Arthroscopic autologous osteochondral grafting for cartilage defects of the knee: prospective study results at a minimum 7-year follow-up

Autologous Osteochondral Transfer of the Knee Demonstrates Continued High Rates of Return to Sport and Low Rates of Conversion to Arthroplasty at Long-Term Follow-Up: A Systematic Review

PURPOSE

To perform a systematic review of the literature to evaluate (1) activity level and knee function, (2) reoperation and failure rates, and (3) risk factors for reoperation and failure of autologous osteochondral transfer (AOT) at long-term follow-up.

METHODS

A comprehensive review of the long-term outcomes of AOT was performed. Studies reported on activity-based outcomes (Tegner Activity Scale) and clinical outcomes (Lysholm score and International Knee Documentation Committee score). Reoperation and failure rates as defined by the publishing authors were recorded for each study. Modified Coleman Methodology Scores were calculated to assess study methodological quality.

RESULTS

Twelve studies with a total of 495 patients and an average age of 32.5 years at the time of surgery and a mean follow-up of 15.1 years (range, 10.4-18.0 years) were included. The mean defect size was 3.2 cm2 (range, 1.9-6.9 cm2). The mean duration of symptoms before surgery was 5.1 years. Return to sport rates ranged from 86% to 100%. Conversion to arthroplasty rates ranged from 0% to 16%. The average preoperative International Knee Documentation Committee scores ranged from 32.9 to 36.8, and the average postoperative International Knee Documentation Committee scores at final follow-up ranged from 66.3 to 77.3. The average preoperative Lysholm scores ranged from 44.5 to 56.0 and the average postoperative Lysholm scores ranged from 70.0 to 96.5. The average preoperative Tegner scores ranged from 2.5 to 3.0, and the average postoperative scores ranged from 4.1 to 7.0.

CONCLUSIONS

AOT of the knee resulted in high rates of return to sport with correspondingly low rates of conversion to arthroplasty at long-term follow-up. In addition, AOT demonstrated significant improvements in long-term patient-reported outcomes from baseline.

LEVEL OF EVIDENCE

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

Mosaicplasty With High Tibial Osteotomy for Knee Subchondral Insufficiency Fracture Had Better Magnetic Resonance Observation of Cartilage Repair Tissue Scores With Less Bone Marrow Edema and Better Plug Union and Less Plug Necrosis Compared With Mosaicplasty Alone

PURPOSE

To determine the magnetic resonance imaging (MRI) findings after mosaicplasty (MOS) for knee subchondral insufficiency fracture (SIFK), and to analyze the relationship between MRI findings and clinical outcomes.

METHODS

We retrospectively reviewed the cases of consecutive patients who underwent MOS for SIFK with/without high tibial osteotomy (HTO) between January 1998 and December 2015. The MRI findings at 12 months after the surgery were assessed by the modified magnetic resonance observation of cartilage repair tissue (MOCART) score to determine the degree of bone marrow edema (BME), plug union, and plug necrosis. The clinical outcomes were assessed by Lysholm score to clarify the minimal clinically important difference (MCID) and patient acceptable symptom state analysis.

RESULTS

In total, 58 patients (17 men and 41 women) were enrolled in this study. Among them, 30 knees were treated by MOS alone and 28 knees were treated by MOS with HTO. The MOCART scores of patients who received MOS alone were significantly lower in BME score (P = .0060), plug union score (P = .0216), and in plug necrosis score (P = .0326) than patients who received MOS with HTO. BME lesion was less likely to persist among elderly (odds ratio 1.20, P = .0248) and female (OR 41.8, P = .0118) patients. The MCID of Lysholm score was 6.6 in MOS alone and 8.4 in MOS with HTO cases, but there were no significant association between MRI findings and the postoperative Lysholm score.

CONCLUSIONS

The MOS with HTO cases had better MOCART scores with less BME, better plug union, and less plug necrosis compared with MOS alone cases. Female and older patients had better resolution of BME, but there was no significant correlation between MRI findings and the postoperative Lysholm score. All cases in both groups showed improvement of Lysholm score exceeding MCID; thus, MOS may be effective as a joint preserving surgery for SIFK.

LEVEL OF EVIDENCE

Level IV, clinical case series.

Satisfactory clinical outcomes with autologous matrix-induced chondrogenesis in the treatment of grade IV chondral injuries of the knee

OBJECTIVE

The research aims to evaluate short- and medium-term outcomes of patients treated using autologous matrix-induced chondrogenesis (AMIC) with a hyaluronic acid scaffold (Hyalofast, Anika Therapeutics, MA, USA) in grade IV chondral lesions according to the Outerbridge classification in the knee.

METHODS

This is a multicentre, non-randomized, retrospective study conducted between 2017 and 2022. To determine the clinical outcome of the patients, the follow-up was done with the subjective International Knee Documentation Committee (IKDC) score, pre-surgery, and with a follow-up at 12, 24, and 32 months.

RESULTS

Fifty patients (28 female) with a mean age of 45.9 ± 12.7 years were recruited. The mean size of the lesion was 3.5 cm², and the injuries located in the patella (30%) and trochlear groove (24%) were the most frequent. The total IKDC clinical score significantly increased from baseline to the 32 months of follow-up with a mean difference of 36.4 (95% CI, 29.1-43.7, p < 0.001). Besides, there was a statistically significant improvement in all categories of the IKDC (symptoms, sports activities, function, and activity of daily living) compared between pre-surgery and 24 and 32 months of follow-up. The patients younger than 45 years presented better clinical outcomes than older ones with a difference between medians of 10.40 (95% CI, 1.10-11.50, p = 0.0247), and a negative correlation was found between the 32-month IKDC score and the age. In addition, no statistically significant difference was found when comparing the last results of the IKDC between patients with and without associated surgical procedures or between patients with single and several lesions, neither nor between men and women. The level of satisfaction with the procedure of all the patients, on a score of 1-10, was on average 8 ± 1.5.

CONCLUSION

Results of this study indicate that patients who underwent the AMIC procedure with hyaluronic acid scaffold for the treatment of grade IV chondral lesions in the knee presented satisfactory results throughout the follow-up.

LEVEL OF EVIDENCE

Level IV.

A bionic composite hydrogel with dual regulatory functions for the osteochondral repair

Due to the avascular nature of cartilage, it is difficult to heal and regenerate spontaneously after injury. At present, tissue engineering has become a promising strategy for repairing damaged cartilage, but the use of seed cells and growth factors is limited. In addition, the importance of mechanical compatibility of scaffold materials is often ignored. In this study, osteochondral scaffold was designed as a bilayer structure with a dense γ-Polyglutamic acid/carboxymethyl chitosan/bacterial cellulose (PGA/CMCS/BC) hydrogel cartilage layer and a porous nano HA-containing PGA/CMCS/BC hydrogel osteogenic layer. In addition, bioactive ions were introduced into the hydrogel scaffold to adjust the mechanical and swelling properties of the material to match the mechanical properties of natural articular cartilage. At the same time, based on the structural characteristics of bone and cartilage, magnesium and copper ions were introduced into the double-layer hydrogel scaffold, respectively, to prepare the cartilage layer and the bone layer, which endowed the material with excellent antibacterial properties and achieved the purpose of the integrated repair of bone and cartilage. The results showed that, after adding magnesium ions, the tensile breaking strength of material was increased from 0.66 MPa to 1.37 MPa，the corresponding compression modulus of the material (strain 0-12%) increased from 0.15 MPa to 0.58 MPa whilst the maximum mass swelling rate decreased from 155% to 75%. The results of in vivo experiments show that the group with bioactive ions had a much better effect on the repair of osteochondral defects, compared with group without bioactive ions, demonstrating such double ion regulation strategy is a very practical strategy for the treatment of osteochondral defects.

Return to Play Criteria Following Surgical Management of Osteochondral Defects of the Knee: A Systematic Review

OBJECTIVE

The objective of this study was to identify and describe the existing literature on criteria used for return to play (RTP) following surgical management of osteochondral defects of the knee.

DESIGN

A systematic review was performed to evaluate the surgical management of osteochondral defects of the knee in skeletally mature patients with a minimum of 2-year follow-up using Level I to IV studies in PubMed EMBASE from January 1998 to January 2016.

RESULTS

Twelve studies with at least one explicitly stated criterion for RTP were identified from a review of 253 published articles. The majority of included studies were Levels II and IV (33%, respectively). Autologous chondrocyte implantation (ACI) was exclusively evaluated in 33.3% of papers and 16.7% evaluated osteochondral allograft transplantation (OCA). Eight different RTP criteria were used alone or in combination across the reviewed studies and time was the most often utilized criterion (83.3%). Minimum time to RTP ranged from 3 to 18 months.

