Empfehlungen der AG Klinische Geweberegeneration zur Behandlung von Knorpelschäden am Kniegelenk

The Working Group of the German Orthopedic and Trauma Society (DGOU) on Tissue Regeneration has published recommendations on the indication of different surgical approaches for treatment of full-thickness cartilage defects in the knee joint in 2004, 2013 and 2016. Based upon new scientific knowledge and new developments, this recommendation is an update based upon the best clinical evidence available. In addition to prospective randomised controlled clinical trials, this also includes studies with a lower level of evidence. In the absence of evidence, the decision is based on a consensus process within the members of the working group.The principle of making decision dependent on defect size has not been changed in the new recommendation either. The indication for arthroscopic microfracturing has been reduced up to a defect size of 2 cm² maximum, while autologous chondrocyte implantation is the method of choice for larger cartilage defects. Additionally, matrix-augmented bone marrow stimulation (mBMS) has been included in the recommendation for defects ranging from 1 to 4.5 cm². For the treatment of smaller osteochondral defects, in addition to osteochondral transplantation (OCT), mBMS is also recommended. For larger defects, matrix-augmented autologous chondrocyte implantation (mACI/mACT) in combination with augmentation of the subchondral bone is recommended.

Chondrocyte Isolation from Loose Bodies-An Option for Reducing Donor Site Morbidity for Autologous Chondrocyte Implantation

Loose bodies (LBs) from patients with osteochondritis dissecans (OCD) are usually removed and discarded during surgical treatment of the defect. In this study, we address the question of whether these LBs contain sufficient viable and functional chondrocytes that could serve as a source for autologous chondrocyte implantation (ACI) and how the required prolonged in vitro expansion affects their phenotype. Chondrocytes were isolated from LBs of 18 patients and compared with control chondrocyte from non-weight-bearing joint regions (n = 7) and bone marrow mesenchymal stromal cells (BMSCs, n = 6) obtained during primary arthroplasty. No significant differences in the initial cell yield per isolation and the expression of the chondrocyte progenitor cell markers CD44 + /CD146+ were found between chondrocyte populations from LBs (LB-CH) and control patients (Ctrl-CH). During long-term expansion, LB-CH exhibited comparable viability and proliferation rates to control cells and no ultimate cell cycle arrest was observed within 12 passages respectively 15.3 ± 1.1 mean cumulative populations doublings (CPD). The chondrogenic differentiation potential was comparable between LB-CH and Ctrl-CH, but both groups showed a significantly higher ability to form a hyaline cartilage matrix in vitro than BMSC. Our data suggest that LBs are a promising cell source for obtaining qualitatively and quantitatively suitable chondrocytes for therapeutic applications, thereby circumventing donor site morbidity as a consequence of the biopsies required for the current ACI procedure.

Long-term cost-effectiveness of matrix-associated chondrocyte implantation in the German health care system: a discrete event simulation

INTRODUCTION

Cartilage defects in the knee can be caused by injury, various types of arthritis, or degeneration. As a long-term consequence of cartilage defects, osteoarthritis can develop over time, often leading to the need for a total knee replacement (TKR). The treatment alternatives of chondral defects include, among others, microfracture, and matrix-associated autologous chondrocyte implantation (M-ACI). The purpose of this study was to determine cost-effectiveness of M-ACI in Germany with available mid- and long-term outcome data, with special focus on the avoidance of TKR.

MATERIALS AND METHODS

We developed a discrete-event simulation (DES) that follows up individuals with cartilage defects of the knee over their lifetimes. The DES was conducted with a status-quo scenario in which M-ACI is available and a comparison scenario with no M-ACI available. The model included 10,000 patients with articular cartilage defects. We assumed Weibull distributions for short- and long-term effects for implant failures. Model outcomes were costs, number of TKRs, and quality-adjusted life years (QALYs). All analyses were performed from the perspective of the German statutory health insurance.

