Autologous osteochondral mosaicplasty in osteochondritis dissecans of the patella in adolescents

Osteochondral Autograft Transplantation for Symptomatic Full-thickness Patellar Cartilage Defects in Adolescents

BACKGROUND

This study aimed to review the clinical, radiographic, and magnetic resonance imaging (MRI) outcomes of osteochondral autograft transplantation applied to patellar cartilage lesions of patients under 18 years of age.

METHODS

Data from nine consecutive patients were retrospectively analyzed for indications, preoperative complications, and clinical-radiographic outcomes. Patients were clinically evaluated using the Pedi-IKDC and Lysholm scores. In addition, return to sports and knee pain were assessed. MRI evaluation included an analysis of osteochondral graft integration using the magnetic resonance observation of cartilage repair tissue 2.0 score and radiographic classification of osteoarthritis using the Kellgren-Lawrence system.

RESULTS

Nine patients (9 knees, 6 males) with a mean age of 14 years (SD: 1.7, range; 11 to 17 y) were analyzed. Lesions were located on the medial facet (N=5), lateral facet (N=3), and central ridge of the patella (N=1). One or 2 cylindrical osteochondral grafts were transplanted, with a median diameter of 9 mm (range: 8 to 10 mm). The average lesion size was 102.9 mm2. At a mean follow-up of 45.1 months (range: 23 to 117 mo), the mean Pedi-IKDC score was 89.2 (SD: 9.8), and the Lysholm score was 94.4 (SD: 4.8). Patients returned to sports in an average of 7.3 months (SD: 2, range: 6 to 12 mo). MRI of 8 patients showed osteochondral graft integration with a mean magnetic resonance observation of cartilage repair tissue 2.0 score of 86.9 (SD: 7, range: 80 to 100). Six knees showed Kellgren-Lawrence grade 0 joint space on radiographs, and 3 showed grade 1. Eight patients were asymptomatic at the last follow-up, and 1 reported occasional mild pain with intense physical activity. One patient developed arthrofibrosis, requiring arthroscopic lysis of adhesions and manipulation.

CONCLUSION

Osteochondral autograft transplantation is a safe and effective technique for treating symptomatic patellar full-thickness chondral lesions in adolescents. Long-term follow-up studies will determine whether the affected area maintains structural and functional integrity over time.

LEVEL OF EVIDENCE

Level IV-therapeutic study.

Cartilage Restoration for Isolated Patellar Chondral Defects: An Updated Systematic Review

Background

Patellar chondral lesions can be particularly challenging to manage in younger and more active populations.

Purpose

To synthesize, organize, and summarize the results and complication rates of various patellar cartilage restoration techniques.

Study Design

Systematic review; Level of evidence, 4.

Methods

We performed this systematic review according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using the Medline, Embase, Scopus, and Cochrane databases. Studies were included that reported on surgical treatment of patellar chondral defects with ≥5 patients and 12 months of follow-up data. Relevant demographic data from the included studies were extracted, and patient-reported outcome scores, visual analog scale for pain results, return-to-sport rate, complications, and concomitant procedures were documented.

Results

There were 24 studies that met the inclusion criteria, with a total of 575 patients (male, n = 239; female, n = 336). In total, 6 surgical techniques were utilized. In 9 studies, the surgical procedure of choice was osteochondral autograft transplantation (OAT); 8 studies evaluated autologous chondrocyte implantation (ACI); 3 evaluated advanced microfracture/autologous matrix-induced chondrogenesis; 1 evaluated osteochondral allograft transplantation (OCA); 1 evaluated particulate juvenile articulated cartilage; and 2 evaluated a synthetic osteochondral graft. No uniform functional outcome score or assessment was utilized across studies. OAT was predominantly used for smaller chondral lesions (<2 cm²) and demonstrated minimal complication rates and satisfactory outcome scores. Advanced microfracture techniques showed promise, with improvement in outcome scores and zero complications. Matrix-induced ACI consistently exhibited higher mean improvement in the measured outcome scores and resulted in fewer complications when compared with previous generations of ACI.

