A comparative study of 3 different cartilage repair techniques.

PURPOSE: The value of cell-free techniques in the treatment of cartilage defects remains under debate. In this study, cartilage repair of full-thickness chondral defects in the knees of Goettinger minipigs was assessed by treatment with a cell-free collagen type-I gel or a collagen type-I gel seeded with autologous chondrocytes. As a control, abrasion arthroplasty was included. METHODS: In 18 adult Goettinger minipigs, three full-thickness chondral defects were created in one knee of the hind leg. They were either treated with a cell-free collagen gel, a collagen gel seeded with 2 × 10(5)/ml chondrocytes, or left untreated. All animals were allowed unlimited weight bearing. At 6, 12, and 52 weeks, 6 animals were sacrificed. Immediately after recovery, a non-destructive biomechanical testing was performed. The repair tissue quality was evaluated histologically, and the O'Driscoll score was calculated. RESULTS: After 6 weeks, a high number of cells migrated into the initially cell-free collagen gel. After 1 year, a hyaline-like repair tissue in both groups has been created. As assessed by O'Driscoll scoring and col-II staining, repair tissue quality of the initially cell-free gel was equal to defects treated by cell-seeded collagen gel implantation after 1 year. All untreated control defects displayed a fibrous repair tissue. The mechanical properties represented by the e-modulus were inconsistent in the course of the study. CONCLUSIONS: The implantation of a cell-free collagen type-I gel can lead to a high-quality repair tissue in the Goettinger minipig that equals a cell-based procedure after 1 year postoperatively. This study demonstrates the high chondrogenic potential of the applied collagen gel, which might help to overcome the disadvantages inherent in conventional cartilage tissue engineering methods.

A cell-free collagen type I device for the treatment of focal cartilage defects.

The purpose of this study was to evaluate the potential value of a cell-free collagen type I gel plug for the treatment of focal cartilage defects. Cellular migration and proliferation was addressed in vitro, and the formation of repair tissue in a nude mouse-based defect model. A cell-free plug made of collagen type I was placed in the center of an incubation plate. Surrounding space was filled with a collagen type I gel (Arthro Kinetics, Esslingen, Germany) seeded with 2 x 10(5) human articular chondrocytes/mL gel. After cultivation for up to 6 weeks in vitro, samples were subject to histological and immunohistochemical staining and gene expression analysis. Subsequently, chondral defects of human osteochondral blocks were treated with the plug, and specimens were cultivated subcutaneously in nude mice for 6 weeks. The repair tissue was evaluated macroscopically, and collagen type II production was investigated immunohistochemically. In vitro, morphology of immigrated cells did not show any differences, as did collagen type II gene expression. After 4 weeks, the plug was homogeneously inhabited. After 6 weeks of cultivation in nude mice, collagen gel plug treatment led to a macroscopically excellent repair tissue. Histological staining revealed a tight bonding, and the collagen gel plug started to be remodeled. We conclude that the novel collagen gel plug device offers an environment favorable for the migration of articular chondrocytes and leads to a good-quality repair tissue in the nude mouse model. The arthroscopic transplantation of a collagen gel plug may be one option in the treatment of focal cartilage defects.

Millicurrent stimulation of human articular chondrocytes cultivated in a collagen type-I gel and of human osteochondral explants.