CONCLUSIONS

This systematic review identifies current criteria used in the available literature to dictate RTP. Time from surgery was the most commonly employed criterion across the reviewed studies. Given the complex biological processes inherent to the healing of cartilaginous defects, further research is needed to design more comprehensive guidelines for RTP that are patient-centered and utilize multiple functional and psychological domains relevant to the process of returning to sport.

Local depletion of proteoglycans mediates cartilage tissue repair in an ex vivo integration model

Successfully replacing damaged cartilage with tissue-engineered constructs requires integration with the host tissue and could benefit from leveraging the native tissue's intrinsic healing capacity; however, efforts are limited by a poor understanding of how cartilage repairs minor defects. Here, we investigated the conditions that foster natural cartilage tissue repair to identify strategies that might be exploited to enhance the integration of engineered/grafted cartilage with host tissue. We damaged porcine articular cartilage explants and using a combination of pulsed SILAC-based proteomics, ultrastructural imaging, and catabolic enzyme blocking strategies reveal that integration of damaged cartilage surfaces is not driven by neo-matrix synthesis, but rather local depletion of proteoglycans. ADAMTS4 expression and activity are upregulated in injured cartilage explants, but integration could be reduced by inhibiting metalloproteinase activity with TIMP3. These observations suggest that catabolic enzyme-mediated proteoglycan depletion likely allows existing collagen fibrils to undergo cross-linking, fibrillogenesis, or entanglement, driving integration. Catabolic enzymes are often considered pathophysiological markers of osteoarthritis. Our findings suggest that damage-induced upregulation of metalloproteinase activity may be a part of a healing response that tips towards tissue destruction under pathological conditions and in osteoarthritis, but could also be harnessed in tissue engineering strategies to mediate repair. STATEMENT OF SIGNIFICANCE: Cartilage tissue engineering strategies require graft integration with the surrounding tissue; however, how the native tissue repairs minor injuries is poorly understood. We applied pulsed SILAC-based proteomics, ultrastructural imaging, and catabolic enzyme blocking strategies to a porcine cartilage explant model and found that integration of damaged cartilage surfaces is driven by catabolic enzyme-mediated local depletion of proteoglycans. Although catabolic enzymes have been implicated in cartilage destruction in osteoarthritis, our findings suggest that damage-induced upregulation of metalloproteinase activity may be a part of a healing response that tips towards tissue destruction under pathological conditions. They also suggest that this natural cartilage tissue repair process could be harnessed in tissue engineering strategies to enhance the integration of engineered cartilage with host tissue.

Progress of Platelet Derivatives for Cartilage Tissue Engineering

Articular cartilage has limited self-regeneration ability for lacking of blood vessels, nerves, and lymph that makes it a great challenge to repair defects of the tissue and restore motor functions of the injured or aging population. Platelet derivatives, such as platelet-rich plasma, have been proved effective, safe, and economical in musculoskeletal diseases for their autologous origin and rich in growth factors. The combination of platelet derivatives with biomaterials provides both mechanical support and localized sustained release of bioactive molecules in cartilage tissue engineering and low-cost efficient approaches of potential treatment. In this review, we first provide an overview of platelet derivatives and their application in clinical and experimental therapies, and then we further discuss the techniques of the addition of platelet derivatives and their influences on scaffold properties. Advances in cartilage tissue engineering with platelet derivatives as signal factors and structural components are also introduced before prospects and concerns in this research field. In short, platelet derivatives have broad application prospects as an economical and effective enhancement for tissue engineering–based articular cartilage repair.

Autologous osteochondral transplantation for focal femoral condyle defects: Comparison of mosaicplasty by arthrotomy vs. arthroscopy

BACKGROUND

While many studies have reported the outcomes of open mosaicplasty, data on arthroscopic mosaicplasty are scarce. Only two cadaver studies have compared arthrotomy and arthroscopy. Moreover, the patello-femoral joint, which is the main donor site, has never been assessed using a specific functional score. The objective of this in vivo study was to compare arthrotomy and arthroscopy for mosaicplasty using both a global functional knee score and a specific score of the patello-femoral joint.

HYPOTHESIS

The arthroscopic technique results in better functional patello-femoral outcomes.

MATERIAL AND METHODS

We retrospectively compared two groups of 17 patients who underwent mosaicplasty for focal condylar cartilage defects, at our department between 2009 and 2019. Functional outcomes were assessed using the Kujala score and the Lysholm score, at least 1 year after surgery. The return to sports was assessed using the Tegner score.

RESULTS

Mean follow-up was 67.4±15.9 months in the arthrotomy group and 45.2±35.1 months in the arthroscopy group (p<0.01). Cartilage defect size was similar in the two groups (arthrotomy: 1.21±0.91cm²; arthroscopy: 0.92±1.23cm²; p=0.052). The mean Kujala score was 85±21.3 in the arthrotomy group and 91.9±13.7 in the arthroscopy group (p=0.064). The mean Lysholm score was 83.9±19.8 with arthrotomy and 89.5±14.9 with arthroscopy (p=0.1). The Kujala score was greater than 95 in 4 (26%) arthrotomy patients and 13 (81%) arthroscopy patients (p=0.003). The Lysholm score was higher than 95 in 4 (26%) arthrotomy patients and 12 (75%) arthroscopy patients (p=0.012). No patient underwent surgical revision for autograft failure.

DISCUSSION

This is the first clinical study comparing arthrotomy and arthroscopy for mosaicplasty. Clinical outcomes were good with both techniques. The proportion of patients with excellent Lysholm and Kujala functional scores was significantly higher in the arthroscopy group than in the arthrotomy group. This result may be ascribable to decreased donor-site morbidity obtained with arthroscopy.

LEVEL OF EVIDENCE

IV, retrospective observational comparative study.

Repair of osteochondral defects mediated by double-layer scaffolds with natural osteochondral-biomimetic microenvironment and interface

Tissue engineering provides a new approach for the treatment of osteochondral defects. However, the lack of an ideal double-layer scaffold with osteochondral-biomimetic microenvironment and interface similar to native articular tissue greatly limits clinical translation. Our current study developed a double-layer acellular osteochondral matrix (AOM) scaffold with natural osteochondral-biomimetic microenvironment and interface by integrating ultraviolet (UV) laser and decellularization techniques. The laser parameters were optimized to achieve a proper pore depth close to the osteochondral interface, which guaranteed complete decellularization, sufficient space for cell loading, and relative independence of the chondrogenic and osteogenic microenvironments. Gelatin-methacryloyl (GelMA) hydrogel was further used as the cell carrier to significantly enhance the efficiency and homogeneity of cell loading in the AOM scaffold with large pore structure. Additionally, in vitro results demonstrated that the components of the AOM scaffold could efficiently regulate the chondrogenic/osteogenic differentiations of bone marrow stromal cells (BMSCs) by activating the chondrogenic/osteogenic related pathways. Importantly, the AOM scaffolds combined with BMSC-laden GelMA hydrogel successfully realized tissue-specific repair of the osteochondral defects in a knee joint model of rabbit. The current study developed a novel double-layer osteochondral biomimetic scaffold and feasible strategy, providing strong support for the tissue-specific repair of osteochondral defects and its future clinical translation.

Hydrogel-hydroxyapatite-monomeric collagen type-I scaffold with low-frequency electromagnetic field treatment enhances osteochondral repair in rabbits

BACKGROUND

Cartilage damage is a common medical issue in clinical practice. Complete cartilage repair remains a significant challenge owing to the inferior quality of regenerative tissue. Safe and non-invasive magnetic therapy combined with tissue engineering to repair cartilage may be a promising breakthrough.

METHODS

In this study, a composite scaffold made of Hydroxyapatite-Collagen type-I (HAC) and PLGA-PEG-PLGA thermogel was produced to match the cartilage and subchondral layers in osteochondral defects, respectively. Bone marrow mesenchymal stem cells (BMSC) encapsulated in the thermogel were stimulated by an electromagnetic field (EMF). Effect of EMF on the proliferation and chondrogenic differentiation potential was evaluated in vitro. 4 mm femoral condyle defect was constructed in rabbits. The scaffolds loaded with BMSCs were implanted into the defects with or without EMF treatment. Effects of the combination treatment of the EMF and composite scaffold on rabbit osteochondral defect was detected in vivo.

RESULTS

In vitro experiments showed that EMF could promote proliferation and chondrogenic differentiation of BMSCs partly by activating the PI3K/AKT/mTOR and Wnt1/LRP6/β-catenin signaling pathway. In vivo results further confirmed that the scaffold with EMF enhances the repair of osteochondral defects in rabbits, and, in particular, cartilage repair.

CONCLUSION

Hydrogel-Hydroxyapatite-Monomeric Collagen type-I scaffold with low-frequency EMF treatment has the potential to enhance osteochondral repair.

