Stable clinical long term results after AMIC in the aligned knee

A systematic review on Autologous Matrix Induced Chondrogenesis (AMIC) for chondral knee defects

BACKGROUND

Chondral defects of the knee can be identified in up to 60% of patients undergoing knee arthroscopy. The use of Autologous Matrix Induced Chondrogenesis (AMIC), which combines subchondral microfracture with a collagen membrane,has been increasingly used to treat these defects.

AIMS

This review assesses the clinical, functional, and radiological outcomes of patients undergoing the AMIC procedure and reports any associated complications.

METHODS

Studies with a minimum of 10 patients and fulfilled at least a 12-month follow up period with more than 70% follow up rate were included. Methodological quality was assessed using MINORS (Methodological Index for Non-Randomised Studies) criteria. The meta-analysis compared Lysholm, VAS (Visual Analog Scale), IKDC (International Knee Documentation Committee), KOOS (Knee Injury and Osteoarthritis Outcome Score) Pain, and Tegner clinical outcome measures at baseline and follow up.

RESULTS

18 studies (n = 490 patients) were included. The mean age was 35.2 [SD = 5.0] years and the mean defect size was 3.47 [SD = 0.96] cm2. There was a clinically significant improvement in Lysholm, IKDC, and KOOS scores of 30.36 [95% CI (25.80, 34.93)], 34.05 [95% CI (4.16, 43.95)], and 30.63 [95% CI (24.78, 36.47)] respectively; and reduction in VAS pain score of -4.10 [95%CI (-4.50, -3.71) at follow up. Improvement in Tegner score at follow up was not statistically significant: 0.21 [95% CI (-0.88, 1.30)],(p > 0.05).

CONCLUSION

AMIC is a safe, effective, and reliable technique to treat knee chondral defects which can provide significant clinical, functional, and radiological improvements to patients.

Autologous matrix-induced chondrogenesis provides better outcomes in comparison to autologous minced cartilage implantation in the repair of knee chondral defects

PURPOSE

In symptomatic mid-sized focal chondral defects, autologous matrix-induced chondrogenesis (AMIC) and minced cartilage implantation (MCI) offer two versatile treatment options. This study aimed to conduct a matched-patient analysis of patient-reported outcome measures to compare these two surgical treatment methods for focal chondral defects.

METHODS

At the first centre, patients underwent a single-stage procedure in which autologous cartilage was hand-minced, implanted into the defect and fixed with fibrin glue. At the second centre, patients underwent AMIC, which was fixed in place with fibrin glue. All patients were seen 2-4 years postoperatively. Postoperative outcomes were assessed using the visual analogue scale for pain (VAS), the Lysholm score and the five domains of the knee osteoarthritis outcome score (KOOS). Patients from each surgical centre were matched by age, sex, defect size and defect localisation.

RESULTS

In total, 48 patients from two surgical centres (24 from each site) were matched for sex, age (MCI 30.3 ± 14.9 years vs. AMIC 30.8 ± 13.7 years) and defect size (MCI 2.49 ± 1.5 cm2 vs. AMIC 2.65 ± 1.1 cm2). Significantly better scores in the AMIC cohort were noted for VAS (p = 0.004), Lysholm (p = 0.043) and the KOOS subscales for pain (p = 0.016) and quality of life (p = 0.036). There was a significantly greater proportion of positive responders for Lysholm in the AMIC group (92%) compared with the MCI group (64%).

CONCLUSIONS

The AMIC procedure delivers superior patient outcomes compared with hand-minced autologous cartilage implantation. These are mid-term outcomes, with follow-up between 2 and 4 years.

LEVEL OF EVIDENCE

Level III.

Drop in survivorship 13 years after AMIC procedures in aligned knees: A long-term follow-up

PURPOSE

Autologous matrix-induced chondrogenesis (AMIC) showed promising short-term results comparable to microfracture. This study aims to assess the 19-year outcomes of AMIC, addressing the lack of long-term data.

METHODS

Retrospective cohort of 34 knees treated with AMIC underwent a 19-year follow-up. The primary outcome was AMIC survival, considering total knee arthroplasty as a failure event. Survival analysis for factors that were associated with longer survival of the AMIC was also performed. Clinical and radiological outcome scores were analysed for the AMIC group.

RESULTS

Twenty-three knees were available for follow-up analysis. Of these, 14 (61%) underwent revision surgery for total knee arthroplasty (TKA). The mean time was 13.3 ± 2.5 years (range: 9-17 years). Secondary outcomes showed that increased age at surgery (hazard ratio [HR]: 1.05; p = 0.021) and larger defect size (HR: 1.95; p = 0.018) were risk factors for failure. Concomitant proximal tibial osteotomy (HR: 0.22; p = 0.019) was associated with longer survival. The remaining nine knees (39%) were analysed as a single group. The mean clinical score at follow-up of 18.6 ± 0.9 SD years was 79.5 ± 19.7 SD for the Lysholm score, 1.8 ± 1.5 SD for the visual analog scale score, 74.2 ± 22.4 SD for the KOOS score and a median of 3 (range: 3-4) for the Tegner activity scale.

