osteoarthritis (OA).

Purpose

To describe the autologous chondrocyte implantation (ACI) "segmental-sandwich" technique for restoration of the osteochondral unit and to evaluate midterm outcomes in patients treated with this procedure. Correlations between magnetic resonance imaging (MRI) and radiographic findings with outcomes were assessed.

Study Design

Case series; Level of evidence, 4.

Methods

Outcomes were evaluated for a consecutive cohort of 15 patients with symptomatic deep (>8 mm) osteochondral lesions who underwent autologous bone grafting plus the ACI segmental-sandwich technique performed by a single surgeon between 2003 and 2011. Patients with a minimum 2-year follow-up were included. All patients completed validated clinical outcome scales and a patient satisfaction survey. The Kellgren-Lawrence (K-L) grade was assessed for the progression to OA. The repair site was evaluated with the MOCART (magnetic resonance observation of cartilage repair tissue) score. Filling and tissue characteristics of the bone defect were analyzed with MRI.

Results

All patients (mean age at surgery, 31.0 ± 9.1 years) were available for follow-up (mean follow-up, 7.8 ± 3.0 years; range, 2-15 years). The mean chondral lesion size was 6.0 ± 3.5 cm² (range, 1.5-13.5 cm²), with a mean bone defect area of 1.7 cm² (27%-40% of overall surface area treated by ACI) and depth of 1.0 cm. All patients had successful clinical outcomes, and all functional scores improved significantly (P < .05). Patients reported a very high satisfaction rate (93%). The K-L grade demonstrated no significant progression to OA over a mean follow-up of 4.7 years. For 12 patients with MRI results available, the mean MOCART score at a mean of 3.3 years was 64.2 ± 19.9, with complete or near-complete (≥75% of defect volume) chondral defect filling (83%) and complete integration to adjacent cartilage (83%). Bone defects were completely filled in 83% of patients.

Conclusion

The ACI segmental-sandwich technique provides significant functional improvements at midterm follow-up and excellent survival rates. This unique treatment allows for the resurfacing of cartilage defects and the repair of underlying segmental bone lesions.

Injectable amine functionalized graphene and chondroitin sulfate hydrogel with potential for cartilage regeneration

Damaged cartilage does not readily heal and often requires surgical intervention that only modestly improves outcomes. A synthetic material that could be injected and covalently crosslinked in situ to form a bioactive, mechanically robust scaffold that promotes stem cell chondrogenic differentiation holds promise for next-generation treatment of cartilage lesions. Here, Johnson-Claisen rearrangement chemistry was performed on graphene oxide (GO) to enable functionalization with a primary amine covalently bound to the graphenic backbone through a chemically stable linker. The primary amines are used to form covalent crosslinks with chondroitin sulfate, an important component of cartilage that promotes regeneration, to form a hydrogel (EDAG-CS). The EDAG-CS system gels in situ within 10 min, and the graphenic component imparts improved mechanical properties, including stiffness (320% increase) and toughness (70% increase). EDAG-CS hydrogels are highly porous, resistant to degradation, and enable the growth of human mesenchymal stem cells and their deposition of collagen matrix. This system has potential to improve clinical outcomes of patients with cartilage damage.

Autologous Chondrocyte Implantation for Bipolar Chondral Lesions in the Patellofemoral Compartment: Clinical Outcomes at a Mean 9 Years' Follow-up

BACKGROUND

Treating bipolar chondral lesions in the patellofemoral (PF) compartment is a challenging problem. There are few reports available on the treatment of bipolar chondral lesions in the PF compartment.

PURPOSE

To evaluate the clinical outcomes and graft survivorship after autologous chondrocyte implantation (ACI) for the treatment of bipolar chondral lesions in the PF compartment.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The authors evaluated 58 patients who had ACI by a single surgeon for the treatment of symptomatic bipolar chondral lesions in the PF compartment between November 1995 and June 2014. All 58 patients (60 knees; mean age, 36.6 years) were included with a minimum 2-year follow-up. The mean ± SD sizes of the patellar and trochlear lesions were 5.6 ± 2.7 cm² and 4.2 ± 2.8 cm², respectively. Forty-two patients had osteotomy, as they had PF lateral maltracking, patellar instability, or tibiofemoral malalignment. Patients were evaluated with the modified Cincinnati Knee Rating Scale, Western Ontario and McMaster Universities Osteoarthritis Index, visual analog scale, the 36-Item Short Form Health Survey, and a patient satisfaction survey. Radiographs were evaluated with the Iwano classification.

RESULTS

Overall, the survival rates were 83% and 79% at 5 and 10 years, respectively. Of the 49 (82%) knees with retained grafts, all functional scores significantly improved postoperatively with a very high satisfaction rate (88%) at a mean 8.8 ± 4.2 years after ACI (range, 2-16 years). At the most recent follow-up, 28 of 49 successful knees were radiographically assessed (mean, 4.9 years; range, 2-17 years), with no increase of the Iwano classification in 26 knees. Outcomes for 11 patients were considered failures at a mean 2.9 years. Forty-two knees (70%) required a mean 1.0 subsequent surgical procedure. The primary reasons for chondroplasty were hypertrophy of the ACI graft (17; periosteum in 14, collagen membrane in 3), delamination of the ACI graft (5; periosteum in 4, collagen membrane in 1), and new chondral lesions (3). The best survival rates were observed among patients who underwent ACI with concomitant tibial tubercle osteotomy (TTO) as the first procedure without previous failed TTO and/or marrow stimulation technique (91% at 5 and 10 years), while the worst survival rates were observed among patients who had previous marrow stimulation (43% at 5 and 10 years).

CONCLUSION

Results demonstrated that ACI with concomitant osteotomy, when it is necessary for the treatment of bipolar/kissing lesions in the PF compartments, gives significant improvement in pain and function, with good survival rates at 5 and 10 years (83% and 79%, respectively). The high patient satisfaction rate is encouraging, and a high survival rate can be expected when ACI with a concomitant TTO is performed at the initial surgery for this difficult condition.

A high level of satisfaction after bicompartmental individualized knee arthroplasty with patient-specific implants and instruments

PURPOSE

Customized Individually Made (CIM) Bicompartmental Knee Arthroplasty (BKA) implants and three-dimensional printed customized instruments are available to fit to each patient's unique anatomy, medial or lateral with patellofemoral. This study aimed to evaluate the clinical outcomes after CIM-BKA.

METHODS

Fifty-five patients [59 knees; average age, 51 years; standard deviation (SD), 6.8; range 37-65 years] who underwent CIM-BKA were evaluated over an average of 3.8-year follow-up (SD 1.6; range 1-6 years). Forty-one knees underwent BKA combined medial and patellofemoral replacement (BKA-MP) and 18 knees underwent BKA combined lateral with patellofemoral replacement (BKA-LP). Survival rates, the modified Cincinnati Knee Rating Scale, WOMAC, VAS, SF-36, a satisfaction survey, and radiographic evaluation were used to evaluate outcomes.

RESULTS

Overall, survival rates were 98% and 92% at 2 and 5 years, respectively. Of 56 knees (95%) that did not fail, all patient-reported functional scores significantly improved post-operatively (P < 0.01), regardless of the previous surgeries, with a high level of satisfaction (51/56 knees, 91%). Radiographically, all the femoral components fit perfectly and 56 knees (95%) of the tibial components fit with less than 2 mm of undercoverage or overhang. Three knees (5%) required the conversion to TKA and 17 knees (29%) required subsequent surgical procedures, of which multiply operated knees had higher rate than virgin knee [14/40 (35%) vs. 3/16 (19%)].

CONCLUSION

CIM-BKA allowed precise fit of the components and provided a significant improvement post-operatively with a high level of satisfaction over short- to mid-term follow-up. This novel CIM-BKA is resurfacing, and does not require 10-mm faceted cuts, being only 3-mm-thick, which preserves bone stock for the future. It may be a promising option for relatively young active patients with bicompartmental osteoarthritis with a longer term follow-up being necessary.

LEVEL OF EVIDENCE

IV.

Autologous Chondrocyte Implantation for Bipolar Chondral Lesions in the Tibiofemoral Compartment

BACKGROUND

Treating bipolar chondral lesions in the tibiofemoral (TF) compartment with cartilage repair procedures is challenging, and a suitable treatment remains unclear.