BACKGROUND: Here we investigate the effect of millicurrent treatment on human chondrocytes cultivated in a collagen gel matrix and on human osteochondral explants. METHODS: Human chondrocytes from osteoarthritic knee joints were enzymatically released and transferred into a collagen type-I gel. Osteochondral explants and cell-seeded gel samples were cultivated in-vitro for three weeks. Samples of the verum groups were stimulated every two days by millicurrent treatment (3 mA, sinusoidal signal of 312 Hz amplitude modulated by two super-imposed signals of 0.28 Hz), while control samples remained unaffected. After recovery, collagen type-I, type-II, aggrecan, interleukin-1beta, IL-6, TNFalpha and MMP13 were examined by immunohistochemistry and by real time PCR. RESULTS: With regard to the immunostainings 3 D gel samples and osteochondral explants did not show any differences between treatment and control group. The expression of all investigated genes of the 3 D gel samples was elevated following millicurrent treatment. While osteochondral explant gene expression of col-I, col-II and Il-1beta was nearly unaffected, aggrecan gene expression was elevated. Following millicurrent treatment, IL-6, TNFalpha, and MMP13 gene expression decreased. In general, the standard deviations of the gene expression data were high, resulting in rarely significant results. CONCLUSIONS: We conclude that millicurrent stimulation of human osteoarthritic chondrocytes cultivated in a 3 D collagen gel and of osteochondral explants directly influences cell metabolism.

Effects of low concentrated BMP-7 administered by co-cultivation or plasmid transfection on human osteoarthritic chondrocytes.

INTRODUCTION: While BMP-7 has proven to be one of the most potent growth factors in cartilage tissue engineering, protein concentration and route of administration remain a matter of debate. Here we investigated the effects of a low concentration of BMP-7 on human osteoarthritic chondrocytes administered by protein co-cultivation and plasmid transfection. METHODS: Freshly released (P0) or in vitro propagated chondrocytes (P2) were cultivated in a collagen type-I gel for 3 weeks in vitro or in nude mice. Seeded chondrocytes were treated with 50 ng/mL BMP-7 directly added to the medium or were subject to transient BMP-7 plasmid transfection prior to gel cultivation. Untreated specimens served as a control. After recovery, samples were investigated by histological and immunohistochemical staining and real-time PCR. RESULTS: In vitro, collagen type-II protein production was enhanced, and it was stored mainly pericellularly. Collagen type-II and aggrecan gene expression were enhanced in both treatment groups. After nude mouse cultivation, col-II protein production was further enhanced, but specimens of the BMP-7 transfection group revealed a clustering of col-II positive cells. Gene expression was strongly upregulated, chondrocyte number was increased and the differentiated phenotype prevailed. In general, freshly released chondrocytes (P0) proved to be superior to chondrocytes pre-amplified in vitro (P2). CONCLUSIONS: Both BMP-7 co-cultivation and plasmid transfection of human osteoarthritic chondrocytes led to improved cartilage repair tissue. Nevertheless, the col-II distribution following BMP-7 co-cultivation was homogeneous, while samples produced by transient transfection revealed a col-II clustering.

BMP-2 incorporated in a tricalcium phosphate bone substitute enhances bone remodeling in sheep.

Bone morphogenetic protein-2 (BMP-2) is a well-known osteoinductive protein, which requires a carrier for local application. As an alternative to the previously described carriers, an in situ hardening, resorbable, and osteoconductive beta-tricalcium phosphate cement (TCP) is tested. Trepanation defects in the bovine distal femoral epiphysis are filled with a composite consisting of TCP and 200 microg rhBMP-2 per cm3 TCP, autologous bone graft, pure TCP, or left empty. A radiological follow-up is performed after 7 weeks and 3 months. The sheep are euthanized and bone samples are analyzed by microradiography, histology, and histomorphometry. Microradiography and histology show similar results for pure TCP and the composite. The defects are filled with trabecular bone and newly formed bone is in close contact with the remaining TCP-particles. The majority of the cement is resorbed, in the composite group the amount of remaining cement particles is reduced. Defects treated with autologous bone graft are filled completely, while untreated defects shows only a small amount of bone originating from the rim of the defect. Histomorphometry of the defects treated with pure TCP shows a significantly increased bone content in comparison to defects treated with the composite or autologous bone graft. Analysis of the remaining cement particles shows significantly less cement in the TCP/rhBMP-2 group in comparison to pure TCP. The sum of bone and cement content in the rhBMP-2 group shows amounts comparable to the calcified structures found following autologous bone grafting. The addition of rhBMP-2 to the TCP leads to faster remodeling of the defect comparable to autologous bone graft, while defects treated with pure TCP are not completely remodeled.

