Secondary matrix-associated autologous chondrocyte implantation after failed cartilage repair shows superior results when combined with autologous bone grafting: Findings from the German Cartilage Registry (KnorpelRegister DGOU).

PURPOSE: The aim of this study was to evaluate whether additive autologous bone grafting (ABG) improves clinical outcome and survival in revision matrix-associated autologous chondrocyte implantation (M-ACI) after failed cartilage repair (CR). METHODS: A retrospective, registry-based, matched-pair analysis was performed to compare patient-reported outcomes and survival in secondary M-ACI with or without additional bone grafting for focal full-thickness cartilage defects of the knee and to compare it with those in primary M-ACI. Patients were matched for age, sex, body mass index, defect size and localization, and number of previous CRs. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was assessed over a follow-up period of 36 months. The patient acceptable symptomatic state, the clinical response rate and the survival of the subgroups were determined. RESULTS: A total of 818 patients were matched. Revision M-ACI (n = 238) with concomitant bone grafting was associated with significantly higher PRO as measured by KOOS (80.8 ± 16.8 vs. 72.0 ± 17.5, p = 0.032) and higher CRR (81.4% vs. 52.0%, p = 0.018) at 36 months compared to patients with revision M-ACI alone. KOOS and KOOS improvement in these patients did not differ from those who underwent primary M-ACI (p = n.s.). The combination of M-ACI and ABG resulted in a significantly higher KOOS at 36 months than M-ACI alone, regardless of whether bone marrow stimulation (89.6 ± 12.5 vs. 68.1 ± 17.9, p = 0.003) or ACI (82.6 ± 17.0 vs. 72.8 ± 16.0, p = 0.021) was performed before. Additional bone grafting results in equivalent survival rates at 7 years in secondary compared to primary M-ACI (83% vs. 84%, p = n.s.). CONCLUSIONS: Regardless of the type of previous CR, additional bone grafting in secondary M-ACI improves the clinical outcome, response rate and survival at 36 months compared to M-ACI alone. Secondary M-ACI with ABG had comparable clinical response and survival rates to primary M-ACI. Therefore, subchondral bone should be treated even in cases of mild bone involvement in revision M-ACI. LEVEL OF EVIDENCE: Level III.

Orthopaedic surgeons display a positive outlook towards artificial intelligence: A survey among members of the AGA Society for Arthroscopy and Joint Surgery.

Purpose: The purpose of this study was to evaluate the perspective of orthopaedic surgeons on the impact of artificial intelligence (AI) and to evaluate the influence of experience, workplace setting and familiarity with digital solutions on views on AI. Methods: Orthopaedic surgeons of the AGA Society for Arthroscopy and Joint Surgery were invited to participate in an online, cross-sectional survey designed to gather information on professional background, subjective AI knowledge, opinion on the future impact of AI, openness towards different applications of AI, and perceived advantages and disadvantages of AI. Subgroup analyses were performed to examine the influence of experience, workplace setting and openness towards digital solutions on perspectives towards AI. Results: Overall, 360 orthopaedic surgeons participated. The majority indicated average (43.6%) or rudimentary (38.1%) AI knowledge. Most (54.5%) expected AI to substantially influence orthopaedics within 5-10 years, predominantly as a complementary tool (91.1%). Preoperative planning (83.8%) was identified as the most likely clinical use case. A lack of consensus was observed regarding acceptable error levels. Time savings in preoperative planning (62.5%) and improved documentation (81%) were identified as notable advantages while declining skills of the next generation (64.5%) were rated as the most substantial drawback. There were significant differences in subjective AI knowledge depending on participants' experience (p = 0.021) and familiarity with digital solutions (p < 0.001), acceptable error levels depending on workplace setting (p = 0.004), and prediction of AI impact depending on familiarity with digital solutions (p < 0.001). Conclusion: The majority of orthopaedic surgeons in this survey anticipated a notable positive impact of AI on their field, primarily as an assistive technology. A lack of consensus on acceptable error levels of AI and concerns about declining skills among future surgeons were observed. Level of Evidence: Level IV, cross-sectional study.

