Purpose:
To evaluate mid-term outcomes of injectable matrix-associated autologous chondrocyte transplantation (MACT) for acetabular cartilage defects in femoroacetabular impingement (FAI), comparing two different ACT products (NOVOCART® Inject vs. Chondrosphere®) using data from the German Cartilage Registry.

Methods:
This retrospective analysis included 91 FAI patients (mean age 31.5 years) with isolated International Cartilage Repair Society (ICRS) Grade 3 or 4 acetabular cartilage defects treated arthroscopically with either NOVOCART® Inject (n = 48) or Chondrosphere® (n = 43), with a mean follow-up of 41.8 ± 18.5 months. Clinical outcomes were assessed using the International Hip Outcome Tool (iHOT33) and Visual Analogue Scale (VAS) for pain at 6, 12, 24, 36 and 60 months. Clinically important outcome values (minimum clinically important difference, Patient Acceptable Symptom State, substantial clinical benefit) were calculated at 36 months. Subgroup analysis compared defect severity (ICRS Grade 3 vs. 4) and product-specific outcomes.

Results:
Significant improvement in hip function (iHOT33) was observed across all follow-up time points in both groups (p < 0.01), with no significant between-group differences in iHOT33 scores or longitudinal trajectories. Within-group VAS pain scores improved significantly over time in the Chondrosphere® group (p < 0.01), whereas the improvement in the NOVOCART® Inject group did not reach statistical significance; however, no significant difference in pain outcomes was found between the two products. At 12 months, patients with ICRS grade 3 defects had significantly higher iHOT33 scores (73.1 vs. 60.5) and lower VAS pain scores (2.1 vs. 2.8) than those with grade 4 lesions.

Conclusion:
Arthroscopic MACT was associated with clinical improvement in pain and function up to 5 years in FAI patients with acetabular cartilage defects, with no statistically significant differences detected between hydrogel-based and spheroid-based products; follow-up data at later time points were more limited for NOVOCART® Inject. Although statistically significant pain improvement over time was observed only in the Chondrosphere® group, no significant differences in pain outcomes between the two products were detected.