3D MRI of Articular Cartilage

Osteoarthritis, characterized by the breakdown of articular cartilage and other joint structures, is one of the most prevalent and disabling chronic diseases in the United States. Magnetic resonance imaging is a commonly used imaging modality to evaluate patients with joint pain. Both two-dimensional fast spin-echo sequences (2D-FSE) and three-dimensional (3D) sequences are used in clinical practice to evaluate articular cartilage. The 3D sequences have many advantages compared with 2D-FSE sequences, such as their high in-plane spatial resolution, thin continuous slices that reduce the effects of partial volume averaging, and ability to create multiplanar reformat images following a single acquisition. This article reviews the different 3D imaging techniques available for evaluating cartilage morphology, illustrates the strengths and weaknesses of 3D approaches compared with 2D-FSE approaches for cartilage imaging, and summarizes the diagnostic performance of 2D-FSE and 3D sequences for detecting cartilage lesions within the knee and hip joints.

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.

Prone-positioned knee arthroscopy for isolated retropatellar cartilage defects with gel-type autologous chondrocyte implantation

OBJECTIVE

Treatment of isolated retropatellar cartilage defects using current gel-type regenerative methods requires settlement of the gel to the underlying subchondral bone under gravity; thus, prone positioned arthroscopy is used.

INDICATIONS

Isolated retropatellar contained cartilage defect size >2.5 cm². Age <40 years, epiphyseal closure, cartilage defect grade 3/4 (International Cartilage Repair Society).

CONTRAINDICATIONS

Cartilage defects at medial or lateral femorotibial compartments, at the trochlea, with degenerative genesis, rheumatoid arthritis, local infection, patellar malalignment, patellofemoral dysplasia, knee instability, knee malalignment >3°, kissing lesions.

SURGICAL TECHNIQUE

Two-stage procedure: At initial arthroscopy, chondrocytes were harvested. At the second stage, the patient was positioned prone and the leg with a thigh tourniquet was fixed in a leg holder. Removal of table extension below the knee and support of foot in sling to prevent knee hyperextension. Placement of 2 lateral portals. Lesion visualized and debrided, followed by aspiration of intra-articular fluid. A loop, placed posterior to the patellar ligament using a lasso, was used to suspend a weight to expand the patellofemoral space. The lesion was then dried using a sponge. NOVOCART® Inject (TETEC, Reutlingen, Germany) administered onto the defect. Gel was allowed to solidify for 15 min and operation was completed.

POSTOPERATIVE MANAGEMENT

Knee locked in extension using a brace for 6 weeks. Continuous passive motion applied and incrementally increased until full range of motion (ROM) at week 6. Weight-bearing as tolerated was allowed with the knee in extension. Routine clinical follow-up after 3, 6 and 12 months.

RESULTS

Mean age of the 5 patients was 23 ± 6 (range 14-30) years; mean follow-up time after surgery 28 ± 7 (range 20-40) months. All patients returned to full activity without residual knee ROM restriction. Clinical examination at the latest follow-up revealed a Kujala score of 90 ± 12 points and Lysholm score of 95 ± 5 points. MRI showed filled cartilage defects in all patients. Mocart score was 63 ± 7 points. Cartilage was inhomogeneous and hyperintense at the repaired site. Quantitative measurement of the patella mobility of the operated knee under a translating force of 10 N showed medial and lateral displacements of 21 ± 5 and 15 ± 2 mm and on the healthy side 22 ± 5 and 19 ± 3 mm, respectively.

Matrix-assisted chondrocyte transplantation with bone grafting for knee osteochondritis dissecans: stable results at 12 years

PURPOSE

To document clinical and radiological results of arthroscopic matrix-assisted autologous chondrocyte transplantation (MACT) combined with bone grafting for the treatment of knee osteochondritis dissecans (OCD) at long-term follow-up.

METHODS

Thirty-one knees in 29 patients (20.4 ± 5.7 years) were treated for symptomatic unfixable OCD lesions (2.6 ± 1.1 cm²) and prospectively evaluated at 2, 5, and 12 years (average, minimum 10 years). Patients were evaluated over time with IKDC subjective score, EQ-VAS, and Tegner scores. Failures were also documented. At the final follow-up, MRI evaluation was performed in 14 knees with the MOCART 2.0 score.

RESULTS

Beside 4 early failures, an overall clinical improvement was documented: the IKDC subjective score improved from 39.9 ± 16.8 to 82.1 ± 17.0 and 84.8 ± 17.2 at 2 and 5 years, respectively (p < 0.0005), and remained stable for up to 12 years (85.0 ± 20.2). EQ-VAS and Tegner scores presented similar trends, but patients did not reach their original activity level. Worse results were obtained for lesions bigger than 4 cm². At MRI evaluation, subchondral bone abnormalities were detected in over 85% of knees at long-term follow-up.

CONCLUSIONS

Arthroscopic bone grafting followed by MACT for unfixable knee OCD can offer a promising and stable clinical outcome over time in lesions smaller than 4 cm², with a low failure rate of 13%. Persistent subchondral alterations were documented at long-term MRI evaluation, suggesting the limits of this approach to regenerate the osteochondral unit in patients affected by knee OCD.

LEVEL OF EVIDENCE

IV.

Managing Chondral Lesions: A Literature Review and Evidence-Based Clinical Guidelines

BACKGROUND

Articular cartilage lesions are becoming increasingly common. Optimum diagnosis and management of chondral defects cause a lot of dilemma. A number of surgical methods have been reported in the literature for treating focal cartilage defects. There is a lack of consensus on the most effective management strategy, with newer surgical and cell-based treatments being advocated regularly.

STUDY DESIGN AND METHODS

A clinical review is constructed by appraising the published literature about clinical evaluation and diagnostic modalities for articular cartilage defects and subsequent surgical procedures, management strategies employed for such lesions. Prominent available databases (PUBMED, EMBASE, Cochrane) were also searched for trials comparing functional outcomes following cartilage procedures. Synthesis of a practical management guideline is then attempted based on the evidence assessed.

RESULTS

Systematic examination and optimal use of diagnostic imaging are an important facet of cartilage defect management. Patient and lesion factors greatly influence the outcome of cartilage procedures and must be considered while planning management. Smaller lesions < 2 cm² respond well to all treatment modalities. Autologous osteochondral transplants (OATs) are effective in high activity individuals with intermediate lesions. For larger lesions > 4 cm², newer generation autologous chondrocyte implantation (ACI) has shown promising and durable results. Stem cells with scaffolds may provide an alternate option. Orthobiologics are a useful adjunct to the surgical procedures, but need further evaluation.

CONCLUSIONS

Most treatment modalities have their role in appropriate cases and management needs to be individualized for patients. The search for the perfect cartilage restoration procedure continues.

Sporting participation following the operative management of chondral defects of the knee at mid-term follow up: a systematic review and meta-analysis

PURPOSE

The purpose of this study was to perform a systematic review of the reparticipation in sport at mid-term follow up in athletes who underwent biologic treatment of chondral defects in the knee and compare the rates amongst different biologic procedures.

METHODS

A search of PubMed/Medline and Embase was performed in May 2020 in keeping with Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. The criteria for inclusion were observational, published research articles studying the outcomes and rates of participation in sport following biologic treatments of the knee with a minimum mean/median follow up of 5 years. Interventions included microfracture, osteochondral autograft transfer (OAT), autologous chondrocyte implantation (ACI), matrix-induced autologous chondrocyte implantation (MACI), osteochondral allograft, or platelet rich plasma (PRP) and peripheral blood stem cells (PBSC). A random effects model of head-to-head evidence was used to determine rates of sporting participation following each intervention.

RESULTS

There were twenty-nine studies which met the inclusion criteria with a total of 1276 patients (67% male, 33% female). The mean age was 32.8 years (13-69, SD 5.7) and the mean follow up was 89 months (SD 42.4). The number of studies reporting OAT was 8 (27.6%), ACI was 6 (20.7%), MACI was 7 (24.1%), microfracture was 5 (17.2%), osteochondral allograft was 4 (13.8%), and one study (3.4%) reported on PRP and PBSC. The overall return to any level of sport was 80%, with 58.6% returning to preinjury levels. PRP and PBSC (100%) and OAT (84.4%) had the highest rates of sporting participation, followed by allograft (83.9%) and ACI (80.7%). The lowest rates of participation were seen following MACI (74%) and microfracture (64.2%).

CONCLUSIONS

High rates of re-participation in sport are sustained for at least 5 years following biologic intervention for chondral injuries in the knee. Where possible, OAT should be considered as the treatment of choice when prolonged participation in sport is a priority for patients. However, MACI may achieve the highest probability of returning to the same pre-injury sporting level.