A Narrative Review of the Roles of Chondromodulin-I (Cnmd) in Adult Cartilage Tissue.

Articular cartilage is crucial for joint function but its avascularity limits intrinsic repair, leading to conditions like osteoarthritis (OA). Chondromodulin-I (Cnmd) has emerged as a key molecule in cartilage biology, with potential implications for OA therapy. Cnmd is primarily expressed in cartilage and plays an important role in chondrocyte proliferation, cartilage homeostasis, and the blocking of angiogenesis. In vivo and in vitro studies on Cnmd, also suggest an involvement in bone repair and in delaying OA progression. Its downregulation correlates with OA severity, indicating its potential as a therapeutic target. Further research is needed to fully understand the mode of action of Cnmd and its beneficial implications for managing OA. This comprehensive review aims to elucidate the molecular characteristics of Cnmd, from its expression pattern, role in cartilage maintenance, callus formation during bone repair and association with OA.

Hydrogel-based and spheroid-based autologous chondrocyte implantation of the knee show similar 2-year functional outcomes: An analysis based on the German Cartilage Registry (KnorpelRegister DGOU).

PURPOSE: To compare short-term patient-reported outcomes (PRO) of two contemporary matrix-associated autologous chondrocyte implantation (M-ACI) products for the treatment of large articular cartilage defects of the knee. METHODS: A retrospective, registry-based, matched-pair analysis was performed, comparing PRO of patients undergoing isolated M-ACI with either Spherox™, a spheroid-based ACI (Sb-ACI), or NOVOCART™ Inject, a hydrogel-based ACI product (Hb-ACI), for a focal full-thickness cartilage defect of the knee ≥4 cm2. Matching parameters included age, sex, body mass index, defect size, defect localization, symptom duration and previous surgeries. The Knee Injury and Osteoarthritis Outcome Score (KOOS) and the International Knee Documentation Committee (IKDC) score were obtained up to the 24-month follow-up. The total KOOS response rate and percentage of patients attaining a substantial clinical benefit (SCB) in KOOS subscores were calculated. RESULTS: A total of 45 patients per group were matched. The response rate after 24 months was not significantly different between the groups (Sb-ACI 64.4% vs. Hb-ACI 82.2%, p = 0.057). The number of patients with a SCB at 24 months was not significantly different in any KOOS subscore, despite significantly higher improvement of the total KOOS (14.8 ± 16.2 vs. 21.5 ± 15.4, p = 0.047) and KOOS pain in the Hb-ACI group (12.2 ± 18.6 vs. 20.6 ± 19.1, p = 0.037). The IKDC score in the Hb-ACI group was significantly higher at the 12- and 24-month follow-up (60.7 ± 20.2 vs. 70.9 ± 18.0, p = 0.013). CONCLUSION: The response rate and number of patients achieving an SCB were not significantly different between patients treated with Sb-ACI or Hb-ACI. Both procedures can achieve favourable 2-year PRO. Hb-ACI was associated with better PRO between 1 and 2 years postoperatively; however, the clinical relevance of this benefit is yet to be proven. LEVEL OF EVIDENCE: III, Retrospective comparative study.

Open-wedge high tibial osteotomy with and without bone void filler: Allograft leads to faster bone union and weight bearing with comparable return to work and sports rates.

