Second-generation autologous chondrocyte transplantation: MRI findings and clinical correlations at a minimum 5-year follow-up

Autologous and Allogeneic Cytotherapies for Large Knee (Osteo)Chondral Defects: Manufacturing Process Benchmarking and Parallel Functional Qualification

Cytotherapies are often necessary for the management of symptomatic large knee (osteo)-chondral defects. While autologous chondrocyte implantation (ACI) has been clinically used for 30 years, allogeneic cells (clinical-grade FE002 primary chondroprogenitors) have been investigated in translational settings (Swiss progenitor cell transplantation program). The aim of this study was to comparatively assess autologous and allogeneic approaches (quality, safety, functional attributes) to cell-based knee chondrotherapies developed for clinical use. Protocol benchmarking from a manufacturing process and control viewpoint enabled us to highlight the respective advantages and risks. Safety data (telomerase and soft agarose colony formation assays, high passage cell senescence) and risk analyses were reported for the allogeneic FE002 cellular active substance in preparation for an autologous to allogeneic clinical protocol transposition. Validation results on autologous bioengineered grafts (autologous chondrocyte-bearing Chondro-Gide scaffolds) confirmed significant chondrogenic induction (COL2 and ACAN upregulation, extracellular matrix synthesis) after 2 weeks of co-culture. Allogeneic grafts (bearing FE002 primary chondroprogenitors) displayed comparable endpoint quality and functionality attributes. Parameters of translational relevance (transport medium, finished product suturability) were validated for the allogeneic protocol. Notably, the process-based benchmarking of both approaches highlighted the key advantages of allogeneic FE002 cell-bearing grafts (reduced cellular variability, enhanced process standardization, rationalized logistical and clinical pathways). Overall, this study built on our robust knowledge and local experience with ACI (long-term safety and efficacy), setting an appropriate standard for further clinical investigations into allogeneic progenitor cell-based orthopedic protocols.

Comparison of Hydrogel-Based Autologous Chondrocyte Implantation Versus Microfracture: A Propensity Score Matched-Pair Analysis

Background

Few studies exist for large defects comparing matrix-associated autologous chondrocyte implantation (M-ACI) with other cartilage repair methods due to the limited availability of suitable comparator treatments.

Purpose

To compare the clinical efficacy of a novel hydrogel-based M-ACI method (NOVOCART Inject plus) versus microfracture (MFx) in patients with knee cartilage defects.

Study Design

Cohort study; Level of evidence, 3.

Methods

Propensity score matched-pair analysis was used to compare the 24-month outcomes between the M-ACI treatment group from a previous single-arm phase 3 study and the MFx control group from another phase 3 study. Patients were matched based on preoperative Knee injury and Osteoarthritis Outcomes Score (KOOS), symptom duration, previous knee surgeries, age, and sex, resulting in 144 patients in the matched-pair set (72 patients per group). The primary endpoint was the change in least-squares means (ΔLSmeans) for the KOOS from baseline to the 24-month assessment.

Results

Defect sizes in the M-ACI group were significantly larger than in the MFx group (6.4 versus 3.7 cm2). Other differences included defect location (no patellar or tibial defects in the MFx group), number of defects (33.3% with 2 defects in the M-ACI group versus 9.7% in the MFx group), and defect cause (more patients with degenerative lesions in the M-ACI group). The M-ACI group had higher posttreatment KOOS (M-ACI versus MFX: 81.8 ± 16.8 versus 73.0 ± 20.6 points) and KOOS ΔLSmeans from baseline to 24 months posttreatment (M-ACI versus MFX: 36.9 versus 26.9 points). Treatment contrasts in KOOS ΔLSmeans from baseline indicated statistical significance in favor of M-ACI from 3 to 24 months posttreatment (P = .0026). Significant and clinically meaningful differences in favor of M-ACI at 24 months were also found regarding International Knee Documentation Committee (IKDC) score ΔLSmeans from baseline (37.8 versus 30.4 points; P = .0334), KOOS responder rates at 24 months (≥10-point improvement from baseline; 94.4% versus 65.3%; P < .0001), IKDC responder rates at 24 months (>20.5-point improvement from baseline; 83.3% versus 61.1%, P = .0126) and MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score in a subgroup of patients (LS means, 86.9 versus 69.1; P = .0096).

Conclusion

In this exploratory analysis, M-ACI using an in situ crosslinked hydrogel demonstrated superior clinical and structural (MOCART) 24-month outcomes compared with MFx in patients with knee cartilage defects.

An accelerated 6-week return to full weight bearing after matrix-induced autologous chondrocyte implantation results in good clinical outcomes to 5 years post-surgery

PURPOSE

To investigate the mid-term outcomes of an accelerated return to full weight bearing (WB) after matrix-induced autologous chondrocyte implantation (MACI).

METHODS

This randomized study allocated 35 patients (37 knees) to a 6 week (n = 18) or 8 week (n = 19) return to full WB after MACI. Patients were evaluated pre-operatively and at 1, 2 and minimum 5 years (range 5.5-7 years), using the KOOS, SF-36, visual analogue pain scale, 6-min walk test and active knee range of motion (ROM). Peak isokinetic knee extensor and flexor strength was assessed, with limb symmetry indices (LSIs) calculated. Magnetic resonance imaging (MRI) was undertaken to evaluate the repair tissue, and an MRI composite score was calculated.

RESULTS

While no group differences (n.s.) were observed, significant improvement was observed for all patient-reported outcome measures (p < 0.05), 6-min walk distance (p = 0.040), active knee flexion (p = 0.002) and extension (p < 0.0001) ROM, and the LSI for peak knee extensor strength (p < 0.0001). At final review, 87.5% (6 weeks) and 82.4% (8 weeks) of patients were satisfied overall. A non-significant decline (n.s.) was observed for the MRI composite score from 1-year post-surgery to final review, with no significant MRI-based differences (n.s.) between groups. At final review, two grafts (6-week n = 1, 8-week n = 1) demonstrated MRI-based graft failure, while an additional patient had progressed toward knee arthroplasty (8.1% failure rate at minimum 5 years).

CONCLUSIONS

The 6-week return to full WB after MACI provided comparable clinical and MRI-based outcomes beyond 5 years post-surgery, without jeopardizing the graft. This 6-week WB protocol is faster than those previously proposed and studied.

LEVEL OF EVIDENCE

II.

Long-term Prospective Clinical and Magnetic Resonance Imaging-Based Evaluation of Matrix-Induced Autologous Chondrocyte Implantation

BACKGROUND

Matrix-induced autologous chondrocyte implantation (MACI) has demonstrated encouraging midterm clinical outcomes, although published studies presenting longer-term clinical and radiological outcomes, across varied tibiofemoral and patellofemoral graft locations, are scarce.

PURPOSE

To present the clinical and radiological outcomes a minimum of 10 years after surgery in a consecutive series of patients who underwent MACI in the tibiofemoral or patellofemoral knee joint. Secondly, to investigate any association between outcomes and patient characteristics, graft parameters, and injury and surgery history.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Overall, 87 patients (99 grafts: 57 medial femoral condyle, 24 lateral femoral condyle, 11 trochlea, 7 patella) were prospectively evaluated clinically and with magnetic resonance imaging (MRI) before surgery and at 2, 5, and minimum 10 years after MACI (mean, 13.1 years; range, 10.5-16 years). Patients were evaluated with a range of patient-reported outcome measures (PROMs), including the Knee injury and Osteoarthritis Outcome Score (KOOS) and patient satisfaction. The 6-minute walk test, active knee range of motion, and peak isokinetic knee extensor and flexor strength were assessed. Limb symmetry indices (LSIs) were calculated for strength measures. MRI was undertaken to evaluate the repair tissue, and an MRI composite score was calculated.

RESULTS

All PROMs significantly improved (P < .05) over the pre- to postoperative period. Apart from KOOS Sport (P = .018) and the LSI for peak isokinetic knee extensor strength (P = .005), which significantly improved, no significant change (P > .05) was observed from 2 years after surgery to final follow-up (range, 10.5-16 years) in all other PROMs, 6-minute walk distance, active knee range of motion, and the LSI for peak isokinetic knee flexor strength. At final follow-up, while the mean LSIs for peak isokinetic knee flexor and extensor strength were 96.9% and 95.7%, respectively, 74.7% of patients were satisfied with their ability to participate in sports, and 88.5% were satisfied overall. A nonsignificant decline was observed for tissue infill (P = .211) and the MRI composite score (P = .099) from 2 years to final review. At final MRI review, 9 grafts (9.1%) had failed. While no significant association (P > .05) was observed between clinical or MRI-based outcomes and patient demographics (age, body weight, body mass index), defect size, or the duration of preoperative symptoms, the number of previous surgical procedures was significantly and negatively associated with KOOS Symptoms (P = .015), KOOS Sport (P = .011), and the degree of tissue infill (P = .045).

CONCLUSION

MACI provided high levels of satisfaction and adequate graft survivorship as visualized on MRI at 10.5 to 16 years after surgery.

Cartilage T2 Relaxation Times and Subchondral Trabecular Bone Parameters Predict Morphological Outcome After Matrix-Associated Autologous Chondrocyte Implantation With Autologous Bone Grafting

BACKGROUND

Quantitative magnetic resonance (MR) imaging techniques are established for evaluation of cartilage composition and trabecular bone microstructure at the knee. It remains unclear whether quantitative MR parameters predict the midterm morphological outcome after matrix-associated chondrocyte implantation (MACI) with autologous bone grafting (ABG).

