Primary Autologous Chondrocyte Implantation of the Knee Versus Autologous Chondrocyte Implantation After Failed Marrow Stimulation: A Systematic Review

Therapeutic targets and potential delivery systems of melatonin in osteoarthritis

Osteoarthritis (OA) is a highly prevalent age-related musculoskeletal disorder that typically results in chronic pain and disability. OA is a multifactorial disease, with increased oxidative stress, dysregulated inflammatory response, and impaired matrix metabolism contributing to its onset and progression. The neurohormone melatonin, primarily synthesized by the pineal gland, has emerged as a promising therapeutic agent for OA due to its potential to alleviate inflammation, oxidative stress, and chondrocyte death with minimal adverse effects. The present review provides a comprehensive summary of the current understanding regarding melatonin as a promising pharmaceutical agent for the treatment of OA, along with an exploration of various delivery systems that can be utilized for melatonin administration. These findings may provide novel therapeutic strategies and targets for inhibiting the advancement of OA.

Increased risk of reoperation and failure to attain clinically relevant improvement following autologous chondrocyte implantation of the knee in female patients and individuals with previous surgeries: a time-to-event analysis based on the German cartilage registry (KnorpelRegister DGOU)

PURPOSE

This study aimed to analyze the risk of reoperation following autologous chondrocyte implantation (ACI) of the knee utilizing third-generation ACI products in a time-to-event analysis and report on the associated patient-reported outcome measures (PROM) in case of reoperation.

METHODS

Patients undergoing ACI were included from a longitudinal database. Patient age, sex, body mass index (BMI), number of previous surgeries, lesion localization, lesion size, symptom duration, as well as time and type of reoperation was extracted. A cox proportional-hazards model was applied to investigate the influence of baseline variables on risk of reoperation. Reoperation was defined as any type of subsequent ipsilateral knee surgery, excluding hardware removal. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was utilized to compare PROM between patients with and without reoperation.

RESULTS

A total of 2039 patients were included with 1359 (66.7%) having a minimum follow-up of 24 months. There were overall 243 reoperations (prevalence 17.9%). Minor arthroscopic procedures (n = 96, 39.5%) and revision cartilage repair procedures (n = 78, 32.1%) were the most common reoperations. Nineteen patients (0.9%) reported conversion arthroplasty at 17.7 (10.4) months after ACI. Female sex (HR 1.5, 95% CI [1.2, 2.0], p = 0.002) and the presence of 1-2 previous surgeries (HR 1.5, 95% CI [1.1, 2.0], p = 0.010), or more than 2 previous surgeries (HR 1.9, 95% CI [1.2, 2.9], p = 0.004) were significantly associated with increased risk of reoperation following ACI. Significantly less patients surpassed the minimal clinically important difference (MCID) in the reoperation group at 24 months regarding the KOOS subscores pain (OR 1.6, 95% CI [1.1, 2.2]), quality of life (OR 2.2, 95% CI [1.6, 3.2]), symptoms (OR 2.0 [1.4, 2.9]), and sports (OR 2.0 [1.4, 2.8]).

CONCLUSION

Female patients and individuals with a history of previous surgeries face an elevated risk of requiring reoperation after undergoing ACI, which is associated with failure to attain clinically relevant improvements. A thorough evaluation of the indications for ACI is paramount, particularly when patients have a history of previous surgeries.

LEVEL OF EVIDENCE

Level III.

Sericin nano-gel agglomerates mimicking the pericellular matrix induce the condensation of mesenchymal stem cells and trigger cartilage micro-tissue formation without exogenous stimulation of growth factors in vitro