RESULTS

The majority of patients was under 45 years old, with defect sizes between 2 and 7 cm² (mean: 4.5 cm²); average modeled lifetime was 48 years. In the scenario without M-ACI, 26.4% of patients required a TKR over their lifetime. In the M-ACI scenario, this was the case in only 5.5% of cases. Thus, in the modeled cohort of 10,000 patients, 2700 TKRs, including revisions, could be avoided. Patients treated with M-ACI experienced improved quality of life (22.53 vs. 21.21 QALYs) at higher treatment-related costs (18,589 vs. 14,134 € /patient) compared to those treated without M-ACI, yielding an incremental cost-effectiveness ratio (ICER) of 3376 € /QALY.

CONCLUSION

M-ACI is projected to be a highly cost-effective treatment for chondral defects of the knee in the German healthcare setting.

Sustained superiority in KOOS subscores after matrix-associated chondrocyte implantation using spheroids compared to microfracture

PURPOSE

To evaluate the safety and efficacy of matrix-associated autologous chondrocyte implantation (ACI) using spheroids in comparison to arthroscopic microfracture for the treatment of symptomatic cartilage defects of the knee.

METHODS

In a prospective multicenter-controlled trial, patients aged between 18 and 50 years, with single symptomatic focal cartilage defects between 1 and 4 cm² (mean 2.6 ± 0.8, median 2.75, range 1.44-5.00) in the knee were randomized to treatment with ACI with spheroids (n = 52) or microfracture (n = 50). Primary clinical outcome was assessed by the Knee Injury and Osteoarthritis Outcome Score (KOOS). Analyses were performed in a defined hierarchical manner where outcomes of ACI were first compared to baseline values followed by a comparison to the microfracture group with repeated-measures ANCOVA with a non-inferiority approach. Subgroup analyses were performed to investigate the influence of age and defect size on the overall KOOS. Secondary clinical outcomes were the magnetic resonance observation of cartilage repair tissue (MOCART), modified Lysholm score and International Knee Documentation Committee (IKDC) examination form. Safety data focused on adverse events. Here the 5 years results are presented at which there were 33 observed cases in the ACI group and 30 in the microfracture group.

RESULTS

The overall KOOS and its five subscores were significantly improved compared to baseline for both the ACI and microfracture group. Non-inferiority of ACI to microfracture was confirmed for the overall KOOS and the subscores, while for the subscores activities of daily living, quality of life and sports and recreation of the threshold for superiority was passed. In the ACI group, a notably more rapid initial improvement of the KOOS was found at three months for the older age group compared to the younger age group and the microfracture group. No other differences were found based on age or defect size. In addition, clinical improvement was found for the MOCART, modified Lysholm and IKDC examination form both the ACI and microfracture group. No safety concern related to either treatment was observed.

CONCLUSION

This study confirms the safety and efficacy of matrix-associated ACI with spheroids at a mid to long-term follow-up. Non-inferiority of ACI to microfracture was confirmed for the overall KOOS and all subscores, while superiority was reached for the subscores activities of daily living, quality of life and sports and recreation in the ACI group. This underlines the importance of ACI for the young and active patients.

LEVEL OF EVIDENCE

I.

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

Background:

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

Purpose:

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

Study Design:

Cohort study; Level of evidence, 2.

Methods:

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

Results:

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

Conclusion:

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

Registration:

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

Matrix-Associated Autologous Chondrocyte Implantation with Spheroid Technology Is Superior to Arthroscopic Microfracture at 36 Months Regarding Activities of Daily Living and Sporting Activities after Treatment

OBJECTIVE

Matrix-associated autologous chondrocyte implantation (ACI) and microfracture (MF) are well-established treatments for cartilage defects of the knee. However, high-level evidence comparing microfracture and spheroid technology ACI is limited.

DESIGN

Prospective, phase III clinical trial with patients randomized to ACI (N = 52) or MF (N = 50). Level of evidence: 1, randomized controlled trial. Both procedures followed standard protocols. For ACI 10 to 70 spheroids/cm² were administered. Primary outcome measure was the Knee Injury and Osteoarthritis Outcome Score (KOOS). This report presents results for 36 months after treatment.

