A retrospective analysis of two independent prospective cartilage repair studies: autogenous perichondrial grafting versus subchondral drilling 10 years post-surgery

Treatment of knee cartilage lesions in 2024: From hyaluronic acid to regenerative medicine

Abstract

Intact articular cartilage plays a vital role in joint homeostasis. Local cartilage repairs, where defects in the cartilage matrix are filled in and sealed to congruity, are therefore important treatments to restore a joint equilibrium. The base for all cartilage repairs is the cells; either chondrocytes or chondrogeneic cells from bone, synovia and fat tissue. The surgical options include bone marrow stimulation techniques alone or augmented with scaffolds, chondrogeneic cell implantations and osteochondral auto- or allografts. The current trend is to choose one-stage procedures being easier to use from a regulatory point of view. This narrative review provides an overview of the current nonoperative and surgical options available for the repair of various cartilage lesions.

Level of Evidence

Level IV.

Strategies to Convert Cells into Hyaline Cartilage: Magic Spells for Adult Stem Cells

Damaged hyaline cartilage gradually decreases joint function and growing pain significantly reduces the quality of a patient’s life. The clinically approved procedure of autologous chondrocyte implantation (ACI) for treating knee cartilage lesions has several limits, including the absence of healthy articular cartilage tissues for cell isolation and difficulties related to the chondrocyte expansion in vitro. Today, various ACI modifications are being developed using autologous chondrocytes from alternative sources, such as the auricles, nose and ribs. Adult stem cells from different tissues are also of great interest due to their less traumatic material extraction and their innate abilities of active proliferation and chondrogenic differentiation. According to the different adult stem cell types and their origin, various strategies have been proposed for stem cell expansion and initiation of their chondrogenic differentiation. The current review presents the diversity in developing applied techniques based on autologous adult stem cell differentiation to hyaline cartilage tissue and targeted to articular cartilage damage therapy.

Mesenchymal Stem Cell Studies in the Goat Model for Biomedical Research—A Review of the Scientific Literature

Simple Summary

This review article aims to compile the works published in the scientific literature, over the last two decades, that use the goat as an animal model in preclinical studies using stem cells, alone or associated with biomaterials, for the treatment of injury or disease in divers organ systems. These preclinical studies are performed prior to human clinical trials for the implementation of new medical or surgical therapies in clinical practice. Thus, it appears that, in the area of tissue engineering and regenerative medicine, the caprine model is particularly used in studies using stem cells in the musculoskeletal system but, although in a more limited way, also in the field of dermatology, ophthalmology, dentistry, pneumology, cardiology, and urology. It appears that the goat represents a particularly useful animal model for studies related to the locomotor system because of its size, and also because they have a more active behavior than sheep, being more similar to the human species in this aspect. Additionally, the goat knee anatomy and the thickness of the cartilage that covers this joint are closer to that of humans than that of other large animal models commonly used in orthopedic research.

Abstract

Mesenchymal stem cells (MSCs) are multipotent cells, defined by their ability to self-renew, while maintaining the capacity to differentiate into different cellular lineages, presumably from their own germinal layer. MSCs therapy is based on its anti-inflammatory, immunomodulatory, and regenerative potential. Firstly, they can differentiate into the target cell type, allowing them to regenerate the damaged area. Secondly, they have a great immunomodulatory capacity through paracrine effects (by secreting several cytokines and growth factors to adjacent cells) and by cell-to-cell contact, leading to vascularization, cellular proliferation in wounded tissues, and reducing inflammation. Currently, MSCs are being widely investigated for numerous tissue engineering and regenerative medicine applications. Appropriate animal models are crucial for the development and evaluation of regenerative medicine-based treatments and eventual treatments for debilitating diseases with the hope of application in upcoming human clinical trials. Here, we summarize the latest research focused on studying the biological and therapeutic potential of MSCs in the goat model, namely in the fields of orthopedics, dermatology, ophthalmology, dentistry, pneumology, cardiology, and urology fields.

Subchondral Drilling Independent of Drill Hole Number Improves Articular Cartilage Repair and Reduces Subchondral Bone Alterations Compared With Debridement in Adult Sheep

BACKGROUND

Subchondral drilling is an established marrow stimulation technique for small cartilage defects, but whether drilling is required at all and if the drill hole density affects repair remains unclear.

HYPOTHESES

Osteochondral repair is improved when the subchondral bone is perforated by a higher number of drill holes per unit area, and drilling is superior to defect debridement alone.

STUDY DESIGN

Controlled laboratory study.

METHODS

Rectangular full-thickness chondral defects (4 × 8 mm) were created in the trochlea of adult sheep (N = 16), debrided down to the subchondral bone plate without further treatment as controls (no treatment; n = 7) or treated with either 2 or 6 (n = 7 each) subchondral drill holes (diameter, 1.0 mm; depth, 10.0 mm). Osteochondral repair was assessed at 6 months postoperatively by standardized (semi-)quantitative macroscopic, histological, immunohistochemical, biochemical, and micro-computed tomography analyses.

RESULTS

Compared with defect debridement alone, histological overall cartilaginous repair tissue quality (P = .025) and the macroscopic aspect of the adjacent cartilage (P≤ .032) were improved after both drilling densities. Only drilling with 6 holes increased type 2 collagen content in the repair tissue compared with controls (P = .038). After debridement, bone mineral density was significantly decreased in the subchondral bone plate (P≤ .015) and the subarticular spongiosa (P≤ .041) compared with both drilling groups. Debridement also significantly increased intralesional osteophyte sectional area compared with drilling (P≤ .034). No other differences in osteochondral repair existed between subchondral drilling with 6 or 2 drill holes.

CONCLUSION

Subchondral drilling independent of drill hole density significantly improves structural cartilage repair compared with sole defect debridement of full-thickness cartilage defects in sheep after 6 months. Subchondral drilling also leads to a better reconstitution of the subchondral bone compartment below the defects. Simultaneously, drilling reduced the formation of intralesional osteophytes caused by osseous overgrowth compared with debridement.

CLINICAL RELEVANCE

These results have important clinical implications, as they support subchondral drilling independent of drill hole number but discourage debridement alone for the treatment of small cartilage defects. Clinical studies are warranted to further quantify the effects of subchondral drilling in similar settings.

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.

Twenty-Two-Year Outcome of Cartilage Repair Surgery by Perichondrium Transplantation

OBJECTIVE

The main purpose of the present study was to assess the risk for major revision surgery after perichondrium transplantation (PT) at a minimum of 22 years postoperatively and to evaluate the influence of patient characteristics.

DESIGN

Primary outcome was treatment success or failure. Failure of PT was defined as revision surgery in which the transplant was removed, such as (unicondylar) knee arthroplasty or patellectomy. The functioning of nonfailed patients was evaluated using the International Knee Documentation Committee (IKDC) score. In addition, the influence of patient characteristics was evaluated.

RESULTS

Ninety knees in 88 patients, aged 16 to 55 years with symptomatic cartilage defects, were treated by PT. Eighty knees in 78 patients were eligible for analysis and 10 patients were lost to follow-up. Twenty-eight knees in 26 patients had undergone major revision surgery. Previous surgery and a longer time of symptoms prior to PT were significantly associated with an increased risk for failure of cartilage repair. Functioning of the remaining 52 patients and influence of patient characteristics was analyzed using their IKDC score. Their median IKDC score was 39.08, but a relatively young age at transplantation was associated with a higher IKDC score.

