KnorpelRegister DGOU Research Articles

Decision making for concomitant high tibial osteotomy (HTO) in cartilage repair patients based on a nationwide cohort study of 4968 patients

BackgroundHigh tibial osteotomy (HTO) for varus deformities is a common concomitant treatment in cartilage surgery. Aim of the present study was to analyze factors influencing the decision towards accompanying HTO in patients with cartilage defects of the medial femoral condyle, such as the amount of varus deformity.MethodsData from 4986 patients treated for cartilage defects of the knee from the German Cartilage Registry (KnorpelRegister DGOU) were used for the current analysis. Seven hundred and thirty-six patients fulfilled the inclusion criteria. Their data were analyzed for factors influencing the decision towards performing a concomitant HTO using t test, univariate and multivariate binary logistic regression models.ResultsThe break point at which the majority of patients receive a concomitant HTO is 3° of varus deformity. Several factors apart from the amount of varus deformity (5.61 ± 2.73° vs. 1.72 ± 2.38°, p < 0.00) differed significantly between the group of patients with HTO and those without. These included defect size (441.6 ± 225.3 mm2 vs. 386.5 ± 204.2 mm2, p = 0.001), symptom duration (29.53 ± 44.58 months vs. 21.85 ± 34.17 months, p = 0.021), defect grade (62.5% IVa/IVb vs. 57.3% IVa/IVb, p = 0.014), integrity of corresponding joint surface (10.8% grade III–IV vs. 0.2% grade III–IV, p < 0.001), meniscus status (15.5% > 1/3 resected vs. 4.4% > 1/3 resected, p < 0.001) and number of previous surgeries (1.01 ± 1.06 vs. 0.75 ± 1.00, p = 0.001). In the stepwise multivariate binary logistic regression test, only the amount of varus deformity, symptom duration and quality of the corresponding joint surface remained significant predictors associated with performing a concomitant HTO.ConclusionBased upon data from a nationwide cohort, additional HTO in context with cartilage repair procedures of the medial femoral condyle is frequently performed even in mild varus deformities less than 5°. Other factors also seem to influence decision for HTO.

Concomitant ankle instability has a negative impact on the quality of life in patients with osteochondral lesions of the talus: data from the German Cartilage Registry (KnorpelRegister DGOU).

The purpose of this study was to compare patients with osteochondral lesions of the talus (OCLT) with and without concomitant chronic ankle instability (CAI). Data from the German Cartilage Registry (KnorpelRegister DGOU) for 63 patients with a solitary OCLT were used. All patients received autologous matrix-induced chondrogenesis (AMIC) for OCLT treatment. Patients in group A received an additional ankle stabilisation, while patients in group B received AMIC alone. Both groups were compared according to demographic, lesion-related, and therapy-related factors as well as baseline clinical outcome scores at the time of surgery. The Foot and Ankle Ability Measure (FAAM), the Foot and Ankle Outcome Score (FAOS), and the Numeric Rating Scale for Pain (NRS) were used. Patients in group A were older compared to group B [median 34years (range 20-65years) vs. 28.5years (range 18-72years)]; the rate of trauma-associated OCLTs was higher (89.7% vs. 38.3%); more patients in group A had a previous non-surgical treatment (74.1% vs. 41.4%); and their OCLT lesion size was smaller [median 100 mm2 (range 15-600 mm2) vs. 150 mm2 (range 25-448 mm2)]. Most OCLTs were located medially in the coronary plane and centrally in the sagittal plane in both groups. Patients in group A had worse scores on the FAOS quality-of-life subscale compared to patients in group B. Patients with OCLT with concomitant CAI differ from those without concomitant CAI according to demographic and lesion-related factors. The additional presence of CAI worsens the quality of life of patients with OCLT. Patients with OCLT should be examined for concomitant CAI, so that if CAI is present, it can be integrated into the treatment concept. IV.

