Chondral Lesions of the Knee: An Evidence-Based Approach

Enhancing Cartilage Repair in Osteoarthritis Using Platelet Lysates and Arthroscopic Microfracture

Background

Osteoarthritis (OA) is the most prevalent joint degenerative disease. MF is considered as a first-line treatment for OA. In the long term, the cartilage tissue regenerated after MF is fibrocartilage. In this study, we examine whether combined treatment of MF and Platelet lysate (PL) can inhibit promotion of cartilage repair and antifibrosis.

Methods

OA rat model established by the modified Hulth method. Rat PL injected into treated knee joints after MF surgery. The expression levels of metabolic and fibrosis molecules (Col2, Mmp13, Col1, Col3, α-SMA, and Ctgf) of chondrocytes were examined by immunohistochemistry. Cell immunofluorescence was used to assess bone marrow MSCs (BMSCs) proliferation. Transwell assays evaluated BMSCs migration, and qPCR and Western blot analyzed the mechanisms of PL. Moreover, a retrospective analysis was conducted to determine the clinical efficacy and safety of the combined treatment of MF and PL on OA patients.

Results

In vivo data showed that the combined treatment of MF and PL significantly alleviated joint pain, protected chondrocytes and inhibited synovial fibrosis on OA rats, as was confirmed by upregulation of Collagen II and downregulation of Mmp13, Col1, Col3, α-SMA, and Ctgf. Such anti-OA and antifibrosis effects of the combined treatment of MF and PL were superior to MF alone. In vitro data showed that PL induced cellular chondrogenic differentiation and migration of BMSCs, suggesting that PL facilitated stem cell homing to the cartilage injury sites and promoted cartilage repair and regeneration. Furthermore, the clinical data showed significant improvements of pain reduction and cartilage repair in OA patients.

Conclusion

This study demonstrated the anti-OA and antifibrosis effects of the combination of MF and PL, providing a promising synergistic therapeutic option for the treatment of OA.

Variable Return-to-Sport Rates with Improved Pain and Patient-Reported Outcomes Following Osteochondral Allograft Transplantation: A Systematic Review

Osteochondral allograft transplantation (OCA) of the knee is a reliable surgical technique for managing symptomatic full-thickness chondral lesions ≥2 cm2 in young and active patients. There is a need for comprehensive analysis of recent studies among a growing body of literature to better understand the outcomes of OCA among athletic patients, particularly in terms of return to sports participation and graft longevity. To systematically review existing literature reporting the return-to-sport (RTS) outcomes and patient-reported outcome measures (PROMs) following OCA of the knee among athletic patients. A systematic review was performed in PubMed, Web of Science, and Embase from database inception through December 22, 2024. Studies that reported RTS outcomes after knee OCA were included. Data were analyzed descriptively, and methodological quality was assessed using the Methodological Index for Non-Randomized Studies. Inclusion criteria were met by 13 studies involving 699 patients. The mean patient age was 31.8 years (range 15.2-52.6), with a mean follow-up of 59.9 months (range 24-87.5). Reported RTS rates ranged from 59.4 to 90.9%. The mean time to RTS ranged from 9.0 to 14.6 months; one study documented a median RTS time of 16 months. Between 27.3 and 79.1% of athletes made RTS at the same level, 13.5 to 63.6% at higher levels, and 9.1 to 31.6% at lower levels. Significant (p < 0.05) improvements were noted in Tegner (delta -1.8 to 1.4), Visual Analog Scale-Pain (delta -5.7 to -3.7), and International Knee Documentation Committee scores (delta 25 to 33.0). The most common complications were deep vein thrombosis/pulmonary embolism (1.3%), symptomatic hardware (0.72%), and infections (0.72%). Graft failure ranged from 0 to 10.8%, and reoperation from 0 to 50%. OCA of the knee demonstrates variable RTS rates, with improved postoperative pain and outcomes scores. Graft failure occurred in 0 to 10.8% of patients. IV, Systematic Review of Level III and IV studies.

Treatment of osteoarthritic knee with high tibial osteotomy and allogeneic human umbilical cord blood-derived mesenchymal stem cells combined with hyaluronate hydrogel composite

BACKGROUND

Delaying total knee arthroplasty is crucial for middle-aged patients with severe osteoarthritis. The long-term outcomes of high tibial osteotomy (HTO) remain uncertain. Recently, mesenchymal stem cells (MSCs) have shown promising potential in enhancing cartilage regeneration. Therefore, this study aimed to assess cartilage regeneration following the implantation of allogeneic human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) with HTO.

METHODS

In this case series, ten patients underwent hUCB-MSC implantation with HTO. The median age was 58.50 (range: 57.00-60.00) years, and the mean body mass index was 27.81 (range: 24.42-32.24) kg/m2. Clinical outcomes, including the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), visual analog scale (VAS), Physical Component Score (PCS) and Mental Component Score (MCS) from the 36-Item Short-Form Health Survey (SF-36), were evaluated 6 months, 1 year, and 2 years postoperatively. Cartilage status of the medial femoral condyle (MFC) was assessed during hardware removal surgery, at least 2 years after the initial procedure, and compared with preoperative MFC cartilage status regarding lesion size and International Cartilage Repair Society (ICRS) grade. Radiological assessments included the Kellgren-Lawrence (KL) grading system for medial compartment osteoarthritis and hip-knee-ankle (HKA) angle.

RESULTS

Significant improvements were observed in WOMAC scores (preoperative: 57.00 (range: 44.75-63.00), postoperative: 27.50 (range: 22.25-28.75)), VAS scores (preoperative: 66.25 (range: 48.00-74.25), postoperative: 26.25 (range: 14.50-31.13)), SF-36 PCS (preoperative: 27.97 (range: 26.64-31.25), postoperative: 55.31 (range: 51.64-62.50)), and SF-36 MCS (preoperative: 41.04 (range: 29.95-50.96), postoperative: 63.18 (range: 53.83-65.16)) 2 years postoperatively (p = 0.002, 0.002, 0.002, and 0.020, respectively). The MFC chondral lesion demonstrated significant improvement in both lesion size (preoperative: 7.00 cm² (range: 4.38-10.50 cm²), postoperative: 0.16 cm² (range: 0.00-1.75 cm²), p = 0.002) and ICRS grade (preoperative: 4 (range: 4-4), postoperative: 1 (range: 1-2.25), p = 0.002). Additionally, the KL grade significantly decreased from 3 (range: 3-3) preoperatively to 2 (range: 2-2) postoperatively, while the HKA angle was corrected from 7.50° (range: 7.00-10.25°) preoperatively to -1.00° (range: -3.5-0.00°) postoperatively.

CONCLUSIONS

hUCB-MSC implantation with HTO is an effective treatment for medial compartment osteoarthritis and varus deformities, resulting in significant improvements in cartilage regeneration and overall clinical outcomes.

TRIAL REGISTRATION

NCT04234412.

Advances in cell therapy for orthopedic diseases: bridging immune modulation and regeneration

Orthopedic diseases pose significant challenges to public health due to their high prevalence, debilitating effects, and limited treatment options. Additionally, orthopedic tumors, such as osteosarcoma, chondrosarcoma, and Ewing sarcoma, further complicate the treatment landscape. Current therapies, including pharmacological treatments and joint replacement, address symptoms but fail to promote true tissue regeneration. Cell-based therapies, which have shown successful clinical results in cancers and other diseases, have emerged as a promising solution to repair damaged tissues and restore function in orthopedic diseases and tumors. This review discusses the advances and potential application of cell therapy for orthopedic diseases, with a particular focus on osteoarthritis, bone fractures, cartilage degeneration, and the treatment of orthopedic tumors. We explore the potential of mesenchymal stromal cells (MSCs), chondrocyte transplantation, engineered immune cells and induced pluripotent stem cells to enhance tissue regeneration by modulating the immune response and addressing inflammation. Ultimately, the integration of cutting-edge cell therapy, immune modulation, and molecular targeting strategies could revolutionize the treatment of orthopedic diseases and tumors, providing hope for patients seeking long-term solutions to debilitating conditions.

Use of MACI (Autologous Cultured Chondrocytes on Porcine Collagen Membrane) in the United States: Expanded Experience over 5,000 Cases

ObjectiveTo determine whether there are differences in MACI (matrix-induced autologous chondrocyte implantation) treatment in the United States, by comparing cartilage defects and patient characteristics between the initial 1,000 patients treated with the next 5,000MethodsFollowing initial analysis of the first 1,000 consecutive patients treated with MACI, data were collected and analyzed for the subsequent 5,000. Patients were identified by MACI lot number and surgery date. Adverse events were summarized with descriptive statistics. Group differences were assessed with t-tests and chi-square, with significance set at P < 0.05.ResultsFive thousand adults (5,198 knees) were implanted with MACI by 1,130 surgeons. Patient sex (male 49.2%) was evenly split, and the mean age was 33.6 years. Most patients had a single cartilage defect treated, and the mean defect size was 4.4 cm2. The patella was the most treated surface (38.4%), followed by the medial femoral condyle (25.7%). Most patients (85.5%) had concomitant surgical procedures at the time of cartilage biopsy procurement. There were statistically significant differences in the number of patella (P < 0.001), medial femoral condyle (P < 0.001), and "not specified" (P = 0.008) between groups. Mean defect size and mean total defect size were both larger (P < 0.001 and P = 0.009, respectively) in the subsequent 5,000 patients.ConclusionThe utilization of MACI has remained consistent. Patient demographics and concomitant surgical procedures between the first 1,000 MACI patients and subsequent 5,000 MACI patients were comparable. Patellofemoral defects were the most treated in both subsets, and an overall low rate of adverse events was observed.