PURPOSE

To assess longitudinal changes and associations of the biochemical composition of cartilage repair tissue, the subchondral bone architecture, and morphological knee joint abnormalities on 3-T MR imaging after MACI with ABG at the knee.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Knees of 18 patients (28.7 ± 8.4 years [mean ± SD]; 5 women) were examined preoperatively and 3, 6, 12, and 24 months after MACI and ABG using 3-T MR imaging. Cartilage composition was assessed using T₂ relaxation time measurements. Subchondral bone microstructure was quantified using a 3-dimensional phase-cycled balanced steady-state free precision sequence. Trabecular bone parameters were calculated using a dual threshold algorithm (apparent bone fraction, apparent trabecular number, and apparent trabecular separation). Morphological abnormalities were assessed using the MOCART (magnetic resonace observation of cartilage repair tissue) score, the WORMS (Whole-Organ Magnetic Resonance Imaging Score), and the CROAKS (Cartilage Repair Osteoarthritis Knee Score). Clinical symptoms were assessed using the Tegner activity and Lysholm knee scores. Statistical analyses were performed by using multiple linear regression analysis.

RESULTS

Total WORMS (P = .02) and MOCART (P = .001) scores significantly improved over 24 months after MACI. Clinical symptoms were significantly associated with the presence of bone marrow edema pattern abnormalities 24 months after surgery (P = .035). Overall there was a good to excellent radiological outcome found after 24 months (MOCART score, 88.8 ± 10.1). Cartilage repair T₂ values significantly decreased between 12 and 24 months after MACI (P = .009). Lower global T₂ values after 3 months were significantly associated with better MOCART scores after 24 months (P = .04). Moreover, trabecular bone parameters after 3 months were significantly associated with the total WORMS after 24 months (apparent bone fraction, P = .048; apparent trabecular number, P = .013; apparent trabecular separation, P = .013).

CONCLUSION

After MACI with ABG, early postoperative quantitative assessment of biochemical composition of cartilage and microstructure of subchondral bone may predict the outcome after 24 months. The perioperative global joint cartilage matrix quality is essential for proper proliferation of the repair tissue, reflected by MOCART scores. The subchondral bone quality of the ABG site is essential for proper maturation of the cartilage repair tissue, reflected by cartilage T₂ values.

Autologous collagen-induced chondrogenesis versus microfracture for chondral defects of the knee: Surgical technique and 2-year comparison outcome study

Objective

Osteochondral lesions of the knee affect patients from all age groups with arthroscopic microfracture being the current gold standard of treatment of such lesions. Autologous collagen-induced chondrogenesis (ACIC) is a novel procedure that has recently been gaining popularity. This study aims to compare the 6 and 24 month post-operative outcomes between patients undergoing microfracture only and microfracture with ACIC.

Methods

Patients from both groups were assessed pre-operatively, at 6 and 24 months post-operatively for functional outcomes using SF-36 and IKDC scoring (International Knee Documentation Committee Subjective Knee Form).

Results

Both groups showed improved SF-36 and IKDC scores at 6 and 24 months, however patients who underwent ACIC showed better SF-36 mental component and IKDC scores 24 months after surgery.

Conclusion

This demonstrates that ACIC is an effective, single-stage, joint-preserving procedure which is comparable, if not better, in treating chondral defects.

Minimum 10-Year Clinical and Radiological Outcomes of a Randomized Controlled Trial Evaluating 2 Different Approaches to Full Weightbearing After Matrix-Induced Autologous Chondrocyte Implantation

BACKGROUND

Longer term outcomes after matrix-induced autologous chondrocyte implantation (MACI) are lacking, while early postoperative weightbearing (WB) management has traditionally been conservative.

PURPOSE

To investigate the longer term clinical and radiological outcomes after an 8-week (vs 12-week) WB protocol after MACI.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A randomized study design allocated 70 patients to an 8- (n = 34) or 12-week (n = 36) approach to full WB after MACI of the medial or lateral femoral condyle. Patients were evaluated preoperatively; at 3, 12, and 24 months after surgery; and at 5 and 10 years after surgery. At 10 years (range, 10.5-11.5 years), 60 patients (85.7%; 8 weeks: n = 29; 12 weeks: n = 31) were available for review. Clinical outcomes included patient-reported outcomes, maximal isokinetic knee extensor and flexor strength, and functional hop capacity. High-resolution magnetic resonance imaging (MRI) was undertaken to assess the quality and quantity of repair tissue per the MOCART (magnetic resonance observation of cartilage repair tissue) system. A combined MRI composite score was also evaluated.

RESULTS

Clinical and MRI-based scores for the full cohort significantly improved (P < .05) over the 10-year period. Apart from the Tegner activity score, which improved (P = .041), as well as tissue structure (P = .030), which deteriorated, there were no further statistically significant changes (P > .05) from 5 to 10 years. There were no 10-year differences between the 2 WB rehabilitation groups. At 10 years, 81.5% and 82.8% of patients in the 8- and 12-week groups, respectively, demonstrated good-excellent tissue infill. Graft failure was observed on MRI at 10 years in 7 patients overall, which included 4 located on 10-year MRI (8 weeks: n = 1; 12 weeks: n = 3) and a further 3 patients (8 weeks: n = 1; 12 weeks: n = 2) not included in the current analysis who proceeded to total knee arthroplasty. At 10 years, 93.3% of patients were satisfied with MACI for relieving their pain, with 83.3% satisfied with their ability to participate in sport.

CONCLUSION

MACI provided high satisfaction levels and tissue durability beyond 10 years. The outcomes of this randomized trial demonstrate a safe 8-week WB rehabilitation protocol without jeopardizing longer term outcomes.

T2-relaxation time of cartilage repair tissue is associated with bone remodeling after spongiosa-augmented matrix-associated autologous chondrocyte implantation

OBJECTIVE

To investigate whether T2 relaxation time measurements of cartilage repair tissue and structural changes of the knee joint are associated with subchondral bone architecture after spongiosa-augmented matrix-associated autologous chondrocyte implantation (MACI).

DESIGN

Both knees of 25 patients (25.5 ± 7.8y; 10 women) were examined preoperatively and 2.7 years after unilateral spongiosa-augmented MACI with 3T magnetic resonance (MR) imaging. Cartilage composition was assessed using T2 relaxation time measurements, subchondral trabecular bone microstructure was quantified using a 3D phase-cycled balanced steady state free-precision sequence. Structural knee joint changes were assessed using the modified Whole-Organ Magnetic Resonance Imaging Score (WORMS). The Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score was used for the postoperative description of the area that underwent MACI. Correlations were assessed using Spearman's rank correlation coefficients.

RESULTS

Hypertrophy of the cartilage repair tissue was found in 2 of 25 patients, both after a MACI procedure at the patella, 21 patients showed congruent filling. In subchondral bone of the cartilage repair compartment, apparent trabecular thickness was significantly higher in compartments with elevated cartilage T2 (n = 17; 0.37 ± 0.05 mm) compared to those showing no difference in cartilage T2 compared to the same compartment in the contralateral knee (n = 8; 0.27 ± 0.05 mm; P = 0.042). Significant correlations were found between the overall progression of WORMS and the ipsilateral vs contralateral ratio of average trabecular thickness (r = 0.48, P = 0.031) and bone fraction (r = 0.57, P = 0.007).

CONCLUSIONS

After spongiosa-augmented MACI, T2 values of cartilage repair tissue and structural knee joint changes correlated with the quality of the underlying trabecular bone.

Featured Article: In vitro development of personalized cartilage microtissues uncovers an individualized differentiation capacity of human chondrocytes

Personalized features in the treatment of knee injuries and articular replacement therapies play an important role in modern life with increasing demand. Therefore, cell-based therapeutic approaches for the regeneration of traumatic defects of cartilage tissue were developed. However, great variations in the quality of repair tissue or therapeutic outcome were observed. The aim of the study was to capture and visualize individual differentiation capacities of chondrocytes derived from different donors with regard to a possible personal regeneration capacity using a cell-based therapy. The redifferentiation potential of monolayer cultured cells was analyzed in a scaffold-free three-dimensional tissue model. Furthermore, stimulating options using cartilage maturation factors such as L-ascorbic acid and transforming growth factor beta 2 (TGF-β₂) on this process were of special interest. Cells and tissues were analyzed via histological and immunohistochemical methods. Gene expression was measured by quantitative real-time polymerase chain reaction. In monolayer culture, cells from all donors showed an almost identical differentiation profile. In contrast, the differentiation state of cartilage-like three-dimensional microtissues revealed clear differences with respect to individual donors. Analyses at the protein and mRNA levels showed high variations regarding cartilage-typical matrix components (e.g. proteoglycans, collagen type II) and intracellular proteins (e.g. S100). Interestingly, only donor chondrocytes with a basic tendency to re-differentiate in a three-dimensional environment were able to increase this tissue-specific maturation when exposed to L-ascorbic acid and/or TGF-β2. Our approach revealed clear-cut possibilities for classification of individual donors into responders or non-responders. On the basis of these results an in vitro platform could be designed to discriminate responders from non-responders. This in vitro three-dimensional test system may be a suitable basis to establish a "personalized diagnostic tool" with the opportunity to assess the capacity of expanded chondrocytes to respond to an autologous cell-based therapy. Impact statement A challenge in cell-based cartilage regeneration therapies is the identification of a "personalized diagnostic tool" to predict the chondrogenic potency of cells from patients who are going to be treated with autologous cells. Comparing the phenotype of isolated chondrocytes from different donors in vitro revealed an individual cartilage-specific differentiation capacity. These personalized features are not detectable in vitro until the monolayer cells have the possibility to rearrange in 3D tissues. Cells from articular cartilage in monolayer culture may not be a suitable basis to discriminate responders from non-responders with respect to a personalized cell-based therapy to treat cartilage defects. A more physiological 3D (micro-)environment enable the cells to present their individual differentiation capacity. The here described microtissue model might be the basis for an in vitro platform to predict the therapeutic outcome of autologous cell-based cartilage repair and/or a suitable tool to identify early biomarkers to classify the patients.