PURPOSE: To compare the clinical and radiological outcome of open-wedge high tibial osteotomy (OWHTO) with allogenous bone chips to a control group without bone void filler. The focus was on the rates and timelines of return to work (RTW) and return to sports (RTS), given the significance of these factors for the satisfaction of young and active patients. METHODS: One hundred and ninety-five cases of OWHTO (112 cases with allograft vs. 83 cases without graft) with a follow-up of 17 ± 4.8 months were included in this retrospective analysis. Various metrics were investigated, including time to return to full weight bearing, RTW and RTS rates and timelines, International Knee Documentation Committee (IKDC) Score, Cincinnati-Sportsmedicine and Orthopaedic Centre Score and Tegner Score. The time to bone union was determined on radiographs taken at 6, 16, 28 and 53 weeks. RESULTS: Patients returned to full weight bearing after 8.8 ± 4.8 weeks. RTW was possible for 92.8% after 13.7 ± 12.3 weeks. 96.2% returned to sports after 22.7 ± 8.3 weeks, but the number of disciplines and workouts per week diminished (p < 0.001, p = 0.006). A shift to low-impact and recreational sports was observed. Patients with allograft filling had earlier bone union (21 ± 12.3 vs. 31.9 ± 14.2 weeks, p < 0.001) and returned faster to full weight bearing (8.2 ± 4.5 vs. 9.8 ± 5 weeks, p = 0.013). There was no difference between groups in the IKDC Score (69 ± 17.2 vs. 69.9 ± 15.2, p = 0.834), Cincinnati-Sportsmedicine and Orthopaedic Centre Score (68 ± 18.3 vs. 69.4 ± 18.2, p = 0.698) and Tegner Score (3.8 ± 1.5 vs. 4 ± 1.5, p = 0.246). CONCLUSION: Allograft filling leads to faster bone union and return to full weight bearing but showed no significant advantage in terms of RTW/RTS, overall patient satisfaction and functional scores. The decision for or against filling the osteotomy gap, therefore, remains a case-by-case decision. LEVEL OF EVIDENCE: Level III, Retrospective cohort study.

Hydrogel-Based Matrix-Associated Autologous Chondrocyte Implantation Shows Greater Substantial Clinical Benefit at 24 Months Follow-Up than Microfracture: A Propensity Score Matched-Pair Analysis.

OBJECTIVE: To compare substantial clinical benefit (SCB) of a hydrogel-based, matrix-associated autologous chondrocyte implantation (M-ACI) method versus microfracture (MFx) in the treatment of knee cartilage defects. DESIGN: Propensity score matched-pair analysis, using the MFx control group of a phase III study as comparator for M-ACI treatment in a single-arm phase III study, resulting in 144 patients in the matched-pair set. RESULTS: Groups were comparable regarding baseline Knee Injury and Osteoarthritis Outcome Score (KOOS), sex, age, body mass index, symptom duration, smoking status, and previous knee surgeries. Defect sizes in the M-ACI group were significantly larger than in the MFx group (6.4 cm2 vs. 3.7 cm2). Other differences concerned location, number, and etiology of defects that were not considered to influence the interpretation of results. At 24 months, significantly more patients in the M-ACI group achieved SCB in KOOS pain (72.2% vs. 48.6%; P = 0.0108), symptoms (84.7% vs. 61.1%, P = 0.0039), sports/recreation (84.7% vs. 56.9%, P = 0.0008), and quality of life (QoL; 72.2% vs. 44.4%, P = 0.0014). The SCBs for KOOS activities in daily living and International Knee Documentation Committee score were higher for M-ACI but not significantly different from MFx. The SCB rates consistently favored M-ACI from 3 months onward. The highest improvements from baseline at 24 months in patients with SCB were observed for KOOS sports/rec. (M-ACI: 60.8 points, MFx: 55.9 points) and QoL (M-ACI: 58.1, MFx: 57.4). CONCLUSION: Hydrogel-based M-ACI demonstrated superior SCB in KOOS pain, symptoms, sports/rec., and QoL compared with MFx in patients with knee cartilage defects through 2 years follow-up.

Artificial intelligence-based analyses of varus leg alignment and after high tibial osteotomy show high accuracy and reproducibility.

