Platelet-rich plasma (PRP) as therapy for cartilage, tendon and muscle damage - German working group position statement.

PURPOSE: Platelet rich plasma (PRP) is widely used in orthopaedics, but is still heavily debated. Therefore, a survey among the German "Working Group for Clinical Tissue Regeneration" of the German Society of Orthopaedics and Traumatology was conducted to achieve a consensus about the current therapeutical potential of PRP. METHODS: A first survey (n = 65 experts, all orthopaedic/trauma surgeons) was conducted (n = 13 questions). Following, a second round (n = 40 experts) was conducted with 31 questions to achieve consensus in 5 categories: three most common indications, PRP application, future research areas. RESULTS: Therapeutic PRP application was regarded as useful (89%), possibly even more important in the future (90%). Most common indications were tendon pathologies (77%), osteoarthritis (OA) (68%), muscle injuries (57%) and cartilage damage (51%). Consensus was reached in 16/31 statements. The application of PRP for early knee OA (Kellgren-Lawrence grade II) was regarded as potentially useful, as well as for acute and chronic tendinopathies. For chronic lesions (cartilage, tendons), multiple injections (2-4) were seen preferable to singular injections. However, no sufficient data exists on the time interval between the injections. Standardization of PRP preparation, application, frequency, as well as determining the range of indication is strongly recommended. CONCLUSIONS: There is a need of further standardization of the PRP preparation methods, indication and application protocols for knee OA and other indications, which must be further evaluated in basic science studies and randomized controlled clinical trials. LEVEL OF EVIDENCE: Consensus of expert opinion, Level V.

A novel quantitative metric for joint space width: data from the Osteoarthritis Initiative (OAI).

OBJECTIVE: Joint space width (JSW) has been the gold standard to assess loss of cartilage in knee osteoarthritis (OA). Here we describe a novel quantitative measure of joint space width: standardized JSW (stdJSW). We assess the performance of this quantitative metric for JSW at tracking Osteoarthritis Research Society International (OARSI) joint space narrowing grade (JSN) changes and provide reference values for different JSN grades and their annual change. METHODS: We collected 18,934 individual knee images along with JSW and JSN readings from baseline up to month 48 (4 follow-ups) from the OAI study. Standardized JSW and 12-month JSN grade changes were calculated for each knee. For each JSN grade and 12-month grade change, the distribution of JSW loss was calculated for JSW and stdJSW. Area under the ROC curves was calculated on discrimination between different JSN grades for JSW and stdJSW. Standardized response mean (SRM) was used to compare the responsiveness of the two measures to changes in JSN grade. RESULTS: The areas under the receiver operating characteristic (ROC) curve (AUC) for stdJSW at discriminating between successive JSN grades were AUCstdJSW = 0.87, 0.95, and 0.96, for JSN>0, JSN>1 and JSN>2, respectively, whereas these were AUCfJSW = 0.79, 0.90, 0.98 for absolute JSW. We find that standardized JSW is significantly more responsive than absolute JSW, as measured by the SRM. CONCLUSIONS: Our results show that stdJSW outperforms absolute JSW at discriminating and tracking changes in JSN and further that this effect is in part because stdJSW cancels JSW variations attributed to patient height variations.

Tribocorrosion of a CoCrMo alloy sliding against articular cartilage and the impact of metal ion release on chondrocytes.

Partial knee replacement and hemiarthroplasty are some of the orthopedic procedures resulting in a metal on cartilage interface. As metal implant material, CoCrMo based alloys are commonly used. The aim of the present study is to assess the role of biotribocorrosion on the CoCrMo-cartilage interface with an emphasis on metal release during sliding contact. The biotribocorrosion experiments were performed under controlled electrochemical conditions using a floating cell with a three electrode set up coupled to a microtribometer. Throughout the experiment the coefficient of friction and the open circuit potential were monitored. Analyses of the electrolyte after the experiment show that metal release can occur during sliding contact of CoCrMo alloy against articular cartilage despite the extraordinary low coefficient of friction measured. Metal release is attributed to changes in passive layer caused at the onset of sliding. The released metal was found to be forming compounds with potential cytotoxicity. Since the presence of metal ions in the cartilage matrix can potentially lead to cell apoptosis, the metabolic activity of human osteoarthritic chondrocytes (2D-cultures) was investigated in the presence of phosphate buffered saline containing metal ions using XTT-assay. The experiments indicate that critical concentrations of Co ions lead to a significant decrease in chondrocyte metabolic activity. Therefore, biotribocorrosion is a mechanism that can occur in partial replacements and lead to chondrocyte apoptosis thus playing a role in the observed accelerated degradation of the remaining cartilage tissue after the mentioned orthopedic procedures. STATEMENT OF SIGNIFICANCE: Partial replacements provide an alternative to total joint replacements. This procedure is less invasive, allows a faster rehabilitation and provides a better function of the joint. However, the remaining native cartilage experiences accelerated degradation when in contact with metallic implant components. This work investigates the role of tribocorrosion at the metal-cartilage interface during sliding. Tribocorrosion is a degradation process that can alter significantly the wear rates experienced by metallic implants and lead to the release of metal ions and particles. The released metal can form compounds with potential cytotoxicity on cartilage tissue. The knowledge gained in this work will serve to understand the mechanisms behind the failure of partial replacements and develop future biomaterials with an enhanced lifetime.