Applications of Tissue Engineering in Joint Arthroplasty: Current Concepts Update

Research in tissue engineering has undoubtedly achieved significant milestones in recent years. Although it is being applied in several disciplines, tissue engineering's application is particularly advanced in orthopedic surgery and in degenerative joint diseases. The literature is full of remarkable findings and trials using tissue engineering in articular cartilage disease. With the vast and expanding knowledge, and with the variety of techniques available at hand, the authors aimed to review the current concepts and advances in the use of cell sources in articular cartilage tissue engineering.

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.

Two-Year Outcomes of a Randomized Trial Investigating a 6-Week Return to Full Weightbearing After Matrix-Induced Autologous Chondrocyte Implantation

BACKGROUND

Matrix-induced autologous chondrocyte implantation (MACI) has demonstrated encouraging outcomes in treating patients with knee cartilage defects. Postoperatively, the time required to attain full weightbearing (WB) remains conservative.

HYPOTHESIS

We hypothesized that patients would have no significant clinical or radiological differences or graft complications after an 8-week or 6-week return to full WB after MACI.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 37 knees (n = 35 patients) were randomly allocated to either an 8-week return to full WB that we considered current best practice based on the existing literature (CR group; n = 19 knees) or an accelerated 6-week WB approach (AR group; n = 18 knees). Patients were evaluated preoperatively and at 1, 2, 3, 6, 12, and 24 months after surgery, using the Knee Injury and Osteoarthritis Outcome Score, 36-Item Short Form Health Survey, visual analog pain scale, 6-minute walk test, and active knee range of motion. Isokinetic dynamometry was used to assess peak knee extension and flexion strength and limb symmetry indices (LSIs) between the operated and nonoperated limbs. Magnetic resonance imaging (MRI) was undertaken to evaluate the quality and quantity of repair tissue as well as to calculate an MRI composite score.

RESULTS

Significant improvements ( P < .05) were observed in all subjective scores, active knee flexion and extension, 6-minute capacity, peak knee extensor torque in the operated limb, and knee extensor LSI, although no group differences existed. Although knee flexor LSIs were above 100% for both groups at 12 and 24 months after surgery, LSIs for knee extensor torque at 24 months were 93.7% and 87.5% for the AR and CR groups, respectively. The MRI composite score and pertinent graft parameters significantly improved over time ( P < .05), with some superior in the AR group at 24 months. All patients in the AR group (100%) demonstrated good to excellent infill at 24 months, compared with 83% of patients in the CR group. Two cases of graft failure were observed, both in the CR group. At 24 months, 83% of patients in the CR group and 88% in the AR group were satisfied with the results of their MACI surgery.

CONCLUSION

Patients in the AR group who reduced the length of time spent ambulating on crutches produced comparable outcomes up to 24 months, without compromising graft integrity.

A Prospective Clinical and Radiological Evaluation at 5 Years After Arthroscopic Matrix-Induced Autologous Chondrocyte Implantation

BACKGROUND

While midterm outcomes after matrix-induced autologous chondrocyte implantation (MACI) are encouraging, the procedure permits an arthroscopic approach that may reduce the morbidity of arthrotomy and permit accelerated rehabilitation.

HYPOTHESIS

A significant improvement in clinical and radiological outcomes after arthroscopic MACI will exist through to 5 years after surgery.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

We prospectively evaluated the first 31 patients (15 male, 16 female) who underwent MACI via arthroscopic surgery to address symptomatic tibiofemoral chondral lesions. MACI was followed by a structured rehabilitation program in all patients. Clinical scores were administered preoperatively and at 3 and 6 months as well as 1, 2, and 5 years after surgery. These included the Knee injury and Osteoarthritis Outcome Score (KOOS), Lysholm knee scale (LKS), Tegner activity scale (TAS), visual analog scale for pain, Short Form-36 Health Survey (SF-36), active knee motion, and 6-minute walk test. Isokinetic dynamometry was used to assess peak knee extension and flexion strength and limb symmetry indices (LSIs) between the operated and nonoperated limbs. High-resolution magnetic resonance imaging (MRI) was performed at 3 months and at 1, 2, and 5 years postoperatively to evaluate graft repair as well as calculate the MRI composite score.

RESULTS

There was a significant improvement ( P < .05) in all KOOS subscale scores, LKS and TAS scores, the SF-36 physical component score, pain frequency and severity, active knee flexion and extension, and 6-minute walk distance. Isokinetic knee extension strength significantly improved, and all knee extension and flexion LSIs were above 90% (apart from peak knee extension strength at 1 year). At 5 years, 93% of patients were satisfied with MACI to relieve their pain, 90% were satisfied with improving their ability to undertake daily activities, and 80% were satisfied with the improvement in participating in sport. Graft infill ( P = .033) and the MRI composite score ( P = .028) significantly improved over time, with 90% of patients demonstrating good to excellent tissue infill at 5 years. There were 2 graft failures at 5 years after surgery.

CONCLUSION

The arthroscopically performed MACI technique demonstrated good clinical and radiological outcomes up to 5 years, with high levels of patient satisfaction.

A novel aragonite-based scaffold for osteochondral regeneration: early experience on human implants and technical developments

INTRODUCTION

Chondral and osteochondral lesions represent a debilitating disease. Untreated lesions remain a risk factor for more extensive joint damage. The objective of this clinical study is to evaluate safety and early results of an aragonite-based scaffold used for osteochondral unit repair, by analysing both clinical outcome and MRI results, as well as the benefits of the procedure optimization through novel tapered shaped implants.

METHODS

A crystalline aragonite bi-phasic scaffold was implanted in patients affected by focal chondral-osteochondral knee lesions of the condyle and trochlea. Twenty-one patients (17 men, 4 women with a mean age of 31.0 ± 8.6 years) without severe OA received tapered shaped implants for the treatment of 2.5 ±1.7 cm² sized defects. The control group consisted of 76 patients selected according to the same criteria from a database of patients who previously underwent implantation of cylindrical-shaped implants. The clinical outcome of all patients was evaluated with the IKDC subjective score, the Lysholm score, and all 5 KOOS subscales administered preoperatively and at 6 and 12 months after surgery, while MRI evaluation was performed at the 12 month follow-up.

RESULTS

A statistically significant improvement in all clinical scores was documented both in the tapered implants and the cylindrical group. No difference could be detected in the comparison between the improvement obtained with the two implant types, neither in the clinical nor in imaging evaluations. A difference could be detected instead in terms of revision rate, which was lower in the tapered implant group with no implant removal - 0% vs 8/76-10.5% failures in the cylindrical implants.

CONCLUSIONS

This study highlighted both safety and potential of a novel aragonite-based scaffold for the treatment of chondral and osteochondral lesions in humans. A tapered shape relative to the cylindrical shaped implant design, improved the scaffold's safety profile. Tapered scaffolds maintain the clinical improvement observed in cylindrical implants while reducing the postoperative risk of revision surgery. This aragonite-based implant was associated with a significant clinical improvement at the 12 month follow-up. Moreover, MRI findings revealed graft integration with good bone and cartilage formation.

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.

Cartilage failures. Systematic literature review, critical survey analysis, and definition

PURPOSE

While midterm results of matrix-assisted autologous chondrocyte transplantation (MACT) are now available, less attention has been paid to the evaluation of failures of this surgical approach. Aim of this study was to analyse how "failures" are generally defined in cartilage surgery, in order to understand how the survival rate may change according to different definitions of failure.

METHODS

A systematic review on MACT in the knee was conducted to report failure rates as well as different failure definitions in the available literature. Afterwards, we analysed the survival curve at 8.5-year follow-up of a survey of 193 patients treated with MACT. Using different definitions to identify failures, we compared how the survival rate changed according to the different definitions of failure.

RESULTS

The systematic review on 93 papers showed that the average failure rate reported on 3,289 patients was 5.2 % at a mean 34 months of follow-up. However, 41 studies (44.1 %) did not even consider this aspect, and failures were variously defined, thus generating confusing data that make a meta-analysis or a study comparison meaningless. The failure analysis of the MACT survey showed that the survival curve changed significantly depending on the definition applied; in fact, the failure rate ranged from 3.6 to 33.7 %. According to a critical literature and survey analysis, we proposed a combined surgical- and improvement-based definition which led to a failure rate of 25.9 % at midterm/long-term follow-up.

CONCLUSION

Nowadays, failure definitions of cartilage treatments differ in scientific articles, thus generating confusion and heterogeneous data even when applied to the same cohort of patients. While the literature analysis shows a low number of failures, this study demonstrated that if properly addressed with a comprehensive definition, the real failure rate of cartilage surgical procedures in the knee is higher than previously reported. Recognizing failures would give a better understanding and a more realistic prognosis to patients and physicians seeking treatment for cartilage lesions.

LEVEL OF EVIDENCE

IV.

Matrix-induced autologous mesenchymal stem cell implantation versus matrix-induced autologous chondrocyte implantation in the treatment of chondral defects of the knee: a 2-year randomized study

BACKGROUND

Cell-based strategies that combine in vitro- expanded autologous chondrocytes with matrix scaffolds are currently preferred for full-thickness cartilage lesions of the knee ≥2 cm(2). Although this approach is reasonable, continuing advances in the field of cartilage repair will further expand the options available to improve outcomes.