Mesenchymal stem cells (MSCs) are excellent seed cells for cartilage tissue engineering and regenerative medicine. Though the condensation of MSCs is the first step of their differentiation into chondrocytes in skeletal development, the process is a challenge in cartilage repairing by MSCs. The pericellular matrix (PCM), a distinct region surrounding the chondrocytes, acts as an extracellular linker among cells and forms the microenvironment of chondrocytes. Inspired by this, sericin nano-gel soft-agglomerates were prepared and used as linkers to induce MSCs to assemble into micro-spheres and differentiate into cartilage-like micro-tissues without exogenous stimulation of growth factors. These sericin nano-gel soft-agglomerates are composed of sericin nano-gels prepared by the chelation of metal ions and sericin protein. The MSCs cultured on 2D culture plates self-assembled into cell-microspheres centered by sericin nano-gel agglomerates. The self-assembly progress of MSCs is superior to the traditional centrifugation to achieve MSC condensation due to its facility, friendliness to MSCs and avoidance of the side-effects of growth factors. The analysis of transcriptomic results suggested that sericin nano-gel agglomerates offered a soft mechanical stimulation to MSCs similar to that of the PCM to chondrocytes and triggered some signaling pathways as associated with MSC chondrogenesis. The strategy of utilizing biomaterials to mimic the PCM as a linker and as a mechanical micro-environment and to induce cell aggregation and trigger the differentiation of MSCs can be employed to drive 3D cellular organization and micro-tissue fabrication in vitro. These cartilage micro-masses reported in this study can be potential candidates for cartilage repairing, cellular building blocks for 3D bio-printing and a model for cartilage development and drug screening.

Biological Reconstruction of Localized Full-Thickness Cartilage Defects of the Knee: A Systematic Review of Level 1 Studies with a Minimum Follow-Up of 5 Years

OBJECTIVE

The objective of this study was to evaluate the best available mid- to long-term evidence of surgical procedures for the treatment of localized full-thickness cartilage defects of the knee.

DESIGN

Systematic review using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines of Level 1 randomized clinical trials (RCTs), meta-analyses of RCTs and systematic reviews with a minimum follow-up of 5 years. Data extracted included patient demographics, defect characteristics, clinical and radiological outcomes, as well as treatment failures.

RESULTS

Six RCTs and 3 Level 1 systematic reviews were included. Two RCTs compared microfracture (MFx) to periosteum-covered autologous chondrocyte implantation (ACI-P), 1 to matrix-associated ACI (M-ACI) and 2 to osteochondral autograft transplantation (OAT). One study compared OAT to collagen membrane covered ACI (ACI-C). The 3 Level 1 systematic reviews/meta-analyses assessed the outcome of MFx, OAT, and various ACI methods in RCTs. OAT showed significantly better outcomes compared with MFx. In the 2 RCTs comparing ACI-P and MFx, no significant differences in clinical outcomes were seen, whereas significantly better outcomes were reported for M-ACI versus MFx in 1 study including patients with larger defects (5 cm²), and for ACI-C versus OAT in terms of Cincinnati Score. Higher failure rates were reported for MFx compared with OAT and for OAT compared with ACI-C, while no significant differences in failure rates were observed for ACI-P compared to MFx.

CONCLUSION

Restorative cartilage procedures (ACI-C or M-ACI and OAT) are associated with better long-term clinical outcomes including lower complication and failure rates when compared with reparative techniques (MFx). Among the restorative procedures, OAT seems to be inferior to ACI especially in larger defects after longer follow-up periods.

LEVEL OF EVIDENCE

Level I: Systematic review of Level I studies.

The Most Common Rehabilitation Protocol After Matrix-Assisted Autologous Chondrocyte Implantation Is Immediate Partial Weight-Bearing and Continuous Passive Motion

Purpose

To perform a systematic review of postoperative rehabilitation protocols for third-generation autologous chondrocyte implantation (ACI) of the knee joint.

Methods

A systematic review was performed by searching PubMed, Cochrane Library, and EMBASE to locate randomized controlled trials that described a rehabilitation protocol following third-generation ACI of the knee joint. The search terms used were: "autologous" AND "chondrocyte" AND "randomized". Data extracted from each study included various components of postoperative rehabilitation, such as initial weight-bearing (WB) status and time to full WB, the use of continuous passive motion (CPM), the time to return to sports, and physical therapy (PT) modalities used and the timing of their initiation.

Results

Twenty-five studies (22 Level I, 3 Level II) met inclusion criteria, including a total of 905 patients undergoing treatment with ACI. The average patient age ranged from 29.1 to 54.8 years, and the mean follow-up time ranged from 3 months to 10.0 years. The average lesion size ranged from 1.9 to 5.8 cm², and the most common lesion location was the medial femoral condyle (n = 494). Twenty studies allowed partial WB postoperatively with all studies permitting full WB within 12 weeks. Twenty studies used CPM in their rehabilitation protocols and initiated its use within 24 hours postoperatively. Among 10 studies that reported time to return to sport, 9 (90%) allowed return by 12 months. While most protocols used strength training as well as the inclusion of proprioceptive training, there was disagreement on the timing and inclusion of specific PT modalities used during the rehabilitation process.