Conclusion

OAT and ACI were the most studied procedures for isolated patellar chondral defects. Advanced microfracture techniques showed promise, but indications (ie, size) and variability in techniques need to be elucidated in higher-level studies. Further prospective studies comparing OCA and matrix-induced ACI for larger patellar defects are necessary to determine the superior technique.

Seamless and early gap healing of osteochondral defects by autologous mosaicplasty combined with bioactive supramolecular nanofiber-enabled gelatin methacryloyl (BSN-GelMA) hydrogel

Autologous mosaicplasty is a common approach used to treat osteochondral defects in clinical practice. Gap integration between host and transplanted plugs requires bone tissue reservation and hyaline cartilage regeneration without uneven surface, graft necrosis and sclerosis. However, poor gap integration is a serious concern, which eventually leads to deterioration of joint function. To deal with such complications, this study has developed a strategy to effectively enhance integration of the gap region following mosaicplasty by applying injectable bioactive supramolecular nanofiber-enabled gelatin methacryloyl (GelMA) hydrogel (BSN-GelMA). A rabbit osteochondral defect model demonstrated that BSN-GelMA achieved seamless osteochondral healing in the gap region between plugs of osteochondral defects following mosaicplasty, as early as six weeks. Moreover, the International Cartilage Repair Society score, histology score, glycosaminoglycan content, subchondral bone volume, and collagen II expression were observed to be the highest in the gap region of BSN-GelMA treated group. This improved outcome was due to bio-interactive materials, which acted as tissue fillers to bridge the gap, prevent cartilage degeneration, and promote graft survival and migration of bone marrow mesenchymal stem cells by releasing bioactive supramolecular nanofibers from the GelMA hydrogel. This study provides a powerful and applicable approach to improve gap integration after autologous mosaicplasty. It is also a promising off-the-shelf bioactive material for cell-free in situ tissue regeneration.

•

A novel strategy that can effectively enhance post-mosaicplasty interstitial integration was developed.

•

The bioactive supramolecular nanofibers (BSN) exhibited comparable bioactivity to insulin-like growth factor-1 (IGF-1).

•

The BSN-GelMA hydrogel is a promising off-the-shelf bioactive material for cell-free in situ tissue regeneration.

Safety and Efficacy of Matrix-Associated Autologous Chondrocyte Implantation With Spheroids for Patellofemoral or Tibiofemoral Defects: A 5-Year Follow-up of a Phase 2, Dose-Confirmation Trial

Background:

Matrix-associated autologous chondrocyte implantation (ACI) is a well-established treatment for cartilage defects. High-level evidence at midterm follow-up is limited, especially for ACI using spheroids (spherical aggregates of ex vivo expanded human autologous chondrocytes and self-synthesized extracellular matrix).

Purpose:

To assess the safety and efficacy of 3-dimensional matrix-associated ACI using spheroids to treat medium to large cartilage defects on different locations in the knee joint (patella, trochlea, and femoral condyle) at 5-year follow-up.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

A total of 75 patients aged 18 to 50 years with medium to large (4-10 cm²), isolated, single cartilage defects, International Cartilage Repair Society grade 3 or 4, were randomized on a single-blind basis to treatment with ACI at 1 of 3 dose levels: 3 to 7, 10 to 30, or 40 to 70 spheroids/cm² of defect size. Outcomes were assessed via changes from baseline Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee score, and modified Lysholm assessments at 1- and 5-year follow-up. Structural repair was evaluated using MOCART (magnetic resonance observation of cartilage repair tissue) score. Treatment-related adverse events were assessed up to 5 years for all patients. The overall KOOS at 12 months was assessed for superiority versus baseline in a 1-sample, 2-sided t test.

Results:

A total of 73 patients were treated: 24 in the low-dose group, 25 in the medium-dose group, and 24 in the high-dose group. The overall KOOS improved from 57.0 ± 15.2 at baseline to 73.4 ± 17.3 at 1-year follow-up (P < .0001) and 76.9 ± 19.3 at 5-year follow-up (P < .0001), independent of the applied dose. The different defect locations (patella, trochlea, and weightbearing part of the femoral condyles; P = .2216) and defect sizes (P = .8706) showed comparable clinical improvement. No differences between the various doses were observed. The overall treatment failure rate until 5 years was 4%. Most treatment-related adverse events occurred within the first 12 months after implantation, with the most frequent adverse reactions being joint effusion (n = 71), arthralgia (n = 14), and joint swelling (n = 9).