Perthes' or Perthes' resembling disease in 13-month-old boy.

Onset of Perthes' disease is reported frequently from the age of 2 years. Latest publications showed cases with onset of this disease in infancy at ages of 17 and 18 months. We report the case of a 13-month-old boy, who presented with left-sided limping. Radiological examination showed reduced height and fragmentation of the femoral head. Magnetic resonance imaging showed the typical signs of an avascular necrosis. Follow-up was done after 3, 7 and 15 months. Plain radiography showed the femoral head in a state of reparation. This is the youngest documented case of Legg-Calvé-Perthes' disease and is discussed under consideration of the current literature.

Lack of effect on bone healing of injectable BMP-2 augmented hyaluronic acid.

INTRODUCTION: Autologous bone graft is the gold standard for the filling of large osseous defects. Because of its limited supply and complications such as pain, bleeding or infection, the development of alternative bone substitutes has been the subject of several studies. In clinical practice, the most commonly used bone substitutes are calcium phosphates like hydroxyapatite or tricalcium phosphate. With the aim to improve the osseointegration of these materials, growth factors such as bone morphogenetic protein-2 (BMP-2) have been added. Preferably, an injectable bone substitute should be made available. Hyaluronic acid is a component of the extracellular matrix of many tissues, including bone. We examined the bone regenerative effect of commercially available, injectable hyaluronic acid (Hyalart) with and without addition of bone morphogenetic protein-2 (BMP-2). MATERIALS AND METHODS: Trepanation defects of 9.4 mm diameter in the intercondylar groove of sheep femora were filled with pure and augmented (200 microg BMP-2) hyaluronic acid. As controls, empty defects and defects treated with autologous bone graft harvested from the contralateral side were used. After 3 months, the defects were analysed by fluorescence microscopy after intravital fluorescence staining, contact microradiography, histology and histomorphometry. RESULTS: Treatment of the defects with loaded and unloaded hyaluronic acid resulted in a significant lack of bone formation inside the defects. Untreated defects showed an amount of 5.1% newly formed bone, and defects treated with autologous bone graft revealed a bone content of 20%. The difference between both groups was statistically significant (P < 0.05). Furthermore, there was neither a remarkable effect in the periphery of the defects nor ectopic bone formation. CONCLUSION: The application of the used injectable hyaluronic acid (Hyalart) with and without BMP-2 is not advantageous as sole bone substitute for the filling of osseous defects.

Amphiphilic bonder improves adhesion at the acrylic bone cement-bone interface of cemented acetabular components in total hip arthroplasty: in vivo tests in an ovine model.

INTRODUCTION: Even following the introduction of the "third generation" cementing technique, an improvement of the fixation of the acetabular component similar to that of the femoral has not been shown in clinical studies. The goal of the present study was to achieve a better stability with the use of an amphiphilic bonder while preserving the mechanically important subchondral sclerosis. MATERIALS AND METHODS: In a total of 20 sheep, a cemented total hip replacement was implanted. In the treatment group (n = 10), the implantation was carried out following surface conditioning of the acetabular bed with an amphiphilic bonder. All the sheep were followed for 9 months. To assess the biocompatibility, the osseous ingrowth at the cement-bone interface was depicted with the help of an in vivo fluorescent marking of the osteoblasts. Additionally, conventional radiographs were obtained over the course of treatment. Finally, the ovine pelvic regions were split following a standardized technique allowing for histological evaluation of the cement-bone interfaces. RESULTS: The acetabular components of the treatment group revealed a stable cement-bone compound. In the control group, the implants were easily dislodged from their beds. This finding was consistent with the radiological and histological results, which had revealed increased, progressive lytic radiolucent lines and the interposition of fibrous tissue at the cement-bone interface in the control group compared to the treatment group. The bonder was biocompatible. CONCLUSION: Following the application of the bonder, the cemented acetabular components revealed an improved stability without signs of inflammation or neoplasia in a viable acetabular osseous bed. With the help of this technique, the in vivo longevities of cemented acetabular components can be increased in the clinical setting without sacrificing the biomechanical relevant subchondral sclerosis.