HYPOTHESIS/PURPOSE

In the present clinical study, we compared the outcomes of matrix-induced autologous mesenchymal stem cell implantation (m-AMI) with matrix-induced autologous chondrocyte implantation (m-ACI) for the treatment of isolated chondral defects of the knee.

STUDY DESIGN

Prospective, single-site, randomized, single-blind pilot study.

METHODS

Fourteen patients with isolated full-thickness chondral lesions of the knee >2 cm(2) were randomized into two treatment groups: m-AMI and m-ACI. Outcomes were assessed pre-operatively and 3, 6, 12 and 24 months post-operatively.

RESULTS

Clinical evaluations revealed that improvement from pre-operation to 24 months post-operation occurred in both groups (p < 0.05). At all follow-up intervals, m-AMI demonstrated significantly better functional outcomes (motion deficit and straight leg raise strength) than did m-ACI (p < 0.05). At all follow-up intervals, m-AMI demonstrated significantly better subjective sub-scale scores for pain, symptoms, activities of daily living and sport and recreation of the knee injury and osteoarthritis outcome score (KOOS) than did m-ACI (p < 0.05). Additionally, m-AMI demonstrated significantly better (p < 0.05) scores than m-ACI for the quality of life sub-scale of the KOOS and visual analog scale (VAS) severity at the 6-month follow-up. The Tegner activity score and VAS frequency were not significantly different between the two groups. Graft failure was not observed on magnetic resonance imaging at the 24-month follow-up. m-AMI and m-ACI demonstrated very good-to-excellent and good-to-very good infill, respectively, with no adverse effects from the implant, regardless of the treatment.

CONCLUSION

For the treatment of isolated full-thickness chondral lesion of the knee, m-AMI can be used effectively and may potentially accelerate recovery. A larger patient cohort and follow-up supported by histological analyses are necessary to determine long-term outcomes.

Fabrication of polymeric biomaterials: a strategy for tissue engineering and medical devices

Fabrication of biomaterials scaffolds using various methods and techniques is discussed, utilising biocompatible, biodegradable and stimuli-responsive polymers and their composites. This review covers the lithography and printing techniques, self-organisation and self-assembly methods for 3D structural scaffolds generation, and smart hydrogels, for tissue regeneration and medical devices.

Clinical and radiological long-term outcomes after matrix-induced autologous chondrocyte transplantation: a prospective follow-up at a minimum of 10 years

BACKGROUND

It is unclear whether matrix-associated autologous chondrocyte transplantation (MACT) results in objective and subjective clinical improvements at 10 years after surgery.

HYPOTHESIS

Matrix-associated autologous chondrocyte transplantation will result in clinical and radiological improvements in patients with symptomatic, traumatic chondral defects of the knee joint.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 16 patients with chondral defects of the knee were treated with MACT between November 2000 and April 2002 and evaluated for up to 10 years after the intervention. The International Knee Documentation Committee (IKDC) form, Knee Injury and Osteoarthritis Outcome Score (KOOS), Tegner activity score, Brittberg score, Noyes sports activity rating scale, and visual analog scale (VAS) for pain as well as 3-T magnetic resonance imaging (MRI) using the magnetic resonance observation of cartilage repair tissue (MOCART) score and functional evaluation by the limb symmetry index (LSI) formed the basis of this study. The Friedman test and the Wilcoxon signed-rank test were performed for a comparison between all time points and 2 separate time points, respectively. If significant differences were revealed, a Bonferroni adjustment to the α level was applied so that P values <.007 (<.05/7) were regarded as significant in the paired comparisons.

RESULTS

Significant improvements (P < .05) from baseline to 120 months postoperatively were observed for the IKDC score (mean, 44.1 ± 26.9 to 59.0 ± 27.4), Noyes sports activity rating score (mean, 37.7 ± 30.1 to 62.1 ± 31.3), and KOOS Quality of Life and Pain subscores, whereas no statistically significant improvement was detected for the Brittberg score, Tegner activity score, or VAS score. After 5 years, a slight downward tendency of all clinical scores was evident. After 10 years, the mean MOCART score was 70.4 ± 16.1. Complete filling of the defect was observed in 73.9% of cases, and osteophytes were present in 78.3%. In 65.2% of the cases, a subchondral bone edema <1 cm was visible, whereas in 21.7% of the cases, a subchondral bone edema >1 cm was seen. The mean LSI for the single-legged hop test was 95.6% ± 16.2% and for the triple hop test for distance was 91.3% ± 12.2%. The mean VAS score for self-perceived stability was 60.2 ± 3.5 (range, 0-9.5) for the injured and 60.7 ± 3.8 (range, 0-10) for the uninjured leg. No adhesions or effusions were seen regarding the clinical and radiological outcomes.

CONCLUSION

The significantly improved results on 3 outcome measures after 10 years suggest that MACT represents a suitable option in the treatment of local cartilage defects in the knee.

Functional imaging in OA: role of imaging in the evaluation of tissue biomechanics

Functional imaging refers broadly to the visualization of organ or tissue physiology using medical image modalities. In load-bearing tissues of the body, including articular cartilage lining the bony ends of joints, changes in strain, stress, and material properties occur in osteoarthritis (OA), providing an opportunity to probe tissue function through the progression of the disease. Here, biomechanical measures in cartilage and related joint tissues are discussed as key imaging biomarkers in the evaluation of OA. Emphasis will be placed on the (1) potential of radiography, ultrasound, and magnetic resonance imaging to assess early tissue pathomechanics in OA, (2) relative utility of kinematic, structural, morphological, and biomechanical measures as functional imaging biomarkers, and (3) improved diagnostic specificity through the combination of multiple imaging biomarkers with unique contrasts, including elastography and quantitative assessments of tissue biochemistry. In comparison to other modalities, magnetic resonance imaging provides an extensive range of functional measures at the tissue level, with conventional and emerging techniques available to potentially to assess the spectrum of preclinical to advance OA.

Correlation Between Clinical and Radiological Outcomes After Matrix-Induced Autologous Chondrocyte Implantation in the Femoral Condyles

BACKGROUND

Matrix-induced autologous chondrocyte implantation (MACI) is an established technique for the repair of knee chondral defects, although the correlation between clinical and radiological outcomes after surgery is poorly understood.

PURPOSE

To determine the correlation between clinical and radiological outcomes throughout the postoperative timeline to 5 years after MACI.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 3.

METHODS

This retrospective study was undertaken in 83 patients (53 male, 30 female) with complete clinical and radiological follow-up at 1, 2, and 5 years after MACI. The mean age of patients was 38.9 years (range, 13-62 years), with a mean body mass index (BMI) of 26.6 kg/m(2) (range, 16.8-34.8 kg/m(2)), mean defect size of 3.3 cm(2) (range, 1-9 cm(2)), and mean preoperative duration of symptoms of 9.2 years (range, 1-46 years). Patients indicated for MACI in this follow-up were 13 to 65 years of age, although they were excluded if they had a BMI >35 kg/m(2), had undergone prior extensive meniscectomy, or had ongoing progressive inflammatory arthritis. Patients were assessed clinically using the Knee Injury and Osteoarthritis Outcome Score (KOOS). Magnetic resonance imaging (MRI) was used to evaluate the graft using a 1.5-T or 3-T clinical scanner; the MRI assessment included 8 parameters of graft repair (infill, signal intensity, border integration, surface contour, structure, subchondral lamina, subchondral bone, and effusion) based on the magnetic resonance observation of cartilage repair tissue (MOCART) score as well as an MRI composite score. The degree of an association between the MRI parameters and the KOOS subscales at each postoperative time point was assessed with the Spearman correlation coefficient (SCC), and significance was determined at P < .05. Ethics approval was obtained from the appropriate hospital and university Human Research Ethics Committees, and informed consent was gathered from all patients.

RESULTS

The only MRI parameter displaying consistent evidence of an association with the KOOS subscales was effusion, with a pattern of increasing strength of correlations over time and statistically significant associations at 5 years with KOOS-Pain (SCC, 0.25; P = .020), KOOS-Activities of Daily Living (SCC, 0.26; P = .018), and KOOS-Sport (SCC, 0.32; P = .003). Apart from a significant correlation between subchondral lamina and KOOS-Sport at 1 year (SCC, 0.27; P = .016), no further significant findings were observed.

CONCLUSION

Apart from some consistent evidence of an association between the KOOS and effusion, this analysis demonstrated a limited correlative capacity between clinical and radiological outcomes up to 5 years after surgery.

Is the clinical outcome after cartilage treatment affected by subchondral bone edema?

PURPOSE

Subchondral bone edema is a common finding after cartilage treatment, but its interpretation is still debated. The aim of this study is to analyse the presence of edema after matrix-assisted autologous chondrocyte transplantation (MACT) for knee cartilage lesions at different follow-up times and its correlation with the clinical outcome.

METHODS

Two hundred and forty-eight magnetic resonance imagings (MRIs) of patients treated with a hyaluronic acid-based MACT for lesions of the knee articular surface were considered. The MRIs belonged to 116 patients (mean age at surgery 28.6 ± 10.3 years, average defect size 2.4 ± 1.0 cm(2)), 57 affected by degenerative cartilage lesions, 27 traumatic and 32 were osteochondritis dissecans (OCD). MRI follow-up was performed from 6 to 108 months after treatment. Other than its presence or absence, the subchondral bone edema was evaluated using a 3-level grading considering extension and hyperintensity, and with the WORMS score edema classification. The IKDC subjective score was collected at the time of every MRI.