Texture Analysis of Cartilage Repair Tissue Maturation: Comparison of Two Cartilage Repair Methods and Correlation with MOCART 2.0

OBJECTIVE

The objective of this study was to assess the maturation of matrix-associated autologous chondrocyte transplantation (MACT) grafts up to 2 years after the surgery using gray-level co-occurrence matrix (GLCM) texture analysis of quantitative T2 maps, compare the results with the microfracturing technique (MFX) control group, and relate these results to the morphological MOCART 2.0 score.

DESIGN

A subcohort of 37 patients from prospective, multi-center study underwent examination on a 3T MR scanner, including a T2 mapping sequence at 3, 12, and 24 months after surgery. Changes between the time-points in the mean T2 values and 20 GLCM features extracted from T2 maps were assessed in repair tissue, tissue adjacent to the repair site, and the reference cartilage for both procedures.

RESULTS

Significant correlations were found between the MOCART 2.0 and GLCM features for both surgical procedures. There were no significant differences between MACT and MFX. We identified significant intra-group changes in T2 and autocorrelation (3M-12M: P = 0.002; 3M-24M: P = 0.004), dissimilarity (3M-24M: P = 0.01), homogeneity (3M-24M: P = 0.013), and correlation (3M-24M: P = 0.036), sum average (3M-12M: P = 0.001; 3M-24M: P = 0.002), and information measure (3M-24M: P < 0.001) in the MACT repair tissue. MACT models revealed differences in GLCM between all combinations of ROI types at almost all time-points. In the case of MFX, the significant differences were mainly between repair and reference tissue at 12 months.

CONCLUSION

Texture analysis provides a useful extension to T2 mapping. Texture features are correlated to the morphological outcome and reveal differences in the process of maturation between MACT and MFX.

Charting a quarter-century of commercial cartilage regeneration products

Functional cartilage regeneration remains difficult to achieve despite decades of research. Dozens of commercial products have been proposed, with each targeting different facets of successful cartilage engineering, including mechanical properties, integration, lubrication and inflammation; however, there remains a lack of breakthroughs in meaningful clinical outcomes. Prior research categorized commercial products based on their components and elucidated challenges faced during the market approval process. This paper, for the first time, comprehensively reviews the properties of commercial products covering the last 25 years, including design trends in components, compatibility with minimally invasive surgery, indications for cartilage defects, long-term follow-up, as well as active sponsorship support of the International Cartilage Regeneration and Joint Preservation Society (ICRS). We aim to summarize the key factors for potentially successful commercial products and elucidate overarching trends in technology development in this field. Given that no revolutionary products have yielded significantly improved clinical results, emerging products compete with one another on user-friendliness and cost-efficiency. Other relevant characteristics include compatibility with minimally invasive surgery, extensiveness of required surgery (one-stage vs. two-stage), use of versatile artificial polymers and application of cells and biomaterials. Specific products continue to lead the market due to their cost-efficiency or indications for larger cartilage defects. However, they have been shown to result in no significant improvement upon clinical follow-up. Thus, there is a need for products that surpass current commercial products and show clinical effectiveness. Translation potential of this article: This review analyzes product components, compatibility with minimally invasive surgery, indication for cartilage defect areas, clinical performance as well as sponsorship for the World Conference of International Cartilage Regeneration & Joint Preservation Society, based on information about cartilage regeneration products from 1997 to 2023. It shines a light on future development of design and commercialization of cartilage products.

Prognostic Factors for Clinical Outcome and Cartilage Regeneration after Implantation of Allogeneic Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells in Large-Sized Cartilage Defects with Osteoarthritis

OBJECTIVE

To analyze the prognostic factors for clinical outcomes and cartilage regeneration after the implantation of allogeneic human umbilical cord blood mesenchymal stem cell (hUCB-MSC) for treating large-sized cartilage defects with osteoarthritis.

DESIGN

This study is a case-series with multiple subgroup analyses that divides the included patients into multiple subgroups based on various factors. Overall, 47 patients who underwent hUCB-MSC implantation were included. The patient-reported outcomes, magnetic resonance imaging (MRI), and second-look arthroscopy were used to assess the outcomes.

RESULTS

Combined realignment surgery significantly correlated with clinical outcomes, particularly pain. No other factors significantly influenced the clinical outcomes in short-term period. Subgroups with large defect sizes or meniscal insufficiency showed significantly poor MRI and arthroscopy outcomes (MRI, P = 0.001, P = 0.001; arthroscopy, P = 0.032, P = 0.042). The logistic regression showed that patients with a 1 cm2 larger defect size were 1.91 times less likely to achieve favorable MRI outcomes (P = 0.017; odds ratio [OR], 1.91). Cut-off value to predict the poor outcome was >5.7 cm2 (area under the curve, 0.756). A cartilage defect size >5.7 cm2 was the major poor prognostic factor for cartilage regeneration on MRI (P = 0.010; OR, 17.46). If the postoperative alignment shifted by 1° opposite to the cartilage defect, it was 1.4 times more likely to achieve favorable MRI outcomes (P = 0.028; OR, 1.4).

CONCLUSION

Combining realignment surgery showed a better prognosis for pain improvement. Cartilage defect size, meniscal function, and postoperative alignment are significant prognostic factors for cartilage regeneration. A cartilage defect size >5.7 cm2 was significantly related to poor cartilage regeneration.

Arthroscopic Autologous Minced Cartilage Implantation of Cartilage Defects in the Knee: A 2-Year Follow-up of 62 Patients

Background

Symptomatic cartilage defects of the knee joint are frequently diagnosed and can be treated with different available surgical methods. Nevertheless, there is currently no gold standard treatment for all indications. Minced cartilage implantation is increasingly coming into focus as a refined surgical technique.

Purpose

To investigate the 2-year clinical and radiological outcomes of arthroscopic autologous minced cartilage repair with the standardized commercial implantation system AutoCart.

Study Design

Case series; Level of evidence, 4.

Methods

A total of 62 consecutive patients were included and prospectively evaluated preoperatively and at 3, 6, 12, and 24 months postoperatively. Outcomes were assessed using the Knee injury and Osteoarthritis Outcome Score (KOOS), visual analog scale (VAS) for pain, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Single Assessment Numeric Evaluation (SANE), and Tegner activity scale at all follow-up time points. The examination of preoperative magnetic resonance imaging (MRI) was performed using the Area Measurement and Depth and Underlying Structures (AMADEUS) score, and the examination of MRI at 24 months was performed using the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) 2.0 score.

Results

There were 34 male and 28 female patients (mean age, 38.79 ± 10.78 years) with symptomatic cartilage lesions with a mean defect size of 2.53 ± 1.24 cm2. Lesions were predominantly International Cartilage Repair Society grade 3 located in the region of the femoral condyles. Concomitant surgery was performed in 40.3% of patients. The total KOOS score significantly improved from 62.4 ± 13.1 at baseline to 74.4 ± 15.9 at 24 months (P < .001). The secondary outcome measures of the VAS, WOMAC, and SANE showed a similar pattern, with score improvements in the follow-up period compared to baseline. The mean AMADEUS score was 64.75 ± 13.87, while the mean MOCART 2.0 score was 62.88 ± 9.86, among 20 available patients. The revision surgery rate was 8.1% mainly because of hypertrophy (6.5%).

Conclusion

Among this cohort of patients, minced cartilage implantation demonstrated satisfying 2-year outcomes with increased patient-reported outcome measure scores from 3 to 24 months postoperatively. Regenerated tissue quality on MRI was comparable to that using other cartilage repair methods and showed no associations with patient characteristics or patient-reported outcome measures. Larger cohorts, longer postoperative intervals, and comparable trials are needed to further evaluate the role of this technique in treating cartilage defects.

Treatment of bone-cartilage defects with dual-layer tissue-engineered scaffolds loaded with icariin and quercetin

Over the past few decades, significant research has been conducted on tissue-engineered constructs for cartilage repair. However, there is a growing interest in addressing subchondral bone repair along with cartilage regeneration. This study focuses on a bilayer tissue engineering scaffold loaded with icariin (ICA) and quercetin (QU) for simultaneous treatment of knee joint cartilage and subchondral bone defects. The cytotoxicity of dual-layer scaffolds loaded with ICA and QU was assessed through live/dead cell staining. Subsequently, these dual-layer scaffolds loaded with ICA and QU were implanted into cartilage and subchondral bone defects in Sprague-Dawley (SD) rats. The repair effects were evaluated through macroscopic observation, computed tomography, and immunohistochemistry. After 12 weeks of implantation of dual-layer scaffolds loaded with ICA and QU into the cartilage and bone defects of SD rats, better repair effects were observed in both cartilage and bone defects compared to the blank control group. We found that the dual-layer tissue-engineered scaffold loaded with ICA and QU had excellent biocompatibility and could effectively repair articular cartilage and subchondral bone injuries, showing promising prospects for clinical applications.

Hydrogel-Enhanced Autologous Chondrocyte Implantation for Cartilage Regeneration-An Update on Preclinical Studies

Autologous chondrocyte implantation (ACI) and matrix-induced ACI (MACI) have demonstrated improved clinical outcomes and reduced revision rates for treating osteochondral and chondral defects. However, their ability to achieve lasting, fully functional repair remains limited. To overcome these challenges, scaffold-enhanced ACI, particularly utilizing hydrogel-based biomaterials, has emerged as an innovative strategy. These biomaterials are intended to mimic the biological composition, structural organization, and biomechanical properties of native articular cartilage. This review aims to provide comprehensive and up-to-date information on advancements in hydrogel-enhanced ACI from the past decade. We begin with a brief introduction to cartilage biology, mechanisms of cartilage injury, and the evolution of surgical techniques, particularly looking at ACI. Subsequently, we review the diversity of hydrogel scaffolds currently undergoing development and evaluation in preclinical studies for articular cartilage regeneration, emphasizing chondrocyte-laden hydrogels applicable to ACI. Finally, we address the key challenges impeding effective clinical translation, with particular attention to issues surrounding fixation and integration, aiming to inform and guide the future progression of tissue engineering strategies.