RESULTS

Both ACI and MF showed significant improvement over the entire 3-year observation period. For the overall KOOS, noninferiority of ACI (the intended primary goal of the study) was formally confirmed; additionally, for the subscores "Activities of Daily Living" and "Sport and Recreation," superiority of ACI over MF was shown at descriptive level. Occurrence of adverse events were not different between both treatments (ACI 77%; MF 74%). Four patients in the MF group required reoperation which was defined as treatment failure. No treatment failure was reported for the ACI group.

CONCLUSIONS

Patients treated with matrix-associated ACI with spheroid technology showed substantial improvement in various clinical outcomes after 36 months. The advantages of ACI compared with microfracture was underlined by demonstrating noninferiority, in overall KOOS and superiority in the KOOS subscores "Activities of Daily Living" and "Sport and Recreation." In the present study, subgroups comparing different age groups and defect sizes showed comparable clinical outcomes.

Treatment Costs of Matrix-Associated Autologous Chondrocyte Implantation Compared With Microfracture: Results of a Matched-Pair Claims Data Analysis on the Treatment of Cartilage Knee Defects in Germany

BACKGROUND

Articular cartilage damage is caused by traumatic sport accidents or age-related degeneration and might lead to osteoarthritis, which represents a socioeconomic burden to society. Cartilage damage in the knee is commonly treated surgically with microfracture (MFX) or matrix-associated autologous chondrocyte implantation (MACI).

PURPOSE

To quantify the initial and follow-up costs associated with MFX and MACI treatments from the viewpoint of statutory health insurance in Germany.

STUDY DESIGN

Economic decision analysis; Level of evidence, 2.

METHODS

This comparative study was based on an anonymized representative claims data set of 4 million patients covered by statutory health insurance in Germany. Patients undergoing outpatient or inpatient treatment with MACI or MFX for cartilage damage in the knee between January 1, 2012, and December 31, 2013, were included and evaluated over 5 years. Groups (MACI and MFX) were adjusted via propensity score matching before initial treatment. The matched groups were compared regarding their outpatient, inpatient, pharmaceutical, and other costs during the 5-year period.

RESULTS

In total, 127 patients per group were analyzed (59.1% male, 40.9% female; mean age, 37 years). In the year of the initial surgical procedure, costs were €14,804.13 in the MACI group and €5458.59 in the MFX group. In years 2 and 3 after initial surgery, treatment costs were comparable between patients treated with MACI (€2897.97 and €2114.87, respectively) and MFX (€2842.66 and €1967.42, respectively), with slightly higher treatment costs for those treated with MACI. In years 4 and 5 after surgery, costs were less in patients treated with MACI (€2154.79 and €1478.08, respectively) than in those treated with MFX (€2232.57 and €2061.63, respectively). Costs related to revision surgery were, on average, €3732 for MACI and €3765 for MFX. Thus, additional costs in years with revision surgery were €1672 for MACI and €1915 for MFX.

CONCLUSION

This was the first study to analyze a large representative population claims database with propensity score matching, and results indicated that follow-up costs of patients treated with MACI and MFX began to converge over time. We found that total costs for MACI were higher than for MFX but that additional costs for MACI were lower than previously reported. Perceived morbidity may have little to do with cost.

Matrix-Associated Chondrocyte Implantation Is Associated With Fewer Reoperations Than Microfracture: Results of a Population-Representative, Matched-Pair Claims Data Analysis for Cartilage Defects of the Knee

Background:

Symptomatic cartilage defects of the knee are commonly surgically treated by microfracture (MFX) or matrix-associated chondrocyte implantation (M-ACI). Several randomized controlled trials have compared MFX and M-ACI, showing a tendency to lower reoperation rates for M-ACI, but results vary widely between studies.