RESULTS

An analysis of the entire MRI group showed that edema is not constantly present through the follow-up, but presents a particular and well-defined trend. Edema was present within the first 2 years and was then markedly reduced or disappeared at 2 and 3 years (p = 0.044). Afterwards the level of edema increased again (p < 0.0005) and remained steadily present at medium/long-term follow-up. Patellar lesions presented significantly lower edema (p = 0.012), whereas OCD lesions presented more edema at all follow-up (p = 0.002) and a different trend, with an increasing level of edema over time. No correlation was found between edema and clinical outcome.

CONCLUSIONS

Edema after MACT is present during the first phases of cartilage maturation up to 2 years of follow-up, and then tends to disappear. However, after a few years, it tends to reappear. Less edema was found in the patella, whereas more edema was found in the OCD, where subchondral bone is primarily involved. Interestingly, the presence of edema was not correlated with a poorer clinical outcome. Whether this might be a prognostic factor at longer follow-up remains to be determined, but our results give some indication on what to expect on both MRI edema and clinical outcome after MACT.

LEVEL OF EVIDENCE

Case series, Level IV.

Treatment of Full-Thickness Chondral Defects With Hyalograft C in the Knee: Long-term Results

BACKGROUND

Matrix-associated autologous chondrocyte transplantation (MACT) has become an established articular cartilage repair technique. It provides good short-term and midterm results; however, long-term results are lacking.

PURPOSE

To prospectively assess the clinical outcome after MACT in the knee to report long-term results.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Fifty-three subjects (females/males, 22/31; mean age, 32 ± 12 years) were treated between 2000 and 2006 with a hyaluronan-based MACT product and were followed prospectively. The mean body mass index (BMI) was 24.5 ± 3.8 kg/m(2) and the mean defect size was 4.4 ± 1.9 cm(2). Fifty patients had single defects and 3 had multiple defects (41 medial femoral condyle, 6 lateral femoral condyle, 2 patella, 1 tibia). Two patients had 2 defects (medial femoral condyle [MFC]/lateral femoral condyle and tibial/MFC), and in 1 case, multiple defects on the MFC were treated. The patients were stratified into 23 "simple," 22 "complex," and 8 "salvage" cases. Instability or malalignment was treated before or at the time of graft implantation. For 6 patients with small defects (<2 cm(2)), microfracturing was used as first-line treatment before MACT. Clinical assessment was performed once a year with the subjective and objective International Knee Documentation Committee (IKDC) scores, Lysholm score, and a modified Cincinnati Knee Rating System.

RESULTS

The mean follow-up time was 9.07 ± 2.9 years (range, 5-12 years). Treatment failure occurred in 12 of 53 cases (22.6%) an average of 2.99 ± 1.40 years after surgery. There was 1 failure (4.3%) among the simple cases, 4 failures (18.2%) in complex cases, and 7 failures (87.5%) in salvage cases. Statistically significant increases were observed in all scores at all time points compared with presurgery levels (P < .05). The subjective IKDC score improved from median 40.4 preoperatively to 74.7 at 10-year follow-up (n = 13 patients; P < .05).

CONCLUSION

MACT is an excellent surgical therapy for full-thickness cartilage defects of the knee, with good long-term results for simple defects. However, it should not be used in salvage cases.

Autologous osteochondral transplantation for the treatment of knee lesions: results and limitations at two years' follow-up

PURPOSE

Focal chondral and osteochondral knee lesions are a common condition, particularly hard to treat, and often involve young active patients with high expectations in terms of symptomatic relief and return to sports. Autologous osteochondral transplantation allows the defect area to be restored with hyaline cartilage. The aim of this study is to analyse whether it represents a safe and effective treatment option for small-medium-sized knee chondral and osteochondral lesions in a young and active population.

METHODS

Thirty-one patients (18 men, 13 women; mean age 32 ± ten; mean BMI 24 ± 3) affected by focal knee chondral and osteochondral lesions were enrolled and treated with autologous osteochondral transplantation. They were prospectively followed-up for 24 months with the IKDC-subjective, IKDC-objective, and Tegner scores. Adverse events and failures were also reported, as well as the Bandi score to detect symptoms from the donor area.

RESULTS

A significant increase was reported in all the clinical scores adopted. In particular, the IKDC-subjective score increased from a basal value of 40.3 ± 16.2 to 62.6 ± 18.0 at the 12 months' evaluation, with a further significant increase up to 71.6 ± 20.5 at the final 24 months' follow-up (p < 0.0005). A positive trend was also found by analysing the IKDC-objective score. The Tegner score revealed a significant improvement from a basal value of 2.2 ± 1.8 to 3.7 ± 1.5 at the final evaluation (p = 0.003), although it was not possible to regain the same pre-injury sports activity level of 5.0 ± 2.2. Two failures were reported. The Bandi score revealed patients complaining of mild and moderate symptoms, not correlated to the lesion size. The presence of symptoms ascribable to the donor area was significantly correlated with a lower clinical outcome.

CONCLUSIONS

Autologous osteochondral transplantation proved to be, at short-term evaluation, a suitable option to treat small-medium sized chondral and osteochondral lesions. However, clinical improvement is slow and a significant percentage of patients develop symptoms attributable to the donor area, thus reducing the overall benefit of this procedure.

Implantation of matrix-induced autologous chondrocyte (MACI ®) grafts using carbon dioxide insufflation arthroscopy

PURPOSE

The purpose of this study was to determine the safety of a new arthroscopic Matrix-induced autologous chondrocyte implant (MACI) technique with carbon dioxide insufflation utilized to improve visualization during the dry phase of the scaffold implant.

METHODS

Between 2004 and 2007, thirty patients were treated for symptomatic focal chondral lesions of the medial femoral condyle. All patients were monitored during surgery for gas embolism signs and symptoms and were evaluated preoperatively and at a median follow-up of 70.5 months (range 48-93 months) using the KOOS subjective evaluation score, the Lysholm function score, the Tegner activity scale for the knee, and the IKDC objective score.

RESULTS

No cases of intraoperative or postoperative symptoms or signs related to gas embolism or persistent subcutaneous emphysema were registered. Each subscale of the KOOS subjective score improved from preoperative to follow-up. The median Lysholm score was 50 (range 15-66) at baseline and 87.5 (range 54-100) at follow-up (p < 0.05). The median Tegner score was 2 (range 1-4) at baseline to 5 (range 2-7) at follow-up (p < 0.05).

CONCLUSIONS

No complications registered, and the satisfactory clinical results achieved in this series suggest that carbon dioxide insufflation during arthroscopic MACI is a safe and accessible option to improve visualization during the dry phase of the scaffold implant on medial femoral condyles.

Influence of cell differentiation and IL-1β expression on clinical outcomes after matrix-associated chondrocyte transplantation

BACKGROUND

Several patient- and defect-specific factors influencing clinical outcomes after matrix-associated chondrocyte transplantation (MACT) have been identified, including the patient's age, location of the defect, or duration of symptoms before surgery. Little is known, however, about the influence of cell-specific characteristics on clinical results after transplantation.

PURPOSE

The aim of the present study was to investigate the influence of cell differentiation and interleukin-1 β (IL-1β) expression on clinical outcomes up to 5 years after MACT.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty-seven patients who underwent MACT of the tibiofemoral joint area of the knee were included in this study. Clinical assessments were performed preoperatively as well as 6, 12, 24, and 60 months after transplantation by using the following scores: the Knee injury and Osteoarthritis Outcome Score (KOOS), the International Knee Documentation Committee (IKDC) Subjective Knee Form, the Noyes sports activity rating scale, the Brittberg clinical score, and a visual analog scale (VAS) for pain. The quality of repair tissue was assessed by magnetic resonance imaging using the magnetic resonance observation of cartilage repair tissue (MOCART) score at 1 and 5 years. Cell differentiation (defined as collagen type II:type I expression ratio), aggrecan, and IL-1β expression were determined by real-time polymerase chain reaction in transplant residuals and were correlated with clinical outcomes.

RESULTS

The largest improvements in clinical scores were found during the first year. Two years postoperatively, a stable improvement was reached until 5 years after transplantation, with a mean IKDC score of 34.4 ± 8.6 preoperatively to 77.9 ± 16 after 24 months (P < .001). Cell differentiation showed a significant positive correlation with nearly all clinical scores at different time points, especially after 12 months (P < .05). IL-1β expression negatively influenced clinical outcomes at 24 months (Brittberg score) and 60 months (Brittberg and VAS scores) after surgery (P < .05). No correlation was found between the MOCART score and clinical outcomes or gene expression.

CONCLUSION

Our data demonstrate that cell differentiation and IL-1β expression influence clinical outcomes up to 5 years after MACT.

Clinical results and MRI evolution of a nano-composite multilayered biomaterial for osteochondral regeneration at 5 years

BACKGROUND

Several cartilage lesions involve the subchondral bone, and there is a need for biphasic scaffolds to treat the entire osteochondral unit to reproduce the different biological and functional requirements and guide the growth of the 2 tissues.

PURPOSE

To evaluate the results of a cell-free collagen-hydroxyapatite osteochondral scaffold at midterm, and to use magnetic resonance imaging (MRI) analysis to document the imaging evolution of the tissue regeneration process through 5 years of follow-up.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty-seven patients (9 women, 18 men; mean age, 34.9 ± 10.2 years) treated for knee chondral or osteochondral lesions (size, 1.5-6 cm(2)) were followed for 2 and 5 years and were clinically evaluated using the International Knee Documentation Committee (IKDC) and Tegner scores. An MRI evaluation was performed at both follow-ups in 23 lesions, and the magnetic resonance observation of cartilage repair tissue (MOCART) score and specific subchondral bone parameters (bone regeneration, bone signal quality, osteophytes or upcoming bone front, sclerotic areas, and edema) were analyzed.

