Cell-free repair of small cartilage defects in the Goettinger minipig: which defect size is possible?

PURPOSE: Cartilage repair of full-thickness chondral defects in the knees of Goettinger minipigs was assessed by treatment with cell-free collagen type-I gel plugs of three different sizes. METHODS: In 6 adult Goettinger minipigs, three full-thickness chondral defects were created in the trochlear groove of one knee of the hind leg. These defects were treated with a cell-free collagen type-I gel plug of 8, 10, or 12 mm diameter. All animals were allowed unlimited weight bearing. After 1 year, the animals were killed. Immediately after recovery, a non-destructive biomechanical testing was performed. The repair tissue quality was evaluated immunohistologically, collagen type-II protein was quantified, and a semiquantitative score (O'Driscoll score) was calculated. RESULTS: After 1 year, a high number of cells migrated into the initially cell-free collagen gel plugs and a hyaline-like repair tissue had been created. The O'Driscoll scores were: 8 mm, 21.2 (SD, 2.8); 10 mm, 21.5 (SD, 1.6); and 12 mm, 22.3 (SD, 1.0). The determination of the e-modulus, creep and relaxation revealed that mechanical properties of the two smaller defects were closer to unaffected hyaline cartilage. CONCLUSIONS: As cell-free collagen type-I gel plugs of all three different sizes created hyaline-like repair tissue, this system seems suitable for the treatment of even larger defects.

[Reconstruction of osteochondral defects with a collagen I hydrogel. Results of a prospective multicenter study]. / Rekonstruktion von Gelenkknorpeldefekten mit einem Kollagen-I-Hydrogel. Ergebnisse einer prospektiven Multicenterstudie.

STUDY GOALS: The aim of the study was to evaluate the therapeutic benefit of CaReS®, a type I collagen hydrogel-based autologous chondrocyte implantation technique, for the treatment of osteochondral defects of the knee (Outerbridge grades III and IV) within a prospective multicenter study. MATERIAL AND METHODS: A total of 116 patients in 9 clinical centers were treated with CaReS between 2003 and 2008. The Cartilage Injury Evaluation Package 2000 of the International Cartilage Repair Society (ICRS) was employed for data acquisition and included the subjective International Knee Documentation Committee score (IKDC score), the pain level (visual analog scale, VAS), the physical and mental SF-36 score, the overall treatment satisfaction and the functional IKDC status of the indexed knee. Follow-up evaluation was performed 3, 6 and 12 months after surgery and annually thereafter. RESULTS: The mean defect size treated was 5.4 ± 2.7 cm(2) with 30% of the cartilage defects being ≤4 cm(2) and 70% ≥4 cm(2). The mean follow-up period was 30.2 ± 17.4 months (minimum 12 months and maximum 60 months). The mean IKDC score significantly improved from 42.4 ± 13.8 preoperatively to 70.5 ± 18.7 (p < 0.01) in the mean follow-up period. Global pain level significantly decreased (p < 0.001) from 6.7 ± 2.2 preoperatively to 3.2 ± 3.1 at the latest follow-up. Both the physical and mental components of the SF-36 score significantly increased. At the latest follow-up 80% of the patients rated the overall treatment satisfaction as either good or very good. The functional IKDC knee status clearly improved from preoperative to the latest follow-up when 23.4% of the patients reported having no restriction of knee function (I), 56.3% had mild restriction (II), 17,2% had moderate restriction (III) and 3.1% revealed severe restriction (IV). CONCLUSIONS: The CaReS technique is a clinically effective and safe method for the reconstruction of isolated osteochondral defects of the knee joint and reveals promising clinical outcome up to 5 years after surgery. A longer follow-up period and larger patient cohorts are needed to evaluate the sustainability of CaReS treatment.

A novel rat tail collagen type-I gel for the cultivation of human articular chondrocytes in low cell density.