Assessment of leech therapy for knee osteoarthritis: a randomized study.

BACKGROUND AND PURPOSE: Symptomatic treatment of osteoarthritis of the knee with leeches is presently undergoing a renaissance. Previous studies have shown methodical weaknesses. In the present study patients were blinded regarding the treatment, and a control group was included to explore possible differences in various subjective clinical scores and intake of pain medication over time between leech therapy and placebo control. PATIENTS AND METHODS: 113 patients with advanced osteoarthritis of the knee were included. The patients were randomized to a single treatment group, group I (single leech application, n = 38), a double treatment group, group II (double application, n = 35), and a control group (n = 40). The second treatment in group II took place after an interval of 4 weeks. The treatment in the control group was simulated with the help of an "artificial leech". Results were documented with the KOOS and WOMAC scores and also a visual analog scale (VAS) for pain. Changes in the use of pain medication were monitored over 26 weeks. RESULTS: An improvement in KOOS and WOMAC scores, and also in VAS, was found in all 3 groups following treatment. These improvements were statistically significant for treatment groups I and II during the complete follow-up period. The reduction in individual requirements for pain medication was also statistically significant. The greatest improvement was seen in the group treated twice with the leeches, with a long-term reduction of joint stiffness and improved function in the activities of daily living. INTERPRETATION: Leech therapy can reduce symptoms caused by osteoarthritis. Repeated use of the leeches appears to improve the long-term results. We have not determined whether the positive outcome of the leech therapy is caused by active substances released during the leeching, the placebo effect, or the high expectations placed on this unusual treatment form.

Measures for reducing ultra-high-molecular-weight polyethylene wear in total knee replacement: a simulator study.

Wear of ultra-high-molecular-weight polyethylene (UHM-WPE) inlays is associated with aseptic loosening in total knee replacement (TKR). The aim of this study was to investigate the in vitro performance of a TKR system that combines several measures to decrease UHMWPE wear. Tests were carried out on a BPK-S Integration system (R&D, P. Brehm Chirurgie-Mechanik, Weisendorf, Germany) according to ISO 14,243-1 in a knee joint simulator. Calf serum with a high protein concentration of 30 g/l was chosen as the test lubricant. PE wear was measured gravimetrically. Particle analysis was performed by scanning electron microscopy, with measurement of particle size and shape. Low mean wear rates of 1.20 mg per million cycles were found for the fixed bearing type and 2.47 mg per million cycles for the rotating-platform bearing design. Anteroposterior deflection was low. The contact areas for both types of bearings were large and showed a constant pattern throughout the test. Backside wear was obvious on rotating platforms. Particle analysis revealed equally sized and round-shaped particles in both types of bearings (fixed, 0.35 microm; mobile, 0.32 microm). In conclusion, the combination of design features and surface modifications of the BPK-S integration TKR system leads to low gravimetric UHMWPE wear.

[ Improvement of femoral bone-cement adhesion in cemented revision hip arthroplasty by application of an amphiphilic bonder in a dynamic femur expulsion testing in vitro ]. / Steigerung der femuralen Knochen-Knochenzement-Verbundfestigkeit in der zementierten Revisionshüftendoprothetik durch einen amphiphilen Knochenhaftvermittler im dynamischen in-vitro Ausstossversuch.

