Arthroscopic assessment of cartilage repair: a validation study of 2 scoring systems

Enhanced osteochondral repair by leukocyte-depleted platelet-rich plasma in combination with adipose-derived mesenchymal stromal cells encapsulated in a three-dimensional photocrosslinked injectable hydrogel in a rabbit model

INTRODUCTION

Intra-articular injection of adipose-derived mesenchymal stromal cells (ASCs) and/or platelet-rich plasma (PRP) have been reported to independently and synergistically improve healing of osteochondral lesions in animal models. However, their independent and combined effects when localized to an osteochondral lesion by encapsulation within a photocrosslinkable methacrylated gelatin hydrogel (GelMA) have not been explored. Herein we investigated a unique combination of allogeneic ASCs and PRP embedded in GelMA as a single-stage treatment for osteochondral regeneration in a rabbit model.

METHODS

Thirty mature rabbits were divided into six experimental groups: (1) Sham; (2) Defect; (3) GelMA; (4) GelMA + ASCs; (5) GelMA + PRP; and (6) GelMA + ASCs + PRP.At 12 weeks following surgical repair, osteochondral regeneration was assessed on the basis of gross appearance, biomechanical properties, histological and immunohistochemical characteristics, and subchondral bone volume.

RESULTS

In terms of mechanical property reflecting the ability of neotissue to bear stress, PRP only group were significantly lower than the Sham group (p = 0.0098). On the other hand, ASCs only and ASCs combined with PRP groups did not exhibit significantly difference, which suggesting that incorporation of ASCs assists in restoring the ability of the neotissue to bear stresses similarly to native tissue (p = 0.346, p = 0.40, respectively). Safranin O in ASCs combined with PRP group was significantly higher than the Defect and GelMA only groups (p = 0.0009, p = 0.0017, respectively). Additionally, ASCs only and ASCs combined with PRP groups presented especially strong staining for collagen type II. Surprisingly, PRP only and PRP + ASCs groups tended to exhibit higher collagen type I and collagen type X staining compared to ASCs only group, suggesting a potential PRP-mediated hypertrophic effect.

CONCLUSION

Regeneration of a focal osteochondral defect in a rabbit model was improved by a single-stage treatment of a photocrosslinked hydrogel containing allogenic ASCs and autologous PRP, with the combination of ASCs and PRP producing superior benefit than either alone. No experimental construct fully restored all properties of the native, healthy osteochondral unit, which may require longer follow-up or further modification of PRP and/or ASCs characteristics.

Prophylaxis and treatment of HIV infection in pregnancy, Swedish guidelines 2024

In May 2024, the Swedish Reference Group on Antiviral Therapy updated the guidelines on management of HIV infection in pregnancy. The most important recommendations and revisions were: (i) ART during pregnancy should be started as early as possible and continue after delivery; (ii) Suppressive ART should normally not be modified; (iii) The treatment target of HIV RNA <20 copies/ml remains; (iv) Dolutegravir/emtricitabine/tenofovir DF is the first-line drug combination also in pregnant women and women planning pregnancy; (v) There is no evidence of an increased risk of neural tube defects associated with dolutegravir; (vi) Mode of delivery for women with effective ART and HIV RNA <200 copies/ml should follow standard obstetric procedures; (vii) Caesarean section is recommended if HIV RNA ≥200 copies/ml; (viii) Scalp electrode, foetal blood sampling and/or vacuum delivery should be used on strict indications, but does not necessitate intensified infant prophylaxis; (ix) Management and mode of delivery in case of premature or full-term rupture of membranes should follow standard obstetric procedures; (x) Recommended infant antiretroviral prophylaxis has been updated; (xi) The duration of infant antiretroviral prophylaxis (gestational age ≥35 weeks and mother on effective ART and HIV RNA <200 copies/ml) has been changed from 4 to 2 weeks; (xii) Infants born to women with HIV RNA ≥200 copies/ml should receive 4 weeks of combination prophylaxis; (xiii) Fertility evaluation and assisted reproduction should be offered to women on suppressive ART according to the same principles as for other women; (xiv) Women living with HIV should still be advised against breastfeeding; (xv) Women who nevertheless opt to breastfeed should be offered intensified support and follow-up.

Improved Outcome With Knee Arthroscopy Relative to Physiotherapy for Symptomatic Unstable Meniscal Tears: 2-Year Prospective Cohort Study

BACKGROUND

Although preservation of meniscal tissue is paramount, there are occasions when repair of a torn meniscus is not possible. The surgical option may be a partial meniscectomy, the objective being to alleviate the patient's symptoms with resection of only that portion of the meniscus that is no longer functioning but is the cause of symptoms. Previous studies have questioned the need to perform such surgery and have recommended nonoperative treatment instead. Our goal was to compare the outcome of partial meniscectomy with that of physiotherapy alone for irreparable meniscal tears.

HYPOTHESIS

Clinical outcome following arthroscopic partial meniscectomy may differ from that following physiotherapy alone, for patients with symptomatic irreparable meniscal tears.

STUDY DESIGN

Nonrandomized prospective cohort study.

LEVEL OF EVIDENCE

Level 2.

METHODS

Patients satisfying the inclusion criteria chose to undergo knee arthroscopy (group A) or physiotherapy (group B). The diagnosis of a meniscal tear was made on physical assessment and magnetic resonance imaging examination. The meniscal tear was preventing them from continuing with their regular weightbearing exercise. Outcomes of interest were the following patient-reported outcomes (PROs): the Knee Osteoarthritis Outcome Score (KOOS) and Tegner Activity Score (TAS), with minimal clinically important differences being 10 and 1, respectively. PROs were completed at baseline, and at 1-year and 2-year follow-up. Changes in scores within and between groups were compared using analysis of variance and Wilcoxon tests (P <0.05). A power analysis demanded 65 patients in each group to produce a power of 80% and a P value of 5%.

RESULTS

Of 528 patients enrolled in the study, 10 were lost to follow-up and 8 were excluded. Data were complete for 269 in group A, and 228 in Group B. Group A and B were similar in terms of age (41.1 years, SD 7.8 vs 40 years, SD 13.3), body mass index (22.5 kg/m2, SD 3.1 vs 23.1 kg/m2, SD 2.3), radiographic grade of osteoarthritis (median grade 2, range 0-3 in both groups), gender (male:female = 134:135 vs 112:116), and duration of symptoms (44.4 days, SD 5.6 vs 46.6 days, SD 8.8), with P >0.05. At both 1-year and 2-year follow-up, Group A had higher scores in the mean total KOOS (88.8, SD 8.0 vs 72.4, SD 3.8), as well as in all subscales within the KOOS, and the TAS (median 7, range 5-9 vs median 5, range 3-6), with P <0.001 for each variable.

CONCLUSION

Performing a knee arthroscopy with partial meniscectomy is associated with improved KOOS and TAS, relative to treatment with physiotherapy alone, at 2-year follow-up.

CLINICAL RELEVANCE

Physically active patients with symptomatic irreparable meniscal tears may experience a better clinical outcome following knee arthroscopy, relative to to physiotherapy alone.

Cytokine Receptor-like Factor 1 (CRLF1) and Its Role in Osteochondral Repair

BACKGROUND

Since cytokine receptor-like factor 1 (CRLF1) has been implicated in tissue regeneration, we hypothesized that CRLF1 released by mesenchymal stem cells can promote the repair of osteochondral defects.

METHODS

The degree of a femoral osteochondral defect repair in rabbits after intra-articular injections of bone marrow-derived mesenchymal stem cells (BMSCs) that were transduced with empty adeno-associated virus (AAV) or AAV containing CRLF1 was determined by morphological, histological, and micro computer tomography (CT) analyses. The effects of CRLF1 on chondrogenic differentiation of BMSCs or catabolic events of interleukin-1beta-treated chondrocyte cell line TC28a2 were determined by alcian blue staining, gene expression levels of cartilage and catabolic marker genes using real-time PCR analysis, and immunoblot analysis of Smad2/3 and STAT3 signaling.

RESULTS

Intra-articular injections of BMSCs overexpressing CRLF1 markedly improved repair of a rabbit femoral osteochondral defect. Overexpression of CRLF1 in BMSCs resulted in the release of a homodimeric CRLF1 complex that stimulated chondrogenic differentiation of BMSCs via enhancing Smad2/3 signaling, whereas the suppression of CRLF1 expression inhibited chondrogenic differentiation. In addition, CRLF1 inhibited catabolic events in TC28a2 cells cultured in an inflammatory environment, while a heterodimeric complex of CRLF1 and cardiotrophin-like Cytokine (CLC) stimulated catabolic events via STAT3 activation.

CONCLUSION

A homodimeric CRLF1 complex released by BMSCs enhanced the repair of osteochondral defects via the inhibition of catabolic events in chondrocytes and the stimulation of chondrogenic differentiation of precursor cells.

The Role of Hyaluronan/Receptor for Hyaluronan-Mediated Motility Interactions in the Modulation of Macrophage Polarization and Cartilage Repair

Hyaluronan (HA), a negatively charged linear glycosaminoglycan, is a key macromolecular component of the articular cartilage extracellular matrix. The differential effects of HA are determined by a spatially/temporally regulated display of HA receptors, such as CD44 and receptor for hyaluronan-mediated motility (RHAMM). HA signaling through CD44 with RHAMM has been shown to stimulate inflammation and fibrotic processes. This study shows an increased expression of RHAMM in proinflammatory macrophages. Interfering with HA/RHAMM interactions using a 15-mer RHAMM-mimetic, HA-binding peptide, together with high-molecular-weight (HMW) HA reduced the expression and release of inflammatory markers and increased the expression of anti-inflammatory markers in proinflammatory macrophages. Interfering with HA/RHAMM interactions in vivo during the regeneration of a full-thickness cartilage defect after microfracture surgery in rabbits using three intra-articular injections of 15-mer RHAMM-mimetic, HA-binding peptide together with HMWHA reduced the number of proinflammatory macrophages and increased the number of anti-inflammatory macrophages in the injured knee joint and greatly improved the repair of the cartilage defect compared with intra-articular injections of HMWHA alone. These findings suggest that HA/RHAMM interactions play a key role in cartilage repair/regeneration via stimulating inflammatory and fibrotic events, including increasing the ratio of proinflammatory/anti-inflammatory macrophages. Interfering with these interactions reduced inflammation and greatly improved cartilage repair.

