Autologous Micro-Fragmented Adipose Tissue (MFAT) to Treat Symptomatic Knee Osteoarthritis: Early Outcomes of a Consecutive Case Series

Abstract

The study aimed to evaluate the short-term clinical effect, therapeutic response rate (TRR%), and therapy safety of a single intra-articular autologous MFAT injection for symptomatic knee OA. Secondly, patient- and pathology-related parameters were investigated to tighten patient selection for MFAT therapy. Sixty-four subjects with symptomatic mild-severe knee OA were enrolled in a single-center trial and received a unilateral (n = 37) or bilateral (n = 27) MFAT injection. After liposuction, the adipose tissue was mechanically processed with the Lipogem^® device, which eventually produced 8-10 cc of MFAT. Subjects were clinically assessed by means of the KOOS, NRS, UCLA, and EQ-5D at baseline and 1, 3, 6, and 12 months after injection. Adverse events were recorded at each follow-up timepoint. The TRR was defined according to the OMERACT-OARSI criteria and baseline MRI was scored following the MOAKS classification. The TRR of the index knee was 64% at 3 months and 45% at 12 months after injection. Therapy responders at 12 months improved with 28.3 ± 11.4 on KOOS pain, while non-responders lost -2.1 ± 11.2 points. All clinical scores, except the UCLA, improved significantly at follow-up compared to baseline (p < 0.05). In the bilateral cohort, no difference in baseline scores or TRR was found between the index knee and contralateral knee (n.s.). An inflammatory reaction was reported in 79% of knees and resolved spontaneously within 16.6 ± 13.5 days after MFAT administration. Numerous bone marrow lesions (BML) were negatively correlated with the TRR at 12 months (p = 0.003). The study demonstrated an early clinical improvement but a mediocre response rate of 45% at 12 months after a single intra-articular injection with autologous MFAT. Assessment of bone marrow lesions on MRI can be helpful to increase the therapeutic responsiveness of MFAT up to 70% at 12 months. In comparison to repetitive injection therapies such as cortisone, hyaluronic acid, and PRP, administration of MFAT might become a relevant alternative in well-selected patients with symptomatic knee OA.

Keywords: adipose tissue; autologous; biological; knee; osteoarthritis.

Figure 1

The OMERACT-OARSI criteria to define responding and non-responding subjects to treatment interventions in knee osteoarthritis. The therapeutic response rate (TRR%) is derived from this classification at respective follow-up timepoints after MFAT administration.

Figure 2

Flowchart of patient enrollment according to the standards of reporting trials statement with numbers of excluded and analyzed subjects. (MFAT, micro-fragmented adipose tissue; FU, follow-up).

Figure 3

KOOS outcomes of the index knees (n = 64) after a single injection with autologous MFAT. (ADL, activities of daily living; QoL, quality of living). * significant difference compared to baseline. ** significant difference compared to baseline and 1 month.

Figure 4

Overall therapeutic response rate (TRR) and associated absolute change in (a) KOOS pain and (b) KOOS activities of daily living (ADL) relative to baseline.

Figure 5

MOAKS outcome on baseline index knee MRI (n = 47). (MCCW, medial compartment cartilage wear; LCCW, lateral compartment cartilage wear; PFCW, patella-femoral cartilage wear; BML, bone marrow lesions).

Figure 6

Therapeutic response rate (TRR%) for bone marrow lesion (BML) classification.