CONCLUSIONS

This 22-year follow-up study of PT, with objective outcome parameters next to patient-reported outcome measurements in a unique group of patients, shows that overall 66% was without major revision surgery and patient characteristics also influence long-term outcome of cartilage repair surgery.

7-Tesla MRI Evaluation of the Knee, 25 Years after Cartilage Repair Surgery: The Influence of Intralesional Osteophytes on Biochemical Quality of Cartilage

OBJECTIVE

To evaluate the morphological and biochemical quality of cartilage transplants and surrounding articular cartilage of patients 25 years after perichondrium transplantation (PT) and autologous chondrocyte transplantation (ACT) as measured by ultra-high-field 7-Tesla (7T) magnetic resonance imaging (MRI) and to present these findings next to clinical outcome.

DESIGN

Seven PT patients and 5 ACT patients who underwent surgery on the femoral condyle between 1986 and 1996 were included. Patient-reported outcome measures (PROMs) were assessed by the clinical questionnaires: Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC), and Visual Analogue Scale (VAS) for knee pain. The morphological (MOCART score) and biochemical quality (glycosaminoglycans [GAGs] content and collagen integrity) of cartilage transplants and surrounding articular cartilage were analyzed by 7T MRI. The results of the PT and ACT patients were compared. Finally, a detailed morphological analysis of the grafts alone was performed.

RESULTS

No statistically significant difference was found for the PROMs and MOCART scores of PT and ACT patients. Evaluation of the graft alone showed poor repair tissue quality and high prevalence of intralesional osteophyte formation in both the PT and ACT patients. Penetration of the graft surface by the intralesional osteophyte was related to biochemically damaged opposing tibial cartilage; GAG content was significantly lower in patients with an osteophyte penetrating the graft surface.

CONCLUSIONS

Both PT and ACT patients have a high incidence of intralesional osteophyte formation 25 years after surgery. The resulting biochemical damage to the opposing tibial cartilage might be dependent on osteophyte morphology.

Rat perichondrium transplanted to articular cartilage defects forms articular-like, hyaline cartilage

OBJECTIVE

Perichondrium autotransplants have been used to reconstruct articular surfaces destroyed by infection or trauma. However, the role of the transplanted perichondrium in the healing of resurfaced joints has not been investigated.

DESIGN

Perichondrial and periosteal tissues were harvested from rats hemizygous for a ubiquitously expressed enhanced green fluorescent protein (EGFP) transgene and transplanted into full-thickness articular cartilage defects at the trochlear groove of distal femur in wild-type littermates. As an additional control, cartilage defects were left without a transplant (no transplant control). Distal femurs were collected 3, 14, 56, 112 days after surgery.

RESULTS

Tracing of transplanted cells showed that both perichondrium and periosteum transplant-derived cells made up the large majority of the cells in the regenerated joint surfaces. Perichondrium transplants contained SOX9 positive cells and with time differentiated into a hyaline cartilage that expanded and filled out the defects with Col2a1-positive and Col1a1-negative chondrocytes and a matrix rich in proteoglycans. At later timepoints the cartilaginous perichondrium transplants were actively remodeled into bone at the transplant-bone interface and at post-surgery day 112 EGFP-positive perichondrium cells at the articular surface were positive for Prg4. Periosteum transplants initially lacked SOX9 expression and despite a transient increase in SOX9 expression and chondrogenic differentiation, remained Col1a1 positive, and were continuously thinning as periosteum-derived cells were incorporated into the subchondral compartment.

CONCLUSIONS

Perichondrium and periosteum transplanted to articular cartilage defects did not just stimulate regeneration but were themselves transformed into cartilaginous articular surfaces. Perichondrium transplants developed into an articular-like, hyaline cartilage, whereas periosteum transplants appeared to produce a less resilient fibro-cartilage.

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.

Two-component surface replacement implants compared with perichondrium transplantation for restoration of Metacarpophalangeal and proximal Interphalangeal joints: a retrospective cohort study with a mean follow-up time of 6 respectively 26 years

Background

The aim of our study was to compare the long-term outcome after perichondrium transplantation and two-component surface replacement (SR) implants to the metacarpophalangeal (MCP) and the proximal interphalangeal (PIP) joints.

Methods

We evaluated 163 joints in 124 patients, divided into 138 SR implants in 102 patients and 25 perichondrium transplantations in 22 patients. Our primary outcome was any revision surgery of the index joint.

Results

The median follow-up time was 6 years (0–21) for the SR implants and 26 years (1–37) for the perichondrium transplants. Median age at index surgery was 64 years (24–82) for SR implants and 45 years (18–61) for perichondium transplants. MCP joint survival was slightly better in the perichondrium group (86.7%; 95% confidence interval [CI]: 69.4–100.0) than in the SR implant group (75%; CI 53.8–96.1), but not statistically significantly so (p = 0.4). PIP joint survival was also slightly better in the perichondrium group (80%; CI 55–100) than in the SR implant group (74.7%; CI 66.6–82.7), but below the threshold of statistical significance (p = 0.8).

Conclusion

In conclusion, resurfacing of finger joints using transplanted perichondrium is a technique worth considering since the method has low revision rates in the medium term and compares favorable to SR implants.

Level of evidence

III (Therapeutic).

Exquisite design of injectable Hydrogels in Cartilage Repair

Cartilage damage is still a threat to human beings, yet there is currently no treatment available to fully restore the function of cartilage. Recently, due to their unique structures and properties, injectable hydrogels have been widely studied and have exhibited high potential for applications in therapeutic areas, especially in cartilage repair. In this review, we briefly introduce the properties of cartilage, some articular cartilage injuries, and now available treatment strategies. Afterwards, we propose the functional and fundamental requirements of injectable hydrogels in cartilage tissue engineering, as well as the main advantages of injectable hydrogels as a therapy for cartilage damage, including strong plasticity and excellent biocompatibility. Moreover, we comprehensively summarize the polymers, cells, and bioactive molecules regularly used in the fabrication of injectable hydrogels, with two kinds of gelation, i.e., physical and chemical crosslinking, which ensure the excellent design of injectable hydrogels for cartilage repair. We also include novel hybrid injectable hydrogels combined with nanoparticles. Finally, we conclude with the advances of this clinical application and the challenges of injectable hydrogels used in cartilage repair.

Animal Models of Osteochondral Defect for Testing Biomaterials

The treatment of osteochondral defects (OCD) remains a great challenge in orthopaedics. Tissue engineering holds a good promise for regeneration of OCD. In the light of tissue engineering, it is critical to establish an appropriate animal model to evaluate the degradability, biocompatibility, and interaction of implanted biomaterials with host bone/cartilage tissues for OCD repair in vivo. Currently, model animals that are commonly deployed to create osteochondral lesions range from rats, rabbits, dogs, pigs, goats, and sheep horses to nonhuman primates. It is essential to understand the advantages and disadvantages of each animal model in terms of the accuracy and effectiveness of the experiment. Therefore, this review aims to introduce the common animal models of OCD for testing biomaterials and to discuss their applications in translational research. In addition, we have reviewed surgical protocols for establishing OCD models and biomaterials that promote osteochondral regeneration. For small animals, the non-load-bearing region such as the groove of femoral condyle is commonly chosen for testing degradation, biocompatibility, and interaction of implanted biomaterials with host tissues. For large animals, closer to clinical application, the load-bearing region (medial femoral condyle) is chosen for testing the durability and healing outcome of biomaterials. This review provides an important reference for selecting a suitable animal model for the development of new strategies for osteochondral regeneration.