Comparative Efficacy of Endogenous Stem Cells Recruiting Hydrogels and Stem Cell-loaded Hydrogels in Knee Cartilage Regeneration: A Meta- analysis

BACKGROUND

Cartilage defects remain a challenge in diseases such as osteoarthritis (OA) and fractures. Scientists have explored the use of hydrogels in conjunction with stem cell technology as a tissue engineering method to treat cartilage defects in joints. In recent years, research into hydrogels containing stem cell technology for cartilage repair has mainly focused on two categories: stem cell-loaded hydrogels and endogenous stem cell recruiting hydrogels. The latter, utilizing cell-free products, represents a novel concept with several advantages, including easier dose standardization, wider sources, and simpler storage. This meta-analysis aims to assess and compare the therapeutic effects of endogenous stem cell recruiting hydrogels and stem cell-loaded hydrogels in promoting articular cartilage regeneration in animal models, with the goal of exploring endogenous stem cell recruiting hydrogels as a promising replacement therapy for knee cartilage regeneration in preclinical animal studies.

METHODS

We systematically searched PubMed, Web of Science, Cochrane Library, and Embase until January 2023 using key words related to stem cells, cartilage regeneration and hydrogel. A random-effects meta-analysis was performed to evaluate the therapeutic effect on newborn cartilage formation. Stratified analyses were also carried out by independently classifying trials according to similar characteristics. The level of evidence was determined using the GRADE method.

RESULTS

Twenty-eight studies satisfied the inclusion criteria. Comprehensive analyses revealed that the use of endogenous stem cell recruiting hydrogels significantly promoted the formation of new cartilage in the knee joint, as evidenced by the histological score (3.77, 95% CI 2.40, 5.15; p < 0.0001) and the International Cartilage Repair Society (ICRS) macroscopic score (3.00, 95% CI 1.83, 4.18; p = 0.04), compared with the control group. The stem cell-loaded hydrogels also increased cartilage regeneration in the knee with the histological score (3.13, 95% CI 2.22, 4.04; p = 0.02) and the ICRS macroscopic score (2.49, 95% CI 1.16, 3.82; p = 0.03) in comparison to the control. Significant heterogeneity between studies was observed, and further stratified and sensitivity analyses identified the transplant site and modelling method as the sources of heterogeneity.

CONCLUSION

The current study indicates that both endogenous stem cell recruiting hydrogels and stem cell loaded hydrogels can effectively promote knee joint cartilage regeneration in animal trials.

Atelocollagen-associated autologous chondrocyte implantation for the repair of large cartilage defects of the knee: Results at three to seven years

BACKGROUND

Recently, various types of engineered autologous chondrocyte implantation (ACI) have been developed. Atelocollagen-associated ACI (A-ACI) is the only ACI procedure covered by Japanese Health Insurance since 2013. The indications of the A-ACI are traumatic cartilage defects and osteochondral dissecans (OCD) for knee joints.

PURPOSE

To evaluate midterm clinical results after A-ACI for the treatment for full-thickness cartilage defects of the knee.

METHODS

Thirteen consecutive patients who underwent A-ACI between 2014 and 2018 had been prospectively enrolled in this study. There were 11 men and 2 women with a mean age of 34 years at the time of surgery. The causes of the cartilage defect were trauma in 10 knees and OCD in 3 knees. The total number of lesions was 15, which were comprised of the medial femoral condyle in 5 knees, the lateral femoral condyle in 5 knees, and the femoral trochlea in 5 knees. The mean size of the lesion was 5.3 cm2. Each knee was clinically and radiologically evaluated preoperatively and postoperatively.

RESULTS

The mean Lysholm score improved significantly from 74.0 points to 94.0 points (p = 0.008) and each subscale in Knee injury and Osteoarthritis Outcome Score improved significantly (p < 0.001) at the mean final follow-up period of 51 months (range, 36-84 months). The magnetic resonance observation of cartilage repair tissue 2.0 score at the mean follow-up of 38 months was significantly higher than that at 2 months postoperatively (p = 0.014). According to the International Cartilage Repair Society (ICRS) grading scale, 3 knees were graded as normal, 3 knees as nearly normal, and 1 knee as severely abnormal in second-look arthroscopic evaluation at a mean of 22 months (range, 8-41 months) after A-ACI.

CONCLUSION

The present study showed a significant subjective and objective clinical improvement in the A-ACI for large cartilage defects of the knee at a mean follow-up of 51 months (range, 36-84 months).

Comprehensive Study on Scoring and Grading Systems for Predicting the Severity of Knee Osteoarthritis

Knee Osteoarthritis (KOA) is a degenerative joint ailment characterized by cartilage loss, which can be seen using imaging modalities and converted into imaging features. The older population is the most affected by knee OA, which affects 16% of people worldwide who are 15 years of age and older. Due to cartilage tissue degradation, primary knee OA develops in older people. In contrast, joint overuse or trauma in younger people can cause secondary knee OA. Early identification of knee OA, according to research, may be a successful management tactic for the condition. Scoring scales and grading systems are important tools for the management of knee osteoarthritis as they allow clinicians to measure the progression of the disease's severity and provide suggestions on suitable treatment at identified stages. The comprehensive study reviews various subjective and objective knee evaluation scoring systems that effectively score and grade the KOA based on where defects or changes in articular cartilage occur. Recent studies reveal that AI-based approaches, such as that of DenseNet, integrating the concept of deep learning for scoring and grading the KOA, outperform various state-of-the-art methods in order to predict the KOA at an early stage.

A New Bioactive Fibrin Formulation Provided Superior Cartilage Regeneration in a Caprine Model

The effective and long-term treatment of cartilage defects is an unmet need among patients worldwide. In the past, several synthetic and natural biomaterials have been designed to support functional articular cartilage formation. However, they have mostly failed to enhance the terminal stage of chondrogenic differentiation, leading to scar tissue formation after the operation. Growth factors substantially regulate cartilage regeneration by acting on receptors to trigger intracellular signaling and cell recruitment for tissue regeneration. In this study, we investigated the effect of recombinant insulin-like growth factor 1 (rIGF-1), loaded in fibrin microbeads (FibIGF1), on cartilage regeneration. rIGF-1-loaded fibrin microbeads were injected into full-thickness cartilage defects in the knees of goats. The stability, integration, and quality of tissue repair were evaluated at 1 and 6 months by gross morphology, histology, and collagen type II staining. The in vivo results showed that compared to plain fibrin samples, particularly at 6 months, FibIGF1 improved the functional cartilage formation, confirmed through gross morphology, histology, and collagen type II immunostaining. FibIGF1 could be a promising candidate for cartilage repair in the clinic.

A Multi-Disciplinary MRI Assessment May Optimize the Evaluation of Chondral Lesions in Acute Ankle Fractures: A Prospective Study

Chondral lesions (CL) in the ankle following acute fractures are frequently overlooked immediately after the injury or diagnosed at a later stage, leading to persistent symptoms despite successful surgery. The literature presents a wide range of discrepancies in the reported incidence of CLs in acute ankle fractures. The objective of this prospective study is to provide a precise assessment of the occurrence of chondral lesions (CLs) in acute ankle fractures through MRI scans conducted immediately after the trauma and prior to scheduled surgery. Furthermore, the study aims to highlight the disparities in the interpretation of these MRI scans, particularly concerning the size and extent of chondral damage, between radiologists and orthopedic surgeons. Over the period of three years, all patients presenting with an unstable ankle fracture that underwent operative treatment were consecutively included in this single-center prospective study. Preoperative MRIs were obtained for all included patients within 10 days of the trauma and were evaluated by a trauma surgeon and a radiologist specialized in musculoskeletal MRI blinded to each other's results. The location of the lesions was documented, as well as their size and ICRS classification. Correlations and kappa coefficients as well as the p-values were calculated. A total of 65 patients were included, with a mean age of 41 years. The evaluation of the orthopedic surgeon showed CLs in 52.3% of patients. CLs occurred mainly on the tibial articular surface (70.6%). Most talar lesions were located laterally (11.2%). The observed CLs were mainly ICRS grade 4. According to the radiologist, 69.2% of the patients presented with CLs. The most common location was the talar dome (48.9%), especially laterally. Most detected CLs were graded ICRS 3a. The correlation between the two observers was weak/fair regarding the detection and classification of CLs and moderate regarding the size of the detected CLs. To enhance the planning of surgical treatment for ankle chondral lesions (CLs), it may be beneficial to conduct an interdisciplinary preoperative assessment of the performed scans. This collaborative approach can optimize the evaluation of ankle CLs and improve overall treatment strategies.

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.

Favourable clinical, arthroscopic and radiographic outcomes after autologous osteoperiosteal transplantation for massive medial cystic osteochondral defects of the talus

PURPOSE

The purpose of this study was to retrospectively evaluate the clinical, arthroscopic and radiological outcomes of autologous osteoperiosteal transplantation for massive cystic osteochondral defects of the talus.

METHODS

Cases of autologous osteoperiosteal transplantation for medial massive cystic defects of the talus between 2014 and 2018 were reviewed. The visual analogue scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) score, Foot and Ankle Outcome Score (FAOS), and Ankle Activity Scale (AAS) were assessed preoperatively and postoperatively. The Magnetic Resonance Observation of Cartilage Tissue (MOCART) system and the International Cartilage Repair Society (ICRS) score were evaluated after surgery. The ability to return to daily activity and sport, as well as complications, were recorded.

RESULTS

Twenty-one patients were available for follow-up, with a mean follow-up of 60.1 ± 11.7 months. All subscales of preoperative FAOS had significant (P < 0.001) improvement at the final follow-up. The mean AOFAS and VAS scores significantly (P < 0.001) improved from 52.4 ± 12.4 preoperatively to 90.9 ± 5.2 at the last follow-up and from 7.9 ± 0.8 to 1.5 ± 0.9, respectively. The mean AAS decreased from 6.0 ± 1.4 preinjury to 1.4 ± 0.9 postinjury and then increased to 4.6 ± 1.4 at the final follow-up (P < 0.001). All 21 patients resumed daily activities after a mean of 3.1 ± 1.0 months. Fifteen patients (71.4%) returned to sports after a mean of 12.9 ± 4.1 months. All patients underwent follow-up MRI with a mean MOCART score of 68.6 ± 5.9. Eleven patients underwent second-look arthroscopy, and the average ICRS was 9.4 ± 0.8. No donor site morbidity was found in any patient during the follow-up.