PURPOSE: The aim of this study was to investigate the performance of an artificial intelligence (AI)-based software for fully automated analysis of leg alignment pre- and postoperatively after high tibial osteotomy (HTO) on long-leg radiographs (LLRs). METHODS: Long-leg radiographs of 95 patients with varus malalignment that underwent medial open-wedge HTO were analyzed pre- and postoperatively. Three investigators and an AI software using deep learning algorithms (LAMA™, ImageBiopsy Lab, Vienna, Austria) evaluated the hip-knee-ankle angle (HKA), mechanical axis deviation (MAD), joint line convergence angle (JLCA), medial proximal tibial angle (MPTA), and mechanical lateral distal femoral angle (mLDFA). All measurements were performed twice and the performance of the AI software was compared with individual human readers using a Bayesian mixed model. In addition, the inter-observer intraclass correlation coefficient (ICC) for inter-observer reliability was evaluated by comparing measurements from manual readers. The intra-reader variability for manual measurements and the AI-based software was evaluated using the intra-observer ICC. RESULTS: Initial varus malalignment was corrected to slight valgus alignment after HTO. Measured by the AI algorithm and manually HKA (5.36° ± 3.03° and 5.47° ± 2.90° to - 0.70 ± 2.34 and - 0.54 ± 2.31), MAD (19.38 mm ± 11.39 mm and 20.17 mm ± 10.99 mm to - 2.68 ± 8.75 and - 2.10 ± 8.61) and MPTA (86.29° ± 2.42° and 86.08° ± 2.34° to 91.6 ± 3.0 and 91.81 ± 2.54) changed significantly from pre- to postoperative, while JLCA and mLDFA were not altered. The fully automated AI-based analyses showed no significant differences for all measurements compared with manual reads neither in native preoperative radiographs nor postoperatively after HTO. Mean absolute differences between the AI-based software and mean manual observer measurements were 0.5° or less for all measurements. Inter-observer ICCs for manual measurements were good to excellent for all measurements, except for JLCA, which showed moderate inter-observer ICCs. Intra-observer ICCs for manual measurements were excellent for all measurements, except for JLCA and for MPTA postoperatively. For the AI-aided analyses, repeated measurements showed entirely consistent results for all measurements with an intra-observer ICC of 1.0. CONCLUSIONS: The AI-based software can provide fully automated analyses of native long-leg radiographs in patients with varus malalignment and after HTO with great accuracy and reproducibility and could support clinical workflows. LEVEL OF EVIDENCE: Diagnostic study, Level III.

Etiology, Classification, Diagnostics, and Conservative Management of Osteochondral Lesions of the Talus. 2023 Recommendations of the Working Group "Clinical Tissue Regeneration" of the German Society of Orthopedics and Traumatology.

METHODS: Peer-reviewed literature was analyzed regarding different topics relevant to osteochondral lesions of the talus (OLTs) treatment. This process concluded with a statement for each topic reflecting the best scientific evidence available for a particular diagnostic or therapeutic concept, including the grade of recommendation. Besides the scientific evidence, all group members rated the statements to identify possible gaps between literature and current clinical practice. CONCLUSION: In patients with minimal symptoms, OLT progression to ankle osteoarthritis is unlikely. Risk factors for progression are the depth of the lesion on MRI, subchondral cyst formation, and the extent of bone marrow edema. Conservative management is the adaptation of activities to the performance of the ankle joint. A follow-up imaging after 12 months helps not to miss any progression. It is impossible to estimate the probability of success of conservative management from initial symptoms and imaging. Cast immobilization is an option in OLTs in children, with a success rate of approximately 50%, although complete healing, estimated from imaging, is rare. In adults, improvement by conservative management ranges between 45% and 59%. Rest and restrictions for sports activities seem to be more successful than immobilization. Intra-articular injections of hyaluronic acid and platelet-rich plasma can improve pain and functional scores for more than 6 months. If 3 months of conservative management does not improve symptoms, surgery can be recommended.

Bipolar Lesions of the Knee Are Associated With Inferior Clinical Outcome Following Articular Cartilage Regeneration. A Propensity Score-Matched Analysis Including 238 Patients of the German Cartilage Registry (KnorpelRegister DGOU).