Collagen type-I matrix systems have gained growing importance as a cartilage repair device. However, most of the established matrix systems use collagen type-I of bovine origin seeded in high cell densities. Here we present a novel collagen type-I gel system made of rat tail collagen for the cultivation of human chondrocytes in low cell densities. Rat tail collagen type-I gel (CaReS, Arthro Kinetics, Esslingen, Germany) was seeded with human passage 2 chondrocytes in different cell densities to evaluate the optimal cell number. In vitro, the proliferation factor of low density cultures was more than threefold higher compared with high density cultures. After 6 weeks of in vitro cultivation, freshly prepared chondrocytes with an initial cell density of 2x10(5) cells/mL showed a proliferation factor of 33. A cell density of 2x10(5) cells/mL was chosen for in vitro and in vivo cultivation using the common nude mouse model as an in vivo system. Chondrocytes stayed viable as a Live/Dead fluorescence assay and TUNEL staining revealed. During in vitro cultivation, passage 0 cells partly dedifferentiated morphologically. In vivo, passage 0 cells maintained the chondrocyte phenotype and demonstrated an increased synthesis of collagen type-II protein and gene expression compared to passage 2 cells. Passage 2 cells did not redifferentiate in vivo. Cultivating a cell-seeded collagen gel of bovine origin as a control (AtelocollagenTM, Koken, Tokyo, Japan) did not lead to superior results with regard to cell morphology, col-II protein production and col-II gene expression. With the CaReS collagen gel system the best quality of repair tissue was obtained by seeding freshly isolated chondrocytes.

In vivo cultivation of human articular chondrocytes in a nude mouse-based contained defect organ culture model.

The nude mouse model is an established method to cultivate and investigate tissue engineered cartilage analogues under in vivo conditions. One limitation of this common approach is the lack of appropriate surrounding articular tissues. Thus the bonding capacity of cartilage repair tissue cannot be evaluated. Widely applied surgical techniques in cartilage repair such as conventional and three-dimensional autologous chondrocyte implantation (ACI) based on a collagen gel matrix cannot be included into nude mouse studies, since their application require a contained defect. The aim of this study is to apply an organ culture defect model for the in vivo cultivation of different cell-matrix-constructs. Cartilage defects were created on osteochondral specimens which had been harvested from 10 human knee joints during total knee replacement. Autologous chondrocytes were isolated from the cartilage samples and cultivated in monolayer until passage 2. On each osteochondral block defects were treated either by conventional ACI or a collagen gel seeded with autologous chondrocytes, including a defect left empty as a control. The samples were implanted into the subcutaneous pouches of nude mice and cultivated for six weeks. After retrieval, the specimens were examined histologically, immunohistochemically and by cell morphology quantification. In both, ACI and collagen gel based defect treatment, a repair tissue was formed, which filled the defect and bonded to the adjacent tissues. The repair tissue was immature with low production of collagen type II. In both groups redifferentiation of chondrocytes remained incomplete. Different appearances of interface zones between the repair tissue and the adjacent cartilage were found. The presented contained defect organ culture model offers the possibility to directly compare different types of clinically applied biologic cartilage repair techniques using human articular tissues in a nude mouse model.

[Liver laceration following a kick in a soccer game]. / Leberruptur nach einem Fusstritt im Fussballspiel.

Severe intraabdominal injuries in soccer are very rare. We present the case of an 18 year old soccer player who suffered from a grad IV liver laceration following a kick during a soccer game. After primary explorative laparatomy and liver packing in a hospital nearby the patient was transferred to our clinic. Following CT scan the injury was treated by suture of liver parencym lacerations, argon laser coagulation and pile duct repair. In soccer severe intraabdominal injuries should be expected following players collision at high velocity or kicking with the foot or the knee.

[The injury pattern following the introduction of the junior premier league in Germany compared to professional senior football (soccer)]. / Das Verletzungsmuster nach Einführung der A-Junioren-Fussball-Bundesliga in Deutschland im Vergleich zum Senioren-Profi-Fussball.