In Situ Articular Cartilage Regeneration through Endogenous Reparative Cell Homing Using a Functional Bone Marrow-Specific Scaffolding System

In situ tissue regeneration by homing endogenous reparative cells to the injury site has been extensively researched as a promising alternative strategy to facilitate tissue repair. In this study, a promising scaffolding system DCM-RAD/SKP, which integrated a decellularized cartilage matrix (DCM)-derived scaffold with a functionalized self-assembly Ac-(RADA)₄-CONH₂/Ac-(RADA)₄GGSKPPGTSS-CONH₂ (RAD/SKP) peptide nanofiber hydrogel, was designed for repairing rabbit osteochondral defect. In vitro experiments showed that rabbit bone marrow stem cells migrated into and have higher affinity toward the functional scaffolding system DCM-RAD/SKP than the control scaffolds. One week after in vivo implantation, the functional scaffolding system DCM-RAD/SKP facilitated the recruitment of endogenous mesenchymal stem cells within the defect site. Moreover, gene expression analysis indicated that the DCM-RAD/SKP promoted chondrogenesis of the recruited cells. In vivo results showed that the DCM-RAD/SKP achieved superior hyaline-like cartilage repair and successful subchondral bone reconstruction. By contrast, the control groups mostly led to fibrous tissue repair. These findings indicate that the DCM-RAD/SKP can recruit endogenous stem cells into the site of cartilage injury and promote differentiation of the infiltrating cells into the chondrogenic lineage, holding great potential as a one-step surgery strategy for cartilage repair.

Effects of collagen matrix and bioreactor cultivation on cartilage regeneration of a full-thickness critical-size knee joint cartilage defects with subchondral bone damage in a rabbit model

Cartilage has limited self-repair ability. The purpose of this study was to investigate the effects of different species of collagen-engineered neocartilage for the treatment of critical-size defects in the articular joint in a rabbit model. Type II and I collagen obtained from rabbits and rats was mixed to form a scaffold. The type II/I collagen scaffold was then mixed with rabbit chondrocytes to biofabricate neocartilage constructs using a rotating cell culture system [three-dimensional (3D)-bioreactor]. The rabbit chondrocytes were mixed with rabbit collagen scaffold and rat collagen scaffold to form neoRBT (neo-rabbit cartilage) and neoRAT (neo-rat cartilage) constructs, respectively. The neocartilage matrix constructs were implanted into surgically created defects in rabbit knee chondyles, and histological examinations were performed after 2 and 3 months. Cartilage-like lacunae formation surrounding the chondrocytes was noted in the cell cultures. After 3 months, both the neoRBT and neoRAT groups showed cartilage-like repair tissue covering the 5-mm circular, 4-mm-deep defects that were created in the rabbit condyle and filled with neocartilage plugs. Reparative chondrocytes were aligned as apparent clusters in both the neoRAT and neoRBT groups. Both neoRBT and neoRAT cartilage repair demonstrated integration with healthy adjacent tissue; however, more integration was obtained using the neoRAT cartilage. Our data indicate that different species of type II/I collagen matrix and 3D bioreactor cultivation can facilitate cartilage engineering in vitro for the repair of critical-size defect.

Large Animal Models for Osteochondral Regeneration

Namely, in the last two decades, large animal models - small ruminants (sheep and goats), pigs, dogs and horses - have been used to study the physiopathology and to develop new therapeutic procedures to treat human clinical osteoarthritis. For that purpose, cartilage and/or osteochondral defects are generally performed in the stifle joint of selected large animal models at the condylar and trochlear femoral areas where spontaneous regeneration should be excluded. Experimental animal care and protection legislation and guideline documents of the US Food and Drug Administration, the American Society for Testing and Materials and the International Cartilage Repair Society should be followed, and also the specificities of the animal species used for these studies must be taken into account, such as the cartilage thickness of the selected defect localization, the defined cartilage critical size defect and the joint anatomy in view of the post-operative techniques to be performed to evaluate the chondral/osteochondral repair. In particular, in the articular cartilage regeneration and repair studies with animal models, the subchondral bone plate should always be taken into consideration. Pilot studies for chondral and osteochondral bone tissue engineering could apply short observational periods for evaluation of the cartilage regeneration up to 12 weeks post-operatively, but generally a 6- to 12-month follow-up period is used for these types of studies.

BMP-2 gene activated muscle tissue fragments for osteochondral defect regeneration in the rabbit knee

BACKGROUND

Previously published data indicate that BMP-2 gene activated muscle tissue grafts can repair large bone defects in rats. This innovative abbreviated ex vivo gene therapy is appealing because it does not require elaborative and time-consuming extraction and expansion of cells. Hence, in the present study, we evaluated the potential of this expedited tissue engineering approach for regenerating osteochondral defects in rabbits.

METHODS

Autologous muscle tissue grafts from female White New Zealand rabbits were directly transduced with an adenoviral BMP-2 vector or remained unmodified. Osteochondral defects in the medial condyle of rabbit knees were treated with either BMP-2 activated muscle tissue implants or unmodified muscle tissue or remained empty. After 13 weeks, repair of osteochondral defects was examined by biomechanical indentation testing and by histology/imunohistochemistry applying an extended O'Driscoll scoring system and histomorphometry.

RESULTS

Biomechanical investigations revealed a trend towards slightly improved mechanical properties of the group receiving BMP-2 activated muscle tissue compared to unmodified muscle treatment and empty defect controls. However, a statistically significant difference was noted only between BMP-2 muscle and unmodified muscle treatment. Also, histological evaluation resulted in slightly higher histological scores and improved collagen I/II ratio without statistical significance in the BMP-2 treatment group. Histomorphometry indicated enhanced repair of subchondral bone after treatment with BMP-2 muscle, with a significantly larger bone area compared to untreated defects.

CONCLUSIONS

Gene activated muscle tissue grafts showed potential for osteochondral defect repair. There is room for improvement via the use of appropriate growth factor combinations.

Autologous nasal chondrocytes delivered by injectable hydrogel for in vivo articular cartilage regeneration

Cell based tissue engineering serves as a promising strategy for articular cartilage repair, which remains a challenge both for researchers and clinicians. The aim of this research was to assess the potential of autologous nasal chondrocytes (NCs) combined with alginate hydrogel as injectable constructs for rabbit articular cartilage repair. Autologous nasal chondrocytes were isolated from rabbit nasal septum, expanded either on monolayer or in 3D alginate hydrogel. In vitro, DNA quantification revealed that NCs can proliferate stable in 3D alginate matrix, but slower than that cultured in monolayer. Further, a higher synthesis rate of glycosaminoglycans (GAGs) was detected by GAG measurement in 3D alginate culture. Gene expression analysis at different time point (day 1, 7, 14) showed that 3D culture of NCs in alginate up-regulated chondrogenic markers (Col2A1, ACAN SOX9), meanwhile down-regulated dedifferentiation related gene (Col1A1). In vivo, autologous nasal chondrocytes combined with alginate hydrogel were used for repairing rabbit knee osteochondral defect (Alg + NC group). Histological staining indicated that Alg + NC group obtained superior and more hyaline-like repaired tissue both at 3 and 6 months after surgery. Mechanical analysis showed that the repaired tissue in the Alg + NC group possessed similar mechanical properties to the native cartilage. In conclusion, nasal chondrocytes appeared to be a very promising seed cell source for cartilage tissue engineering, and alginate hydrogel can serve as suitable delivery system.