Initial Outcomes of Single versus Multiple-Plug Osteochondral Allograft Transplantation for Osteochondral Defects of the Knee: A Matched Cohort Analysis

Although several prior studies have described the outcomes of osteochondral allograft (OCA) transplantation for single osteochondral lesions, there is a paucity of comparative data on outcomes of single versus multiple OCA transplants. We aimed to describe the initial outcomes of single-plug versus multiple-plug knee OCA transplants at a minimum of 1 year of follow-up. We hypothesized that there would be no difference in patient-reported outcome measures (PROMs) between patients undergoing single-plug and multiple-plug OCA transplants at a minimum of 1 year of follow-up. We retrospectively reviewed the prospectively collected data of patients undergoing OCA transplantation for large (>2 cm2) osteochondral defects of the knee. Thirty patients who underwent multiple-plug (2 + ) OCA transplants (either single surface using the snowman technique or multi-surface) were 1:1 age, sex, and body mass index (BMI) matched with 30 patients who underwent single-plug OCA transplants. PROMs, including the International Knee Documentation Committee (IKDC) and Knee Injury and Osteoarthritis Outcome Score (KOOS) subscores, were obtained both preoperatively and at a minimum of 1 year postoperatively. Failure was defined as a revision OCA or conversion to unicompartmental knee arthroplasty (UKA) or total knee arthroplasty (TKA). The cohort comprised 30 females (31 affected left knees), with an average age of 37 ± 10.3 years and median follow-up of 2.0 years (interquartile range: 1.7-2.5 years). There was a significant increase in PROMs from the preoperative to the postoperative period for the entire cohort and the single-plug versus multiple-plug subgroups (p < 0.01). There was no difference between the groups with respect to the percentage of patients who achieved the minimal clinically important difference (MCID) for each PROM (p > 0.05). There were two failures, both in the single-plug group, with a mean time to failure of 3.5 years. There was no difference in the initial outcomes between patients undergoing single-plug versus multiple-plug OCA transplant at the short-term follow-up. LEVEL OF EVIDENCE::  Level IV, case series.

Editorial Commentary: Evaluation for Cartilage Lesions on Magnetic Resonance Imaging Continues to Improve: Artificial Intelligence Applications May Result in Higher Sensitivity and Specificity

Accurate detection of cartilage lesions of the knee is required to offer patient-specific care and can alter surgical intervention options. To date, diagnostic arthroscopy remains the gold standard yet often requires the need for staged operative procedure for treatment. Magnetic resonance imaging (MRI) is the most accurate imaging modality with high specificity, yet even with recent advances, MRI has limited specificity. Newer scanners (3T) and updated scanning sequences (3-dimensional MRI and quantitative MRI) are most sensitive in characterizing cartilage lesions of the knee, but these resources are not available to all users. Promising new avenues for patient-specific MRI scans along with the utilization of artificial intelligence will more accurately identify and quantify lesion size, location, and depth.

Quantitative Magnetic Resonance Imaging Had Greater Sensitivity in Diagnosing Chondral Lesions of the Knee: A Systematic Review and Meta-analysis

PURPOSE

To investigate the accuracy and reliability of magnetic resonance imaging (MRI) in identifying and grading chondral lesions and explore the optimal imaging technique to image cartilage.

METHOD

A comprehensive search was conducted on Medline, Embase, and Cochrane Library. Eligible cohort studies published before August 2022 were included. The study reports used MRI to diagnose and grade cartilage lesions, with intraoperative findings as the reference standard. Summary estimates of diagnostic performance were obtained. The reliability of MRI interpretation was summarized. Subgroup analyses were performed based on assessed imaging techniques, field strength, and joint surface.

RESULTS

Forty-three trials and 3,706 patients were included in the systematic review. The overall area under curve for hierarchical summarized receiver operating characteristics was 0.91 (95% confidence interval [CI] 0.88-0.93). The pooled sensitivity for quantitative MRI, 3-dimensional MRI, and 2-dimensional MRI was 0.82 (95% CI 0.64-0.92), 0.79 (95% CI 0.74-0.83), and 0.63 (95% CI 0.51-0.73), respectively. The pooled sensitivity of 3 Tesla (3T), 1.5 Tesla (1.5T), and <1.5 Tesla MRI was 0.79 (95% CI 0.72-0.85), 0.67 (95% CI 0.60-0.74), and 0.55 (95% CI 0.39-0.71), respectively. There were differences in interobserver consistency across different studies.

CONCLUSIONS

In general, MRI had high specificity in discriminating normal cartilage, but its sensitivity for identifying chondral lesions is less optimal. Further analysis showed that quantitative MRI, 3D MRI, and 3T MRI demonstrate greater sensitivity compared with 2D MRI, 1.5T MRI, and <1.5 Tesla MRI.

LEVEL OF EVIDENCE

Level III, systematic review of Level II and III studies.

Autologous platelet-rich plasma and fibrin-augmented minced cartilage implantation in chondral lesions of the knee leads to good clinical and radiological outcomes after more than 12 months: A retrospective cohort study of 71 patients

Purpose

The treatment of cartilage lesions remains a challenge. Matrix-associated autologous chondrocyte implantation has evolved to become the gold standard procedure. However, this two-step procedure has crucial disadvantages, and the one-step minced cartilage procedure has gained attention. This retrospective study aimed to evaluate the clinical and radiological outcome of an all-autologous minced cartilage technique in cartilage lesions at the knee joint.

Methods

In this retrospective cohort study, 71 patients (38.6 years ± 12.0, 39,4% female) with a magnetic resonance imaging (MRI) confirmed grade III-IV cartilage defect at the medial femur condyle (n = 20), lateral femur condyle (n = 2), lateral tibia plateau (n = 1), retropatellar (n = 28) and at the trochlea (n = 20) were included. All patients were treated with an all-autologous minced cartilage procedure (AutoCart™). Clinical knee function was evaluated by the Tegner score, visual analogue scale, the subjective and objective evaluation form of the International Knee Documentation Committee and the Knee Injury and Osteoarthritis Outcome Score (KOOS). MRI analyses were performed by magnetic resonance observation of cartilage repair tissue (MOCART) 2.0 knee score. Follow-up examination was 13.7 ± 4.2 (12-24) months postoperative.

Results

All clinical scores significantly improved after surgical intervention (p < 0.0001), especially the subgroup sports and recreation of KOOS showed clear changes from baseline in the follow-up examination. In the postoperative MRI evaluation, 39 of 71 patients showed a complete fill of the cartilage defect without subchondral changes in 78% of the patients in the MOCART 2.0 score in the follow-up analysis. None of the patients showed adverse effects, which are linked to the minced cartilage procedure during the time of follow-up.

Conclusion

An all-autologous minced cartilage technique for chondral lesions at the knee joint seems to be an effective and safe treatment method with good clinical and radiological short-term results.

Level of Evidence

Level IV.

Age influences the efficacy of osteochondral autograft transfer: Promising results for patients under 40

BACKGROUND

Previous research using osteochondral autograft transfer (OAT) has shown poorer outcomes with increasing patient age. The aim of this article is to evaluate a cohort of patients that received an OAT and to correlate their clinical results with their age at procedure.

METHODS

Patients that underwent an OAT to treat an osteochondral (OC) lesion with a minimum 24-month follow-up were included. Patients were categorized into two groups based on their age at procedure (<40 years and ≥40 years). Postoperatively, each patient completed the Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC), and Lysholm scales.

RESULTS

51 patients were included (35<40 years, 16≥40 years). Mean follow-up was 4.2 years (2-7). For patients<40 years, IKDC averaged 80.8 (SD 15.9) versus 71.2 (SD 19.4) in ≥40 years (p=0.03). For patients <40 years, Lysholm averaged 85.9 (SD 10.8) versus 77.0 (SD 21.6) in ≥40 years (p=0.02). For patients<40 years, KOOS averaged 78.3 (SD 11.8) versus 68.9 (SD 18.5) in ≥40 years (p=0.01). There was a 100% sensibility in identifying all the patients with a poor IKDC and Lysholm from 34 years old (AUC 0.76 and 0.8).

CONCLUSIONS

OAT has better outcomes in patients younger than 40 years compared to patients older than 40 years. Based on the prognostic capacity of age, the ideal candidate for an OAT is a patient younger than 34 years old.

Age influences the efficacy of osteochondral autograft transfer: Promising results for patients under 40

BACKGROUND

Previous research using osteochondral autograft transfer (OAT) has shown poorer outcomes with increasing patient age. The aim of this article is to evaluate a cohort of patients that received an OAT and to correlate their clinical results with their age at procedure.

METHODS

Patients that underwent an OAT to treat an osteochondral (OC) lesion with a minimum 24-month follow-up were included. Patients were categorized into two groups based on their age at procedure (<40 years and ≥40 years). Postoperatively, each patient completed the Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC), and Lysholm scales.