In 2003 the junior soccer premier league (U19) has been introduced in Germany to increase the competitive level in this group of age (16 - 18 years). It is the aim of this study to compare the injury pattern accompanying this new league of semi-professional junior soccer with a professional senior team. In a retrospective study all traumatic and overuse injuries, responsible for absence from practice or matches, which occurred in two seasons of one junior premier league team were recorded and analyzed. These data were compared to the injury pattern of a professional senior team based on a one-season survey. Overall, more traumatic than overuse injuries were seen. The lower extremity was predominantly affected by both. The ankle joint was the most injured joint. An injury rate of 2.89 per 1000 hours of soccer was calculated for the juniors and 2.35 for the seniors. Junior players missed 15.8 days and seniors 17.1 days of practice or match as result of an injury. Semi-professional junior and professional senior soccer share the same injury patterns with regard to injury rates and types of injuries. Therefore a professional medical care with special emphasis on prophylaxis is warranted in semi-professional junior soccer.

Autologous chondrocyte implantation (ACI) for cartilage defects of the knee: A guideline by the working group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Trauma (DGOU).

BACKGROUND: Autologous chondrocyte implantation (ACI) is an established and well-accepted procedure for the treatment of localised full-thickness cartilage defects of the knee. METHODS: The present review of the working group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Trauma (DGOU) describes the biology and function of healthy articular cartilage, the present state of knowledge concerning therapeutic consequences of primary cartilage lesions and the suitable indication for ACI. RESULTS: Based on best available scientific evidence, an indication for ACI is given for symptomatic cartilage defects starting from defect sizes of more than three to four square centimetres; in the case of young and active sports patients at 2.5cm(2), while advanced degenerative joint disease needs to be considered as the most important contraindication. CONCLUSION: The present review gives a concise overview on important scientific background and the results of clinical studies and discusses the advantages and disadvantages of ACI. LEVEL OF EVIDENCE: Non-systematic Review.

[Metaphyseal fitting short-stem prosthesis - preliminary results of a prospective single-surgeon series]. / Metaphysär verankernde, zementfreie Kurzschaftprothese - klinisch-radiologische Ergebnisse einer prospektiven Single-Surgeon-Studie.

BACKGROUND: Conventional uncemented femoral stems provide good long-term fixation in patients with a wide range of clinical function. However, preservation of bone stock, and minimally invasive approaches have led to exploration into various other implant designs. Short-stem prosthesis focusing on a stable metaphyseal fit have emerged to address these challenges in total hip arthroplasty. The purpose of this study was to evaluate the clinical and radiological results of a newly developed short-stem hip prosthesis AIDA® in context of a single surgeon study. MATERIAL AND METHODS: From February 2009 to December 2013, 72 cementless "AIDA® short stems" (Fa. Implantcast) were implanted by a single surgeon in one study centre via the Watson Jones interval. All patients signed informed consent prior to screening and the study design was approved by the local ethics committee. 51 patients with 52 implants (35 female, 36 male) with a follow-up > 24 months were included in this prospective, controlled clinical trial. The patients were pre- and postoperatively examined clinically and radiological by a specified protocol. RESULTS: The average patient age at the time of THA was 61 ± 3.2 years (min.-max. 46-68 years). At the last follow-up, the average Harris Hip score increased from 41.4 ± 4.5 preoperatively to 96.8 ± 3.2 points postoperatively. The hospital stay was 9.1 days on average. The X-rays showed in all cases a stable fixation of the stems with full bony integration and no signs of loosening or migration. There were no specific complications relating to the less invasive approach. Postoperatively one periprosthetic fracture was evident. The revision operation into a cementless stem was done without any complications (revisions rate 1.9 %). CONCLUSION: The newly developed "AIDA short stem" is a promising hip implant for the young and active patient with osteoarthritis of the hip. The short-term results are encouraging, but nevertheless mid- and long-term results must be further observed on a prospective basis as part of this collective study.