The CS Sulfation Motifs 4C3, 7D4, 3B3[-]; and Perlecan Identify Stem Cell Populations and Their Niches, Activated Progenitor Cells and Transitional Areas of Tissue Development in the Fetal Human Elbow

We compared the immunohistochemical distribution of (1) the novel chondroitin sulfate (CS) sulfation motifs 7D4, 4C3, and 3B3[-], (2) native heparan sulfate (HS) and Δ-HS "stubs" generated by heparitinase III digestion and (3) the HS-proteoglycan (PG), perlecan, in the fetal human elbow joint. Putative stem cell populations associated with hair bulbs, humeral perichondrium, humeral and ulnar rudiment stromal/perivascular tissues expressed the CS motifs 4C3, 7D4, and 3B3[-] along with perlecan in close association but not colocalized. Chondrocytes in the presumptive articular cartilage of the fetal elbow expressed the 4C3 and 7D4 CS sulfation motifs consistent with earlier studies on the expression of these motifs in knee cartilage following joint cavitation. This study also indicated that hair bulbs, skin, perichondrium, and rudiment stroma were all perlecan-rich progenitor cell niches that contributed to the organization and development of the human fetal elbow joint and associated connective tissues. One of the difficulties in determining the precise role of stem cells in tissue development and repair processes is their short engraftment period and the lack of specific markers, which differentiate the activated stem cell lineages from the resident cells. The CS sulfation motifs 7D4, 4C3, and 3B3[-] decorate cell surface PGs on activated stem/progenitor cells and thus can be used to identify these cells in transitional areas of tissue development and in repair tissues and may be applicable to determining a more precise mode of action of stem cells in these processes. Isolation of perlecan from 12 to 14 week gestational age fetal knee rudiments demonstrated that perlecan in these fetal tissues was a HS-CS hybrid PG further supporting roles for CS in tissue development.

Tissue-engineering strategies to repair chondral and osteochondral tissue in osteoarthritis: use of mesenchymal stem cells

Focal chondral or osteochondral lesions can be painful and disabling because they have insufficient intrinsic repair potential, and constitute one of the major extrinsic risk factors for osteoarthritis (OA). Attention has, therefore, been paid to regenerative therapeutic procedures for the early treatment of cartilaginous defects. Current treatments for OA are not regenerative and have little effect on the progressive degeneration of joint tissue. One major reason for this underrepresentation of regenerative therapy is that approaches to treating OA with cell-based strategies have to take into consideration the larger sizes of the defects, as compared with isolated focal articular-cartilage defects, and the underlying disease process. Here, we review current treatment strategies using mesenchymal stem cells (MSCs) for chondral and osteochondral tissue repair in trauma and OA-affected joints. We discuss tissue-engineering approaches, in preclinical large-animal models and clinical studies in humans, which use crude bone-marrow aspirates and MSCs from different tissue sources in combination with bioactive agents and materials.

Origin and function of cartilage stem/progenitor cells in osteoarthritis

Articular cartilage is a physiologically non-self-renewing avascular tissue with a singular cell type, the chondrocyte, which functions as the load-bearing surface of the arthrodial joint. Injury to cartilage often progresses spatiotemporally from the articular surface to the subchondral bone, leading to development of degenerative joint diseases such as osteoarthritis (OA). Although lacking intrinsic reparative ability, articular cartilage has been shown to contain a population of stem cells or progenitor cells, similar to those found in many other adult tissues, that are thought to be involved in the maintenance of tissue homeostasis. These so-called cartilage-derived stem/progenitor cells (CSPCs) have been observed in human, equine and bovine articular cartilage, and have been identified, isolated and characterized on the basis of expression of stem-cell-related surface markers, clonogenicity and multilineage differentiation ability. However, the origin and functions of CSPCs are incompletely understood. We review here the current status of CSPC research and discuss the possible origin of these cells, what role they might have in cartilage repair, and their therapeutic potential in OA.

Osteotomy for treating knee osteoarthritis

BACKGROUND

Patients with unicompartmental osteoarthritis of the knee can be treated with an osteotomy. The goal of an osteotomy is to unload the diseased compartment of the knee. This is the second update of the original review published in The Cochrane Library, Issue 1, 2005.

OBJECTIVES

To assess the benefits and harms of an osteotomy for treating patients with knee osteoarthritis, including the following main outcomes scores: treatment failure, pain and function scores, health-related quality of life, serious adverse events, mortality and reoperation rate.

SEARCH METHODS

The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE (Current Contents, HealthSTAR) were searched until November 2013 for this second update.

SELECTION CRITERIA

Randomised and controlled clinical trials comparing an osteotomy with other treatments for patients with unicompartmental osteoarthritis of the knee.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, extracted data and assessed risk of bias using the domains recommended in the 'Risk of bias' tool of The Cochrane Collaboration. The quality of the results was analysed by performing overall grading of evidence by outcome using the GRADE (Grades of Recommendation, Assessment, Development and Evaluation) approach.

MAIN RESULTS

Eight new studies were included in this update, for a total of 21 included studies involving 1065 people.In four studies, the randomised sequence was adequately generated and clearly described. In eight studies, allocation concealment was adequately generated and described. In four studies, the blinding procedures were sufficient. In six studies, incomplete outcome data were not adequately addressed. Furthermore, in 11 studies, the selective outcome reporting item was unclear because no study protocol was provided.Follow-up of studies comparing different osteotomy techniques was too short to measure treatment failure, which implicates revision to a knee arthroplasty.Four studies evaluated a closing wedge high tibial osteotomy (CW-HTO) with another high tibial osteotomy (aHTO). Based on these studies, the CW-HTO group had 1.8% (95% confidence interval (CI) -7.7% to 4.2%; low-quality evidence) more pain compared with the aHTO group; this finding was not statistically significant. Pooled function in the CW-HTO group was 0.5% (95% CI -3.8% to 2.8%; low-quality evidence) higher compared with the aHTO group; this finding was not statistically significant. No data on health-related quality of life and mortality were presented.Serious adverse events were reported in only four studies and were not significantly different (low-quality evidence) between groups. The reoperation rate were scored as early hardware removal because of pain and pin track infection due to the external fixator. Risk of reoperation was 2.6 (95% CI 1.5 to 4.5; low-quality evidence) times higher in the aHTO group compared with the CW-HTO group, and this finding was statistically significant.The quality of evidence for most outcomes comparing different osteotomy techniques was downgraded to low because of the numbers of available studies, the numbers of participants and limitations in design.Two studies compared high tibial osteotomy versus unicompartmental knee replacement. Treatment failure and pain and function scores were not different between groups after a mean follow-up of 7.5 years. The osteotomy group reported more adverse events when compared with the unicompartmental knee replacement group, but the difference was not statistically significant. No data on health-related quality of life and mortality were presented.No study compared an osteotomy versus conservative treatment.Ten included studies compared differences in perioperative or postoperative conditions after high tibial osteotomy. In most of these studies, no statistically significant differences in outcomes were noted between groups.

