Abstract
Autologous micro-fragmented adipose tissue (MFAT) for the treatment of symptomatic knee osteoarthritis (OA) is gaining interest although there is still a lack of supportive data on safety and clinical efficacy. This study primarily aimed to identify patient- and pathology-related parameters to tighten patient selection criteria for future clinical MFAT application. Secondly, the overall (1) therapeutic response rate (TRR), (2) short-term clinical effect, (3) effect durability and (4) therapeutic safety was investigated at a minimal follow-up of 1 year.
Sixty-four subjects (91 knees) with symptomatic knee OA (mild-severe on MRI) were enrolled in a prospective single-centre case series. Ethical approval was obtained from the local and academic ethical committee (#B300201733775). After liposuction, the adipose tissue was mechanically processed in a Lipogem® device which eventually produced 6–9cc 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 meticulously recorded. The TRR was defined according to the OMERACT-OARSI criteria. A baseline MRI was scored following the MOAKS system. Paired sample t-tests, independent t-test and Fischer's exact test were applied on appropriate variables. Multiple regression models were fit separately for patient-and pathology-specific factors. Significance level was set at α=0.05.
The overall TRR was 66% at 3 months and 50% at 12 months after injection. Subgroup analysis revealed that specifically patients with no-mild bone marrow lesions (BML) had a TRR of 88% at 3 months and 75% at 12 months after MFAT injection. Therapy responders at these timepoints improved with 29.3±14.1 points and 30.8±15.3 points on KOOS pain, while non-responders deteriorated mildly. All clinical scores were significantly higher at follow-up compared to baseline (p<0.05). BMI (factor 0.17, p=0.002) and age (factor −0.48, p=0.048) were prognosticators for the TRR% at 1 month and for absolute KOOS pain improvement at 6 months, respectively. Posterior horn lesions (PHL) in the medial meniscus (p<0.001) and bone marrow lesions (p=0.003) were negative prognosticators for the TRR at respectively 6 and 12 months post-injection. An inflammatory reaction (pain, swelling or stiffness) to MFAT was reported in 79% knees and resolved spontaneously within 16.6±13.5 days after administration.
The study showed a durable and satisfying TRR (up to 75% at 1 year in selected patients without BML) and clinical improvement after a single intra-articular injection with autologous MFAT. The availability of an index knee MRI is mandatory to select MFAT patients, preferably with no or mild BML and without PHL of the medial meniscus. High BMI and younger age are associated with better early outcomes. In comparison to other injection therapies such as cortisone, hyaluronic acid and PRP, MFAT appears very attractive with an effect durability of at least 1 year.