LEVEL OF EVIDENCE

IV.

Current hip cartilage regeneration/repair modalities: a scoping review of biologics and surgery

PURPOSE

The rapidly growing and emerging nature of biologics have made indications for regenerative and reparative hip therapies ever changing, with at times only early-stage evidence for their use. The purpose of this study was to review and summarize the currently available data on the management of hip cartilage injuries and osteoarthritis.

METHODS

A scoping review of the available scientific literature for hip biologics was performed, with available evidence for hyaluronic acid (HA), platelet rich plasma (PRP), stem/stromal cells, microfracture, mosaicplasty, osteochondral allograft, and cell-based therapies investigated.

RESULTS

To date, there exist better guidelines and further consensus concerning knee joint biologic treatments than the hip due to a greater number of studies as well as the more recent emergence of hip preservation approaches. However, increasing evidence is available for the selective implementation of biologics on an individualized basis with attention to lesion size and location.

CONCLUSION

Orthopedic surgeons are at an exciting crossroads in medicine, where hip biologic therapies are evolving and increasingly available. Timetested interventions such as arthroplasty have shown good results and still have a major role to play but newer, regenerative approaches have the potential to effectively delay or reduce the requirement for such invasive procedures.

High-Grade Patellar Chondral Defects: Promising Results From Management With Osteochondral Autografts

Background:

Patellar chondral defects represent up to 34.6% of defects found during routine arthroscopy. Surgical management has evolved during the past 20 years in an effort to develop techniques to replace hyaline cartilage. Currently, the only technique that achieves this is osteochondral autologous transfer (OAT). Although good and excellent results have often been reported at midterm and long-term follow-up for femoral lesions, little is known about isolated patellar defects.

Purpose:

To assess clinical and imaging results of patients treated with OAT for high-grade patellar defects.

Study Design:

Case series; Level of evidence, 4.

Methods:

This was a retrospective study on all patients who received OAT for high-grade symptomatic patellar chondral defects between 2010 and 2018 at our institution. The study included patients younger than 40 years of age with anterior knee pain and a grade 4 International Cartilage Repair Society patellar chondral defect between 1 and 2.5 cm². Patients with surgery in other knee compartments, concomitant anterior cruciate ligament ruptures, infection, rheumatoid arthritis, and degenerative lesions were excluded. Six months postoperatively, all patients underwent magnetic resonance imaging (MRI) to allow assessment of graft integrity via the MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score to evaluate morphologic features and integration. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Kujala scores were used to assess functional outcomes at final follow-up.

Results:

A total of 26 patients who received a patellar OAT were included. Most patients were male (88.4%), and the mean ± SD age was 28.5 ± 9.7 years. Patellar chondral defects had a median size of 180 mm² (range, 64-250 mm²), and patients received a median of 1 autograft (range, 1-3). Functional outcomes assessed at a minimum of 1 year after surgery showed a mean Kujala score of 90.42 ± 6.7 and a mean WOMAC score of 95 ± 3.6. MRI revealed a median MOCART score of 75 points (range, 20-90 points).

Conclusion:

To our knowledge, this is the largest series to date regarding isolated patellar OAT. At midterm follow-up, most patients reported good and excellent results regarding symptoms and activity levels. Most autografts showed good osseous integration and excellent filling of the chondral surface, as evidenced on MRI. OAT is a good alternative to treat high-grade patellar chondral defects, especially among young patients.

Promising outcomes of hip mosaicplasty by minimally invasive anterior approach using osteochondral autografts from the ipsilateral femoral head

PURPOSE

Recent studies demonstrated promising results of mosaicplasty for femoral head osteochondral lesions using posterior and lateral approaches. This study aimed to evaluate outcomes of mosaicplasty using ipsilateral femoral head autografts by minimally invasive anterior approach. The hypothesis was that this surgical technique would grant satisfactory clinical outcomes with considerable improvement of clinical scores.

METHODS

A consecutive series of 27 mosaicplasties, to treat osteochondral lesions of the femoral head measuring 1.6 ± 0.7 cm² (range 0.8-4.0) in patients aged 28.7 ± 7.4 years (range 19-44), was evaluated using the mHHS and WOMAC scores at minimum follow-up of 12 months. All patients were operated by minimally invasive anterior (Hueter) approach and osteochondral plugs were harvested from the non-weight-bearing portion of the femoral head. Adjuvant osteoplasty was necessary for some patients at the acetabulum (n = 3), femur (n = 14) or both (n = 2).

RESULTS

Three patients were excluded due to concomitant periacetabular osteotomies or shelf procedures, one patient could not be reached, and another was revised to THA. This left 22 patients for clinical assessment at 39.4 ± 23.2 months (12.0-90.2). Their mHHS improved from 56.3 ± 12.6 to 88.4 ± 9.9, and WOMAC improved from 45.1 ± 16.9 to 80.6 ± 13.0. Two patients (8.4%) underwent arthroscopy at 13 and 30 months to remove painful residual cam-type deformities. Regression analyses revealed that net improvement in WOMAC decreased with lesion size (p = 0.002) and increased with follow-up (p = 0.004).

CONCLUSIONS

Hip mosaicplasty using autografts from the ipsilateral femoral head, performed by minimally invasive anterior approach, granted satisfactory outcomes and functional improvements. Caution is, however, advised for lesions > 2 cm² (diameter > 16 mm) which may be a threshold limit for this procedure.

LEVEL OF EVIDENCE

Level IV, Case series.

Cost-efficacy of Knee Cartilage Defect Treatments in the United States

BACKGROUND

Multiple knee cartilage defect treatments are available in the United States, although the cost-efficacy of these therapies in various clinical scenarios is not well understood.

PURPOSE/HYPOTHESIS

The purpose was to determine cost-efficacy of cartilage therapies in the United States with available mid- or long-term outcomes data. The authors hypothesized that cartilage treatment strategies currently approved for commercial use in the United States will be cost-effective, as defined by a cost <$50,000 per quality-adjusted life-year over 10 years.

STUDY DESIGN

Systematic review.

METHODS

A systematic search was performed for prospective cartilage treatment outcome studies of therapies commercially available in the United States with minimum 5-year follow-up and report of pre- and posttreatment International Knee Documentation Committee subjective scores. Cost-efficacy over 10 years was determined with Markov modeling and consideration of early reoperation or revision surgery for treatment failure.

RESULTS

Twenty-two studies were included, with available outcomes data on microfracture, osteochondral autograft, osteochondral allograft (OCA), autologous chondrocyte implantation (ACI), and matrix-induced ACI. Mean improvement in International Knee Documentation Committee subjective scores at final follow-up ranged from 17.7 for microfracture of defects >3 cm² to 36.0 for OCA of bipolar lesions. Failure rates ranged from <5% for osteochondral autograft for defects requiring 1 or 2 plugs to 46% for OCA of bipolar defects. All treatments were cost-effective over 10 years in the baseline model if costs were increased 50% or if failure rates were increased an additional 15%. However, if efficacy was decreased by a minimum clinically important amount, then ACI (periosteal cover) of femoral condylar lesions ($51,379 per quality-adjusted life-year), OCA of bipolar lesions ($66,255) or the patella ($66,975), and microfracture of defects >3 cm² ($127,782) became cost-ineffective over 10 years.

CONCLUSION

Currently employed treatments for knee cartilage defects in the United States are cost-effective in most clinically acceptable applications. Microfracture is not a cost-effective initial treatment of defects >3 cm². OCA transplantation of the patella or bipolar lesions is potentially cost-ineffective and should be used judiciously.

Comparative Effectiveness of Cartilage Repair With Respect to the Minimal Clinically Important Difference

BACKGROUND

Recent studies demonstrated a 5% increase in cartilage repair procedures annually in the United States. There is currently no consensus regarding a superior technique, nor has there been a comprehensive evaluation of postoperative clinical outcomes with respect to a minimal clinically important difference (MCID).

PURPOSE

To determine the proportion of available cartilage repair studies that meet or exceed MCID values for clinical outcomes improvement over short-, mid-, and long-term follow-up.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A systematic review was performed via the Medline, Scopus, and Cochrane Library databases. Available studies were included that investigated clinical outcomes for microfracture (MFX), osteoarticular transfer system (OATS), osteochondral allograft transplantation, and autologous chondrocyte implantation/matrix-induced autologous chondrocyte implantation (ACI/MACI) for the treatment of symptomatic knee chondral defects. Cohorts were combined on the basis of surgical intervention by performing a meta-analysis that utilized inverse-variance weighting in a DerSimonian-Laird random effects model. Weighted mean improvements in International Knee Documentation Committee (IKDC), Lysholm, and visual analog scale for pain (VAS pain) scores were calculated from preoperative to short- (1-4 years), mid- (5-9 years), and long-term (≥10 years) postoperative follow-up. Mean values were compared with established MCID values per 2-tailed 1-sample Student t tests.