RESULTS

51 patients were included (35<40 years, 16≥40 years). Mean follow-up was 4.2 years (2-7). For patients<40 years, IKDC averaged 80.8 (SD 15.9) versus 71.2 (SD 19.4) in ≥40 years (p=0.03). For patients <40 years, Lysholm averaged 85.9 (SD 10.8) versus 77.0 (SD 21.6) in ≥40 years (p=0.02). For patients<40 years, KOOS averaged 78.3 (SD 11.8) versus 68.9 (SD 18.5) in ≥40 years (p=0.01). There was a 100% sensibility in identifying all the patients with a poor IKDC and Lysholm from 34 years old (AUC 0.76 and 0.8).

CONCLUSIONS

OAT has better outcomes in patients younger than 40 years compared to patients older than 40 years. Based on the prognostic capacity of age, the ideal candidate for an OAT is a patient younger than 34 years old.

A novel mechanism behind irreversible development of cartilage degradation driven articular cartilage defects revealed by rat model: The chain reaction initiated by extracellular vesicles delivered LOC102546541

BACKGROUND

Articular cartilage defects (ACD) are injuries with a diameter greater than 3 mm, resulting from wear and tear on joints. When the diameter of the defect exceeds 6 mm, it can further damage the surrounding joint cartilage, causing osteoarthritis (OA). Try to explain why OA is an irreversible disease, we hypothesize that damaged articular chondrocytes (DAC) may have reduced capacities to repair cartilage because its extracellular vesicle (EVs) that might directly contribute to OA formation.

METHODS

In this study, DAC-EVs and AC-EVs were isolated using ultracentrifugation. Next-generation sequencing was employed to screen for a pathogenic long non-coding RNA (lncRNA). After verifying its function in vitro, the corresponding small interfering RNA (siRNA) was constructed and loaded into extracellular vesicles, which were then injected into the knee joint cavities of rats.

RESULTS

The results revealed that DAC-EVs packaged lncRNA LOC102546541 acts as a competitive endogenous RNA (ceRNA) of MMP13, down-regulating miR-632. Consequently, the function of MMP13 in degrading the extracellular matrix is enhanced, promoting the development of osteoarthritis.

CONCLUSIONS

This study uncovered a novel mode of OA pathogenesis using rat models, which DAC deliver pathogenic LOC102546541 packaged EVs to normal articular chondrocytes, amplifying the degradation of the extracellular matrix. Nonetheless, the functions of highly homologous human gene of LOC102546541 need to be verified in the future.

Cartilage Integrity: A Review of Mechanical and Frictional Properties and Repair Approaches in Osteoarthritis

Osteoarthritis (OA) is one of the most common causes of disability around the globe, especially in aging populations. The main symptoms of OA are pain and loss of motion and function of the affected joint. Hyaline cartilage has limited ability for regeneration due to its avascularity, lack of nerve endings, and very slow metabolism. Total joint replacement (TJR) has to date been used as the treatment of end-stage disease. Various joint-sparing alternatives, including conservative and surgical treatment, have been proposed in the literature; however, no treatment to date has been fully successful in restoring hyaline cartilage. The mechanical and frictional properties of the cartilage are of paramount importance in terms of cartilage resistance to continuous loading. OA causes numerous changes in the macro- and microstructure of cartilage, affecting its mechanical properties. Increased friction and reduced load-bearing capability of the cartilage accelerate further degradation of tissue by exerting increased loads on the healthy surrounding tissues. Cartilage repair techniques aim to restore function and reduce pain in the affected joint. Numerous studies have investigated the biological aspects of OA progression and cartilage repair techniques. However, the mechanical properties of cartilage repair techniques are of vital importance and must be addressed too. This review, therefore, addresses the mechanical and frictional properties of articular cartilage and its changes during OA, and it summarizes the mechanical outcomes of cartilage repair techniques.

Enhancement of hyaline cartilage and subchondral bone regeneration in a rat osteochondral defect model through focused extracorporeal shockwave therapy

Aims

To explore the efficacy of extracorporeal shockwave therapy (ESWT) in the treatment of osteochondral defect (OCD), and its effects on the levels of transforming growth factor (TGF)-β, bone morphogenetic protein (BMP)-2, -3, -4, -5, and -7 in terms of cartilage and bone regeneration.

Methods

The OCD lesion was created on the trochlear groove of left articular cartilage of femur per rat (40 rats in total). The experimental groups were Sham, OCD, and ESWT (0.25 mJ/mm2, 800 impulses, 4 Hz). The animals were euthanized at 2, 4, 8, and 12 weeks post-treatment, and histopathological analysis, micro-CT scanning, and immunohistochemical staining were performed for the specimens.

Results

In the histopathological analysis, the macro-morphological grading scale showed a significant increase, while the histological score and cartilage repair scale of ESWT exhibited a significant decrease compared to OCD at the 8- and 12-week timepoints. At the 12-week follow-up, ESWT exhibited a significant improvement in the volume of damaged bone compared to OCD. Furthermore, immunohistochemistry analysis revealed a significant decrease in type I collagen and a significant increase in type II collagen within the newly formed hyaline cartilage following ESWT, compared to OCD. Finally, SRY-box transcription factor 9 (SOX9), aggrecan, and TGF-β, BMP-2, -3, -4, -5, and -7 were significantly higher in ESWT than in OCD at 12 weeks.

Conclusion

ESWT promoted the effect of TGF-β/BMPs, thereby modulating the production of extracellular matrix proteins and transcription factor involved in the regeneration of articular cartilage and subchondral bone in an OCD rat model.

Chitosan-based scaffold augmentation to microfractures: Stable results at mid-term follow-up in patients with patellar cartilage lesions

Purpose

Patellar cartilage lesions are a frequent and challenging finding in orthopaedic clinical practice. This study aimed to evaluate a chitosan-based scaffold's mid-term clinical and imaging results patients with patellar cartilage lesions.

Methods

Thirteen patients (nine men, four women, 31.3 ± 12.7 years old) were clinically evaluated prospectively at baseline, 12, 24 and at a final minimum follow-up of 60 months (80.2 ± 14.7) with International Knee Documentation Committee (IKDC) subjective, Knee Injury and Osteoarthritis Outcome Score and Tegner scores. A magnetic resonance analysis was performed at the last follow-up using the Magnetic resonance Observation of CArtilage Repair Tissue (MOCART) 2.0 score.

Results

An overall significant clinical improvement in the scores was observed from baseline to all follow-ups, with stable clinical results from 24 months to the mid-term evaluation. The IKDC subjective score passed from 46.3 ± 20.0 at baseline to 70.1 ± 21.5 at the last follow-up (p = 0.029). Symptoms' duration before surgery negatively correlated with the clinical improvement from baseline to the final follow-up (p = 0.013) and sex influenced the improvement of activity level from the preoperative evaluation to the final follow-up, with better results in men (p = 0.049). In line with the clinical findings, positive results were documented in terms of cartilage repair quality with a mean MOCART 2.0 score of 72.4 ± 12.5.

Conclusions

Overall, the use of this chitosan-based scaffold provided satisfactory results with a stable clinical improvement up to mid-term follow-up, which should be confirmed by further high-level studies to be considered a suitable surgical option to treat patients affected by patellar cartilage lesions.

Level of Evidence

Level IV, prospective case series.

Outcomes of Particulated Juvenile Articular Cartilage and Association With Defect Fill in Patients With Full-Thickness Patellar Chondral Lesions

Background

Cartilage restoration procedures for patellar cartilage defects have produced inconsistent results, and optimal management remains controversial. Particulated juvenile articular cartilage (PJAC) allograft tissue is an increasingly utilized treatment option for chondral defects, with previous studies demonstrating favorable short-term outcomes for patellar chondral defects.

Purpose

To identify whether there is an association between defect fill on magnetic resonance imaging (MRI) with functional outcomes in patients with full-thickness patellar cartilage lesions treated with PJAC.

Study Design

Case series; Level of evidence, 4.

Methods

A retrospective review of prospectively collected data was conducted on patients treated with PJAC for a full-thickness symptomatic patellar cartilage lesion between March 2014 and August 2019. MRI was performed for all patients at 6, 12, and 24 months postoperatively. Patient-reported outcome measures (PROMs) were obtained preoperatively and at 1, 2, and >2 years postoperatively. Clinical outcome scores-including the International Knee Documentation Committee (IKDC) score, the Kujala, the Knee injury and Osteoarthritis Outcome Score-Physical Function Short Form (KOOS-PS), the Knee Injury and Osteoarthritis Outcome Score-Quality of Life (KOOS-QoL), and the Hospital for Special Surgery Pediatric Functional Activity Brief Scale (HSS Pedi-FABS)-were analyzed and evaluated for a relationship with tissue fill on MRI.

Results

A total of 70 knees in 65 patients (mean age, 26.6 ± 8.1 years) were identified, of which 68 knees (97%) underwent a concomitant patellar stabilization or offloading procedure. Significant improvements were observed on all postoperative PROM scores at the 1-, 2-, and >2-year follow-up except for the Pedi-FABS, which showed no significant difference from baseline. From baseline to the 2-year follow-up, the KOOS-QoL improved from 24.7 to 62.1, the IKDC improved from 41.1 to 73.5, the KOOS-PS improved from 35.6 to 15, and the Kujala improved from 52 to 86.3. Imaging demonstrated no difference in the rate of cartilage defect fill between the 3-month (66%), 6-month (72%), 1-year (74%), and ≥2-year (69%) follow-ups. No association was observed between PROM scores and the percent fill of cartilage defect on MRI at the 1- and 2-year follow-up.

Conclusion

PROM scores were significantly improved at the 2-year follow-up in patients who underwent PJAC for full-thickness patellar cartilage defects. On MRI, a cartilage defect fill of >66% was achieved by 3 months in most patients. In our sample, PROM scores were not significantly associated with the defect fill percentage at the short-term follow-up.