PURPOSE: To determine whether bipolar lesions (BL) are associated with inferior clinical outcome following articular cartilage regeneration (CR) compared to unipolar lesions (UL). METHODS: A registry-based study, including patients undergoing isolated CR for focal knee cartilage lesions was performed. Lesions were considered UL or BL depending on the opposing cartilage. Propensity score matching was applied to eliminate potential confounders. Two groups comprising 119 patients with similar baseline characteristics were matched. The Knee Injury and Osteoarthritis Outcome Score (KOOS) at baseline, 6, 12, 24, and 36 months following CR served as primary outcome measure. KOOS improvement, reaching the minimal clinically important difference (MCID), KOOS subcomponents, and failure rates were calculated. RESULTS: Autologous chondrocyte implantation (ACI) was the most frequently performed procedure in both groups with 63.0% (BL) and 46.6% (UL). There was a significant difference regarding KOOS at 24 months between UL (76.39 ± 14.96) and BL (69.83 ± 18.83; P = .028), which did not exceed the threshold of MCID. No significant difference was detected at any other follow-up. KOOS improvement from baseline was lower in the BL group at all follow-ups and peaked at 36 months in both groups (UL [26.00 ± 16.12] vs. BL [16.63 ± 17.29]; P = .024). The failure rate in the BL group was higher at 8.2% (9/110) compared to the UL group at 3.9% (4/98) (P = .256). CONCLUSIONS: BL were associated with worse clinical outcome 2 years following CR compared to UL. However, both groups showed an ongoing clinical improvement up to 3 years postoperatively and a low failure rate. While inferior clinical improvement and a lower clinical response rate may be expected in BL patients, the observed differences do not justify excluding these patients from CR. LEVEL OF EVIDENCE: Level III, retrospective comparative prognostic trial.

Current practice of concomitant surgeries in cartilage repair of the femorotibial compartment of the knee: baseline data of 4968 consecutive patients from the German cartilage registry (KnorpelRegister DGOU).

INTRODUCTION: The treatment of underlying comorbidities is a field of rising interest in cartilage repair surgery. The aim of this study was to analyze the current practice of concomitant surgeries in cartilage repair of the knee especially in the medial or lateral femorotibial compartment. Type, frequency and distribution of additional surgeries for correction of malalignment, knee instability and meniscus deficiency should be evaluated. METHODS: Baseline data of 4968 patients of the German Cartilage Registry (KnorpelRegister DGOU) were analyzed regarding the distribution of concomitant surgeries in addition to regenerative cartilage treatment. RESULTS: Beyond 4968 patients 2445 patients with cartilage defects in the femorotibial compartment of the knee could be identified. Of these patients 1230 (50.3%) received additional surgeries for correction of malalignment, instability and meniscus deficiency. Predominant procedures were leg axis corrections (31.3%), partial meniscectomy (20.9%) and ACL reconstruction (13.4%). The distribution of the concomitant surgeries varied between cartilage defects according to the different defect genesis. Patients with traumatic defects were younger (36y) and received predominantly ACL reconstructions (29.2%) (degenerative: 6.7%), whereas patients with degenerative defects were older (43y) and underwent predominantly leg axis corrections (38.0%; traumatic: 11.0%). CONCLUSIONS: This study shows the high frequency and distinct distribution of the concomitant surgeries in addition to regenerative cartilage treatment procedures. Understanding of the underlying cause of the cartilage defect and addressing the comorbidities as a whole joint therapy are of utmost importance for a successful regenerative cartilage treatment. These data provide a baseline for further follow up evaluations and long-term outcome analysis. LEVEL OF EVIDENCE: II.

Empfehlungen der AG Klinische Geweberegeneration zur Behandlung von Knorpelschäden am Kniegelenk. / 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.

Patient response to osteotomy around the knee joint at one year post-operation-fulfilment of expectations and current health status.