PURPOSE

To evaluate clinical outcomes after autologous chondrocyte implantation (ACI) for the treatment of bipolar chondral lesions in the TF compartment.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

We evaluated 57 patients who underwent ACI for the treatment of symptomatic bipolar chondral lesions in the TF compartment by a single surgeon between October 1995 and June 2014. One patient did not return for follow-up. Thus, 56 patients (58 knees) were included with a minimum of 2 years' follow-up. A mean of 3.1 lesions per knee were treated, representing a mean total surface area of 16.1 cm² (range, 3.2-44.5 cm²) per knee. Bipolar lesions were present in the medial compartment (32 knees) and in the lateral compartment (26 knees). Patients were evaluated with the modified Cincinnati Knee Rating Scale, visual analog scale for pain, Western Ontario and McMaster Universities Osteoarthritis Index, and Short Form-36. Patients also answered questions regarding self-rated knee function and satisfaction with the procedure. Standard radiographs were evaluated with the Kellgren-Lawrence grading system.

RESULTS

The survival rate was 80% at 5 years and 76% at 10 years. A significantly better survival rate was found in patients with the use of a collagen membrane than periosteum (97% vs 61% at 5 years, respectively; P = .0014). Of 46 knees with retained grafts, all functional scores significantly improved postoperatively, with a very high satisfaction rate (91%) at a mean of 8.3 ± 5.1 years (range, 2-20 years) after ACI. At last follow-up, 24 of 46 successful knees were radiographically assessed (mean, 5.5 ± 4.0 years [range, 2.0-18.7 years]) and showed no significant osteoarthritis progression ( P = .3173). Outcomes for 12 patients were considered as failures at a mean of 4.1 years. Of these, 9 patients were converted to partial or total knee arthroplasty at a mean of 4.4 years. Two patients underwent revision ACI at 5 and 17 months. The other 1 patient did not require revision surgery.

CONCLUSION

Our study showed that ACI for the treatment of bipolar chondral lesions in the TF compartment provided successful clinical outcomes in patients with retained grafts and possibly prevented or delayed osteoarthritis progression at midterm to long-term follow-up. A collagen membrane is more encouraging than periosteum for bipolar lesions in the TF compartment. While addressing the predisposing factors affecting cartilage repair, ACI could be an adequate salvage procedure for bipolar chondral lesions in the TF compartment for the relatively young arthritic patient who wishes to avoid arthroplasty.

Influence of Mechanical Unloading on Articular Chondrocyte Dedifferentiation

Due to the limited self-repair capacity of articular cartilage, the surgical restoration of defective cartilage remains a major clinical challenge. The cell-based approach, which is known as autologous chondrocyte transplantation (ACT), has limited success, presumably because the chondrocytes acquire a fibroblast-like phenotype in monolayer culture. This unwanted dedifferentiation process is typically addressed by using three-dimensional scaffolds, pellet culture, and/or the application of exogenous factors. Alternative mechanical unloading approaches are suggested to be beneficial in preserving the chondrocyte phenotype. In this study, we examined if the random positioning machine (RPM) could be used to expand chondrocytes in vitro such that they maintain their phenotype. Bovine chondrocytes were exposed to (a) eight days in static monolayer culture; (b) two days in static monolayer culture, followed by six days of RPM exposure; and, (c) eight days of RPM exposure. Furthermore, the experiment was also conducted with the application of 20 mM gadolinium, which is a nonspecific ion-channel blocker. The results revealed that the chondrocyte phenotype is preserved when chondrocytes go into suspension and aggregate to cell clusters. Exposure to RPM rotation alone does not preserve the chondrocyte phenotype. Interestingly, the gene expression (mRNA) of the mechanosensitive ion channel TRPV4 decreased with progressing dedifferentiation. In contrast, the gene expression (mRNA) of the mechanosensitive ion channel TRPC1 was reduced around fivefold to 10-fold in all of the conditions. The application of gadolinium had only a minor influence on the results. This and previous studies suggest that the chondrocyte phenotype is preserved if cells maintain a round morphology and that the ion channel TRPV4 could play a key role in the dedifferentiation process.

Chondrogenic Potential of Dedifferentiated Rat Chondrocytes Reevaluated in Two- and Three-Dimensional Culture Conditions

For the cartilage repair, the cell sources currently adopted are primarily chondrocytes or mesenchymal stem cells (MSCs). Due to the fact that chondrocytes dedifferentiate during 2-dimensional (2D) expansion, MSCs are generally more studied and considered to have higher potential for cartilage repair purposes. Here we question if the dedifferentiated chondrocytes can regain the chondrogenic potential, to find potential applications in cartilage repair. For this we chose chondrocytes at passage 12 (considered to have sufficiently dedifferentiated) and the expression of chondrogenic phenotypes and matrix syntheses were examined over 14 days. In particular, the chondrogenic potential of MSCs was also compared. Results showed that the dedifferentiated chondrocytes proliferated actively over 14 days with almost 2.5-fold increase relative to MSCs. Moreover, the chondrogenic ability of chondrocytes was significantly higher than that of MSCs, as confirmed by the expression of a series of mRNA levels and the production of cartilage extracellular matrix molecules in 2D-monolayer and 3-dimensional (3D)-spheroid cultures. Of note, the significance was higher in 3D-culture than in 2D-culture. Although more studies are needed such as the use of different cell passages and human cell source, and the chondrogenic confirmation under in vivo conditions, this study showing that the dedifferentiated chondrocytes can also be a suitable cell source for the cell-based cartilage repair, as a counterpart of MSCs, will encourage further studies regarding this issue.

Good clinical and MRI outcome after arthroscopic autologous chondrocyte implantation for cartilage repair in the knee

PURPOSE

To analyze the clinical outcome and cartilage regeneration after all-arthroscopic Autologous Chondrocyte Implantation (ACI) using chondrospheres® (ACT3D) for the treatment of full-size articular cartilage lesions at the knee.

METHODS

Thirty consecutive patients treated by all-arthroscopic ACI for full-size articular cartilage lesions in an otherwise healthy knee were enrolled. The defects were located on the femoral condyles (n = 18), in the trochlea (n = 7) and at the patella (n = 5). Follow-up consisted of a clinical evaluation with assessment of subjective scores. Patient satisfaction was evaluated on a visual analog scale (VAS). 3-Tesla MRI and T2 mapping of the operated and the contralateral healthy knees were included to control the quality of the regenerated cartilage. The MOCART score was assessed by three blinded independent radiologists.

RESULTS

At the mean follow-up of 3 years ± 10.2 months 26 of the 30 patients (86.6%) were subjectively highly satisfied with the surgical result and assured they would undergo the same procedure again. The mean Lysholm score increased to 77.7 ± 14.6, the mean subjective IKDC significantly to 84.2 ± 5.6 (p < 0.05) and all five subgroups of the KOOS improved significantly (p < 0.05). The subjective outcome was not influenced by the duration of symptoms, age, location, size of defects nor dose of spheroids. The modified MOCART score was a mean of 60 ± 21 (0-80) points. Twenty-four patients (82.7%) were rated higher than 60 points. T2 mapping documented similar cartilage quality of the area of the ACI and the same location at the contralateral knee. Three patients had a MOCART score of 0 with few or no cartilage regeneration on MRI and were considered as failure of the ACI.

CONCLUSION

In this small cohort of 30 patients, minimal invasive all-arthroscopic ACT 3D using spheroids led to convincing clinical short-to-mid-term results with a significant increase in patients quality of life, satisfaction, reduction of pain, and improvement in knee function. The high morphologic integrity and quality of the ACI was reconfirmed by the Mocart Score and T2 mapping.

LEVEL OF EVIDENCE

IV.

Autologous chondrocyte implantation in the knee: systematic review and economic evaluation

BACKGROUND

The surfaces of the bones in the knee are covered with articular cartilage, a rubber-like substance that is very smooth, allowing frictionless movement in the joint and acting as a shock absorber. The cells that form the cartilage are called chondrocytes. Natural cartilage is called hyaline cartilage. Articular cartilage has very little capacity for self-repair, so damage may be permanent. Various methods have been used to try to repair cartilage. Autologous chondrocyte implantation (ACI) involves laboratory culture of cartilage-producing cells from the knee and then implanting them into the chondral defect.

OBJECTIVE

To assess the clinical effectiveness and cost-effectiveness of ACI in chondral defects in the knee, compared with microfracture (MF).

DATA SOURCES

A broad search was done in MEDLINE, EMBASE, The Cochrane Library, NHS Economic Evaluation Database and Web of Science, for studies published since the last Health Technology Assessment review.