Purpose:

To compare reoperation rates after MFX and M-ACI in cartilage defects of the knee outside clinical trials in a representative sample of the population.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

This study was based on anonymized, population-representative claims data of 4 million insured persons in Germany. Patients who underwent MFX or M-ACI for cartilage defects of the knee with a follow-up of 2 years were compared. The primary endpoint was the need for a reoperation, defined as a claim for a second surgical procedure from the same patient at the knee joint (27 procedure codes), meniscus and cartilage (35 procedure codes), or patella (102 procedure codes) or the need for knee replacement (11 procedure codes). Group comparisons were performed using log-rank tests, with a 2-sided P value of <.05 to indicate significance. For adjusted analysis, propensity score matching was applied. Age, sex, comedications, and comorbidities were used as matching parameters.

Results:

A total of 6425 patients fulfilled the inclusion criteria: 6273 treated with MFX and 152 treated with M-ACI (mean age, 53 and 36 years, respectively). In the 2 years after treatment, 1271 patients in the MFX group needed a reoperation compared with 19 in the M-ACI group (20.3% vs 12.5%, respectively; P = .0199). For adjusted analysis after propensity score matching, 127 patients per group were analyzed. Their mean age was 37 years. At the end of the second follow-up year, 28 and 16 patients needed reoperations in the MFX and M-ACI groups, respectively (22.0% vs 12.6%, respectively; P = .0498).

Conclusion:

This study used a representative sample of the population and a broad definition of a reoperation, thus expanding evidence from clinical trials. We found a significant advantage of M-ACI in reoperation rates 2 years after treatment. After adjusting for age, sex, comedications, and comorbidities, M-ACI still showed significantly lower reoperation rates after 2 years.

Matrix-Associated Autologous Chondrocyte Implantation Is an Effective Treatment at Midterm Follow-up in Adolescents and Young Adults

Background

Autologous chondrocyte implantation (ACI) is an established method for treating cartilage defects in the knee of adult patients. However, less is known about its effectiveness in adolescents.

Hypothesis

Third-generation matrix-associated ACI (MACI) using spheroids (co.don chondrosphere/Spherox) is an effective and safe treatment for articular cartilage defects in adolescents aged 15 to 17 years, with outcomes comparable with those for young adults aged 18 to 34 years.

Study Design

Cohort study; Level of evidence, 3.

Methods

A total of 71 patients (29 adolescents, 42 young adults) who had undergone ACI using spheroids were evaluated retrospectively in this multicenter study. For adolescents, the mean defect size was 4.6 ± 2.4 cm², and the follow-up range was 3.5 to 8.0 years (mean, 63.3 months). For young adults, the mean defect size was 4.7 ± 1.2 cm², and the follow-up range was 3.8 to 4.3 years (mean, 48.4 months). At the follow-up assessment, outcomes were assessed by using validated questionnaires (Knee injury and Osteoarthritis Outcome Score [KOOS], International Knee Documentation Committee [IKDC] subjective knee evaluation form and current health assessment form, and modified Lysholm score), the magnetic resonance observation of cartilage repair tissue (MOCART) score, and if relevant, time to treatment failure. Safety was assessed by the treatment failure rate.

Results

No significant difference between the 2 study groups was found for KOOS, IKDC, or MOCART scores, with all patients achieving high functional values. A significant difference was found in the modified Lysholm score, favoring the young adult group over the adolescent group (22.3 ± 1.9 vs 21.0 ± 2.4, respectively; P = .0123). There were no differences between the rates of treatment failure, with 3% in the adolescent group and 5% in the young adult group.

Conclusion

Third-generation MACI using spheroids is a safe and effective treatment for large cartilage defects of the knee in adolescents at midterm follow-up. Outcomes are comparable with those for young adults after ACI.

Treatment of osteochondral defects with a combination of bone grafting and AMIC technique

INTRODUCTION

Osteochondral defects of the knee may cause functional impairment of young and sportively active patients. Different surgical treatment options have been proposed using either one or two step procedures. The aim of the current study was to evaluate mid-term outcomes of combined bone grafting with autologous matrix-associated chondrogenesis (AMIC) for the treatment of large osteochondral defects.