Cemented femoral stems have shown decreased longevity compared to cementless implants in hip revision arthroplasty. The aim of this study was to evaluate the effect of an amphiphilic bonder on bone cement stability in a biomechanical femur expulsion test. A simplified hip simulator test setup with idealised femur stem specimens was carried out. The stems were implanted into bovine femurs (group 1: no bonder, n=10; group 2: bonder including glutaraldehyde, n=10; group 3: bonder without glutaraldehyde, n=10). A dynamic loading (maximum load: 800 N; minimum load: 100 N; frequency: 3 Hz; 105 cycles) was performed. Subsequently, the stem specimens were expulsed axially out of their implant beds and maximum load at failure was recorded. The static controls showed a mean maximum load to failure of 4123 N in group 1, 8357.5 N in group 2 and 5830.8 N in group 3. After dynamic loading, the specimens of group 2 reached the highest load to failure (8191.5 N), followed by group 3 (5649.5 N) and group 1 (3462 N), respectively. In group 2, we observed nine periprosthetic fractures at a load of 8400 N without signs of interface loosening. Application of an amphiphilic bonder led to a significant improvement of bonding stability, especially when glutaraldehyde was added to the bonder. This technique might offer an increased longevity of cemented femur revision stems in total hip replacement.

Uncemented femoral revision arthroplasty using the modular revision prosthesis MRP-TITAN revision stem.

OBJECTIVE: Restoration of a painless hip joint capable of bearing weight by uncemented implantation of a rotationally stable, modular revision stem anchored in the diaphysis. INDICATIONS: Prosthetic stem loosening with osteolytic bone defects (defect classification types I-III according to Paprosky). Material failure with broken prosthesis. Sub- and/or periprosthetic femoral fractures. Tumors. CONTRAINDICATIONS: Extensive osteolysis preventing diaphyseal anchorage of the prosthesis. SURGICAL TECHNIQUE: Transgluteal approach to the hip joint. Removal of the loose prosthetic stem and, if cemented, the bone cement as well. Excision of intramedullary granulation tissue. Reaming of the medullary cavity with flexible reaming shafts and form-fit, uncemented implantation of the star-shaped modular revision stem with diaphyseal press fit. If there is extensive loss of metaphyseal bone stock, augmentation with autogenous/allogenic bone should be performed. POSTOPERATIVE MANAGEMENT: Mobilization on two underarm crutches from the 1st postoperative day. Removal of the Redon drains after 48 h. Partial loading with 20 kg for 6 weeks postoperatively. If plain radiographs show unchanged seating of the prosthesis after 6 weeks, loading can be increased by 10 kg per week until full weight bearing is achieved; thrombosis prophylaxis is continued throughout. Radiologic checkups after 3, 6, and 12 months. After that, the patient should be checked annually. RESULTS: 45 patients (n = 48 prostheses) with an average age of 67.2 years (min.-max. 42.4-87.4 years) were investigated. The average implantation time of the Modular Revision Prosthesis MRP-TITAN revision stem was 4.7 years (min.-max. 1.0-9.0 years). The Harris Hip Score for Paprosky bone defect types I-III had increased from 25.6 preoperatively to 71.4 postoperatively at the time of the final follow-up (< or = 0.05). Extensively defective bone was diagnosed preoperatively in 32 patients (> or = Paprosky IIB). Plain radiographs showed stable anchorage without migration in 44 patients. In one case, the stem (implantation time 2.36 years) was replaced due to increasing axial subsidence (> or = 5 mm). Good integration of bone graft with subsequent defect regeneration was seen in all patients with bone transplant (n = 30). Postoperative dislocation occurred in six patients and required closed reduction in four cases. Open reduction was performed in two patients, whereby the external rotation angle of the prosthetic neck was corrected without dismantling the distally anchored prosthetic stem components. The mechanical failure rate over the follow-up period of 9 years was one out of the 48 prospectively investigated prostheses. Rate of survival according to Kaplan-Meier was 97%.

In vitro comparison of six different matrix systems for the cultivation of human chondrocytes.