Autologous Chondrocyte Implantation Is Not Better Than Arthroscopic Debridement for the Treatment of Symptomatic Cartilage Lesions of the Knee: Two-Year Results From a Randomized-Controlled Trial

Purpose

To compare the functional and patient-reported outcome measures after autologous chondrocyte implantation (ACI) and arthroscopic debridement (AD) in symptomatic, isolated cartilage injuries larger than 2 cm2 in patients aged 18 to 50 years.

Methods

Twenty-eight patients were included and randomized to ACI (n = 15) or AD (n = 13) and followed for 2 years. The primary outcome was the change in the Knee injury and Osteoarthritis Outcome Score (KOOS) Quality of Life (QoL) subscale.

Results

The mean age at inclusion was 34.1 (standard deviation [SD] 8.5) years. There were 19 (68%) male patients. The mean size of the lesion was 4.2 (SD 1.7) cm2. There was a statistically significant and clinically meaningful improvement in patient-reported outcome measures from baseline to 2 years in both groups. The improvement from baseline to final follow-up for the primary endpoint (the KOOS QoL subscale) was larger for the AD group (39.8, SD 9.4) compared with the ACI group (23.8, SD 6.7), but this difference was not statistically significant (P = .17). However, according to a mixed linear model there were statistically significantly greater scores in the AD group for several KOOS subscales at several time points, including KOOS QoL, KOOS pain, and KOOS sport and recreation at 2 years.

Conclusions

This study indicates that AD followed by supervised physiotherapy is equal to or better than ACI followed by supervised physiotherapy in patients with isolated cartilage lesions of the knee larger than 2 cm2. The improvement in KOOS QoL score from baseline to 2 years was clinically meaningful for both groups (23.8 points for ACI and 39.8 points AD), and larger for the AD group by 16 points.

Level of Evidence

Level I, prospective randomized controlled trial.

Implantation of hUCB-MSCs generates greater hyaline-type cartilage than microdrilling combined with high tibial osteotomy

PURPOSE

To compare the outcomes of treating large cartilage defects in knee osteoarthritis using human allogeneic umbilical cord blood-derived mesenchymal stem cell (hUCB-MSC) implantation or arthroscopic microdrilling as a supplementary cartilage regenerative procedure combined with high tibial osteotomy (HTO).

METHODS

This 1-year prospective comparative study included 25 patients with large, near full-thickness cartilage defects (International Cartilage Repair Society grade ≥ IIIB) in the medial femoral condyles and varus malalignment. Defects were treated with hUCB-MSC implantation or arthroscopic microdrilling combined with HTO. The primary outcomes were pain visual analogue scale and International Knee Documentation Committee subjective scores at 12, 24 and 48 weeks. Secondary outcomes included arthroscopic, histological and magnetic resonance imaging assessments at 1 year.

RESULTS

Fifteen and 10 patients were treated via hUCB-MSC implantation and microdrilling, respectively. Baseline demographics, limb alignment and clinical outcomes did not significantly differ between the groups. Cartilage defects and total restored areas were significantly larger in the hUCB-MSC group (7.2 ± 1.9 vs. 5.2 ± 2.1 cm2, p = 0.023; 4.5 ± 1.4 vs. 3.0 ± 1.6 cm2, p = 0.035). The proportion of moderate-to-strong positive type II collagen staining was significantly higher in the hUCB-MSC group compared to that in the microdrilled group (93.3% vs. 60%, respectively). Rigidity upon probing resembled that of normal cartilage tissue more in the hUCB-MSC group (86.7% vs. 50.0%, p = 0.075). Histological findings revealed a higher proportion of hyaline cartilage in the group with implanted hUCB-MSC (p = 0.041).

CONCLUSION

hUCB-MSC implantation showed comparable clinical outcomes to those of microdrilling as supplementary cartilage procedures combined with HTO in the short term, despite the significantly larger cartilage defect in the hUCB-MSC group. The repaired cartilage after hUCB-MSC implantation showed greater hyaline-type cartilage with rigidity than that after microdrilling.

LEVEL OF EVIDENCE

Level II, Prospective Comparative Cohort Study.

Catalpol promotes articular cartilage repair by enhancing the recruitment of endogenous mesenchymal stem cells

Articular cartilage defect is challenged by insufficient regenerative ability of cartilage. Catalpol (CA), the primary active component of Rehmanniae Radix, could exert protective effects against various diseases. However, the impact of CA on the treatment of articular cartilage injuries is still unclear. In this study, full-thickness articular cartilage defect was induced in a mouse model via surgery. The animals were intraperitoneally injected with CA for 4 or 8 weeks. According to the results of macroscopic observation, micro-computed tomography CT (μCT), histological and immunohistochemistry staining, CA treatment could promote mouse cartilage repair, resulting in cartilage regeneration, bone structure improvement and matrix anabolism. Specifically, an increase in the expression of CD90, the marker of mesenchymal stem cells (MSCs), in the cartilage was observed. In addition, we evaluated the migratory and chondrogenic effects of CA on MSCs. Different concentration of CA was added to C3H10 T1/2 cells. The results showed that CA enhanced cell migration and chondrogenesis without affecting proliferation. Collectively, our findings indicate that CA may be effective for the treatment of cartilage defects via stimulation of endogenous MSCs.

Comparison of Minced Cartilage Implantation with Autologous Chondrocyte Transplantation in an In Vitro Inflammation Model

The current gold standard to treat large cartilage defects is autologous chondrocyte transplantation (ACT). As a new surgical method of cartilage regeneration, minced cartilage implantation (MCI) is increasingly coming into focus. The aim of this study is to investigate the influence of chondrogenesis between isolated and cultured chondrocytes compared to cartilage chips in a standardized inflammation model with the proinflammatory cytokine TNFα. Articular chondrocytes from bovine cartilage were cultured according to the ACT method to passage 3 and transferred to spheroid culture. At the same time, cartilage was fragmented (<1 mm3) to produce cartilage chips. TNFα (20 ng/mL) was supplemented to simulate an inflammatory process. TNFα had a stronger influence on the passaged chondrocytes compared to the non-passaged ones, affecting gene expression profiles differently between isolated chondrocytes and cartilage chips. MCI showed less susceptibility to TNFα, with reduced IL-6 release and less impact on inflammation markers. Biochemical and histological analyses supported these findings, showing a greater negative influence of TNFα on the passaged pellet cultures compared to the unpassaged cells and MCI constructs. This study demonstrated the negative influence of TNFα on chondrogenesis in a chondrocyte spheroid culture and cartilage fragment model. Passaged chondrocytes are more sensitive to cytokine influences compared to non-passaged cells and chondrons. This suggests that MCI may have superior regeneration potential in osteoarthritic conditions compared to ACT. Further investigations are necessary for the translation of these findings into clinical practice.

The posterior tibial slope affects the measurement reliability regarding the radiographic parameter of the knee

BACKGROUND

Posterior tibial slope (PTS) exhibits considerable variability among individuals and is anticipated to influence the accuracy of radiographic measurements related to the knee. Despite this potential impact, there is a lack of prior research investigating how PTS affects the accuracy of these measurements. Therefore, this study aimed to investigate the effect of PTS on the measurement reliability regarding the radiographic parameter of the knee.

METHODS

The medical records of patients who took full-length anteroposterior radiographs of the lower limb between January 2020 and June 2022 were evaluated retrospectively. Radiographic parameters related to the knee joint characteristics such as osteoarthritis grade, hip-knee-ankle angle, weight-bearing line ratio, medial proximal tibial angle (MPTA), lateral distal femoral angle, joint-line convergence angle (JLCA), and PTS were measured. Subjects were classified into 3 groups according to PTS (group A, PTS < 4°; group B, PTS ≥ 4° and < 8°; group C, PTS ≥ 8°), and the measurement reliability for the radiographic variables was compared between groups. The intra- and inter-observer agreements were assessed using the kappa coefficients, intra-class correlation coefficients (ICC), and Bland-Altman plots.

RESULTS

A total of 175 limbs (86 patients) were included in this study. As the intra- and inter-observer reliability for PTS ranged over 0.9, grouping was performed based on the average of the measured PTSs. The inter-observer reliability of the MPTA and JLCA decreased as the PTS increased (ICCs for MPTA in Groups A, B, and C: 0.889, 0.796, and 0.790, respectively; ICCs for JLCA in Groups A, B and C: 0.916, 0.859, and 0.843, respectively), whereas there were no remarkable differences in other variables. Similar trends were observed in the comparisons of intra-observer reliability and Bland-Altman plots also showed consistent results.

CONCLUSION

The larger the PTS, the lower the measurement reliability regarding the radiographic parameters of the knee that includes the joint line, such as MPTA and JLCA. Given the occasional challenge in accurately identifying the knee joint line in patients with a relatively large PTS, careful measurement of radiographic parameters is crucial and utilizing repetitive measurements for verification may contribute to minimizing measurement errors.

Surgical Treatment of Focal Chondral Lesions of the Knee in the Military Population: Current and Future Therapies

INTRODUCTION

Chondral and osteochondral defects of the knee are common injuries in the military population that have a significant impact on readiness. Definitive treatment of these injuries is challenging since cartilage has a limited capacity for self-repair and regeneration. Management is particularly challenging in military patients who maintain a higher level of activity similar to athletes. Existing surgical techniques have variable results and often long recovery times, sparking the development of several new innovative technologies to return service members back to duty more quickly and effectively after cartilage injury. The purpose of this article is to review the current and future surgical treatments for chondral and osteochondral knee lesions and their relevance in managing these injuries in the military.