CONCLUSION

Autologous osteoperiosteal transplantation provided favourable clinical, arthroscopic and radiographic outcomes in patients with massive cystic osteochondral defects of the talus during a minimum 3-year follow-up.

LEVEL OF EVIDENCE

IV.

Histological and Radiological Assessment of Endogenously Generated Repair Tissue In Vivo Following a Chondral Harvest

OBJECTIVE

To examine repair tissue formed approximately 15 months after a chondral harvest in the human knee.

DESIGN

Sixteen individuals (12 males, 4 females, mean age 36 ± 9 years) underwent a chondral harvest in the trochlea as a pre-requisite for autologous chondrocyte implantation (ACI) treatment. The harvest site was assessed via MRI at 14.3 ± 3.2 months and arthroscopy at 15 ± 3.5 months (using the Oswestry Arthroscopy Score [O-AS] and the International Cartilage Repair Society Arthroscopy Score [ICRS-AS]). Core biopsies (1.8 mm diameter, n = 16) of repair tissue obtained at arthroscopy were assessed histologically (using the ICRS II and OsScore histology scores) and examined via immunohistochemistry for the presence of collagen types I and II.

RESULTS

The mean O-AS and ICRS-AS of the repaired harvest sites were 7.2 ± 3.2 and 10.1 ± 3.5, respectively, with 80.3% ± 26% repair fill depth on MRI. The histological quality of the repair tissue formed was variable, with some hyaline cartilage present in 50% of the biopsies; where this occurred, it was associated with a significantly higher ICRS-AS than those with no hyaline cartilage present (median 11 vs. 7.5, P = 0.049). Collagen types I and II were detected in 12/14 and 10/13 biopsies, respectively.

CONCLUSIONS

We demonstrate good-quality structural repair tissue formed following cartilage harvest in ACI, suggesting this site can be useful to study endogenous cartilage repair in humans. The trochlea is less commonly affected by osteoarthritis; therefore, location may be critical for spontaneous repair. Understanding the mechanisms and factors influencing this could improve future treatments for cartilage defects.

Within or Without You? A Perspective Comparing In Situ and Ex Situ Tissue Engineering Strategies for Articular Cartilage Repair

Human articular cartilage has a poor ability to self-repair, meaning small injuries often lead to osteoarthritis, a painful and debilitating condition which is a major contributor to the global burden of disease. Existing clinical strategies generally do not regenerate hyaline type cartilage, motivating research toward tissue engineering solutions. Prospective cartilage tissue engineering therapies can be placed into two broad categories: i) Ex situ strategies, where cartilage tissue constructs are engineered in the lab prior to implantation and ii) in situ strategies, where cells and/or a bioscaffold are delivered to the defect site to stimulate chondral repair directly. While commonalities exist between these two approaches, the core point of distinction-whether chondrogenesis primarily occurs "within" or "without" (outside) the body-can dictate many aspects of the treatment. This difference influences decisions around cell selection, the biomaterials formulation and the surgical implantation procedure, the processes of tissue integration and maturation, as well as, the prospects for regulatory clearance and clinical translation. Here, ex situ and in situ cartilage engineering strategies are compared: Highlighting their respective challenges, opportunities, and prospects on their translational pathways toward long term human cartilage repair.

In Situ Assessment of Porcine Osteochondral Repair Tissue in the Visible-Near Infrared Spectral Region

Standard assessment of cartilage repair progression by visual arthroscopy can be subjective and may result in suboptimal evaluation. Visible-near infrared (Vis-NIR) fiber optic spectroscopy of joint tissues, including articular cartilage and subchondral bone, provides an objective approach for quantitative assessment of tissue composition. Here, we applied this technique in the 350-2,500 nm spectral region to identify spectral markers of osteochondral tissue during repair with the overarching goal of developing a new approach to monitor repair of cartilage defects in vivo. Full thickness chondral defects were created in Yucatan minipigs using a 5-mm biopsy punch, and microfracture (MFx) was performed as a standard technique to facilitate repair. Tissues were evaluated at 1 month (in adult pigs) and 3 months (in juvenile pigs) post-surgery by spectroscopy and histology. After euthanasia, Vis-NIR spectra were collected in situ from the defect region. Additional spectroscopy experiments were carried out in vitro to aid in spectral interpretation. Osteochondral tissues were dissected from the joint and evaluated using the conventional International Cartilage Repair Society (ICRS) II histological scoring system, which showed lower scores for the 1-month than the 3-month repair tissues. In the visible spectral region, hemoglobin absorbances at 540 and 570 nm were significantly higher in spectra from 1-month repair tissue than 3-month repair tissue, indicating a reduction of blood in the more mature repair tissue. In the NIR region, we observed qualitative differences between the two groups in spectra taken from the defect, but differences did not reach significance. Furthermore, spectral data also indicated that the hydrated environment of the joint tissue may interfere with evaluation of tissue water absorbances in the NIR region. Together, these data provide support for further investigation of the visible spectral region for assessment of longitudinal repair of cartilage defects, which would enable assessment during routine arthroscopy, particularly in a hydrated environment.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

II, systematic review of Levels I-II studies.

Umbilical Cord-Derived Stem Cells for the Treatment of Knee Osteoarthritis: A Systematic Review

Background:

The use of mesenchymal stem cells (MSCs) for the treatment of knee osteoarthritis (OA) has gained recent interest in the orthopaedics community.

Purpose:

To review the literature to evaluate the efficacy of umbilical cord–derived MSCs in the treatment of OA of the knee joint.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

We searched the PubMed, Cochrane Library, and Embase databases to identify studies with evidence levels from 1 to 4 that evaluated the clinical efficacy of human umbilical cord–derived MSC (hUC-MSC) injections for knee OA. The search phrase used was “umbilical cord knee osteoarthritis.” In the studies reviewed, patients were assessed based on the macroscopic International Cartilage Regeneration & Joint Preservation Society (ICRS) score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), visual analog scale (VAS) for pain, and the subjective International Knee Documentation Committee (IKDC) score.

Results:

A total of 7 studies met inclusion criteria, including 385 patients undergoing injection of hUC-MSCs (mean age, 59.7 years). The mean follow-up was 23.4 months. Weighted averages of the WOMAC, macroscopic ICRS, subjective IKDC, and VAS scores all showed improvement from before to after treatment. No severe adverse reactions were recorded.

Conclusion:

Patients undergoing treatment of knee OA with hUC-MSCs might be expected to experience improvements in clinical outcomes. Additional high-quality randomized studies are needed to better determine the efficacy of hUC-MSC for the treatment of knee OA.

Outcome-Affecting Parameters of Hip Arthroscopy for Femoroacetabular Impingement with Concomitant Cartilage Damage-Data Analysis from the German Cartilage Registry

This study aims to report on a prospectively collected, multicenter database of patients undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAI) and concomitant cartilage damage (according to the International Cartilage Repair Society) and to assess the outcome-affecting parameters. In the study, 353 hips with up to 24 months’ follow-up were assessed by iHOT-33 scoring and achievement of the minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) levels. Multiple and binary regression analyses were performed to identify factors related to (un-) favorable outcomes and to assess their clinical relevance with regard to achieving the MCID and PASS. Multiple regression yielded the parameters of male sex (p = 0.022) and lower body mass index (BMI) (p = 0.019) at 6 months, lower BMI (p = 0.022) and younger age (p = 0.022) at 12 months, and younger age at 24 months (p = 0.039) to be significantly associated with higher iHOT scoring. Male sex (p = 0.019) and lower BMI (p = 0.018) were significantly correlated with achievement of the PASS in binary regression at 6 months, whereas at 12 (p = 0.010) and at 24 (p = 0.003) only younger age was shown to be significantly correlated. None of the parameters was statistically associated with achievement of the MCID. As the parameters of younger age, male sex, and lower BMI were identified as temporarily correlated with a preferable outcome in general and with achievement of the PASS in particular, these findings help to preoperatively identify factors associated with (un-) favorable therapy results.

Mesenchymal Stem Cell Exosomes Promote Functional Osteochondral Repair in a Clinically Relevant Porcine Model

BACKGROUND

Previous studies have reported the efficacy of human mesenchymal stem cell (MSC) exosomes for the repair of osteochondral defects in rats and rabbits. However, the safety and efficacy of MSC exosomes remain to be validated in a clinically relevant large animal model.

PURPOSE

To validate the safety and efficacy of human MSC exosomes for osteochondral repair in a clinically relevant micropig model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Bilateral osteochondral defects (6-mm diameter and 1-mm depth) were surgically created in the medial femoral condyles in knees of 12 micropigs. The pigs then received 2-mL intra-articular injections of MSC exosomes and hyaluronic acid (HA) (Exosome+HA) or HA alone after surgery and thereafter at 8 and 15 days. Osteochondral repair was assessed by magnetic resonance imaging (MRI) at 15 days and at 2 and 4 months after surgery as well as by macroscopic, histological, biomechanical, and micro-computed tomography (micro-CT) analyses at 4 months after surgery.

RESULTS

Exosome+HA-treated defects demonstrated significantly better MRI scores than HA-treated defects at 15 days and at 2 and 4 months. Additionally, Exosome+HA-treated defects demonstrated functional cartilage and subchondral bone repair, with significantly better macroscopic and histological scores and biomechanical properties (Young modulus and stiffness) than HA-treated defects at 4 months. Micro-CT further showed significantly higher bone volume and trabecular thickness in the subchondral bone of Exosome+HA-treated defects than that of HA-treated defects. Importantly, no adverse response or major systemic alteration was observed in any of the animals.

CONCLUSION

This study shows that the combination of MSC exosomes and HA administered at a clinically acceptable frequency of 3 weekly intra-articular injections can promote functional cartilage and subchondral bone repair, with significantly improved morphological, histological, and biomechanical outcomes in a clinically relevant porcine model.

CLINICAL RELEVANCE

Our findings provide a robust scientific rationale to support a phase 1/2 clinical trial to test MSC exosomes in patients with osteochondral lesions.

Comparison Between Arthroscopic and Histological International Cartilage Repair Society Scoring Systems in Porcine Cartilage Repair Model

OBJECTIVE

The arthroscopic and histological International Cartilage Repair Society (ICRS) scores are designed to evaluate cartilage repair quality. Arthroscopic ICRS score can give a maximum score of 12 and the histological score can give values between 0% and 100% for each of its 14 subscores. This study compares these methods in an animal cartilage repair model. This study hypothesizes that there is a significant correlation between these methods.