RESULTS

A statistically significant improvement in all clinical scores was observed from the initial evaluation to the 2- and 5-year follow-ups, and the results were stable over time. The mean IKDC subjective score improved from 40.0 ± 15.0 to 76.5 ± 14.5 (2-year follow-up) and 77.1 ± 18.0 (5-year follow-up) and the mean Tegner score from 1.6 ± 1.1 to 4.0 ± 1.8 (2-year follow-up) and 4.1 ± 1.9 (5-year follow-up). The MRI evaluation showed a significant improvement in both the MOCART score and subchondral bone status from 2 to 5 years. At 5 years, complete filling of the cartilage was shown in 78.3% of the lesions, complete integration of the graft was detected in 69.6% of cases, the repair tissue surface was intact in 60.9%, and the structure of the repair tissue was homogeneous in 60.9% of the cases. No correlation was found between MRI findings and clinical outcome.

CONCLUSION

This osteochondral scaffold was used for the treatment of chondral and osteochondral knee defects with a single-step procedure. The study results highlighted the safety and potential of this procedure, which offered a good clinical outcome with stable results at midterm follow-up. Although the MRI findings improved over time, some abnormalities persisted, but no correlation was found between the imaging and clinical results.

Osteochondral scaffold reconstruction for complex knee lesions: a comparative evaluation

BACKGROUND

The primary aim of the present study is to evaluate the results obtained in challenging knee lesions with the implant of an osteochondral scaffold and concomitant treatment of all comorbidities. The secondary aim is to compare the results obtained with those found when a chondral scaffold was applied.

MATERIALS AND METHODS

Patients affected by complex lesions of the knee articular surface were included. "Complex cases" were defined according to the following criteria: previous clinical history of intra-articular fracture, lesion located at the tibial plateau, concurrent knee axial realignment procedure, concurrent meniscal scaffold or allograft implantation, and multiple articular surface lesions treated. Thirty-three patients were treated with the implantation of an osteochondral scaffold. The results of a homogeneous group of 23 patients previously treated and prospectively evaluated after implantation of a chondral scaffold were analyzed and compared.

RESULTS

IKDC subjective score improved significantly from pre-operative (40.4±14.1) to 12months' follow-up (69.6±17.0; p<0.0005) with a further improvement at the final evaluation at 24months (75.5±15.0; p=0.038). The same positive trend was confirmed by the VAS and Tegner scores. At final follow-up the group treated with the osteochondral scaffold presented a better subjective IKDC score with respect to the group treated with the chondral scaffold (p=0.034).

CONCLUSIONS

A regenerative procedure to address the entire osteochondral unit, together with the treatment of all comorbidities, might offer good results also in complex cases otherwise doomed to non-biological resurfacing.

LEVEL OF EVIDENCE III

Comparative study.

A comparison of the responsiveness of 4 commonly used patient-reported outcome instruments at 5 years after matrix-induced autologous chondrocyte implantation

BACKGROUND

Patient-reported outcome (PRO) instruments are employed to assess outcomes after matrix-induced autologous chondrocyte implantation (MACI), although the PRO most responsive to change after surgery remains unknown.

PURPOSE

To compare the responsiveness of 4 commonly used PRO instruments at 5 years after MACI.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

The Knee Injury and Osteoarthritis Outcome Score (KOOS), the Lysholm score, the Tegner activity scale, and the 36-item Short Form Health Survey (SF-36) were administered to 104 patients before and at 5 years after MACI knee surgery. The Self-administered Patient Satisfaction Scale was employed at 5 years to investigate each patient's overall level of satisfaction as well as satisfaction with relieving pain and improving the ability to perform daily activities, partake in recreational activities, and participate in sport. The effect size (ES) and standardized response mean (SRM) were used to compare PRO responsiveness. A receiver operating characteristic (ROC) curve analysis was performed to evaluate the extent to which PRO changes were associated with satisfaction. The minimal clinically important difference (MCID) according to the criterion of patient satisfaction was identified as the PRO instrument change score maximizing classification accuracy.

RESULTS

The most responsive PRO measures were the KOOS sport/recreation (ES, 1.63; SRM, 1.43) and quality of life (QOL) (ES, 1.37; SRM, 1.18) subscales. The least responsive were the SF-36 mental component summary (MCS) (ES, 0.38; SRM, 0.40) and the Tegner activity scale (ES, 0.91; SRM, 0.59). Of the 104 patients, 54 (51.9%) reported being "very satisfied," 38 (36.5%) "somewhat satisfied," 8 (7.7%) "somewhat dissatisfied," and 4 (3.9%) "very dissatisfied." A ROC curve analysis was performed using "very satisfied" as the responder criterion. The strongest association was between the change in KOOS sport/recreation with satisfaction in improving the ability to perform recreational activities (area under the curve, 0.756; 95% confidence interval, 0.663-0.849), and the change score maximizing prediction accuracy (MCID) was 40 (sensitivity, 69%; specificity, 76%).

CONCLUSION

The KOOS sport/recreation and QOL subscales were the most responsive PRO measures and were most predictive of satisfaction. This information will provide a guide as to the improvements required in pertinent PRO measures to produce a satisfied patient, while allowing researchers to better structure trials in these patients using the most relevant PRO instruments.

Is magnetic resonance imaging reliable in predicting clinical outcome after articular cartilage repair of the knee? A systematic review and meta-analysis

BACKGROUND

While MRI can provide a detailed morphological evaluation after articular cartilage repair, its additional value in determining clinical outcome has yet to be determined.

PURPOSE

To evaluate the correlation between MRI and clinical outcome after cartilage repair and to identify parameters that are most important in determining clinical outcome.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A systematic search was performed in Embase, MEDLINE, and the Cochrane Collaboration. Articles were screened for relevance and appraised for quality. Guidelines in the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) Statement were used. Chi-square tests were performed to find variables that could determine correlation between clinical and radiological parameters.

RESULTS

A total of 32 articles (total number of patients, 1019) were included. A majority (81%) were case series or cohort studies that used similar standardized MRI techniques. The mean Coleman score was 63 (range, 42-96). For the majority of MRI parameters, limited or no correlation was found. Nine studies (28%) found a correlation between clinical outcome and the composite magnetic resonance observation of cartilage repair tissue (MOCART) or Henderson score and 7 (22%) with defect fill. In 5 studies, a weak to moderate correlation was found between clinical outcome and the T2 index (mean Pearson coefficient r = .53).

CONCLUSION

Strong evidence to determine whether morphological MRI is reliable in predicting clinical outcome after cartilage repair is lacking. Future research aiming specifically at clinical sensitivity of advanced morphological and biochemical MRI techniques after articular cartilage repair could be of great importance to the field.

Matrix assisted autologous chondrocyte transplantation for cartilage treatment: A systematic review

OBJECTIVES

Matrix-assisted autologous chondrocyte transplantation (MACT) has been developed and applied in the clinical practice in the last decade to overcome most of the disadvantages of the first generation procedures. The purpose of this systematic review is to document and analyse the available literature on the results of MACT in the treatment of chondral and osteochondral lesions of the knee.

METHODS

ALL STUDIES PUBLISHED IN ENGLISH ADDRESSING MACT PROCEDURES WERE IDENTIFIED, INCLUDING THOSE THAT FULFILLED THE FOLLOWING CRITERIA: 1) level I-IV evidence, 2) measures of functional or clinical outcome, 3) outcome related to cartilage lesions of the knee cartilage.

RESULTS

The literature analysis showed a progressively increasing number of articles per year. A total of 51 articles were selected: three randomised studies, ten comparative studies, 33 case series and five case reports. Several scaffolds have been developed and studied, with good results reported at short to medium follow-up.

CONCLUSIONS

MACT procedures are a therapeutic option for the treatment of chondral lesions that can offer a positive outcome over time for specific patient categories, but high-level studies are lacking. Systematic long-term evaluation of these techniques and randomised controlled trials are necessary to confirm the potential of this treatment approach, especially when comparing against less ambitious traditional treatments.

Imaging biomarker with T1ρ and T2 mappings in osteoarthritis - in vivo human articular cartilage study

INTRODUCTION

Osteoarthritis (OA) of the knee is a common and disabling disease worldwide. Its prevalence is increasing in view of the aging population. Changes in collagen content, its orientation and GAG content in the articular cartilage with age are the major features in knee osteoarthritis. These changes in collagen and GAG contents show no manifestation in plain radiography and conventional magnetic resonance imaging (MRI). Nevertheless, early diagnosis of the knee osteoarthritis is of paramount importance clinically in view of the evolution of putative interventions in its early stage. The aim of this project is to identify the relationships between the two imaging biomarkers (i.e. T1ρ and T2 mappings) and the GAG concentration in living human symptomatic cartilage.

METHODOLOGY

28 patients with clinical diagnosis of knee osteoarthritis were enrolled. 7 males and 16 females were recruited and their mean age was 68.1 (ranges from 53 to 84). Conventional PD sequence, T1ρ and T2 mappings were performed for each subject within 1 week before total knee arthroplasty. Articular cartilage from the lateral tibial plateau was harvested and the GAG content in cartilage was determined by using dimethylmethylene blue method. T1ρ mean and T2 values were calculated and correlate with GAG concentration statistically.