Effects of a lower extremity exercise program on gait biomechanics and clinical outcomes in children and adolescents with obesity: A randomized controlled trial.

BACKGROUND: Research highlights the detrimental effects of obesity on gait biomechanics and the accompanied risk of lower-extremity skeletal malalignments, increased joint stress, pain and discomfort. Individuals with obesity typically show increased knee valgus angles combined with an increased step width. Accompanying muscular dysfunctions impede their ability to compensate for these alterations, especially in the frontal plane. To date, no studies are available, which evaluated the potential effects of an exercise program (EP) in reducing these unfavorable biomechanical changes. RESEARCH QUESTIONS: Is a 12-week EP, which includes hip abductor and knee extensor strength exercises and fosters dynamic knee alignment, effective in positively altering gait biomechanics in children and adolescents with obesity? METHODS: This study was a randomized controlled trial having children and adolescents with obesity assigned to an EP (n = 19) or control (n = 16) group. Pain, self-rated knee function, muscle strength and 3D gait analysis during walking and stair climbing were evaluated. RESULTS: Results indicate that the EP was able to increase muscular strength especially in the hip abductors. In addition, children from the EP group walked with less maximum hip adduction and reduced pelvic drop during weight acceptance at follow-up. No changes were present in self-rated knee function, pain or discomfort. SIGNIFICANCE: Even though effects were small, results indicate that an EP is an effective short-term possibility to counteract the progressive development of biomechanical malalignments of the lower extremity. Clinical parameters indicated that the program was feasible. Nonetheless, low adherence highlights the need to develop more attractive programs. CLINICAL TRIALS REG. NO: clinicaltrials.gov (NCT02545764).

Matrix-associated autologous chondrocyte transplantation in a compartmentalized early stage of osteoarthritis.

OBJECTIVE: Cartilage restoration in joints with an early stage of osteoarthritis (OA) is an important clinical challenge. In this study, a compartmentalized, early-stage OA was generated surgically in sheep stifle joints, and this model was used to evaluate a matrix-associated cell transplantation approach for cartilage repair. METHOD: Eighteen sheep were operated twice. During the first operation, a unicompartmental OA in a stable joint was induced by creating a critical-size defect. The second operation served as a regeneration procedure. The eighteen sheep were divided into three groups. One group was treated with spongialization (SPONGIO), while the two others had spongialization followed by implantation of a hyaluronan matrix with (MACT) or without chondrocytes (MATRIX). The follow-up took place 4 months after the second operation. Gross Assessment of Joint Changes score and Brittberg score were used for the macroscopic evaluation, Mankin score, O'Driscoll score, and immunohistochemistry for collagen type I and type II for histological evaluation. RESULTS: The MACT group achieved significantly better results in both macroscopic and histological examinations. In the regeneration area, a Mankin score of 7.88 (6.20; 9.55) [mean (upper 95% confidence interval; lower 95% confidence interval)] was reached in the MACT group, 10.38 (8.03; 12.72) in the MATRIX group, and 10.33 (8.80; 11.87) in the SPONGIO group. The O'Driscoll score revealed a highly significant difference in the degree of defect repair: 15.92 (14.58; 17.25) for the MACT group compared to the two other groups [5.04 (1.21; 8.87) MATRIX and 6.58 (5.17; 8.00) SPONGIO; P < 0.0001]. CONCLUSION: This study demonstrates promising results toward the development of a biological regeneration technique for early-stage OA.