Is debridement beneficial for focal cartilage defects of the knee: data from the German Cartilage Registry (KnorpelRegister DGOU)

IntroductionFocal cartilage defects of the knee are often treated with arthroscopic debridement. Existing literature discussing the benefit of debridement for small articular cartilage lesions is scarce, especially if the debridement was not part of a combined operative cartilage procedure including meniscal and ligament repair. The purpose of this study was to examine the patients´ benefit after arthroscopic debridement for the treatment of isolated focal chondral defects with or without partial meniscus resection.Materials and methodsBaseline (preoperative data) and 12-month follow-up of the five Knee Osteoarthritis Outcome Score (KOOS) subscores and the Numeric Rating Scale (NRS) for pain were analyzed in 126 patients undergoing debridement for focal chondral defects of the knee from the German Cartilage Registry. Sub-analysis for patients receiving isolated debridement and debridement with concomitant partial resection of meniscal pathologies was performed. Thus, four subgroups were created according to the treated defect size and presence of meniscal pathologies: “debridement-only < 2 cm2”, “debridement-only > 2 cm2”, “debridement and partial meniscus resection < 2 cm2” and “debridement and partial meniscus resection > 2 cm2”.ResultsKOOS-subscores showed a significant increase from baseline to follow-up evaluation (p = 0.017–0.037) within the 126 patients. Sub-analysis showed significant improvement of all five KOOS-subscores in all three subgroups, except for the “debridement and partial meniscus resection > 2 cm2”—group: in this group the KOOS subscores symptoms and sports showed no significant improvement. The NRS scores revealed no significant changes from baseline to 12-month follow-up within the four subgroups.ConclusionAn overall benefit of arthroscopic debridement for focal cartilage lesions of the knee could be conducted. Isolated cartilage defects seem to benefit from debridement irrespectively of size. In patients with large cartilage defects (> 2 cm2) and concurrent meniscal pathology expectation to improvement should be humbled. Effective reduction of pain by arthroscopic debridement remains unclear.

Current Practice of Analysis and Treatment of underlying Varus Deformity in Patients with Cartilage Defects of the medial Femoral Condyle: Data of the German Cartilage Registry (KnorpelRegister DGOU)

Aims and Objectives: In the context of cartilage repair, identification of the underlying pathologies depends on detailed preoperative evaluation. High tibial osteotomy (HTO) for varus deformities is one of the most common concomitant treatments, though scientific evidence about efficiency of concomitant HTO is still limited. The present study was initiated to describe preoperative analysis of alignment and to analysis outcome comparing patients with combined cartilage repair and HTO with those who received cartilage repair procedures alone. Materials and Methods: The multicenter data (3855 data sets on April 15, 2018) was provided by the attending physician and a self-reported outcome analysis (KOOS). Inclusion criteria: Existence of a leg full length portrait, a single defect at the medial femoral condyle, either no accompanying surgery or a HTO and information on leg axis misalignment. For outcome evaluation patients were divided into three different groups with regard to the extent of varus deformity: MILD (0-4° varus), MODERATE (5-9° varus) and SEVERE (&gt; 10°). Statistical Analysis was performed using SPSS (IBM) Version 23. For detection of significances between different groups one-way ANOVA test was applied. P-values &lt; 0.05 were considered statistical significant. Results: In 55.1% (n=2125) of the patients a full leg weight-bearing radiographs has been performed preoperatively. Out of these 834 (39%) cases with isolated defects of the medial femoral condyle have been identified of which 179 received HTO in combination with the cartilage repair procedure (21.5%), while 411 cases have been treated with isolated cartilage repair (49.3%). From the remaining 385 patients, 256 patients were considered MILD (67,3%), 113 MODERATE (29.5%) and 4.2% (n=16) SEVERE. Incidence of HTO significantly depended on the degree of varus deformity for mild (19% HTO) and moderate (83% HTO) deformity, but there was no significance between the moderate and severe (81% HTO) group. Significant differences of the KOOS score could be shown preoperatively between the mild (mean: 57.3), as well as moderate (mean: 55.95), and the severe group (mean 39.53) and six months postoperatively between the mild (mean: 71.48) and the severe (mean: 52.6) group. Conclusion: The present analysis of a large patients cohort extracted from the German Cartilage Registry (KnorpelRegister DGOU) demonstrates that, against common guidelines, full-leg weigth-bearing radiographs are not conducted on a regular basis in patients assigned for cartilage repair procedures. In those cases with detailed preoperative analysis of alignment, the degree of deformity seems to influence the decision, whether a realignment procedure (HTO) is performed. For the moderate subgroup a trend towards better clinical outcome was found for combined treatment in terms of realignment and cartilage repair in comparison to cartilage repair alone. Since there was no difference in the MILD subgroup, more evidence is needed to proof, whether those patients benefit from a HTO or not.

Degenerative isolated cartilage defects of the patellofemoral joint are associated with more severe symptoms compared to trauma-related defects: results of the German Cartilage Registry (KnorpelRegister DGOU).