MATERIALS AND METHODS

15 Patients with osteochondrosis dissecans of the medial femoral condyle grade III or IV according to ICRS classification were treated with a single step surgical procedure combining bone grafting and the AMIC procedure. Mean defect size was 4.98 cm² (± 3.02) and patients were examined at 6, 12 weeks, 6 and 12 month and at mean final follow-up of 49 months (36-61). Patients were evaluated using VAS, IKDC, KOOS, Lysholm, Tegner activity scores and psychological and physical health assessed using the SF 12. MRI evaluation was performed at final follow-up using the MOCART score.

RESULTS

Pain had significantly decreased at final follow-up (7.2 ± 1.4 vs. 2.4 ± 2.6) compared to preoperative baseline. All functional scores had improved significantly throughout the follow-up period (IKDC from 36.6 ± 20.6 vs. 72.2 ± 18.7; KOOS 50.0 ± 18.9 vs. 81.7 ± 13.9; LYSHOLM 39.3 ± 19.5 vs. 79.8 ± 15.1). SF12 evaluation showed a significant increase in physical component summary (PCS) (31.2 ± 11.1 preoperative vs. 46.3 ± 9.9 at final follow-up), while mental component summary (MCS) remained stable (51.8 ± 8.9 vs. 57.3 ± 3.3). MOCART score revealed a mean overall score of 77 ± 15 at final follow-up. Integration to the adjacent cartilage was complete in 79%, incomplete in 21%. Defect filling was complete in 64%, incomplete in 36%.

CONCLUSION

Significant improvement of knee function and restoration of homogenous cartilage morphology could be achieved with simultaneous AMIC procedure and bone grafting in 2/3 of all patients with large osteochondral lesions at 4 years postoperatively.

Biomechanical performance of the Actifit® scaffold is significantly improved by selection of irrigation fluid

PURPOSE

Clinical reports on meniscal scaffolds seem promising, albeit relatively paucity exists regarding their biomechanical behavior. The aim of the study is to delineate the impact of differing suture materials and the type as well as the temperature of the irrigation fluid on the pull-out strength of a polyurethane meniscal scaffold (Actifit^®).

MATERIALS AND METHODS

128 specimens were utilized with horizontal sutures and uniaxial load-to-failure testing was performed. We compared two different suture materials-polydioxanone (PDS) and non-absorbable, braided polyester sutures (NABP)-as well as two common irrigation fluids-lactated Ringer's and electrolyte-free, hypotonic Mannitol-Sorbitol. All specimens were further evaluated according to two different temperatures [room temperature (20 °C) and near-core body temperature (37 °C)].

RESULTS

Mean load-to-failure was 53.3 ± 6.5 N. There was no significant difference between the NABP and the PDS group. Ringer group showed a significantly higher load-to-failure compared to Purisole (P = .0002). This was equivalent for both PDS (P = .0008) and NABP sutures (P = .0008). Significantly higher failure loads could be established for the 37° group (P = .041); yet, this difference was neither confirmed for the PDS or in in the NABP subgroup. Only the subgroup using Purisole at 37° showed significantly higher failure loads compared to 20° (P = .017).

CONCLUSIONS

This study underlines the potential to improve pull-out strength during implantation of an Actifit^® scaffold by alteration of the type of irrigation fluid. Lactated Ringer solution provided the highest construct stability in regard to load-to-failure testing and should be considered whenever implantation of a polyurethane meniscal scaffold is conducted.

Biomechanical performance of a collagen meniscus implant with regard to suture material and irrigation fluid

BACKGROUND

The role of meniscus scaffolds remains controversial as failure rates remain high. The aim of this study was to evaluate the pullout strength of different suture materials used for fixation of the Collagen Meniscus Implant (CMI) regarding different suture materials, and type or temperature of irrigation fluid.