In recent years, a great variety of different matrix systems for the cultivation of chondrocytes have been developed. Although some of these scaffolds show promising experimental results in vitro, the potential clinical value remains unclear. In this comparative study, we propagated human articular chondrocytes precultivated in monolayer culture on six different scaffolds (collagen gels, membranes and sponges) under standardized in vitro conditions. Mechanical properties of the matrix systems were not improved significantly by cultivation of human chondrocytes under the given in vitro conditions. The gel systems (CaReS, Ars Artho, Germany and Atelocollagen, Koken, Japan) showed a homogeneous cell distribution; chondrocytes propagated on Chondro-Gide (Geistlich Biomaterials, Switzerland) and Integra membranes (Integra, USA) were building multilayers. Only few cells penetrated the two Atelocollagen honeycomb sponges (Koken, Japan). During cultivation, chondrocytes propagated on all systems showed a partial morphological redifferentiation, which was best with regard to the gel systems. In general, only small amounts of collagen type-II protein could be detected in the pericellular region and chondrocytes failed to build a territorial matrix. During the first two weeks of cultivation, the two gel systems showed a significantly higher collagen type-II gene expression and a lower collagen type-I gene expression than the other investigated matrix systems. Although collagen gels seem to be superior when dealing with deep cartilage defects, membrane systems might rather be useful in improving conventional autologous chondrocyte transplantation or in combination with gel systems.

Femoral cement extraction in revision total hip arthroplasty--an in vitro study comparing computer-assisted freehand-navigated cement removal to conventional cement extraction.

BACKGROUND: Revision surgery of cemented femoral stems in total hip arthroplasty is gaining more and more importance, but cement removal in revision hip arthroplasty may be technically challenging. Conventional manual cement removal can be time consuming and be associated with complications such as cortical perforation, fracture, or bone loss. The aim of this study was to investigate the practicability of computer-navigated cement removal. MATERIAL AND METHODS: In an in vitro study, we examined the removal of the bone cement out of composite bones. To evaluate accuracy, the bones were scanned before and after cement removal with the ISO-C three-dimensional C-arm computed tomography system to determine the amount of unremoved cement and the loss of bone stock. The data of freehand-navigated cement removal is compared to conventionally extracted cement using levers and drills under X-ray control. RESULTS: The mean time for cement removal was 29 ± 5 min for the conventional method and 32 ± 8 min for the freehand-navigated cement removal. Here, excepting the preparatory examinations, the navigated cement removal only took 13 ± 5 min. The measured temperature during polymerization was 36 ± 5 °C and during navigated cement removal was 37 ± 8 °C. In the distal part of the femur, cement removal was more accurate with the conventional method compared to the navigated one. CONCLUSION: The freehand-navigated cement removal, with the exception of the preparatory examinations, is time saving compared to the conventional method. However, a potential for technical development especially for the milling device and accuracy exist.

Cell-free repair of small cartilage defects in the Goettinger minipig: the effects of BMP-7 continuously released by poly(lactic-co-glycolid acid) microspheres.

OBJECTIVE: Cartilage repair of full-thickness chondral defects in the knees of Goettinger minipigs was assessed after treatment with cell-free collagen type-I gel with or without additional BMP-7 loaded poly(lactic-co-glycolid acid) microspheres. METHODS: Two full-thickness chondral defects were created in the trochlear groove of one hind leg knee in six Goettinger minipigs. Six defects were treated with a cell-free collagen type-I gel plug of 10 mm, the corresponding six defects were treated with a cell-free collagen type-I plug with poly(lactic-co-glycolid acid) microspheres loaded with recombinant BMP-7 (100 ng/ml gel). After 1 year, the animals were sacrificed. Immediately after recovery, non-destructive biomechanical testing was performed. The repair tissue quality was evaluated by immunohistochemistry and the O'Driscoll score was calculated. RESULTS: After 1 year, a robust cellular migration into the cell-free collagen gel plugs occurred and a hyaline-like repair tissue was found. Collagen type-II production and cellular organisation were higher in the BMP-7 microsphere group. The determination of the E-modulus, creep and relaxation revealed that mechanical properties of the BMP-7 microsphere group in summary were closer to control hyaline cartilage. CONCLUSIONS: While all specimens revealed a homogeneous cellular distribution, ECM production, cellular organisation and mechanical properties were enhanced by continuous BMP-7 release.