The purpose of this study was to utilize data from the German Cartilage Registry (KnorpelRegister DGOU) to examine the hypothesis that degenerative cartilage defects of the patellofemoral joint are associated with more severe clinical symptoms compared to trauma-related defects. All patients with isolated focal cartilage defects of the patellofemoral joint registered in the German Cartilage Registry until May 2017 were included in the study. Patients with previous surgery of the ipsilateral knee were excluded. Baseline data including etiology (traumatic, degenerative), size, location and ICRS grade of the cartilage defects as well as the duration of symptoms were analyzed. Clinical symptoms were evaluated by means of the numeric analog scale (NAS) for pain and the Knee injury and Osteoarthritis Outcome Score (KOOS). Group comparisons were performed using the Mann-Whitney-U test along with the Chi-squared test and Fisher's exact test. A bivariate correlation analysis and a multivariable linear regression analysis were performed to investigate the association between the defect characteristics and the clinical scores. A total of 423 patients (203 traumatic and 220 degenerative defects) were included. Isolated degenerative cartilage defects were found to have significantly more trochlear locations (28% vs. 18%; p = 0.006), significantly less ICRS grade 4 lesions (50% vs. 73%; p = 0.002) and a significantly smaller defect size [median 300 (IQR 105-400) vs. 300 (200-400) mm2] when compared to those from traumatic etiology. Traumatic defects showed significantly better KOOS-ADL [77 (60-90) vs. 69 (56-82); p = 0.005], KOOS-pain [69 (56-81) vs. 61 (47-75); p = 0.001] and NAS [2 (1-5) vs. 4 (1-6); p = 0.005] scores compared to degenerative defects. The correlation analysis revealed only weak correlations between the quantitative defect characteristics and clinical scores. Degenerative isolated cartilage defects in the patellofemoral joint are associated with more severe clinical symptoms in comparison to trauma-related defects. Additionally, they show a larger variance regarding their location with more trochlear defects. III.

What parameters affect knee function in patients with untreated cartilage defects: baseline data from the German Cartilage Registry.

To evaluate the factors influencing the baseline Knee Injury and Osteoarthritis Outcome Score (KOOS) in patients with knee cartilage defects and planned cartilage repair surgery and to provide baseline KOOS data from a large patient population. Between October 2013 and April 2017, a total of 2815 patients assigned for cartilage repair surgery were included into the German Cartilage Registry (KnorpelRegister DGOU) and their data were analyzed for the present study. Multivariate regression model and ANOVA were used to detect patient- and defect-specific factors with an influence on baseline KOOS. In addition, KOOS baseline data was calculated and compared according to these parameters. Sex, age, body mass index (BMI), and smoking status were revealed as patient-specific factors, and defect location and the number of previous knee and cartilage operations were revealed as defect-specific factors with a significant influence on baseline KOOS. Most subscores were affected in accordance with the total KOOS. Interestingly, defect ICRS grade, defect size, and symptom duration had no significant influence. The mean baseline KOOS was 56.7 (± 17.9). Men had significantly higher mean overall KOOS (60 ± 17.3 vs. 51.8 ± 17.6, p < 0.001) than women, and patients with a BMI over 30 and smokers scored significantly lower (58.07 ± 17.67 vs. 50.32 ± 17.29, p < 0.001; 57.64 ± 17.86 vs. 53.59 ± 18.06, p < 0.001). Patients with two or more previous knee operations as well as patients with more than one previous cartilage procedure also showed significantly lower overall KOOS (57.19 ± 17.89 vs. 54.56 ± 17.58, p < 0.001; 57.68 ± 18.01 vs. 52.72 ± 17.58, p < 0.001). Several factors influencing baseline KOOS data in patients with knee cartilage defects assigned for cartilage repair surgery could be detected. Their individual influence in the multivariate linear regression model was not very strong. Baseline data according to these criteria is presented in this paper.

Pain in Osteochondral Lesions of the Ankle - an Investigation Based on Data from the German Cartilage Registry (KnorpelRegister DGOU).