METHODS

In this review article, we describe the current treatments for chondral and osteochondral defects of the knee, reporting on outcomes in military populations. We explore emerging treatment modalities for cartilage defects, reporting innovations, stage of research, and current data. Published results of each treatment option in military populations are reviewed throughout the article.

RESULTS

This review includes 12 treatments for chondral lesions. Of these therapies, four are considered synthetic and the remaining are considered regenerative solutions. Regenerative therapies tend to perform better in younger, healthier populations with robust healing capacity. Success of treatment depends on lesions and patient characteristics. Nearly all modalities currently available in the USA were successful in improving patients from presurgical function in the short (<6 months) term, but the long-term efficacy is still challenged. Upcoming technologies show promising results in clinical and animal studies that may provide alternative options desirable for the military population.

CONCLUSIONS

The current treatment options for cartilage lesions are not entirely satisfactory, usually with long recovery times and mixed results. An ideal therapy would be a single procedure that possesses the ability to enable a quick return to activity and duty, alleviate pain, provide long-term durability, and disrupt the progression of osteoarthritis. Evolving technologies for cartilage lesions are expanding beyond currently available techniques that may revolutionize the future of cartilage repair.

Cell Therapy Approaches for Articular Cartilage Regeneration

Articular cartilage is a common cartilage type found in a multitude of joints throughout the human body. However, cartilage is limited in its regenerative capacity. A range of methods have been employed to aid adults under the age of 45 with cartilage defects, but other cartilage pathologies such as osteoarthritis are limited to non-steroidal anti-inflammatory drugs and total joint arthroplasty. Cell therapies and synthetic biology can be utilized to assist not only cartilage defects but have the potential as a therapeutic approach for osteoarthritis as well. In this review, we will cover current cell therapy approaches for cartilage defect regeneration with a focus on autologous chondrocyte implantation and matrix autologous chondrocyte implantation. We will then discuss the potential of stem cells for cartilage repair in osteoarthritis and the use of synthetic biology to genetically engineer cells to promote cartilage regeneration and potentially reverse osteoarthritis.

Suitable characteristics in the selection of human allogeneic chondrocytes donors to increase the number of viable cells for cartilage repair

Autologous chondrocyte implantation has shown optimal long-term outcomes in the treatment of cartilage lesions. The challenge for a single-stage approach lies in obtaining sufficient number of cells with high viability. The answer could lie in supplementing or replacing them with allogenic chondrocytes coming from cadaveric donors. In the present work, we aimed to compare the number of viable cells isolated from cartilage of live and cadaveric donors and to determine the suitable characteristics of the best donors. A total of 65 samples from donors aged from 17 to 55 years, either women or men, were enrolled in this study (33 living vs. 32 cadaveric). The mean time of hours from death to processing samples in cadaveric donors was higher compared to live donors (64.3 ± 17.7 vs. 4.6±6.4). The number of isolated chondrocytes per gram of cartilage was higher in cadaveric donors (5.389 × 106 compared to 3.067 × 106 in living donors), whereas the average of cell viability was comparable in both groups (84.16% cadaveric, 87.8% alive). It is possible to obtain viable chondrocytes from cartilage harvested from cadaveric donors, reaching a similar cell number and viability to that obtained from the cartilage of living donors.

Marrow stimulation procedures for high-grade cartilage lesions during surgical repair of medial meniscus root tear yielded suboptimal outcomes, whilst small lesions showed surgical eligibility

PURPOSE

To investigate the surgical outcomes of arthroscopic pull-out repair for medial meniscus root tear (MMRT) combined with the marrow stimulation procedures (MSP) for accompanying high-grade cartilage lesions.

METHODS

Patients who underwent arthroscopic pull-out repair for MMRT between 2010 and 2019 were retrospectively reviewed. Patients who had at least 3 years of follow-up were included and classified into two groups according to whether MSP (microfracture or microdrilling) were performed on cartilage lesions in the medial tibiofemoral joint (group 1, patients with International Cartilage Repair Society [ICRS] grade 0-3a lesions and did not undergo MSP; group 2, patients with ICRS grade 3b-3d lesions and underwent MSP). Comparative analyses, including non-inferiority trials, were conducted between groups for subjective and objective outcomes. In addition, group 2 was further divided into two subgroups according to cartilage lesion size and compared with group 1 (group S, ≤ 2.0 cm2; group L, > 2.0 cm2).

RESULTS

A total of 94 patients were included (group 1, 68 patients; group 2, 26 patients). There were no significant differences in clinical scores at postoperative 3 years and final follow-up between groups 1 and 2, but group 2 failed to satisfy the non-inferiority criteria compared to group 1 overall. In objective outcomes, group 2 did not meet the non-inferiority criteria for the rate of osteoarthritis progression compared to group 1, and it also showed a significantly higher proportion of high-grade osteoarthritis at final follow-up (P = 0.044) and a higher degree of osteoarthritis progression than group 1 (P = 0.03 for pre- to postoperative 3 years, and P = 0.006 for pre- to final follow-up). In additional evaluations comparing the subgroups of group 2 and group 1, group S showed relatively favourable results compared to group L in objective outcomes at final follow-up.

CONCLUSION

Patients who underwent arthroscopic pull-out repair for MMRT combined with MSP for accompanying high-grade cartilage lesions showed suboptimal outcomes compared to those with no or low-grade lesions at mid-term follow-up. High-grade cartilage lesions ≤ 2.0 cm2 may be candidates for the surgical repair of MMRT if MSP are performed, but those with larger lesions may require alternative treatment strategies.

LEVEL OF EVIDENCE

III.

Microfracture- and Xeno-Matrix-Induced Chondrogenesis for Treatment of Focal Traumatic Cartilage Defects of the Knee: Age-Based Mid-Term Results

The aim of this study was to investigate clinical and instrumental outcomes of the autologous matrix-induced chondrogenesis (AMIC) technique for the treatment of isolated traumatic condyle and femoropatellar cartilage lesions. A total of 25 patients (12 males, 13 females, mean age 47.3 years) treated between 2018 and 2021 were retrospectively reviewed and subdivided into two groups based on age (Group A, age < 45 years; Group B, age > 45 years). A clinical evaluation was performed using the International Knee Documentation Committee (IKDC), Lysholm score and Visual Analogue Score (VAS). Cartilage regeneration was evaluated via magnetic resonance (1.5 Tesla) and classified according to a Magnetic resonance Observation of CArtilage Repair Tissue (MOCART) scoring system. At a minimum follow-up of 2 years, Group A patients obtained greater instrumental results in comparison to group B: in fact, the MOCART score was statistically significantly correlated with IKDC (r = 0.223) (p < 0.001) exclusively in group A. Nevertheless, a significant improvement in clinical functionality was shown in Group B (p < 0.001), demonstrating that this technique is safe, reproducible and capable of offering satisfactory clinical results regardless of age.

Regeneration of joint surface defects by transplantation of allogeneic cartilage: application of iPS cell-derived cartilage and immunogenicity

BACKGROUND

Because of its poor intrinsic repair capacity, articular cartilage seldom heals when damaged.

MAIN BODY

Regenerative treatment is expected for the treatment of articular cartilage damage, and allogeneic chondrocytes or cartilage have an advantage over autologous chondrocytes, which are limited in number. However, the presence or absence of an immune response has not been analyzed and remains controversial. Allogeneic-induced pluripotent stem cell (iPSC)-derived cartilage, a new resource for cartilage regeneration, reportedly survived and integrated with native cartilage after transplantation into chondral defects in knee joints without immune rejection in a recent primate model. Here, we review and discuss the immunogenicity of chondrocytes and the efficacy of allogeneic cartilage transplantation, including iPSC-derived cartilage.

SHORT CONCLUSION

Allogeneic iPSC-derived cartilage transplantation, a new therapeutic option, could be a good indication for chondral defects, and the development of translational medical technology for articular cartilage damage is expected.

Autologous minced cartilage repair for chondral and osteochondral lesions of the knee joint demonstrates good postoperative outcomes and low reoperation rates at minimum five-year follow-up

PURPOSE

Minced cartilage is a one-step, autologous procedure with promising short-term results. The aim of the present study was to evaluate mid-term results in a patient cohort with chondral and osteochondral lesions in the knee joint treated with minced cartilage.

METHODS

From 2015 through 2016, a total of 34 consecutive patients were treated with a single-step, autologous minced cartilage for knee chondral and osteochondral lesions. Numeric analogue scale (NAS) for pain and knee function were obtained prior to surgery and at 12, 24 and 60 months postoperatively. Secondary outcomes, including Lysholm score, Tegner activity score, and the International Knee Documentation Committee (IKDC) score, were recorded at final follow-up. MRI examinations of patients with unplanned radiological follow-up were analysed using the MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score.

RESULTS

A total of 28 patients (44.1% females, age at surgery: 29.5 ± 11.5 years) were available at a mean follow-up of 65.5 ± 4.1 months. Mean defect size was 3.5 ± 1.8 cm2. NAS for pain decreased from a median of 7 (range: 2-10) preoperatively to 2 (0-8) postoperatively. NAS knee function improved from a median of 7 (range: 2-10) to 3 (0-7) after five years, respectively. Satisfactory Lysholm (76.5 ± 12.5), IKDC (71.6 ± 14.8) and Tegner activity (4, range 3-9) scores were reported at final follow-up. Of all patients, 21(75%) and 19 (67.9%) reached or exceeded the PASS for the IKDC- and Lysholm score at final follow-up, respectively. The average overall MOCART 2.0 scores for all postoperatively performed MRIs (n = 23) was 62.3 ± 17.4. Four (14.2%) postoperative complications were directly linked to minced cartilage, one (3.5%) of which required revision surgery.