CONCLUSIONS

The mean survival time of 13.3 years indicates the durability of AMIC in properly aligned knees. Nonetheless, despite a 61% conversion to TKA, the knees that persisted until the 19-year follow-up remained stable, underscoring the procedure's longevity and consistent clinical outcomes.

LEVEL OF EVIDENCE

Level IV.

Autologous Matrix-Induced Chondrogenesis for the Treatment of Hip Acetabular Chondral Lesions Demonstrates Improved Outcomes: A Systematic Review

PURPOSE

To systematically investigate the outcomes of patients who underwent autologous matrix-induced chondrogenesis (AMIC) during hip arthroscopy for the treatment of acetabular chondral lesions due to femoroacetabular impingement syndrome.

METHODS

PubMed and Cochrane were queried in June 2022 to conduct this systematic review using the following keywords: "femoroacetabular impingement," "arthroscopy," "microfracture," and "autologous matrix-induced chondrogenesis." Articles were included if they reported on patient-reported outcomes of AMIC during hip arthroscopy to treat chondral lesions of the hip. The review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. Each study was queried for demographics, lesion classification, surgical treatment, patient-reported outcome scores, revision arthroscopy, and conversion to total hip arthroplasty (THA). A qualitative subanalysis was performed to compare patients undergoing AMIC to patients undergoing microfracture alone if included studies also assessed results of microfracture alone.

RESULTS

Four studies met inclusion criteria and assessed 209 hips undergoing AMIC. The included studies consisted of 99 male and 110 female patients. Mean postoperative follow-up ranged from 1 to 8 years, and mean patient age ranged from 34.3 to 45 years. Three of the 4 included studies reported the modified Harris Hip Score, and all 3 of these studies reported statistically significant improvement in the modified Harris Hip Score at final follow-up (P < .001) with mean preoperative values ranging from 44.5 to 62.8 and mean postoperative values ranging from 78.8 to 95.8. Two of the 4 studies compared patients treated with AMIC to microfracture alone. In these 2 studies, the AMIC groups reported 0 patients converting to THA while the microfracture-alone groups reported a highly variable rate of conversion to THA (2%-32.6%).

CONCLUSIONS

Patients who underwent hip arthroscopy and AMIC for the treatment of femoroacetabular impingement syndrome and acetabular chondral lesions demonstrated improved patient-reported outcomes and low rates of secondary surgeries at short-term follow-up. STUDY DESIGN: Level IV, systematic review of Level III and IV studies.

Arthroscopic and open approaches for autologous matrix-induced chondrogenesis repair of the knee have similar results: a meta-analysis

BACKGROUND

Cartilage defects are debilitating injuries that can reduce quality of life in patients. However, the poor regenerative properties of cartilage mean that cartilage repair remains challenging, and many methods have arisen to address that. Autologous matrix-induced chondrogenesis (AMIC®) is a popular technique to manage cartilage defects. Recent advances have allowed AMIC® to be done arthroscopically, instead of a mini-open arthrotomy approach. This systematic review and meta-analysis aims to investigate whether the arthroscopic approach to AMIC® provides better clinical outcomes than does the mini-open approach, in hopes of delineating a gold standard in cartilage repair.

METHODS

With reference to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, a systematic search of the following databases (PubMed, Embase, Scopus, and Cochrane Library) was performed on 26th October 2022 using a combination of the following search terms: "autologous matrix induced", "chondrogenesis", and "knee". A total of 390 studies were identified, of which, 24 studies were included in our final analysis.

RESULTS

The arthroscopic approach achieves lower Visual Analogue Scale for pain scores. The International Knee documentation Committee) score and Knee Injury and Osteoarthritis Outcome Score were comparable between arthroscopic and open approaches. The open approach achieves a higher Magnetic Resonance Observation of Cartilage Repair Tissue score. Incidence of reported postoperative complications of revision surgery and knee stiffness was higher for the open approach than for the arthroscopic approach, whereas deep vein thrombosis was higher in the arthroscopic approach.

CONCLUSION

The AMIC® repair outcomes indicate that the arthroscopic approach does not hold a distinct advantage over the open approach. The choice of approach should consider surgeon expertise, location of lesion, and patient-specific factors.

LEVEL OF EVIDENCE

Systematic review and meta-analysis; Level III.