INTRODUCTION: The aim of this study was to investigate patient satisfaction and fulfilment of expectations after osteotomy around the knee at one year postoperatively, using patient-related outcome measures. MATERIALS AND METHODS: From the initial sample of 264 patients, a total of 132 patients (age 48y ± 11) were enrolled in this prospective study (response rate 49.3%). Data were collected using the Hospital For Special Surgery-Knee Surgery Expectations Survey (HFSS-KSES), items for satisfaction and the Knee injury and Osteoarthritis Outcome Score (KOOS) measures. At one year postoperative follow-up, an individualized questionnaire asked whether the specific person-related expectations had been fulfilled. RESULTS: Satisfaction was high with 83.2% of all participants at one year after surgery. A total of 78% of patients stated they would decide to do the surgery again. This decision was significantly associated with satisfaction, younger age and better KOOS scores scales before surgery for pain, activity and sports. We found high correlations between satisfaction and fulfilment of expectations for the HFES-KSES. Fulfilment of expectations one year after surgery was significantly associated with significant improvements in KOOS scales at one year post-operation. Expectations (1) "to get the knee back to normal status", (2) "improve ability to squat", (3) "improve ability to run", (4) "improve ability to kneel" had been fulfilled worst. A multiple linear regression model for satisfaction had an R2 = 0.797 of the variance. The most influential was the variable fulfilment of "maintain health" that had 70.7% of variance. CONCLUSIONS: The fulfilled expectation concerning an improvement of the ability to maintain health was the most influential parameter for satisfaction at one year post-osteotomy. Patients with better health status of the knee and younger age rated the surgery to be more positive and were also more likely to do the surgery again. This provides an indication for an earlier intervention, before the knee and overall health status becomes more detrimental. LEVEL OF EVIDENCE: Level II (Therapeutic study).

Biological Reconstruction of Localized Full-Thickness Cartilage Defects of the Knee: A Systematic Review of Level 1 Studies with a Minimum Follow-Up of 5 Years.

OBJECTIVE: The objective of this study was to evaluate the best available mid- to long-term evidence of surgical procedures for the treatment of localized full-thickness cartilage defects of the knee. DESIGN: Systematic review using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines of Level 1 randomized clinical trials (RCTs), meta-analyses of RCTs and systematic reviews with a minimum follow-up of 5 years. Data extracted included patient demographics, defect characteristics, clinical and radiological outcomes, as well as treatment failures. RESULTS: Six RCTs and 3 Level 1 systematic reviews were included. Two RCTs compared microfracture (MFx) to periosteum-covered autologous chondrocyte implantation (ACI-P), 1 to matrix-associated ACI (M-ACI) and 2 to osteochondral autograft transplantation (OAT). One study compared OAT to collagen membrane covered ACI (ACI-C). The 3 Level 1 systematic reviews/meta-analyses assessed the outcome of MFx, OAT, and various ACI methods in RCTs. OAT showed significantly better outcomes compared with MFx. In the 2 RCTs comparing ACI-P and MFx, no significant differences in clinical outcomes were seen, whereas significantly better outcomes were reported for M-ACI versus MFx in 1 study including patients with larger defects (5 cm2), and for ACI-C versus OAT in terms of Cincinnati Score. Higher failure rates were reported for MFx compared with OAT and for OAT compared with ACI-C, while no significant differences in failure rates were observed for ACI-P compared to MFx. CONCLUSION: Restorative cartilage procedures (ACI-C or M-ACI and OAT) are associated with better long-term clinical outcomes including lower complication and failure rates when compared with reparative techniques (MFx). Among the restorative procedures, OAT seems to be inferior to ACI especially in larger defects after longer follow-up periods. LEVEL OF EVIDENCE: Level I: Systematic review of Level I studies.

Effect of Previous Knee Surgery on Clinical Outcome After ACI for Knee Cartilage Defects: A Propensity Score-Matched Study Based on the German Cartilage Registry (KnorpelRegister DGOU).