RESULTS

The mean value T1ρ was 40.3±13.5ms, ranging from 15.3 to 69.3ms and the mean value T2 was 31.0±10.5ms, ranging from 16.1 to 46.9ms. The mean value of GAG content was 80.1±33.3mg, ranging from 24.9 to 166.0mg while the mean value of GAG concentration was 267.4±165.9mg/cm(3), ranging from 91.3 to 760.5mg/cm(3). T2 values were inversely correlated with GAG concentration with R(2)=0.375, p=0.001 while T1ρ values were also inversely correlated with GAG concentration with R(2)=0.200, p=0.025.

CONCLUSION

This in vivo study confirmed that T1ρ and T2 values correlate with the GAG concentration in living human knee cartilages which corroborate with the previous works. The later (T2 values) is found more reliable in our study and less controversial in literatures. We postulate that T2 values can serve as a non-invasive imaging biomarker in the progress of knee osteoarthritis in terms of both disease diagnosis and treatment response monitoring.

Advances in the Surgical Management of Articular Cartilage Defects: Autologous Chondrocyte Implantation Techniques in the Pipeline

OBJECTIVE

The purpose of this review is to gain insight into the latest methods of articular cartilage implantation (ACI) and to detail where they are in the Food and Drug Administration approval and regulatory process.

DESIGN

A PubMed search was performed using the phrase "Autologous Chondrocyte Implantation" alone and with the words second generation and third generation. Additionally, clinicaltrials.gov was searched for the names of the seven specific procedures and the parent company websites were referenced.

RESULTS

Two-Stage Techniques: BioCart II uses a FGF2v1 culture and a fibrinogen, thrombin matrix, whereas Hyalograft-C uses a Hyaff 11 matrix. MACI uses a collagen I/III matrix. Cartipatch consists of an agarose-alginate hydrogel. Neocart uses a high-pressure bioreactor for culturing with a type I collagen matrix. ChondroCelect makes use of a gene expression analysis to predict chondrocyte proliferation and has demonstrated significant clinical improvement, but failed to show superiority to microfracture in a phase III trial. One Step Technique: CAIS is an ACI procedure where harvested cartilage is minced and implanted into a matrix for defect filling.

CONCLUSION

As full thickness defects in articular cartilage continue to pose a challenge to treat, new methods of repair are being researched. Later generation ACI has been developed to address the prevalence of fibrocartilage with microfracture and the complications associated with the periosteal flap of first generation ACI such as periosteal hypertrophy. The procedures and products reviewed here represent advances in tissue engineering, scaffolds and autologous chondrocyte culturing that may hold promise in our quest to alter the natural history of symptomatic chondral disease.

Scaffold-based repair for cartilage healing: a systematic review and technical note

PURPOSE

The aim of this systematic review was to address the treatment of chondral and osteochondral knee lesions through the use of scaffolds, by showing surgical options and results of this scaffold-based repair approach for the healing of the articular surface.

METHODS

All studies published in English addressing cartilage scaffold-based treatment were identified, including those that fulfilled the following criteria: (1) Levels I to IV evidence addressing the outlined areas of interest, (2) measures of functional or clinical outcome, (3) knee cartilage lesions, and (4) minimum of 2 years of follow-up.

RESULTS

The analysis showed a progressively increasing number of articles per year from 1995 to February 2012. The number of selected articles was 51, with 40 focusing on 2-step procedures and 11 focusing on 1-step procedures. The evaluation of evidence level showed 3 randomized studies, 10 comparative studies, 33 case series, and 5 case reports.

CONCLUSIONS

Regenerative scaffold-based procedures are emerging as a therapeutic option for the treatment of chondral lesions, but well-designed studies are lacking. Systematic long-term evaluation of these techniques and randomized studies are necessary to confirm the potential of this treatment approach, especially compared with the available traditional treatments. Different 1-step scaffold-based strategies are emerging to simplify the procedure and reduce costs.

LEVEL OF EVIDENCE

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

Generation of Scaffold Free 3-D Cartilage-Like Microtissues from Human Chondrocytes

Since our society is characterized by an increasing age of its people on the one hand and a high number of persons dealing with sports on the other hand, the number of patients suffering from traumatic defects or osteoarthritis is growing. In combination with the articular cartilage specific limited capacity to regenerate, a need for suitable therapies is obvious. Thereby, cell-based therapies are of major interest. This type of clinical intervention was introduced to patients at the beginning of the 1990s. During the last years, a technological shift from simple cell suspensions to more complex 3D structures was performed. In order to optimize the scaffold free generation of cartilage, such as microtissues from human chondrocytes, the authors examine the influence of a static or spinner flask culture with respect to differentiation and architecture of the engineered microtissues. Additionally, the impact of the soluble factors TGF-ß2 and ascorbic acid on this process are investigated. The results demonstrate a positive impact of TGF-ß2 and ascorbic acid supplementation with respect to general Type II Collagen and proteoglycan expression for both the static and spinner flask culture.

Treatment of cartilage lesions: what works and why?

Cartilage injuries have a high incidence and a high impact on society. In an attempt to fulfill patients' expectations and successfully treat this pathology, various techniques have been developed over the years. Treatments proposed for cartilage lesions are described with their rationale and indications, ranging from conservative measures to surgical approaches, reparative or regenerative. Among the numerous and heterogeneous procedures proposed over time to treat cartilage defects none has clearly proven to lead to a hyaline articular surface nor to offer better clinical results. Regenerative procedures have been introduced as ambitious techniques that aim to overcome the limitations of the more traditional reparative approaches and restore the articular surface with a hyaline-like tissue; improvement in tissue engineering with new scaffolds as well as new regenerative options involving growth factors or MSCs are currently being investigated as promising solutions to further improve the treatment of cartilage lesions. However, the current literature findings are not conclusive. Randomized controlled trials are necessary to evaluate new regenerative approaches, to show clearly advantages and disadvantages with respect to the more traditional procedures, besides their potential, limits, and indications to improve the treatment of patients affected by chondral and osteochondral lesions. Since clear and commonly accepted treatment algorithms are not available in the literature, the massively increasing number of controversial results may be confusing for the orthopaedic surgeon who has to choose the proper management of patients with cartilage lesions. Thus, the results obtained through the study of the authors' 20 years' experience in cartilage treatment were analyzed to give some indications on the potential and limits of different treatment approaches available in clinical practice.

An ovine in vitro model for chondrocyte-based scaffold-assisted cartilage grafts

Background

Scaffold-assisted autologous chondrocyte implantation is an effective clinical procedure for cartilage repair. From the regulatory point of view, the ovine model is one of the suggested large animal models for pre-clinical studies. The aim of our study was to evaluate the in vitro re-differentiation capacity of expanded ovine chondrocytes in biomechanically characterized polyglycolic acid (PGA)/fibrin biomaterials for scaffold-assisted cartilage repair.

Methods

Ovine chondrocytes harvested from adult articular cartilage were expanded in monolayer and re-assembled three-dimensionally in PGA-fibrin scaffolds. De- and re-differentiation of ovine chondrocytes in PGA-fibrin scaffolds was assessed by histological and immuno-histochemical staining as well as by real-time gene expression analysis of typical cartilage marker molecules and the matrix-remodelling enzymes matrix metalloproteinases (MMP) -1, -2 and −13 as well as their inhibitors. PGA scaffolds characteristics including degradation and stiffness were analysed by electron microscopy and biomechanical testing.

Results

Histological, immuno-histochemical and gene expression analysis showed that dedifferentiated chondrocytes re-differentiate in PGA-fibrin scaffolds and form a cartilaginous matrix. Re-differentiation was accompanied by the induction of type II collagen and aggrecan, while MMP expression decreased in prolonged tissue culture. Electron microscopy and biomechanical tests revealed that the non-woven PGA scaffold shows a textile structure with high tensile strength of 3.6 N/mm² and a stiffness of up to 0.44 N/mm², when combined with gel-like fibrin.

Conclusion

These data suggest that PGA-fibrin is suited as a mechanically stable support structure for scaffold-assisted chondrocyte grafts, initiating chondrogenic re-differentiation of expanded chondrocytes.

Clinical and radiological outcomes 5 years after matrix-induced autologous chondrocyte implantation in patients with symptomatic, traumatic chondral defects

BACKGROUND

To date, few studies have been published reporting the 5-year follow-up of clinical and radiological outcomes for chondral defects treated with matrix-induced autologous chondrocyte implantation (MACI).

HYPOTHESIS

A significant improvement in clinical and radiological outcomes after treatment of symptomatic, traumatic chondral defects of the knee with the MACI implant will be maintained up to 5 years after surgery.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A prospective evaluation of the MACI procedure was performed in 21 patients with chondral defects of the knee. After the MACI procedure, patients were clinically assessed with the Knee injury and Osteoarthritis Outcome Score (KOOS), the Tegner-Lysholm score, the International Knee Documentation Committee (IKDC) Subjective Knee Form, and the modified Cincinnati score at years 1, 2, and 5. The quality of repair tissue was assessed by magnetic resonance imaging using the magnetic resonance observation of cartilage repair tissue (MOCART) score at months 3 and 6 and years 1, 2, and 5.

RESULTS

Significant improvements (P < .05) were observed for all 5 KOOS subcategories at year 1 and were maintained through year 5 in 90.5% of patients (19/21). Treatment failure occurred in only 9.5% of patients (2/21). Significant improvements (P < .05) from baseline to year 5 were also observed for the IKDC score (30.1 to 74.3), the modified Cincinnati score (38.1 to 79.6), and the Tegner-Lysholm activity score (1.8 to 4.3). Similarly, the MOCART score significantly improved (P < .001) from baseline to year 5 (52.9 to 75.8). After 5 years, complete filling (83%) and integration (82%) of the graft were seen in the majority of patients. Signs of subchondral bone edema were still present in 47% of patients at 5 years. No product-specific adverse events were reported over the 5-year follow-up period.