Sex does not influence the long-term outcome of matrix-assisted autologous chondrocyte transplantation

PURPOSE

Regenerative techniques for articular cartilage lesions demonstrated heterogeneous clinical results. Several factors may influence the outcome, with sex being one of the most debated. This study aimed at quantifying the long-term influence of sex on the clinical outcome obtained with a regenerative procedure for knee chondral lesions.

METHODS

Matrix-assisted autologous chondrocyte transplantation (MACT) was used to treat 235 knees which were prospectively evaluated with the International Knee Documentation Committee (IKDC), EuroQol visual analogue scale, and Tegner scores at 14-year mean follow-up. A multilevel analysis was performed with the IKDC subjective scores standardised according to the age/sex category of each patient and/or the selection of a match-paired subgroup to compare homogeneous men and women patients.

RESULTS

At 14 years, men and women showed a failure rate of 10.7% and 28.8%, respectively (p < 0.0005). An overall improvement was observed in both sexes. Women had more patellar lesions and men more condylar lesions (p = 0.001), and the latter also presented a higher preinjury activity level (p < 0.0005). Men had significantly higher IKDC subjective scores at all follow-ups (at 14 years: 77.2 ± 18.9 vs. 62.8 ± 23.1; p < 0.0005). However, the analysis of homogeneous match-paired populations of men and women, with standardised IKDC subjective scores, showed no differences between men and women (at 14 years: -1.6 ± 1.7 vs. -1.9 ± 1.6).

CONCLUSION

Men and women treated with MACT for knee chondral lesions presented a significant improvement and stable long-term results. When both sexes are compared with homogeneous match-paired groups, they have similar results over time. However, women present more often unfavourable lesion patterns, which proved more challenging in terms of long-term outcome after MACT.

LEVEL OF EVIDENCE

Level II.

One-stage cartilage repair using the autologous matrix-induced chondrogenesis combined with simultaneous use of autologous adipose tissue graft and adipose tissue mesenchymal cells technique: clinical results and magnetic resonance imaging evaluation at five-year follow-up

PURPOSE

To evaluate medium-term outcomes of knee cartilage defects repair by autologous matrix-induced chondrogenesis combined with simultaneous use of autologous adipose tissue graft and adipose tissue mesenchymal cells, defined as LIPO-AMIC technique.

METHODS

The LIPO-AMIC technique has been used in ICRS degree III-IV knee defects. Eighteen patients have been prospectively evaluated during two and five years both clinically and by MRI.

RESULTS

Patients showed progressive significant improvement of all scores starting early at six months, and further increased values were noted till the last follow-up at 60 months. Mean subjective pre-operative IKDC score of 36.1 significantly increased to 86.4 at 24 months and to 87.2 at 60 months. Mean pre-operative Lysholm score of 44.4 reached 93.5 at two years and 93.5 at five years. MRI examination showed early subchondral lamina regrowth and progressive maturation of repair tissue and filling of defects. The mean total MOCART score showed that a significative improvement from two year follow-up (69.1 points) to last follow-up was 81.9 points (range, 30-100 points, SD 24). Complete filling of the defect at the level of the surrounding cartilage was found in 77.8%.

CONCLUSIONS

Adipose tissue can represent ideal source of MSCs since easiness of withdrawal and definite chondrogenic capacity. This study clearly demonstrated the LIPO-AMIC technique to be feasible for treatment of knee cartilage defects and to result in statistically significant progressive clinical, functional and pain improvement in all treated patients better than what reported for the AMIC standard technique, starting very early from the 6-month follow-up and maintaining the good clinical results more durably with stable results at mid-term follow-up.

Positive outcomes following Autologous Matrix-Induced Chondrogenesis (AMIC) in the treatment of retropatellar chondral lesions: a retrospective analysis of a patient registry

BACKGROUND

The patellofemoral joint is a challenging environment for treating chondral defects. Among the surgical options for the treatment of chondral defects, the single-stage Autologous Matrix-Induced Chondrogenesis (AMIC) procedure uses a porcine collagen I/III membrane to enhance bone-marrow stimulation. However, longer term outcomes data are rare for this specific indication. In order to provide real-world information, an ongoing registry has been established to record patient data and outcomes when AMIC is used to treat chondral and osteochondral lesions.

METHODS

Patient data were retrieved from an ongoing, prospective, multisite registry of patients who had undergone AMIC treatment of chondral defects. We identified 64 patients who had undergone AMIC for patellofemoral chondral defects and for whom pre-operative and at least 1 post-operative score were available were included in this retrospective data analysis. Outcomes were assessed via the KOOS, VAS pain, and the Lysholm scores. Outcomes at the post-operative time-points were analysed using a factorial ANOVA with post-hoc testing while linear regression was used to assess associations between the change in the Lysholm score and lesion size.

RESULTS

There was a significant improvement in Lysholm, VAS pain, and KOOS scores from pre-operative to the 1st year post-operative (p < 0.001), and this was maintained during the follow-up.