Microfracture in the Ankle: Clinical Results and MRI with T2-Mapping at 3.0 T after 1 to 8 Years.

BACKGROUND: Microfracture (MFX) is frequently used to treat deep cartilage defects in the ankle; however, the data on repair tissue (RT) quality after MFX are very limited at this time. T2-mapping at 3 T has been optimized for the ankle and can be used to noninvasively evaluate cartilage collagen and water content. The aim of this study was to determine if the RT after MFX in the ankle had T2 properties similar to the adjacent reference cartilage (RC). METHODS: Fourteen cases after MFX in the ankle were assessed with morphological MRI and T2-mapping at 3 T. The American Orthopaedic Foot and Ankle Society (AOFAS) score and a modified Cinicinnati Knee Rating System rating were used to evaluate the clinical outcome. The MRI protocol included a 3-dimensional sequence and a proton-density sequence for morphological evaluation and a multiecho spin echo sequence for T2-mapping. Region of interest analyses were carried out in accordance with the morphological images to ensure complete coverage of the defect site. RESULTS: Both clinical scores demonstrated significant improvement at the time of the MR examination (P < 0.001). RT T2 was 49.3 ± 10.1 (range, 35.7-69.3) milliseconds, and RC T2 was 49.9 ± 8.2 (range, 38.4-63.7) milliseconds (P = 0.838). Relative T2 (rT2) was 1.00 ± 0.20 (range, 0.72-1.36). CONCLUSION: MFX in the ankle can provide RT with T2 properties similar to adjacent cartilage.

[Differential diagnostics of the musculoskeletal system in sports medicine]. / Differenzialdiagnostische Untersuchung in der Sportmedizin des Bewegungsapparats.

The positive effects of sports on the cardiovascular and musculoskeleal systems are widely accepted. Nevertheless, sports also can cause injury and overuse leading to sport-specific problems, which are often a challenge in diagnosing and treatment. The history of the sport-related injury is crucial for further differential diagnosis. Careful inspection, palpation and functional testing can reveal the possible pathology and lead to an effective strategy in the diagnostic assessment using radiographic tools such as sonography, X-ray and MR imaging (MRI). In muscle and tendon injuries sonography can provide ready to use information concerning muscle tears and tendon ruptures or degenerative lesions. Plain X-rays give a good overview on joint conditions regarding the bone and sometimes have to be completed by focused enlargement of the critical structure, especially in stress fractures and small bone lesions. MRT is the gold standard in the evaluation of interarticular and extra-articular sport-related pathologies, however, an exact clinical diagnosis allows a more effective investigation protocol. Profound knowledge of possible sport-specific injury and overuse patterns is necessary to detect lesions of the musculoskeletal system in active athletes and to use the fitting radiographic strategy for confirmation. The exact diagnosis is the prerequisite for initiating the appropriate treatment and a fast sports medical rehabilitation process.

T2 mapping and dGEMRIC after autologous chondrocyte implantation with a fibrin-based scaffold in the knee: preliminary results.

OBJECTIVE: To assess repair tissue (RT) after the implantation of BioCartII, an autologous chondrocyte implantation (ACI) technique with a fibrin-hyaluronan polymer as scaffold. T2 mapping and delayed Gadolinium Enhanced Magnetic Resonance Imaging of Cartilage (dGEMRIC) were used to gain first data on the biochemical properties of BioCartII RT in vivo. METHODS: T2 mapping and dGEMRIC were performed at 3T in five patients (six knee joints) who had undergone ACI 15-27 months before. T2 maps were obtained using a pixel wise, mono-exponential non-negative least squares fit analysis. For quantitative T1 mapping a dual flip angle 3D GRE sequence was used and T1 maps were calculated pre- and post-contrast using IDL software. Subsequent region of interest analysis was carried out in comparison with morphologic MRI. RESULTS: A spatial variation of T2 values in both hyaline, normal cartilage (NC) and RT was found. Mean RT T2 values and mean NC T2 values did not differ significantly. Relative T2 values were calculated from global RT and NC T2 and showed a small range (0.84-1.07). The relative delta relaxation rates (rDeltaR1) obtained from the T1 maps had a wider range (0.77-4.91). CONCLUSION: T2 mapping and dGEMRIC provided complementary information on the biochemical properties of the repair tissue. BioCartII apparently can provide RT similar to hyaline articular cartilage and may become a less-invasive alternative to ACI with a periosteal flap.