In vitro elution characteristics of gentamicin and vancomycin from synthetic bone graft substitutes.

OBJECTS: Beta tricalciumphosphate pellets loaded with individualized antibiotics may represent novel options in the treatment of osteomyelitis and infectious bone disease. Here, the in vitro antibiotic elution of vancomycin and gentamicin from the synthetic bone graft substitutes Cerasorb(®) and Cerasorb M(®) was tested. METHODS: Antibiotic elution and concentration of gentamcin and vancomycin were measured using photometrically-based measurement and homogeneous particle-enhanced turbidimetric inhibition immunoassays (PETINIA). RESULTS: Initially both materials showed a high release of the loaded antibiotics, with Cerasorb M(®) showing lower release levels for gentamicin and vancomycin than Cerasorb(®). Gentamicin concentrations of Cerasorb M granules and Cerasorb were below the minimum detectiontreshold until day four and six of the experiment respectively. The vancomycin release-level followed a similar pattern, although the vancomycin concentration eluted by Cerasorb M(®) granules stayed above the detection threshold during the experimental time. CONCLUSIONS: Cerasorb(®) and Cersorb M(®) may represent a new treatment option in osteomyelitis and infectious bone disease.

A prospective multicenter study on the outcome of type I collagen hydrogel-based autologous chondrocyte implantation (CaReS) for the repair of articular cartilage defects in the knee.

BACKGROUND: The Cartilage Regeneration System (CaReS) is a novel matrix-associated autologous chondrocyte implantation (ACI) technique for the treatment of chondral and osteochondral lesions (Outerbridge grades III and IV). For this technology, no expansion of the chondrocytes in a monolayer culture is needed, and a homogeneous cell distribution within the gel is guaranteed. PURPOSE: To report a prospective multicenter study of matrix-associated ACI of the knee using a new type I collagen hydrogel (CaReS). STUDY DESIGN: Case series; Level of evidence, 4. METHODS: From 2003 to 2008, 116 patients (49 women and 67 men; mean age, 32.5 ± 8.9 years) had CaReS implantation of the knee in 9 different centers. On the basis of the International Cartilage Repair Society (ICRS) Cartilage Injury Evaluation Package 2000, the International Knee Documentation Committee (IKDC) score, pain score (visual analog scale [VAS]), SF-36 score, overall treatment satisfaction and the IKDC functional status were evaluated. Patient follow-up was performed at 3, 6, and 12 months after surgery and annually thereafter. Mean follow-up was 30.2 ± 17.4 months (range, 12-60 months). There were 67 defects of the medial condyle, 14 of the lateral, 22 of the patella/trochlea, and 3 of the tibial plateau, and 10 patients had 2 lesions. The mean defect size was 5.4 ± 2.4 cm(2). Thirty percent of the defects were <4 cm(2) and 70% were >4 cm(2). RESULTS: The IKDC score improved significantly from 42.4 ± 13.8 preoperatively to 70.5 ± 18.7 (P < .001) at latest follow-up. Global pain level significantly decreased (P < .001) from 6.7 ± 2.2 preoperatively to 3.2 ± 3.1 at latest follow-up. There also was a significant increase of both components of the SF-36 score. The overall treatment satisfaction was judged as very good or good in 88% by the surgeon and 80% by the patient. The IKDC functional knee status was grade I in 23.4%, II in 56.3%, III in 17.2%, and IV in 3.1% of the patients. CONCLUSION: Matrix-associated ACI employing the CaReS technology for the treatment of chondral or osteochondral defects of the knee is a safe and clinically effective treatment that yields significant functional improvement and improvement in pain level. However, further investigation is necessary to determine the long-term viability and clinical outcome of this procedure.