METHODS

One-hundred and twelve specimens were utilized with horizontal sutures and mounted to a dedicated test device. Loads were applied perpendicular to the CMI, until failure. Two differing suture materials - polydioxanone (PDS) and non-absorbable, braided polyester sutures (NABP) - were evaluated. Additionally, two common irrigation fluids - lactated Ringer's and electrolyte-free, hypotonic Mannitol-Sorbitol solution - were evaluated. Specimens were further evaluated according to different temperatures of the irrigation fluid. Half of the constructs were tested at room temperature (20°C) and half were evaluated at near-core body temperature (37°C).

RESULTS

PDS sutures showed a significantly higher load-to-failure compared to NABP sutures (P=0.0008). Regarding the type of irrigation fluid, the electrolyte-free Mannitol-Sorbitol solution showed a significantly higher load-to-failure compared to the overall Ringer group (P b 0.0001). This was equivalent for both the PDS (P=0.015) and for the NABP sutures (P b 0.0001). The temperature of the irrigation fluid did not significantly influence load-to-failure.

CONCLUSIONS

PDS sutures and electrolyte-free Mannitol-Sorbitol irrigation fluid provided the best biomechanical properties regarding load-to-failure testing. This study underlines the potential to improve construct stability for the CMI by alteration of the suture material and the type of irrigation fluid, which should be considered whenever scaffold fixation is conducted.

The influence of applied internal and external rotation on the pivot shift phenomenon

PURPOSE

The pivot shift test is performed in different techniques and the rotation of the tibia seems to have a significant impact on the amount of the pivot shift phenomenon. It has been hypothesised that external rotation will increase the phenomenon due to less tension at the iliotibial band in knee extension.

METHODS

Twenty-four patients with unilateral anterior cruciate ligament insufficiency were included prospectively. The pivot shift test was performed bilaterally in internal and external tibial rotation under general anaesthesia. Knee motion was captured using a femoral and a tibial inertial sensor. The difference between positive and negative peak values in Euclidean norm of acceleration was calculated to evaluate the amount of the pivot shift phenomenon.

RESULTS

The pivot shift phenomenon was significantly increased in patients with ACL insufficiency when the test was performed in external [mean 5.2 ms^- 2 (95% CI 4.3-6.0)] compared to internal tibial rotation [mean 4.4 ms^- 2 (95% CI 3.5-5.4)] (p = 0.002). In healthy, contralateral knees did not show any difference between external [mean 4.0 ms^- 2 (95% CI 3.3-4.7)] and internal tibial rotation [mean 4.0 ms^- 2 (95% CI 3.4-4.6)] (ns).

CONCLUSIONS

The pivot shift phenomenon was increased with external rotation in ACL-insufficient knees, and therefore, one should perform the pivot shift test, rather, in external rotation to easily evoke the, sometimes difficult to detect, pivot shift phenomenon.

LEVEL OF EVIDENCE

I (diagnostic study).

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.

All-arthroscopic treatment of tibial avulsion fractures of the posterior cruciate ligament

Background: The posterior cruciate ligament (PCL) avulsion fracture from its tibial insertion is a rare condition. Despite the further technical advent in refixation of avulsion fractures, the reported failure rate of current approaches remains high and the optimal surgical technique has not been elucidated yet.

The purpose of the current study is to present an all-inside arthroscopic reconstruction technique for bony tibial avulsion fractures of the PCL and initial clinical outcomes.

Methods: Patients underwent a thorough clinical and radiological examination of both knees at 3, 6, 12, 18, and if possible also at 24 months.

Clinical evaluation included subjective and objective IKDC 2000, Lysholm score, and KOOS score. Radiographic imaging studies included CT scans for assessment of osseous integration and anatomic reduction of the bony avulsion. In addition to that posterior stress radiographs of both knees using the Telos device (Arthrex, Naples, USA) were conducted to measure posterior tibial translation.

Results: A total of four patients (1 female, 3 male; ø 38 (± 18) years), who underwent arthroscopic refixation of a PCL avulsion fracture using the Tight Rope device were enrolled in this study. Mean follow up was 22 [18–24] months.