Lectin binding patterns reflect the phenotypic status of in vitro chondrocyte models.

In vitro studies using chondrocyte cell cultures have increased our understanding of cartilage physiology and the altered chondrocytic cell phenotype in joint diseases. Beside the use of primary cells isolated from cartilage specimens of donors, immortalized chondrocyte cell lines such as C-28/I2 and T/C-28a2 have facilitated reproducible and standardized experiments. Although carbohydrate structures appear of significance for cartilage function, the contribution of the chondrocyte glycocalyx to matrix assembly and alterations of the chondrocyte phenotype is poorly understood. Therefore, the present study aimed to evaluate the glycoprofile of primary human chondrocytes as well as of C-28/I2 and T/C-28a2 cells in culture. First, the chondrocytic phenotype of primary and immortalized cells was assessed using real-time reverse transcriptase polymerase chain reaction, immunofluorescence, and glycosaminoglycans staining. Then, a panel of lectins was selected to probe for a range of oligosaccharide sequences determining specific products of the O-glycosylation and N-glycosylation pathways. We found that differences in the molecular phenotype between primary chondrocytes and the immortalized chondrocyte cell models C-28/I2 and T/C-28a2 are reflected in the glycoprofile of the cells. In this regard, the glycocalyx of immortalized chondrocytes was characterized by reduced levels of high-mannose type and sialic acid-capped N-glycans as well as increased fucosylated O-glycosylation products. In summary, the present report emphasizes the glycophenotype as an integral part of the chondrocyte phenotype and points at a significant role of the glycophenotype in chondrocyte differentiation.

Results of chondrocyte implantation with a fibrin-hyaluronan matrix: a preliminary study.

UNLABELLED: Fibrin, a homologous polymer, is the natural scaffold of wound healing and therefore a candidate as a carrier for cell transplantation. We explored a novel matrix-based implant cartilage repair composed of both fibrin and hyaluronan in a defined ratio that takes advantage of the biological and mechanical properties of these two elements. The matrix was seeded with autologous chondrocytes expanded in the presence of a proprietary growth factor variant designed to preserve their chondrogenic potential. We prospectively followed eight patients with symptomatic-chronic cartilage defects treated with this carrier. Patients had arthroscopy to harvest autologous chondrocytes then grown in autologous serum. Chondrocytes were cultured in the presence of the FGF variant and then seeded on the fibrin-hyaluronan matrix. About 4 weeks following biopsy, the patients underwent implantation of the constructs by miniarthrotomy. Three of the eight patients had transient effusion. Clinical performance was measured by Lysholm and IKDC scores, MRI, and the need for secondary surgery. The clinical outcome of a 1-year followup demonstrated increase of clinical scores. The MRI followup showed good filling of the defect with tissue having the imaging appearance of cartilage in all patients. Apart from the transient effusion in three patients we observed no other adverse events during the followup. LEVEL OF EVIDENCE: Level IV, therapeutic study.

T2 mapping in the knee after microfracture at 3.0 T: correlation of global T2 values and clinical outcome - preliminary results.

OBJECTIVE: The aim of our study was to correlate global T2 values of microfracture repair tissue (RT) with clinical outcome in the knee joint. METHODS: We assessed 24 patients treated with microfracture in the knee joint. Magnetic resonance (MR) examinations were performed on a 3T MR unit, T2 relaxation times were obtained with a multi-echo spin-echo technique. T2 maps were obtained using a pixel wise, mono-exponential non-negative least squares fit analysis. Slices covering the cartilage RT were selected and region of interest analysis was done. An individual T2 index was calculated with global mean T2 of the RT and global mean T2 of normal, hyaline cartilage. The Lysholm score and the International Knee Documentation Committee (IKDC) knee evaluation forms were used for the assessment of clinical outcome. Bivariate correlation analysis and a paired, two tailed t test were used for statistics. RESULTS: Global T2 values of the RT [mean 49.8ms, standards deviation (SD) 7.5] differed significantly (P<0.001) from global T2 values of normal, hyaline cartilage (mean 58.5ms, SD 7.0). The T2 index ranged from 61.3 to 101.5. We found the T2 index to correlate with outcome of the Lysholm score (r(s)=0.641, P<0.001) and the IKDC subjective knee evaluation form (r(s)=0.549, P=0.005), whereas there was no correlation with the IKDC knee form (r(s)=-0.284, P=0.179). CONCLUSION: These findings indicate that T2 mapping is sensitive to assess RT function and provides additional information to morphologic MRI in the monitoring of microfracture.