Condensed cellular seeded collagen gel as an improved biomaterial for tissue engineering of articular cartilage.

Three-dimensional autologous chondrocyte implantation based on collagen gel as matrix scaffold has become a clinically applied treatment for focal defects of articular cartilage. However, the low biomechanical properties of collagen gel makes intraoperative handling difficult and creates the risk of early damages to the vulnerable implant. The aim of the study was to create a stabilized form of collagen gel and to evaluate its biomechanical and biochemical properties.Collagen type-I gel was seeded with human articular chondrocytes. 20 samples were subject to condensation which was achieved mechanically by compression and filtration. Control samples were left uncondensed. From both types of gels 10 samples were used for initial biomechanical evaluation by means of unconfined compression and 10 samples were cultivated under standard conditions in vitro. Following cultivation the samples were evaluated by conventional histology and immunohistochemistry. The proliferation rate was calculated and matrix gene expression was quantified by real-time PCR.The biomechanical tests revealed a higher force carrying capacity of the condensed specimens. Strain rate dependency and relaxation was seen in both types of collagen gel representing viscoelastic material properties. Cells embedded within the condensed collagen gel were able to produce extracellular matrix proteins and showed proliferation.Condensed collagen gel represents a mechanically improved type of biomaterial which is suitable for three-dimensional autologous chondrocyte implantation.

How to store autologous bone graft perioperatively: an in vitro study.

INTRODUCTION: Autologous bone graft is the golden standard for bone grafting, but little is known about the influence of various preservation techniques used during surgery immediately following harvest on the osseous structures and graft vitality. Several studies focussed on the optimal treatment of the bone during harvest and implantation, but only few examined the intraoperative storage conditions on the back table. The aim of our study was to examine the influence of various intraoperative preservation techniques on human cancellous bone at different points to optimize the storage during surgery. MATERIALS AND METHODS: Cancellous bone was harvested during hip arthroplasty and stored for 2 and 4 h under dry conditions, inside a swab moistened with saline solution or in saline solution, 5% glucose solution or culture medium. After the storage period, the bone was cultured and examined 7 days after the first cells grew out in one of these groups. Following the identification of the cells as osteoblast-like cells, the cultures were analysed by fluorescence staining, cell count and the XTT-test. RESULTS: Fluorescence staining revealed no avital cells in all groups. Dry storage of the bone led to significantly lower cell metabolism after 2 h compared to saline solution and 5% glucose solution. The same was true after 4 h dry storage compared to the moistened swab, and glucose and culture medium. Cell count was significantly lower after 2 h of dry storage compared to saline solution and culture medium. CONCLUSIONS: Perioperative storage of cancellous bone under dry conditions should be avoided. The bone graft should be stored in saline or 5% glucose solution or a moistened swab.

A bFGF/TCP-composite inhibits bone formation in a sheep model.

Basic fibroblast growth factor is a well known osteostimulative protein. The effects of basic fibroblast growth factor are dose-dependent and, when used with a carrier, influenced by the release kinetics. Aim of our study was to determine the effects of a composite of basic fibroblast growth factor and a newly developed, in situ setting tricalcium phosphate (TCP) cement. A trepanation defect in the distal femoral epiphysis of Merino-Mix sheep with a diameter of 9.4 mm and 10 mm depth was filled with the in situ setting TCP cement combined with 0 or 200 microg of bFGF/cm(3) TCP, autologous bone graft or left empty. The sheep were euthanized after 3 months. The defect and the periimplant area were examined by microradiography, histology, and histomorphometry. The data was analyzed with the help of the Wilcoxon and Kruskal-Wallis tests. Defects filled with TCP with or without bFGF showed a close bone-cement contact. The histomorphometric analysis revealed that the addition of bFGF inhibited the ingrowth of bone significantly, while the resorption of the cement was not influenced. In conclusion, the clinical application of this bFGF/TCP-composite does not seem promising. The reason for the inhibition of new bone formation will be discussed, but requires further investigation.