Conclusion:

ACI using spheroids was safe and effective for defect sizes up to 10 cm² and showed maintenance of efficacy up to 5 years for all 3 doses that were investigated.

Registration:

NCT01225575 (ClinicalTrials.gov identifier); 2009-016816-20 (EudraCT number).

What Do We Currently Know About Patellofemoral Osteochondritis Dissecans?

OBJECTIVE

Knee osteochondritis dissecans (OCD) is a still poorly understood pathological condition of the articular subchondral bone and its overlying cartilage. Patellofemoral involvement accounts for less than 1% of cases; tibial plateau and multifocal involvement is an even rarer instance. The purpose of this study is to review what is currently known about patellofemoral OCD (PF-OCD) and to present an unusual case of PF-OCD which progressed to become multifocal in an adult female patient.

METHODS

A comprehensive literature search was conducted on PubMed/Medline, Cochrane, Embase, Web of Science, and Scopus databases on September 2021 for all levels of evidence and English language. After duplicate removal, 234 papers pertaining to PF-OCD were retrieved. Thirty-nine studies met inclusion criteria and were included in the review. As an example, a unique case of delamination of patellar cartilage consistent with PF-OCD with progressive involvement of trochlea and both tibial plateau in a 35-year-old woman is also presented.

RESULTS

PF-OCD is a rare localization of knee OCD. Two hundred eighty-eight cases have been reported in the literature to date. Mean age at time of diagnosis was 16 years and the location could also be bilateral and multifocal. The etiology is still debated but traumatic, vascular, and hereditary mechanisms are likely. Management mirrors that of classical OCD.

CONCLUSIONS

PF-OCD is an uncommon cause of anterior knee pain but should be considered even when physeal plates are closed. Current available evidence on treatment is of low quality, based on single case reports or small retrospective case series.

Good clinical outcomes after patellar cartilage repair with no evidence for inferior results in complex cases with the need for additional patellofemoral realignment procedures: a systematic review

PURPOSE

Focal, patellar cartilage defects are a challenging problem as most cases have an underlying multifactorial pathogenesis. This systematic review of current literature analysed clinical results after regenerative cartilage repair of the patella with a special focus on the assessment and treatment of existing patellofemoral malalignment.

METHODS

A systematic review was conducted to identify articles reporting clinical results after cartilage regenerative surgeries of the patella using the PubMed and Scopus database. The extracted data included patient-reported outcome measures (PROMS) and whether cartilage repair was performed alone or in combination with concomitant surgeries of underlying patellofemoral co-pathologies. In cases of isolated cartilage repair, specific exclusion criteria regarding underlying co-pathologies were screened. In cases of concomitant surgeries, the type of surgeries and their specific indications were extracted.

RESULTS

A total of 35 original articles were included out of which 27 (77%) were cohort studies with level IV evidence. The most frequently used technique for cartilage restoration of the patella was autologous chondrocyte implantation (ACI). Results after isolated cartilage repair alone were reported by 15 (43%) studies. Of those studies, 9 (60%) excluded patients with underlying patellofemoral malalignment a priori and 6 (40%) did not analyse underlying co-pathologies at all. Among the studies including combined surgeries, the most frequently reported concomitant procedures were release of the lateral retinaculum, reconstruction of the medial patellofemoral ligament (MPFL), and osteotomy of the tibial tubercle. In summary, these studies showed lower preoperative PROMS but similar final PROMS in comparison with the studies reporting on isolated cartilage repair. The most frequently used PROMS were the IKDC-, Lysholm- and the Modified Cincinnati Score.

CONCLUSION

This comprehensive literature review demonstrated good clinical outcomes after patellar cartilage repair with no evidence of minor results even in complex cases with the need for additional patellofemoral realignment procedures. However, a meaningful statistical comparison between isolated patellar cartilage repair and combined co-procedures is not possible due to very heterogeneous patient cohorts and a lack of analysis of specific subgroups in recent literature.