Differential cartilaginous tissue formation by human synovial membrane, fat pad, meniscus cells and articular chondrocytes.

OBJECTIVE: To identify an appropriate cell source for the generation of meniscus substitutes, among those which would be available by arthroscopy of injured knee joints. METHODS: Human inner meniscus cells, fat pad cells (FPC), synovial membrane cells (SMC) and articular chondrocytes (AC) were expanded with or without specific growth factors (Transforming growth factor-beta1, Fibroblast growth factor-2 and Platelet-derived growth factor bb, TFP) and then induced to form three-dimensional cartilaginous tissues in pellet cultures, or using a hyaluronan-based scaffold (Hyaff-11), in culture or in nude mice. Human native menisci were assessed as reference. RESULTS: Cell expansion with TFP enhanced glycosaminoglycan (GAG) deposition by all cell types (up to 4.1-fold) and messenger RNA expression of collagen type II by FPC and SMC (up to 472-fold) following pellet culture. In all models, tissues generated by AC contained the highest fractions of GAG (up to 1.9% of wet weight) and were positively stained for collagen type II (specific of the inner avascular region of meniscus), type IV (mainly present in the outer vascularized region of meniscus) and types I, III and VI (common to both meniscus regions). Instead, inner meniscus, FPC and SMC developed tissues containing negligible GAG and no detectable collagen type II protein. Tissues generated by AC remained biochemically and phenotypically stable upon ectopic implantation. CONCLUSIONS: Under our experimental conditions, only AC generated tissues containing relevant amounts of GAG and with cell phenotypes compatible with those of the inner and outer meniscus regions. Instead, the other investigated cell sources formed tissues resembling only the outer region of meniscus. It remains to be determined whether grafts based on AC will have the ability to reach the complex structural and functional organization typical of meniscus tissue.

A tissue engineering approach to meniscus regeneration in a sheep model.

OBJECTIVE: Regeneration of the meniscal tissue occurs to a limited extent, and the loss of meniscal tissue leads to osteoarthritis. A new biomaterial consisting of hyaluronic acid and polycaprolactone was used as a meniscus substitute in sheep to evaluate the properties of the implant material with regard to size, biomechanical stability, tissue ingrowth, and integration. METHODS: Eight sheep (right stifle joints) were treated with three total and three partial meniscus replacements while two meniscectomies served as empty controls. The animals were euthanized after 6 weeks. The specimens were assessed by gross inspection and histology, and compared with the nonoperated left joints. RESULTS: The surgical technique was found to be feasible. The implants remained in position, did not tear, and showed excellent tissue ingrowth to the capsule. Tissue integration was also observed between the original meniscus and the implant. However, graft compression and extrusion occurred. The histological investigation revealed tissue formation, cellular infiltration and vascularization. Cartilage degeneration was more severe in the operated joints. CONCLUSION: The present study shows promising results concerning the qualities of this biomaterial with regard to implantation technique, stability and tissue ingrowth.

Three-year clinical outcome after chondrocyte transplantation using a hyaluronan matrix for cartilage repair.

Repair of articular cartilage represents a significant clinical problem and although various new techniques - including the use of autologous chondrocytes - have been developed within the last century the clinical efficacy of these procedures is still discussed controversially. Although autologous chondrocyte transplantation (ACT) has been widely used with success, it has several inherent limitations, including its invasive nature and problems related to the use of the periosteal flap. To overcome these problems autologous chondrocytes transplantation combined with the use of biodegradable scaffolds has received wide attention. Among these, a hyaluronan-based scaffold has been found useful for inducing hyaline cartilage regeneration. In the present study, we have investigated the mid-term efficacy and safety of Hyalograft C grafts in a group of 36 patients undergoing surgery for chronic cartilage lesions of the knee. Clinical Outcome was assessed prospectively before and at 12, 24, and 36 months after surgery. No major adverse events have been reported during the 3-year follow-up. Significant improvements of the evaluated scores were observed (P < 0.02) at 1 year and a continued increase of clinical performance was evident at 2 and 3 years follow-up. Patients under 30 years of age with single lesions showed statistically significant improvements at all follow-up visits compared to those over 30 with multiple defects (P < 0.01). Hyalograft C compares favorably with classic ACT and is particularly indicated in younger patients with single lesions. The graft can be implanted through a miniarthrotomy and needs no additional fixation with sutures except optional fibrin gluing at the defect borders. These results suggest that Hyalograft C is a valid alternative to ACT.