[Dihydrotestosterone improves the osseointegration of cobalt-chromium implants]. / Dihydrotestosteron verbessert die knöcherne Einheilung von Kobalt-Chrom-Implantaten.

BACKGROUND: The osseointegration of actually rarely implanted cobalt-chromium implants can be critical in an elderly population. The aim of our study was to evaluate the effect of preoperative testosterone treatment on the osseointegration of cobalt-chromium implants. MATERIALS AND METHODS: Press-fit implantation of 1.6 mm-diameter cobalt-chromium-molybdenum (CoCrMo) implants was performed in rats without pre-treatment in one group (n = 10) and after pre-treatment with 1 mg dihydrotestosterone (DHT) 2 days before surgery in the other group (n = 10). After 14 days, the specimens were examined by a pull-out test, histology and histomorphometry. RESULTS: The biomechanical testing delivered inconsistent data leading to no significant difference (6.45 ± 6.94 N vs. 4.66 ± 3.77 N). Histology showed closed contact between surrounding tissue and the implants in both groups. The bone/implant contact area was significantly enhanced after treatment with DHT (42.23 % ± 9.25 vs. 57.57 % ± 16.71, p < 0.05), while the ratio of osteoid was reduced (38.68 % ± 16.7 vs. 27.38 % ± 13.02, not significant). CONCLUSIONS: Pre-treatment with DHT enhances osseointegration of cobalt-chromium implants through enhanced mineralisation of peri-implant tissue. The treatment might additionally shorten postoperative rehabilitation due to its positive effects on musculature.

[Autologous chondrocyte implantation (ACI) for cartilage defects of the knee: a guideline by the working group "Tissue Regeneration" of the German Society of Orthopaedic Surgery and Traumatology (DGOU)]. / Stellenwert der autologen Chondrozytentransplantation (ACT) in der Behandlung von Knorpelschäden des Kniegelenks - Empfehlungen der AG Klinische Geweberegeneration der DGOU.

Autologous chondrocyte transplantation/implantation (ACT/ACI) is an established and recognised procedure for the treatment of localised full-thickness cartilage defects of the knee. The present review of the working group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Traumatology (DGOU) describes the biology and function of healthy articular cartilage, the present state of knowledge concerning potential consequences of primary cartilage lesions and the suitable indication for ACI. Based on current evidence, an indication for ACI is given for symptomatic cartilage defects starting from defect sizes of more than 3-4 cm2; in the case of young and active sports patients at 2.5 cm2. Advanced degenerative joint disease is the single most important contraindication. The review gives a concise overview on important scientific background, the results of clinical studies and discusses advantages and disadvantages of ACI.

[Tissue engineering of cartilage replacement material - mechanical stimulation in the in-vitro cultivation of human chondrocytes]. / Tissue Engineering von Knorpelersatzgewebe - Mechanische Stimulation in der In-vitro-Kultivierung von humanen Chondrozyten.

The treatment of cartilage defects remains a major problem in orthopaedics. With regard to cartilage tissue engineering, the reimplantation of pre-cultivated chondrocytes in the form of a chondrocyte graft is a promising alternative to conventional methods. Clinical practice requires this MACT procedure (matrix-associated autologous chondrocyte transplantation) to produce a biocompatible replacement tissue with adequate mechanical properties. Mechanical stimulation has the capacity to improve the quality of these cell-seeded biomaterials. By altering chondrocytes' cellular activities, the biological and biomechanical properties of cartilage replacement tissue can be modulated. Different systems are used for this purpose, e.g. shear, perfusion, hydrostatic pressure or compression. The mechanisms, biological effects, chances and problems of the techniques are presented and assessed. Among the stimulating techniques considered are systems that apply indirect and direct shear forces such as spinner flasks, rotating-wall bioreactors, direct tissue shear and perfusion culture systems. The application of hydrostatic pressure or compression may be brought about by either static or dynamic loading systems. Compressive loading is considered in the light of both its short- and long-term effects; additionally two exemplified systems are discussed in detail. However, despite promising approaches and seemingly favourable tissue characteristics, the in vitro culturing of functional cartilage replacement tissue with cartilage-like mechanical and biological characteristics still remains elusive. Furthermore, controlling, monitoring and regulating culturing conditions are general biotechnological requirements of a standardised in vitro cultivation. Among these, different aspects such as aseptic operation, media supplementation, nutrient and gas exchange, temperature and humidity control are considered.