DESIGN

A chondral defect was made in the medial femoral condyle of 18 pigs. Five weeks later, 9 pigs were treated with a novel recombinant human type III collagen/polylactide scaffold and 9 were left untreated to heal spontaneously. After 4 months, the medial condyles were evaluated with a simulated arthroscopy using the ICRS scoring system followed by a histological ICRS scoring.

RESULTS

This porcine cartilage repair model produced repaired cartilage tissue ranging from good to poor repair tissue quality. The mean arthroscopic ICRS total score was 6.8 (SD = 2.2). Histological ICRS overall assessment subscore was 38.2 (SD = 31.1) and histological ICRS average points were 60.5 (SD = 19.5). Arthroscopic ICRS compared with histological ICRS average points or its overall assessment subscore showed moderate correlation (r = 0.49 and r = 0.50, respectively). The interrater reliability with the intraclass correlation coefficients for arthroscopic ICRS total scores, histological ICRS overall assessment subscore, and ICRS average points showed moderate to excellent reliability.

CONCLUSIONS

Arthroscopic and histological ICRS scoring methods for repaired articular cartilage show a moderate correlation in the animal cartilage repair model.

Biomechanical Changes of Repair Tissue after Autologous Chondrocyte Implantation at Long-Term Follow-Up

Objective. This study aims to describe biomechanical maturation process of repair tissue after cartilage repair with autologous chondrocyte implantation (ACI) at long-term follow-up. Design. After ACI, 40 patients underwent altogether 60 arthroscopic biomechanical measurements of the repair tissue at various time points during an up to 11-year follow-up period. Of these patients, 30 patients had full-thickness cartilage lesions and 10 had an osteochondritis dissecans (OCD) defect. The mean lesion area was 6.5 cm² (SD 3.2). A relative indentation stiffness value for each individually measured lesion was calculated as a ratio of repair tissue and surrounding cartilage indentation value to enable interindividual comparison. Results. Repair tissue stiffness improved during approximately 5 years after surgery. Most of the increase in stiffness occurred during the first 2 years. The curvilinear correlation between relative stiffness values and the follow-up time was 0.31 (95% CI 0.07-0.52), P = 0.017. The interindividual variation of the stiffness was high. Lesion properties or demographic factors showed no significant correlation to biomechanical outcome. The overall postoperative average relative stiffness was 0.75 (SD 0.47). Conclusions. Our clinical study describes a biomechanical maturation process of cartilage repair that may continue even longer than expected. A substantial increase in tissue stiffness proceeds for the first two years postoperatively. Minor progression proceeds for even longer. In some repairs, the biomechanical result was equal to native cartilage, suggesting hyaline-type repair. The variation in biomechanical results suggests substantial inconsistency in the structural outcome following ACI.

Resorbable Pins to Enhance Scaffold Retention in a Porcine Chondral Defect Model

OBJECTIVE

Cartilage repair strategies have seen improvement in recent years, especially with the use of scaffolds that serve as a template for cartilage formation. However, current fixation strategies are inconsistent with regards to retention, may be technically challenging, or may damage adjacent tissues or the implant itself. Therefore, the goal of this study was to evaluate the retention and repair potential of cartilage scaffolds fixed with an easy-to-implement bioresorbable pin.

DESIGN

Electrospun hyaluronic acid scaffolds were implanted into trochlear groove defects in 3 juvenile and 3 adult pigs to evaluate short-term retention (2 weeks; pin fixation vs. press-fit and fibrin fixation) and long-term repair (8 months; scaffold vs. microfracture), respectively.

RESULTS

For the retention study, press-fit and fibrin fixation resulted in short-term scaffold dislodgment (n = 2 each), whereas pin fixation retained all scaffolds that were implanted (n = 6). Pin fixation did not cause any damage to the opposing patellar surface, and only minor changes in the subchondral bone were observed. For long-term repair, no differences were observed between microfracture and scaffold groups, in terms of second-look arthroscopy and indentation testing. On closer visualization with micro computed tomography and histology, a high degree of variability was observed between animals with regard to subchondral bone changes and cartilage repair quality, yet each Scaffold repair displayed similar properties to its matched microfracture control.

CONCLUSIONS

In this study, pin fixation did not cause adverse events in either the short- or the long-term relative to controls, indicating that pin fixation successfully retained scaffolds within defects without inhibiting repair.

Tetrahedral framework nucleic acids promote the biological functions and related mechanism of synovium-derived mesenchymal stem cells and show improved articular cartilage regeneration activity in situ

Many recent studies have shown that joint-resident mesenchymal stem cells (MSCs) play a vital role in articular cartilage (AC) in situ regeneration. Specifically, synovium-derived MSCs (SMSCs), which have strong chondrogenic differentiation potential, may be the main driver of cartilage repair. However, both the insufficient number of MSCs and the lack of an ideal regenerative microenvironment in the defect area will seriously affect the regeneration of AC. Tetrahedral framework nucleic acids (tFNAs), notable novel nanomaterials, are considered prospective biological regulators in biomedical engineering. Here, we aimed to explore whether tFNAs have positive effects on AC in situ regeneration and to investigate the related mechanism. The results of in vitro experiments showed that the proliferation and migration of SMSCs were significantly enhanced by tFNAs. In addition, tFNAs, which were added to chondrogenic induction medium, were shown to promote the chondrogenic capacity of SMSCs by increasing the phosphorylation of Smad2/3. In animal models, the injection of tFNAs improved the therapeutic outcome of cartilage defects compared with that of the control treatments without tFNAs. In conclusion, this is the first report to demonstrate that tFNAs can promote the chondrogenic differentiation of SMSCs in vitro and enhance AC regeneration in vivo, indicating that tFNAs may become a promising therapeutic for AC regeneration.

•

Tetrahedral framework nucleic acids (tFNAs) can promote SMSCs proliferation by activating the Wnt/β-catenin pathway.

•

tFNAs can promote SMSCs migration in vitro and vivo.

•

tFNAs can promote SMSCs chondrogenic differentiation by regulating the TGF/Smad2/3 signaling pathway.

•

tFNAs show improved articular cartilage in situ regeneration activity in vivo.

Bilayered scaffold with 3D printed stiff subchondral bony compartment to provide constant mechanical support for long-term cartilage regeneration

BACKGROUND/OBJECTIVE

We seek to figure out the effect of stable and powerful mechanical microenvironment provided by Ti alloy as a part of subchondral bone scaffold on long-term cartilage regeneration.Methods: we developed a bilayered osteochondral scaffold based on the assumption that a stiff subchondral bony compartment would provide stable mechanical support for cartilage regeneration and enhance subchondral bone regeneration. The subchondral bony compartment was prepared from 3D printed Ti alloy, and the cartilage compartment was created from a freeze-dried collagen sponge, which was reinforced by poly-lactic-co-glycolic acid (PLGA).

RESULTS

In vitro evaluations confirmed the biocompatibility of the scaffold materials, while in vivo evaluations demonstrated that the mechanical support provided by 3D printed Ti alloy layer plays an important role in the long-term regeneration of cartilage by accelerating osteochondral formation and its integration with the adjacent host tissue in osteochondral defect model at rabbit femoral trochlea after 24 weeks.

CONCLUSION

Mechanical support provided by 3D printing Ti alloy promotes cartilage regeneration by promoting subchondral bone regeneration and providing mechanical support platform for cartilage synergistically.

TRANSLATIONAL POTENTIAL STATEMENT

The raw materials used in our double-layer osteochondral scaffolds are all FDA approved materials for clinical use. 3D printed titanium alloy scaffolds can promote bone regeneration and provide mechanical support for cartilage regeneration, which is very suitable for clinical scenes of osteochondral defects. In fact, we are conducting clinical trials based on our scaffolds. We believe that in the near future, the scaffold we designed and developed can be formally applied in clinical practice.

Importance of patellofemoral and tibiofemoral cartilage lesions on trajectory of self-reported outcomes in patients at high risk of knee OA: 4-6 years follow-up of patients undergoing meniscal surgery

OBJECTIVE

We evaluated whether patient-reported outcome trajectories (i.e., changes over time) differed by intraoperative compartmental cartilage lesion pattern over 4-6 years following arthroscopic meniscal surgery.

METHODS

In this ancillary study of the Knee Arthroscopy Cohort Southern Denmark cohort, we intraoperatively categorized cartilage lesions as isolated patellofemoral, isolated tibiofemoral, or combined patellofemoral/tibiofemoral. Participants completed the Knee injury and Osteoarthritis Outcome Score (KOOS) pre-operatively, at 3 and 12 months, and at 4-6 years post-operatively and reported overall satisfaction at final follow-up. Our main outcome was KOOS₄ (grand mean of four subscale means). We evaluated whether KOOS₄ scores changed over time according to cartilage lesion patterns using adjusted mixed linear regression. We also estimated probability of treatment satisfaction using logistic regression.

RESULTS

Of 630 participants with complete cartilage scores, 280 (44%) were women, mean (standard deviation) age was 49 (13) years, and BMI was 27.3 (4.4) kg/m². KOOS₄ scores at baseline were slightly lower in all lesion groups compared to the no lesion group, yet only the combined group was statistically significantly lower. KOOS₄ trajectories were similar across cartilage lesion patterns, but by final follow-up, adjusted mean KOOS₄ scores were 6.8 (95% CI 2.2, 11.4) to 9.8 (1.1, 18.5) points lower in groups with cartilage lesions compared to the no lesion group. Probability of patient-reported satisfaction did not differ statistically by group.

CONCLUSIONS

Though KOOS₄ scores were slightly lower in groups with arthroscopically assessed cartilage lesions compared to the no lesion group, trajectories were similar across all groups.

Identifying Consensus and Open Questions around Assessing or Predicting the Quality and Success of Cartilage Repair: A Delphi Study

A range of surgical techniques have been developed for the repair or regeneration of lesioned cartilage in the human knee and a corresponding array of scoring systems have been created to assess their outcomes. The published literature displays a wide range of opinions regarding the factors that influence the success of surgical cartilage repair and which parameters are the most useful for measuring the quality of the repair at follow-up. Our objective was to provide some clarity to the field by collating items that were agreed upon by a panel of experts to be important in these areas. A modified, three-round Delphi consensus study was carried out consisting of one idea-generating focus-group and two subsequent, self-completed questionnaire rounds. In each round, items were assessed for their importance and level of consensus against pre-determined threshold levels. In total, 31 items reached consensus, including a hierarchy of tissues in the joint based on their importance in cartilage repair, markers of repair cartilage quality and the implications of environmental and patient-related factors. Items were stratified into those that can be employed for predicting the success of cartilage repair and those that could be used for assessing the structural quality of the resulting repair cartilage. Items that did not reach consensus represent areas where dissent remains and could, therefore, be used to guide future clinical and fundamental scientific research.