The mean subjective IKDC was 72.6% (± 9.9%). Regarding the objective IKDC three patients accounted for grade A, one patient for grade C. The Lysholm score yielded 82 (± 6.9) points. The KOOS score reached 75% (± 13%; symptoms 76%, pain 81%, function 76%, sports 66%, QoL 64%).

All patients showed complete osseous integration and anatomic reduction of the bony avulsion. The mean posterior tibial translation at final follow up was 2.8 [0–7] mm.

Conclusions: All-arthroscopic treatment of tibial avulsion fractures of the posterior cruciate ligament provides satisfactory clinical results in a preliminary patient cohort. It is a reproducible technique, which minimizes soft tissue damage and obviates a second surgery for hardware removal. Further clinical studies with larger patient cohorts and a control group are needed to further confirm these preliminary results.

Arthroscopic Treatment of Acute Tibial Avulsion Fracture of the Posterior Cruciate Ligament Using the TightRope Fixation Device

Avulsion fracture of the posterior cruciate ligament from its tibial insertion is a rare condition. Early surgical treatment has been regarded as necessary, but the optimal surgical technique remains unclear. The purpose of this technical note is to present a novel all-inside arthroscopic reconstruction technique for bony tibial avulsion fractures of the posterior cruciate ligament using the TightRope device (Arthrex, Naples, FL).

[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)]

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.

Effects of indigo carmine on human chondrocytes in vitro

Joint infections following or accompanying superficious soft tissue infections are severe complication in orthopedic surgery. The use of intra-articular blue staining is a helpful method to visualize a fistula and to differentiate between superficial and intra-articular infections. Regarding this clinical implication data about the effects of indigo carmine, a frequently used blue staining substance, on cartilage is missing. The hypothesis of this study was that indigo carmine damages human chondrocytes in a time and concentration dependent manner. Human chondrocytes were isolated from donors with osteoarthritis who were treated with TKA. Cells were cultivated and treated with different concentrations of indigo carmine for 5 and 10 minutes. Morphologic damage was examined by light microscopy. Toxicity was quantified by counting vital cell number and lactate dehydrogenase (LDH) expression. Analysis by light microscopy showed defected cell structure and loss of cell number after treatment with 100% indigo carmine for 10 minutes. Treatment with 10% and 1% indigo carmine showed no significant cell defects and loss of cells. Counting vital cell number showed loss of vital cells after treatment with 100% and 10% indigo carmine for 10 minutes. LDH expression was significantly increased after treatment with 100% indigo carmine.Toxic effects were shown after treatment with indigo carmine. Therefore, it should be used in 1:100 dilution. This is both, sufficient for visualizing a fistula in a possible clinical application and could be protective for chondrocytes.

Sterilization with electron beam irradiation influences the biomechanical properties and the early remodeling of tendon allografts for reconstruction of the anterior cruciate ligament (ACL)

Although allografts for anterior cruciate ligament (ACL) replacement have shown advantages compared to autografts, their use is limited due to the risk of disease transmission and the limitations of available sterilization methods. Gamma sterilization has shown detrimental effects on graft properties at the high doses required for sufficient pathogen inactivation. In our previous in vitro study on human patellar tendon allografts, Electron beam (Ebeam) irradiation showed less detrimental effects compared to gamma sterilization (Hoburg et al. in Am J Sports Med 38(6):1134-1140, 2010). To investigate the biological healing and restoration of the mechanical properties of a 34 kGy Ebeam treated tendon allograft twenty-four sheep underwent ACL replacement with either a 34 kGy Ebeam treated allograft or a non-sterilized fresh frozen allograft. Biomechanical testing of stiffness, ultimate failure load and AP-laxity as well as histological analysis to investigate cell, vessel and myofibroblast-density were performed after 6 and 12 weeks. Native sheep ACL and hamstring tendons (HAT, each n = 9) served as controls. The results of a previous study analyzing the remodeling of fresh frozen allografts (n = 12) and autografts (Auto, n = 18) with the same study design were also included in the analysis. Statistics were performed using Mann-Whitney U test followed by Bonferroni-Holm correction. Results showed significantly decreased biomechanical properties during the early remodeling period in Ebeam treated grafts and this was accompanied with an increased remodeling activity. There was no recovery of biomechanical function from 6 to 12 weeks in this group in contrast to the results observed in fresh frozen allografts and autografts. Therefore, high dose Ebeam irradiation investigated in this paper cannot be recommended for soft tissue allograft sterilization.