Conclusions

Based on the included studies, most rehabilitation protocols for third-generation ACI initiate CPM within 24 hours postoperatively and allow partial WB immediately following surgery with progression to full WB within 12 weeks. There is variation of the PT modalities used as well as the timing of their initiation.

Level of Evidence

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

Low postoperative complication rate with high survival rate and good clinical outcome 9 years after autologous chondrocyte transplantation of the knee joint

PURPOSE

To investigate postoperative complications and associated risk factors for failure following autologous chondrocyte transplantation ("ACT") as well as its long-term survival and clinical function. It was hypothesized that ACT is a safe technique for cartilage repair with a low incidence of postoperative complications and rare rates of revision surgery combined with a high long-term survival and good to excellent clinical outcome in long-term-follow-up.

METHODS

All patients undergoing ACT-Cs of the knee joint between 2006 and 2012 at the author's institution were included in this retrospective study. Concomitant procedures had been performed if necessary. Early postoperative complications, revision surgeries, failure and risk factors for those events were evaluated 6 months after the surgery. Long-term clinical outcome was assessed using the Lysholm Score, the Tegner Score, a 10-grade scale for satisfaction and the Visual Analogue Scale (VAS) at a minimum follow-up of 9 years postoperatively. Long-term survival was calculated using revision surgeries, clinical failures and conversion procedures to create a Kaplan-Meier analysis. A subgroup analysis for different defect locations was performed. 139 patients were included in this study (27% female/ 73%male; age 26.7 [21.7; 35.2] years). The median defect size was 4.0 [3.0; 6.0] cm² (40% medial femoral condyle (MFC), 17% lateral femoral condyle (LFC), 36% patella, 19% trochlea). 97 (70%) of the patients had undergone previous surgery and 84 (60%) underwent concomitant procedures.

RESULTS

Postoperatively, 8% of patients had complications (4% bleeding, 2% arthrofibrosis, 2% infection), 7% of patients needed revision surgery. 12% of patients had a prolonged deficit in ROM, that did not require revision surgery. No significant difference in terms of complications was found between the patellofemoral and femorotibial group. Patients demonstrated good patient reported long-term outcomes 9-15 years after the index surgery (Tegner: 4.7 ± 1.8; VAS: 2.4 ± 2.1; Lysholm: 80 ± 14; satisfaction with operation: 7.3 ± 1.9). Survival rates were 88% at 9 years, 85% at 11 years, and 85% at 13 years after the index procedure. Reasons for failure included debridement of ACT (n = 4; 5%), revision ACT (n = 3, 3%), conversion to total knee arthroplasty (n = 3, 3%) and conversion to High tibial osteotomy (HTO) (n = 1; 1%)).

CONCLUSION

The present study indicates ACT as an effective treatment option for femorotibial- as well as patellofemoral cartilage defects with a high long-term survival and low conversion rate as well as good long-term results regarding knee function and satisfaction. Postoperative complications needing revision surgery are rare. Prolongated deficits of range of motion appear frequently up to six months especially in patellofemoral defects, but can often be successfully addressed by intensified physiotherapy without requiring an arthrolysis.

LEVEL OF EVIDENCE

Level III.

Deconstruction of Knee Cartilage Injury in Athletes Using MR Images Based on Artificial Intelligence Segmentation Algorithm