Arthroscopic International Cartilage Repair Society Classification System Has Only Moderate Reliability in a Porcine Cartilage Repair Model

BACKGROUND

The International Cartilage Repair Society (ICRS) score was designed for arthroscopic use to evaluate the quality of cartilage repair.

PURPOSE

To evaluate the reliability of the ICRS scoring system using an animal cartilage repair model.

STUDY DESIGN

Controlled laboratory study.

METHODS

A chondral defect with an area of 1.5 cm² was made in the medial femoral condyle of 18 domestic pigs. Five weeks later, 9 pigs were treated using a novel recombinant human type III collagen/polylactide scaffold, and 9 were left to heal spontaneously. After 4 months, the pigs were sacrificed, then 3 arthroscopic surgeons evaluated the medial femoral condyles via video-recorded simulated arthroscopy using the ICRS scoring system. The surgeons repeated the evaluation twice within a 9-month period using their recorded arthroscopy.

RESULTS

The porcine cartilage repair model produced cartilage repair tissue of poor to good quality. The mean ICRS total scores for all observations were 6.6 (SD, 2.6) in arthroscopy, 5.9 (SD, 2.7) in the first reevaluation, and 6.2 (SD, 2.8) in the second reevaluation. The interrater reliability with the intraclass correlation coefficient (ICC) for the ICRS total scores (ICC, 0.46-0.60) and for each individual subscore (ICC, 0.26-0.71) showed poor to moderate reliability. The intrarater reliability with the ICC also showed poor to moderate reliability for ICRS total scores (ICC, 0.52-0.59) and for each individual subscore (ICC, 0.29-0.58). A modified Bland-Altman plot for the initial arthroscopy and for the 2 reevaluations showed an evident disagreement among the observers.

CONCLUSION

In an animal cartilage repair model, the ICRS scoring system seems to have poor to moderate reliability.

CLINICAL RELEVANCE

Arthroscopic assessment of cartilage repair using the ICRS scoring method has limited reliability. We need more objective methods with acceptable reliability to evaluate cartilage repair outcomes.

Nanofibrous hyaluronic acid scaffolds delivering TGF-β3 and SDF-1α for articular cartilage repair in a large animal model

Focal cartilage injuries have poor intrinsic healing potential and often progress to osteoarthritis, a costly disease affecting almost a third of adults in the United States. To treat these patients, cartilage repair therapies often use cell-seeded scaffolds, which are limited by donor site morbidity, high costs, and poor efficacy. To address these limitations, we developed an electrospun cell-free fibrous hyaluronic acid (HA) scaffold that delivers factors specifically designed to enhance cartilage repair: Stromal Cell-Derived Factor-1α (SDF-1α; SDF) to increase the recruitment and infiltration of mesenchymal stem cells (MSCs) and Transforming Growth Factor-β3 (TGF-β3; TGF) to enhance cartilage tissue formation. Scaffolds were characterized in vitro and then deployed in a large animal model of full-thickness cartilage defect repair. The bioactivity of both factors was verified in vitro, with both SDF and TGF increasing cell migration, and TGF increasing matrix formation by MSCs. In vivo, however, scaffolds releasing SDF resulted in an inferior cartilage healing response (lower mechanics, lower ICRS II histology score) compared to scaffolds releasing TGF alone. These results highlight the importance of translation into large animal models to appropriately screen scaffolds and therapies, and will guide investigators towards alternative growth factor combinations. STATEMENT OF SIGNIFICANCE: This study addresses an area of orthopaedic medicine in which treatment options are limited and new biomaterials stand to improve patient outcomes. Those suffering from articular cartilage injuries are often destined to have early onset osteoarthritis. We have created a cell-free nanofibrous hyaluronic acid (HA) scaffold that delivers factors specifically designed to enhance cartilage repair: Stromal Cell-Derived Factor-1α (SDF-1α; SDF) to increase the recruitment and infiltration of mesenchymal stem cells (MSCs) and Transforming Growth Factor-β3 (TGF-β3; TGF) to enhance cartilage tissue formation. To our knowledge, this study is the first to evaluate such a bioactive scaffold in a large animal model and demonstrates the capacity for dual growth factor release.

Accuracy of standard magnetic resonance imaging sequences for meniscal and chondral lesions versus knee arthroscopy. A prospective case-controlled study of 719 cases

BACKGROUND

Magnetic resonance imaging (MRI) is commonly used for diagnosis and as a research tool, but its accuracy is questionable. The goal of this study was to compare the accuracy of knee MRI with clinical assessment for diagnosing meniscal tears, and to determine the accuracy of MRI for grading chondral lesions, relative to arthroscopy.

METHODS

Physically active patients presenting with mechanical symptoms warranting a knee arthroscopy and satisfying the inclusion criteria, had both a knee arthroscopy and MRI performed. Arthroscopic findings were compared with those of MRI, using the International Chondral Research Society grading for chondral damage, and the presence or absence of a meniscal tear.

RESULTS

A total of 719 patients were recruited over a period of 6.5 years, average age 52 years (standard deviation, SD 5.2), male:female = 493:226. Kappa scores with standard errors (SE) for agreement between MRI and knee arthroscopy were 0.41 (SE 0.1) for medial meniscal tears, and 0.44 (SE 0.1) for lateral meniscal tears. For the grade of chondral damage, the Kappa scores with SE values were 0.09 (0.1), 0.17 (0.1), and 0.22 (0.07) for anterior, medial and lateral compartments, respectively. Using areas under the receiver operating characteristic curves, we found clinical assessment was more accurate than MRI for diagnosis of lateral meniscal tears (P < 0.001), and of similar accuracy for the diagnosis of medial meniscal tears (P = 0.12).

CONCLUSIONS

MRI has relatively poor correlation with arthroscopic findings for grading the chondral damage and was less accurate than clinical assessment for the diagnosis of lateral meniscal tears.

Classification, Categorization, and Algorithms for Articular Cartilage Defects

There is a critical unmet need in the clinical implementation of valid preventative and therapeutic strategies for patients with articular cartilage pathology based on the significant gap in understanding of the relationships between diagnostic data, disease progression, patient-related variables, and symptoms. In this article, the current state of classification and categorization for articular cartilage pathology is discussed with particular focus on machine learning methods and the authors propose a bedside-bench-bedside approach with highly quantitative techniques as a solution to these hurdles. Leveraging computational learning with available data toward articular cartilage pathology patient phenotyping holds promise for clinical research and will likely be an important tool to identify translational solutions into evidence-based clinical applications to benefit patients. Recommendations for successful implementation of these approaches include using standardized definitions of articular cartilage, to include characterization of depth, size, location, and number; using measurements that minimize subjectivity or validated patient-reported outcome measures; considering not just the articular cartilage pathology but the whole joint, and the patient perception and perspective. Application of this approach through a multistep process by a multidisciplinary team of clinicians and scientists holds promise for validating disease mechanism-based phenotypes toward clinically relevant understanding of articular cartilage pathology for evidence-based application to orthopaedic practice.

Naringin and bone marrow mesenchymal stem cells repair articular cartilage defects in rabbit knees through the transforming growth factor-β superfamily signaling pathway

The present study aimed to assess the effect of a combination of naringin and rabbit bone marrow mesenchymal stem cells (BMSCs) on the repair of cartilage defects in rabbit knee joints and to assess possible involvement of the transforming growth factor-β (TGF-β) signaling pathway in this process. After establishing an articular cartilage defect model in rabbit knees, 20 New Zealand rabbits were divided into a sham operation group (Sham), a model group (Mod), a naringin treatment group (Nar), a BMSC group (BMSCs) and a naringin + BMSC group (Nar/BMSCs). At 12 weeks after treatment, the cartilage was evaluated using the International Cartilage Repair Society (ICRS)'s macroscopic evaluation of cartilage repair scale, the ICRS's visual histological assessment scale, the Modified O'Driscoll grading system, histological staining (hematoxylin and eosin staining, toluidine blue staining and safranin O staining) and immunohistochemical staining (type-II collagen, TGF-β3 and SOX-9 immunostaining). Using the above grading systems to quantify the extent of repair, histological quantification and macro quantification of joint tissue repair showed that the Nar/BMSCs group displayed repair after treatment in comparison to the untreated Mod group. Among the injury model groups (Mod, Nar, BMSCs and Nar/BMSCs), the Nar/BMSCs group displayed the highest degree of morphological repair. The results of histological and immunohistochemical staining of the repaired region of the joint defect indicated that the BMSCs had a satisfactory effect on the repair of the joint structure but had a poor effect on the repair of cartilage quality. The Nar/BMSCs group displayed satisfactory therapeutic effects on both repair of the joint structure and cartilage quality. The expression level of type-II collagen was high in the Nar/BMSCs group. Additionally, staining of TGF-β3 and SOX-9 in the Nar/BMSCs group was the strongest compared with that of any other group in the present study. Naringin and/BMSCs together demonstrated a more efficient repair effect on articular cartilage defects in rabbit knees than the use of either treatment alone in terms of joint structure and cartilage quality. One potential mechanism of naringin action may be through activation and continuous regulation of the TGF-β superfamily signaling pathway, which can promote BMSCs to differentiate into chondrocytes.