AUTHORS' CONCLUSIONS

The conclusion of this update did not change: Valgus high tibial osteotomy reduces pain and improves knee function in patients with medial compartmental osteoarthritis of the knee. However, this conclusion is based on within-group comparisons, not on non-operative controls. No evidence suggests differences between different osteotomy techniques. No evidence shows whether an osteotomy is more effective than alternative surgical treatment such as unicompartmental knee replacement or non-operative treatment. So far, the results of this updated review do not justify a conclusion on benefit of specific high tibial osteotomy technique for knee osteoarthritis.

Small subchondral drill holes improve marrow stimulation of articular cartilage defects

BACKGROUND

Subchondral drilling is an established marrow stimulation technique.

HYPOTHESIS

Osteochondral repair is improved when the subchondral bone is perforated with small drill holes, reflecting the physiological subchondral trabecular distance.

STUDY DESIGN

Controlled laboratory study.

METHODS

A rectangular full-thickness chondral defect was created in the trochlea of adult sheep (n = 13) and treated with 6 subchondral drillings of either 1.0 mm (reflective of the trabecular distance) or 1.8 mm in diameter. Osteochondral repair was assessed after 6 months in vivo by macroscopic, histological, and immunohistochemical analyses and by micro-computed tomography.

RESULTS

The application of 1.0-mm subchondral drill holes led to significantly improved histological matrix staining, cellular morphological characteristics, subchondral bone reconstitution, and average total histological score as well as significantly higher immunoreactivity to type II collagen and reduced immunoreactivity to type I collagen in the repair tissue compared with 1.8-mm drill holes. Analysis of osteoarthritic changes in the cartilage adjacent to the defects revealed no significant differences between treatment groups. Restoration of the microstructure of the subchondral bone plate below the chondral defects was significantly improved after 1.0-mm compared to 1.8-mm drilling, as shown by higher bone volume and reduced thickening of the subchondral bone plate. Likewise, the microarchitecture of the drilled subarticular spongiosa was better restored after 1.0-mm drilling, indicated by significantly higher bone volume and more and thinner trabeculae. Moreover, the bone mineral density of the subchondral bone in 1.0-mm drill holes was similar to the adjacent subchondral bone, whereas it was significantly reduced in 1.8-mm drill holes. No significant correlations existed between cartilage and subchondral bone repair.

CONCLUSION

Small subchondral drill holes that reflect the physiological trabecular distance improve osteochondral repair in a translational model more effectively than larger drill holes.

CLINICAL RELEVANCE

These results have important implications for the use of subchondral drilling for marrow stimulation, as they support the use of small-diameter bone-cutting devices.

Transitory improvement of articular cartilage characteristics after implantation of polylactide:polyglycolic acid (PLGA) scaffolds seeded with autologous mesenchymal stromal cells in a sheep model of critical-sized chondral defect

Clinical translation of emerging technologies aiming at cartilage resurfacing is hindered by neither the appropriate scaffold design nor the optimal cell source having been defined. Here, critical-sized, chondral-only focal defects were created in sheep and treated with clinical-grade, co-polymeric poly-lactide:polyglycolic acid scaffolds either alone or seeded with 3.3 × 10(6) ± 0.4 × 10(6) autologous bone marrow-derived mesenchymal stromal cells and studied over 12 month follow-up. An untreated group was included for comparison. Second-look arthroscopy performed at 4 months post-treatment evidenced the generation of neocartilage of better quality in those defects treated with cells. However, macroscopic scores in the cell-treated group declined significantly from 7.5 ± 2.3 at 4 months to 3.1 ± 2.6 (p = 0.0098) at 12 months post-treatment, whereas the other two experimental groups remained unaltered during 4-12 month post-treatment. The effectiveness of the cell-based approach proposed in this study is thus restricted to between months 1 and 4 post-treatment.

One-step repair for cartilage defects in a rabbit model: a technique combining the perforated decalcified cortical-cancellous bone matrix scaffold with microfracture

BACKGROUND

Cartilage repair still presents a challenge to clinicians and researchers alike. A more effective, simpler procedure that can produce hyaline-like cartilage is needed for articular cartilage repair.

HYPOTHESIS

A technique combining microfracture with a biomaterial scaffold of perforated decalcified cortical-cancellous bone matrix (DCCBM; composed of cortical and cancellous parts) would create a 1-step procedure for hyaline-like cartilage repair.

STUDY DESIGN

Controlled laboratory study.

METHODS

For the in vitro portion of this study, mesenchymal stem cells (MSCs) were isolated from bone marrow aspirates of New Zealand White rabbits. Scanning electron microscopy (SEM), confocal microscopy, and 1,9-dimethylmethylene blue assay were used to assess the attachment, proliferation, and cartilage matrix production of MSCs grown on a DCCBM scaffold. For the in vivo experiment, full-thickness defects were produced in the articular cartilage of the trochlear groove of 45 New Zealand White rabbits, and the rabbits were then assigned to 1 of 3 treatment groups: perforated DCCBM combined with microfracture (DCCBM+M group), perforated DCCBM alone (DCCBM group), and microfracture alone (M group). Five rabbits in each group were sacrificed at 6, 12, or 24 weeks after the operation, and the repair tissues were analyzed by histological examination, assessment of matrix staining, SEM, and nanoindentation of biomechanical properties.

RESULTS

The DCCBM+M group showed hyaline-like articular cartilage repair, and the repair tissues appeared to have better matrix staining and revealed biomechanical properties close to those of the normal cartilage. Compared with the DCCBM+M group, there was unsatisfactory repair tissues with less matrix staining in the DCCBM group and no matrix staining in the M group, as well as poor integration with normal cartilage and poor biomechanical properties.

CONCLUSION

The DCCBM scaffold is suitable for MSC growth and hyaline-like cartilage repair induction when combined with microfracture.

CLINICAL RELEVANCE

Microfracture combined with a DCCBM scaffold is a promising method that can be performed and adopted into clinical treatment for articular cartilage injuries.

One-step surgical procedure for the treatment of osteochondral defects with adipose-derived stem cells in a caprine knee defect: a pilot study

Regenerative therapies offer attractive alternatives for the treatment of osteochondral defects. Adipose-derived stromal vascular fraction (SVF) cells allow the development of one-step surgical procedures by their abundant availability and high frequency. In this pilot study we evaluated the in vivo safety, feasibility, and efficacy of this concept using scaffolds seeded with freshly isolated (SVF) or cultured adipose stem cells (ASCs), and compared these to their acellular counterparts. Osteochondral defects were created in medial condyles and trochlear grooves in knees of eight goats. Defects were filled with acellular collagen I/III scaffolds or scaffolds seeded with SVF cells or cultured ASCs. Osteochondral regeneration was evaluated after 1 and 4 months by macroscopy, immunohistochemistry, biomechanical analysis, microCT analysis, and biochemistry. After 1 month, no adverse effects were noted. Microscopic, but not macroscopic evaluation showed considerable yet not significant differences, with cell-loaded constructs showing more extensive regeneration. After 4 months, acellular constructs displayed increased regeneration, however, to a lesser degree than cell-treated constructs. The latter exhibited more extensive collagen type II, hyaline-like cartilage, and higher elastic moduli, and their glycosaminoglycan content in the cartilaginous layer better approached native tissue values. Moreover, their defect regions contained higher levels of regenerated, mature subchondral bone with more intense collagen type I staining. SVF cells tended to perform best on all parameters. In summary, this pilot study demonstrated the preclinical safety and feasibility of a one-step surgical procedure for osteochondral defect regeneration. Similar regeneration was found between freshly isolated SVF cells and cultured ASCs. Larger studies with longer follow-up are required to substantiate these findings.