The knee joint is the second largest joint in the human body, with a wide range of functional activities and strong support for the human body. Moreover, the cartilage of the knee joint is hyaline cartilage, which is relatively brittle, so it is most vulnerable to trauma. In clinical work, the damage of articular cartilage is a disease with a high rate of orthopedic visits. In this paper, all the experimental group cases included in the observation were patients with acute articular cartilage injury or OA diagnosed by knee arthroscopy. All experimental groups and control groups did not have any strenuous exercise one day before MRI (magnetic resonance imaging), and they sat for 30 minutes before the examination. Conventional scanning sagittal FSE-T1WI, FSE-T2WI, FS-FSE-T1WI, FS-FSE-T2WI, FS-PDWI, and coronal FS-PDWI sequence. In the normal control group, after the T2 color map was generated in the workstation, the articular cartilage was divided on the midsagittal plane, and the patellar cartilage and tibial plateau were roughly divided into upper, middle, lower and anterior, middle, and posterior thirds. In order to ensure the maximum comparability of the results, an artificial intelligence segmentation algorithm is used to divide the region of interest equally, and the central part of each partition is selected as much as possible for measurement. The T2 values of the three partitions of each cartilage were measured one by one and averaged. For the comparison results of T2 value of cartilage in the same part: according to patellar cartilage, femoral cartilage, and tibial cartilage, the P values are 0.973, 0.150, and 0.525, respectively. Therefore, early detection and early treatment of articular cartilage injury are of great significance to the performance of athletes' competition level and the extension of sports life.

Third-Generation Autologous Chondrocyte Implantation (Cells Cultured Within Collagen Membrane) Is Superior to Microfracture for Focal Chondral Defects of the Knee Joint: Systematic Review and Meta-analysis

PURPOSE

To systematically review randomized controlled trials to compare clinical outcomes of microfracture (MFx) versus third-generation autologous chondrocyte implantation (ACI) for the treatment of focal chondral defects (FCDs) of the knee joint.

METHODS

A systematic review was performed by searching PubMed, Cochrane Library, and EMBASE to locate randomized controlled trials comparing minimum 2-year clinical outcomes of patients undergoing MFx versus third-generation ACI for FCDs of the knee joint. The search terms used were: "knee" AND "microfracture" AND "autologous chondrocyte" AND "randomized." Patients were evaluated based on treatment failure rates, magnetic resonance imaging, International Cartilage Repair Society scores, and patient-reported outcome scores (Lysholm, Tegner, Knee Injury and Osteoarthritis Outcome Score, modified Cincinnati Knee Rating System, 12-item Short Form Health Survey Physical and Mental, and the EuroQol 5 Dimensions Visual Analog Scale score).

RESULTS

Six studies (5 Level I, 1 Level II) met inclusion criteria, including a total of 238 patients undergoing MFx and 274 undergoing ACI. Two studies had an overlapping cohort of patients and therefore the study with longer follow-up was used in all analyses. The average follow-up among patients ranged from 2.0 years to 6.0 years. Average lesion size ranged from 1.8 cm² to 5.0 cm². Treatment failure ranged from 0% to 1.8% in the ACI group and 2.5% to 8.3% in the MFx group. In 4 studies, ACI patients demonstrated significantly greater improvement in multiple Knee Injury and Osteoarthritis Outcome Score subscores compared with MFx. In 2 studies, patients who received ACI demonstrated significantly greater improvement in the Tegner score compared to MFx, and 1 study showed significantly greater improvement in the Lysholm and ICRS scores for ACI compared with MFx.

CONCLUSIONS

At short-term follow-up, third-generation ACI demonstrates a lower failure rate and greater improvement in patient-reported outcomes compared with MFx for FCDs of the knee joint.

LEVEL OF EVIDENCE

II, systematic review of Levels I-II studies.

Melatonin: A novel candidate for the treatment of osteoarthritis

Osteoarthritis (OA), characterized by cartilage erosion, synovium inflammation, and subchondral bone remodeling, is a common joint degenerative disease worldwide. OA pathogenesis is regulated by multiple predisposing factors, including imbalanced matrix metabolism, aberrant inflammatory response, and excessive oxidative stress. Moreover, melatonin has been implicated in development of several degenerative disorders owing to its potent biological functions. With regards to OA, melatonin reportedly promotes synthesis of cartilage matrix, inhibition of chondrocyte apoptosis, attenuation of inflammatory response, and suppression of matrix degradation by regulating the TGF-β, MAPK, or NF-κB signaling pathways. Notably, melatonin has been associated with amelioration of oxidative damage by restoring the OA-impaired intracellular antioxidant defense system in articular cartilage. Findings from preliminary application of melatonin or melatonin-loaded biomaterials in animal models have affirmed its potential anti-arthritic effects. Herein, we summarize the anti-arthritic effects of melatonin on OA cartilage and demonstrate that melatonin has potential therapeutic efficacy in treating OA.

