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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]