RESULTS

A total of 89 studies with 3894 unique patients were analyzed after full-text review. MFX met MCID values for all outcome scores at short- and midterm follow-up with the exception of VAS pain in the midterm. OATS met MCID values for all outcome scores at all available time points; however, long-term data were not available for VAS pain. Osteochondral allograft transplantation met MCID values for IKDC at short- and midterm follow-up and for Lysholm at short-term follow-up, although data were not available for other time points or for VAS pain. ACI/MACI met MCID values for all outcome scores (IKDC, Lysholm, and VAS pain) at all time points.

CONCLUSION

In the age of informed consent, it is important to critically evaluate the clinical outcomes and durability of cartilage surgery with respect to well-established standards of clinical improvement. MFX failed to maintain VAS pain improvements above MCID thresholds with follow-up from 5 to 9 years. All cartilage repair procedures met MCID values at short- and midterm follow-up for IKDC and Lysholm scores; ACI/MACI and OATS additionally met MCID values in the long term, demonstrating extended maintenance of clinical benefits for patients undergoing these surgical interventions as compared with MFX.

Fluid imbibition at the bone-cartilage interface is associated with need for early chondroplasty following osteochondral allografting of the knee

PURPOSE

To determine the clinical significance of fluid imbibition at the bone-cartilage interface seen on postoperative MRI scans after osteochondral grafting of chondral lesions of the knee.

METHODS

Retrospective review of patients enrolled in a prospective cartilage repair registry. Included patients underwent osteochondral autografting or allografting of the knee, had minimum one year of clinical follow-up, and underwent at least two postoperative MRI scans. The primary outcome was reoperation for arthroscopic debridement and chondroplasty or graft revision. Secondary outcomes included the radiographic fate of fluid imbibition.

RESULTS

A total of 48 knees in 46 patients were analyzed, with mean 39 months clinical follow-up. Nine patients (19%) had fluid imbibition on at least one postoperative MRI scan, all of whom received allograft. Of these, two (22%) required eventual graft revision, four (45%) underwent arthroscopic chondroplasty but did not require revision, and three (33%) did not require any additional surgery by final follow-up. No demographic or surgical variable was associated with the presence of fluid imbibition. Fluid imbibition was significantly associated with need for chondroplasty (p = 0.05), but not graft revision.

CONCLUSIONS

Fluid imbibition on postoperative MRI following osteochondral allografting of the knee is associated with the need for arthroscopic chondroplasty, but should not be interpreted as a sign of a failing graft.

LEVEL OF EVIDENCE

Level IV, Case Series.

Recombinant human FGF18 preserves depth-dependent mechanical inhomogeneity in articular cartilage

Articular cartilage is a specialised tissue that has a relatively homogenous endogenous cell population but a diverse extracellular matrix (ECM), with depth-dependent mechanical properties. Repair of this tissue remains an elusive clinical goal, with biological interventions preferred to arthroplasty in younger patients. Osteochondral transplantation (OCT) has emerged for the treatment of cartilage defects and osteoarthritis. Fresh allografts stored at 4 °C have been utilised, though matrix and cell viability loss remains an issue. To address this, several studies have developed media formulations to maintain cartilage explants in vitro. One promising factor for these applications is sprifermin, a human-recombinant fibroblast growth factor-18, which stimulates chondrocyte proliferation and matrix synthesis and is in clinical trials for the treatment of osteoarthritis. The study hypothesis was that addition of sprifermin during storage would maintain the unique depth-dependent mechanical profile of articular cartilage explants, a feature not often evaluated. Explants were maintained for up to 6 weeks with or without a weekly 24 h exposure to sprifermin (100 ng/mL) and the compressive modulus was assessed. Results showed that sprifermin-treated samples maintained their depth-dependent mechanical profile through 3 weeks, whereas untreated samples lost their mechanical integrity over 1 week of culture. Sprifermin also affected ECM balance by maintaining the levels of extracellular collagen and suppressing matrix metalloproteinase production. These findings support the use of sprifermin as a medium additive for OCT allografts during in vitro storage and present a potential mechanism where sprifermin may impact a functional characteristic of articular cartilage in repair strategies.

[Mid-term results in the treatment of osteochondritis dissecans of the femoral condyles using osteochondral grafting (mosaic arthroplasty)]

Several surgical procedures, including mosaic arthroplasty, can be used to treat patients with cartilage loss in the femoral condyles. This study aims to assess mid-term clinical and radiological results as well as the main prognostics elements. We conducted a retrospective epidemiological study over a period of 15 years. During the study period we collected data from 35 workable medical records of patients with osteochondritis dissecans of the femoral condyles treated by mosaic arthroplasty, with an average follow-up of 24 months. The level of complaints as well as preoperative knee function were evaluated and compared with the healthy knee according to the International Cartilage Repair Society (ICRS) score, the International Knee Documentation Committee (IKDC) score and visual analogue scale (VAS). It was less than 60% in 27 patients. During the follow-up period, the results were analyzed according to Hughston's functional and radiological criteria. After an average follow-up of 24 months, algoneurodystrophy was reported in 5 cases with a single case of haemarthrosis. A net ICRS score improvement was observed with a mean increasing from 54% to 74% on the follow-up visit. Most of patients were satisfied or very satisfied (82.9%). The elements of good prognosis recognized in our study included: a mean time between symptom onset and surgery of less of 18 months, having deep lesions with a diameter less than 02 cm and having lesions in the internal condyle. The treatment of cartilage loss is necessarily based on the correction of its direct and indirect causes namely the morphotype, the laxity and meniscus capital. No consensus in the decision-making was reached and no one could confirm the superiority of a technique in relation to the other but we can say that cartilage defect which sizes from 2 to 4 cm² may be the best indication for mosaic arthroplasty.

Outcomes Associated with Return to Sports Following Osteochondral Allograft Transplant in the Knee: a Scoping Review

PURPOSE OF REVIEW

The purposes of this review were to report the currently validated outcomes for OCA transplant patients, discuss the benefits and challenges associated with "return to sports" as an outcome measure, and summarize the currently available data on patients' ability to return to sports after OCA transplant.

RECENT FINDINGS

College athletes may take less time than professionals to return to basketball, but there are many factors that can influence this timeframe. Player productivity is decreased ~ 40% and future career length is only 1 to 2 years following return to play. When evaluating all OCA transplant patients, 75-88% of patients return to sport and 38-80% return to their previous level of play at approximately 8-10 months following surgery. Overall graft failure rates are low (0-9.4%) but are based on limited short- to medium-term data. Data on the return to professional and college sports after OCA transplant is limited. Surgeons should consider collecting patient outcomes across multiple domains and contributing data to aggregate databases to allow for better quality outcome data to be reported.

Autologous Chondrocyte Implantation "Segmental-Sandwich" Technique for Deep Osteochondral Defects in the Knee: Clinical Outcomes and Correlation With Magnetic Resonance Imaging Findings

Background

Symptomatic osteochondral defects are difficult to manage, especially in patients with deep (>8-10 mm) empty defects. The restoration of articular congruence is crucial to avoid the progression to osteoarthritis (OA).

Purpose

To describe the autologous chondrocyte implantation (ACI) "segmental-sandwich" technique for restoration of the osteochondral unit and to evaluate midterm outcomes in patients treated with this procedure. Correlations between magnetic resonance imaging (MRI) and radiographic findings with outcomes were assessed.

Study Design

Case series; Level of evidence, 4.

Methods

Outcomes were evaluated for a consecutive cohort of 15 patients with symptomatic deep (>8 mm) osteochondral lesions who underwent autologous bone grafting plus the ACI segmental-sandwich technique performed by a single surgeon between 2003 and 2011. Patients with a minimum 2-year follow-up were included. All patients completed validated clinical outcome scales and a patient satisfaction survey. The Kellgren-Lawrence (K-L) grade was assessed for the progression to OA. The repair site was evaluated with the MOCART (magnetic resonance observation of cartilage repair tissue) score. Filling and tissue characteristics of the bone defect were analyzed with MRI.

Results

All patients (mean age at surgery, 31.0 ± 9.1 years) were available for follow-up (mean follow-up, 7.8 ± 3.0 years; range, 2-15 years). The mean chondral lesion size was 6.0 ± 3.5 cm² (range, 1.5-13.5 cm²), with a mean bone defect area of 1.7 cm² (27%-40% of overall surface area treated by ACI) and depth of 1.0 cm. All patients had successful clinical outcomes, and all functional scores improved significantly (P < .05). Patients reported a very high satisfaction rate (93%). The K-L grade demonstrated no significant progression to OA over a mean follow-up of 4.7 years. For 12 patients with MRI results available, the mean MOCART score at a mean of 3.3 years was 64.2 ± 19.9, with complete or near-complete (≥75% of defect volume) chondral defect filling (83%) and complete integration to adjacent cartilage (83%). Bone defects were completely filled in 83% of patients.