Improved Outcomes with Arthroscopic Bone Marrow Aspirate Concentrate and Cartilage-Derived Matrix Implantation versus Chondroplasty for the Treatment of Focal Chondral Defects of the Knee Joint: A Retrospective Case Series

Purpose

To compare the outcomes of patients undergoing treatment of focal chondral defects (FCDs) of the knee joint with chondroplasty versus bone marrow aspirate concentrate (BMAC) and cartilage-derived matrix (CDM) implantation.

Methods

A retrospective chart review was performed for patients diagnosed with Outerbridge grade 3-4 FCDs. Patients were included if they were treated arthroscopically with BMAC/CDM implantation or chondroplasty alone between March 2016 and May 2019 and had more than 1-year follow-up. Postoperative outcomes included the visual analog scale (VAS) for pain; University of California, Los Angeles (UCLA) activity scores; Knee Outcome Survey (KOS) Activities of Daily Living (ADL) and Sports subscores; postoperative corticosteroid or hyaluronic acid injections; subsequent surgeries; and conversion to total knee arthroplasty.

Results

A total of 98 patients were identified with a mean follow-up in BMAC/CDM of 24 months (range 13-41 months) and in chondroplasty of 44 months (range 34-55 months). A subanalysis was performed to control for significant differences in age, which yielded 39 patients, ages 40-60 years. Within the subanalysis group, mean VAS scores were significantly lower in the BMAC/CDM group (1.7 vs 4.4; P = .005) and mean UCLA scores were significantly greater (7.1 vs 5.0; P = .002). Mean improvement in VAS and UCLA scores were similar between the BMAC/CDM and chondroplasty groups (–3.7 vs –1.3; P = .71, 1.9 vs 0.1; P = .14, respectively). Mean KOS ADL and Sports subscores were significantly greater among patients in the BMAC/CDM group (87% vs 55%; P = .001, 71% vs 41%; P = .002, respectively). There were no differences in postoperative injections, subsequent surgeries, or conversion to total knee arthroplasty between the BMAC/CDM and chondroplasty groups.

Conclusions

Patients with grade 3-4 FCDs of the knee had improved postoperative outcomes when treated with BMAC/CDM implantation versus chondroplasty alone, as evidenced by a significant improvement in VAS and UCLA scores and significantly greater postoperative KOS ADL, and KOS Sport subscores.

Level of Evidence

IV, therapeutic case series.

Treatment of Large Cartilage Defects in the Knee by Hydrogel-Based Autologous Chondrocyte Implantation: Two-Year Results of a Prospective, Multicenter, Single-Arm Phase III Trial

OBJECTIVE

To evaluate the clinical outcome of a hydrogel-based autologous chondrocyte implantation (ACI) for large articular cartilage defects in the knee joint.

DESIGN

Prospective, multicenter, single-arm, phase III clinical trial. ACI was performed in 100 patients with focal full-thickness cartilage defects ranging from 4 to 12 cm² in size. The primary outcome measure was the responder rate at 2 years using the Knee Injury and Osteoarthritis Outcome Score (KOOS).

RESULTS

Two years after ACI treatment, 93% of patients were KOOS responders having improved by ≥10 points compared with their pre-operative level. The primary endpoint of the study was met and demonstrated that the KOOS response rate is markedly greater than 40% with a lower 95% CI (confidence interval) of 86.1, more than twice the pre-specified no-effect level. KOOS improvement (least squares mean) was 42.0 ± 1.8 points (95% CI between 38.4 and 45.7). Mean changes from baseline were significant in the overall KOOS and in all 5 KOOS subscores from Month 3 (first measurement) to Month 24 (inclusive) (P < 0.0001). The mean MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score after 24 months reached 80.0 points (95% CI: 70.0-90.0 points) and 92.1 points in lesions ≤ 5 cm².

CONCLUSIONS

Overall, hydrogel-based ACI proved to be a valuable treatment option for patients with large cartilage defects in the knee as demonstrated by early, statistically significant, and clinically meaningful improvement up to 2 years follow-up. Parallel to the clinical improvements, MRI analyses suggested increasing maturation, re-organization, and integration of the repair tissue.