LEVEL OF EVIDENCE

Level IV.

Osteochondritis Dissecans: Current Understanding of Epidemiology, Etiology, Management, and Outcomes

➤

Osteochondritis dissecans occurs most frequently in the active pediatric and young adult populations, commonly affecting the knee, elbow, or ankle, and may lead to premature osteoarthritis.

➤

While generally considered an idiopathic phenomenon, various etiopathogenetic theories are being investigated, including local ischemia, aberrant endochondral ossification of the secondary subarticular physis, repetitive microtrauma, and genetic predisposition.

➤

Diagnosis is based on the history, physical examination, radiography, and advanced imaging, with elbow ultrasonography and novel magnetic resonance imaging protocols potentially enabling early detection and in-depth staging.

➤

Treatment largely depends on skeletal maturity and lesion stability, defined by the presence or absence of articular cartilage fracture and subchondral bone separation, as determined by imaging and arthroscopy, and is typically nonoperative for stable lesions in skeletally immature patients and operative for those who have had failure of conservative management or have unstable lesions.

➤

Clinical practice guidelines have been limited by a paucity of high-level evidence, but a multicenter effort is ongoing to develop accurate and reliable classification systems and multimodal decision-making algorithms with prognostic value.

Treatment of osteochondritis dissecans of the patella in adolescents with nanofractured autologous matrix-induced chondrogenesis (NAMIC): A report of five cases

PURPOSE

Osteochondritis dissecans (OCD) of the patella is a very rare affliction. The aim of this case series is to evaluate the effectiveness of the Nanofractured Autologous Matrix-Induced Chondrogenesis (NAMIC) technique for the treatment of OCD in young adults.

METHODS

Five consecutive patients with patellar osteochondral lesions treated with NAMIC were prospectively studied. There were 4 males and 1 female with a mean age of 15.2 years, ranging from 12 to 18 years. Clinically, they presented pain when going up and down stairs or squatting, effusion, swelling and functional limitation. The International Cartilage Repair Society (ICRS) grade was III in 4 patients and IV in 1 patient. Patients were functionally evaluated with the Lysholm knee score, the Tegner Activity Score (TAS) and the Knee Injury and Osteoarthritis Outcome Score (KOOS) and radiologically using the Magnetic resonance Observation of Cartilage Repair Tissue (MOCART) score.

RESULTS

All the scores significantly improved two years after surgery with respect to pre-operative values (Lysholm score from 63.8 ± 3.9 before surgery to 91 ± 3.2 at 2 years; Tegner activity score from 3.6 ± 0.5 to 8.2 ± 0.8 and the KOOS score from 45.2 ± 2.6 to 91.2 ± 2.4). Both the X-rays and the Magnetic Resonance Imaging (MRI) showed good joint regularity with an average MOCART of 80 ± 7.1/100.

CONCLUSIONS

Treatment of juvenile patellar osteochondritis dissecans with the NAMIC technique seems to be a reliable technique in the short term to restore the patella joint surface and obtain good functional results.

Bilateral osteochondral defects of the patellae in an 11-year-old girl

Osteochondral defect or osteochondritis dissecans (OCD) of the knee usually affects young, active populations. It is a challenging diagnosis as patients typically present with poorly localised activity-related pain, which is non-specific and covers many differentials. We present an active 11-year-old girl with bilateral osteochondral defects of the patellae: a rare clinical disorder which was affecting her sporting activities. She had a 12-month history of bilateral anterior knee pain before the diagnosis was achieved with appropriate imaging. Her pain significantly improved with activity modification and physiotherapy. Follow-up will require outpatient clinic assessment and imaging to determine if non-operative management continues to be successful or surgery may be required. This case report emphasises the importance of appropriate high index of suspicion when managing patients with non-specific knee pain. It also demonstrates the importance of judicious use of imaging to avoid a missed or delayed diagnosis.