The aim of the study was to investigate parameters influencing the preoperative pain intensity in patients with osteochondral lesions of the ankle. The evaluation covered patient-related parameters such as age, sex, body mass index (BMI), as well as defect-related parameters, such as localisation, size and stage (according to the classification of the International Cartilage Repair Society [ICRS] and the Berndt-Harty-Loomer classification). We also examined the correlation between the different surgical techniques and additional factors, such as debridement of an impingement or stabilisation of the ankle on the one hand, and the preoperative pain intensity on the other. 259 patients with osteochondral lesions of the ankle were operated in 32 clinical centres between October 2014 and December 2016 and enrolled consecutively in the German Cartilage Registry (KnorpelRegister DGOU). 151 patients were available for analysis. The preoperative pain intensity was assessed at the time of surgery with online questionnaires, using the Numeric Rating Scale for pain (NRS). The median preoperative pain intensity in the complete study population (n = 151) was 3 (range 0 - 10). There was no correlation between the age and the preoperative pain intensity (ρ = - 0.06). Further, there was not detected a difference between the two genders according to the preoperative pain intensity (p = 0.31). In female patients a higher BMI correlated with a higher preoperative pain intensity (ρ = 0.16). Within the group of patients with a solitary treated talus lesion there was no difference according to the preoperative pain intensity between the different localizations of the defect (medial vs. lateral talus) (p = 0.82). Within the group of patients with a solitary treated talus or tibia lesion there was no correlation between the defective area or the lesion stage according to the ICRS classification on the one hand, and the preoperative pain intensity on the other (ρ = 0.09, and ρ = 0.04, respectively). According to the Berndt-Harty-Loomer classification a higher lesion stage (stage four and five) was associated with a higher preoperative pain intensity (ρ = 0.13). There was no difference according to the preoperative pain intensity between the group of patients that received a debridement of a bony or soft tissue impingement in addition to the cartilage therapy and the group of patients without this kind of additional therapy (p = 0.10). Further, there was no difference according to the preoperative pain intensity between the group of patients that received a stabilisation of the ankle joint in addition to the cartilage therapy and the group of patients without a stabilisation procedure (p = 0.83). Osteochondral lesions of the ankle can be associated with a moderate and in some cases high pain intensity. In female patients a higher BMI is associated with a higher pain intensity. Further, a higher lesion stage according to the Berndt-Harty-Loomer classification is associated with a higher pain intensity, which highlights the clinical relevance of this classification.

Revision Surgery After Cartilage Repair: Data From the German Cartilage Registry (KnorpelRegister DGOU).

Background:Various operative strategies have been introduced to restore the integrity of articular cartilage when injured. The frequency of revision surgery after cartilage regenerative surgery remains incompletely understood.Purpose/Hypothesis:The purpose of this study was to identify the reasons for revision surgery after cartilage regenerative surgery of the knee. We hypothesized that in a large patient cohort, revision rates would differ from those in the current literature.Study Design:Case-control study; Level of evidence, 3.Methods:A total of 2659 complete data sets from the German Cartilage Registry were available for analyses. In brief, baseline data were provided by the attending physician at the time of index surgery. Follow-up data were collected using a web-based questionnaire inquiring whether patients had needed revision surgery during follow-up, which was defined as the endpoint of the present analysis.Results:A total of 88 patients (3.3%) reported the need for revision surgery as early as 12 months postoperatively. Among the most common causes were arthrofibrosis (n = 27) and infection (n = 10). Female patients showed a significantly greater complication rate (4.5%) when compared with male patients (2.6%; P = .0071). The majority of cartilage lesions were located at the medial femoral condyle (40.2%), with a mean defect size of 3.5 ± 2.1 cm2. Neither the location nor defect size appeared to lead to an increased revision rate, which was greatest after osteochondral autografts (5.2%) and autologous chondrocyte implantation (4.6%). Revision rates did not differ significantly among surgical techniques. Chi-square analysis revealed significant correlations between the number of previous joint surgeries and the need for revision surgery (P = .0203). Multivariate regression analysis further confirmed sex and the number of previous surgeries as variables predicting the need for early revision surgery.Conclusion:The low early revision rates found in this study underline that today’s cartilage repair surgeries are mostly safe. Although invasiveness and techniques differ greatly among the procedures, no differences in revision rates were observed. Specific factors such as sex and the number of previous surgeries seem to influence overall revision rates and were identified as relevant risk factors with regard to patient safety.

Parameters influencing complaints and joint function in patients with osteochondral lesions of the ankle-an investigation based on data from the German Cartilage Registry (KnorpelRegister DGOU).