TRIAL REGISTRATION

NCT03319797; EudraCT No.: 2016-002817-22.

Effect of Previous Knee Surgery on Clinical Outcome After ACI for Knee Cartilage Defects: A Propensity Score-Matched Study Based on the German Cartilage Registry (KnorpelRegister DGOU)

BACKGROUND

Autologous chondrocyte implantation (ACI) is an established procedure for the treatment of cartilage damage in the knee joint. At present, it is still unclear how previous surgery influences outcome after ACI.

PURPOSE

To evaluate the effect of previous knee surgery related or nonrelated to the treated cartilage defect on clinical outcome after ACI for knee cartilage defects.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

An overall 730 patients with ACI who underwent previous unspecific knee surgery, whether related to the defect being currently treated or not, were identified from a cohort of 5961 patients registered in the German Cartilage Registry. Propensity score matching was used to match these patients to 690 patients with analogous characteristics but without previous surgery. Subsequently, 317 patients with previously failed cartilage treatment at the defect site were identified and compared with a matched collective of 254 patients without previous cartilage treatment. In a subgroup analysis, the type of previous cartilage surgery was additionally investigated. Outcome was evaluated by Knee injury and Osteoarthritis Outcome Score (KOOS), visual analog scale for pain, rate of reintervention, and patient satisfaction up to 36 months. A chi-square test was used to compare categorial variables and an unpaired t test to compare continuous variables.

RESULTS

Patients with previous knee surgery not related to the cartilage defect showed a lower KOOS at 6 months (68.3 vs 70.8; P = .026), while patients with previous cartilage surgery showed significantly lower KOOS values at all follow-up time points when compared with patients without any previous knee or cartilage surgery (all P < .05). A comparison of KOOS values in patients with previous therapy at the cartilage defect with ACI versus bone marrow stimulation did not show any significant differences at any follow-up.

CONCLUSION

Previously failed cartilage treatment at the defect site represents a negative prognostic factor up to 3 years after ACI. However, this influence appears to be independent of the type of previous treatment at the defect site and applies equally to failed bone marrow stimulation as well as previous ACI. In contrast, a negative effect of previous surgery to the knee unrelated to the cartilage defect could not be shown in the 3-year follow-up.

3D Printing for Bone-Cartilage Interface Regeneration

Due to the vasculature defects and/or the avascular nature of cartilage, as well as the complex gradients for bone-cartilage interface regeneration and the layered zonal architecture, self-repair of cartilage and subchondral bone is challenging. Currently, the primary osteochondral defect treatment strategies, including artificial joint replacement and autologous and allogeneic bone graft, are limited by their ability to simply repair, rather than induce regeneration of tissues. Meanwhile, over the past two decades, three-dimension (3D) printing technology has achieved admirable advancements in bone and cartilage reconstruction, providing a new strategy for restoring joint function. The advantages of 3D printing hybrid materials include rapid and accurate molding, as well as personalized therapy. However, certain challenges also exist. For instance, 3D printing technology for osteochondral reconstruction must simulate the histological structure of cartilage and subchondral bone, thus, it is necessary to determine the optimal bioink concentrations to maintain mechanical strength and cell viability, while also identifying biomaterials with dual bioactivities capable of simultaneously regenerating cartilage. The study showed that the regeneration of bone-cartilage interface is crucial for the repair of osteochondral defect. In this review, we focus on the significant progress and application of 3D printing technology for bone-cartilage interface regeneration, while also expounding the potential prospects for 3D printing technology and highlighting some of the most significant challenges currently facing this field.

Cell-based treatment options facilitate regeneration of cartilage, ligaments and meniscus in demanding conditions of the knee by a whole joint approach

PURPOSE

This article provides an update on the current therapeutic options for cell-based regenerative treatment of the knee with a critical review of the present literature including a future perspective on the use of regenerative cell-based approaches. Special emphasis has been given on the requirement of a whole joint approach with treatment of comorbidities with aim of knee cartilage restoration, particularly in demanding conditions like early osteoarthritis.