Conclusion

The ACI segmental-sandwich technique provides significant functional improvements at midterm follow-up and excellent survival rates. This unique treatment allows for the resurfacing of cartilage defects and the repair of underlying segmental bone lesions.

Fabrication and mechanical characterization of 3D printed vertical uniform and gradient scaffolds for bone and osteochondral tissue engineering

Recent developments in 3D printing (3DP) research have led to a variety of scaffold designs and techniques for osteochondral tissue engineering; however, the simultaneous incorporation of multiple types of gradients within the same construct remains a challenge. Herein, we describe the fabrication and mechanical characterization of porous poly(ε-caprolactone) (PCL) and PCL-hydroxyapatite (HA) scaffolds with incorporated vertical porosity and ceramic content gradients via a multimaterial extrusion 3DP system. Scaffolds of 0 wt% HA (PCL), 15 wt% HA (HA15), or 30 wt% HA (HA30) were fabricated with uniform composition and porosity (using 0.2 mm, 0.5 mm, or 0.9 mm on-center fiber spacing), uniform composition and gradient porosity, and gradient composition (PCL-HA15-HA30) and porosity. Micro-CT imaging and porosity analysis demonstrated the ability to incorporate both vertical porosity and pore size gradients and a ceramic gradient, which collectively recapitulate gradients found in native osteochondral tissues. Uniaxial compression testing demonstrated an inverse relationship between porosity, ϕ, and compressive modulus, E, and yield stress, σy, for uniform porosity scaffolds, however, no differences were observed as a result of ceramic incorporation. All scaffolds demonstrated compressive moduli within the appropriate range for trabecular bone, with average moduli between 86 ± 14-220 ± 26 MPa. Uniform porosity and pore size scaffolds for all ceramic levels had compressive moduli between 205 ± 37-220 ± 26 MPa, 112 ± 13-118 ± 23 MPa, and 86 ± 14-97 ± 8 MPa respectively for porosities ranging between 14 ± 4-20 ± 6%, 36 ± 3-43 ± 4%, and 54 ± 2-57 ± 2%, with the moduli and yield stresses of low porosity scaffolds being significantly greater (p < 0.05) than those of all other groups. Single (porosity) gradient and dual (composition/porosity) gradient scaffolds demonstrated compressive properties similar (p > 0.05) to those of the highest porosity uniform scaffolds (porosity gradient scaffolds 98 ± 23-107 ± 6 MPa, and 102 ± 7 MPa for dual composition/porosity gradient scaffolds), indicating that these properties are more heavily influenced by the weakest section of the gradient. The compression data for uniform scaffolds were also readily modeled, yielding scaling laws of the form E ∼ (1 - ϕ)1.27 and σy ∼ (1 - ϕ)1.37, which demonstrated that the compressive properties evaluated in this study were well-aligned with expectations from previous literature and were readily modeled with good fidelity independent of polymer scaffold geometry and ceramic content. All uniform scaffolds were similarly deformed and recovered despite different porosities, while the large-pore sections of porosity gradient scaffolds were significantly more deformed than all other groups, indicating that porosity may not be an independent factor in determining strain recovery. Moving forward, the technique described here will serve as the template for more complex multimaterial constructs with bioactive cues that better match native tissue physiology and promote tissue regeneration. STATEMENT OF SIGNIFICANCE: This manuscript describes the fabrication and mechanical characterization of "dual" porosity/ceramic content gradient scaffolds produced via a multimaterial extrusion 3D printing system for osteochondral tissue engineering. Such scaffolds are designed to better address the simultaneous gradients in architecture and mineralization found in native osteochondral tissue. The results of this study demonstrate that this technique may serve as a template for future advances in 3D printing technology that may better address the inherent complexity in such heterogeneous tissues.

Osteochondral repair using scaffolds with gradient pore sizes constructed with silk fibroin, chitosan, and nano-hydroxyapatite

Background

One of the main problems associated with the development of osteochondral reparative materials is that the accurate imitation of the structure of the natural osteochondral tissue and fabrication of a suitable scaffold material for osteochondral repair are difficult. The long-term outcomes of single- or bilayered scaffolds are often unsatisfactory because of the absence of a progressive osteochondral structure. Therefore, only scaffolds with gradient pore sizes are suitable for osteochondral repair to achieve better proliferation and differentiation of the stem cells into osteochondral tissues to complete the repair of defects.

Methods

A silk fibroin (SF) solution, chitosan (CS) solution, and nano-hydroxyapatite (nHA) suspension were mixed at the same weight fraction to obtain osteochondral scaffolds with gradient pore diameters by centrifugation, freeze-drying, and chemical cross-linking.

Results

The scaffolds prepared in this study are confirmed to have a progressive structure starting from the cartilage layer to bone layer, similar to that of the normal osteochondral tissues. The prepared scaffolds are cylindrical in shape and have high internal porosity. The structure consists of regular and highly interconnected pores with a progressively increasing pore distribution as well as a progressively changing pore diameter. The scaffold strongly absorbs water, and has a suitable degradation rate, sufficient space for cell growth and proliferation, and good resistance to compression. Thus, the scaffold can provide sufficient nutrients and space for cell growth, proliferation, and migration. Further, bone marrow mesenchymal stem cells seeded onto the scaffold closely attach to the scaffold and stably grow and proliferate, indicating that the scaffold has good biocompatibility with no cytotoxicity.

Conclusion

In brief, the physical properties and biocompatibility of our scaffolds fully comply with the requirements of scaffold materials required for osteochondral tissue engineering, and they are expected to become a new type of scaffolds with gradient pore sizes for osteochondral repair.

Biofabrication for osteochondral tissue regeneration: bioink printability requirements

Biofabrication allows the formation of 3D scaffolds through a precise spatial control. This is of foremost importance when aiming to mimic heterogeneous and anisotropic architecture, such as that of the osteochondral tissue. Osteochondral defects are a supreme challenge for tissue engineering due to the compositional and structural complexity of stratified architecture and contrasting biomechanical properties of the cartilage-bone interface. This review highlights the advancements and retreats witnessed by using developed bioinks for tissue regeneration, taking osteochondral tissue as a challenging example. Methods, materials and requirements for bioprinting were discussed, highlighting the pre and post-processing factors that researchers should consider towards the development of a clinical treatment.

Favourable long-term functional and radiographical outcome after osteoautograft transplantation surgery of the knee: a minimum 10-year follow-up

PURPOSE

The aim of this study was to assess the progression of radiological cartilage changes and to document the functional, long-term results during a follow-up of 10 years after osteoautograft transplantation (OAT) knee surgery.

METHODS

The study was a retrospective analysis of all patients who underwent OAT at Turku University Hospital from 1999 to 2007. Pre- and postoperative cartilage changes were estimated based on standardised radiographs. The extent of osteoarthritis (OA) was graded according to the Kellgren-Lawrence scale. Clinical outcomes were evaluated with the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire.

RESULTS

A total of 60 patients (64 knees) with a median age of 30 years (range 14-62) were included. The median follow-up was 140 months (range 47-205). Of the 64 knees examined, 14 (22%) had a traumatic chondral lesion and 50 (78%) had osteochondritis dissecans (OCD). Preoperatively, 71% of the patients had Kellgren-Lawrence grades of 0-1; during the follow-up period, 50% of the patients showed radiographical progression of OA. OA progressed most significantly in patients with normal preoperative Kellgren-Lawrence grades (p = 0.0003). Patients with no progression in joint space narrowing had statistically significantly better overall KOOS (p = 0.02) than patients whose Kellgren-Lawrence grades worsened. Patients with defect sizes > 3.0 cm² scored statistically significantly better in all subscales than patients with smaller defect sizes (p = 0.02). Patients with OCD had statistically significantly better KOOS than patients with chondral defects (p = 0.008).

CONCLUSIONS

OAT surgery for treating patients with cartilage defects of the knee had good clinical results after a mean follow-up of 11 years. Radiological analyses revealed a progression of cartilage degeneration in 50% of the operated knees. Patients with no progression of the degenerative changes scored statistically significantly better on the KOOS self-assessment test. These results indicate that OAT surgery appears to be a reasonable therapeutic option to restore knee function in patients with cartilage lesions.

LEVEL OF EVIDENCE

IV.

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.