Quantitative assessment of the vascularity of the skeletally immature patella: a cadaveric study using MRI

PURPOSE

While predominant blood supply to the adult patella enters inferomedially, little is known about skeletally immature patellar perfusion. Improved knowledge of immature patella vascularity can further understanding of osteochondritis dissecans, dorsal defects of the patella and bipartite patella, and help ensure safe surgical approaches. We hypothesized that the immature patella would exhibit more uniform blood flow. The study purpose was to quantify immature patella regional perfusion in comparison with adults.

METHODS

Ten cadaveric knees were utilized (five immature, five mature). The superficial femoral artery was cannulated proximally. Signal enhancement increases were compared from pre- to post-contrast MRI to assess relative arterial contributions to patella regions (quadrants, anterior/posterior, superior/inferior, medial/lateral, and outer/inner).

RESULTS

Quantitative-MRI analysis revealed similar distribution of enhancement between the immature and mature patella. The inferior pole exhibited significantly higher arterial contribution versus superior pole in both immature and mature groups (p = 0.009; both groups), while the inferomedial quadrant had the highest arterial contribution of all quadrants in both groups. The superolateral quadrant demonstrated the lowest arterial contribution in the immature group and second lowest in the adult group. The patella outer periphery had significantly greater arterial contribution than the inner central region in both immature (p = 0.009) and mature (p = 0.009) groups.

CONCLUSION

Distribution of arterial contributions between the immature and mature patella was similar. Our results highlight the importance of inferior and inferomedial blood supply in both immature and mature patellas. These findings have implications for paediatric and adult patients; surgical damage to inferior patellar vessels should be avoided to prevent associated complications.

Bone marrow aspirate concentration provided better results in cartilage regeneration to microfracture in knee of osteoarthritic patients

PURPOSE

To determine whether microfracture with bone marrow aspirate concentrate (BMAC) improves functional outcome and cartilage regeneration better than microfracture alone in patients undergoing high tibial osteotomy (HTO) for medial unicompartmental osteoarthritis (OA).

METHODS

Among 436 patients treated with HTO for medial unicompartmental OA with varus deformity between 2010 and 2016, clinical outcomes were retrospectively compared between the microfracture alone group (group I, 43 cases) and microfracture with BMAC augmentation group (group II, 48 cases). Of these, 64 patients underwent a second-look arthroscopic assessment. Clinical outcomes were compared based on the Knee Society Score (KSS), International Knee Documentation Committee (IKDC) subjective score, and Western Ontario and McMaster Universities Arthritis Index (WOMAC). Cartilage regeneration was assessed according to Koshino's staging system and the International Cartilage Repair Society (ICRS) Cartilage Repair Assessment (CRA) grading system.

RESULTS

At the last follow-up, there were no significant intergroup differences in terms of KSS for pain and function (p > 0.05). Moreover, WOMAC scores were similar between the two groups (p > 0.05). Regarding second-look arthroscopy findings, according to Koshino's staging system, there was no significant intergroup difference in terms of defect coverage (p = 0.187). However, group II showed a significantly better mean CRA score than group I (p = 0.035).

CONCLUSION

There were no significant differences in clinical outcomes and cartilage regeneration between the groups. However, the CRA score was significantly higher with BMAC augmentation and microfracture than microfracture alone. Therefore, BMAC augmentation had a synergistic effect for a better cartilage regeneration, although studies with a longer follow-up might help to confirm whether microfracture with BMAC augmentation would ensure better clinical outcomes than microfracture alone for the treatment of knee OA.

Patellofemoral Cartilage Restoration: A Systematic Review and Meta-analysis of Clinical Outcomes

BACKGROUND

Many surgical options for treating patellofemoral (PF) cartilage lesions are available but with limited evidence comparing their results.

PURPOSE

To determine and compare outcomes of PF cartilage restoration techniques.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

PRISMA (Preferred Reporting Items for Systematic Meta-Analyses) guidelines were followed by utilizing the PubMed, EMBASE, and Cochrane Library databases. Inclusion criteria were clinical studies in the English language, patient-reported outcomes after PF cartilage restoration surgery, and >12 months' follow-up. Quality assessment was performed with the Coleman Methodology Score. Techniques were grouped as osteochondral allograft transplantation (OCA), osteochondral autograft transfer (OAT), chondrocyte cell-based therapy, bone marrow-based therapy, and scaffolds.