Arthroscopic second generation autologous chondrocytes implantation associated with bone grafting for the treatment of knee osteochondritis dissecans: Results at 6 years

PURPOSE

The aim of this study was to analyze the clinical outcome obtained with arthroscopic second generation autologous chondrocyte implantation (ACI) associated with bone grafting for the treatment of knee osteochondritis dissecans (OCD) at medium term follow-up.

METHODS

Thirty-four knees affected by symptomatic OCD grade III or IV on the ICRS (International Cartilage Repair Society) scale were treated and prospectively evaluated at 12, 24 months of follow-up, and at a final mean 6 ± 1 years of follow-up. The mean age at treatment was 21 ± 6 years. The average size of the defects was 3 ± 1cm(2). Patients were evaluated with IKDC, EQ-VAS, and Tegner scores.

RESULTS

A statistically significant improvement in all scores was observed after the treatment. The IKDC subjective score improved from 38 ± 13 to 81 ± 20, and 91% of the knees were rated as normal or nearly normal in the objective IKDC at the final evaluation. EQ-VAS and Tegner scores showed a statistically significant linear trend of improvement over time passing from 52 ± 18 to 83 ± 14 and from 2 ± 1 to 5 ± 3, respectively, at 6 years' follow-up. A better outcome was obtained in men, sport active patients, and smaller lesions.

CONCLUSIONS

Second generation ACI associated with bone grafting is a valid treatment option for knee OCD and may offer a good and stable clinical outcome at mean 6 years of follow-up. Further studies are needed to confirm the results over time, and determine if there is only a symptomatic improvement, or if this procedure may also prevent or delay further knee degeneration.

Depth of subchondral perforation influences the outcome of bone marrow stimulation cartilage repair

Subchondral drilling and microfracture are bone marrow stimulation techniques commonly used for the treatment of cartilage defects. Few studies to date have examined the technical variants which may influence the success of the cartilage repair procedures. This study compared the effect of hole depth (6 mm vs. 2 mm) and hole type (drill vs. microfracture) on chondral defect repair using a mature rabbit model. Results from quantitative histomorphometry and histological scoring showed that deeper versus shallower drilling elicited a greater fill of the cartilage defect with a more hyaline character in the repair matrix indicated by significant improvement (p = 0.021) in the aggregate measure of increased cartilage defect fill, increased glycosaminoglycan and type II collagen content and reduced type I collagen content of total soft repair tissue. Compared to microfracture at the same 2 mm depth, drilling to 2 mm produced a similar quantity and quality of cartilage repair (p = 0.120) according to the aggregate indicator described above. We conclude that the depth of bone marrow stimulation can exert important influences on cartilage repair outcomes.

Preclinical animal models in trauma research

Preclinical modeling of human disease with animals has not been standardized for many common pathologic processes. Assorted animal models are being used to investigate the pathogenesis, prevention, and treatment of disease processes. Certainly it is difficult to interpret the current literature because there are diverse and often irrelevant models being implemented. Some models are used for reasons of size or ease rather than the true modeling of a physiological process. Application to granting agencies and design of animal studies is difficult without standardization of the ideal preclinical model for disease states. The current article addresses the preclinical animal modeling of osteoporosis, infection, bone defects, and cartilage injury. This article is a discussion of the current literature, commonly used models, and suggests preferred preclinical models for future research design.

Targeted delivery of non-viral vectors to cartilage in vivo using a chondrocyte-homing peptide identified by phage display

Gene therapy is a promising method for osteoarthritis and cartilage injury. However, specifically delivering target genes into chondrocytes is a great challenge because of their non-vascularity and the dense extracellular matrix of cartilage. In our study, we identified a chondrocyte-affinity peptide (CAP, DWRVIIPPRPSA) by phage display technology. Subsequent analysis suggests that the peptide can efficiently interact specifically with chondrocytes without any species specificity. Polyethylenimine (PEI) was covalently modified with CAP to construct a non-viral vector for cartilage-targeted therapy. To investigate the cartilage-targeting property of the CAP-modified vector, FITC-labeled CAP conjugated PEI/DNA particles were injected into rabbit knee joints, and visualized under confocal microscope. Higher concentrations of CAP-modified vector were detected in the cartilage and specifically taken up by chondrocytes compared with a randomly scrambled peptide (SP)-modified vector. To evaluate cartilage-targeting transfection efficiency, the GFP and luciferase genes were delivered into knee joints using CAP- and SP-modified PEI. Cartilage transfections mediated by CAP-modified PEI were much more efficient and specific than those by SP-modified PEI. This result suggests that CAP-modified PEI could be used as a specific cartilage-targeting vector for cartilage disorders.

Interaction of periosteal explants with articular chondrocytes alters expression profile of matrix metalloproteinases

Periosteal tissue is a source of growth factors and of osteochondral progenitor cells which makes it suitable for implantation in chondral defects as known in autologous chondrocyte implantation. The aim of this study was to determine the interaction between periosteal tissue and articular chondrocytes with respect to catabolic effectors such as matrix metalloproteinases (MMPs) and IL-6. Human articular chondrocytes were cultured for up to 28 days as micromass pellets in coculture either with physical contact to periosteal explants or allowing paracrine interactions only. Expression, secretion, and activation of MMPs and IL-6 were analyzed in chondrocytes, periosteum, and culture supernatants. Both coculture conditions influence gene expression levels of MMPs and IL-6 in a time-, culture-, and tissue-dependent manner. Coculturing of periosteum with chondrocytes promotes gene expression and secretion of IL-6. In periosteum, physical contact inhibits MMP-2 and MMP-13 gene expression while paracrine coculture induces expression of IL-6, MMP-2, -7, and -13. Pro-MMP-2, -7, and -13 were detected in supernatants of all culture regimens whereas pro-MMP-9 was secreted from periosteum only. As a balanced amount of MMP activity is likely required to achieve sufficient integration of the regenerate tissue with the surrounding healthy cartilage, an exceeding expression of proteinases might result in degradation, hypertrophy or rejection of the graft.

Autologous chondrocyte implantation: a long-term follow-up

BACKGROUND

The medium-term results of autologous chondrocyte implantation (ACI) have shown good to excellent outcomes for the majority of patients. However, no long-term results 10 to 20 years after the surgery have been reported.

HYPOTHESIS

Autologous chondrocyte implantation provides a durable solution to the treatment of full-thickness cartilage lesions of the knee, maintaining good clinical results even 10 to 20 years after implantation.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

In this uncontrolled study, questionnaires with the Lysholm, Tegner-Wallgren, Brittberg-Peterson, modified Cincinnati (Noyes), and Knee Injury and Osteoarthritis Outcome Score (KOOS) scores were sent to 341 patients. Preoperative Lysholm, Tegner-Wallgren, and Brittberg-Peterson scores were also retrieved when possible from patients' files. The patients were asked to grade their status during the past 10 years as better, worse, or unchanged. Finally, they were asked if they would do the operation again.