BACKGROUND: Autologous chondrocyte implantation (ACI) is an established procedure for the treatment of cartilage damage in the knee joint. At present, it is still unclear how previous surgery influences outcome after ACI. PURPOSE: To evaluate the effect of previous knee surgery related or nonrelated to the treated cartilage defect on clinical outcome after ACI for knee cartilage defects. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: An overall 730 patients with ACI who underwent previous unspecific knee surgery, whether related to the defect being currently treated or not, were identified from a cohort of 5961 patients registered in the German Cartilage Registry. Propensity score matching was used to match these patients to 690 patients with analogous characteristics but without previous surgery. Subsequently, 317 patients with previously failed cartilage treatment at the defect site were identified and compared with a matched collective of 254 patients without previous cartilage treatment. In a subgroup analysis, the type of previous cartilage surgery was additionally investigated. Outcome was evaluated by Knee injury and Osteoarthritis Outcome Score (KOOS), visual analog scale for pain, rate of reintervention, and patient satisfaction up to 36 months. A chi-square test was used to compare categorial variables and an unpaired t test to compare continuous variables. RESULTS: Patients with previous knee surgery not related to the cartilage defect showed a lower KOOS at 6 months (68.3 vs 70.8; P = .026), while patients with previous cartilage surgery showed significantly lower KOOS values at all follow-up time points when compared with patients without any previous knee or cartilage surgery (all P < .05). A comparison of KOOS values in patients with previous therapy at the cartilage defect with ACI versus bone marrow stimulation did not show any significant differences at any follow-up. CONCLUSION: Previously failed cartilage treatment at the defect site represents a negative prognostic factor up to 3 years after ACI. However, this influence appears to be independent of the type of previous treatment at the defect site and applies equally to failed bone marrow stimulation as well as previous ACI. In contrast, a negative effect of previous surgery to the knee unrelated to the cartilage defect could not be shown in the 3-year follow-up.

Factors correlating with patients' satisfaction after undergoing cartilage repair surgery-data from the German Cartilage Registry (KnorpelRegister DGOU).

Subjective patient satisfaction is the most relevant parameter for assessing the success of treatment after orthopaedic surgery. The aim of the present study was to correlate patient-reported outcome parameters (i.e., absolute KOOS, KOOS increase) and revision-free survival with patient's satisfaction. Furthermore, the study aimed on the identification of pre-operative factors that are associated with patient's satisfaction after the surgery.For the present study, 6305 consecutive patients from the German Cartilage Registry (KnorpelRegister DGOU) were analyzed. Patient characteristics and outcome were correlated with patients' satisfaction after a follow-up of three years by Spearman correlation. P values < 0.05 were considered statistically significant.Mean age was 37 ± 12.5 years, 59.7% patients were male, and 40.3% female. Most patients (46.7%) were treated with an autologous chondrocyte implantation (ACI). The strongest correlation of subjective satisfaction and the subscore quality of life (r = 0.682; p < 0.001) was found, whereas the post-operative increase in KOOS from the pre-operative value showed only a moderate correlation (r = 0.520; p < 0.001). There was also a significant correlation with the absolute KOOS value (r = 0.678; p < 0.001), the subscores pain (r = 0.652; p < 0.001), quality of life (r = 0.682; p < 0.001), and sports (r = 0.633; p < 0.001), whereas symptoms (r = 0.504, p < 0.001) and activities of daily life (r = 0.601; p < 0.001) showed a weaker correlation. Pain also correlated highly significant with the patient satisfaction 24 months after surgery (r = - 0.651, p < 0.001). The correlation between satisfaction after the 2nd and 3rd year (r = 0.727; p < 0.001) is stronger than correlation after six months and three years (r = 0.422, p < 0.001). All pre-operative parameters show a very weak correlation (r < 0.1).The use of standardized measuring instruments (KOOS and Pain) is a relevant outcome parameter in science and clinical practice, whereas absolute values represent satisfaction better than the individual increase. The subscores "pain," "quality of life," and "sports" represent satisfaction better than the subscores "symptoms" and "activity of daily life." Early satisfaction has only a moderate predictive value for satisfaction after 3 years, which is of great practical relevance in particular for the assessment of potential treatment failures. It is remarkable to note that a revision surgery is only very mildly associated with increased dissatisfaction. Pre-operative factors are not reliable prediction factors for post-operative patient satisfaction.