REVIEW METHODS

Systematic review of recent reviews, trials, long-term observational studies and economic evaluations of the use of ACI and MF for repairing symptomatic articular cartilage defects of the knee. A new economic model was constructed. Submissions from two manufacturers and the ACTIVE (Autologous Chondrocyte Transplantation/Implantation Versus Existing Treatment) trial group were reviewed. Survival analysis was based on long-term observational studies.

RESULTS

Four randomised controlled trials (RCTs) published since the last appraisal provided evidence on the efficacy of ACI. The SUMMIT (Superiority of Matrix-induced autologous chondrocyte implant versus Microfracture for Treatment of symptomatic articular cartilage defects) trial compared matrix-applied chondrocyte implantation (MACI^®) against MF. The TIG/ACT/01/2000 (TIG/ACT) trial compared ACI with characterised chondrocytes against MF. The ACTIVE trial compared several forms of ACI against standard treatments, mainly MF. In the SUMMIT trial, improvements in knee injury and osteoarthritis outcome scores (KOOSs), and the proportion of responders, were greater in the MACI group than in the MF group. In the TIG/ACT trial there was improvement in the KOOS at 60 months, but no difference between ACI and MF overall. Patients with onset of symptoms < 3 years' duration did better with ACI. Results from ACTIVE have not yet been published. Survival analysis suggests that long-term results are better with ACI than with MF. Economic modelling suggested that ACI was cost-effective compared with MF across a range of scenarios.

LIMITATIONS

The main limitation is the lack of RCT data beyond 5 years of follow-up. A second is that the techniques of ACI are evolving, so long-term data come from trials using forms of ACI that are now superseded. In the modelling, we therefore assumed that durability of cartilage repair as seen in studies of older forms of ACI could be applied in modelling of newer forms. A third is that the high list prices of chondrocytes are reduced by confidential discounting. The main research needs are for longer-term follow-up and for trials of the next generation of ACI.

CONCLUSIONS

The evidence base for ACI has improved since the last appraisal by the National Institute for Health and Care Excellence. In most analyses, the incremental cost-effectiveness ratios for ACI compared with MF appear to be within a range usually considered acceptable. Research is needed into long-term results of new forms of ACI.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014013083.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Autologous Chondrocyte Implantation "Sandwich" Technique Compared With Autologous Bone Grafting for Deep Osteochondral Lesions in the Knee

BACKGROUND

Treating symptomatic osteochondral defects is challenging, especially in young adults with deep (>8-10 mm) empty defects after osteochondritis dissecans (OCD) or collapsed condyles secondary to avascular necrosis (AVN). For this population, osteoarthritis (OA) is inevitable if articular congruence is not restored.

PURPOSE

To describe the autologous chondrocyte implantation (ACI) "sandwich" technique with autologous bone grafting (ABG) and compare it with ABG alone for restoration of the osteochondral unit. The midterm to long-term outcomes in patients after the treatment for OCD and AVN will be reported and compared.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The outcomes for a consecutive cohort of 24 patients who underwent combined ABG with the ACI sandwich technique between 2001 and 2013 (ACI sandwich group) was compared with a historical control group of 17 consecutive patients who underwent ABG alone between 1995 and 2002 (ABG group) by a single surgeon for symptomatic deep (>8 mm) osteochondral lesions. Patients who were followed up with a minimum of 2 years were included in this study. The modified Cincinnati Knee Rating System, the Western Ontario and McMaster Universities Osteoarthritis Index, a visual analog scale (VAS), the Short Form-36, and a patient satisfaction survey were used to evaluate clinical outcomes. Survival analysis was performed using the Kaplan-Meier method, with no clinical improvement, graft failure, or conversion to prosthetic arthroplasty as the endpoint (failure). Kellgren-Lawrence (K-L) grading to assess OA progression was also performed.

RESULTS

In the ABG group, 13 of 17 patients (76%) were available with a mean follow-up of 15.7 years postoperatively (range, 5-21 years). In the ACI sandwich group, all 24 patients were available with a mean follow-up of 7.8 years postoperatively (range, 2-15 years). No significant differences were observed between the groups in terms of age, sex, side of the operated knee, body mass index, lesion type, lesion size, lesion depth, lesion location, or the need for realignment osteotomy. Eight patients (62%) were considered failures in the ABG group, while 3 patients (13%) were considered failures in the ACI sandwich group. The survival rate was significantly better in the ACI sandwich group than the ABG group (87% vs 54% at 5 years, respectively; P = .0025). All functional scores in patients with retained grafts significantly improved in the ACI sandwich group, whereas only the VAS score showed significant improvement in the ABG group. The patient satisfaction survey showed a very high satisfaction rate in the ACI sandwich group, with over 90% of patients reporting their knees as good or excellent and being satisfied with the procedure. In the ACI sandwich group, K-L grading demonstrated no significant OA progression from preoperatively to a mean 5.1 years postoperatively.

CONCLUSION

Our study showed that the ACI sandwich technique provided excellent and superior survival rates compared to ABG alone and significant improvements over midterm to long-term follow-up. This unique treatment offers native joint preservation for conditions that naturally will progress to OA and eventually require prosthetic arthroplasty.

Do Outcomes of Osteochondral Allograft Transplantation Differ Based on Age and Sex? A Comparative Matched Group Analysis

BACKGROUND

The effect of patient age or sex on outcomes after osteochondral allograft transplantation (OCA) has not been assessed.

PURPOSE

To determine clinical outcomes for male and female patients aged ≥40 years undergoing OCA compared with a group of patients aged <40 years.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A review of prospectively collected data of consecutive patients who underwent OCA by a single surgeon with a minimum follow-up of 2 years was conducted. The reoperation rate, failure rate, and patient-reported outcome scores were reviewed. All outcomes were compared between patients aged <40 or ≥40 years, with subgroup analyses conducted based on patient sex. Failure was defined as revision OCA, conversion to knee arthroplasty, or gross appearance of graft failure at second-look arthroscopic surgery. Descriptive statistics, Fisher exact or chi-square testing, and Mann-Whitney U testing were performed, with P < .05 set as significant.

RESULTS

A total of 170 patients (of 212 eligible patients; 80.2% follow-up) who underwent OCA with a mean follow-up of 5.0 ± 2.7 years (range, 2.0-15.1 years) were included, with 115 patients aged <40 years (mean age, 27.6 ± 7.3 years; 58 male, 57 female) and 55 patients aged ≥40 years (mean age, 44.9 ± 4.0 years; 33 male, 22 female). There were no differences in the number of pre-OCA procedures between the groups ( P = .085). There were no differences in the reoperation rate (<40 years: 38%; ≥40 years: 36%; P = .867), time to reoperation (<40 years: 2.12 ± 1.90 years; ≥40 years: 3.43 ± 3.43 years; P = .126), or failure rate (<40 years: 13%; ≥40 years: 16%; P = .639) between the older and younger groups. Patients in both groups demonstrated significant improvement in Lysholm (both: P < .001), International Knee Documentation Committee (IKDC) (both: P < .001), Knee Injury and Osteoarthritis Outcome Score (KOOS) (both: P < .001), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) (both: P < .001), and Short Form-12 (SF-12) physical (both: P < .001) scores compared with preoperative values. Patients aged ≥40 years demonstrated significantly higher KOOS symptom ( P = .015) subscores compared with patients aged <40 years. There were no significant differences in the number of complications, outcome scores, or time to failure between the sexes. In patients aged <40 years, female patients experienced failure significantly more quickly than male patients ( P = .039). In contrast, in patients aged ≥40 years, male patients experienced failure significantly more quickly than female patients ( P = .046).

CONCLUSION

This study provides evidence that OCA is a safe and reliable treatment option for osteochondral defects in patients aged ≥40 years. Male and female patients had similar outcomes. Patients aged <40 years demonstrated lower KOOS symptom subscores postoperatively compared with older patients, potentially attributable to higher expectations of return to function postoperatively as compared with older patients.

Biomaterials for articular cartilage tissue engineering: Learning from biology

Articular cartilage is commonly described as a tissue that is made of up to 80% water, is devoid of blood vessels, nerves, and lymphatics, and is populated by only one cell type, the chondrocyte. At first glance, an easy tissue for clinicians to repair and for scientists to reproduce in a laboratory. Yet, chondral and osteochondral defects currently remain an open challenge in orthopedics and tissue engineering of the musculoskeletal system, without considering osteoarthritis. Why do we fail in repairing and regenerating articular cartilage? Behind its simple and homogenous appearance, articular cartilage hides a heterogeneous composition, a high level of organisation and specific biomechanical properties that, taken together, make articular cartilage a unique material that we are not yet able to repair or reproduce with high fidelity. This review highlights the available therapies for cartilage repair and retraces the research on different biomaterials developed for tissue engineering strategies. Their potential to recreate the structure, including composition and organisation, as well as the function of articular cartilage, intended as cell microenvironment and mechanically competent replacement, is described. A perspective of the limitations of the current research is given in the light of the emerging technologies supporting tissue engineering of articular cartilage.