CONCLUSIONS

The forces exerted on the patellofemoral joint make this a challenging scenario for chondral repair. Our data demonstrates that the AMIC procedure with a collagen I/III membrane is an effective treatment for retropatellar cartilage lesions, and provides reliable results, with decreased pain and improved function. Importantly, these improvements were maintained through the follow-up period.

Satisfactory patient-reported outcomes in patients treated with impaction bone grafting and autologous matrix-induced chondrogenesis for osteochondral knee defects

PURPOSE

Osteochondral knee defects usually affect young, active patients and may alter knee biomechanics and progressively lead to joint degeneration. Various treatment options exist with autologous, impaction bone grafting in combination with autologous matrix-induced chondrogenesis (BG-AMIC) being a less-expensive, one-step, promising option. The purpose of this study is to evaluate the clinical and radiological mid-term outcomes of large osteochondral lesions treated with BG-AMIC, identify a possible correlation between the two and report postoperative complications and reoperation rate.

METHODS

A retrospective analysis of 25 patients treated with the BG-AMIC technique for knee osteochondral lesions was performed. Patients were assessed using the following PROMs: the IKDC, the KOOS and the Lysholm score, the Tegner activity scale and a patient acceptable symptom state (PASS). The EQ-5D-5L score was used to assess health-related quality of life. Radiological assessment was performed using the MOCART 2.0 score on a 3 T MRI.

RESULTS

At a mean of 3.8 (± 0.8)-year follow-up, all functional scores increased significantly (p < 0.005) when compared to the preoperative baseline. IKDC increased from 44.5 (± 15.9) to 81.4 (± 14.7), KOOS from 41.5 (± 16.1) to 91.6 (± 11.6) and Lysholm from 54.4 (± 23) to 95.2 (± 5.5) (p < 0.005). The EQ-5D-5L score also revealed a significant improvement [59.9 (± 25) to 93.4 (± 10.2), p < 0.005]. Mean Tegner score reached pre-injury levels. The PASS was positive in 100% of patients. The minimum clinically important difference was reached in all PROMs except for the KOOS Sports subscale. There were no re-operations. Morphological evaluation of the repair tissue using the MOCART 2.0 score revealed a mean total score of 52.8 (± 30.5). A statistically significant, positive correlation was found between the MOCART 2.0 score and the IKDC score, the KOOS ADL subscale and the EQ-5D-5L (p < 0.05).

CONCLUSION

BG-AMIC is a safe and reliable option for treating deep, knee osteochondral lesions, providing a statistically significant and clinically important improvement in patient-reported outcomes. No complications were noticed, and no re-operations were performed after the procedure. A moderate positive correlation between the MOCART 2.0 score and the IKDC, KOOS ADL and EQ-5D-5L was noticed. However, this correlation is not necessarily clinically relevant, and excellent clinical results can be expected even in patients with low MOCART scores.

LEVEL OF EVIDENCE

III.

Rate of Conversion to Matrix-Induced Autologous Chondrocyte Implantation After a Biopsy: A Multisurgeon Study

Background

Autologous chondrocyte implantation (ACI) and matrix-induced autologous chondrocyte implantation (MACI) are performed to treat focal chondral defects (FCDs); both are 2-step procedures involving a biopsy, followed by transplantation. There is little published research evaluating ACI/MACI in patients who undergo a biopsy alone.

Purpose

To determine (1) the value of ACI/MACI cartilage biopsies and concomitant procedures in patients with FCDs of the knee and (2) the conversion rate to cartilage transplantation as well as the rate of reoperation.

Study Design

Case series; Level of evidence, 4.

Methods

A retrospective review was performed of 46 patients (63% female) who underwent a MACI (or ACI) biopsy between January 2013 and January 2018. Preoperative data, intraoperative data, and postoperative outcomes were assessed at a minimum of 2 years after the biopsy. The conversion rate from a biopsy to transplantation and the reoperation rate were calculated and analyzed.

Results

Among the 46 patients included, 17 (37.0%) underwent subsequent surgery, with only 12 undergoing cartilage restoration surgery, for an overall transplantation rate of 26.1%. Of these 12 patients, 9 underwent MACI/ACI, 2 underwent osteochondral allograft transplantation (OCA), and 1 underwent particulated juvenile articular cartilage implantation at 7.2 ± 7.5 months after the biopsy. The reoperation rate was 16.7% (1 patient after MACI/ACI and 1 patient after OCA) at 13.5 ± 2.3 months after transplantation.

Conclusion

Arthroscopic surgery with debridement, chondroplasty, loose body removal, meniscectomy/meniscal repair, and other treatment approaches of knee compartment abnormalities at the time of a biopsy appeared to be sufficient in improving function and reducing pain in patients with knee FCDs.