[Comparison of trunk muscle strength of soccer players with and without low back pain]. / Vergleich der Rumpfmuskelkraft von Fussballspielern mit und ohne Rückenschmerzen.

AIM OF THE STUDY: Low back pain in soccer players is one of the frequently appearing disorders caused by overuse. Myogenic dysbalances are under discussion as possible reason for this problem. In the present study the muscular strength profile of the trunk musculature of soccer players with and without low back pain was evaluated. The results of the asymptomatic players were compared to those of players with low back pain; furthermore, the collected data were compared to those of an asymptomatic reference group. The question posed was whether soccer players show a specific strength profile caused by the special, sports-specific requirements and whether this strength profile differs between players with and without low back pain. METHOD: In the present study the isometric maximal strength of 18 soccer players with and 18 soccer players without low back pain was measured in all 3 planes. The reference group was provided by the Proxomed company, which had previously analysed 1045 healthy untrained individuals of various age groups. RESULTS: The soccer players showed a sport-specific profile for the musculature, which was determined by a significant reduction of the flexion and rotation strength (flex: Ø 5.21 N/kg vs. Ø 6.49 N/kg; Ø 5.78 N/kg vs. Ø 6.66 N/kg respectively; rotation: left 7.09 N/kg, right 8.69 N/kg vs. left/right 10.1 N/kg; left 7.22 N/kg, right 8.24 N/kg vs. left/right 10.0 N/kg, respectively) as well as by an increased lateral flexion strength to the right-hand side in comparison to the reference group (lat. flex. right: 9.87 N/kg, respectively, 10.67 N/kg vs. 8.3 N/kg). A statistically significant correlation between the muscular activity in the trunk stability of soccer players with and without low back pain could not be shown. CONCLUSION: Obviously sports-specific training with additional specific training of the trunk muscles is not sufficient for the development of a balanced strength of trunk musculature. In the present study an influence of the performance of the trunk musculature on the incidence of low back pain could not be shown.

[Procalcitonin (PCT) as diagnostic tool for the monitoring of spondylodiscitis]. / Procalcitonin (PCT) als Verlaufsparameter der Spondylodiszitis.

AIM: The diagnosis of spondylodiscitis is often prolonged, but it is an important differential diagnosis of backache. The discrimination between a bacterial infection and an aseptic inflammation with laboratory examinations like ESG, CRP or leukocytes is not possible. The aim of the present study was to determine the value of procalcitonin (PCT) as a diagnostic tool and monitoring parameter for spondylodiscitis and for the discrimination between bacterial infection and aseptic inflammation of the spine. METHOD: A total of 17 patients with spondylodiscitis and 18 patients with disc herniation as control were included in this study and ESG, CRP, leukocytes, fibrinogen, PNM elastase und PCT were examined for 50 days. The median age was 65 (17-78) years and the ratio of males to females was 8 : 9 in patients with spondylodiscitis and 62 (32-87) years and 7 : 11 in patients with disc herniation. For microbiological examination, CT-guided punctures were performed in patients with spondylodiscitis. RESULTS: In 64 % of the 17 patients with spondylodiscitis a microbiological agent was detected, in 73 % of these cases staphylococcus aureus was isolated. The laboratory parameters indicating an infection were increased except for two cases in patients with spondylodiscitis, the mean value of CRP was 115 mg/dL. Influenced by the therapy these parameters decreased during the observation period. Except for one patient with an infection of a cardiac pacemaker, the PCT concentration was not elevated in both groups (< 0.5 ng/mL). In the group with disc herniation there were no elevated laboratory parameters during the entire observation period. CONCLUSION: PCT is not useful as diagnostic tool or monitoring parameter for spondylodiscitis. Furthermore, it is not useful for the discrimination between a bacterial infection and an aseptic inflammation of the spine.