RESULTS

A total of 59 articles were included. The mean Coleman Methodology Score was 71.8. There were 1937 lesions (1077 patellar, 390 trochlear, and 172 bipolar; 298 unspecified). The frequency of the procedures was as follows, in descending order: chondrocyte cell-based therapy (65.7%), bone marrow-based therapy (17.2%), OAT (8%), OCA (6.6%), and scaffolds (2.2%). When compared with the overall pooled lesion size (3.9 cm²; 95% CI, 3.5-4.3 cm²), scaffold (2.2 cm²; 95% CI, 1.8-2.5 cm²) and OAT (1.5 cm²; 95% CI, 1.1-1.9 cm²) lesions were smaller (P < .001), while chondrocyte cell-based therapy lesions were larger (4.7 cm²; 95% CI, 4.1-5.3 cm²; P = .039). Overall, the instability pool was 11.9%, and the anatomic risk factors pool was 32.1%. Statistically significant improvement was observed on at least 1 patient-reported outcome in chondrocyte cell-based therapy (83%), OAT (78%), OCA (71%), bone marrow-based therapy (64%), and scaffolds (50%). There were no significant differences between any group and the overall pooled change in International Knee Documentation Committee score (30.2; 95% CI, 27.4-32.9) and Lysholm score (25.2; 95% CI, 16.9-33.5). There were no significant differences between any group and the overall pooled rate in minor complication rate (7.6%; 95% CI, 4.7%-11.9%) and major complication rate (8.3%; 95% CI, 5.7%-12.0%); however, OCA had a significantly greater failure rate (22.7%; 95% CI, 14.6%-33.4%) as compared with the overall rate (6.8%; 95% CI, 4.7%-9.5%).

CONCLUSION

PF cartilage restoration leads to improved clinical outcomes, with low rates of minor and major complications. There was no difference among techniques; however, failures were higher with OCA.

Clinical outcome after mosaicplasty of knee articular cartilage defects of patellofemoral joint versus tibiofemoral joint

Background

The purpose was to investigate survival of cartilage repair in the knee joint by osteochondral autograft transfer stratified by location of the lesion; patellofemoral joint (N = 26) versus the medial or lateral femoral condyles (N = 58).

Methods

For survival analyses, “failure” was defined as the event of a patient reporting a poor Lysholm score (below 65 points) or undergoing a knee replacement procedure.

Results

The survival distribution was not significantly different between the patellofemoral joint and the tibiofemoral joint groups.

Conclusions

The current study suggest that similar long-term outcome can be expected after OAT procedures for the patellofemoral or tibiofemoral joint.

Level of evidence

Therapeutic study, Level III.

Clinical observation of C3-type patellar fractures treated by operation methods with or without a turned-over patella

OBJECTIVE

To evaluate the clinical efficacy of operation methods with or without a turned-over patella for treatment of C3-type patellar fractures.

METHODS

A total of 68 patients with C3-type patellar fractures undergoing open reduction and internal fixation were retrospectively selected and treated with a turned-over patella surgery (turned-over patella group, n = 30) or conventional therapy without turning over the patella (conventional group, n = 38). The intraoperative and postoperative indicators of the two groups were assessed and comparatively analyzed.

RESULTS

The bedridden time was significantly shorter in the turned-over patella group than in the conventional group (P = 0.002), while the range of motion (ROM) of knee joint was significantly higher in the turned-over patella group (P = 0.044). The Lysholm score was slightly higher in the turned-over patella group than in the conventional group, but the difference was not statistically significant (P = 0.055). No significant difference was observed between the two groups in terms of the operation time (P = 0.096), intraoperative blood loss (P = 0.543), time of weight bearing (P = 0.312), fracture healing time (P = 0.272), or complications (P = 1).

CONCLUSION

The turned-over patella operation method exhibited some superiority to conventional reduction-fixation approach for treatment of C3-type patellar fractures in terms of efficacy and safety by enlarging the ROM of the knee joint and promoting functional recovery.

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.