[Snowboarding. History--injuries--risks--new materials--tournament on-site services--prevention]. / Snowboarden Geschichte -- Verletzungen -- Risiken -- Materialneuigkeiten -- Wettkampfbetreuung -- Prävention.

Since the 1998 Olympic Winter Games in Nagano, snowboarding has been established as a popular winter sport for youth and adults. The most frequently affected body region reported in many studies on snowboarding injuries are the wrists accounting for more than 50% of severe injuries, especially in beginners. Wrist braces are effective in protecting snowboarding beginners against wrist injuries. Male snowboarders up to the age of 16 and female snowboarders over the age of 25 have a higher risk of injury. Snowboarders should not use ski boots and should be careful with rented equipment. Systems providing body and limb protection and also snowboard-specific helmets can reduce the injury risk for alpine racers, freestylers, and also freeriders. Snowboard training is important to prevent injuries especially for beginners, and icy slopes should be avoided.

Marrow stimulation and chondrocyte transplantation using a collagen matrix for cartilage repair.

OBJECTIVE: The purpose of the study was to determine whether the implantation of a scaffold would facilitate cartilage repair after microfracture in sheep over a period of 12 months. Furthermore, we investigated the effect of additional autologous cell augmentation of the implanted constructs. METHODS: Two chondral defects were produced in the medial femoral condyle of sheep without penetrating the subchondral bone. Twenty-seven sheep were divided into the following groups: seven served as untreated controls (Group 1), microfracture was created in 20 animals, seven of them without further treatment (Group 2), in six sheep the defects were additionally covered with a porcine collagen matrix (Group 3), and in seven animals the matrix was augmented with cultured autologous chondrocytes (Group 4). After 4 (11 sheep) and 12 months (16 sheep), the filling of the defects, tissue types, and semiquantitative scores were determined. RESULTS: The untreated defects revealed the least amount of defect fill. Defects treated with microfractures achieved better defect fill, while the additional use of the matrix did not increase the defect fill. The largest quantity of reparative tissue was found in the cell-augmented group. Semiquantitative scores were best in the cell-augmented group. CONCLUSION: Microfracture treatment was observed to enhance the healing response. The implantation of a cell-seeded matrix further improved the outcome. The implantation of a collagen matrix alone did not enhance repair. Autologous cell implantation appears to be a very important aspect of the tissue engineering approach to cartilage defects.

Repair of articular cartilage defects treated by microfracture and a three-dimensional collagen matrix.

The objective of our study was to evaluate the behavior of ovine chondrocytes and bone marrow stromal cells (BMSC) on a matrix comprising type-I, -II, and -III collagen in vitro, and the healing of chondral defects in an ovine model treated with the matrix, either unseeded or seeded with autologous chondrocytes, combined with microfracture treatment. For in vitro investigation, ovine chondrocytes and BMSC were seeded on the matrix and cultured at different time points. Histological analysis, immunohistochemistry, biochemical assays for glycosaminoglycans, and real-time quantitative PCR for collagens were performed. The animal study described here included 22 chondral defects in 11 sheep, divided into four treatment groups. Group A: microfracture and collagen matrix seeded with chondrocytes; B: microfracture and unseeded matrices; C: microfracture; D: untreated defects. All animals were sacrificed 16 weeks after implantation, and a histomorphometrical and qualitative evaluation of the defects was performed. The in vitro investigation revealed viable cells up to 3 weeks; chondrocytes had a predominantly round morphology, produced glycosaminoglycans, and expressed both collagen markers, whereas BMSC stained positive for antibodies against type-II collagen; however, no mRNA for type-II collagen was amplified. All treatment groups of the animal model showed better defect filling compared to untreated knees. The cell-seeded group had the greatest quantity of repair tissue and the largest quantity of hyaline-like tissue. Although the collagen matrix is an adequate environment for BMSC in vitro, the additionally implanted unseeded collagen matrix did not increase the repair response after microfracture in chondral defects. Only the matrices seeded with autologous cells in combination with microfracture were able to facilitate the regeneration of hyaline-like cartilage.