Dual delivery of stem cells and insulin-like growth factor-1 in coacervate-embedded composite hydrogels for enhanced cartilage regeneration in osteochondral defects

Exogenous dual delivery of progenitor cell population and therapeutic growth factors (GFs) is one of alternative tissue engineering strategies for osteochondral tissue regeneration. In the present study, an implantable dual delivery platform was developed using coacervates (Coa) (i.e., a tertiary complex of poly(ethylene argininylaspartate diglyceride) (PEAD) polycation, heparin, and cargo insulin-like growth factor-1 (IGF-1), in thiolated gelatin (gelatin-SH)/ poly(ethylene glycol) diacrylate (PEGDA) interpenetrating network (IPN) hydrogels. Since Coa is able to protect cargo GF and maintain its long-term bioactivity, it is speculated that Coa-mediated delivery of chondrogenic factor IGF-1 with the aid of adipose-derived stem cells (ADSCs) would synergistically facilitate osteochondral tissue repair during physiological regeneration process. Our results indicate that gelatin-SH/PEGDA IPN hydrogels demonstrated biocompatibility and mechanical properties for a possible long-term transplantation, and PEAD-base Coa exhibited a sustained release of bioactive IGF-1 over 3 weeks. Subsequently, released IGF-1 from Coa could effectively induce chondrogenic differentiation of embedded ADSCs in the hydrogel, by showing enhanced glycosaminoglycan deposition and expression of chondrogenesis-associated genes. More importantly, at 12 weeks post-implantation in a rabbit full thickness osteochondral defect model, the quality of regenerative tissues in both chondral and subchondral layers was significantly improved in dual delivery of ADSC and IGF-1 in Coa encapsulated in gelatin-SH/PEGDA IPN hydrogels, as compared with a single delivery of ADSC only and a dual delivery without Coa. Therefore, we conclude that our Coa-embedded composite hydrogel platform could effectively augment osteochondral tissue regeneration holds promise for a feasible osteoarthritis therapeutic application.

Intra-Articular Injections of Mesenchymal Stem Cell Exosomes and Hyaluronic Acid Improve Structural and Mechanical Properties of Repaired Cartilage in a Rabbit Model

PURPOSE

To compare the efficacy of mesenchymal stem cell (MSC) exosomes with hyaluronic acid (HA) against HA alone for functional cartilage regeneration in a rabbit osteochondral defect model.

METHODS

Critical-size osteochondral defects (4.5-mm diameter and 1.5-mm depth) were created on the trochlear grooves in the knees of 18 rabbits and were randomly allocated to 2 treatment groups: (1) exosomes and HA combination and (2) HA alone. Three 1-mL injections of either exosomes and HA or HA alone were administered intra-articularly immediately after surgery and thereafter at 7 and 14 days after surgery. At 6 and 12 weeks, gross evaluation, histologic and immunohistochemical analysis, and scoring were performed. The functional biomechanical competence of the repaired cartilage also was evaluated.

RESULTS

Compared with defects treated with HA, defects treated with exosomes and HA showed significant improvements in macroscopic scores (P = .032; P = .001) and histologic scores (P = .005; P < .001) at 6 and 12 weeks, respectively. Defects treated with exosomes and HA also demonstrated improvements in mechanical properties compared with HA-treated defects, with significantly greater Young's moduli (P < .05) and stiffness (P < .05) at 6 and 12 weeks. By 12 weeks, the newly-repaired tissues in defects treated with exosomes and HA composed mainly of hyaline cartilage that are mechanically and structurally superior to that of HA-treated defects and demonstrated mechanical properties that approximated that of adjacent native cartilage (P > .05). In contrast, HA-treated defects showed some repair at 6 weeks, but this was not sustained, as evidenced by significant deterioration of histologic scores (P = .002) and a plateau in mechanical properties from 6 to 12 weeks.

CONCLUSIONS

This study shows that the combination of MSC exosomes and HA administered at a clinically acceptable frequency of 3 intra-articular injections can promote sustained and functional cartilage repair in a rabbit post-traumatic cartilage defect model, when compared with HA alone.

CLINICAL RELEVANCE

Human MSC exosomes and HA administered in combination promote functional cartilage repair and may represent a promising cell-free therapy for cartilage repair in patients.

Assessment of Cartilage Repair Quality With the International Cartilage Repair Society Score and the Oswestry Arthroscopy Score

The International Cartilage Repair Society (ICRS) score and the Oswestry Arthroscopic Score (OAS) have been validated to evaluate repair tissue quality. However, the performance of these scores has not been studied in typical patients undergoing cartilage repair and who have lesions of varying sizes. In this study, we compared the performance of the ICRS and the OAS scores and analyzed the effect of lesion characteristics on the performance of these two scores. Cartilage repair quality was assessed in a total of 104 arthroscopic observations of cartilage repair sites of the knee in 62 patients after autologous chondrocyte implantation. Two observers scored the repair areas independently with the ICRS and the OAS scores. The performance of both scores was evaluated according to internal consistency and inter-rater reliability and correlation between the scores. The frequency and proportion of disagreements were analyzed according to the repair site area and the given score. The correlation between the scores was good (r = 0.91, 95% confidence interval [CI]: 0.87-0.94). Both scores showed moderate internal consistency and inter-rater reliability. Cronbach's α was 0.88 (95% CI: 0.80-0.92) for the ICRS score and 0.79 (95% CI: 0.70-0.86) for the OAS score. The intraclass correlation coefficient was 0.89 (95% CI: 0.84-0.92) for the ICRS and 0.81 (95% CI: 0.74-0.87) for the OAS scores. The frequency and proportion of disagreements were higher in larger repair sites. In arthroscopic use, both ICRS and OAS scores perform similarly, however, their reliability deteriorates as the lesion size increases. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:555-562, 2020.

Osteochondral Allograft Transplantation of the Femoral Condyle Utilizing a Thin Plug Graft Technique

BACKGROUND

Previous studies showed clinical benefit and durable results of osteochondral allograft (OCA) transplantation for the treatment of femoral condyle lesions. However, the majority of these studies are difficult to interpret owing to the mixed results of different techniques and anatomic locations.

PURPOSE

To evaluate the outcome of OCA transplantation with thin plug grafts for treatment of isolated femoral condyle osteochondral lesions.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This study included 187 patients (200 knees) who underwent OCA transplantation for isolated osteochondral lesions on the femoral condyle between 1999 and 2014. For all cases, a thin plug technique was used with commercially available surgical instruments and the minimum amount of bone necessary for fixation. Evaluation included International Knee Documentation Committee score, Knee injury and Osteoarthritis Outcome Score, and patient satisfaction. Frequency and type of further surgery were assessed. Failure of the allograft was defined as further surgery involving removal of the allograft.

RESULTS

Mean follow-up was 6.7 years (range, 1.9-16.5 years). The mean age of patients at the time of surgery was 31 years, and 63% were male. The medial femoral condyle was affected in 69% of knees. A single thin plug graft was used in 145 knees (72.5%), and 2 grafts were used in 55 knees (27.5%). Mean allograft area was 6.3 cm², and graft thickness was 6.5 mm (cartilage and bone combined). Further surgery was required for 52 knees (26%), of which 16 (8% of entire cohort) were defined as allograft failures (4 OCA revisions, 1 arthrosurface, 6 unicompartmental knee arthroplasties, and 5 total knee arthroplasties). Median time to failure was 4.9 years. Survivorship of the allograft was 95.6% at 5 years and 91.2% at 10 years. Among patients with grafts remaining in situ at latest follow-up, clinically meaningful improvement in pain, function, and quality of life was reported. Satisfaction was reported by 89% of patients.

CONCLUSION

OCA transplantation with a thin plug graft technique is a valuable procedure for the treatment of femoral condyle osteochondral lesions, resulting in significant improvement in clinical scores, high patient satisfaction, and low reoperation and clinical failure rates.

Structure-function relationships of fetal ovine articular cartilage

It is crucial that the properties of engineered neocartilage match healthy native cartilage to promote the functional restoration of damaged cartilage. To accurately assess the quality of neocartilage and the degree of biomimicry achieved, its properties must be evaluated against native cartilage and tissue from which the cells for neocartilage formation were sourced. Fetal ovine cartilage is a promising and translationally relevant cell source with which to engineer neocartilage, yet, it is largely non-characterized. The influence of biomechanics during cartilage development, as well as their potential impact on structure-function relationships in utero motivates additional study of fetal cartilage. Toward providing tissue engineering design criteria and elucidating structure-function relationships, 11 locations across four regions of the fetal ovine stifle were characterized. Locational and regional differences were found to exist. Although differences in GAG content were observed, compressive stiffness did not vary or correlate with any biochemical component. Patellar cartilage tensile stiffness and strength were significantly greater than those of the medial condyle. Tensile modulus and UTS significantly correlated with pyridinoline content. More advanced zonal organization, more intense collagen II staining, and greater collagen and pyridinoline contents in the trochlear groove and patella suggest these regions exhibit a more advanced maturational state than others. Regional differences in functional properties and their correlations suggest that structure-function relationships emerge in utero. These data address the dearth of information of the fetal ovine stifle, may serve as a repository of information for cartilage engineering strategies, and may help elucidate functional adaptation in fetal articular cartilage. STATEMENT OF SIGNIFICANCE: Engineered neocartilage must be evaluated against healthy native cartilage and cell source tissue to determine its quality and degree of biomimicry. While fetal ovine cartilage has emerged as a promising and translationally relevant cell source with which to engineer neocartilage, it is largely non-characterized. Therefore, 11 locations across four regions (medial condyle, lateral condyle, trochlear groove, and patella) of the fetal ovine stifle were characterized. Importantly, locational and regional differences in functional properties were observed, and significant correlations of tensile properties to collagen and crosslink contents were detected, suggesting that functional adaptation begins in utero. This study provides a repository of quantitative information, clarifies the developmental order of cartilage functional properties, and informs future cartilage engineering efforts.

Comparison of Undifferentiated Versus Chondrogenic Predifferentiated Mesenchymal Stem Cells Derived From Human Umbilical Cord Blood for Cartilage Repair in a Rat Model

BACKGROUND

Human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) have gained much interest as a promising cell source for regenerative medicine owing to the noninvasive collection, availability, high expansion capacity, and low immunogenicity. However, few in vivo studies have reported the use of hUCB-MSCs on cartilage repair. Moreover, little study has been conducted on the effects of chondrogenic predifferentiation of hUCB-MSCs on cartilage repair.

PURPOSE

To compare the effectiveness of transplanting undifferentiated versus chondrogenic predifferentiated mesenchymal stem cells (MSCs) for treating osteochondral defects.

STUDY DESIGN

Controlled laboratory study.

METHODS

Critical-sized osteochondral defects were created in the trochlear grooves of rat femurs. In 20 rats, a composite of chondrogenic predifferentiated hUCB-MSCs (chondro-MSCs) and 4% hyaluronic acid (HA) hydrogel was transplanted into defects in the right knees, whereas undifferentiated hUCB-MSCs (undiff-MSCs) and 4% HA hydrogel were transplanted into the left knees. In the control groups, 4% HA hydrogel without MSCs was transplanted into defects in the right knees, and the defects in the left knees were left untreated in 20 rats. The cartilage repair was evaluated at 8 and 16 weeks after surgery.