The "hump" a new arthroscopic phenomenon guiding for reliable therapy of osteochondritis dissecans of variable stability status

INTRODUCTION

Despite 150 years of research, there are currently no reliable morphological characteristics that can be used to differentiate between stable and unstable juvenile osteochondritis dissecans (JOCD) lesions in the knee joint. Arthroscopic probing is still the gold standard. In arthroscopic evaluation, a previously undescribed pattern of a cartilaginous convex elevation ("hump") was identified as a new feature and potential sign of JOCD in transition to instability. The aim of the study was to evaluate the clinical outcomes after surgical intervention (drilling) on the "hump".

MATERIALS AND METHODS

In a retrospective case series of sixteen patients with an arthroscopically detectable "hump", the analysis of clinical function scores (Lysholm, Tegner) and morphological MRI monitoring of radiological healing were performed. The assessment of lesion healing was based on pre- and postoperative MRI examinations. The "hump" was defined as an arthroscopically impressive protrusion of the femoral articular surface with a minimally softened, discolored, but intact cartilage margin that, is not mobile upon in the arthroscopic palpation hook test. The primary therapy of choice was drilling of all "humps".

RESULTS

The "hump" could be detected arthroscopically in 16 of 59 JOCD lesions. Specific MRI correlations with the "hump" or arthroscopic unstable lesions could not be detected. Not all "humps" showed signs of MRI-based healing after the drilling, and in some a dissection of the osteochondral flap occurred within the first postoperative year. As a result, secondary refixation became necessary.

CONCLUSION

In the present study, the "hump" was identified as an important differential diagnostic arthroscopic feature of an arthroscopically primarily stable JOCD lesion, potentially placing the lesion at risk of secondary loosening over time. Therefore, drilling alone may not be appropriate in the event of arthroscopic "hump" discovery, but additional fixation may be required to achieve the healing of the lesion.

LEVEL OF EVIDENCE

III.

Autologous Matrix-Induced Chondrogenesis (AMIC) for Focal Chondral Lesions of the Knee: A 2-Year Follow-Up of Clinical, Proprioceptive, and Isokinetic Evaluation

(1) Background: The autologous matrix-induced chondrogenesis (AMIC) is a bio-orthopedic treatment for articular cartilage damage. It combines microfracture surgery with the application of a collagen membrane. The aim of the present study was to report a medium-term follow-up of patients treated with AMIC for focal chondral lesions. (2) Methods: Fourty-eight patients treated surgically and 21 control participants were enrolled in the study. To evaluate the functional outcomes, the proprioceptive (postural stability, postural priority) and isokinetic (peak value of maximum knee extensor and flexor torque in relation to body mass and the total work) measurements were performed. To evaluate the clinical outcomes, the Lysholm score and the IKDC score were imposed. (3) Results: Compared to the preoperative values, there was significant improvement in the first 2 years after intervention in the functional as well as subjective outcome measures. (4) Conclusions: AMIC showed durable results in aligned knees.

Minced Cartilage Is a One-Step Cartilage Repair Procedure for Small Defects in the Knee-A Systematic-Review and Meta-Analysis

Purpose: Approximately 60% of patients undergoing arthroscopy of the knee present with chondral defects. If left untreated, osteochondral lesions can trigger an early onset of osteoarthritis. Many cartilage repair techniques are mainly differentiated in techniques aiming for bone marrow stimulation, or cell-based methods. Cartilage repair can also be categorized in one- and two-stage procedures. Some two-stage procedures come with a high cost for scaffolds, extensive cell-processing, strict regulatory requirements, and limited logistical availability. Minced cartilage, however, is a one-stage procedure delivering promising results in short term follow-up, as noted in recent investigations. However, there is no available literature summarizing or synthesizing clinical data. The purpose of this study was to analyze and synthesize data from the latest literature in a meta-analysis of outcomes after the minced cartilage procedure and to compare its effectiveness to standard repair techniques. Methods: We conducted a systematic review searching the Cochrane, PubMed, and Ovid databases. Inclusion criteria were the modified Coleman methodology Score (mCMS) >60, cartilaginous knee-joint defects, and adult patients. Patient age < 18 years, biomechanical and animal studies were excluded. Relevant articles were reviewed independently by referring to title and abstract. In a systematic review, we compared three studies and 52 patients with a total of 63 lesions. Results: Analysis of Knee Injury and Osteoarthritis Outcome Score (KOOS) sub scores at 12 and 24 months showed a significant score increase in every sub score. Highest mean difference was seen in KOOS sport, lowest in KOOS symptoms (12 month: KOOS sport (Mean difference: 35.35 [28.16, 42.53]; p < 0.0001), lowest in KOOS symptoms (Mean difference: 20.12 [15.43, 24.80]; p < 0.0001)). A comparison of International Knee Documentation Committee (IKDC ) scores visualized a significant score increase for both time points too ((12 month: pooled total mean: 73.00 ± 14.65; Mean difference: 34.33 [26.84, 41.82]; p < 0.00001) (24 month: pooled total mean: 77.64 ± 14.46; mean difference: 35.20 [39.49, 40.92]; p < 0.00001)). Conclusion: Due to no need for separate cell-processing, and thanks to being a one-step procedure, minced cartilage is a promising method for cartilage repair in small defect sizes (mean 2.77 cm2, range 1.3−4.7 cm2). However, the most recent evidence is scarce, and takes only results two years post-surgery into account. Summarized, minced cartilage presents nearly equal short-term improvement of clinical scores (IKDC, KOOS) compared to standard cartilage repair techniques.