STATEMENT OF SIGNIFICANCE

The mechanical properties of articular tissue reflect its functionally organised composition and the recreation of its structure challenges the success of in vitro and in vivo reproduction of the native cartilage. Tissue engineering and biomaterials science have revolutionised the way scientists approach the challenge of articular cartilage repair and regeneration by introducing the concept of the interdisciplinary approach. The clinical translation of the current approaches are not yet fully successful, but promising results are expected from the emerging and developing new generation technologies.

A 20-Year Follow-up After First-Generation Autologous Chondrocyte Implantation

BACKGROUND

Treating articular cartilage defects is a demanding problem. Although several studies have reported durable and improved clinical outcomes after autologous chondrocyte implantation (ACI) over a long-term period, there is no report with over 20 years' follow-up.

PURPOSE

To evaluate clinical outcomes after first-generation ACI for the treatment of knees with disabling, large single and multiple cartilage defects for which patients wished to avoid prosthetic arthroplasty, with a minimum of 20 years' follow-up.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The authors reviewed prospectively collected data from 23 patients (24 knees; mean age, 35.4 years [range, 13-52 years]) undergoing ACI for the treatment of symptomatic, full-thickness articular cartilage lesions. A mean of 2.1 lesions per knee were treated over a mean total surface area of 11.8 cm² (range, 2.4-30.5 cm²) per knee. Kaplan-Meier survival analysis and functional outcome scores, including the modified Cincinnati Knee Rating System, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Short Form-36 (SF-36), were used. Patients also self-reported an improvement in pain with a visual analog scale and a satisfaction survey.

RESULTS

The 20-year survival rate was 63% (95% CI, 40%-78%). The evaluation of the 15 knees with retained grafts demonstrated that all clinical scores except the WOMAC subscore for stiffness and SF-36 mental component summary score improved significantly and were sustained to 20 years postoperatively. Ninety-three percent of these patients rated knee-specific outcomes as good or excellent. The outcomes for 9 of 24 knees were considered failures, including 5 undergoing revision ACI and 4 being converted to arthroplasty at a mean of 1.7 and 5.9 years, respectively. Only 1 of 5 knees that underwent revision ACI was converted to arthroplasty at 1.9 years after the index surgery, and the other 4 patients were able to maintain their biological knee. Overall, 20 years later, 79% of patients maintained their native knee, for which they initially sought treatment, and were satisfied when evaluated.

CONCLUSION

First-generation ACI provided satisfactory survival rates and significant clinical improvements over a 20-year follow-up, which offers an important standard for comparison with newer-generation ACI technologies of the future.

Failure of Autologous Chondrocyte Implantation

Long-term results of autologous chondrocyte implantation and matrix-assisted autologous chondrocyte transplantation in the knee are satisfying, but not enough attention has been paid to the evaluation of failures. Thus, a systematic review of the literature was performed, underlining a failure rate in the 58 included articles of 14.9% among 4294 patients, most of them occurring in the first 5 years after surgery, and with no difference between autologous chondrocyte implantation and matrix-assisted autologous chondrocyte transplantation. Failures are very heterogenously defined in the current literature. A widely accepted definition is needed, and a comprehensive definition taking into consideration the patient's perception of the outcome, not just the surgeon's or researcher's point of view, would be advisable. Finally, there is no agreement on the most appropriate treatment of failures, and further studies are needed to give better indications to properly manage patients failed after cartilage procedures.

LEVEL OF EVIDENCE

Level IV.

Long-term Outcomes of Autologous Chondrocyte Implantation in Adolescent Patients

BACKGROUND

Treating symptomatic articular cartilage lesions is challenging, especially in adolescent patients, because of longer life expectancies and higher levels of functional activity. For this population, long-term outcomes after autologous chondrocyte implantation (ACI) remain to be determined.

PURPOSE

To evaluate long-term outcomes in adolescents after ACI using survival analyses, validated outcome questionnaires, and standard radiographs.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

We performed a review of prospectively collected data from patients who underwent ACI between 1996 and 2013. We evaluated 27 patients aged <18 years old (29 knees; mean age, 15.9 years) who were treated by a single surgeon for symptomatic, full-thickness articular cartilage lesions over a mean 9.6-year follow-up (median, 13 years; range, 2-19 years). A mean of 1.5 lesions per knee were treated over a mean total surface area of 6.2 cm² (range, 2.0-23.4 cm²) per knee. Survival analysis was performed using the Kaplan-Meier method, with graft failure as the end point. The modified Cincinnati Knee Rating Scale, Western Ontario and McMaster Universities Osteoarthritis Index, visual analog scale, and Short Form 36 scores were used to evaluate clinical outcomes. Patients also self-reported knee function and satisfaction. Standard radiographs were evaluated using Kellgren-Lawrence grades.

RESULTS

Both 5- and 10-year survival rates were 89%. All clinical scores improved significantly postoperatively. A total of 96% of patients rated knee function as better after surgery, and all patients indicated that they would undergo the same surgery again. Approximately 90% rated knee-specific outcomes as good or excellent and were satisfied with the procedure. At last follow-up, 12 of 26 successful knees were radiographically assessed (mean, 5.6 years postoperatively), with no significant osteoarthritis progression. Three knees were considered failures, which were managed by autologous bone grafting or osteochondral autologous transplantation. Twenty knees required subsequent surgical procedures. These were primarily associated with periosteum and were arthroscopically performed.

CONCLUSION

ACI resulted in satisfactory survival rates and significant improvements in function, pain, and mental health for adolescent patients over a long-term follow-up. ACI was associated with very high satisfaction postoperatively, despite the subsequent procedure rate being relatively high primarily because of the use of periosteum. If periosteum is used, this rate should be a consideration when discussing ACI with patients and their parents.

Advances and Prospects in Stem Cells for Cartilage Regeneration

The histological features of cartilage call attention to the fact that cartilage has a little capacity to repair itself owing to the lack of a blood supply, nerves, or lymphangion. Stem cells have emerged as a promising option in the field of cartilage tissue engineering and regenerative medicine and could lead to cartilage repair. Much research has examined cartilage regeneration utilizing stem cells. However, both the potential and the limitations of this procedure remain controversial. This review presents a summary of emerging trends with regard to using stem cells in cartilage tissue engineering and regenerative medicine. In particular, it focuses on the characterization of cartilage stem cells, the chondrogenic differentiation of stem cells, and the various strategies and approaches involving stem cells that have been used in cartilage repair and clinical studies. Based on the research into chondrocyte and stem cell technologies, this review discusses the damage and repair of cartilage and the clinical application of stem cells, with a view to increasing our systematic understanding of the application of stem cells in cartilage regeneration; additionally, several advanced strategies for cartilage repair are discussed.

Biological Knee Reconstruction With Concomitant Autologous Chondrocyte Implantation and Meniscal Allograft Transplantation: Mid- to Long-term Outcomes

BACKGROUND

Treating articular cartilage defects and meniscal deficiency is challenging. Although some short- to mid-term follow-up studies report good clinical outcomes after concurrent autologous chondrocyte implantation (ACI) and meniscal allograft transplantation (MAT), longer follow-up is needed.

PURPOSE

To evaluate mid- to long-term outcomes after combined ACI with MAT.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

We performed a retrospective review of prospectively gathered data from patients who had undergone ACI with MAT between 1999 and 2013. A single surgeon treated 18 patients for symptomatic full-thickness chondral defects with meniscal deficiency. One patient was lost to follow-up. Thus, 17 patients (18 knees; mean age, 31.7 years) were evaluated over a mean 7.9-year follow-up (range, 2-16 years). A mean 1.8 lesions per knee were treated over a total surface area of 7.6 cm² (range, 2.3-21 cm²) per knee. Seventeen lateral and 1 medial MATs were performed. Survival was analyzed using the Kaplan-Meier method. The modified Cincinnati Knee Rating Scale, Western Ontario and McMaster Universities Osteoarthritis Index, visual analog scale, and Short Form-36 were used to evaluate clinical outcomes. Patients also self-reported knee function and satisfaction. Standard radiographs were scored for Kellgren-Lawrence (K-L) grade.