[Mid-term results of autologous chondrocyte transplantation in knee and ankle. A one- to six-year follow-up study]. / Mittelfristige Ergebnisse mit der autologen Knorpelzelltransplantation an Knie- und SprunggelenkEin- bis Sechsjahresergebnisse.

BACKGROUND: The reimplantation of autologous chondrocytes is a new technique in reconstruction of cartilage defects; initial results achieved with this technique have been promising. In an arthroscopic procedure, scales of cartilage are obtained from intact cartilage. The chondrocytes are then multiplied in special laboratories. A few weeks later, in a second procedure, the cartilage defect is filled with the cell suspension and closed with a flap of periosteum. METHOD: At our department, autologous chondrocyte transplantation (ACT) has been used in 10 patients since 1996, in 6 cases in the knee joint, and in 4 cases in the ankle joint. The mean age of the patients was 30 years. The mean size of the defect was 4 cm(2). In 4 patients, a parallel surgical procedure was required at the time of removal. RESULTS: The mean duration of follow-up was 21/2 years. Six patients had good to excellent results, 3 patients had moderate results, and one patient a poor result. The modified Cincinnati rating scale was improved from 2.4 to 7.1 points, and the Lysholm score from 59.2 to 86.6 points. The AOFAS score for ankle joints had improved from 33 to 76. CONCLUSION: We were able to show that ACT achieves improvement in the knee as well as ankle joint in the majority of patients. ACT appears to be a promising therapeutic concept for both joints.

[Indications and implementation of recommendations of the working group "Tissue Regeneration and Tissue Substitutes" for autologous chondrocyte transplantation (ACT)]. / Indikations- und Durchführungsempfehlungen der Arbeitsgemeinschaft "Geweberegeneration und Gewebeersatz" zur Autologen Chondrozyten-Transplantation (ACT).

For the treatment of full-thickness articular cartilage lesions of the knee joint, as a result of trauma or osteochondritis dissecans, a variety of biological reconstruction techniques have been developed. Different studies, some of which were performed as randomised, prospective clinical studies, showed that the autologous chondrocyte transplantation (ACT) provides the most satisfying and reliable method of cartilage reconstruction in the adult when applied to defects exceeding 4 cm (2). Based on these results, ACT seems to be of economic benefit, as the risk of developing osteoarthritis correlates significantly with the size of the cartilage defect, when not treated properly and in time. Surveying the studies on basic scientific aspects of ACT, cartilage defect animal models and clinical studies, it can be concluded that clinical results of ACT depend on a variety of factors. In this review, published by the joined advisory board of the German Societies of Traumatology (DGU) and Orthopaedic Surgery (DGOOC), we summarize the current knowledge available and the state of the art concerning ACT. Especially we discuss the advantages of different procedures, methods for treating knee cartilage defects and factors that influence the outcome of the different treatment regimens, with the aim to develop guidelines for the correct indication and application of the ACT.

[Osteosarcoma and Ewing's sarcoma--The most frequent malignant bone tumors in children--therapy and outcome]. / Osteosarkom und Ewing-Sarkom - die häufigsten Knochentumoren bei Kindern: Therapie und Ergebnisse.

BACKGROUND: Osteosarcoma and Ewing's sarcoma are the most frequent malignant bone tumors in children and young adults with relatively poor overall survival rates. METHODS: Between January 1980 and December 1994, 175 children with osteosarcoma and 64 children with Ewing's sarcoma were treated at the author's institution. 22 children had synchronous metastases, 19 patients had a pathologic fracture. Both groups were treated systemically with chemotherapy regimens (COSS and CESS). Local therapy was amputation or tumor resection and endoprosthetic replacement or biological reconstruction with wide or radical resection margins. In case of Ewing's sarcoma in 35 patients postoperative radiation therapy was done. RESULTS: Five-year overall survival rate for osteosarcoma and Ewing's sarcoma patients is about 63 %, ten-year survival rate for osteosarcoma patients is 60.2 %, for Ewing's sarcoma patients 54.5 %. Prognostic factors significantly influencing overall survival rates are tumor response to chemotherapy (p values = 0.0056 and 0.013, respectively), surgical treatment with adequate resection margins (p value = 0.0001 for osteosarcoma patients) and development of postoperative metastases (p value = 0.0001 for both groups). CONCLUSION: For both groups of malignant bone tumors systemic chemotherapy as well as adequate surgical therapy are necessary to reduce the rates of local recurrences and to achieve better survival rates.