RESULTS

There were 224 of 341 patients who replied to our posted questionnaires and were assessed. The mean cartilage lesion size was 5.3 cm(2). Ten to 20 years after the implantation (mean, 12.8 years), 74% of the patients reported their status as better or the same as the previous years. There were 92% who were satisfied and would have the ACI again. The Lysholm, Tegner-Wallgren, and Brittberg-Peterson scores were improved compared with the preoperative values. The average Lysholm score improved from 60.3 preoperatively to 69.5 postoperatively, the Tegner from 7.2 to 8.2, and the Brittberg-Peterson from 59.4 to 40.9. At the final measurement, the KOOS score was on average 74.8 for pain, 63 for symptoms, 81 for activities of daily living (ADL), 41.5 for sports, and 49.3 for quality of life (QOL). The average Noyes score was 5.4. Patients with bipolar lesions had a worse final outcome than patients with multiple unipolar lesions. The presence of meniscal injuries before ACI or history of bone marrow procedures before the implantation did not appear to affect the final outcomes. The age at the time of the operation or the size of lesion did not seem to correlate with the final outcome.

CONCLUSION

Autologous chondrocyte implantation has emerged as an effective and durable solution for the treatment of large full-thickness cartilage and osteochondral lesions of the knee joint. Our study suggests that the clinical and functional outcomes remain high even 10 to 20 years after the implantation.

Effects of low-intensity pulsed ultrasound, dexamethasone/TGF-beta1 and/or BMP-2 on the transcriptional expression of genes in human mesenchymal stem cells: chondrogenic vs. osteogenic differentiation

The effects of low-intensity pulsed ultrasound (LIPUS) on the differentiation of human mesenchymal stem cells (hMSCs) were investigated in this study. hMSCs were subjected to LIPUS with or without dexamethasone/transforming growth factor-beta1 (TD) or bone morphogenetic protein-2 (BMP-2) and the effects of this treatment were assessed. TD-treated hMSCs exhibited characteristic chondrogenic morphology and increased messenger RNA (mRNA) expression of chondrogenic markers and LIPUS enhanced the chondrogenic differentiation of hMSCs treated with TD. The expression of Runx2, an osteogenic transcription factor was not altered in either TD treatment group; however, a significant increase was detected in the LIPUS only group. The osteogenic appearance exhibited 3 days after LIPUS and/or BMP-2 treatment. Increases in the mRNA expression levels of osteogenic markers, Runx2 and ALP were also detected. There was no additive or altered effect with combined LIPUS and BMP-2 treatment. LIPUS alone can increase osteogenic differentiation of hMSCs and LIPUS enhances TD-mediated chondrogenic differentiation of hMSCs. Clinically, LIPUS may differentially influence bone vs. cartilage repair.

Animal models for cartilage regeneration and repair

Articular cartilage injury and degeneration are leading causes of disability. Animal studies are critically important to developing effective treatments for cartilage injuries. This review focuses on the use of animal models for the study of the repair and regeneration of focal cartilage defects. Animals commonly used in cartilage repair studies include murine, lapine, canine, caprine, porcine, and equine models. There are advantages and disadvantages to each model. Small animal rodent and lapine models are cost effective, easy to house, and useful for pilot and proof-of-concept studies. The availability of transgenic and knockout mice provide opportunities for mechanistic in vivo study. Athymic mice and rats are additionally useful for evaluating the cartilage repair potential of human cells and tissues. Their small joint size, thin cartilage, and greater potential for intrinsic healing than humans, however, limit the translational value of small animal models. Large animal models with thicker articular cartilage permit study of both partial thickness and full thickness chondral repair, as well as osteochondral repair. Joint size and cartilage thickness for canine, caprine, and mini-pig models remain significantly smaller than that of humans. The repair and regeneration of chondral and osteochondral defects of size and volume comparable to that of clinically significant human lesions can be reliably studied primarily in equine models. While larger animals may more closely approximate the human clinical situation, they carry greater logistical, financial, and ethical considerations. A multifactorial analysis of each animal model should be carried out when planning in vivo studies. Ultimately, the scientific goals of the study will be critical in determining the appropriate animal model.

An experimental study on reconstruction of the condyle of the temporomandibular joint using free autogenous costal perichondrial grafts in rabbits

OBJECTIVE

The purpose of this study was to develop a new method to regenerate articular cartilage of the temporomandibular joint (TMJ) by transplantation of free autogenous costal perichondrium (PC).

STUDY DESIGN

In the study, 50 adult rabbits received the operation. For the surgery in the test group, the rabbits were randomly matched in pairs within the group and underwent the surgery of cross transplantation of costal PC after trimming the articular surface of the condyle. Operations were carried out in the same way in the experimental group except for PC transplantation. Instead, the suture was stitched in stratified order in the control group. Examination methods included observation of sections under the microscope, observation of specimens under the electron microscope, proliferating cell nuclear antigen (PCNA) staining, and biochemical analysis of glucuronic acid (GA) content and collagen content. The results of different groups were compared with ANOVA.

RESULTS

The transplanted homologous PC escaped observable immune repulsion so that it could survive to form new joint cartilage with approximately normal tissue structure and biochemical constitution. The reproduction process was similar to the normal one, but was prolonged a little. At the later stage, the degeneration and calcification in the basal layer increased. However, because of its limited scope, no apparent effect on cartilage growth and function was observed.

CONCLUSIONS

Homologous xenografting of free costal PC will not result in an apparent immunorejection of the host. Instead, the grafts can maintain their existence by obtaining nutrition from surrounding tissues and regenerate cartilage tissue.

Autologous engineering of cartilage

Treatment of full-thickness damage to hyaline cartilage is hampered by the limited availability of autologous healthy cartilage and the lengthy, cost-prohibitive cell isolation and expansion steps associated with autologous cartilage implantation (ACI). Here we report a strategy for de novo engineering of ectopic autologous cartilage (EAC) within the subperiosteal space (in vivo bioreactor), through the mere introduction of a biocompatible gel that might promote hypoxia-mediated chondrogenesis, thereby effectively overcoming the aforementioned limitations. The EAC is obtained within 3 wk post injection of the gel, and can be press-fit into an osteochondral defect where it undergoes remodeling with good lateral and subchondral integration. The implanted EAC showed no calcification even after 9 mo and attained an average O'Driscoll score of 11 (versus 4 for controls). An "on demand" autologous source of autologous cartilage with remodeling capacity is expected to significantly impact the clinical options in repair of trauma to articular cartilage.

Treatment of osteochondritis dissecans of the femoral condyle with autologous bone grafts and matrix-supported autologous chondrocytes

The objective of this study was to determine the clinical outcome of combined bone grafting and matrix-supported autologous chondrocyte transplantation in patients with osteochondritis dissecans of the knee. Between January 2003 and March 2005, 21 patients (mean age 29.33 years) with symptomatic osteochondritis dissecans (OCD) of the medial or lateral condyle (grade III or IV) of the knee underwent reconstruction of the joint surface by autologous bone grafts and matrix-supported autologous chondrocyte transplantation. Patients were followed up at three, six, 12 and 36 months to determine outcomes by clinical evaluation based on Lysholm score, IKDC and ICRS score. Clinical results showed a significant improvement of Lysholm-score and IKDC score. With respect to clinical assessment, 18 of 21 patients showed good or excellent results 36 months postoperatively. Our study suggests that treatment of OCD with autologous bone grafts and matrix-supported autologous chondrocytes is a possible alternative to osteochondral cylinder transfer or conventional ACT.

Preclinical animal models in single site cartilage defect testing: a systematic review

OBJECTIVE

Review the literature for single site cartilage defect research and evaluate the respective strengths and weaknesses of different preclinical animal models.