RESULTS

Both 5- and 10-year survival rates were 75%. Outcomes for 6 knees were considered failures. Of the 6 failures, 4 knees were converted to arthroplasty and the other 2 knees underwent biological revision surgery. Of the 12 successfully operated knees, all clinical measures significantly improved postoperatively. Ten patients representing 11 of the 12 knees rated outcomes for their knees as good or excellent, and 1 rated their outcome as fair. Eight patients representing 9 of the 12 knees were satisfied with the procedure. There was no significant osteoarthritis progression based on K-L grading from preoperatively to a mean 5.9 years after surgery. Seven of the 12 knees (58%) required subsequent surgical procedures (5 arthroscopic alone, 2 both arthroscopic and open).

CONCLUSION

Combined ACI with MAT provided significant improvement in 65% of the operated knees over a mid- to long-term follow-up. This procedure can allow patients to retain their biological knees, delay or prevent rapid degeneration to osteoarthritis, and could be recognized as a bridge procedure before artificial knee replacement. However, careful discussion between the patient and surgeon is necessary before surgery to ensure realistic expectations.

Feasibility of conducting a web-based survey of patient-reported outcomes and rehabilitation progress

Background

Web-based surveys provide an efficient means to track clinical outcomes over time without the use of clinician time for additional paperwork. Our purpose was to determine the feasibility of utilizing web-based surveys to capture rehabilitation compliance and clinical outcomes among postoperative orthopedic patients. The study hypotheses were that (a) recruitment rate would be high (>90%), (b) patients receiving surveys every two weeks would demonstrate higher response rates than patients that receive surveys every four weeks, and (c) response rates would decrease over time.

Methods

The study deaign involved a longitudinal cohort. Surgical knee patients were recruited for study participation during their first post-operative visit (n = 59, 34.9 ± 12.0 years of age). Patients with Internet access, an available email address and willingness to participate were counter-balanced into groups to receive surveys either every two or four weeks for 24 weeks post-surgery. The surveys included questions related to rehabilitation and questions from standard patient-reported outcome measures. Outcome measures included recruitment rate (participants consented/patients approached), eligibility (participants with email/participants consented), willingness (willing participants/participants eligible), and response rate (percentage of surveys completed by willing participants).

Results

Fifty-nine patients were approached regarding participation. Recruitment rate was 98% (n = 58). Eligibility was 95% (n = 55), and willingness was 91% (n = 50). The average response rate was 42% across both groups. There was no difference in the median response rates between the two-week (50%, range 0–100%) and four-week groups (33%, range 0–100%; p = 0.55).

Conclusions

Although patients report being willing and able to participate in a web-based survey, response rates failed to exceed 50% in both the two-week and four-week groups. Furthermore, response rates began to decrease after the first three months postoperatively. Therefore, supplementary data collection procedures may be necessary to meet established research quality standards.

Comparison of natural crosslinking agents for the stabilization of xenogenic articular cartilage

Osteochondral xenografts are potentially inexpensive, widely available alternatives to fresh allografts. However, antigen removal from xenogenic cartilage may damage the extracellular matrix and reduce compressive stiffness. Non-crosslinked xenogenic cartilage may also undergo rapid enzymatic degradation in vivo. We hypothesized that natural crosslinking agents could be used in place of glutaraldehyde to improve the mechanical properties and enzymatic resistance of decellularized cartilage. This study compared the effects of genipin (GNP), proanthocyanidin (PA), and epigallocatechin gallate (EGCG), on the physical and mechanical properties of decellularized porcine cartilage. Glutaraldehyde (GA) served as a positive control. Porcine articular cartilage discs were decellularized in 2% sodium dodecyl sulfate and DNase I followed by fixation in 0.25% GNP, 0.25% PA, 0.25% EGCG, or 2.5% GA. Decellularization decreased DNA by 15% and GAG by 35%. For natural crosslinkers, the average degree of crosslinking ranged from approximately 50% (EGCG) to 78% (GNP), as compared to 83% for the GA control. Among the natural crosslinkers, only GNP significantly affected the disc diameter, and shrinkage was under 2%. GA fixation had no significant effect on disc diameter. Decellularization decreased aggregate modulus; GA and GNP, but not EGCG and PA, were able to restore it to its original level. GNP, PA, and GA conferred a similar, almost complete resistance to collagenase degradation. EGCG also conferred substantial resistance but to a lesser degree. Overall, the data support our hypothesis and suggest that natural crosslinkers may be suitable alternatives to glutaraldehyde for stabilization of decellularized cartilage. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1037-1046, 2016.

Patients Scheduled for Chondrocyte Implantation Treatment with MACI Have Larger Defects than Those Enrolled in Clinical Trials

OBJECTIVE

To compare characteristics for patients scheduled for autologous chondrocyte implantation with matrix-assisted chondrocyte implantation (MACI) with those enrolled in clinical trials and to describe differences in patient selection between countries.

DESIGN

Anonymized data from patients scheduled for MACI treatment in the knee in Europe and Australia/Asia were obtained from the Genzyme/Sanofi database. Average age, defect size, and male-female ratio were analyzed and compared by country. Clinical cohort studies and prospective comparative trials using autologous chondrocyte implantation and related treatments were identified and weighted average age, weighted defect size, and male-female ratio were analyzed and compared with data from the database.

RESULTS

From the database 2,690 patients were included with mean age 33.7 years and male-female ratio of 67:33. Mean defect size was 5.64 cm(2) and 70% of the defects were 3 to 10 cm(2). There were significant differences between patients' mean defect sizes between countries. Sixty-nine studies (57 cohorts and 12 prospective comparative trials) with a total of 5,449 patients were identified. The combined weighted mean age was 34.2 years, and the combined weighted mean defect size was 4.89 cm(2). Patients scheduled for MACI had significantly larger defects that those included in clinical trials. There was no significant difference in age. No differences were found between cohorts and prospective comparative trials.

CONCLUSION

The vast majority of patients scheduled for autologous chondrocyte implantation with MACI have chondral defect comparable to that generally recommended, but differences exist between countries. Patients enrolled in clinical trials have significantly smaller defects than those undergoing treatment outside controlled trials.

TGF-β1, GDF-5, and BMP-2 stimulation induces chondrogenesis in expanded human articular chondrocytes and marrow-derived stromal cells

Replacement of degenerated cartilage with cell-based cartilage products may offer a long-term solution to halt arthritis' degenerative progression. Chondrocytes are frequently used in cell-based FDA-approved cartilage products; yet human marrow-derived stromal cells (hMSCs) show significant translational potential, reducing donor site morbidity and maintaining their undifferentiated phenotype with expansion. This study sought to investigate the effects of transforming growth factor β1 (TGF-β1), growth/differentiation factor 5 (GDF-5), and bone morphogenetic protein 2 (BMP-2) during postexpansion chondrogenesis in human articular chondrocytes (hACs) and to compare chondrogenesis in passaged hACs with that of passaged hMSCs. Through serial expansion, chondrocytes dedifferentiated, decreasing expression of chondrogenic genes while increasing expression of fibroblastic genes. However, following expansion, 10 ng/mL TGF-β1, 100 ng/mL GDF-5, or 100 ng/mL BMP-2 supplementation during three-dimensional aggregate culture each upregulated one or more markers of chondrogenic gene expression in both hACs and hMSCs. Additionally, in both cell types, the combination of TGF-β1, GDF-5, and BMP-2 induced the greatest upregulation of chondrogenic genes, that is, Col2A1, Col2A1/Col1A1 ratio, SOX9, and ACAN, and synthesis of cartilage-specific matrix, that is, glycosaminoglycans (GAGs) and ratio of collagen II/I. Finally, TGF-β1, GDF-5, and BMP-2 stimulation yielded mechanically robust cartilage rich in collagen II and GAGs in both cell types, following 4 weeks maturation. This study illustrates notable success in using the self-assembling method to generate robust, scaffold-free neocartilage constructs using expanded hACs and hMSCs.

Matrix-induced autologous chondrocyte implantation (MACI) in the knee: clinical outcomes and challenges

PURPOSE

Matrix-induced autologous chondrocyte implantation (MACI) has demonstrated effectiveness in treating isolated cartilage defects of the knee but medium- and long-term evidence and information on the management of postoperative complications or partially successful cases are sparse. This study hypothesised that MACI is effective for up to 5 years and that patients with posttreatment problems may go on to obtain clinical benefit from other interventions.