RESULTS

Transplanting undiff-MSCs resulted in overall superior cartilage repair as compared with chondro-MSCs, HA alone, or no treatment. The articular surfaces of the defect sites in the undiff-MSC group were relatively smoother than those of the other treatments. The undiff-MSC group showed cellular morphology and arrangement similar to surrounding normal articular cartilage tissue at 16 weeks, both of which were also better than those of the other groups. In addition, the undiff-MSC group showed coloration similar to surrounding normal articular cartilage tissue at 16 weeks in safranin O and type II collagen immunohistochemical staining. The histological scores also revealed that cartilage repair with undiff-MSCs was better than that with chondro-MSCs, HA alone, or no treatment ( P < .05 in all).

CONCLUSION

This study demonstrated that treatment with undiff-MSCs resulted in more favorable cartilage repair than that with chondro-MSCs in a rat model. These findings indicate that chondrogenic predifferentiation of MSCs before transplantation does not enhance cartilage repair.

CLINICAL RELEVANCE

The results of this study support the use of undifferentiated MSCs, rather than chondrogenic predifferentiated MSCs, as a stem cell therapy strategy for cartilage repair.

Efficacy and safety of culture-expanded, mesenchymal stem/stromal cells for the treatment of knee osteoarthritis: a systematic review protocol

Background

Osteoarthritis is a progressive multifactorial condition of the musculoskeletal system with major symptoms including pain, loss of function, damage of articular cartilage and other tissues in the affected area. Knee osteoarthritis imposes major individual and social burden, especially with the cost and complexity of surgical interventions. Mesenchymal stem/stromal cells have been indicated as a treatment for degenerative musculoskeletal conditions given their capacity to differentiate into tissues of the musculoskeletal system.

Methods

A systematic search will be conducted in Medline, Embase, Cochrane Library, Scopus and relevant trial databases of English, Japanese, Korean, German, French, Italian, Spanish and Portuguese language papers published or in press to June 2018, with no restrictions on publication year applied. References will be screened and assessed for eligibility by two independent reviewers as per PRISMA guidelines. Cohort, cross-sectional or case controlled studies will be included for the analysis. Data extraction will be conducted using a predefined template and quality of evidence assessed. Statistical summaries and meta-analyses will be performed as necessary.

Discussion

Results will be published in relevant peer-reviewed scientific journals and presented at national or international conferences by the investigators.

Trial registration

The protocol was registered on the PROSPERO international prospective register of systematic reviews prior to commencement, CRD42018091763.

Electronic supplementary material

The online version of this article (10.1186/s13018-019-1070-8) contains supplementary material, which is available to authorized users.

Cartilage Health in Knees Treated with Metal Resurfacing Implants or Untreated Focal Cartilage Lesions: A Preclinical Study in Sheep

BACKGROUND

Full-depth cartilage lesions do not heal and the long-term clinical outcome is uncertain. In the symptomatic middle-aged (35-60 years) patient, treatment with metal implants has been proposed. However, the cartilage health surrounding these implants has not been thoroughly studied. Our objective was to evaluate the health of cartilage opposing and adjacent to metal resurfacing implants.

METHODS

The medial femoral condyle was operated in 9 sheep bilaterally. A metallic resurfacing metallic implant was immediately inserted into an artificially created 7.5 mm defect while on the contralateral knee the defect was left untreated. Euthanasia was performed at 6 months. Six animals, of similar age and study duration, from a previous study were used for comparison in the evaluation of cartilage health adjacent to the implant. Cartilage damage to joint surfaces within the knee, cartilage repair of the defect, and cartilage adjacent to the implant was evaluated macroscopically and microscopically.

RESULTS

Six animals available for evaluation of cartilage health within the knee showed a varying degree of cartilage damage with no statistical difference between defects treated with implants or left untreated ( P = 0.51; 95% CI -3.7 to 6.5). The cartilage adjacent to the implant (score 0-14; where 14 indicates no damage) remained healthy in these 6 animals showing promising results (averaged 10.5; range 9-11.5, SD 0.95). Cartilage defects did not heal in any case.

CONCLUSION

Treatment of a critical size focal lesion with a metal implant is a viable alternative treatment.

Functional tissue-engineered microtissue derived from cartilage extracellular matrix for articular cartilage regeneration

We developed a promising cell carrier prepared from articular cartilage slices, designated cartilage extracellular matrix (ECM)-derived particles (CEDPs), through processes involving physical pulverization, size screening, and chemical decellularization. Rabbit articular chondrocytes (ACs) or adipose-derived stem cells (ASCs) rapidly attached to the surface of the CEDPs and proliferated with high cell viability under microgravity (MG) condition in a rotary cell culture system (RCCS) or static condition. Gene profiling results demonstrated that ACs expanded on CEDPs exhibited significantly enhanced chondrogenic phenotypes compared with monolayer culture, and that ASCs differentiated into a chondrogenic phenotype without the use of exogenous growth factors. Moreover, MG culture conditions in a RCCS bioreactor were superior to static culture conditions in terms of maintaining the chondrogenic phenotype of ACs and inducing ACS chondrogenesis. With prolonged expansion, functional microtissue aggregates of AC- or ASC-laden CEDPs were formed. Further, AC- or ASC-based microtissues were directly implanted in vivo to repair articular osteochondral defects in a rabbit model. Histological results, biomechanical evaluations, and radiographic assessments indicated that AC- and ASC-based microtissues displayed equal levels of superior hyaline cartilage repair, whereas the other two treatment groups, in which osteochondral defects were treated with CEDPs alone or fibrin glue, exhibited primarily fibrous tissue repair. These findings provide an alternative method for cell culture and stem cell differentiation and a promising strategy for constructing tissue-engineered cartilage microtissues for cartilage regeneration.

STATEMENT OF SIGNIFICANCE

Despite the remarkable progress in cartilage tissue engineering, cartilage repair still remains elusive. In the present study, we developed a cell carrier, namely cartilage extracellular matrix-derived particles (CEDPs), for cell proliferation of articular chondrocytes (ACs) and adipose-derived stem cells (ASCs), which improved the maintenance of chondrogenic phenotype of ACs, and induced chondrogenesis of ASCs. Moreover, the functional microtissue aggregates of AC- or ASC-laden CEDPs induced equal levels of superior hyaline cartilage repair in a rabbit model. Therefore, our study demonstrated an alternative method for chondrocyte culture and stem cell differentiation, and a promising strategy for constructing tissue-engineered cartilage microtissues for in vivo articular cartilage repair and regeneration.

Can the Kerlan-Jobe Orthopaedic Clinic Shoulder and Elbow Score Be Reliably Administered Over the Phone?: A Randomized Study

Background:

The Kerlan-Jobe Orthopaedic Clinic (KJOC) shoulder and elbow outcome score is a functional assessment tool for the upper extremity of the overhead athlete, which is currently validated for administration in person.

Purpose/Hypothesis:

The purpose of this study was to validate the KJOC score for administration over the phone. The hypothesis was that no difference will exist in KJOC scores for the same patient between administration in person versus over the phone.

Study Design:

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

Methods:

Fifty patients were randomized to fill out the KJOC questionnaire either over the phone first (25 patients) or in person first (25 patients) based on an a priori power analysis. One week after the patients completed the initial KJOC on the phone or in person, they then filled out the score via the opposite method. Results were compared per question and for overall score.

Results:

There was a mean ± SD of 8 ± 5 days between when patients completed the first and second questionnaires. There were no significant differences in the overall KJOC score between the phone and paper groups (P = .139). The intraclass correlation coefficient comparing paper and phone scores was 0.802 (95% CI, 0.767-0.883; P < .001), with a Cronbach alpha of 0.89. On comparison of individual questions, there were significant differences for questions 1, 3, and 8 (P = .013, .023, and .042, respectively).

Conclusion:

The KJOC questionnaire can be administered over the phone with no significant difference in overall score as compared with that from in-person administration.

Effects of TGF-β Overexpression via rAAV Gene Transfer on the Early Repair Processes in an Osteochondral Defect Model in Minipigs

BACKGROUND

Application of the chondrogenic transforming growth factor beta (TGF-β) is an attractive approach to enhance the intrinsic biological activities in damaged articular cartilage, especially when using direct gene transfer strategies based on the clinically relevant recombinant adeno-associated viral (rAAV) vectors.

PURPOSE

To evaluate the ability of an rAAV-TGF-β construct to modulate the early repair processes in sites of focal cartilage injury in minipigs in vivo relative to control (reporter lacZ gene) vector treatment.

STUDY DESIGN

Controlled laboratory study.

METHODS

Direct administration of the candidate rAAV-human TGF-β (hTGF-β) vector was performed in osteochondral defects created in the knee joint of adult minipigs for macroscopic, histological, immunohistochemical, histomorphometric, and micro-computed tomography analyses after 4 weeks relative to control (rAAV- lacZ) gene transfer.

RESULTS

Successful overexpression of TGF-β via rAAV at this time point and in the conditions applied here triggered the cellular and metabolic activities within the lesions relative to lacZ gene transfer but, at the same time, led to a noticeable production of type I and X collagen without further buildup on the subchondral bone.

CONCLUSION

Gene therapy via direct, local rAAV-hTGF-β injection stimulates the early reparative activities in focal cartilage lesions in vivo.

CLINICAL RELEVANCE

Local delivery of therapeutic (TGF-β) rAAV vectors in focal defects may provide new, off-the-shelf treatments for cartilage repair in patients in the near future.

Platelet-Rich Plasma and Hyaluronic Acid Are Not Synergistic When Used as Biological Adjuncts with Autologous Osteochondral Transplantation

Introduction Autologous osteochondral transplantation (AOT) is a treatment for osteochondral lesions with known concerns, including histological degradation of the graft and poor cartilage integration. Platelet-rich plasma (PRP) and hyaluronic acid (HA) have been described has having the potential to improve results. The aim of this study was to evaluate the effect of PRP and HA on AOT in a rabbit model. Methods Thirty-six rabbits underwent bilateral knee AOT treated with either the biological adjunct (PRP, n = 12; HA, n = 12; PRP + HA, n = 12) or saline (control). PRP and HA were administered as an intra-articular injection. The rabbits were euthanized at 3, 6, or 12 weeks postoperatively. The graft sections were assessed using the modified International Cartilage Repair Society (ICRS) scoring system. The results from the PRP alone group is from previously published data. Results The mean modified ICRS histological score for the PRP-treated group was higher than its control ( P = 0.002). The mean modified ICRS histological score for the HA-treated group showed no difference compared with its control ( P = 0.142). The mean modified ICRS histological score for the PRP + HA-treated group was higher than its control ( P = 0.006). There was no difference between the mean modified ICRS scores of the PRP- and the PRP + HA-treated grafts ( P = 0.445). Conclusion PRP may decrease graft degradation and improve chondral integration in an animal model. In this model, the addition of HA was not synergistic for the parameters assessed.