CONCLUSION

Patients treated with a MACI implant demonstrated significant clinical improvement and good quality repair tissue 5 years after surgery. The MACI procedure was shown to be a safe and effective treatment for symptomatic, traumatic chondral knee defects in this study.

New trends for knee cartilage regeneration: from cell-free scaffolds to mesenchymal stem cells

In the last decade, huge steps forward have been made in the field of cartilage regeneration. The most recent trend for treating chondral/osteochondral lesions is based on the application of smart biomaterials that could lead to "in situ" regeneration of not only cartilage, but also subchondral bone, preferably through a single step procedure to reduce the costs and the morbidity for the patient. This innovative approach is currently under investigation as several "scaffolds" have been proposed in clinical practice, with or without the aid of cells, with the opportunity, in the second case, of bypassing the strict limits imposed by cell manipulation regulations. Furthermore, the fascinating potential of mesenchymal stem cells has recently opened new paths of research to discover how and whether these powerful entities can really contribute to tissue regeneration. The first clinical trials have been published but further high quality research is needed to understand their mechanisms of action, their limits, and their clinical efficacy.

Regenerative medicine in rheumatic disease-progress in tissue engineering

Joint destruction occurs in both osteoarthritis and rheumatoid arthritis. Even in the era of biologic agents, this destruction can be delayed but not averted. As cartilage has limited ability to self-regenerate, joint arthroplasty is required. Here, we outline current tissue engineering procedures (including autologous chondrocyte implantation and in situ mesenchymal stem cell recruitment) that are routinely applied for the regenerative treatment of injured or early osteoarthritic cartilage. Potential future regenerative therapies, including administration of multipotent or pluripotent stem cells, are also discussed. In the future, cell-free, material-based (for cartilage lesions) or cell-free, factor-based (for osteoarthritic cartilage) therapies to facilitate the recruitment of repair cells and improve cartilage metabolism are likely to become more important. Moreover, delivery of anti-inflammatory factors or immunomodulatory cells could be a regenerative treatment option for rheumatoid arthritis. Tissue engineering faces a crucial phase to translate products into clinical routine and the regulatory framework for cell-based products in particular is an important issue.

Isokinetic knee extensor strength deficit following matrix-induced autologous chondrocyte implantation

BACKGROUND

Autologous chondrocyte implantation has become an established technique for addressing knee cartilage defects. Despite reported improvement in pain and regeneration of hyaline-like repair tissue, little has been reported on the recovery of knee strength.

METHODS

Knee strength assessment was undertaken in 60 patients at 5 years following autologous chondrocyte implantation. Using an isokinetic dynamometer, and during isokinetic knee extension and flexion angular velocities of 60°, 90° and 120°/s, the peak torque, torque at 45° of knee flexion and hamstrings/quadriceps ratio was obtained, in both the operated and non-operated limbs. Pain at the time of assessment was obtained. Independent sample t-tests were used to assess differences in the operated and non-operated sides.

FINDINGS

There were no significant differences (p>0.05) between the operated and non-operated legs in the peak knee flexor torque or knee flexor torque at a knee flexion angle of 45°, at all angular velocities (60°, 90° and 120°/s). While the peak knee extensor torque was less in the operated leg at all angular velocities, these differences were not significant (p>0.05). However, a significantly reduced (p<0.05) knee extensor torque at a knee flexion angle of 45°, was observed at all speeds.

INTERPRETATION

While patients had recovered their knee flexor strength, they still demonstrated a reduced knee extensor strength profile at 5 years. This demonstrates that the early supervised rehabilitation phase following autologous chondrocyte implantation is not sufficient to restore long-term knee strength, and ongoing patient advice and rehabilitation is required extending beyond this early period. It is unknown how this prolonged reduction in strength may affect long-term graft outcome.

Arthroscopic matrix-induced autologous chondrocyte implantation: 2-year outcomes

PURPOSE

To determine the safety and efficacy of a new arthroscopic technique for matrix-induced autologous chondrocyte implantation (MACI) for articular cartilage defects in the knee.

METHODS

We undertook a prospective evaluation of the first 20 patients treated with the MACI technique (including 14 defects on the femoral condyle and 6 on the tibial plateau), followed up for 24 months after surgery. A 12-week structured rehabilitation program was undertaken by all patients. Patients underwent clinical assessment (Knee Injury and Osteoarthritis Outcome Score, Short Form 36 Health Survey, visual analog pain scale, 6-minute walk test, knee range of motion) before surgery and at 3, 6, 12, and 24 months after surgery and underwent magnetic resonance imaging (MRI) assessment at 3, 12, and 24 months after surgery. MRI evaluation assessed 8 previously defined pertinent parameters of graft repair, as well as a combined MRI composite score.

RESULTS

A significant improvement (P < .05) was shown throughout the postoperative time line for all Knee Injury and Osteoarthritis Outcome Score subscales, the physical component score of the Short Form 36 Health Survey, the frequency and severity of knee pain, and the 6-minute walk test. An improvement in pertinent morphologic parameters of graft repair was observed to 24 months, whereas a good to excellent graft infill score and MRI composite score were observed at 24 months after surgery in 90% and 70% of patients, respectively.

CONCLUSIONS

We report a comprehensive 24-month follow-up in the first 20 patients who underwent the arthroscopic MACI technique. This technique is a safe and efficacious procedure with improved clinical and radiologic outcomes over the 2-year period.

Short-term outcome of the second generation characterized chondrocyte implantation for the treatment of cartilage lesions in the knee

PURPOSE

To evaluate short-term clinical and MRI outcome of the second generation characterized chondrocyte implantation (CCI) for the treatment of cartilage defects in the knee.

METHODS

Thirty-two patients aged 15-51 years with single International Cartilage Repair Society (ICRS) grade III/IV symptomatic cartilage defects of different locations in the knee were treated with CCI using a synthetic collagen I/III membrane to cover the defect. Clinical outcome was measured over 36 months by the Knee injury and Osteoarthritis Outcome Score (KOOS) and Visual Analogue Scale (VAS) for pain. Serial magnetic resonance imaging (MRI) scans of 22 patients were scored using the original and modified Magnetic resonance Observation of Cartilage Repair Tissue (MOCART) system.

RESULTS

The patients included in this study showed a significant gradual clinical improvement after CCI. The MRI findings of this pilot study were considered to be promising. No signs of deterioration were observed. A complete or hypertrophic filling was observed in 76.5% of the cases at 24 months of follow-up. No preventive effect of an avital membrane on the occurrence of hypertrophic repair tissue was observed on MRI. Three failures were observed among the 32 patients until now (9.4%).

CONCLUSIONS

This investigation provided useful information on the efficacy of this treatment. The short-term clinical and MRI outcome are promising. Large-scale and long-term trials are mandatory to confirm the results and the reliability of this procedure.

LEVEL OF EVIDENCE

IV.

Karyotyping of human chondrocytes in scaffold-assisted cartilage tissue engineering

Scaffold-assisted autologous chondrocyte implantation (ACI) is an effective clinical procedure for cartilage repair. The aim of our study was to evaluate the chromosomal stability of human chondrocytes subjected to typical cell culture procedures needed for regenerative approaches in polymer-scaffold-assisted cartilage repair. Chondrocytes derived from post mortem donors and from donors scheduled for ACI were expanded, cryopreserved and re-arranged in polyglycolic acid (PGA)-fibrin scaffolds for tissue culture. Chondrocyte redifferentiation was analyzed by electron microscopy, histology and gene expression analysis. Karyotyping was performed using GTG banding and fluorescence in situ hybridization on a single cell basis. Chondrocytes showed de- and redifferentiation accompanied by the formation of extracellular matrix and induction of typical chondrocyte marker genes like type II collagen in PGA-fibrin scaffolds. Post mortem chondrocytes showed up to 1.7% structural and high numbers of numerical (up to 26.7%) chromosomal aberrations, while chondrocytes from living donors scheduled for ACI showed up to 1.8% structural and up to 1.3% numerical alterations. Cytogenetically, cell culture procedures and PGA-fibrin scaffolds did not significantly alter chromosomal integrity of the chondrocyte genome. Human chondrocytes derived from living donors subjected to regenerative medicine cell culture procedures like cell expansion, cryopreservation and culture in resorbable polymer-based scaffolds show normal chromosomal integrity and normal karyotypes.

Cell Seeding Densities in Autologous Chondrocyte Implantation Techniques for Cartilage Repair

Cartilage repair techniques have been among the most intensively investigated treatments in orthopedics for the past decade, and several different treatment modalities are currently available. Despite the extensive research effort within this field, the generation of hyaline cartilage remains a considerable challenge. There are many parameters attendant to each of the cartilage repair techniques that can affect the amount and types of reparative tissue generated in the cartilage defect, and some of the most fundamental of these parameters have yet to be fully investigated. For procedures in which in vitro-cultured autologous chondrocytes are implanted under a periosteal or synthetic membrane cover, or seeded onto a porous membrane or scaffold, little is known about how the number of cells affects the clinical outcome. Few published clinical studies address the cell seeding density that was employed. The principal objective of this review is to provide an overview of the cell seeding densities used in cell-based treatments currently available in the clinic for cartilage repair. Select preclinical studies that have informed the use of specific cell seeding densities in the clinic are also discussed.