METHODS

A follow-on, prospective case series of patients recruited into a previous controlled, randomised, prospective study or newly enroled. Patients were followed up 6, 12, 24 and 60 months after surgery. Outcome measures were Tegner (activity levels) and Lysholm (pain, stability, gait, clinical symptoms) scores. Zone-specific subgroups were analysed 6, 12 and 24 months postoperatively.

RESULTS

Sixty-five patients were treated with MACI. Median Tegner score improved from II to IV at 12 months; an improvement maintained to 60 months. Mean Lysholm score improved from 28.5 to 76.6 points (±19.8) at 24 months, settling back to 75.5 points after 5 years (p > 0.0001). No significant differences were identified in the zone-specific analysis. Posttreatment issues (N = 12/18.5 %) were resolved with microfracture, debridement, OATS or bone grafting.

CONCLUSIONS

MACI is safe and effective in the majority of patients. Patients in whom treatment is only partially successful can go on to obtain clinical benefit from other cartilage repair options. This study adds to the clinical evidence on the MACI procedure, offers insight into likely treatment outcomes, and highlights MACI's usefulness as part of an armamentarium of surgical approaches to the treatment of isolated knee defects.

LEVEL OF EVIDENCE

Prospective case control study with no control group, Level III.

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.

A Road Map to Commercialization of Cartilage Therapy in the United States of America

Despite numerous efforts in cartilage regeneration, few products see the light of clinical translation as the commercialization process is opaque, financially demanding, and requires collaboration with people of varied skill sets. The aim of this review is to introduce, to an academic audience, the different paradigms involved in the commercialization of cartilage regeneration technology, elucidate the different hurdles associated with the use of cells and materials in developing new technologies, discuss potential commercialization strategies, and inform the reader about the current trends observed in both the clinical and laboratory setting for establishing clinical trials. Although there are review articles on articular cartilage tissue engineering, independent reports provided by the Food and Drug Administration, and separate review articles on animal models, this is the first review that encompasses all of these facets and is presented in a format favorable to the academic investigator interested in clinical translation from bench to bedside.

Long-term clinical results and MRI changes after autologous chondrocyte implantation in the knee of young and active middle aged patients

Background

Autologous chondrocyte implantation (ACI) represents a valid surgical option for symptomatic full-thickness chondral lesions of the knee. Here we report long-term clinical and MRI results of first-generation ACI.

Materials and methods

Fifteen patients (mean age 21.3 years) underwent first-generation ACI for symptomatic chondral defects of the knee between 1997 and 2001. The mean size of the lesions was 5.08 cm² (range 2–9 cm²). Patients were evaluated using the International Knee Documentation Committee (IKDC) Knee Examination Form, the Tegner Activity Scale, and the Knee Injury and Osteoarthritis Outcome Score (KOOS). High-resolution MRI was used to analyze the repair tissue with nine variables (the MOCART scoring system).

Results

The mean follow-up period was 148 months (range 125–177 months). ACI resulted in substantial improvements in all clinical outcome parameters, even as much as 12 years after implantation. A significant decrease in the MOCART score was recorded at final measurement. Reoperation was required in 2 patients; failure was caused by partial detachment of the graft in both cases.

Conclusion

Autologous chondrocyte implantation is an effective and durable solution for the treatment of large, full-thickness cartilage and osteochondral lesions, even in young and active middle-aged patients. High-resolution MRI is a useful and noninvasive method for evaluating the repaired tissue.

Level of evidence

IV.

Guided differentiation of bone marrow stromal cells on co-cultured cartilage and bone scaffolds

Focal chondral defects that result from traumatic injuries to the knee remain one of the most common causes of disability in patients. Current solutions for healing focal cartilage defects are mainly limited by the production of inferior cartilage-like tissue and subsequent delamination due to incomplete healing of the subchondral bone. In this experiment a polymeric osteochondral implant for guiding autologous bone marrow stem cells (BMSCs) to populate the scaffold to create distinctive bone and cartilage tissue is used. The cartilage component presents bioactive aligned nanofibers containing chondroitin sulfate and hyaluronic acid while the bone component includes hydroxyapatite to promote chondrogenic and osteogenic differentiation of the rat BMSCs in vitro. The different cartilage and bone components resulted in the elevated expression of osteogenic markers such as bone sialoprotein, runt related transcription factor 2, and bone morphogenetic protein 2 in the deeper bone layer and chondrogenic markers such as collagen type II and aggrecan in the cartilage layer. Through immunofluorescence imaging, the alignment of the secreted collagen type II fibrils and aggrecan was visualized and quantified on the cartilage component of the scaffold. These current studies show that the biodegradable biphasic osteochondral implant may be effective in promoting more hyaline-like tissue to fill in chondral defects of the knee.

Therapeutic Potential of Differentiated Mesenchymal Stem Cells for Treatment of Osteoarthritis

Osteoarthritis (OA) is a chronic, progressive, and irreversible degenerative joint disease. Conventional OA treatments often result in complications such as pain and limited activity. However, transplantation of mesenchymal stem cells (MSCs) has several beneficial effects such as paracrine effects, anti-inflammatory activity, and immunomodulatory capacity. In addition, MSCs can be differentiated into several cell types, including chondrocytes, osteocytes, endothelia, and adipocytes. Thus, transplantation of MSCs is a suggested therapeutic tool for treatment of OA. However, transplanted naïve MSCs can cause problems such as heterogeneous populations including differentiated MSCs and undifferentiated cells. To overcome this problem, new strategies for inducing differentiation of MSCs are needed. One possibility is the application of microRNA (miRNA) and small molecules, which regulate multiple molecular pathways and cellular processes such as differentiation. Here, we provide insight into possible strategies for cartilage regeneration by transplantation of differentiated MSCs to treat OA patients.

Next Generation Mesenchymal Stem Cell (MSC)-Based Cartilage Repair Using Scaffold-Free Tissue Engineered Constructs Generated with Synovial Mesenchymal Stem Cells

Because of its limited healing capacity, treatments for articular cartilage injuries are still challenging. Since the first report by Brittberg, autologous chondrocyte implantation has been extensively studied. Recently, as an alternative for chondrocyte-based therapy, mesenchymal stem cell-based therapy has received considerable research attention because of the relative ease in handling for tissue harvest, and subsequent cell expansion and differentiation. This review summarizes latest development of stem cell therapies in cartilage repair with special attention to scaffold-free approaches.

Meniscal allograft transplantation: a systematic review

BACKGROUND

Meniscal allograft transplantation (MAT) was developed as a means of treating the symptoms of compartmental overload after meniscectomy. Despite more than 20 years of research in this field, many controversies still exist regarding meniscal transplantation.

PURPOSE

The aims of this study were to assess (1) the quality of the published studies on MAT; (2) the indications for this type of surgery; (3) the methods used for preservation, sizing, and fixation of the allograft; and (4) the clinical and radiographic outcomes of this procedure and its role in preventing osteoarthritis.

STUDY DESIGN

Systematic review.

METHODS

Inclusion criteria for the articles were (1) English language, (2) peer-reviewed clinical studies with evidence levels 1 to 4, (3) reported clinical and/or radiological outcomes of MAT isolated or combined with other procedures, (4) minimum 12-month follow-up, (5) case series of at least 10 patients, and (6) a follow-up rate of at least 80% (no more than 20% of patients lost to follow-up).

RESULTS

A total of 55 studies matched the inclusion criteria (2 level 2, 7 level 3, and 46 level 4). The average Coleman methodology score was 49.73 ± 12.41 (range, 24-81). There was agreement in the literature regarding the indications for MAT: joint line pain and tenderness correlated with previous meniscectomy, young patients, without diffuse Outerbridge grade III and no grade IV cartilage damage, and a stable and well-aligned knee. Different graft types have been used: viable, fresh frozen, cryopreserved, and lyophilized. The most common method for graft sizing was plain radiography. Different fixation techniques have been described, with only a few studies comparing the clinical results of the different techniques and with no proven superiority of one method over the other. All the studies showed clinical improvement at last follow-up visit compared with preoperatively. The chondroprotective effect of MAT is still unclear.

CONCLUSION

Meniscal allograft transplantation seems to provide good clinical results at short-term and midterm follow-up, with improvement in knee function as well as acceptable complication and failure rates. Higher quality studies are necessary to better assess the potential chondroprotective effect of MAT and to identify differences in terms of outcomes between different surgical techniques.

Treatment of articular cartilage lesions of the knee by microfracture or autologous chondrocyte implantation: a systematic review

PURPOSE

We performed a systematic review of the treatment of articular cartilage lesions of the knee by microfracture or autologous chondrocyte implantation to determine the differences in patient outcomes after these procedures.