Patients with osteochondral lesions of the ankle represent a heterogeneous population with traumatic, posttraumatic and idiopathic forms of this pathology, where the etiology of the idiopathic form is principally unknown. The aim of this study was to classify the heterogeneous patient population according to the patients' complaints and joint function. Data from the German Cartilage Registry (KnorpelRegister DGOU) was analyzed for this purpose to investigate whether traumatic and posttraumatic lesions cause more complaints and loss of joint function than idiopathic lesions. Moreover, it was sought to determine if lesion localization, defective area, stage, patient age, gender, and body mass index (BMI) are related to patients' complaints and loss of joint function. A 117 patients with osteochondral lesions of the ankle were operated in 20 clinical centers in the period between October 2014 and January 2016. Data collection was performed by means of a web-based Remote Data Entry system at the time of surgery. Patients' complaints and joint function were assessed with online questionnaires using the German versions of the Foot and Ankle Ability Measure (FAAM) and the Foot and Ankle Outcome Score (FAOS), followed by statistical data evaluation. No significant difference was indicated between the groups with traumatic/posttraumatic lesions and idiopathic lesions with regard to most of the patients' complaints and joint function, excluding the category Life quality of the FAOS score, where patients with idiopathic lesions had a significantly better quality of life (p = 0.02). No significant association was detected between lesion localization, defective area, patient age, gender, and BMI on the one hand, and patients' complaints and joint function on the other. Similarly, no significant association was found between lesion stage according to the International Cartilage Repair Society (ICRS) classification and patients' complaints and joint function. However, a higher lesion stage according to the classification of Berndt and Harty, modified by Loomer, was significantly associated with more complaints and loss of joint function in some categories of the FAAM and FAOS scores (p ≤ 0.04). Etiology of the lesion, lesion localization, defective area, lesion stage according to the ICRS classification, patient age, gender, and BMI do not seem to be of considerable relevance for prediction of patients' complaints and loss of joint function in osteochondral lesions of the ankle. Using the classification of Berndt and Harty, modified by Loomer, seems to be more conclusive.

A Registry for Evaluation of Efficiency and Safety of Surgical Treatment of Cartilage Defects: The German Cartilage Registry (KnorpelRegister DGOU).

BackgroundThe need for documentation in cartilage defects is as obvious as in other medical specialties. Cartilage defects can cause significant pain, and lead to reduced quality of life and loss of function of the affected joint. The risk of developing osteoarthritis is high. Therefore, the socioeconomic burden of cartilage defects should not be underestimated.ObjectiveThe objective of our study was to implement and maintain a registry of all patients undergoing surgical treatment of cartilage defects.MethodsWe designed this multicenter registry for adults whose cartilage defects of a knee, ankle, or hip joint are treated surgically. The registry consists of two parts: one for the physician and one for the patient. Data for both parts will be gathered at baseline and at 6-, 12-, 24-, 36-, 60-, and 120-month follow-ups.ResultsTo date, a wide range of German, Swiss, and Austrian trial sites are taking part in the German Cartilage Registry, soon to be followed by further sites. More than 2124 (as of January 31, 2016) cases are already documented and the first publications have been released.ConclusionsThe German Cartilage Registry addresses fundamental issues regarding the current medical care situation of patients with cartilage defects of knee, ankle, and hip joints. In addition, the registry will help to identify various procedure-specific complications, along with putative advantages and disadvantages of different chondrocyte products. It provides an expanding large-scale, unselected, standardized database for cost and care research for further retrospective studies.Trial RegistrationGerman Clinical Trials Register: DRKS00005617; https://drks-neu.uniklinik-freiburg.de/ drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00005617 (Archived by WebCite at http://www.webcitation.org/6hbFqSws0)

Cartilage repair surgery for full-thickness defects of the knee in Germany: indications and epidemiological data from the German Cartilage Registry (KnorpelRegister DGOU).