Does the Choice of Acellular Scaffold and Augmentation With Bone Marrow Aspirate Concentrate Affect Short-term Outcomes in Cartilage Repair? A Systematic Review and Meta-analysis

BACKGROUND

Matrix-induced chondrogenesis (MIC) is a promising treatment option for critical-size cartilage lesions of the knee; however, there exists substantial heterogeneity in the choice of acellular scaffold matrix for MIC cartilage repairs.

HYPOTHESIS

The choice of acellular matrix will not affect patient outcomes after MIC cartilage repair procedures, and the addition of concentrated bone marrow aspirate (cBMA) will improve short-term patient outcomes regardless of matrix choice.

STUDY DESIGN

Meta-analysis; Level of evidence, 4.

METHODS

Studies were stratified by matrix type: multilayered, single layered, and gel based. Continuous outcomes were analyzed with pairwise meta-analysis using the inverse variance model with random effects applied. Binary outcomes were analyzed as pooled proportions in a single-arm fashion; after which, reconstruction of relative risks (RRs) with confidence intervals was performed using the Katz logarithmic method.

RESULTS

A total of 876 patients were included: 469 received multilayered bioscaffolds; 238, gel-based scaffolds; and 169, single-layered scaffolds. The mean age of patients was 36.2 years (95% CI, 33.9 to 38.4), while the mean lesion size was 3.91 cm² (95% CI, 3.40 to 4.42). The weighted mean follow-up was 23.8 months (95% CI, 20.1 to 27.6). Multilayered bioscaffolds were most effective at improving visual analog scale scores (P = .03; weighted mean difference [WMD], -4.44 [95% CI, -4.83 to -4.06]; P < .001). There were significantly lower risks of incomplete defect filling for gel-based scaffolds when compared with multilayered scaffolds (RR, 0.78 [95% CI, 0.69 to 0.88]; P < .001) and single-layered scaffolds (RR, 0.58 [95% CI, 0.41 to 0.81]; P = .001). Augmentation with cBMA further improved clinical scores across all scaffolds, with significant improvements in Tegner score (P = .02), while decreasing incomplete defect filling rates as well. There was significantly greater improvement in visual analog scale scores (P = .01) for single-layered scaffolds with cBMA augmentation (WMD, -4.88 [95% CI, -5.38 to -4.37]; P < .001) as compared with single-layered scaffolds without cBMA augmentation (WMD, -4.08 [95% CI, -4.46 to -3.71]; P < .001). All significant improvements were below their respective minimum clinically important differences.

CONCLUSION

While cartilage repair with acellular scaffolds provides significant improvements in pain and function for patients, there is insufficient clinical evidence to suggest which scaffold material is the most superior in influencing such improvements. The enhancement of cartilage repair procedures with cBMA may provide further functional improvements and improve defect filling; however, more long-term evidence is required to evaluate the effects.

The subjective knee value is a valid single-item survey to assess knee function in common knee disorders

INTRODUCTION

The patient's perspective plays a key role in judging the effect of knee disorders on physical function. We have introduced the Subjective Knee Value (SKV) to simplify the evaluation of individual's knee function by providing one simple question. The purpose of this prospective study was to validate the SKV with accepted multiple-item knee surveys across patients with orthopaedic knee disorders.

MATERIALS AND METHODS

Between January through March 2020, consecutive patients (n = 160; mean age 51 ± 18 years, range from 18 to 85 years, 54% women) attending the outpatient clinic for knee complaints caused by osteoarthritis (n = 69), meniscal lesion (n = 45), tear of the anterior cruciate ligament (n = 23) and focal chondral defect (n = 23) were invited to complete a knee-specific survey including the SKV along with the Knee Injury Osteoarthritis Outcome Score (KOOS) and the International Knee Documentation Committee subjective knee form (IKDC-S). The Pearson correlation coefficient was used to evaluate external validity between the SKV and each patient-reported outcome measure (PROM) separately. Furthermore, patient's compliance was assessed by comparing responding rates.