METHODS

We searched PubMed/Medline, Embase, and The Cochrane Library databases in the period from January 10 through January 20, 2013, and included 34 articles in our qualitative analysis.

RESULTS

All studies showed improvement in outcome scores in comparison with baseline values, regardless of the treatment modality. The heterogeneity of the results presented in the studies precluded a meta-analysis.

CONCLUSIONS

Microfracture appears to be effective in smaller lesions and is usually associated with a greater proportion of fibrocartilage production, which may have an effect on durability and eventual failure. Autologous chondrocyte implantation is an effective treatment that may result in a greater proportion of hyaline-like tissue at the repair site, which may in turn have a beneficial effect on durability and failure; it appears to be effective in larger lesions. Autologous chondrocyte implantation with periosteum has been shown to be associated with symptomatic cartilage hypertrophy more frequently than autologous chondrocyte implantation with collagen membrane. Matrix-associated autologous chondrocyte implantation is technically less challenging than the other techniques available, and in lesions greater than 4 cm(2), it has been shown to be more effective than microfracture.

LEVEL OF EVIDENCE

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

Long-term results of autologous chondrocyte implantation in the knee for chronic chondral and osteochondral defects

BACKGROUND

Autologous chondrocyte implantation (ACI) has been shown to be effective in the midterm for the treatment of symptomatic articular cartilage lesions of the knee, but few long-term series have been published. The multioperated chronic articular cartilage defect remains a difficult condition to treat.

PURPOSE

To examine the long-term clinical results of ACI for large chronic articular cartilage defects, many treated as salvage.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This is a prospective case series of 104 patients with a mean age of 30.2 years and a symptomatic lesion of the articular cartilage in the knee, who underwent ACI between 1998 and 2001. The mean duration of symptoms before surgery was 7.8 years. The mean number of previous surgical procedures on the cartilage defect, excluding arthroscopic debridement, was 1.3. The defects were large, with a mean size of 477.1 mm(2) (range, 120-2500 mm(2)). The modified Cincinnati, Stanmore/Bentley, and visual analog scale for pain scoring systems were used to assess pain and functional outcomes at a minimum 10 years (mean, 10.4 years; range, 10-12 years).

RESULTS

Twenty-seven patients (26%) experienced graft failure at a mean of 5.7 years after ACI. Of the 73 patients who did not fail, 46 patients (63% of patients with a surviving graft) had an excellent result, 18 (25%) were good, 6 (8%) were fair, and 3 (4%) had a poor result. Of a total of 100 patients successfully followed up, 98 were satisfied with the ACI technique for their chronic knee pain and would undergo the procedure again.

CONCLUSION

Autologous chondrocyte implantation can provide a long-term solution in more than 70% of young patients of a difficult-to-treat group with large chronic articular cartilage lesions, even in the salvage situation.

Satisfactory long-term MRI after autologous chondrocyte implantation at the knee

PURPOSE

Autologous chondrocyte implantation (ACI) to address isolated condylar lesions is supposed to limit degenerative deterioration in neutrally aligned knees. Here, we report long-term results of the first-generation ACI technique with periosteal flap.

METHODS

Twelve patients, 29 years old on average, were included on the basis of pre-operative MRI selection of lesions >2 cm2. Cartilage carrots were harvested arthroscopically, then cultured and finally re-implanted within a mean time interval of 12 weeks. Ten-year MRI results were analysed according to a semi-quantitative scale, along with functional assessment based on International Knee Documentation Committee score, Lysholm et al. score and the Tegner et al. activity scale.

RESULTS

One patient secondarily required valgus tibial osteotomy with mosaic plasty. Another incurred graft hypertrophy that necessitated arthroscopic peeling. MRI showed that cartilage repair filled more than 50% of the initial defect in 9 patients. Standard radiographs revealed slight narrowing of the joint line. Overall, functional scores improved durably by 50%, although activity level decreased substantially.

CONCLUSION

ACI contained degenerative changes within moderate stages while maintaining durable functional improvement. However, in the absence of controls, it was difficult to differentiate between these findings and the spontaneous evolution of non-treated lesions.

LEVEL OF EVIDENCE

Case series, Level IV.

Influence of response shift on early patient-reported outcomes following autologous chondrocyte implantation

PURPOSE

Response shift is the phenomenon by which an individual's standards for evaluation change over time. The purpose of this study was to determine whether patients undergoing autologous chondrocyte implantation (ACI) experience response shift.

METHODS

Forty-eight patients undergoing ACI participated. The "then-test" method was used to evaluate response shift in commonly used patient-reported outcome measures (PROMs)-the SF-36 Physical Component Scale (SF-36 PCS), WOMAC, IKDC, and Lysholm. Each PROM was completed pre- and 6 and 12 months post-surgery. At 6 and 12 months, an additional "then" version of each form was also completed. The "then" version was identical to the original except that patients were instructed to assess how they were prior to ACI. Traditional change, response shift adjusted change, and response shift magnitude were calculated at 6 and 12 months. T tests (p < 0.05) were used to compare traditional change to response-shift-adjusted change, and response shift magnitude values to previously established minimal detectable change.

RESULTS

There were no differences between traditional change and response-shift-adjusted change for any of the PROMs. The mean response shift magnitude value of the WOMAC at 6 months (15 ± 14, p = 0.047) was greater than the previously established minimal detectable change (10.9). The mean response shift magnitude value for the SF-36 PCS at 12 months (9.4 ± 6.8, p = 0.017) also exceeded the previously established minimal detectable change (6.6).

CONCLUSIONS

There was no evidence of a group-level effect for response shift. These results support the validity of pre-test/post-test research designs in evaluating treatment effects. However, there is evidence that response shifts may occur on a patient-by-patient basis, and scores on the WOMAC and SF-36 in particular may be influenced by response shift.

LEVEL OF EVIDENCE

II.

Evolution of autologous chondrocyte repair and comparison to other cartilage repair techniques

Articular cartilage defects have been addressed using microfracture, abrasion chondroplasty, or osteochondral grafting, but these strategies do not generate tissue that adequately recapitulates native cartilage. During the past 25 years, promising new strategies using assorted scaffolds and cell sources to induce chondrocyte expansion have emerged. We reviewed the evolution of autologous chondrocyte implantation and compared it to other cartilage repair techniques. Methods. We searched PubMed from 1949 to 2014 for the keywords “autologous chondrocyte implantation” (ACI) and “cartilage repair” in clinical trials, meta-analyses, and review articles. We analyzed these articles, their bibliographies, our experience, and cartilage regeneration textbooks. Results. Microfracture, abrasion chondroplasty, osteochondral grafting, ACI, and autologous matrix-induced chondrogenesis are distinguishable by cell source (including chondrocytes and stem cells) and associated scaffolds (natural or synthetic, hydrogels or membranes). ACI seems to be as good as, if not better than, microfracture for repairing large chondral defects in a young patient's knee as evaluated by multiple clinical indices and the quality of regenerated tissue. Conclusion. Although there is not enough evidence to determine the best repair technique, ACI is the most established cell-based treatment for full-thickness chondral defects in young patients.

Graft hypertrophy of matrix-based autologous chondrocyte implantation: a two-year follow-up study of NOVOCART 3D implantation in the knee

PURPOSE

Graft hypertrophy is a major complication in the treatment for localized cartilage defects with autologous chondrocyte implantation (ACI) using periosteal flap and its further development, Novocart (a matrix-based ACI procedure). The aim of the present study is to investigate individual criteria for the development of graft hypertrophy by NOVOCART 3D implantation of the knee in the post-operative course of 2 years.

METHODS

Forty-one consecutive patients with 44 isolated cartilage defects of the knee were treated with NOVOCART 3D implants. Individual criteria and defect-associated criteria were collected. Follow-up MRIs were performed at 3, 6, 12 and 24 months. The NOVOCART 3D implants were measured and classified. The modified MOCART Score was used to evaluate quality and integration of the NOVOCART 3D implants in MRI.

RESULTS

Graft hypertrophy was observed in a total of 11 patients at all post-operative time points. We were able to show that NOVOCART 3D implantation of cartilage defects after acute trauma and osteochondritis dissecans (OCD) led to a significantly increased proportion of graft hypertrophy. No other individual criteria (age, gender, BMI) or defect-associated criteria (concomitant surgery, second-line treatment, defect size, fixation technique) showed any influence on the development of graft hypertrophy. The modified MOCART Score results revealed a significant post-operative improvement within 2 years.