CONCLUSION

One-step, autologous minced cartilage repair of chondral and osteochondral lesions of the knee without the necessity for subchondral bone treatment demonstrated good patient-reported outcomes, low complication rates, and graft longevity at mid-term follow-up. Minced cartilage represents a viable treatment option to more traditional cartilage repair techniques even in mid-term.

LEVEL OF EVIDENCE

Level III.

A Photopolymerizable Biocompatible Hyaluronic Acid Hydrogel Promotes Early Articular Cartilage Repair in a Minipig Model In Vivo

Articular cartilage defects represent an unsolved clinical challenge. Photopolymerizable hydrogels are attractive candidates supporting repair. This study investigates the short-term safety and efficacy of two novel hyaluronic acid (HA)-triethylene glycol (TEG)-coumarin hydrogels photocrosslinked in situ in a clinically relevant large animal model. It is hypothesized that HA-hydrogel-augmented microfracture (MFX) is superior to MFX in enhancing early cartilage repair, and that the molar degree of substitution and concentration of HA affects repair. Chondral full-thickness defects in the knees of adult minipigs are treated with either 1) debridement (No MFX), 2) debridement and MFX, 3) debridement, MFX, and HA hydrogel (30% molar derivatization, 30 mg mL-1 HA; F3) (MFX+F3), and 4) debridement, MFX, and HA hydrogel (40% molar derivatization, 20 mg mL-1 HA; F4) (MFX+F4). After 8 weeks postoperatively, MFX+F3 significantly improves total macroscopic and histological scores compared with all other groups without negative effects, besides significantly enhancing the individual repair parameters "defect architecture," "repair tissue surface" (compared with No MFX, MFX), and "subchondral bone" (compared with MFX). These data indicate that photopolymerizable HA hydrogels enable a favorable metastable microenvironment promoting early chondrogenesis in vivo. This work also uncovers a mechanism for effective HA-augmented cartilage repair by combining lower molar derivatization with higher concentrations.

In-Office Needle Arthroscopy With Cartilage Allograft Extracellular Matrix Application for Cartilage Lesions of the Knee

Chondral and osteochondral lesions of the knee are a common cause of pain, mechanical symptoms, and swelling for patients. The benefits of in-office needle arthroscopy (IONA) include the ability to diagnose and treat chondral or osteochondral lesions in the office, quicker patient recovery, reduced cost, and improved patient satisfaction. The purpose of this technical note is to describe the technique for performing in-office needle arthroscopy for chondral or osteochondral contained lesions of the knee, with special consideration of the technique for obtaining adequate local anesthesia, proper indications, adequate visualization, and the advantages of performing these procedures in the office rather than the operating room.

Patellar Cartilage Bossing Causing Patellofemoral Pain After Cartilage Repair With Hyalofast® Scaffold and Bone Marrow Aspirate Concentrate (BMAC)

Chondral lesions of the knee are common orthopedic issues encountered in daily practice. Hyalofast® (Anika Therapeutics, Bedford, Massachusetts) grafting with bone marrow aspirate concentrate (BMAC) has been shown, in numerous studies, to be clinically efficacious in the surgical treatment of these lesions. We describe a case of chondral lesions in the knee initially successfully treated with arthroscopic chondroplasty and Hyalofast® grafting with BMAC, but who subsequently developed patellar cartilage bossing, causing anterior patellofemoral joint pain eight months after surgery. A 48-year-old gentleman underwent arthroscopic chondroplasty and mini-open cartilage repair with Hyalofast® and BMAC after presenting with right knee pain and swelling affecting his ability to participate in sports. His initial recovery was unremarkable, but he subsequently developed anterior knee pain exacerbated by stair climbing and jogging eight months after the initial surgery. Magnetic resonance imaging revealed bossing of the Hyalofast® graft over the central patella, and intraoperative testing confirmed the impingement. The patient's symptoms resolved immediately following arthroscopic debridement. While Hyalofast® grafting and BMAC remain viable options in the treatment of chondral lesions in the knee, the inability to predict the amount of cartilage repair and recovery may result in pain and impingement symptoms, and surgeons should be aware of such possible complications.

Low-Profile Cartilage Repair With Knotless All-Suture Anchors: Surgical Technique

Osteochondral and pure chondral lesions of the knee are common after patellar dislocations. There are multiple described techniques for the fixation of these lesions, including metallic screws, bioabsorbable screws, bioabsorbable implants, and suture devices. The purpose of this article is to describe a surgical technique for surgical fixation of a lateral condyle chondral lesion using knotless all-suture anchors, with second-look knee arthroscopy illustrating healing of the cartilage repair.

Survivorship After Lateral Meniscal Allograft Transplantation Plus Concurrent Cartilage Procedure in Patients With Poor Cartilage Status: A Comparative Study

BACKGROUND

The effect of a concurrent cartilage procedure in lateral meniscal allograft transplantation (MAT) in patients with bipolar cartilage lesions (high-grade lesions on both the femoral and the tibial side) is not well studied. An objective evaluation of graft status after MAT and a concurrent cartilage procedure has not been reported.

PURPOSE

To investigate the effect of concurrent cartilage procedures and lateral MAT on objective and clinical outcomes, including survival, in patients with bipolar cartilage lesions.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 149 patients with high-grade (International Cartilage Regeneration & Joint Preservation Society grade 3 or 4) cartilage lesions were enrolled and assigned to 1 of 3 groups based on the cartilage procedure and cartilage status at the time of MAT. Femoral cartilage procedures (microfracture, n = 18; osteochondral autograft transfer, n = 13) and lateral MAT were performed in 31 patients with bipolar cartilage lesions (cartilage procedure group). Another 70 patients with bipolar lesions underwent only lateral MAT without cartilage procedure (bipolar lesion group). The remaining 48 patients, who had high-grade lesions only on the tibial side and underwent lateral MAT without a cartilage procedure, were selected as a control group (unipolar lesion group). Anatomic survival was objectively assessed by follow-up magnetic resonance imaging and second-look arthroscopy. Clinical survivorship was determined with a Lysholm score <65 or need for additional surgery, such as revision MAT.

RESULTS

The mean Lysholm score improved from 67.2 ± 15.9 preoperatively to 86.7 ± 11.1 with a mean follow-up of 78.0 ± 51.2 months (P < .001). The postoperative scores were not significantly different between the 3 groups. The estimated 5-year anatomic survival rate in the cartilage procedure group (86.7%) was higher than that in the bipolar lesion group (65.0%; P = .043) but comparable with that in the unipolar lesion group (90.2%; P = .572). The estimated 5-year clinical survival rates were not significantly different between the groups (P = .187).

CONCLUSION

A concurrent femoral cartilage procedure improved the anatomic survival rate in patients with bipolar chondral lesions who underwent lateral MAT. This finding suggests that the cartilage procedure is an effective treatment choice and may improve the status of an allograft after lateral MAT for patients with bipolar cartilage lesions.

Hyalofast Cartilage Repair Surgery with a Full Load-Bearing Rehabilitation Program One Day after Operation Reduces the Time for Professional Athletes to Return to Play

Background and Objectives: This study evaluated the effectiveness of Hyalofast cartilage repair surgery with an early, full load-bearing rehabilitation program one day after the operation for reducing the time needed for professional athletes to return to play. Materials and Methods: This prospective study included 49 patients aged between 19 and 38 years who had undergone surgical reconstruction of cartilage using the microfracture technique combined with a Hyalofast scaffold. All patients were active professional athletes. Early rehabilitation was implemented from the first postoperative day, fully loading the operated limb. A clinical evaluation was based on the KOOS and SF-36 questionnaires used during subsequent follow-up visits. All patients underwent magnetic resonance imaging (MRI) to evaluate the effect of the surgery after one year. Results: The clinical results demonstrated a statistically significant improvement in the number of complaints about pain and in the quality of life of the patients, measured in all of the applied scales, with comparisons made between six months or one year post-surgery and pre-surgery. Importantly for athletes, the parameter related to sports and recreation improved from 14 ± 11.1 to 95 ± 7.7 6 months after surgery and to 99.8 ± 1.8 one year after surgery. The overall quality of life score improved from 30 ± 18 to 88 ± 8.8 one year after surgery. Conclusions: These results show that this approach significantly shortened the time needed for the athletes to return to sports at the same level as before the surgery (athletes returned to sports in approximately 2.5-3 months). The mean follow-up time was 19.75 months. This technique can be considered a viable option for the treatment of cartilage injuries in professional athletes, allowing them to return to play more quickly in a safe and healthy way.

In vivo rAAV-mediated human TGF-β overexpression reduces perifocal osteoarthritis and improves osteochondral repair in a large animal model at one year

OBJECTIVE

Osteoarthritis (OA) is a serious consequence of focal osteochondral defects. Gene transfer of human transforming growth factor beta (hTGF-β) with recombinant adeno-associated virus (rAAV) vectors offers a strategy to improve osteochondral repair. However, the long-term in vivo effects of such rAAV-mediated TGF-β overexpression including its potential benefits on OA development remain unknown.

METHOD

Focal osteochondral defects in minipig knees received rAAV-lacZ (control) or rAAV-hTGF-β in vivo. After one year, osteochondral repair and perifocal OA were visualized using validated macroscopic scoring, ultra-high-field MRI at 9.4 T, and micro-CT. A quantitative estimation of the cellular densities and a validated semi-quantitative scoring of histological and immunohistological parameters completed the analysis of microarchitectural parameters.