[Comparison of the treatment of slipped capital femoral epiphysis with K-wires and cannulated titanium screws]. / Vergleich der Therapie der Epiphyseolysis capitis femoris mit Kirschner-Drähten und kanülierten Titanschrauben.

AIM: The treatment of slipped capital femoral epiphysis (SCFE) is usually treated operatively, but there is still no consensus about the method to be used. Up to a 30 degrees degree of slipping, the epiphysis is normally fixed in situ. The aim of our study was to compare the intermediate results after fixation in situ by K-wires versus cannulated titanium screws (Königsee-Implantate, Königsee-Aschau, Germany). METHODS: In this study 46 patients with SCFE grade I and II and mostly chronic slipping of the epiphysis were included. After fixation in situ and, if necessary, careful, closed reposition, the patients were clinically and radiologically followed-up for one year. The clinical results were documented by the score adapted from Heyman and Herndon. Furthermore, MRI scans were done to evaluate the vitality of the epiphysis pre- and postoperatively, when titanium screws were used. RESULTS: Clinical follow-up showed comparable results in the clinical scores after fixation by K-wires or cannulated titanium screws (3.13 +/- 1.02 vs. 3.10 +/- 1.01). After the treatment with titanium screws we saw a higher rate of abnormal gait (33.3 % vs. 19 %), a decreased rate of the positive Drehmann sign (10 % vs. 38 %) and a lower rate of revisions (16 % vs. 50 %) in comparison to K-wire fixation. After displacement of the K-wires we saw chondrolysis and prearthrosis in one case. Removal of the K-wires was done without any complications, while the removal of the cannulated titanium screws failed in 4 of 10 cases. CONCLUSION: The treatment of SCFE with K-wires and cannulated titanium screws showed comparable results in the clinical follow-up. The treatment with cannulated titanium screws reduces the number of necessary revisions, but the removal of the material is hindered. Because of the lower rate of complications we prefer in the meantime the use of cannulated steel screws.

[Surface pretreatment of endoprostheses by silica/silane to optimise the hydrolytic stability between bone cement and metal. Total hip and knee arthroplasty]. / Silikatisierte/silanisierte Implantatoberflächen zur optimierten hydrolysestabilen Verbundfestigkeit zwischen Knochenzement und Metall. Zementierte Hüft- und Knieendoprothetik.

BACKGROUND: The aseptic loosening of cemented total hip and knee arthroplasties is still an unsolved problem. In this regard, the hydrolytic resistance in the metal-to-bone cement interface is of major importance. METHODS: Cemented pretreated femur stems and tibia components coated by means of a silica/silane interlayer system were dynamically loaded with the help of a hip and knee simulator similar to DIN ISO Norm. After loading, the components were microscopically analysed concerning both debonding in the metal-to-bone cement interface and cement mantle defects. These data were matched with uncoated components. Unloaded coated and uncoated femur and tibia components acted as controls. RESULTS: Compared with uncoated components, the pretreated and coated ones yielded a significant reduction in cement defects as well as of debonding in the metal-to-bone cement interface. CONCLUSION: Using the silica/silane interlayer system for cemented femur and tibia components, hydrolytic debonding in the metal-to-bone cement interface with following cement mantle failure can be reduced. This could help increase the long-term stability of the metal-to-bone cement compound, with decreased aseptic loosening.

[Therapy effects of testosterone on the recovery of bone defects]. / Therapieeffekte von Testosteron auf die Heilung von Knochendefekten.