Autologous chondrocyte implantation combined with anterior cruciate ligament reconstruction: similar short-term results in comparison with isolated cartilage repair in ligament intact joints.

PURPOSE: Both acute ruptures of the anterior cruciate ligament (ACL) as well as chronic ACL insufficiency show a high association with focal cartilage defects of the knee. However, the results after combined ACL reconstruction and cartilage repair are not well investigated. The aim of the present study was to investigate the short-term outcomes after autologous chondrocyte implantation (ACI) in combination with ACL reconstruction and to compare the results with patients who underwent isolated ACI in ligament intact knees. METHODS: All patients who were registered in the German Cartilage Registry with ACI for focal cartilage defects in the knee joint in combination with ACL reconstruction and who completed the 24 month follow-up were included in the study group. A matched-pair procedure according to gender, defect location, defect size, and age was used to create a control group of patients with isolated ACI in ACL intact joints. The Knee Injury and Osteoarthritis Outcome Score (KOOS) and the numeric analog scale for pain (NAS) were used to assess the preoperative state as well as the clinical outcomes 12 and 24 months after surgery. RESULTS: A total of 34 patients were included in both the study group (age mean 33.3 ± SD 8.8 years) and the control group (33.6 ± 8.4 years) with a median defect size of 466 (25%-75% IQR 375-600) mm2 and 425 (IQR 375-600) mm2, respectively. In comparison with the preoperative state (median 67, IQR 52-75), the study group showed a significant increase of the total KOOS after 12 months (78, IQR 70-86; p = 0.014) and after 24 months (81, IQR 70-84; p = 0.001). The NAS for pain did not change significantly in the postoperative course. In comparison with the control group there was no significant difference for the total KOOS neither preoperative (control group median 67, IQR 52-73) nor at any postoperative time point (12 months: 82, IQR 67-93; 24 months: 81, IQR 71-91). CONCLUSION: The clinical short-term outcomes after ACI at the knee joint in combination with ACL reconstruction are good and similar to the results after isolated ACI in ligament intact knees. LEVEL OF EVIDENCE: III.

Cell-based treatment options facilitate regeneration of cartilage, ligaments and meniscus in demanding conditions of the knee by a whole joint approach.

PURPOSE: This article provides an update on the current therapeutic options for cell-based regenerative treatment of the knee with a critical review of the present literature including a future perspective on the use of regenerative cell-based approaches. Special emphasis has been given on the requirement of a whole joint approach with treatment of comorbidities with aim of knee cartilage restoration, particularly in demanding conditions like early osteoarthritis. METHODS: This narrative review evaluates recent clinical data and published research articles on cell-based regenerative treatment options for cartilage and other structures around the knee RESULTS: Cell-based regenerative therapies for cartilage repair have become standard practice for the treatment of focal, traumatic chondral defects of the knee. Specifically, matrix-assisted autologous chondrocyte transplantation (MACT) shows satisfactory long-term results regarding radiological, histological and clinical outcome for treatment of large cartilage defects. Data show that regenerative treatment of the knee requires a whole joint approach by addressing all comorbidities including axis deviation, instability or meniscus pathologies. Further development of novel biomaterials and the discovery of alternative cell sources may facilitate the process of cell-based regenerative therapies for all knee structures becoming the gold standard in the future. CONCLUSION: Overall, cell-based regenerative cartilage therapy of the knee has shown tremendous development over the last years and has become the standard of care for large and isolated chondral defects. It has shown success in the treatment of traumatic, osteochondral defects but also for degenerative cartilage lesions in the demanding condition of early OA. Future developments and alternative cell sources may help to facilitate cell-based regenerative treatment for all different structures around the knee by a whole joint approach. LEVEL OF EVIDENCE: IV.