METHODS

This narrative review evaluates recent clinical data and published research articles on cell-based regenerative treatment options for cartilage and other structures around the knee RESULTS: Cell-based regenerative therapies for cartilage repair have become standard practice for the treatment of focal, traumatic chondral defects of the knee. Specifically, matrix-assisted autologous chondrocyte transplantation (MACT) shows satisfactory long-term results regarding radiological, histological and clinical outcome for treatment of large cartilage defects. Data show that regenerative treatment of the knee requires a whole joint approach by addressing all comorbidities including axis deviation, instability or meniscus pathologies. Further development of novel biomaterials and the discovery of alternative cell sources may facilitate the process of cell-based regenerative therapies for all knee structures becoming the gold standard in the future.

CONCLUSION

Overall, cell-based regenerative cartilage therapy of the knee has shown tremendous development over the last years and has become the standard of care for large and isolated chondral defects. It has shown success in the treatment of traumatic, osteochondral defects but also for degenerative cartilage lesions in the demanding condition of early OA. Future developments and alternative cell sources may help to facilitate cell-based regenerative treatment for all different structures around the knee by a whole joint approach.

LEVEL OF EVIDENCE

IV.

Hydrogel-based autologous chondrocyte implantation leads to subjective improvement levels comparable to scaffold based autologous chondrocyte implantation

PURPOSE

Scaffold-based autologous chondrocyte implantation is a well-established treatment for cartilage defects in the knee joint. Hydrogel-based autologous chondrocyte implantation using an in situ polymerizable biomaterial is a relatively new treatment option for arthroscopic cartilage defects. It is therefore important to determine if there are significant differences in the outcomes. The aim of this study is to compare the outcomes (using subjective parameters) of hydrogel-based autologous chondrocyte implantation (NOVOCART^® Inject) with the outcomes of scaffold based autologous chondrocyte Implantation (NOVOCART^® 3D) using biphasic collagen scaffold.

METHODS

The data of 50 patients, which were paired with 25 patients in each treatment group, was analyzed. The main parameters used for matching were gender, number of defects and localization. Both groups were compared based on Visual Analogue Scale (VAS) and subjective IKDC scores, both of which were examined pre-operatively and after 6, 12 and 24 months.

RESULTS

Significant benefits in both VAS and IKDC scores after 2 years of follow-up in both groups were found. Comparing the groups, the results showed that in the hydrogel-based autologous chondrocyte implantation group, significant changes in IKDC scores are measurable after 6 months, while it takes 12 months until they are seen in the scaffold based autologous chondrocyte group.

CONCLUSION

Hydrogel-based autologous chondrocyte and scaffold based autologous chondrocyte show comparable improvements and significant benefits to the patients' subjective well-being after a 2-year-follow-up.

LEVEL OF EVIDENCE

III.

Repairing Cartilage with Processed Chondrocyte Constructs: A 6-Month Study Using a Porcine Model

OBJECTIVE

Autologous chondrocyte implantation was the first cell-based therapy that used a tissue engineering process to repair cartilage defects. Recently improved approaches and tissue-engineered cell constructs have been developed for growing patient populations. We developed a chondrocyte construct using a collagen gel and sponge scaffold and physicochemical stimuli, implanted with a surgical adhesive. We conducted a proof-of-concept study of these improvements using a cartilage defect model in miniature swine.

DESIGN

We implanted the autologous chondrocyte constructs into full-thickness chondral defects in the femoral condyle, compared those results with empty and acellular scaffold controls, and compared implantation techniques with adhesive alone and with partial adhesive with suture. Two weeks after the creation of the defects and implantation of the cellular or acellular constructs, we arthroscopically confirmed that the implanted constructs remained at the chondral defects. We evaluated the regenerated tissue macro- and microscopically 6 months after the cell constructs were implanted. The tissues were stained with Safranin-O and evaluated using Sellers' histology grading system.

RESULTS

The defects implanted with processed cell constructs and acellular scaffolds were filled with chondrocyte-like round cells and with nearly normal tissue architecture that were significantly greater degree compared to empty defect control. Even with the adhesive alone and with suture alone, the cell construct was composed of the dense cartilaginous matrix that was found in the implantation using both the sutures and the adhesive.

CONCLUSION

Implantation of cell constructs promoted regeneration and integration of articular cartilage at chondral defects in swine by 6 months.