RESULTS

Overall, the SKV highly correlated with both the KOOS (R = 0.758, p < 0.05) and the IKDC-S (R = 0.802, p < 0.05). This was also demonstrated across all investigated diagnosis- and demographic-specific (gender, age) subgroups (range 0.509-0.936). No relevant floor/ceiling effects were noticed. The responding rate for the SKV (96%) was significantly higher when compared with those for the KOOS (81%) and the IKDC-S (83%) (p < 0.05).

CONCLUSION

At baseline, the SKV exhibits acceptable validity across all investigated knee-specific PROMs in a broad patient population with a wide array of knee disorders. The simplified survey format without compromising the precision to evaluate individual's knee function justifies implementation in daily clinical practice.

LEVEL OF EVIDENCE

II, cohort study (diagnosis).

Autologous Matrix-Induced Chondrogenesis (AMIC) for Isolated Retropatellar Cartilage Lesions: Outcome after a Follow-Up of Minimum 2 Years

PURPOSE

To evaluate autologous matrix-induced chondrogenesis (AMIC) for isolated focal retropatellar cartilage lesions and the influence of patellofemoral (PF) anatomy on clinical outcomes at a minimum of 2-year follow-up.

METHODS

Twenty-nine consecutive patients (31 knees) who underwent retropatellar AMIC with a mean age of 27.9 ± 11.0 years were evaluated at a follow-up averaging 4.1 ± 1.9 years (range, 2-8 years). Patient factors, lesion morphology, and patient-reported outcome measures, including Knee Injury and Osteoarthritis Outcome Score (KOOS), Tegner, Kujula score, and visual analogue scale (VAS) score were collected. PF anatomy was assessed on pre- and postoperative imaging, and subsequently correlated to outcome scores and failure to determine risk factors for poor outcome.

RESULTS

At final follow-up, the AMIC graft failed in 4 cases (12.9%) at a mean follow-up of 21 ± 14.1 months. Patients with failed grafts had a significantly smaller patellar and Laurins's PF angle than patients whose graft did not fail (P = 0.008 and P = 0.004, respectively). Concomitant corrective surgery for patellar instability was performed in 29 knees (93.5%). Grafts that did not fail presented with an average Kujala score of 71.3 ± 16.9, KOOS Pain of 76.2 ± 16.6 and Tegner scores of 4.2 ± 1.8. The patellar angle was significantly associated with the patient's satisfaction level (r = 0.615; P < 0.001).

CONCLUSION

AMIC for retropatellar cartilage lesions in combination with concomitant corrective surgery for patellar instability results in low failure rate with satisfactory clinical outcome and patient satisfaction of almost 80% at mid-term follow-up. As most failures occurred in patients without concurrent tibial tubercle osteotomy and both a smaller patellar and Laurins's PF angle were associated with less favorable outcome, this study supports the growing evidence for the need of unloading retropatellar cartilage repair, when indicated.

LEVEL OF EVIDENCE

Case series; level of evidence, 4.

Autologous Matrix-Induced Chondrogenesis (AMIC) and Microfractures for Focal Chondral Defects of the Knee: A Medium-Term Comparative Study

Introduction: The potential of autologous matrix-induced chondrogenesis (AMIC) to restore unipolar focal chondral defects of the knee is promising. However, the outcome compared to microfracturing (MFx) for certain defect sizes (2–3 cm²) is still uncertain. Therefore, the present study compared primary isolated AMIC versus MFx in a cohort of patients with borderline sized focal unipolar chondral defects of the knee at midterm follow-up. Methods: Patients with chondral defects of the knee who underwent AMIC or MFx were compared. An arthroscopic approach was used for MFx, and a minimally invasive parapatellar arthrotomy for AMIC. For those patients who underwent AMIC, a collagen membrane was used with fibrin glue. The patients answered independently: Visual Analogic Scale (VAS), Tegner Activity Scale, International Knee Documentation Committee (IKDC), and the Lysholm scores. Results: A total of 83 patients with a mean age of 30.2 and body mass index (BMI) of 26.9 kg/m² were recruited. Of them, 33.7% (28 of 83) were women, and 55.4% (46 of 83 patients) had defects in the right knee. The mean length of symptoms before surgery was 43.3 months. The mean size of the defect was 2.7 cm². The mean length of follow-up was 42.1 months. No difference was found in terms of symptoms and follow-up length, mean age and BMI, mean size of defect, sex, and side. The AMIC cohort reported greater IKCD (p > 0.0001), Lysholm (p = 0.002), VAS (p = 0.01), Tegner (p = 0.004) scores. The AMIC cohort reported lower rate of failure (p = 0.005) and revision surgery (p = 0.02). No difference was found in the rate of arthroplasty (p = 0.2). No delamination or hypertrophy were detected. Conclusion: AMIC demonstrated superiority over MFx for focal unipolar chondral defects of the knee. At approximately 40 months follow-up, the IKDC, Lysholm, and VAS scores were greater in the AMIC group. Patients treated with AMIC also demonstrated a higher level of sport activity, and lower rates of failure and revision surgeries.