[Driving behavior of cardiovascular patients as affected by beta receptor blockers]

18 male patients under betablocker therapy adapted to their individual stage of hypersympathicotonic circulatory regulation disturbances were tested in a motor-vehicle simulator to find out possible changes of their driving ability. Besides observing driving-style and reactions, the following parameters were controlled: blood pressure, time of pulse waves, heart rate. Speeds of deviation angles (= deviation from straight line per time unit) decreased significantly. No differences between tests under betablocker medication and without it could be demonstrated, neither in simple-reaction times nor in the more complex multiple-reaction times, which can be compared with realistic traffic situations. Blood pressure and heart rate showed more significant decreases after medication than in tests without previous betablocker treatment. The results prove that the betablocking agent Bupranolol does not influence the ability of car-driving, not even in case of semichronical application.

[Serum ribonuclease and its importance for renal diagnosis (author's transl)]

Ribonuclease activity in the serum is recommended in the literature for the diagnosis of tumors, especially carcinoma of the pancreas. On the other hand it has long been suspected that serum RNAase increases when renal function is reduced. It is shown that the RNAase activity in human serum correlates well the creatinine clearance. Tumor diseases are frequently coupled with reduced renal function which leads to a rise in RNAase. The serum RNAase activity is therefore only of limited application for tumor diagnosis. The rise in RNAase activity in the serum is, however, a useful measure for the reduced renal function. The analysis of serum RNAase could replace the determination of creatinine clearance.

Function of modified nucleosides 7-methylguanosine, ribothymidine, and 2-thiomethyl-N6-(isopentenyl)adenosine in procaryotic transfer ribonucleic acid

To elucidate subtle functions of transfer ribonucleic acid (tRNA) modifications in protein synthesis, pairs of tRNA's that differ in modifications at specific positions were prepared from Bacillus subtilis. The tRNA's differ in modifications in the anticodon loop, the extra arm, and the TUC loop. The functional properties of these species were compared in aminoacylation, as well as in initiation and peptide bond formation, at programmed ribosomes. These experiments demonstrated the following. (i) In tRNA(f) (Met) the methylation of guanosine 46 in the extra arm to 7-methylguanosine by the 7-methylguanosine-forming enzyme from Escherichia coli changes the aminoacylation kinetics for the B. subtilis methionyl-tRNA synthetase. In repeated experiments the V(max) value is decreased by one-half. (ii) tRNA(f) (Met) species with ribothymidine at position 54 (rT54) or uridine at position 54 (U54) were obtained from untreated or trimethoprim-treated B. subtilis. The formylated fMet-tRNA(f) (Met) species with U54 and rT54, respectively, function equally well in an in vitro initiation system containing AUG, initiation factors, and 70s ribosomes. The unformylated Met-tRNA(t) (Met) species, however, differ from each other: "Met-tRNA(f) (Met) rT" is inactive, whereas the U54 counter-upart effectively forms the initiation complex. (iii) Two isoacceptors, tRNA(1) (Phe) and tRNA(2) (Phe), were obtained from B. subtilis. tRNA(1) (Phe) accumulates only under special growth conditions and is an incompletely modified precursor oftRNA(2) (Phe): in the first position of the anticodon, guanosine replaces Gm, and next to the 3' end of the anticodon (isopentenyl)adenosine replaces 2-thiomethyl-N(6)-(isopentenyl)adenosine. Both tRNA's behave identically in aminoacylation kinetics. In the factor-dependent AUGU(3)-directed formation of fMet-Phe, the undermodified tRNA(1) (Phe) is always less efficient at Mg(2+) concentrations between 5 and 15 mM than its mature counterpart.