CONCLUSION

The aetiology of cartilage defects appears to have a relevant influence for the development of graft hypertrophy. Patients, who were treated with NOVOCART 3D implants after an acute event (acute trauma or OCD), are especially at risk for developing a graft hypertrophy in the post-operative course of two years.

LEVEL OF EVIDENCE

Case series, Level IV.

Implantation of tissue-engineered cartilage-like tissue for the treatment for full-thickness cartilage defects of the knee

PURPOSE

The purposes of this study were to evaluate early- to midterm clinical results after implantation of tissue-engineered cartilage-like tissue for the treatment for full-thickness cartilage defects of the knee and to identify the factors affecting the final clinical results.

METHODS

Tissue-engineered cartilage-like tissue was prepared by culturing autologous chondrocytes in atelocollagen gel for 3-4 weeks. A total of 73 knees of 72 patients with full-thickness cartilage defects were implanted with this tissue-engineered cartilage-like tissue. The follow-up of these patients for >5 years (range 5-11 years, median 8.0 years) is reported. The patients were evaluated clinically using a rating scale, as well as arthroscopically, biomechanically, and histologically. A modified magnetic resonance observation of cartilage repair tissue (MOCART) system was used to quantify the magnetic resonance imaging (MRI) findings of the lesions. The patient or defect factors influencing the final clinical outcomes were also investigated.

RESULTS

Clinical rating improved significantly after implantation of tissue-engineered cartilage-like tissue. Arthroscopic findings at 2 years after implantation were graded as normal or nearly normal according to the International Cartilage Repair Society (ICRS) scale in 64 of 73 knees (87.7%). Biomechanically, stiffness of the graft almost equalled the surrounding normal cartilage (87.9-102.5%) at 2 years after implantation. Histologically, overall assessment of the repaired tissue by ICRS Visual Assessment Scale II was 70.4 ± 20.8. The average MOCART score was 13.5 ± 11.3 (0-45) preoperatively, 66.6 ± 16.8 (10-90) at 1 year after implantation, 70.4 ± 16.1 (15-90) at 2 years after implantation, and 72.5 ± 17.4 (15-95) at the final follow-up, indicating that MRI results were maintained. Among the factors investigated, only arthroscopic grade of the repaired lesion at 2 years after implantation was significantly correlated with the final clinical scores.

CONCLUSIONS

Implantation of tissue-engineered cartilage-like tissue for the cartilage defects of the knee was effective in short- to midterm post-operatively. This procedure can be proposed as one option for repairing full-thickness cartilage defect of the knee.

LEVEL OF EVIDENCE

IV.

Early resumption of physical activities leads to inferior clinical outcomes after matrix-based autologous chondrocyte implantation in the knee

PURPOSE

Matrix-based autologous chondrocyte implantation is a well-established operation procedure for full cartilage defects. When to resume physical activity after matrix-based autologous chondrocyte implantation is controversial. Our hypothesis was that early resumption of physical activity leads to a worse clinical outcome after matrix-based autologous chondrocyte implantation in the knee two years post-operatively. Physical activity is defined as any kind of impact sport.

METHODS

Forty-four patients with cartilage defects of the knee were treated with matrix-based autologous chondrocyte implantation (Novocart3D). All patients were assessed preoperatively and after a period of 24 months with the University of California Los Angeles (UCLA) Activity score. The return to physical activities or sports after matrix-based autologous chondrocyte implantation was documented. Patients were evaluated using the International Knee Documentation Committee Knee Examination Form and visual analogue scale for pain after 6, 12 and 24 months.

RESULTS

Fifty-five percent showed an unchanged level of physical activity in the UCLA Activity score post-operatively. About 35% showed a lower level and 10% a higher level of physical activity. The average return to physical activities or sports after matrix-based autologous chondrocyte implantation procedure was 10.2 months. Patients with a later return of sports after 12 months showed significantly better clinical results after two years. In particular, patients who started practicing impact sport after 12 months post-operatively showed significantly better results.

CONCLUSION

Resuming physical activity including impact sports without waiting at least 12 months after the operation leads to inferior outcomes up to 24 months after matrix-based autologous chondrocyte implantation.

LEVEL OF EVIDENCE

Level IV.

Autologous chondrocyte implantation and anteromedialization for isolated patellar articular cartilage lesions: 5- to 11-year follow-up

BACKGROUND

Isolated chondral lesions of the patella are particularly challenging to treat, and long-term studies of treated isolated patellar lesions are limited. Previous short-term studies have reported favorable outcomes of autologous chondrocyte implantation (ACI) of the patella and/or trochlea, with a trend toward improvement when anteromedialization (AMZ) of the tibial tubercle was performed with the procedure.

HYPOTHESIS

Autologous chondrocyte implantation with concomitant AMZ for symptomatic isolated patellar lesions provides functional and symptomatic improvement in patients at a minimum 5-year follow-up.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients with failed primary treatment of isolated patellar full-thickness articular cartilage defects and patellofemoral malalignment who were treated with ACI and AMZ of the tibial tubercle at least 5 years prior were contacted for final postoperative outcome scores. Outcome scales including the International Knee Documentation Committee (IKDC), Lysholm, modified Cincinnati Knee Rating System, and 12-item Short Form Health Survey (SF-12) scores were assessed at baseline and final follow-up.

RESULTS

Of 27 eligible patients, 23 (25 knees) were available for assessment at a mean follow-up of 7.6 years (range, 5.1-11.4 years). Significant improvements from baseline to final follow-up were observed in the IKDC score (from 42.5 to 75.7; P < .0001), modified Cincinnati Knee Rating System score (from 3.0 to 7.0; P < .0001), Lysholm score (from 40.2 to 79.3; P < .0001), and SF-12 score (physical component score: from 41.2 to 47.6; P = .002; mental component score: from 48.1 to 60.7; P = .0001). Most patients (83%; 19/23) rated their surgery as good or excellent. The overall reoperation rate was 40% (10/25) largely because of periosteal hypertrophy (33%). One patient failed at 5.9 years postoperatively and underwent patellofemoral arthroplasty.

CONCLUSION

Combined ACI and AMZ resulted in significant improvements in symptoms and function with a low incidence of adverse events in patients with isolated symptomatic patellar chondral defects after a mean follow-up of more than 7 years.

Intra-articular administration of hyaluronic acid increases the volume of the hyaline cartilage regenerated in a large osteochondral defect by implantation of a double-network gel

Implantation of PAMPS/PDMAAm double-network (DN) gel can induce hyaline cartilage regeneration in the osteochondral defect. However, it is a problem that the volume of the regenerated cartilage tissue is gradually reduced at 12 weeks. This study investigated whether intra-articular administration of hyaluronic acid (HA) increases the volume of the cartilage regenerated with the DN gel at 12 weeks. A total of 48 rabbits were used in this study. A cylindrical osteochondral defect created in the bilateral femoral trochlea was treated with DN gel (Group DN) or left without any implantation (Group C). In both Groups, we injected 1.0 mL of HA in the left knee, and 1.0 mL of saline solution in the right knee. Quantitative histological evaluations were performed at 2, 4, and 12 weeks, and PCR analysis was performed at 2 and 4 weeks after surgery. In Group DN, the proteoglycan-rich area was significantly greater in the HA-injected knees than in the saline-injected knees at 12 weeks (P = 0.0247), and expression of type 2 collagen, aggrecan, and Sox9 mRNAs was significantly greater in the HA-injected knees than in the saline-injected knees at 2 weeks (P = 0.0475, P = 0.0257, P = 0.0222, respectively). The intra-articular administration of HA significantly enhanced these gene expression at 2 weeks and significantly increased the volume of the hyaline cartilage regenerated by implantation of a DN gel at 12 weeks. This information is important to develop an additional method to increase the volume of the hyaline cartilage tissue in a potential cartilage regeneration strategy using the DN gel.

Articular cartilage repair: procedures versus products

This review discusses the current perspectives and practices regarding the treatment of articular cartilage injury. Specifically, the authors have delineated and examined articular cartilage repair techniques as either surgical procedures or manufactured products. Although both methodologies are used to treat articular cartilage injury, there are obvious advantages and disadvantages to the application of both, with the literature providing few recommendations on the most suitable regimen for the patient and surgeon. In recent times, cell-based tissue engineering products, predominantly autologous chondrocyte implantation, have been the subject of much research and have become clinically popular. Herein, we review the most used procedures and products in cartilage repair, compare and contrast their outcomes, and evaluate the issues that must be overcome in order to improve patient efficacy in the future.