Repopulation of decellularised articular cartilage by laser-based matrix engraving

BACKGROUND

In spite of advances in the treatment of cartilage defects using cell and scaffold-based therapeutic strategies, the long-term outcome is still not satisfying since clinical scores decline years after treatment. Scaffold materials currently used in clinical settings have shown limitations in providing suitable biomechanical properties and an authentic and protective environment for regenerative cells. To tackle this problem, we developed a scaffold material based on decellularised human articular cartilage.

METHODS

Human articular cartilage matrix was engraved using a CO₂ laser and treated for decellularisation and glycosaminoglycan removal. Characterisation of the resulting scaffold was performed via mechanical testing, DNA and GAG quantification and in vitro cultivation with adipose-derived stromal cells (ASC). Cell vitality, adhesion and chondrogenic differentiation were assessed. An ectopic, unloaded mouse model was used for the assessment of the in vivo performance of the scaffold in combination with ASC and human as well as bovine chondrocytes. The novel scaffold was compared to a commercial collagen type I/III scaffold.

FINDINGS

Crossed line engravings of the matrix allowed for a most regular and ubiquitous distribution of cells and chemical as well as enzymatic matrix treatment was performed to increase cell adhesion. The biomechanical characteristics of this novel scaffold that we term CartiScaff were found to be superior to those of commercially available materials. Neo-tissue was integrated excellently into the scaffold matrix and new collagen fibres were guided by the laser incisions towards a vertical alignment, a typical feature of native cartilage important for nutrition and biomechanics. In an ectopic, unloaded in vivo model, chondrocytes and mesenchymal stromal cells differentiated within the incisions despite the lack of growth factors and load, indicating a strong chondrogenic microenvironment within the scaffold incisions. Cells, most noticeably bone marrow-derived cells, were able to repopulate the empty chondrocyte lacunae inside the scaffold matrix.

INTERPRETATION

Due to the better load-bearing, its chondrogenic effect and the ability to guide matrix-deposition, CartiScaff is a promising biomaterial to accelerate rehabilitation and to improve long term clinical success of cartilage defect treatment.

FUNDING

Austrian Research Promotion Agency FFG ("CartiScaff" #842455), Lorenz Böhler Fonds (16/13), City of Vienna Competence Team Project Signaltissue (MA23, #18-08).

Repopulation of decellularised articular cartilage by laser-based matrix engraving

Background

In spite of advances in the treatment of cartilage defects using cell and scaffold-based therapeutic strategies, the long-term outcome is still not satisfying since clinical scores decline years after treatment. Scaffold materials currently used in clinical settings have shown limitations in providing suitable biomechanical properties and an authentic and protective environment for regenerative cells. To tackle this problem, we developed a scaffold material based on decellularised human articular cartilage.

Methods

Human articular cartilage matrix was engraved using a CO₂ laser and treated for decellularisation and glycosaminoglycan removal. Characterisation of the resulting scaffold was performed via mechanical testing, DNA and GAG quantification and in vitro cultivation with adipose-derived stromal cells (ASC). Cell vitality, adhesion and chondrogenic differentiation were assessed. An ectopic, unloaded mouse model was used for the assessment of the in vivo performance of the scaffold in combination with ASC and human as well as bovine chondrocytes. The novel scaffold was compared to a commercial collagen type I/III scaffold.

Findings

Crossed line engravings of the matrix allowed for a most regular and ubiquitous distribution of cells and chemical as well as enzymatic matrix treatment was performed to increase cell adhesion. The biomechanical characteristics of this novel scaffold that we term CartiScaff were found to be superior to those of commercially available materials. Neo-tissue was integrated excellently into the scaffold matrix and new collagen fibres were guided by the laser incisions towards a vertical alignment, a typical feature of native cartilage important for nutrition and biomechanics. In an ectopic, unloaded in vivo model, chondrocytes and mesenchymal stromal cells differentiated within the incisions despite the lack of growth factors and load, indicating a strong chondrogenic microenvironment within the scaffold incisions. Cells, most noticeably bone marrow-derived cells, were able to repopulate the empty chondrocyte lacunae inside the scaffold matrix.

Interpretation

Due to the better load-bearing, its chondrogenic effect and the ability to guide matrix-deposition, CartiScaff is a promising biomaterial to accelerate rehabilitation and to improve long term clinical success of cartilage defect treatment.

Funding

Austrian Research Promotion Agency FFG (“CartiScaff” #842455), Lorenz Böhler Fonds (16/13), City of Vienna Competence Team Project Signaltissue (MA23, #18-08)