LEVEL OF EVIDENCE

Basic science, Level V.

CLINICAL RELEVANCE

PRP can be used as an adjunct to AOT, which may decrease graft degeneration and improve clinical outcomes. HA may not influence AOT.

MR imaging of BioCartilage augmented microfracture surgery utilizing 2D MOCART and KOOS scores

OBJECTIVES

BioCartilage is a novel scaffold-based microfracture augmentation technique that has been shown to aid in chondrogenic differentiation of adult progenitor cells resulting in formation of more hyaline-like cartilage. As this cartilage repair technique becomes more commonplace, it is essential that the musculoskeletal radiologist and orthopedic surgeon gain familiarity with the surgical technique and its post-operative MR imaging findings.

METHODS

We present several case studies regarding MRI findings (modified clinical 2D MOCART) and clinical outcome (KOOS) scores in patients who have undergone this novel surgical procedure. For data analysis KOOS scores where dichotomized to scores greater or less than 80, and MOCART scores were dichotomized to scores greater or less than 50. A fisher exact test was then performed to determine if there was any correlation between parameters of the modified 2D MOCART and KOOS scores (Tables 2 and 3).

RESULTS

Marrow elements travel through the microfracture holes and interact with the scaffold created by BioCartilage, rather than creating their own fibrin scaffold, as is typically anticipated from a marrow stimulation procedure. Interestingly, the amount defect fill, presence of an intact surface, intact subchondral bone, or lack of effusion did not correlate with positive outcomes. Parameters that trended towards significance included presence of adhesions and subchondral lamina. Completeness of cartilage interface, homogeneity, and signal intensity also failed to reach statistical significance. In our experience, patients that demonstrated mild repair tissue surface irregularity, but with preservation of greater than 50% thickness compared to surrounding native cartilage, mild irregularity of subchondral plate, with vertical low signal intensity lines (sequela of prior microfracture surgery), and mild or no bone marrow edema pattern demonstrated higher KOOS scores.

CONCLUSION

Biocartilage in conjunction with microfracture is an encouraging cartilage restoration technique that promotes regeneration of more robust hyaline-like cartilage compared to the fibrocartilage formed after conventional microfracture. The T2 mapping properties of the repair tissue after successful BioCartilage augmented microfracture surgery are very similar to that of the adjacent native cartilage. Although there appear to be characteristic trends in a successful repair, further research is warranted to elucidate any correlations between specific characteristics of the repair and patient clinical outcomes.

Comparison of the Effects of Osteochondral Autograft Transplantation With Platelet-Rich Plasma or Platelet-Rich Fibrin on Osteochondral Defects in a Rabbit Model

BACKGROUND

Although osteochondral autograft transplantation (OAT) provides satisfactory outcomes for osteochondral defects, for large defects OAT is often inadequate because of graft availability. Osteochondral allograft transplantation is an alternative treatment for large defects, but this approach is limited by graft storage constraints and carries disease transmission risks. Platelet-rich fibrin (PRF) is a second-generation platelet concentrate, and its positive effect on articular cartilage has been reported. However, the effect of PRF with OAT of osteochondral defects is unknown.

PURPOSE

To compare the effects of OAT with platelet-rich plasma (PRP) and PRF on osteochondral defects in a rabbit model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Forty-two juvenile rabbits were divided into control, PRP, and PRF groups. In the control and PRP groups, a cylindrical osteochondral defect (5 mm in diameter and 2 mm in depth) was created on the patellar groove, and an osteochondral graft (3.5 mm in diameter and 5 mm in length) harvested from the contralateral side was inserted into the distal portion of the defect. After wound closure, either normal saline or PRP was injected in the knee. In the PRF group, a PRF clot was placed in the defect before grafting. The surgical site was macroscopically and histologically assessed after 3 and 12 weeks.

RESULTS

At 3 weeks, the PRF group (n = 8) was macroscopically healed compared with the other 2 groups (control, n = 7; PRP, n = 6) ( P < .005). Histologically, osteochondral graft cartilage of the PRF group had normal cellularity and higher amounts of safranin O staining relative to the other 2 groups ( P < .005). At 12 weeks, all 3 groups (n = 8 per group) were macroscopically healed with normal or nearly normal cartilage, and osteochondral graft cartilage was histologically hyaline cartilage. In contrast, the PRF group healed with hyaline-like cartilage at nongrafted defects, whereas the other 2 groups healed with fibrocartilage ( P < .001).

CONCLUSION

OAT with PRF maintained hyaline cartilage, and the nongrafted defect healed with hyaline-like cartilage.

CLINICAL RELEVANCE

PRF has the potential to improve clinical outcomes of OAT used to treat osteochondral lesions.

Development of a pilot cartilage surgery register

Background

Norway has no prospective surveillance system to monitor the outcome of knee cartilage surgery. In 2004 the Norwegian Registry of Knee Ligament (NKLR) was successfully established, and has yielded useful information on the treatment of patients with both knee ligament and combined knee injuries. Patients with focal cartilage defects (FCDs) in their knees have reduced function and the treatment is difficult. There are geographical variations in treatment, and the generalizability from randomized controlled studies is low. These patients would benefit from a standardized long-time follow-up through a cartilage surgery register.

The aim of the present study was to describe the development and report baseline challenges during the setting up of a pilot of a knee cartilage surgery register.

Methods

The study was designed as a prospective cohort study in the form of a register. Patients with full-thickness FCDs in the knee with International Cartilage Repair Society (ICRS) grade 3–4 on arthroscopy were included. The pilot included two hospitals; Oslo University Hospital (OUS), Ullevål and Akershus University Hospital (Ahus).

Results

We registered 58 patients with isolated FCDs, whereas 16 additional patients with full-thickness FCDs were registered through the NKLR. The patient cohort of patients with isolated FCDs consisted of 65% men and had a mean age of 29.8 years. The data are incomplete and the compliance varies from 18 to 73%. The distribution of mean KOOS scores were similar to previous patient cohorts with FCDs, with low scores for the KOOS Sport/Recreation and Quality of Life subscales.

Conclusion

The level of compliance demonstrated a large difference between the two participating hospitals. The compliance for the isolated FCDs were low in both locations, although it reached an acceptable level in one hospital when patients with combined injuries from the NKLR were included. The forms were incompletely filled out by the surgeons postoperatively and need to be revised prior the establishment of a nation-wide register.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-017-1638-6) contains supplementary material, which is available to authorized users.

Parylene scaffold for cartilage lesion

Evaluate parylene scaffold feasibility in cartilage lesion treatment, introducing a novel paradigm combining a reparative and superficial reconstructive procedure. Fifteen rabbits were used. All animals had both knees operated and the same osteochondral lesion model was created bilaterally. The parylene scaffold was implanted in the right knee, and the left knee of the same animal was used as control. The animals were euthanized at different time points after surgery: four animals at three weeks, three animals at six weeks, four animals at nine weeks, and four animals at 12 weeks. Specimens were analyzed by International Cartilage Repair Society (ICRS) macroscopic evaluation, modified Pineda histologic evaluation of cartilage repair, and collagen II immunostaining. Parylene knees were compared to its matched contra-lateral control knees of the same animal using the Wilcoxon matched-pairs signed rank. ICRS mean ± SD values for parylene versus control, three, six, nine and twelve weeks, respectively: 7.83 ± 1.85 versus 4.42 ± 1.08, p = 0.0005; 10.17 ± 1.17 versus 6.83 ± 1.17, p = 0.03; 10.89 ± 0.60 versus 7.33 ± 2.18, p = 0.007; 10.67 ± 0.78 versus 7.83 ± 3.40, p = 0.03. Modified Pineda mean ± SD values for parylene versus control, six, nine and twelve weeks, respectively: 3.37 ± 0.87 versus 6.94 ± 1.7, p < 0.0001; 5.73 ± 2.05 versus 6.41 ± 1.7, p = 0.007; 3.06 ± 1.61 versus 6.52 ± 1.51, p < 0.0001. No inflammation was seen. Parylene implanted knees demonstrated higher collagen II expression via immunostaining in comparison to the control knees. Parylene scaffolds are a feasible option for cartilage lesion treatment and the combination of a reparative to a superficial reconstructive procedure using parylene scaffolds led to better results than the reparative procedure alone.

Macroscopic cartilage repair scoring of defect fill, integration and total points correlate with corresponding items in histological scoring systems - a study in adult sheep

OBJECTIVE

To correlate osteochondral repair assessed by validated macroscopic scoring systems with established semiquantitative histological analyses in an ovine model and to test the hypothesis that important macroscopic individual categories correlate with their corresponding histological counterparts.

METHODS

In the weight-bearing portion of medial femoral condyles (n = 38) of 19 female adult Merino sheep (age 2-4 years; weight 70 ± 20 kg) full-thickness chondral defects were created (size 4 × 8 mm; International Cartilage Repair Society (ICRS) grade 3C) and treated with Pridie drilling. After sacrifice, 1520 blinded macroscopic observations from three observers at 2-3 time points including five different macroscopic scoring systems demonstrating all grades of cartilage repair where correlated with corresponding categories from 418 blinded histological sections.

RESULTS

Categories "defect fill" and "total points" of different macroscopic scoring systems correlated well with their histological counterparts from the Wakitani and Sellers scores (all P ≤ 0.001). "Integration" was assessed in both histological scoring systems and in the macroscopic ICRS, Oswestry and Jung scores. Here, a significant relationship always existed (0.020 ≤ P ≤ 0.049), except for Wakitani and Oswestry (P = 0.054). No relationship was observed for the "surface" between histology and macroscopy (all P > 0.05).

CONCLUSIONS

Major individual morphological categories "defect fill" and "integration", and "total points" of macroscopic scoring systems correlate with their corresponding categories in elementary and complex histological scoring systems. Thus, macroscopy allows to precisely predict key histological aspects of articular cartilage repair, underlining the specific value of macroscopic scoring for examining cartilage repair.