Treatment of cartilage defects of the knee remains an important issue with high relevance. In October 2013 the German Cartilage Registry (KnorpelRegister DGOU) was initiated in order to study indications, epidemiology and (clinical) outcome of different cartilage repair techniques. The present evaluation of the registry baseline data was initiated to report common practices of cartilage repair surgery in Germany. 1065 consecutive patients who underwent surgical cartilage treatment of the knee have been included (complete data sets available in 1027 cases; FU rate 96.4%) between October 1, 2013 and June 30, 2015. Data collection was performed using a web-based RDE System. All data were provided by the attending physician at the time of arthroscopic or open surgery of the affected knee. In 1027 cartilage repair procedures, single defects were treated in 80% of the cases with the majority of the defects located on the medial femoral condyle, followed by the patella. Degenerative defects grade III or IV according to ICRS were treated in 60% of the cases and therefore were found more frequently compared to traumatic or post-traumatic lesions. Autologous chondrocyte implantation (ACI) was the most common technique followed by bone marrow stimulation (BMS) and osteochondral transplantation (OCT). While ACI was performed in defects with a mean size of 4.11cm(2) SD SD 2.16), BMS and OCT (1.51cm(2), SD 1.19; p<0.01) were applied in significantly smaller defects (both p<0.01). Independent of defect size, the ratio of ACI versus BMS applications differed between different defect locations. ACI was used preferably in defects located on the patella. The present analysis of data from the German Cartilage Registry shows that the vast majority of cartilage repair procedures were applied in degenerative, non-traumatic cartilage defects. Experts in Germany seem to follow the national and international guidelines in terms that bone marrow stimulation is applied in smaller cartilage defects while cell-based therapies are used for the treatment of larger cartilage defects. In patellar cartilage defects a trend towards the use of cell-based therapies has been observed.

Characteristics and associated factors of Klee cartilage lesions: preliminary baseline-data of more than 1000 patients from the German cartilage registry (KnorpelRegister DGOU).

Knee cartilage lesions are very frequent in arthroscopic surgery. This multi-center-study was aimed to evaluate the distribution and possible associated factors of these pathologies in more than 1000 patients. The German cartilage registry (KnorpelRegister DGOU) started in 2013. In this paper, we present the baseline-data (distribution of knee cartilage lesions and the demographic data) of more than 1000 cases since the registries' start-up. A total number of 47 centers were involved into this multicenter study. A total of 1071 patients primary were registered. Degenerative knees 629 times (61.8%) and injured knees 302 times (29.6%) were involved. In the remaining 89 knees (8.7%) the genesis of cartilage lesions was unclear. Single defects were observed in 792 cases (77.6%). Most frequently the medial femoral condyle or the patella was affected. In 78 knees (7.6%) the main-defect was associated with a defect of the corresponding joint surface. In the remaining cases complex cartilage damages were found. Our results are in confirmation with other multicenter studies. But these former studies did not differentiate into traumatic and degenerative lesions. Furthermore no characteristics were given regarding to single, kissing or complex lesions. Thus this database will be a sufficient instrument for the investigation of the "natural course" of cartilage lesions, but above all about the effectiveness of different treatment options.

The German Cartilage Registry (KnorpelRegister DGOU) for evaluation of surgical treatment for cartilage defects: experience after six months including first demographic data

The German Cartilage Registry (KnorpelRegister DGOU) has been introduced in October 2013 and aims on the evaluation of patients who underwent cartilage repair for symptomatic cartilage defects. It represents a nation-wide cohort study which has been introduced by the working group "Tissue Regeneration" of the Germany Society of Orthopaedic Surgery and Traumatology and is technically based upon a web-based remote data entry (RDE) system. The present article describes first experiences with the registry including patient and treatment characteristics. Between October 2013 and April 2014, a total of 230 patients who had undergone surgical cartilage repair for symptomatic full-thickness cartilage defects of the knee has been included in the German Cartilage Registry from 23 cartilage repair centres. Mean age was 37.11 years (SD 13.61) and mean defect size was 3.68 cm(2) (SD 0.23). Since the introduction of the KnorpelRegister DGOU the total number of registered patients has increased steadily up to the most recent figure of 72 patients within one month. Patients were treated mainly according to the recommended therapies. The highest percentage in therapy is represented by the bone marrow stimulation techniques (55.02 %) as well as by the autologous chondrocyte transplantation (34.92 %). Unlike the patient collective in the majority of prospective randomised controlled trials, the patient population within the registry shows a high proportion of patients with accompanying pathologies, with an age of more than 50 years at the time of treatment and with unfavourably assessed accompanying pathologies such as an affection of the opposite cartilage surface or a previously resected meniscus. In summary, the technical platform and forms of documentation of the KnorpelRegister DGOU have proved to be very promising within the first six months. Unlike data from other clinical trials, the previous analysis of the patients' data and therapies reflects successfully the actual medical care situation of patients with cartilage defects of the knee joint. This analysis also provides new information on subgroups of patients that have not yet been recorded in the scientific literature. This will be part of the first analysis of clinical treatment data. An expansion of the KnorpelRegister DGOU to patients with cartilage defects of the ankle and hip joints is already decided upon and initialised.