AIM: Androgens have proliferative effects on osteoblasts and increase fracture healing by systemic and local stimulation of bone formation. The aim of the present study was to evaluate if the systemic stimulation by androgens leads to increased bone-defect healing. METHODS: 1.5-mm trepanation defects were created in the femoral diaphysis of 30 Sprague-Dawley rats. 10 animals were used as untreated controls and 10 animals per group were treated by intramuscular injection of 1 or 10 mg dihydrotestosterone two days prior to surgery. After 14 days the samples were explanted and examined by macroscopy, histology and histomorphometry. RESULTS: All animals were included into the study and were analysed. Clinical observation showed no complications. Macroscopic examination and histology showed no significant differences. All defects were filled with trabecular bone in direct contact to the surrounding bone. Histomorphometry showed a significantly decreased bone content in the controls in comparison to both therapy groups, while the therapy groups showed no significant differences between each other. CONCLUSION: The stimulation of healing of bone defects with androgens leads to a significantly higher bone content inside the defects. In clinical application, androgens may be a possibility to increase bone formation, especially in elderly patients. Furthermore, it may be possible to shorten postoperative rehabilitation because of the effects of androgens on muscles.

[Mechanical bending strength of explanted ex vivo bone cements compared with in vitro samples]. / Mechanische Biegefestigkeiten von explantierten Ex-vivo-Knochenzementen verglichen mit In-vitro-Proben.

INTRODUCTION: The mechanical properties of acrylic bone cements are an important factor in determining an efficient load transmission between prosthesis and bone to guarantee the long-term stability in cemented hip arthroplasty. MATERIAL AND METHODS: Palacos and Refobacin Palacos specimens from 21 aseptically loosened femoral compoments of cemented hip arthroplasties manufactured by the first to third generation cementing technique have been mechanically tested in a standardised four-point bending test (ISO 5833). In vitro manufactured Palacos and Refobacin Palacos specimens served as a control group. The fatigue fracture surfaces were morphologically analysed with light microscopy. RESULTS: Under in vitro conditions manufactured specimens had higher values of bending strength, with the exception of blood contaminated ones, compared to ex vivo specimens. Ex vivo specimens of the second and third generation cementing technique had higher values than specimens of the first generation. CONCLUSIONS: Acrylic bone cements are subjected to a multifactorial material fatigue in vivo. Here, the art and quality of cementing technique is of eminent importance in determining the long-term stability of cemented hip arthroplasty.

[Optical coherence tomography (OCT) to evaluate cartilage tissue engineering]. / Die optische Kohärenztomografie (OCT) zur Darstellung der Regenerateigenschaften im Tissue Engineering von Knorpelgewebe.

AIM: The aim of this study was to investigate hyaline cartilage defects treated with cell-seeded artificial matrix systems (two different collagen type I gels) with the method of optical coherence tomography (OCT) and to correlate the results with conventional histological and immunocytochemical staining. METHOD: Osteochondral blocks were harvested from 20 patients undergoing total knee replacement and trimmed to 2 x 2 cm. Under sterile conditions, chondral defects of 8 mm diameter were either filled with a collagen type I gel plug seeded with autologous chondrocytes (2 x 10 (5)/mL gel), or with a corresponding gel plug which was stabilised by a 20-fold compression. Of each group, 5 specimens were cultivated for 6 weeks under standardised in vitro conditions (37 degrees C, 5 % CO (2), humidified atmosphere), while the remaining 5 specimens were implanted subcutaneously in nude mice (BALBc -/-). Immediately after recovery, the repair tissue and bonding zones were investigated by OCT. Subsequently, specimens were decalcified and investigated by H&E staining and collagen type II immunostaining. The results of OCT and conventional staining were correlated. RESULTS: By OCT, repair tissue could be investigated up to 1.6 mm in depth, physically limited by the utilised OCT system. In the denser hyaline cartilage regions, OCT resolution was reduced. Regardless of cultivation (in vitro or nude mouse), ultrastructural features of the repair tissue could be demonstrated. In particular, ultrastructural differences between the two investigated collagen gels could be detected. Moreover, the bonding region between repair tissue and hyaline cartilage could be evaluated by OCT investigation. The results of the OCT measurements were confirmed by H&E and collagen type II immunostaining. CONCLUSION: By OCT, repair tissue generated by the treatment of cartilage defects with tissue-engineered matrix systems could be evaluated in vitro. Future studies may show if repair tissue quality may be monitored in situ by OCT.