Orthopedic Surgical Options for Joint Cartilage Repair and Restoration

The limited natural capacity for articular cartilage to regenerate has led to a continuously broadening array of surgical interventions. Used once patients' symptoms are not relieved by nonoperative management, these share the goals of joint preservation and restoration. Techniques include bone marrow stimulation, whole-tissue transplantation, and cell-based strategies, each with its own variations. Many of these interventions are performed arthroscopically or with extended-portal techniques. Indications, operative techniques, unique benefits, and limitations are presented.

Return to sport after the surgical management of articular cartilage lesions in the knee: a meta-analysis

PURPOSE

Optimal surgical treatment of chondral defects in an athletic population remains highly controversial and has yet to be determined. The purpose of this review was to (1) report data on return to sport and (2) compare activity and functional outcome measures following various cartilage restoration techniques.

METHODS

A comprehensive review was performed for studies with return-to-sport outcomes after microfracture (MFX), osteochondral autograft transfer (OAT), osteochondral allograft transplantation (OCA), and autologous chondrocyte implantation (ACI). All studies containing return-to-sport participation with minimum 2-year post-operative activity-based outcomes were included. A meta-analysis comparing rate of return to sport between each surgical intervention was conducted using a random-effects model.

RESULTS

Forty-four studies met inclusion criteria (18 Level I/II, 26 Level III/IV). In total, 2549 patients were included (1756 M, 793 F) with an average age of 35 years and follow-up of 47 months. Return to sport at some level was 76 % overall, with highest rates of return after OAT (93 %), followed by OCA (88 %), ACI (82 %), and MFX (58 %). Osteochondral autograft transfer showed the fastest return to sports (5.2 ± 1.8 months) compared to 9.1 ± 2.2 months for MFX, 9.6 ± 3.0 months for OCA and 11.8 ± 3.8 months for ACI (P < 0.001). A meta-regression was conducted due to heterogeneity in preoperative factors such as patient age, lesion size, and preoperative Tegner score. None of these factors were found to be significant determinants for rate of return to sport.

CONCLUSION

In conclusion, in this meta-analysis of 2549 athletes, cartilage restoration surgery had a 76 % return to sport at mid-term follow-up. Osteochondral autograft transfer offered a faster recovery and appeared to have a higher rate of return to preinjury athletics, but heterogeneity in lesion size, athlete age, and concomitant surgical procedures are important factors to consider when assessing individual athletes. This study reports on the rate of return to sport in athletes undergoing various procedures for symptomatic chondral defects.

LEVEL OF EVIDENCE

IV.

[When is cartilage repair successful?]

Focal cartilage lesions are a cause of long-term disability and morbidity. After cartilage repair, it is crucial to evaluate long-term progression or failure in a reproducible, standardized manner. This article provides an overview of the different cartilage repair procedures and important characteristics to look for in cartilage repair imaging. Specifics and pitfalls are pointed out alongside general aspects. After successful cartilage repair, a complete, but not hypertrophic filling of the defect is the primary criterion of treatment success. The repair tissue should also be completely integrated to the surrounding native cartilage. After some months, the transplants signal should be isointense compared to native cartilage. Complications like osteophytes, subchondral defects, cysts, adhesion and chronic bone marrow edema or joint effusion are common and have to be observed via follow-up. Radiological evaluation and interpretation of postoperative changes should always take the repair method into account.

Molecular Validation of Chondrogenic Differentiation and Hypoxia Responsiveness of Platelet-Lysate Expanded Adipose Tissue-Derived Human Mesenchymal Stromal Cells

OBJECTIVE

To determine the optimal environmental conditions for chondrogenic differentiation of human adipose tissue-derived mesenchymal stromal/stem cells (AMSCs). In this investigation we specifically investigate the role of oxygen tension and 3-dimensional (3D) culture systems.

DESIGN

Both AMSCs and primary human chondrocytes were cultured for 21 days in chondrogenic media under normoxic (21% oxygen) or hypoxic (2% oxygen) conditions using 2 distinct 3D culture methods (high-density pellets and poly-ε-caprolactone [PCL] scaffolds). Histologic analysis of chondro-pellets and the expression of chondrocyte-related genes as measured by reverse transcriptase quantitative polymerase chain reaction were used to evaluate the efficiency of differentiation.

RESULTS

AMSCs are capable of expressing established cartilage markers including COL2A1, ACAN, and DCN when grown in chondrogenic differentiation media as determined by gene expression and histologic analysis of cartilage markers. Expression of several cartilage-related genes was enhanced by low oxygen tension, including ACAN and HAPLN1. The pellet culture environment also promoted the expression of hypoxia-inducible cartilage markers compared with cells grown on 3D scaffolds.

CONCLUSIONS

Cell type-specific effects of low oxygen and 3D environments indicate that mesenchymal cell fate and differentiation potential is remarkably sensitive to oxygen. Genetic programming of AMSCs to a chondrocytic phenotype is effective under hypoxic conditions as evidenced by increased expression of cartilage-related biomarkers and biosynthesis of a glycosaminoglycan-positive matrix. Lower local oxygen levels within cartilage pellets may be a significant driver of chondrogenic differentiation.

Selective laser sintering scaffold with hierarchical architecture and gradient composition for osteochondral repair in rabbits

Osteochondral defects cannot be adequately self-repaired due to the presence of the sophisticated hierarchical structure and the lack of blood supply in cartilage. Thus, one of the major challenges remaining in this field is the structural design of a biomimetic scaffold that satisfies the specific requirements for osteochondral repair. To address this hurdle, a bio-inspired multilayer osteochondral scaffold that consisted of the poly(ε-caprolactone) (PCL) and the hydroxyapatite (HA)/PCL microspheres, was constructed via selective laser sintering (SLS) technique. The SLS-derived scaffolds exhibited an excellent biocompatibility to support cell adhesion and proliferation in vitro. The repair effect was evaluated by implanting the acellular multilayer scaffolds into osteochondral defects of a rabbit model. Our findings demonstrated that the multilayer scaffolds were able to induce articular cartilage formation by accelerating the early subchondral bone regeneration, and the newly formed tissues could well integrate with the native tissues. Consequently, the current study not only achieves osteochondral repair, but also suggests a promising strategy for the fabrication of bio-inspired multilayer scaffolds with well-designed architecture and gradient composition via SLS technique.

Osteochondral Autologous Transplantation

Osteochondral autologous transplantation (OAT) is a treatment strategy for small and medium sized focal articular cartilage defects in the knee. This article reviews the indications, surgical techniques, outcomes, and limitations of OAT for the management of symptomatic chondral and osteochondral lesions in the knee joint.

Retropatellar Accessory Portals for Improved Access to the Patella: Anatomic Description and Evaluation of Safety

Background:

Standard knee arthroscopy portals are frequently used to address retropatellar chondral pathology. Alternative portals may offer a safe and simple substitute, particularly when reaching the base of deep lesions is required.

Purpose:

To describe and assess the safety of accessory retropatellar portals.

Study Design:

Descriptive laboratory study.

Methods:

An anatomic study was performed on 10 fresh-frozen cadaveric knees. Medial and lateral retropatellar portals were created, and the distance to adjacent neurovascular structures (common peroneal nerve [CPN] and infrapatellar branch of the saphenous nerve [IPBSN]) and bony landmarks (medial and lateral epicondyles and margins of the midpatella) was recorded. A clinical account of portal use is provided through a retrospective chart review.

Results:

The medial and lateral retropatellar portals were a mean 15.8 ± 15.5 mm and 53.8 ± 7.2 mm from the IPBSN and CPN, respectively. No nerves were contacted in any specimens. Clinically, the portals have been used in 109 cases over a 7-year period without complication.

Conclusion:

The high level of IPBSN variability poses some risk to medial portal use; however, there is little to no risk laterally. Clinical experience with portals suggests that they can be used safely. We recommend careful blunt dissection to minimize chance of iatrogenic nerve injury.

Clinical Relevance:

Retropatellar portals may offer improved access to chondral lesions of the patella, thereby safely allowing one to maintain an arthroscopic approach.

Chondral Lesions of the Hip

The treatment of chondral hip injuries is challenging. However, for young patients with hip disorders, orthopedic surgeons now have the opportunity to intervene early in the development of debilitating joint disease. As understanding of the hip joint continues to evolve, more effective treatment strategies are emerging. There are several reportedly successful options for surgical treatment. This article reviews the clinical presentation of chondral injuries and the surgical modalities, arthroscopic and open, available to treat them.

Long-term Outcomes After Osteochondral Autograft Transfer: A Systematic Review at Mean Follow-up of 10.2 Years

PURPOSE

To evaluate (1) activity level and knee function, (2) reoperation and failure rates, and (3) risk factors for reoperation and failure of osteochondral autograft transfer (OAT) at minimum long-term follow-up.