METHOD

A literature search for animal models evaluating single site cartilage defects was performed. Variables tabulated and analyzed included animal species, age and number, defect depth and diameter and study duration. Cluster analyses were then used to separate animals with only distal femoral defects into similar groups based on defect dimensions. Representative human studies were included allowing comparison of common clinical lesions to animal models. The suitability of each species for single site cartilage defect research and its relevance to clinical human practice is then discussed.

RESULTS

One hundred thirteen studies relating to single site cartilage defects were reviewed. Cluster analysis included 101 studies and placed the murine, laprine, ovine, canine, porcine and caprine models in group 1. Group 2 contained ovine, canine, porcine, caprine and equine models. Group 3 contained only equine models and humans. Species in each group are similar with regard to defect dimensions. Some species occur in multiple groups reflecting utilization of a variety defect sizes. We report and discuss factors to be considered when selecting a preclinical animal model for single site cartilage defect research.

DISCUSSION

Standardization of study design and outcome parameters would help to compare different studies evaluating various novel therapeutic concepts. Comparison to the human clinical counterpart during study design may help increase the predictive value of preclinical research using animal models and improve the process of developing efficacious therapies.

Cartilage repair: past and future--lessons for regenerative medicine

Since the first cell therapeutic study to repair articular cartilage defects in the knee in 1994, several clinical studies have been reported. An overview of the results of clinical studies did not conclusively show improvement over conventional methods, mainly because few studies reach level I of evidence for effects on middle or long term. However, these explorative trials have provided valuable information about study design, mechanisms of repair and clinical outcome and have revealed that much is still unknown and further improvements are required. Furthermore, cellular and molecular studies using new technologies such as cell tracking, gene arrays and proteomics have provided more insight in the cell biology and mechanisms of joint surface regeneration. Besides articular cartilage, cartilage of other anatomical locations as well as progenitor cells are now considered as alternative cell sources. Growth Factor research has revealed some information on optimal conditions to support cartilage repair. Thus, there is hope for improvement. In order to obtain more robust and reproducible results, more detailed information is needed on many aspects including the fate of the cells, choice of cell type and culture parameters. As for the clinical aspects, it becomes clear that careful selection of patient groups is an important input parameter that should be optimized for each application. In addition, the study outcome parameters should be improved. Although reduced pain and improved function are, from the patient's perspective, the most important outcomes, there is a need for more structure/tissue-related outcome measures. Ideally, criteria and/or markers to identify patients at risk and responders to treatment are the ultimate goal for these more sophisticated regenerative approaches in joint surface repair in particular, and regenerative medicine in general.

Human periosteum-derived cells from elderly patients as a source for cartilage tissue engineering?

The aim of this study was to establish the potential of human periosteum-derived cells from elderly patients as a cell source for cartilage tissue engineering by optimizing culture conditions for both proliferation and differentiation. Periosteum was obtained from the tibiae of nine patients. Biopsies were prepared for routine histological examination. Periosteum-derived cells were allowed to grow out from the remaining tissue, and were expanded in minimum essential medium containing D-valine (MEM-DV). Fetal bovine serum (FBS) or substitutes, fibroblast growth factor-2 (FGF-2), insulin-like growth factor-1 (IGF-1) and non-essential amino acids were added to study proliferation. For differentiation of cells, serum-free medium was used supplemented with one or more isoforms of transforming growth factor-beta (TGFbeta) and/or IGF-1. Samples were analysed for expression of collagens type I, II and X by competitive RT-PCR, immunohistochemically, and histologically using Alcian blue staining. In all samples the cambium layer could hardly be detected. Periosteum-derived cells proliferated in serum-containing MEM-DV. Optimal proliferation was found when this medium was supplemented with 100 ng/ml FGF-2 and non-essential amino acids. Chondrogenesis was detected in 59% of micromasses that were cultured with TGFbeta isomers, and in 83% of the samples cultured in media to which two TGFbeta isoforms were added. Periosteum from elderly humans (mean age 66, range 41-76 years) has chondrogenic potential and remains an attractive cell source for cartilage tissue engineering. By expanding cells in MEM-DV, the selection of progenitor cells might be favoured, which would result in a higher cartilage yield for tissue engineering applications.

Development of partial-thickness articular cartilage injury in a rabbit model

In humans, partial-thickness cartilage lesions frequently result in premature osteoarthritis. While rabbits often are used as a model for partial-thickness cartilage lesions, the natural course of cartilage surrounding such a lesion is largely unknown. We developed a rabbit model of a chronic partial-thickness cartilage defect and asked whether these defects led to (1) deterioration of surrounding cartilage macroscopically and microscopically (increased Mankin score) and (2) disturbances in proteoglycan metabolism. In 55 rabbits, we created a 4-mm-diameter partial-thickness cartilage defect on one medial femoral condyle. The surrounding cartilage was characterized during the course of 26 weeks. Contralateral knees were sham-operated. In experimental knees, we found cartilage softening and fibrillation at 13 and 26 weeks. High Mankin scores observed at 1 week were partially restored at 13 weeks but worsened later and were most pronounced at 26 weeks. Mankin scores in the experimental groups were worse at 1 and 26 weeks when compared with the sham groups. Mankin scores at 26 weeks improved compared with 1 week in the sham groups. Disturbances in proteoglycan metabolism were less evident. In this rabbit model, a partial-thickness cartilage lesion resulted in early markers of degenerative changes resembling the human situation.

Osteotomy for treating knee osteoarthritis

BACKGROUND

Patients with unicompartmental osteoarthritis of the knee can be treated with a correction osteotomy. The goal of the correction osteotomy is to transfer the load bearing from the pathologic to the normal compartment of the knee. A successful outcome of the osteotomy relies on proper patient selection, stage of osteoarthritis, achievement and maintenance of adequate operative correction. This is an update of the original review published in Issue 1, 2005.

OBJECTIVES

To assess the effectiveness and safety of an osteotomy for treating osteoarthritis of the knee.

SEARCH STRATEGY

Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE (Current contents, Health STAR) up to October 2002 in the original review and in the update until May 2007. Reference lists of identified trials were screened.

SELECTION CRITERIA

Randomised and controlled clinical trials comparing a high tibial osteotomy or a distal femoral osteotomy in patients with unicompartmental osteoarthritis of the medial or lateral compartment of the knee.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, extracted data and assessed trial quality. Due to heterogeneity of the studies, pooling of outcome measures was not possible.

MAIN RESULTS

Thirteen studies involving over 693 people were included; 11 studies were included in the first version and two studies and one longer follow-up study were included in this update. All studies concerned a valgus high tibial osteotomy (HTO) for medial compartment osteoarthritis of the knee. Six studies, in which two studies were included in this update, compared two techniques of HTO. One study compared HTO alone versus HTO with additional treatment. Four studies compared within the same type of HTO, different peri-operative conditions (two studies) or two different types of post-operative treatment (two studies). Two studies, including the longer follow up, compared HTO with unicompartmental joint replacement. No study compared an osteotomy with conservative treatment. Most studies showed improvement of the patient (less pain and improvement of function scores) after osteotomy surgery, but in the majority of the studies there was no significant difference with other operative treatment (other technique of HTO/ unicompartmental joint replacement). Overall, the methodological quality was low.

AUTHORS' CONCLUSIONS

Based on 13 studies, we conclude that there is 'silver' level evidence (www.cochranemsk.org) that valgus HTO improves knee function and reduces pain. There is no evidence whether an osteotomy is more effective than conservative treatment and the results so far do not justify a conclusion about effectiveness of specific surgical techniques.