[Clinical results after three years use of matrix-associated ACT for the treatment of osteochondral defects of the knee]. / Klinische Drei-Jahres-Ergebnisse der matrixgekoppelten ACT zur Behandlung osteochondraler Defekte am Kniegelenk.

AIM: The aim of this study was to examine the clinical results after the treatment of osteochondral defects of the knee with autologous bone grafting and matrix-supported autologous chondrocyte transplantation (ACT). METHOD: In this study 13 patients with osteochondral defects of the knee (12 femoral, 1 tibial) with OCD ICRS grade IV or ICRS grade IV B were included. The osteochondral defects were reconstructed simultaneously with autologous monocortical cancellous bone cylinders or chips from cancellous bone and matrix-supported autologous chondrocyte transplantation (CaReS). Data were analysed in accordance with the ICRS criteria and the Brittberg score. Patients were followed up to 36 months after the operation. RESULTS: The average age of the patients was 34.9 (16 - 47) years at the time of surgery. The size of the defect was 8.1 (3.8 - 13.5) cm(2). The subjective and objective IKDC scores, the Brittberg and the ICRS function score were statistically significantly improved during the observation time. In one patient the transplantation failed and another patient was not available for the follow-up at 36 months. The objective IKDC score and the ICRS function score increased from 0/13 (0 %) to 11/12 (91.7 %) in categories A and B, or I and II, respectively, after 3 years. At this point of time 83.4 % (10/12) of the patients voted the treatment as excellent or good. The subjective IKDC score improved from 38.4 (+/- 12.7) preoperatively to 66.1 (+/- 17.0) after 3 years. CONCLUSION: The treatment of osteochondral defects of the knee with autologous bone grafting and matrix-supported autologous chondrocyte transplantation shows promising results even for larger defects. But for a final decision about this therapy the present sample size was too small. There is a need for further long-term investigation with a larger number of patients.

Improvement of the long-term adhesive strength between bone cement and bone in cemented cup arthroplasty: ex-vivo study.

INTRODUCTION: One of the main causes of cup loosening in cemented total hip replacement is the lack of a hydrolysis stable compound between the hydrophobic bone cement and the hydrophilic acetabular bone stock. Thus, the long-term adhesive strength between bone and bone cement is decreased resulting in premature aseptic loosening. Accordingly, an amphiphilic bonding system was developed to prevent hydrolytic debonding in the interface bone-to-bone cement. MATERIALS AND METHODS: Polyethylene cups were cemented in cadaver sheep hips. The hips were prepared with (n = 10) a multilayer bonding system as well as with an improved monolayer bonding system with (n = 10) and without (n = 10) UV-light hardening. The hips were dynamically loaded (10(6) cycles; 3 Hz; upper/lower load 1,500/200 N) and afterwards turned out with a defined strength to determine the interface compound strength. Dynamically loaded cemented cups without using the bonding system (n = 10) function as a control group. RESULTS: The interface adhesive strength improved significantly by a factor of 1.9 (using the multilayer bonding system) compared to the unconditioned ones (P < or = 0.05); for the monolayer bonding system without (with) UV-light hardening the compound strength was 11.9-fold (> or =22.2-fold) higher (P < or = 0.001). CONCLUSION: The bonding system significantly improves the adhesive strength between bone and bone cement in cemented cup arthroplasty.