METHODS

A comprehensive review was performed for long-term outcomes after OAT. Studies reported on activity-based outcomes (Tegner Activity Scale) and clinical outcomes (Lysholm score and International Knee Documentation Committee score). Reoperation and failure rates, as defined by the publishing authors, were recorded for each study. Modified Coleman Methodology Scores were calculated to assess study methodological quality.

RESULTS

Ten studies with a total of 610 patients with an average age of 27.0 years at the time of surgery and a mean follow-up of 10.2 years were included. The mean defect size was 2.6 cm(2) (range, 0.9 to 20.0 cm(2)). The mean duration of symptoms before surgery was 4.8 years. From preoperative to final follow-up, International Knee Documentation Committee scores and Lysholm scores improved significantly by 42.4 (95% confidence interval [CI], 31.8 to 53.1, P < .001) and 21.1 (95% CI, 12.2 to 30.0, P < .01), respectively. Tegner score did not improve significantly (0.76, 95% CI, -0.83 to 2.36, P = .35). Overall failure rate was 28% and reoperation rate was 19%. Increased age, previous surgery, and defect size positively correlated with increased risk of failure. Concomitant surgical procedures negatively correlated with failure rate.

CONCLUSIONS

Overall, OAT showed successful outcomes in 72% of patients at long-term follow-up. Increased age, previous surgery, and defect size correlated positively with failure rate, whereas success improved with concomitant surgical procedures. Nonetheless, this systematic review is limited by heterogeneity in a surgical technique, lesion and patient characteristics, and reporting of nonstandardized outcome measures.

LEVEL OF EVIDENCE

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

Platelet-rich plasma increases transforming growth factor-beta1 expression at graft-host interface following autologous osteochondral transplantation in a rabbit model

AIM: To explore the effect of platelet-rich plasma on protein expression patterns of transforming growth factor-beta1 (TGF-β1) in cartilage following autologous osteochondral transplantation (AOT) in a rabbit knee cartilage defect model.

METHODS: Twelve New Zealand white rabbits received bilateral AOT. In each rabbit, one knee was randomized to receive an autologous platelet rich plasma (PRP) injection and the contralateral knee received saline injection. Rabbits were euthanized at 3, 6 and 12 wk post-operatively. Articular cartilage sections were stained with TGF-β1 antibody. Histological regions of interest (ROI) (left, right and center of the autologous grafts interfaces) were evaluated using MetaMorph. Percentage of chondrocytes positive for TGF-β1 was then assessed.

RESULTS: Percentage of chondrocytes positive for TGF-β1 was higher in PRP treated knees for selected ROIs (left; P = 0.03, center; P = 0.05) compared to control and was also higher in the PRP group at each post-operative time point (P = 6.6 × 10^-4, 3.1 × 10^-4 and 7.3 × 10^-3 for 3, 6 and 12 wk, respectively). TGF-β1 expression was higher in chondrocytes of PRP-treated knees (36% ± 29% vs 15% ± 18%) (P = 1.8 × 10^-6) overall for each post-operative time point and ROI.

CONCLUSION: Articular cartilage of rabbits treated with AOT and PRP exhibit increased TGF-β1 expression compared to those treated with AOT and saline. Our findings suggest that adjunctive PRP may increase TGF-β1 expression, which may play a role in the chondrogenic effect of PRP in vivo.

UPDATING ON DIAGNOSIS AND TREATMENT OF CHONDRAL LESION OF THE KNEE

The treatment of chondral knee injuries remains a challenge for the orthopedic surgeon, mainly owing to the characteristics of the cartilage tissue, which promote low potential for regeneration. Chondral lesions can be caused by metabolic stimulation, or by genetic, vascular and traumatic events, and are classified according to the size and thickness of the affected cartilage. Clinical diagnosis can be difficult, especially due to insidious symptoms. Additional tests, as Magnetic Resonance Imaging (MRI), may be needed. The treatment of these lesions usually starts with non-operative management. Surgery should be reserved for patients with detached chondral fragments, blocked range of motion, or the failure of non-operative treatment. The surgical techniques used for the treatment of partial thickness defects are Debridement and Ablation. These techniques aim to improve symptoms, since they do not restore normal structure and function of the cartilage. For full-thickness defects (osteochondral lesion), available treatments are Abrasion, Drilling, Microfracture, Osteochondral Autologous and Allogeneic Transplantation, and biological techniques such as the use of Autologous Chondrocyte Transplantation, Minced Cartilage and stem cells.

Chitosan enriched three-dimensional matrix reduces inflammatory and catabolic mediators production by human chondrocytes

This in vitro study investigated the metabolism of human osteoarthritic (OA) chondrocytes encapsulated in a spherical matrix enriched of chitosan. Human OA chondrocytes were encapsulated and cultured for 28 days either in chitosan-alginate beads or in alginate beads. The beads were formed by slowly passing dropwise either the chitosan 0.6%-alginate 1.2% or the alginate 1.2% solution through a syringe into a 102 mM CaCl2 solution. Beads were analyzed histologically after 28 days. Interleukin (IL)-6 and -8, prostaglandin (PG) E2, matrix metalloproteinases (MMPs), hyaluronan and aggrecan were quantified directly in the culture supernatant by specific ELISA and nitric oxide (NO) by using a colorimetric method based on the Griess reaction. Hematoxylin and eosin staining showed that chitosan was homogeneously distributed through the matrix and was in direct contact with chondrocytes. The production of IL-6, IL-8 and MMP-3 by chondrocytes significantly decreased in chitosan-alginate beads compared to alginate beads. PGE2 and NO decreased also significantly but only during the first three days of culture. Hyaluronan and aggrecan production tended to increase in chitosan-alginate beads after 28 days of culture. Chitosan-alginate beads reduced the production of inflammatory and catabolic mediators by OA chondrocytes and tended to stimulate the synthesis of cartilage matrix components. These particular effects indicate that chitosan-alginate beads are an interesting scaffold for chondrocytes encapsulation before transplantation to repair cartilage defects.

Cartilage issues in football-today's problems and tomorrow's solutions

Articular cartilage injury is prevalent in football players and results from chronic joint stress or acute traumatic injuries. Articular cartilage injury can often result in progressive painful impairment of joint function and limit sports participation. Management of articular cartilage injury in athletes aims to return the player to competition, and requires effective and durable joint surface restoration that resembles normal hyaline articular cartilage that can withstand the high joint stresses of football. Existing articular cartilage repair techniques can return the athlete with articular cartilage injury to high-impact sports, but treatment does not produce normal articular cartilage, and this limits the success rate and durability of current cartilage repair in athletes. Novel scientific concepts and treatment techniques that apply modern tissue engineering technologies promise further advancement in the treatment of these challenging injuries in the high demand athletic population. We review the current knowledge of cartilage injury pathophysiology, epidemiology and aetiology, and outline existing management algorithms, developing treatment options and future strategies to manage articular cartilage injuries in football players.

Treatment of osteochondral lesions in the elbow: results after autologous osteochondral transplantation

BACKGROUND

Osteochondral lesions in the elbow still remain a challenging field of surgery. In recent years promising clinical results were described for the osteochondral transplantation technique. The aim of this retrospective study was to evaluate the clinical and radiological outcome in the mid-term follow-up of a large cohort of patients following osteochondral transplantation in the elbow.

METHODS

18 patients with advanced osteochondral lesions of the elbow treated by autologous osteochondral autograft cylinders and a minimum follow-up of 36 months were included in the study. The Broberg-Morrey score (BMS) and the American Shoulder and Elbow score (ASES) were used to assess elbow function and pain, respectively. The joint status was analyzed using plain radiographs and MRI scans taken from all patients at recent follow-up. In addition, the ipsilateral knee joint was examined for donor-site morbidity using the Lysholm knee score.

RESULTS

14 patients were evaluated with a mean follow-up of 7 years (range 3-14 years). The mean BMS was 95.1 (range 72-100) points. The ASES score also showed promising results: pain at worst 1.5 (range 0-5) points, pain at rest 0.4 (range 0-5) points, pain lifting loads 2.8 (range 0-8) points, repetitive movement pain 1.5 (range 0-8) points. The range of motion of the injured elbow was free and equal to the contralateral side. Signs of osteoarthritis could be found on plain radiographs in three patients. The MRIs at follow-up showed graft viability in all patients. However, a slight incongruency of the chondral surface could be detected in two patients. The average Lysholm score was 90.9 (range 0-70) points.

CONCLUSIONS

Osteochondral transplantation in the elbow leads to both clinical and radiographic good-to-excellent mid-term results and therefore represents a reasonable treatment option for advanced osteochondral lesions in the elbow.

LEVEL OF EVIDENCE

Retrospective study; Therapeutic Level IV.