RESULTS

Direct rAAV-hTGF-β application induced and maintained significantly improved defect filling and safranin O staining intensity and overall cartilage repair at one year in vivo. In addition, rAAV-hTGF-β led to significantly higher chondrocyte densities within the cartilaginous repair tissue without affecting chondrocyte hypertrophy and minimized subarticular trabecular separation. Of note, rAAV-hTGF-β significantly improved the adjacent cartilage structure and chondrocyte density and reduced overall perifocal OA development after one year in vivo.

CONCLUSIONS

rAAV-hTGF-β treatment improves long-term osteochondral repair and delays the progression of perifocal OA in a translational model. These findings have considerable potential for targeted molecular approaches to treat focal osteochondral defects.

Conversion Total Knee Arthroplasty after Failed Osteochondral Allograft Reconstruction: Similar Functional Performance with Lower Patient Satisfaction

BACKGROUND

This study presents surgical techniques used in conversion total knee arthroplasty (cTKA) following early failure of large osteochondral allograft joint replacement and compares postoperative patient reported outcomes measures (PROMs) and satisfaction scores with a contemporary primary total knee arthroplasty (pTKA) cohort.

METHODS

We retrospectively evaluated 25 consecutive cTKA patients (26 procedures) to define utilized surgical techniques, radiographic disease severity, preoperative and postoperative PROMs (visual analog scale (VAS) pain, knee injury and osteoarthritis outcome score for joint replacement (KOOS-JR), University of California Los Angeles (UCLA) Activity), expected improvement and postoperative satisfaction (5-point Likert), and reoperations in comparison with an age and body mass index (BMI) propensity matched cohort of 50 pTKA performed for osteoarthritis (52 procedures).

RESULTS

Revision components were used in 12 cTKA cases (46.1%), with 4 cases requiring augmentation (15.4%), and 3 cases utilizing varus-valgus constraint (11.5%). While no significant differences were noted in expectation level or in other PROMs, mean patient reported satisfaction was lower in the conversion group (4.4 +/- 1.1 vs 4.8 +/- 0.5 points, P=0.02). High cTKA satisfaction was associated with higher postoperative KOOS-JR (84.4 vs 64.2 points, P=0.01) and trend towards higher UCLA activity (6.9 vs 5.7 points, P=0.08). Four patients in each group underwent manipulation (15.3 vs 7.6%, P=0.42), and one primary TKA patient was treated for early postoperative infection (0 vs 1.9%, P=1.0).

CONCLUSION

Conversion TKA following failed biological replacement was associated with similar postoperative improvement as in pTKA. Lower patient reported cTKA satisfaction was associated with lower postoperative KOOS-JR scores.

Revision Lateral Femoral Condyle Osteochondral Allograft Transplantation With the Snowman Technique After Failed Previous Oblong Osteochondral Allograft

Osteochondral allograft transplantation provides components of both cartilage and subchondral bone and can be used in large and multifocal defects where autologous procedures are limited by donor-site morbidity. Osteochondral allograft transplantation is particularly appealing in the management of failed cartilage repair, as larger defects and subchondral bone involvement are often present, and the use of multiple overlapping plugs might be considered. The described technique provides our preoperative workup and reproducible surgical approach for patients who have undergone previous osteochondral transplantation with graft failure and are young, active patients who would not be otherwise suited for a knee arthroplasty procedure.

Preclinical Use of FGF-18 Augmentation for Improving Cartilage Healing Following Surgical Repair: A Systematic Review

OBJECTIVE

To evaluate the efficacy of fibroblast growth factor-18 (FGF-18) augmentation for improving articular cartilage healing following surgical repair in preclinical (in vivo) animal models.

DESIGN

A systematic review was performed evaluating the efficacy of FGF-18 augmentation with cartilage surgery compared with cartilage surgery without FGF-18 augmentation in living animal models. Eligible intervention groups were FGF-18 treatment in conjunction with orthopedic procedures, including microfracture, osteochondral auto/allograft transplantation, and cellular-based repair. Outcome variables were: International Cartilage Repair Society (ICRS) score, modified O'Driscoll histology score, tissue infill score, qualitative histology, and adverse events. Descriptive statistics were recorded and summarized for each included study.

RESULTS

In total, 493 studies were identified and 4 studies were included in the final analysis. All studies were randomized controlled trials evaluating in vivo use of recombinant human FGF-18 (rhFGF-18). Animal models included ovine (n = 3) and equine (n = 1), with rhFGF-18 use following microfracture (n = 3) or osteochondral defect repair (n = 1). The rhFGF-18 was delivered via intra-articular injection (n = 2), collagen membrane scaffold (n = 1), or both (n = 1). All studies reported significant, positive improvements in cartilage defect repair with rhFGF-18 compared with controls based on ICRS score (n = 4), modified O'Driscoll score (n = 4), tissue infill (n = 3), and expression of collagen type II (n = 4) (P < 0.05). No adverse events were reported with the intra-articular administration of this growth factor, indicating short-term safety and efficacy of rhFGF-18 in vivo.

CONCLUSION

This systematic review provides evidence that rhFGF-18 significantly improves cartilage healing at 6 months postoperatively following microfracture or osteochondral defect repair in preclinical randomized controlled trials.

Factor affecting the discrepancy in the coronal alignment of the lower limb between the standing and supine radiographs

BACKGROUND

Conflicting results have been reported regarding the factors that can predict the discrepancy in the coronal alignment of the lower limb between radiographs taken in the standing and supine positions. Therefore, this study aimed to investigate factors that can predict discrepancies in the coronal alignment of the lower limb between radiographs taken in the standing and supine positions.

METHODS

We retrospectively evaluated the medical records of patients who underwent full-length anteroposterior radiographs of the lower limb in both standing and supine positions between January 2019 and September 2021. The discrepancy in the coronal alignment of the lower limb between the standing and supine radiographs was defined as the absolute value of the difference in the hip-knee-ankle (HKA) angle between the two radiographs, which is presented as the ΔHKA angle. Correlation and regression analyses were performed to analyse the relationship among ΔHKA angle, demographic data, and several radiographic parameters.

RESULTS

In total, 147 limbs (94 patients) were included in this study. The mean ΔHKA angle was 1.3 ± 1.1° (range, 0-6.5°). The ΔHKA angle was significantly correlated with body mass index and several radiographic parameters, including the HKA angle, joint line convergence angle, and osteoarthritis grade. Subsequent multiple linear regression analysis was performed using the radiographic parameters measured on the supine radiographs with the two separate models from the two observers, which revealed that body mass index and advanced osteoarthritis (Kellgren-Lawrence grades 3 and 4) had a positive correlation with the ΔHKA angle.

CONCLUSIONS

Body mass index and advanced osteoarthritis affected the discrepancy in the coronal alignment of the lower limb between standing and supine radiographs. A discrepancy in the coronal alignment of the lower limb could be more prominent in patients with an increased body mass index and advanced osteoarthritis, corresponding to Kellgren-Lawrence grades 3 and 4.

PEG Reinforced Scaffold Promotes Uniform Distribution of Human MSC-Created Cartilage Matrix

Previously, we used a gelatin/hyaluronic acid (GH)-based scaffold to induce chondrogenic differentiation of human bone marrow-derived mesenchymal stromal cells (hBMSC). The results showed that hBMSCs underwent robust chondrogenesis and facilitated in vivo cartilage regeneration. However, it was noticed that the GH scaffolds display a compressive modulus that is markedly lower than native cartilage. In this study, we aimed to enhance the mechanical strength of GH scaffolds without significantly impairing their chondrosupportive property. Specifically, polyethylene glycol diacrylate (PEGDA) and photoinitiators were infiltrated into pre-formed hBMSC-laden GH scaffolds and then photo-crosslinked. Results showed that infiltration of PEG at the beginning of chondrogenesis significantly increased the deposition of glycosaminoglycans (GAGs) in the central area of the scaffold. To explore the mechanism, we compared the cell migration and proliferation in the margin and central areas of GH and PEG-infiltrated GH scaffolds (GH+PEG). Limited cell migration was noticed in both groups, but more proliferating cells were observed in GH than in GH+PEG. Lastly, the in vitro repairing study with bovine cartilage explants showed that PEG- impregnated scaffolds integrated well with host tissues. These results indicate that PEG-GH hybrid scaffolds, created through infiltrating PEG into pre-formed GH scaffolds, display good integration capacity and represent a new tool for the repair of chondral injury.

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.

Emerging polymeric material strategies for cartilage repair

Cartilage is found throughout the body, serving an array of essential functions. Owing to the limited healing capacity of cartilage, damage or degeneration is often permanent and so requires clinical intervention. Established surgical techniques generally rely on biological grafting. However, recent advances in polymeric materials provide an encouraging alternative to overcome limits of auto- and allografts. For regenerative engineering of cartilage, a polymeric scaffold ideally supports and instructs tissue regeneration while also providing mechanical integrity. Scaffolds direct regeneration via chemical and mechanical cues, as well as delivery and support of exogenous cells and bioactive factors. Advanced polymeric scaffolds aim to direct regeneration locally, replicating the heterogeneities of native tissues. Alternatively, new cartilage-mimetic hydrogels have potential to serve as synthetic cartilage replacements. Prepared as multi-network or composite hydrogels, the most promising candidates have simultaneously realized the hydration, mechanical, and tribological properties of native cartilage. Collectively, the recent rise in polymers for cartilage regeneration and replacement proposes a changing paradigm, with a new generation of materials paving the way for improved clinical outcomes.

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.